ML20042E836
| ML20042E836 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 12/31/1989 |
| From: | NORTHEAST UTILITIES |
| To: | |
| Shared Package | |
| ML20042E834 | List: |
| References | |
| NUDOCS 9005030202 | |
| Download: ML20042E836 (266) | |
Text
{{#Wiki_filter:- l # 12 ? ! I t \ a @ y + = 5 ; + 6 # M M w ; 7 d. : a u.. !-
..<. ;.,q v
; 4 4 j gidy.;Q-
..., t- -
~
4 .- - f.j . 2 4% - . .M , ~ . , _y
' yM f
+ 3 4. 3. , 4 ,f M s,.
M y 7 p:,.
.; ftApipAf' W : 4C " j 4. < g 4 * .,, .. f'. . .
e, *' y y g:g,& kh q'qr w f: ~ x .; c..~. ,
.,. Jw.. .a p ,,
u#- t
* . . g f ,,;-
. - l L- ,.
..> . . -a. :- ,
1 Monitoring the Marine Environment of Long Island Sound i at Millstone Nuclear Power Station Waterford, Connecticut l 1 l ANNUAL REPORT 1989 NORTHO:AST UTH.ITIES NU ENVIRONMENTAL LAB 1 E j '~ E APRIL 1990 t cL := ;. _ ,.:,, = .,, L
)
l we:w7mmmmmmyggp% e w.w' . . a t. . .
+.a.y : an 3 3 , i
+
, 2.t f ' -
. w. ~, @ gggMM l * ,) ,Y. "
4% x ,. ' gu g e, . 3 . s .p <-]y1 fMf.[*.'b c - s . e .- , ; .: . . , .3 .. m l **
, ,~ . f. , . . ' {. . L ,. l . ' " . ~ g. +
1 ) p.& g' .w).NjQV
' 'Y '
i4%
- Q . * ' ,.jl !MVkb A
. . .. gf,3l i '7 - '
k's -: '
, . ' , .[
t' t ( l .
., . .4 +
.k ' i l l. f ' + l .. ,;
/g % . n:. : vM23 1 .z; r T . ,. _' '.;~. ~ . ;. 4
- f. n. <
./ :s 93; l
' ', s
..,. .e?. . ;~ ~. .
.,Q.? ,
.v '
A. .<.;-w L G97,)'
. -3
. . . ':.; n ,,,. . .. . '
J,..., , ;. a e ' *y ; .> w , ; , . . J:.
' V3
.* .m*'* -
~~,, -. .,
,,cpuwr g<sm , p + : . s. s 2 .
.. 7 .,
n Q u- f+ % h;;V R . & Mp~f.Mwg . .. ; - .n gg] F 34
- FWA 7 e:;p. .x . \
I y . .g .
. . mJ ;:
yke - A r >,. .. ., n . 1
. g
, - y .-
1
~
n w.nv. -
, 3, .,.
1 g .. ..
.w
.~ ~,.s -
~. - -
.pWW.
- .pn ;}y s , y; + wyt 4 w '. s.y.
..< , , : . . v y y g;.n ., ,
=
..E y ..
u.- -
. . .g '
[1 , l, ; : ,- -,- - ' -. f.' L. , .__ , a - _ ,. p g z ; y (..; ' - < :: . ? A ;'
,' ' ,v s
,i; ,. ,: - .,
ggs .....>...,q ]
- - ., c l
1 l l l 1 l 1 Monitoring the Marine Environment l
) of Long Island Sound l at Millstone Nuclear Power Station i Waterford, Connecticut i I. .
ANNUAL REPORT 1989 : I l ! PMMtTHI!A!iT tlTH.ITHifi ' NU ENVIRONMENTAL LAB l 1 APRIL 1990 L ; l t . L _.
( , ,. Monitoring the Marine Environment of Long Island Sound at Millstone Nuclear Power Station , 1989 Anuual Report ; Northeast Utilities Environmental Laboratory i i 4 April 17,1990 i i i Waterford, Connecticut i
.yaus,v-r~ + n n ,v~~ ~ ~ ~ ~ ~ ~ ~ ~mem-- ~ ~ + ,v m ~ w n -~ w n ~ ~ - w ~-m--m q,m~~~m,
. p
.,3
}
. s b
- , :)
-e <
t t P 1 9 i
-t i
t t t, t [
-t 5
E y h I i k
'i 1 t.
.r
.g r
.ts P
'P 1
s [. Y. te k L e r r s S h 1-E Y 11 Monitoring Studies,1989 s l e ?, k'
~ . mm-
F~ Preface This report was prepared by the Northeast Utilities Service Company Erwironmental Laboratory (NUEL) staff. All contributors are acknowledged according to their respective disciplines. Ilenthic Eco!agy: Fish Ecology: _ Statistleal Support: Dr. Milan Keser, Supervisor Dr. Linda E. Bircley, Supervisor Dr. Ernest Lorda James F. Focrtch John A. Castleman Raymond O. lleller David P. Colby NUEL Malling Address: Donald F. Landers Donald J. Danila NU Environmental l_ab I Richard A. Larsen Gregory C. Decker PO Box 128 Douglas E. Morgan David O. Dodge Waterford, Connecticut 06385 John T. Swenarton Christine P. Gauthier Joseph M. Vozarik JoAnne Konefal J. Dale Miller Special thanks are extended to Dr. William C. Renfro, Director, Environmental Programs Department, Paul M. Jacobson, Manager, Environmental Services (NUSCO) and the following members of the Millstone Ecological Advisory Committe for their critical review of this report: Dr. John Tietjen, Dr. Nelson Marshall, Dr. Saul Salla, Dr. William Pearcy, Dr. Robert Wilce and Dr. Robert Whitlatch. , Coven Aerial photograph of the Millstone Power Nuclear Station, Waterford, Connecticut. l 1 l l :1 L i Preface lii l i i 1
T A i' q
'I t
i iv Monitoring Studies,1989
Executive Summary Winter Flounder Studies The effect of MNPS operation on the winter flounder (Pseudop/curonectes americames) has been under study since 1973. A winter flounder stock spawns locally in the Niantic River, so impacts due to MNPS, particularly entrainment of larvae through the cooling water system, are of concern because of the value of the species to the sport and commercial fisheries of Connecticut. Abundance and various aspects of the reproductive biology of adult winter flounder spawning in the river have been investigated since 1976. The median trawl catch per unit effort (CPUE) of winter flounder larger than 15 cm in the Niantic River during the 1989 spawning season was 12.2, the second smallest index of the 14-year series. Because of poor year classes produced in the mid-1980's, the spawning population since . - 1985 has primarily been comprised of increasingly older and larger fish each successive year. Estimates of absolute abundance hau been based on mark and recapture methods and the Jolly stochastic model. The adult winter flounder spawning population ranged between 48 and 77 thousand fish during 1984-88. Sampling intensities were relatively low (0.03f0.08), indicating potentially inaccurate abundance-estimates. However, a good correspondence was found between annual median trawl CPUE and the Jolly estimates. Based on thic relationship, total numbers of winter flounder spawning in the Niantic River may have been as large as 20u,000 fish during their peak abundance in 1981. The annual standardized catches for 1984 87 were found to represent about 2.8 to 4.5% of each corresponding annual population estimate, with a geometric mean of 3.24% Assuming a similar proportion for all survey years, a multiplier of 30.864 (100/3.24) was used to scale relative numbers of females and eggs into absolute numbers for assessment purposes. Use of this scaling factor with annual sex, age, and size composition data enabled the estimation of female winter flounder parental stock size for use in the Ricker form of the stock-recruitment relationship (SRR). The sex ratio of Niantic River winter flounder each year tended to favor females (long term geometric mean of 1.34 females per male). Spawning takes place from January through late March or early April each year. As spawning activity was apparently positively correlated with water temperature, egg deposition was completed earlier in recent years, which had warmer winters. l l Mature female fish made up between a third and a half of the annual catches of winter flounder taken l in the Niantic River during the spawning period. Estimated population abundance ranged from about 20 I to 85 thousand during 1977 88; the largest numbers of spawners were present during the early 1980s. Total ( egg production (12 49 billion) also peaked then, but mean fecundity has increased in recent years as older and larger females made up a larger proportion of the spawners than in previous years. Annual abundance estimates of larval winter flounder have been available at the MNPS discharge (entrainment sampling) since 1976, from a station in Niantic Bay since 1979, and at three stations in the Niantic River since 1983. The pattern of abundance for larval winter flounder in 1989 at these stations was similar to previous years of sampling. Abundance of larvae in the river during 1989 was the second highest observed during the past 7 years, following that for 1988, in the river, abundance peaked in early March and then rapidly declined, but in the bay an increase occurred from mid March to mid; April. The sequence of these changes suggested that many larvae are flushed from the river to the bay each year. The annual abundance of yolk sac larvae (Stage 1) ir, the river was positively correlated to the reproductive capacity of the spawning stock and indicated that egg hatching rates were consistent from year to year. The temporal occurrence of each developmental stage in the river and bay showed that a majority Executive Summary vii
)
i j ; of the spawning occurred in the river and that flushing of larvae from the river to the bay took place primarily during Stage 2 of development. ~ The time of peak abundance for Stages 3 and 4 larvac was ^ generally similar between the river and bay over the last 7 years.
' Estimated annual larval growth rates were based on weekly mean lengths of larvac collected at the lower river and in the bay. Examination of water temperatures in these areas showed that growth in the bay was positively cortclated with water _ temperature. However, this relationship was not apparent in the lower river.
The lowest growth rates in the river coincided with the greatest densities, suggesting density-dependent growth that may have been related to levels of available prey. The annual dates of peak abundance.in the - bay were also correlated to mean water temperature in March and _ April, suggesting that growth and they rate of larval development were related.- ,
~
The greatest larval mortality was found during Stage 2 of development, which is when first feeding occursc -l Tnis may be considered a ' critical period" for winter flounder. Total larval mortality from 1984 throughi l 1989 ranged from 84.6 to 97.9%, with a mean instantaneous rate of 2.92. Evidence of density-dependent mortality during larval development was indicated by increased annual mortality corresponding to increased annual egg production. Post larval age.0 winter flounder have been sampled,in Niantic River since 1983 and'Niantic Bay since = 1988. Larger numbers of larvae initially metamorphosed in the bay, but because densitics there decreased - ; greatly throughout the summer, relatively few fish remained at the bay stations towards the end of the-season. Abundance in the river peaked in late June and declined to levels of 5 to 10 fish per 100 m? by the end of the season. Based on apparent differences in the rate of growth between areas, seemingly few. y or no young moved from the bay into the river over the course of summeri Throughout_ the years of study, .
~
growth appeared to have been inversely related to density, but mortality was apparently not innuenced by - abundance. y On the basis of young-of the year fish abundance, the year-class in 1989 was smaller than the one forn 1988, which was the strongest one observed since the beginning of the sampling in 1983. Although absolute ; , mortality is. greatest during larval stages, winter flounder year-class strength is ~neverthcless probably - 1 influenced considerably by events during the first summer of life following larval metamorphosis.~ Predation on newly metamorphosed winter flounder by the sand shrimp (Crangon septemspinosa) was suggested as one important source of juvenile mortality, i At the end of the summer, young disperse into deeper waters of Niantic River and Bay.- The 6 mean, an index of abundance was 29.6 for age-O winter flounder in late fall and early_ winter in 1988-89 and was the largest in 13 years, which was another indication of the strong year class produced in 1988. The 6- ; mean index generally correlated with beam trawl CPUE of the same fish in the Niantic River during the previous summer, but not with the median otter trawl CPUE of juvenile fish taken incidentally during the~ subsequent February-April adult spawning survey. For example, the CPUE of juveniles taken during the, 1989 adult survey was 7.9, which was smaller than the value of 11.2 for 1988E Factors such as sampling variability and differential distribution of juveniles within and outside of the river most likely affected the; J reliability of the otter trawl median CPUE as an'in' icator d of relative abundance for a particular year-class. Based on limited comparisons, no correlation has yet been found between the indices of abundance for age-O fish and those for adults in subsequent years. Most correlations among abundance indices of various winter flounder life-history stages were not significant and variability due to compensatory processes did not appear to be a likely explanation for this lack of correlation.
- To determine the SRR, annual standardized catches of winter flounder taken during the spawning surveys ; l were partitioned into various age-classes by using an age length key specific for Niantic River winter flounder. Assuming an instantaneous mortality rate of 0.85,it was apparent that large fractions of age-3 -
viii Monitoring Studies,1989 ' 4 I i
(82%) and age 4 (60%) females did not enter the Niantic River, most likely because they were still ; immature. Thus, Niantic River winter flounder were not fully recruited until ages 5 or 6. Because correlation analysis showed little correspondence among early life-stages and abundance of older age-classes, p estimates of year-class recruitment needed for the SRR were determined from numbers of aged spawners , scaled up to population size by the same factor used for parental stock estimates. y The estimated recruitment for the 1985 year class was less than expected, given the parental stock size and February water temperature for that year. The three parameter (a, ,and ) Ricker SRR with a negative February temperature effect provided a conservative estimate for a (compensatory rm;rve parameter) of 2.646. This value was within the range of estimates for a of 2.22 to 2.59 calculaxa for several other Southern New England winter flounder stocks. Two biological reference points determined with the Ricker SRR for Niantic River winter flounder included the theoretical equilibrium size of the stock (P,,p; 43,659) and the fishing rate for recruitment overfishing (Fao; 0.868). Basic life-table parameters, initial spawning stock size, the three-parameter estimates of_ the SRR, ! February water temperature statistics, and specific model run simulation parameters were used to initialize the winter flounder population model. Both deterministic and stochastic model runs were made. In the latter case, 50 time-series replicates were generated with annual February temperature and a " noise" - component as random variates. The model was calibrated with the stock recruitment data. Simulation , studies that repeatedly fit the SRR to random time-series of model generated data produced estimates of i pand as precise as or better than actual data and for a correctly in about 70% of the runs. , The deterministic stock assessment investigated the response of the spawning stock to increasing exploitation by projecting the initial stock size under different fishing rates. Predicted sustainable stock sizes . were 39,539 female spawners at F=0.55, 33,491 at F=0.60, and 27,575 at F=0.65. The latter stock size represented a 40% reduction relative to the 1977 85 mean stock size of approximately 45,000 female : spawners. t A baseline or reference stock was created, consisting of 50 replicates of a stochastic stock series under conditions prior to 1986 (two unit MNPS operation). The mean stock size generated was 39,643, a value very close to the deterministic equilibrium stock size of 39,595 for the same F (0.55).' The variability (CVv38%) of the series appeared to be realistic, but the maximum stock size of about 49,000 fish was well below the record stock sizes of over 80,000 fish that occurred in the early 1980's. The tendency of the simulated population to produce smaller dominant year classes suggested that fishing rates in the past were
- less than 0.55. Examples of simulated und actual age composition of the stock appeared to be in fairly good l agreement.
Actual MNPS impact is measured each year by the number of larvae entrained through the cooling-water system. The median larval density of 165.7 per 500 m3 in entrainment collections in 1989 was about i twice as large as the value of 86.1 for 1988. However, the estimated total number of larvac entrained (131.3 million) was similar to the totals for 1986 88 (109.4-138.0 million) because of the smaller volume of water i used by MNPS operation this year, About three fifths of the entrained larvae were in Stage 3 of <! development, which was similar to the long term average. The annual entrainment estimates were compared with indices of abundance for older life-stages. No significant correlations were found that would have indicated an adverse effect related to larval entrainment on year class strength of winter flounder. i l Results of probabilistic risk assessments concerning the long term effect of year-class reductions due to both higher fishing rates and larval entrainment under three-unit MNPS operation provided the most l conservative estimates of stock reduction probabilities. The most likely stock reductions predicted were in l the order of 5% to 10%, depending on the larval entrainment rates simulated, and only in one instance
- among all the simulations conducted was the stock reduction greater than 50%. However, these reductions will apply to increasingly smaller spawning stocks unless the apparent trend of recent higher fishing rates l
Executive Summary ix j 1 l
1 is reversed.' Present rates of about 0.65 are already.high enough to weaken the effect of dominant year. classes that sustained the stock when exploitation rates were moderate. Finally, the probability of stock collapse was essentially zero for the conditions and impacts simulated. Fish Ecology Studies [ Fish assemblages in the Millstone area could be affected by the operation of MNPS in several ways. The mortality rates of early life history stages may be increased by entraining eggs and larvac through the ' condenser cooling water system. Juvenile and adult fishes could be lost due to impingement on the intake screens. ' The local distributions could be altered by the thermal plume. Since 1976, over one hundred fish taxa have been collected in demersal trawl, shore zone seine, and-ichthyoplankton sampling programs. Six taxa were selected for detailed examination due to their prevalence 7 in entrainment collections or their abundance in the shore-zone area of Jordan Cove, an area which may - experience periodic temperature increases from the thctmal plume. Long term trends in abundance werc ! examined for various life stages of potentially impacted taxa.- The American sand lance was primarily collected as larvae and was a dominant entrained taxon. Annual sand lance larval abundance was linked to water temperature, and even though annual larval abundance lluctuated substantially, March water temperatures explained some of the variation. t Most life history stages of anchovies were collected in the MNPS sampling programs. Juveniles were caught by trawl, and eggs and larvac were found in entrainment samples. In 1988, larval densitics were low and egg densitics were nt an historical low. Comparisons of annual egg and larval abundance indices suggested compensatory mortality during the early life history stages, which could help mitigate losses due to entrainment. Silversides dominated the shore-zone area of Jordan Cove and adults were abundant in winter trawl collections. There were no apparent changes in annual or seasonal abundance or distribution of seined silversides in Jordan Cove aclated to the three unit thermal plume. Larval, juvenile and adult grubby were collected in ichthyoplankton and trawl samples. Although larval-grubby entralnment increased with the operation of Millstone Unit 3, no adverse measurable abundance decrease of any life history stages occurred. The tautog is an important commercial and recreational fish in the Millstone area, and the greatest potential impact of MNPS is through egg entrainment. Egg abundance, an index of adult stock size, had an upward abundance trend in recent years, but larval densities have declined. An apparent poor egg to larval survival occurred in all years examined, with the lowest rates occurring after 1983. Abundances of most life history stages of cunner collected near MNPS have declined,' but juvenile abun-dance in 1988 increased, especially at Jordan Cove. Part of the decreasing trend in ' adult abundance was probably a result of removal of preferred habitat at intake. A low egg-to-larval survival for all years was ". apparent, and poorest survival occurred in recent years, similar to tautog. 1 Higher proportions of juvenile tautog and cunner were collected in trawls during the three unit opera-l tional period than during the two-unit operational period. This change in size distribution could not be attributed to increased entrainment due to higher cooling water usage for three-unit operation, because increasing entrainment losses should result in decreasing juvenile abundance and increasing proportions of older age fish. x Monitoring Studies,1989
4 IAbster Population Dynamics
- De American lobster (//omarus americanus) is the*most valuable commercial species in Long Island 1
- Sound. Because lobsters are highly exploited throughout their range, new regulations were implemented by all New England states to increase the minimum legal size. In Connecticut, the minimum legal size was 3 7 increased from 81.0 mm (3 /16 in) in 1988 to 81.8 mm (3 /32) in 1989; the limit will further rise by 0.79 mm - (3/n in) each year until 1992 when the minimum legal size will be 84.1 mm. From May through !
October 1989, the lobster population in the Millstone Point area was sampled using wire pots set at threc , stations. Population characteristics of lobsters were examined and included the size distribution, sex ratio, *
. percentage of egg. bearing females (berried), incidence of culls (lobsters missing claws) and molting patterns. v < Orowth and movement were monitored, using recaptute data from our tagging studies.. Lobster larvae 1 studies were also conducted during the hatching season (May July) to quantify the number of larvac entrained through the plants' cooling water systems.
Catch per unit effort (CPUE) for all sizes of lobster caught during 1989 was 1.84 lobsters per trap haul, compared to 1,70 2.03 during prior 3 unit operations (1986-88); and 1.02 2.10 during 2 unit operations (1978 85). Legal CPUE of lobsters a 81.8 mm, the new minimum legal size, was 0.090 during 1989. This value was within the range of results from 1986 to 1988 (0.89-0.97) when the minimum legal. size was 81.0 mm. The 1989 value was lower than the range of results from 1978 to 1985 (0.110-0.1%). Legal catches have declined since 1978 and may be related to increased fishirq pressure. The mean size of lobsters caught during 1989 (69.9 mm) was within the range of values reported from 1986 to 1988 (69.5 70.2 mm) but smaller than values reported -during 2-unit studies (70.7 71.8 mm). Female / male sex ratio during 1989 was 0.79, compared to values reported from'1986 to 1988 (0.85 0.88). The 1989 sex ratio was within the range of values reported from 1978 to 1985 (0.79 0.97). The Twotree station continued to have a higher female / male ratio (1,08) than Jordan Cove (0.64) and intake (0.65), a ' trend observed since the study began. The size at which females became sexually mature during 1989 was similar to previous years; females began to mature betwecu 50 and 55 mm CL and all females were mature at sizes greater than 95 mm CL The percentage of berried females collected during 1989 (6.4 % ) was higher than percentages collected , 'previ6usly in this study (3.16.2%). The mean CL of berried females during 1989 (77.3 mm) was within the _ l' range of values reported from 1986 to 1988 (76.5 78.0 mm) and from 1978 to 1985 (77.0-81.2 mm). The ; l high proportion of sublegal size berried females caught in 1989 (85%), was within the range of previous l observations (52-90%). l l Lobsters that exhibited near molt conditions represented 3.1% of the 1989 total catch, which was within the range of values reported in 2-unit (2.5-6.4%) and 3-unit studies (2.13.2%). The average growth per molt during 1989 was 14.3% for all lobsters, slightly higher than in other 3-unit studies (12.813.9%), but whhin the range of growth values for 2 unit operations (12.114.4%). The proportion of culls (lobsters missing one or both claws) in 1989 comprised 12.2% of the total catch, i which was higher than other results reported from 1986 to 1988 (10.311.1%), but within the range of values ( reported from 1978 to 1985 (10.6-15.5%). l The number of lobsters tagged in 1989 (6,837) was within the range of values reported in both 3-unit (5,680-6.837) and 2 unit studies (1,4817,575). . The percentage of tagged lobsters recaptured in our pots during 1989 (19.2%) was lower than that observed in prior 3 unit studies (21.0-25.2%) but within the range of 2-unit studies (14.4-23.9%). The percent caught in commercial traps during 1989 (21.5 %) was greater than that observed in prior 3 unit studies (17.2 20.4%) and within the range of 2-unit studies (21.147.6%). Changes in the percentage of recaptures in our traps and commercial traps were related to a trap regulation l Implemented in 1984 which requires escape vents in commercial traps that allow escape of sublegal-size Executive Summary xi ;
l q lobsters; sublegal size lobsters comprisc over 90% of our total catch. Our traps do not mntain escape vents . . and retain a greater number of sublegal sized lobsters. -l Tag and recapture data collected during l989 indicated that 95% of the tagged jobsters recaptured in our . !
- pots were caught at the station of release, and 99% of all the tags returned by commerciallobstermen werc ,
from lobsters caught within 5 km of Millstone Point. The average straight line distance traveled by lobsters - caught in commercial pots was 1.% km duting 1989,which was shorter than the distance travelled in 1986- .; i 88 studies (2.64 3.16 km) but within the range of 1978-85 data (1,70-3.01 km). Some lobsters (32) traveled
> 75 km from MNPS and were caught in waters off Rhode Island, Massachusetts, and in deep water canyons offshore on the edge of the continental shcif. ,
Stage I lobster larvac accounted for 90"4 of the four larval stages of lobsters collected in samples of the 1 MNPS cooling water during 1989. More larvac were' collected at night during-1989, similar to results reported in three of the five sampling years since 1984. The mean density of lobster larvac was 0.70 per 1000 m3 of cooling water, within the range of densitics it:norted from 1986101988 (0.63-0.88) but higher than densitics reported in 1984 and 1985 (0.42-0.43). The utimate of total lobster larvae entrained, based on sampic density and total MNPS cooling water demand, was 393,955 for 1989 and was within the range of estimates reported from 1986-88 ' (3m,695-611,462) but- higher than values reported in 1984 1985 3 (79,511 138,820). { Our results indicate that more than 90% of the lobsters above the minimum legal size are removed by fishing. The catch of legal sized lobsters is highly dependent on the number of lobsters in the sublegal size class (lobsters one molt away from legal size). The changes observed in the abundance and population-characteristics of lobsters caught during 1989 were related to the increase in minimum icgal size and not ; i to power plant impacts. The fishery objective of increasing the minimum legal size during the next 3 years ! is to enhance recruitment and sustain the lobster resource;; larval producion should increase as larger i l proportions of berried females are able to spawn before reaching legal size. The estimated number of - lobster larvac entrained through the plants cooling water systems remained high during 1989 due to the -
- additional cooling water demand of Unit 3. The effects, if any, of higher 1stval entrainment.will not be apparent at the levcl of adult population for several years, when these lobsters grow to a size vulnerable.
to capture in our traps. Benthic Infauna Intertidal macrofaunal communities _wcre sampled at two stations potentially. impacted by MNPS operations (White Point WP and Jordin Cove JC)-and one reference station (Olants Neck ON). Sediment grain sizes over all stations ranged from 0.31 to 0.54 min and the percentage of silt / clay was . generally below 0.5% During 1989, sediments at WP and GN were not significantly different from previous years, while those at JC were significantly finer than those obtained during the 2 unit period. 1 Sampling intertidal beaches during 1989 yleided a total of 51 taxa and 4,311 individuals. Polychaetes numerically dominated infaunal communities at GN and WP, while oligochactes were most numerous at JC. Rhynchocoels was a dominant taxon only at GN and WP, and molluscs and arthropods only at JC, On an annual basis, community abundance and species number collected at GN and JC in 1989 were significantly different from some 3 unit and 2 unit years. Over the entire 3 unit period, neither abundance nor species number was significantly different from 2-unit values. Numerically dominant intertidal taxa in 1989 included , oligochactes, Scolecolepides viridis and Capitella spp, at JC, and rhynchococls, Leitoscoloplos fragilis and Paraonisfulgens at GN and WP. These Organisms have typically dominated h Sunit a'nd other 3 unit years. No long-term increasing or decreasing trends in the abundance of any t@.rically abundant taxon have occurred since 1980. In addition, there have been no significtmt changes 3a abundance of any dominant intertidal organism in the 3. unit period relative to the 2 unit period. The 1989 sampling did show lowered dominance of Hedisse diversicolor and S. viridis'at JC and increased dominance of P. fulgens and L. fragilis xil Monitoring Studies, i989 1
i i i and decreased dominance of rhynchocoels at GN and WP. Species diversity and numerical classification also ; reflected these shifts. The structure and abundance of intertidal communities during 1989 were generally similar to those observed throughout the mcnitoring studies at MNPS. Differences in community abundance and - composition among stations were consistent with previous years and are believed due to natural factors, not j to power plant operations. Temporal changes in the dominance of some taxa were evident in 1989 and were likely due to changes in local sedimentary characteristics. At present, the exact cause for the sedimentary a changes in not known. Subtidally, infaunal communities were sampled at thrce potentially impacted (Effluent EF, Intake-IN and Jordan Cove JC) and one reference station (Giants Neck GN). Subtidal sediments in 1989 ranged from fine to coarse sands with finest sediments found at JC and coarsest at EF. Silt / clay values ranged from 1 to 15%; lowest values occurred at EF and highest at JC. At 3 of 4 stations, sediments in the 3 unit period were significantly different from those obtained during the 2 unit period. Infaunal sampling yielded 193 taxa and 33,688 individuals. At all stations, polychactes were most numerous, in terms of species and, except at EF, this group also dominated in terms of individuals, Relative to the 3 unit period, oligochaetes increased in dominance at EF and decreased at JC, At IN, arthropods decreased in dominance during 1989. Community abundance and number of species at all. stations have shown no long term trends since 1980. In addition, IN.was the only area where these community parameters showed a significant difference between 3-unit and 2 unit periods. Oligochaetes and Aricidea catherinae were the most dominant subtidal taxa in the Millstone area during 1989. Also abundant - were Protodorvillea gaspeensis (EF), Lumbrineris tenuis (JC) and Polydora quadrilobata (1N) Relative to the
- 2. unit period, the major changes in dominance structure were as follows: oligochacte dominance increased ,
at EF while that of Po&cimes crimius and A. catherinae decreased; at JC, dominance of L. tenuis and Nucula i proxima increased; at IN, densities of N. prarima and Leptocheirus pinguis were have been higher in the 3
- unit period. At all stations, Afediomastus ambiseta showed large decreases in abundance in 1989, similar to 1988. Cumulative curves, species diversity and numerical classification analyses reflected the community shifts observed at EF, IN and JC stations.
Subtidal communities during 1989 exhibited both natural and power plant related shifts in abundance and composition. Reduced abundances of Afediomastus ambiseta and Leptocheims pinguis were evident at all , stations in 1989 and occurred independent of power plant operations. Direct power plant impacts were evident at 3 of the 4 sampling stations. At IN, sampling in 1989 indicated continued recovery of this community from impacts which occurred during construction of the Unit 3 intake structure and associated l ' dredging. The EF and JC communities showed impacts that were identifiable after Unit 3 start up. At EF, sedimentary changes due to scour produced by the 3-unit discharge has been accompanied by an infaunal community shifts in abundance and dominant taxa. At JC,1989 data showed continued recovery from the- , siltation of this area, which occurred immediately after 3-unit operations began Because of impacts related - to this siltation event, continued study of this area is necessary before any impacts associated with other operational factors can be fully addressed. l l Rocky Intertidal Studies - _; Rocky shores in the vicinity of MNPS have been sampled since 1979, as part of an ongoing environmental ! monitoring program to assess the effects of construction and operation of the power plant. Rocky intertidal studies include qualitative algal sampling, abundance estimations of intertidal organisms that comprise rocky shore communities, recolonization studies, and studies of tagged populations of Ascophyllum nodosum. ! L Executive Summary xill
i e i b The local intertidal flora, represented by monthly qualitative algal collections at rocky shore sampling sites in the present sampling year (Oct.1988-Sep.1989), included 121 species; 56 spccles were reds (47%),32 species were browns (26%), and 33 species were greens (27%), in the 3-unit operational period to date (Mar.1986 Sep.1989),141 species have been collected (48% reds,25% browns,27% greens), and the total-flora sir.cc 1979 included 159 algal species (47% reds, 25% browns, 28% greens). Species that were identified during 2 unit operation, but not during 3-unit operation to date, were not consistent components of the flora. The similarity of species composition among periods suggested that overall floristic changes have not occurred. Rocky intertidal communities at most sites in the Millstone area were typical of those studied throughout I New England; patterns of zonation, species composition, and seasonal abundance at MNPS study sites were : similar to those reported from comparable rocky shore areas. High intertidal surfaces were mostly bare, except for seasonally transient populations of barnacles and ephemeral algac. Mid intertidal surfaces were typically covered by a fucold canopy over a barnacle understory. Low intertidal surfaces were dominated by Chondrus crispus. Differences that exist among stations were attributed primarily to different degrecs of exposure to prevailing winds and waves, and to factors (e.g., slope, stability of substratum) unique to each site, , At Fox island Exposed (the station nearest the MNPS discharge), the community continued to be influenced by the thermal plume. Low intertidal areas, exposed to clevated water temperatures for 910 hours cach tidal cycle, were still dominated by Codium, Ulva, Enteromorpha, and Polysiphonia. Some algae commonly found in law intertidal areas at FE (e.g., Gracilaria, Agardhiella) were typical of collections made from the quarry cuts; seasonal occurrences of many species at FE showed temporal shifts like those seen in quarry collections. .However, middle and upper intertidal areas at FE were exposed to clevated , temperatures for a shorter time, and maximum abundances of Fucus and barnacles that occurred in 1989 resembled those that occurred prior to the opening of the second quarry cut. , Recolonization of intertidal organisms, following removal of attached biota in September 1986, continued to be monitored in 1989. - Recovery of the simple high intertidal community (i.e., barnacles, cphemeral algae) was considered complete after less than six months. Recovery of the mid intertidal community,. represented by Fucus and barnacles, took 18-24 months. Recovery of the low intertidal community, typically involving re-establishment of Chondrus populations, was slower, and was not yet complete after 42 months. Patterns of recolonization following the September 1986 denuding (during 3. unit operation) were similar ~ to those observed following the September 1981 denuding (during 2-unit operation), although rates of recovery for Fucus at all stations were higher in the 3. unit period than in the 2-unit period. Ascophy/ hun populations in the MNPS area continued to be monitored in 1989, and higher growth of this alga at the station nearest the discharges (FN), relative to that at stations farther away, was attributed to elevated water temperaturcs. The 1988-89 growing season represented the first time that all three units operated continuously through the peak growing period; average tip length at FN in 1989 was the highest seen at any station since sampling began. As in previous years, Ascophyllum mortality (l.c., loss of tagged plants and tips) was not related to proximity to the power plant discharges. Marine Woodborer Studies Ircal fouling communities and woodborers exhibited high spatial and temporal variability at sampling stations in the Millstone area. The fouling of panel surfaces during 1988-89 was highest at F1 and BP and lowest at GN. Thirty one species have accounted for more than 70% of the annual surface fouling since 1979, and most of the species exhibited strong seasonal periodicity. For example, Cryptosida pallasiana and -1 I Schizoporella errata were most abundant during the Aug Feb and May-Nov exposure periods. Coverages of Mytilus edulis and Laminaria saccharina peaked during Nov-May. Balanus baianoides and D. crenatus peaked - 1 l xiv Monitoring Studies,1989 ) l l
j ._ in Feb Aug. Cover of foulers at EF and GN decreased during 3 unit opcration, relative to 2-unit operation, and was due to reduced cover of barnacles. At EF, the decrease of barnacle cover was caused by severe degradation of panel surfaces by shipworms. Fouling covers increased during 3 unit operation at FI because of the increased abundance of Cryptosula pallasiana, Balanus crenatus, and B. balanoides. Woodboring species in the vicinity of Millstone include Tcredo navalis T, bartschi, Limnoria spp, and Chelura terchums. Terrdo navalis was most abundant in May Nov and Aug Feb, and at WP and GN. Teredo bartsch/ was most abundant in May Nov, but was only collected at EF. Limnoria spp and Chclura screbrans were most abundant in May Nov, and at WP and GN. Wood loss in 1988-89 was primarily due to T. navalis and T. bartschi. Limnoria spp, and Chclura terebrans generally accounted for less than 5% of total wood. loss. During 3 unit operation, abundance of T. navalis was significantly higher at WP and lower at GN, than during 2-unit operation. Abundances of Limnoria spp, and Chclura terebrans were signiticantly lower during 3 unit than during 2 unit operation at FI, WP, and GN. Abundance of Tcredo bartscht was significantly higher at EF during 3 unit than during 2-unit operation. This increase was associated with more consistent thermal regimes within the quarry during 3 unit operation. j Settlement of Tcredo navalis occurred primarily in the May Oct exposure period. Densities at 500 m and 1000 m sites were higher than those at other sites, suggesting enhanced settlement near the discharge. b)wer densities at 100 m and 200 m sites, compared to 500 m and 1000 m sites, were caused by high current velocities resulting from the 3-unit /2 cut discharge. No Teredo barischiwere found outside the quarry during the 1988-89 sampling year, despite the increased abundance of this species within the quarry, Laboratory studies suggested that T. banschi might establish isolated summer populations in shallow areas, which have summer temperatures above 20*C for extended periods. However, low winter water temperatures below 5'C may be preventing survival of these populations in winter, making their persistence very unlikely. 1 Seagrass ! Ec1 grass, Zostcra marina, is a conspicuous marine angiosperm, inhabiting marine soft bottom areas up to 10 m in depth, in the Millstone area, this plant has undergone large fluctuations over the last fifty years, ! reaching nuisance levels in the nearby Niantic River until the wasting disease of the 1930's caused the near disappearance of this plant. Slow recovery occurred in the 1950's and 1960's, and in the early 1970's, j NUSCO initiated studies of local eclgrass beds to determine the relationship between MNPS operations and i local increases la eclgrass. Objectives of the present study were to characterize the local celgrass population j and determine the extent to which this plant might be affected by MNPS operations, j During 1989, three stations were sampled monthly from June through September :md the celgrass population characterized in terms of shoot density, plant length and biomass. Along with ecigrass samples, sediments were analyzed for grain size and silt clay content. Grain sizes observed during the current sampling year were similar to those observed in past years with coarsest grain sizes occurring at JC and l finest sediments present at NR. Silt clay and organic content (%) over this year were highest at NR and lowest at WP. Average number of celgrass plants was highest at JC, lowest at NR and intermediate at WP. Shoot length was greatest at WP and least at JC. Highest standing stock occurred at WP and lowest at NR. Executive Summary xv 1
i i A distribution study performed in 1989 to map the location and extent of celgrass cover within the. Niantic River, indicated that extensive beds were present in 1989 suggesting a degree of recovery from population losses noted in 1986-87 surveys. Comparisons were also made between mapping surveys - performed in Jordan Cove in 1974 and in 1985, and indicated consisteng.of eclgrass distribution. Eclgrass populations in the Millstone area exhibit spatial and temporal variations in population characteristics, typical of this marinc plant through New England. Differences among stations are probably. the result of natural differences in the physical characteristics of our stations. In terms of temporal variation, the eclgrass populations at JC and WP since 1985, and at NR since 1987, appeared stable and. , predictabic, reflecting the consistent sedimentary environment. Within the Niantic River, decreases in eclgrass during 1986 88 have been attributed to disease and decreased water quality. To date, and particularly during 1989, there have been no changes in local celgrass populations that could be attributed to oj. station of MNPS. [ 1 i 1 L l y i i xvi Monitoring Studies,1989
.u Contents l
Intr 0 duction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 'l' l l Winter Flou nder Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Fish Ecology St udies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81' Imbster Population Dynamics ................................... 121-Ben thic Infa u na . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 - Rocky Intertidal Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 Marine Woodtxar Studies ..................................... 221-Seagrass .................................................. 245 s l i 6 ( i i
?
l l' s
f Introduction P separate shoreline intakes located on Niantic Bay The Millstone Nuclear Power Station (MNPS) (Fig. 2). is located on the north shore of bmg Island The intake structures, typical of . shoreline installations, have coarse bar racks and Sound (LIS) in Waterford, Connecticut (Fig.1). traveling screens. The cooling water from Units The MNPS complex consists of three operating 1,2 and 3 (nominally heat to a maximum of 13.9, nuclear power plants. Unit 1, a 660-MWe boiling , 12.7 and 9.5 *C., respectively, above ambient) water reactor, began commercial operation , November 29, 1970. Unit 2, an 870 MWe flows fr m separate discharge structures into an r b nd ned granite quarry. The water, which is pressurized water reactor, began commercial . operation in December 1975. Unit 3, a about 11 *C warmer than ambient when all three- , units are operating near maximum capacity, exits 1150-MWe pressurized water reactor, began commercial operation on April 23, 1986. All the quarry through two channels (cuts) equipped with fish barriers where it mixes with LlS water, three units use once through condenser cooling water systems. The rated circulating flows for A history of MNPS power production and cooling Units 1, 2 and 3 are 26.5, 34.6 and 56.6 m'/s, water demand is presented from 1985 through 1989 in Figure 3. respectively. Cooling water is drawn from depths greater than 1 m below mean sea level by - l
\'5 ##4 W ver 0
$m E -
r . p & '
~
MN Jordon Hiontic Bay Cove White Giants Neck Point g twetree Chonnel Diack Q Point Long Island Inund eartiett Reer Fig.1. The area where biological monitoring studies are conducted to assess the errects or the operation or the Millstone Nuclear Power Station. Introduction 1
y. unstone Nwear und 3 Stat % i Jordon i net . Cove q p 2 g,;g 6schoron , , intches 1-( ...
<,3 $
~= /\ ,
b 8' , 0 .. second cut "9 # Niantic Boy
- 1.otree .
Channet Fig,2, location of the MNPS showing each unit's intake and dieharge, the quarry and the two cuts, i
-i moo iso.
'T5' M "'
n P!*yl l j "" " Il 7[f ice r/ im I (
'(
ism. p p { r
-1 4
fi 1 ( r l l p I n. w 1 ' l ' l iem so l r ' [ oco
} , n f 0- 0 ma ma Fig. 3. MNPS operating conditions, station power levels (MWe) is plotted on left and cooling water usage (m3/s, enu) is plotted on right from January 1985 through December 1989; vertical line indicates Unit 3 commercial operation on April 231986.'
2 Monitoring Studies,1989
i V The effects of MNPS operation on local changes beyond those that would be expected to_ l marine blota result from using large volumes of occur - naturally, and if so, to evaluate the . cooling water from LIS. The potential impacts ecological significance of these changes. The ' include impingement of organisms on the intake scope of the monitoring prognms has increased travc11nf,. screens and entrainment of eggs and considerably since they began in 1968 to provide i larvae through the cooling water systems. The the representative data and scientific basis needed > impacts associated with impingement at MNPS to assess potential environmental changes using + are mitigated at Units 1 and 3 because slutceway state.of the. art methodology, t
-(
systems in their intakes return impinged 7 In addition to the monitoring studies, several , organisms to LIS (NUSCO 1986, 1987). Marine communities in the discharge area may also be hydrographic and hydrothermal studies have been i affected by the thermal effluent and by chemicals conducted since'1%5 to determine the general
- added to the cooling water (l.c., chlorine, boron, hydrographic nature of waters surrounding MNPS 1 i
heavy metals). Furthermore, the volume of and to verify the shape and extent of the thermal cooling water discharged during 3. unit operation- plume during 3. unit operation (NUSCO 1983). may cause sediment scour and' thereby affect . Strong tidal currents are an important i benthic communities inhabiting the discharge . hydrographic feature of the area around MNPS. area. In particular, flow . from Niantic ' Bay through Twottee Island Channel forms a strong current The MNPS monitoring programs sample an (11.5 knots) past MNPS and _ allows the heated approximately 50 km2 study area 2 km -west of effluent; water to rapidly mix with- cooler LIS ' > Black Point,2 km south of Twotrec Island and 2 water (NUSCO-1975a). Within 1,100 m of the km east of White Point (see Fig.1). The discharge channels, the surface water temperature objectives of the MNPS monitoring programs are of the thermal plume cools to within 4'F (2.2*C)- e to characterize the various estuarine communities above -ambient; beyond _this distance the in the vicinity of the Station and determine configuration and extent of the plume are highly + whether the operation of MNPS results in dynamic and vary with tidal currents (Fig. 4).
,. m i u m' u u ., . m m. . ~
s g1 ttg
, '= .= % 4 l
I' '! ( \u
\k f j 3 p V .
\ t 1 .. .
L.Eb.4. h V [,- ( TN 'hd .g "N el'.-l- '
-=
l .
'= %
*- *~. .
Fig. 4. tocations of selected 3-unit thermal plume isotherms during four tidal stages. Clockwise from upper left: isotherms at low slack, maimum ebb, malmum flood and high slack (rrom NUSCO 1988). Ir.troduction 3
^ 35- Weekly over0Q 01 in he (...) Ond ef flu l(_)
O 30 D 2s.
) - '
us.me
,e z
9 n l\ E h io / $~ of (bY ?.,W. /\.Ii!l\ j!\ '!\ l't; *.l\ i,,, \. :.j\ ~~'l'h lY
- - s '. * *
- e ,.
( : i *n * . tY s .. g i .
./ g!\ . < ' i , .
' t
\ i \l . _l_ \} y _ \l.
t, b t _ _ \_! q' 'el ' Awooe yg _ _3,i. 4 _ ./__x__ _ _ _ &I t _ _ _e /e'__f_.>
=m- ,
-o JANi976 JAHi978 JAN5980 JANi982 JANi984 JANi986 UANiDBB UANi990 m 3b Weekly overage at NUEL. dock (.. )
u 30 v Q 2s , Awee.
% 20 ~ ~f~. ~ .p- ;
,. W ~ fg~ ~ f. - ~,.$, ~ f. '. ~ .f. ~ ~.r\, ~ f( ~ .p, ~. ~ ,. ~ . ~6~ l L .g h 1b i s. p , ,.
\
, g , .r
'\ .
..,'i\'i!.\ y e ,
k sn i .' \ '\ o \ '
.!\
~ t
* \ i** ' '1 \l * ** * \
~\ y' \l ') *~^--P~~~~f*~-=*-1-~'~~ \ll ? '.l V ~l s\} 'il < :7,
' t
? % '. '\le 2 y 0 '- ~-
- JANI976 YANiP78 dANi980 dANi982 dANi984 JANi986 JANi988 JANI990 m 35 weekly average at M; joy dock. Niontic Rwer (...)
U 30 v g 25 A.
~~N"~*~"I~~~~"**,"*
i
%* 20 , ~ 44 ~ ~!*Y ~ ~" ~ ~ '\ j' , g
~d' '~ -~* ~ i ~ ~ l-.7's.,' s~ T'
- ~ 0 ~ ~ *i t'a 'A
's . ' * /
e [i /t
- 8 15
- i . . ;
- I 'g ; . .
i
.'k
',*f ,k ' ,'j 'f I
~
h 10- ; .I . .
.' i . . ** .'
.t I- 'g '
,' '. .* .i s a
'y ',* ,q t:
1 ' t . s y, , .* e'. ; i .' si .
*' 4 Amage hO '~~ ~ ~Y~ ~ ~~E~~,~~!-~A-~ ~ ~ ~ Y ~ ~ N _ 's . * "[,*
l
-5 JANI976 JANi978 JAH k 980 JANi982 JANi984 JANi986' JANi988 JANi990
^ 35 ' Weekly ovetoge at White Point (.. )
U v 30 2b g Avevo,e
% 20 ' ~;'~ ~ ~'
~ ~f' ~ Y ~~z'~ y ~ ~~%~ ~~ ~ ~ ,y ~ g " *,;*' ;
kc is *
,.'s . '
\ : ,
- t, *
. \
',.t.
> ', , - r '
g f1 10 -. ,,i , . t > ,? s t . xe .. y %j */ i [ Average
-__',,'__\__.t!__'a.,-.
- 1 . ,e 9
o o . 4 _ ,L _ _, f r/ _ _ *_ _ _ _ _ _ _ ' .
' uiaimum intee
-5 JANi976 JANi978 JANi980 JANi982 JANi984 dANI986 JANi988 JANI990 Fig. 5. The weekly awrage water temperatures at the MNPS intake, emuent, NUEL dock, Mijoy dock (Niantic River) and White Point plotted with the annual minimum and maximum intake tempenitures averaged over the entire time series.
4 Monitoring Studies,1989
I Water depth in the study area varies, reaching .1975b. Water quality. Pages 5.11 to to 15 m in Twotrec Island Channel and up to 20 5.8-3 in Summary Report, Ecological and i m . In areas southwest of 'fwottec Island. Hydrographic Studies, May 1966 through } Throughout the area the bottom is generally December 1974, Millstone Nuclear Power , composed of fine to medium sand but includes Station. t some rock outcrops and muddy sand in the nearshore zone (NUSCO 1975b). Water . 1983. Millstonc Nuclear Power Station t temperatures measured at 4 shore-based sites Unit 3 Environmental Report, Operating l ranged from .3 to 25 C; the watt temperature of License Stage.- Vol 14. ; the discharge, measured at the qua 'ry cuts, ranged
- from .1 to 35"C (Fig. 5). Salinity 1, nges from 26 . 1986. The effectiveness of the Millstonc :
to 30 % (NUSCO 1975b). Unit 1 sluiceway in returning impinged ! organisms to long Island Sound. - 18 pp. [ The picsent report provides results of the 1989
- studies conducted during 3. unit operation. The .1987. The effectiveness of the Unit 3 fish !
1989 data are compared to results from previous return system 1987, 20 pp. years during the 3. unit operational period (1986-1988) and to baseline data collected during 2 unit operation to assess the impacts of Millstone Unit 3 on local marine organisms. This report also satisfies ecrtain license and permit conditions stipulated by the Connecticut Department of Environmental Protection and the Connecticut Power Facility Evaluation Council. The report , contains a separate section for each continuing monitoring program. Report periods for each section vary and are based on biological considerations as well as report requirements to regulatory agencies. The report period for the Rocky Intertidal studies is from October 1988 through September 1989 and for lobster Population Dynamics from May through October 1989. Report periods for Winter Flounder and Fish Ecology studies are from January through December 1989 and June 1988 through May 1989,- respectively. Data reported in the Benthic infauna section are from samples collected quarterly: September, December 1988, and March, June 1989. Exposure pancis are set during four i exposure periods in the Marine Woodborer studies, and results in that section include data l summarized from May 1988 through August 1989. l Results of the Scagrass studies are from surveys conducted from May through September 1989. References Cited l NUSCO 1975a. Hydrography, Pages 3.11 to 3.61 in Summary Report, Ecological and Hydrographic Studies, May 1966 through December 1974, Millstone Nuclear Power Station. Introduction 5
n Contenis Winter Flounder S tudies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 In trod u c tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Sampling programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Ad ult winter flounder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Larval winter flounder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I 1 Post larval age 0 and age-1 winter flounder . . . . . . . . . . . . . . . . . 12 Indices of abundance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Relative annual abundance of adults . . . . . . . . . . . . . . . . . . . . . . 14 Absolute abundance estimates . . . . . . . . . . . . . . . . . . . . . . . . . 14 Spawning stock size and egg production . . . . . . . . . . . . . . . . . . . 15 Abundance, growth, and mortality oflarvae . . . . . . . . . . . . . . . . . 15 Abundance, growth, and mortality ofjuveniles in summer . . . . . . . , 16 Abundance ofjuveniles in fall and winter . . . . . . . . . . . . . . . . . . 16 Stock nnd recruitment relationship (SRR) . . . . . . . . . . . . . . . . . . 17 MNPS impact assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Imal entrainment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Winter flounder stochastic Results and Discussion . . . . . . . . . ...........................23
. . . population dynamics model . . . . . . . . . . 20 Adult winter flounder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . 23 Relative annual abundance . . . . . . . . . . . , . . . . . . . . . . . . . 23 Absolute abundance estimates . . . . . . . . . . , , . . . . . . . . . . , , , 25 Spawning stock size and egg production . . . . . . . . . . . . . . . . . . . 27 Larval wmter flounder . . . . . ............................29 Abundance and distribution , , . . . . . . . . . . . . . . . . . . . . . . . . . 29 Growth and development . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 M ortality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Post larval age-O winter flounder . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 l
Abundance during summer . . . . . . . ........,........40 G ro wt h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4 l M ortali ty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 6 l Abundance during late fall and early winter . . . . . . . . . . . . . . . . . 47 . Age 1 juvenile winter flounder . . . . . . . . . . . , . . . . . . . . . . . . . . . . 49 Abundance during the adult spawning season . . . . . . . . . . . . . . . . 49 Comparisons among life stages of wmter flounder year classes . . . . . . . . . 51 Recruitment and year-class strength . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Stock recruitment relationship (SRR) . . . . . . . . . . . . . . . . . . . . , . . 55 Wint:. flounder population dynamics model . . . . . . . . . . . . . . . . . . . . . 57 Model input data and run modes . . . . , . . . . . . . . . . . . . . , , . . 57 Model calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , 5 8 Detemiinistic stock assessment . . . . . . . . . . . . . . . . . . . . . . . . . 59 Stochastic simulation of the Niantic River winter flounder stock. . . . . 59 MNPS impact assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 Estimates oflarval entrainment at MNPS . . . . . . . . . . . . . . . . . . . 62 Effect of entrainment on the year class . . . . . . . . , . . . . . . . . . . 62 Probabilistic risk assessment (PRA) of larval entrainment . . . . . . . . 63 Con cl u s i on s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 S ummary . . . . . . . . . . . . . . . ...............................68 References Cited . . . . . ........ . .. .....................70 Appendix . . . . . . . . . . . . . . .. ... . ............... .......76 Scaling factor for multi age recruitment . . . ....................76 Monality through the first year ...........................76 ,
Winter Flounder StudicS Introduction 1963) Many adult fish stay in estuaries following spawning, while others disperse into deeper waters. The abundance of winter flounder (Pseudopleur. By summer, most individuals leave the warmer shal-onccles americanus) in the Greater Millstone Bight low waters as their preferred temperature range is 12 has been evident from the beginning of environmental 15'C (McCracken 1963). However, some remain studies carried out by Northeast Utilities Service within estuaries and often avoid temperatures above Company (NUSCO) since 1973 at the Millstone 22.5'C by burying themselves in cooler bottom sedi. Nuclear Power Station (MNPS). The species has ments (Olla et al.1969) Winter flounder are sight dominated the trawl catch of demersal fishes in the feeders and are usually active only during the day, feed. area,it has been the most numerous fish impinged on ing on a wide variety of benthic invertebrates and the traveling screens of the cooling water intakes at algae. Additional details regarding winter nounder life MNPS, and large numbers of its larvac are entrained history, physiology, behavior, and population dynam-through the cooling water system each spring. Un- ics may be found in Klein-MacPhee (1978), like most marine fishes, the winter Dounder is a product of local spawning with geographically A major goal of the winter flounder studies by isolated stocks associated with individual estuaries NUSCO has been to provide supporting data and n (Lobell 1939: Perlmutter 1947: Saila 1961). There- scientific basis for the long-term assessment of the fore, impacts due to the operation of MNPS, partic. Niantic River winter flounder stock, which is primar-ularly entrainment of larvae through the cooling water ily subjected to annual losses through the entrainment system, are of greater concern for the winter flounder of larval fish at the cooling water intakes of MNPS. than for other local species that are comprised of Although understanding interannual variability is im-stocks having much greater geographical range, portant to satisfy short term assessment demands, the most significant changes in fisheries seem to occur The winter Counder ranges from Labrador to Geor- on a much longer time scale (Cushing 1977: Steele et gia, but is most common in the central part of its dis- al.1980). Therefore, the development of long term tribution (Scott and Scott 1988), which includes assessment capabilities has remained the ultimate Long Island Sound (LIS). Most adult fish enter natal research goal of NUSCO's winter flounder studies estuaries in late fall and early winter and spawning since their inception in 1973. The general approach occurs in late winter and early spring. Females begin has consisted of a combination of sampling programs to mature at age 3 and 4 and males at age 2, and aver- and analytical methods designed to provide a prelim-age fecundity is about 560,000 eggs per female, inary short term assessment capability and, ulti-Eggs are demersal, hatching in about 15 days, and the mately, a long. term assessment tool in the form of a larval stage lasts about 2 months, both depending comprehensive computer simulation model. upon water temperature Smalllarvae are planktonic and most remain in natal estuaries, although many in- 'The present report summarizes and updates the win-dividuals may be carried out into open waters by tidal ter flounder data base previously reported (NUSCO currents (Smith et al.1975; NUSCO 1989). Some 1989) with data collected in 1989, presents new pop-of these larvae may return to the estuary on sub- ulation and larval entrainment estimates, and dis-sequent incoming tides, but many of the rest are dis- cusses the most recent assessment results based on persed away from the area. Larger larvac maintain stock and recruitment theory, in addition, results of some control over their position by vertical move- an application of the winter flounder population dyna-ments and also may spend considerable time on the mics model to stock assessment is presented here for bottom. Following metamorphosis, most demersal the first time. This assessment of the Niantic River juveniles are found in shallow inshore waters. Im- stock takes into account current exploitation rates, mature yearling (age 1) winter flounder become photo- stock size relative to the Connecticut winter flounder negative and though many remain within the commercial fishery, and hypothetical levels of entrain- l shallows, they are usually found at greater depths than ment. Work on the hydrodynamics component for age O young of the year (Pearcy 1962: McCracken larval dispersal and entrainment (Dimou and Adams Winter Flounder Studies 9
1989) for the final simulation model is continuing at ure 1, including the seasonal duration of sampling and the Massachusetts Institute of Technology (MIT) and timing relative to the annual life cycle of local winter is not capected to be completed until the summer of flounder. Brief descriptions of field methodologies 1990. used in these programs follow. Materials and Mcthads Adult winterflounder Sampling programs Sampling methodology for the adult winter floun-der spawning surveys in the Niantic River have Several sampling programs (e.g., Niantic River remained relatively consistent since surveys began in - adult and larval surveys, age-O survey) provide data 1976 (NUSCO 1987). _ Since 1982, each survey specifically to assess the impact of MNPS on the win- started after ice out in the river in February or early ter flounder. Some data, including those from the March and continued through early April, when the trawl monitoring program and ichthyoplankton mon- proportion of reproductively active females finally itoring at MNPS and in Niantic Bay come from year- decreased to less than 10'k of all females examined for round sampling of the entire kical fish community, of 2 consecutive wecks. - For each survey, the Niantic which the winter flounder is an important component. River was divided into a number of stations (Fig. 2); Data for the latter sampling programs only from spe- since 1979 no sampics have been taken outside of the cific montns or for specific life-stages are used in the navigational channel in the lower portion of the river analyses presented in this report. Much of the in- because of an agreement with the East Lyme-Water-formation given in NUSCO (1987), which sum- ford Shellfish Commission to protect the habitat of mariied various life history studies of the winter the bay scallop (Argopecten irradians). Winter floun-flounder, was used in various assessments for this re- der were collectal on several days of each survey week port. Sampling programs that contributed data to the using a 9.1 m otter trawl with a 6.4 mm bar mesh Niantic River winter flounder studies are shown in Fig- codend liner. De fish caught in each tow were held 5 l Trawl Monttonng. O stations , m 'NA%NN'\%%N%%%1 4 bNN%%MNN%%NNN%%%1 Age 0 Juvenile Survey 3 I b%%%\%%N%i ~ lehthyoplankton Monttonno. 2 stations l ! 2 b%%%%%5%ws Niantic River Larval Survey 1 IK%%%N1 Niantic River Winter Flounder Survey l l FlMIA IMI J lJ lAISIOIN ID IJlF lMIAl L, Year 0 J , Year 1
- 1. February April sampling for adults and juveniles throughout the Niantic River
- 2. February June larval sampling at three stations in the Niantic River
- 3. Year round monitoring of allichthyoplankton at MNPS discharge and in Niantic Bay
- 4. May September sampling of Age-Ojuveniles at two stations each in Niantic River and Bay S. Year round monitoring of all benthic fishes at six stations near MNPS Ouvenile data come from two stations in November, four in December and six in January through April)
Fig.1. Currem sampling prograrm contributing data for computation of winter flounder abundance indices (hatched area show months from which data were used in this reporth 10 Monitoring Studies.1989
l l 1 reproductive condition of larger winter flounder was . determined either by observing eggs or mitt or, as sug- l gested by Smigielski (1975), noting the presence- , (males) or absence (females) of etenil on the caudal l peduncle scales of the left side. Each healthy fish lar- ; Niantic get than 15 cm (1977 82) or 20 cm (1983 and after) i was marked with a number or letter made by a brass ; A 54 River brand cooled in liquid nitrogen and then released. The a brand was changed each week and recaptured fish were noted and remarked with the most current brand (n use. 9 Larvalwinterflounder i Entrainment sampling (station EN) for winter floun-der larvac has been conducted at the MNPS discharge North 52 since 1976 (Fig. 3). Winter flounder larvac were collected at the discharge of Units 1 or 2 using a 0 1km gantry system to deploy a 1.0 x 3.6 m plankton net 51 st of 333 pm mesh. Four General Oceanics (GO)- flowmeters (model 2030) were positioned in the mouth of the net to account for horizontal and vertical flow variation; sample volume was determined by 4 averaging the four volume estimates from the flow-meters. Generally, the net was deployed for 5 to 6 min (filtering about 400 m3), but this varied depen-ding upon factors such a's the number of circulating-pumps in operation and tidal stage. Samples were collected during both daylight and at night once per week in February and June, and during 4 days and nights per week from March through May,- All samples were preserved with 10% formalin.
' A 60-cm bongo sampler has been used to collect
[ winter flounder larvac in Niantic Bay at station NB ( since 1979 and in the Niantic River at stations A, B, and C since 1983 (Fig. 3). The bongo sampler, weighted with a 28.2 kg oceanographic depressor, was Fig.2. Location of stations sampled for adult winter - fitted with 3.3-m long nets and was towed at approx-flounder during the spawning season in the Niantic River imately 2 knots. Net mesh size was 202 pm in Feb-during 1989, ruary and March and 333 pm during the remainder of the season. Volume of water filtered was determined using a single GO flowmeter mounted in the center of l in water filled containers aboard the survey vessel cach bongo opening. A stepwise oblique low pattern before processing. For all survey years, at least 200 was used with equal sampling time at surface, randomly selected winter flounder were measured to mid depth, and near bottom. The length of tow line the nearest mm in total length during each week and,L necessary to sample the mid-water and bottom strata: since 1983, all specimens larger than 20 cm were was based on water depth and tow line angle measured measured and sexed ' Fish not measured were clas- with an inclinometer. Tow duration was 6 min at sified into various length and sex groupings; at stations A, B, and C (filtering about 120 m3) and 15 : minimum, all winter flounder examined can be class- min 'at station NB (filtering about 300 m3), ified as smaller or larger than 15 cm. The sex and Winter Flounder Studies - 11 1
I l 1KM l
\ }'{
k 1 MI NIANTIC RIVER w NIANTIC BAY EN
- 5 h
() (' O Nq Fig. 3. Location of stations sampled for larval winter flounder in 1989. The sampling schedule was based on information 100 ml. All ichthyoplankton samples were preserved from previous years and was designed to increase with 10% formalm. ' efficiency in data collection and to reduce various sampling biases (NUSCO 1987). At NB, single day Post larval age 0 and age 1 winterflounder and night tows were,mado during February and at least > once a week in March through the end of the larval Surveys of post larval young of-the year winter winter flounder season. Sampling at the three Niantic flounder have been made in the Niantic River since River stations started on February 10 in 1989. From 1983 (NUSCO 1987). Station LR has been sampled the start of sampling through the end of March, every year and WA since late 1984; two Niantic Bay single daytime tows at each station were made twice stations (RM and BP) were established in 1988 (Fig. weekly within 1 hour of low slack tide. During the 4), The river stations were sampled weekly from late first 3 weeks of April, single day and night bongo May through late September during daylight from tows were made twice weekly, Day samples were about 2 hours before to I hour after high tide so collected within I hour of low slack tide and night sufficient (ca.1-1.5 m) water depth was present at samples during the second half of a flood tide, each station. Stations in the bay were sampled before During the remainder of the season and until the or after those in the river depending upon time of disappearance of larvae at each station, tows were high tide in relation to sunrise or sunset and, thus, made twice a week only at night during the second were occupied at varying tidal stages. Sampling in half of a flood tide. At the three river stations, jelly- 1989 ceased at BP in August and at RM in September . fish medusac were sieved (1-cm mesh) from the after no young were taken for 2 consecutive weeks. , sample and measured volumetrically to the nearest 12 Monitoring Studies,1989
l 1KM
\
O! , 1 MI NIANTIC RIVER W LR RM NIANTIC BAY BP o Fig. 4. Location of stations sampled for age O winter flounder from May through September in 1989.
, Age-0 winter flounder were collected with a 1 m beam Catches from the trawl monitoring program were trawl having interchangeable nets of 0.8 ,1.6,3.2 , used to calculate an abundance index of juvenile and 6.4 mm bar mesh, in late June of 1983, two winter flounder during fall and winter (see the Fish tickler chains were added to increase catch efficiency, Ecology section of this report). Because data on as older and larger young apparently were able to juvenile fish abundance were available from about avoid the net without them (NUSCO 1987), in May of their birth year into April of the following 1983, triplicate tows were made at LR using nets of year, juvenile indices were referred to as age-0 or l increasingly larger mesh as the season progressed. age 1, depending upon the time period and source of Beginning in 1984, two nets of successively larger the data. In addition to the trawl monitoring pro-mesh have been used during each sampling trip. A gram, juvenile winter flounder, mostly age 1, were l change to the next largest mesh in the four net se- taken along with adults in the annual Niantic River l quence was made when fish had grown enough to spawning stock surveys. Fish were processed simi-become susceptible to it; the larger meshes reduced larly as adults, although none were sexed or branded.
- the amount of detritus and algae retained. At each When these juveniles were abundant, only a sub-l station, two replicate tows were made with each of sample of 200 or more fish were measured each week.
I the two nets in use, which were deployed in a random l order. Tow distance was estimated by letting out a Indices of abundance I measured line attached to a lead weight as the net was hauled at about 25 m per min. The length of each Annual and seasonal indices of relative abundance . tow was increased from 50 to 75 to 100 m as fish for various life stages of winter flounder, from newly abundance decreased throughout the summer, hatched larvae to adult spawners, as well as egg pro-Winter Flounder Studies 13 1
t l i f duction, were computed using the data colixted in the for the 1976-82 surveys because most spawning had field sampling programs described above. These teen completed. Effort was standardized within each ; indices were based on various sampling statistics, year by replicating the median CPUE estimate in a which depended upon life-stage, sampling effort, and given week as needed so that effort (numler of tows) suitability of the data; a detailed description of each was the same for each week sampled. A 9$% con- , follows. fidence interval was calculated for each annual median , CPUE using a distribution-free method based on order statistics (Snedecor and Cochran 1%7). Relative anmaalabundance of adults A second index of abundance based on the size and sex distribution of the fish from catches standardized l The relative annual abundance of winter flounder by variable weekly and yearly effort was used in the ; spawning in the Niantic River has been described by annual recruitment and egg production calculations. trawl catch.per unit-effort (CP,UE). An annual CPUE Catches were adjusted by effort to insure that each : was calculated using the median trawl catch following size and sex group of fish was given equal weight [ data standardization. Tow distance (with exceptions within each survey week, among weeks in each sur- ; noted below) was fixed in 1983 because using the vey year, and to adjust for varying effort among years, same tow length at all stations was expected to reduce Detailed methods of calculating this index were given ! variability in CPUE, Previously, tows of variable in NUSCO (1989). To avoid confusion with the length had been taken at all stations. A distance of CPUE index, this measure is referred to as " annual , 0.55 km was selected as the standard because it standardized catch" throughout the remainder of this represented the maximum length of a tow that was report, possible at station 1. Since 1987, tows one-half or . two thirds of this length were frequently taken in the upper river to avoid overloading the trawl with macro-algae and detritus. Because catch data from station 2' Absolute abundance estimates , l were used also in the trawl monitoring program, hauls there were 0.69 km, standard for that sampling Absolute abundance estimatcs of winter Dounder program. spawning in the Niantic River were made using . 3 mark-and-recapture methodology and the Jolly (1965) , Duration of tows varied and was usually longer in model. Since 1984, brands from previous years of-the lower than in the upper river because of differen- sampling have been incidentally recorded, thus enabl-
- ces in tidal currents, wind, and amounts of extraneous ing the estimation of annual population size (N) for material collected in the trawl. A number of tows the entire spawning population in the river, in addi-from 1976-82, when distance varied, had shorter or tion the survival parameter (@) of the Jolly model-longer duration compared to the distribution of low serves as an estimate of annual survival, assuming tirnes in more recent years after tow distance was that between years few individuals strayed to other fixed. To lessen error in the calculation of CPUE, estuaries during the spawning season. Estimates of 4 data from exceptionally long or bricf tows were absolute abundance were obtained using the computer excluded from analyses. Catches of winter flounder program ' JOLLY' (M.J. Hines, U.S. Fish and Wild.
larger than 15 cm in tows made throughout the spawn- life Service, Patuxent Wildlife Research Center, ing surveys were standardized to either 15 min tows at Laurel, MD, pers, comm.). One correction was made stations I and 2 or 12 min tows at all other stations. in data analysis, which altered the results reported in The minimum length of 15 cm used for CPUE cal- NUSCO (1989). Both the numbers of fish marked culation was smaller than the 20 cm used for mark and recaptured used with the Jolly model were over-and recapture estimates described below because of stated in NUSCO (1989). Fish recaptured more than data limitations for the 1977 82 surveys. The method once within a year were mistakenly counted each time of calculating CPUE was modified last year (NUSCO they appeared, which is improper for the model. Cor-1989). Data used in the calculation of a median rected totals for fish marked and recaptured, as well as weekly CPUE did not include catches from the first the resulting recalculated absolute abundance esti. week of sampling in February for several years when mates, appear in this report. fish were scarce not from weeks in late April and May 14 Monitoring Studies,1989
{ Spawning stock site and cgg production stage 5. Transformation to juvenile was complete j and intense pigmentation was present near the caudal ; fin base. ; The percentages of mature females at various 0.5-cm length increments were determined from qual- , itative observations made of reproductive condition A geometric mean of weekly densities was used in [ from 1981 through the present. Percent maturity for analyses because the data generally followed a lognor- t mal distribution and weekly sampling frequencies var. i each size class was adjusted to give a smooth pro-gression by lengths up to 34 cm; larger fish were con- ied among some stations. Larval data analyses were sidered to be rnature. The fecundity (annual egg pro- based on densities standardized per 500 m3 of water duction per female) was estimated for each size class sampled. Data from day samples after March were using the following relationship determined for excluded Imm abundance calculations, except for estii i I Niantic River viinter flounder (NUSCO 1987): mating larval entrainment at MNPS, as older larvae apparently remained near the bottom during the day i fecundity = 0.0824 (length in cm)co6 (1) and were not susceptible to the bongo sampler. Sup-port for the exclusion of data collected during daylight - : Tids relationship was used with the annual standard- hours after March is provided in this report and is 'I id catch of mature females and their length compos- based on differences in densities from paired day and ition to calculate egg production. Annual mean fecun- night samples collected at the three river stations in ! dity was determined by dividing the sum of all indiv. April from 1984 through 1989 (98 pairs), Differen- ! idual egg production estimates by the standardized ces were compared using the Wilcoxon signed rank l catch of females spawning per year. Absolute esti- test (Sokal and Rohlf 1969). I mates of spawning females and corresponding annual egg production estimates for 1977 through 1989 were Examination of the temporal distribution of larval ! determined by scaling up the relative values by a fac- abundance indicated that it is usually skewed, with a tor of 30.8M (see Absolute abundance estimates in rapid increase to a maximum density followed by a Results and Discussion). Annual estimates of the slower decline, The cumulative density over time numler of female spawners were used later to derive from this distribution results in a sigmoid shape, the stock-recruitment relationship. where the time of peak abundance is the time at which the inflection point of the sigmoid occurs. Abundance, growth, and inortality oflarrac no Gompertz function (Draper and Smith 1981) was used to describe the cumulative distribution of the .
' in the laboratory, larvac were identified and counted abundance data because the inflection point of this-
- using a dissecting microscope after samples were split function is not constrained to be the central point of to at least one half volume. Only one of the repli- the sigmoid curve. The form of the Gompertz func.
cates from each bongo tow and entrainment collection tion used was: was processed for estimating larval abundance Up to 50 randomly selected winter flounder larvae were mea. C, = a(exp[ exp[.xt)]) (2) sured to the nearest 0.1 mm in standard length (snout tip to notochord tip). The developmental stage of where C, = cumulative density at time t ; each measured larva was recorded using the following a = total or asymptotic cumulative density r identification criteria: = location parameter. x = shape parameter
- Stage 1. The yolk sac was present or the eyes were t = time in days after February 15 not pigmented (yolk sac larvae).
Stage 2. The eyes were pigmented, no yolk sac The origin of the time scale was set to the 15th of ! was present, no fin ray development, and no flexion February, which was when winter flounder larvac gen-of the notochord. erally first appeared in the Niantic River. Least-Stage 3. Fin rays were present and flexion of the squares estimates and asymptotic 95% confidence in- t notochord has started, but the left eye had not migrat-tervals for these parameters were obtained by fitting ed to the mid line. the above equation to the cumulative abundance data Stage 4, The left eye had reached the mid line, but using nonlinear regression methods (SAS Institute . juvenile characteristics were not present. - Winter Flounder Studies ' 15
i 1 Inc.1985). De cumulative data were obtained as the dardized by tow distance, resulting in a density per i' running sums of the weekly geometric means of the 100 m2 of bottom. A moving average of three week-abundance data. The a parameter of the cumulative ly density estimates was used to smooth the trends in , curve was used as an index to compare annual abun- abundance for comparisons among years, dances. . Nearly all yotmg winter flounder collected were rnea- l A " density" function was constructed by deter- sured in the field or laboratory to the nearest 0.5 mm tuining the first derivative of the Gompertz function in total length (TL). During the first few weeks of ! with respect to time and directly describes the larval study, standard length (SL) was also ruasured because ; i abundance over time (abundance curve). His density many of the specimens had damaged caudal fin rays' function has the form: and to,al length could not te taken. A relationship i between the two lengths determir ed by a functional d, = (ups) / (explS exp( wt) + wt]) (3) regression was used to convert SL to TL whenever , necessary: where d, is the density at time I and all the other par-ameters are as descrited in Equation 2, except for a, TL in mm = 0.2 + 1.212(SL in mm) (6) which was rescaled by a factor of 7 because tie cumu. Growth of age-O winter flounder at each station was lative densities were based on weekly geometric examined by following weekly mean lengths through- > means and, thus, accounted for a 7 day period. Time out the sampling season. Mean lengths of young of peak abundance was estimated as the date tj, cor,
- taken at the Niantic River stations LR and WA from responding to the inflection point of the cumulative late July through September for 1984 89 were com.
Gompertz curve (Eq. 2) given by: l _ pared using an analysis of variance; significant dif-ferences am ng means were detennined with Duncan's tg = (log. IDl)/w (4) multiple-range test (S AS Institute Inc.1985). , The annual rate of density dependent mortality was To calculate a mortality rate for young, all estimated by relating annual larval abundance in the individuals were assumed to comprise a single cohort. 7 mm and larger size classes from station EN to the A catch curve was constructed with the natural annual total egg production index for the Niantic logarithm of density plotted against time in weeks. , River using the following relationship (Ricker 1975): The slope of the descending portion of the curve - providcu an estimate of the weekly rate of log,(lJE) = a + bE (5) instantaneous mortality (Z), Once Z was determined, weekly survival rate (S) was estimated as exp( Z) and ( where L = annual larval abundance of larvac 7 mm the monthly rate as exp([ Z][30.4/7]). and larger at EN as estimated by n (see Eq.2) Abundance ofjuveniles infall and winter ' E = annual egg production estimate a = intercept in fall and early winter, age-O winter flounder grad-b = rate of density dependent mortality ually dispersed from areas near the shoreline to deeper - ! waters. The catch of these fish at the trawl monitor. Density-dependent mortality is assumed to occur ing program stations (see the Fish Ecology section - when the slope (b)is significantly different from zero. clsewhere in this report for methods) during this time if b is positive, the mortality is depensatory and, if period was also used as an index of relative abun-negative, it is compensatory. dance. Data from inshore stations (NR and JC) tegin- , ning in November, nearshore Niantic Bay stations (IN Abundance, growth, and inortality of and ND) in December, and offshore stations (TT and juveniles in stunmcr BR) in January and continuing through February for t each grouping were used to calculate year class abun. , For data analysis and calculation of CPUE for age 0 dance. The 6 mean CPUE (NUSCO 1988b) was [ j winter flounder, the catches in all four tows of the selected as the index of abundance tecause it is the l 1-m beam trawl at each sta* ion were summed and stan- best estimator of the population mean when the data l-16 Monitoring Studies,1989 4
come from a distribution that contains numerous zero This allowed the determination of the number of values and is approximately lognormal (Hennemuth females from the same year class present at ages 3,4, et al.1980; Pennington 1983,1986). 5, and 6+ during successive spawning seasons. The age-6+ group was furthet subdivided into the numbers ne annual median CPUE of juveniles smaller than of fish expected to survive to age l$ by assuming an 15 cm (mostly age 1 fish) taken during t'w winter annual instantaneous mortality rate (Z) of 0.85 flounder spawning surveys was determined as des- through the terminal age. The final number of criled previously for adults. Median values were cal- females was then reduced to mature females (i.e., culated for stations in the lower Niantic River naviga- spawners) using the length specific proportions of tional channel (1 and 2) as well as for all river sta- mature fish estimated from annual catches in the tions combined when sufficient data were available. Niantic River for fish age-3 to $; all females age-6 For comparative purposes, an annual 6 mean abun- and older were assumed to le mature. Based on the dance index for these juvenile fish was also deter- observed abundance by age, it was found that a large mined using catch data from the five trawl monitoring fraction of age 3 females, considerable numbers of age-program stations outside of the Niantic River during 4 fish, and some age $ females were immature with the period of January through April. many not even present in the Niantic River during the spawmng season (NUSCO 1989). The final adjust. Stock and recndtment relationship (SRR) ments for mature fish provided an index of the fully recruited year class expressed as the aggregated num. A stock recruitment relationship (SRR) was used in ber of female spawners passing through each age-NUSCO (1989) to assess the long term effect of lar- class. An implied assumption was that catches in the val losses caused by entrainment through the MNPS Niantic River were representative of the population, cooling water system. An updated version of the except for all the immature fish that did not enter the same relationship is indirectly used in the present river until fully recruited. Although this recruitment report for the same purpose through the application of index could be used together with the annual number a stochastic population dynamics model. %e stock- of female spawners to derive an SRR, this would ig-and recruitment data were derived from the catch of nore size composition differences that affected annual winter flounder partitioned into age classes, because egg production. Therefore, the above index was ad-the spawning stock is made up of many year classes justed for differences in fecundity among fish using and the true recruitment consists of the reproductive the length fecundity relationship for Niantic River contribution expected over the life of each individual winter flounder given above (Eq.1) Finally, annual (Garrod and Jones 1974; Cushing and florwood egg production was summed up over the lifetime of 1977). Therefore, annual parental stock and the resul- each year class to determine the recruitment index as ting year-class of recruits were based on observed egg eggs and, then, converted to
- equivalent" female production and calculated life time egg production, spawners at the rate of one female spawner for each respectively, to account for variations in year class 561,000 eggs, strength and in fecundity by size and age. The assumptions and methods used to age Niantic River SRR and biological reference points.-
winter flounder and to calculate a recruitment index ex- Stock recruitment theory and the interpretations of pressed as equivalent numbers of female spawners biological reference points derived from SRR models were reported in NUSCO (1989). A brief account of were discussed in detail in NUSCO (1989). De SRR these methods is given below, along with some SRR. described by Ricker (1954,1975) appeared best suited ' based biological reference points that are useful for for winter flounder because the relationship between stock assessments, recruitment and spawning stock indices suggested sub - stantial decline in recruitment when the stock was Stock and recruitment Indices. Methods larger than average (NUSCO 1989). Moreover, used to calculate the annual standardized catch index Ricker's SRR has been applied to many different and total egg production of the parental stock were speeles (Cushing and Harris 1973) because it l given previously. De recruitment index was deter- simplifies the calculation of various biological ~ mined by applying an age length key descriled in de- reference points needed for stock assessment work. tall in NUSCO (1989) to the annual standardized Ricker's form of the SRR describes a dome-shaped catches of females partitioned by length frequency. curve where recruitment declines exponentially with Winter Flounder Studies 17
f l i inucase of either biomass or number of spawners u = (F / Z)(1. e-Z) (9) j above a certain optimal level of recruitment. The , mathematical form of this SRR is: where Z e M + F,and M is the instantaneous rate of ~ ! natural mortality. R, = nPi exp( SP,) (7) ! Only three of the biological reference points describ- i where R, is the recruitment index fer die progeny of ed in detail in NUSCO (1989) we used in this report. ; the spawning stock P, in year r and n and S are par. Dwy include: l ameters estimated from the dataf While a describes ili or lunMvh de m& I the reproductive potential of the stock (log, O is r equivalent to the intrinsic rate of increase), the par. P,,p = (log,[n]) / S (10) ameter is the exponential rate at which recruitment declines at large stock sires due to some form of den-equilibrium or sustainable stock for a given fishing sity dependent mortality. Recruitment of winter - flotmder was correlated with the exponential of mean i water temperature during February at the intakes of 'l MNPS, which is when most spawning and early lar. " O 8'I"l ' ' III) ' ' val development occurs (NUSCO 1988a,1989). Therefore, the panuncters a and were first estimated and fishing rate for " recruitment overfishing": , by fitting Equation 7 to the data and then re-estimated ! under the assumption that there was a signincant Fao = k>g,(0.9a) -(12) , temperature effect. This was accomplished by adding - i a temperature-effect component to Equation 7. This Deterministic stock assessment. Ricker's temperature-dependent SRR had the form: SRR described above and Equation 11 were directly-used in NUSCO (1989) to assess the status of the , R, = nP,exp(. P i)cxp($Treb) (8) Niantic River winter flounder stock. A new and more - reliable method based on an age structured model of where the second exponential describes the effect of the winter flounder population was developed for February water temperature on recruitment and the assessment work in the present report. Because stock. new parameter $ represents the strength of that effect, recruitment theory (Ricker 1954) was developed for > This effect was defined in the present report as the semelparous fish (i.e., those which spawn only once dcviation(T R b)of annualmean February temperature in their lifetime), Equation 11 may provide unreliable i from a kmg term (1977 85) mean February water tem. estimates of equilibrium stock sizes for iteroparous ,
- perature. When the February mean water temperature fish (multi aged spawning stocks), such as the winter q t was equal to the long-term average, the deviation 11 under. Although the parameter a in Equation 11 '
I (Tr.h) in Equation 8 was zero and the exponential could be adjusted for the effect of repeat spawning, - term equaled one. Thus, Equation 8 reduced to its c@au n a ammes ht no Mng mwtahty
## # "****"'"""* "" " #""" I initial form (Eq. 7) under average temperature con.
met in N case d wkter nounder Wame many . ditions. Nonlinear regression mediods (S AS Institute Inc.1985) were used for estimating the parameters in
# "E ' "" " " *" " '" 8 "I ,
gear. Simpson (1989) reported that about 72% of < l the above equations. LIS winter flounder landed by the commercial fishery wer between 28 and 32 cm; many of these fish The annual instantaneous rate of fishing (F), also
* #" "E# #"""" ""I * ""
referred to as fishing mortality or fishing rate,is an f r w nter il under by various markats and 1 important parameter affecting the reproductive poten-
.e u e n a e may w hm 6 -
tial of the stock and, thus, relevant for assessing other to 68% (Mayo et al.1981; llowell and Langan 1987), : impacts. In the case of the winter flounder, both fish-l with potential for significant discard mortality for age- ! ing and natural mortality take place concurrently i 2 fish associated with fishing operations. The modeb throughout the year and F is related to the actual frac. ing approach described later circumvents all these lion of the stock removed by the fishcry or exploita-tion rate (u) by the relationship: problems because it explicitly incorporates repeat 3 18 Monitoring Studies,1989
e e spawners through age l$ and fishing mortality from Effect of entralnment on the year class.
- age 2. This approach was used to estimate the winter The relationship of entrainment to year-class strength ,
Counder equilibrium stock sites at various fishing was investigated through nonparametric correlation : rates, analysis (Spearman's rank order correlation). Several relationships were examined by pairing annual The risk of stock collapse was examined in t;-ns entrainment estimates with each available index of of the limiting fishing rate (given by the estima'}d a - abundance for post entrainment life stages. The appar-parameter) and also by calculating the F value that ent survival rate of the young, from 7 mm and larger : would cause recruitment overfishing" as defined by larvae to age 1, was also examined for negative cor-Sissenwine and Shepherd (1987). They argued that relation with annual entrainment estimates. the stock is very likely to collapse before the fishing rate reaches its limiting value of log,(n) and proposed Reductions of stock sire. Entrainmentlos- l a new critical Fno that corresponds to the point at ses may be equivalent to fishing mortality when most which the slope R/P (l.c., the recruitment rate) le. of the compensatory mortality occurs during pre-comes 10% less than the slope at the origin of the entrainment life-stages (McFadden 1977). Flowever, SRR curve. This reference point (Eq.12) was also this does not imply that the removal of a given frac- - used by Gibson (1987) in his assessment of the tion of a larval year class is equivalent to removing a > Rhode Island winter flounder, similar fraction from the stock in each of 10 or more consecutive years by the winter flounder fishery, in , MNPS impact assessment addition, entrainment losses do not occur without eventually triggering compensation, even if density-lavalentrainment dependent processes operate largely prior to entrain- } ment. Year class losses are always compensated, ' The estimated number of larvac entrained at the with a lag, because they result in fewer spawners, MNPS cooling water intakes each year is the most which, in turn, will produce fewer larvac. This direct measure of impact on the local winter flounder lagged compensatory process is the manner by which stock, llowever, these estimates by themselves serve stocks compensate for fishing mortality that generally only as a relative year to year index of entrainment. occurs after density dependent processes cease to The true impact of this source of larval mortality to opemte, the winter flounder stock is difficult to reliably quan-tify, Until additional work contracted by NUSCO on Because the recruitment index calculated for winter
' the larval dispersal and entrainment model is com, Dounder was an aggregate of the spawners that sur-picted by MIT in 1990, direct estimates of entrain. vived year after year from a;;cs 3 through 15, the data ment together with the indices of abundance of already incorporated the cumulative effect of whatever various life-stages and the population dynamics model fishing mortality occurred each year. A similar argu-can still be used for assessment work by assuming a ment can be made for entrainment mortality that has ;
hypothetical range for the unknown fraction of occurred long enough for its effect to already be year class reduction due to entrainment. present in the recruitment data. This should be the case for MNPS Unit 1 entrainment (in operation Entralnment estimales Annual winter noun. since 1970) and for most of Unit 2 effects (in opera- l der larval entrainment at MNpS (station EN) was esti, tion since 1975), give that the recruitment indices mated as the median density (number per 500 m3) were calculated for the 1977 85 year classes. Tims, during the larval season times the total number of for the Niantic River winter 00under stock, further 500 m) units of seawater withdrawn by MNPS during reductions in the initial strength of year classes since the same period. A nonparametric method (Snedecor 1986 due to Unit 3 entrainment would be equivalent and Cochran 1967) was used to construct a 95% con. to similar reductions caused later by additional fishing . fidence interval for each median and corresponding mortality operating only once on each year class. On entrainment estimate. In addition, the density esti, the basis of this equivalence, the expected stock sites mates were also used as an index of larval abundance corresponding to current exploitation rates plus mor-in Niantic Bay. tality from Unit 3 entrainment could be calculated from Equation i1 modified as follows: Winter Flounder Studies 19 J
1 Pc(F,f) = (log,(ac II4fl)) / (13) Although the above equations provide a simple , framework for assessing the impact of MNPS using a where Pt(F,f) is the equilibrium stock corresponding detenninistic approach, an estimate of ENT for Unit 3 ! to a fishing rate (F) plus an entrainment equivalent operation is not yet available and, thus, only assumeo values can be used in a s,mulation i of best and ; rate (f), and the parameters a and are from the , , SRRs (Eqs. 7 and 8). The values of I can be worst case scenarios. A note of caution is that the r so-called
- equilibrium stock size" is the expected size calculated with the following equation: ,
to which the stock would slowly converge if both ' fishing and natural mortalities remained constant.long f . log,(1.ENT) (14) ;
=
enough (a few times the lifetime of the fish; Shepherd where ENT is the conditional mortality rate or frac- k "" I""" " " " " "" **I I" practice, real stocks fluctuate about the equilibrium tion by which entralnment reduces the strength of the size instead of converging to it. Furthermore, chan- ' Y#I"*** ges for a multi age stock like the winter flounder will cly in tem oMong4un (1420 yms) avemgr The above equations, introduced in NUSCO (1989), s zes rather than on a year to-year basis, in addition, are equivalent to the so-called equilibrium reduction equations (EREs) derived by Savidge et al. (1988). In ennt mnental vadaMiy wiH alwazs result in uncer-tainties that would make any determimstic assessment fact, the model EREl (Eq. 3) of Savidge et al. (1988) rehah h au sese reasons, k nnal aum-is algebraically identical to the above Equations 13 ment in tMs nput was based on the use of a stochas- ' and 14 combined, with F corresponding to the tic population dynarm,es model and probabilisuc risk prevalent exploitation rate during the years represented auessment (PRA) methodology. by the time-series of data used to estimate a and , In that case, Equations 13 and 14 become:
' Winterflounder stochastic population Pg(ENT) = loge (n[1 ENT))/ 4 # " d#I (15)
Itackground and model'in g strategy, which is model ERE1 of Savidge et al. (1988), They Models represent a compromisc between realism and further proposed to describe the percentage change in complexity. A realistic model of fish population , the equilibrium stock as the percentage reduction in dynamics should incorporate a mechanistic description - the impacted stock relative to the non-impacted stock of the complex life cycle of the fish with all the (P,p) given by: biological and physical processes involved. This is never possible because in addition to the imprac. IC = 100(Pg Pup)/ Pnp (16) ticality of such complexity, many of the processes < that need to be modeled are known very imprecisely This expression becomes the following equation and detailed data for parameter estimation are generally l (Savidge et al,1988: Eq. 5) when PE and P,pabove lacking. Therefore, a truly realistic model would re-l are replaced by Equations 15 and 10, respectively: quire so many assumptions about specific parameter , values and functional relationships as to render the PC = loge (1 ENT)/ loge (n) (17) model overly unreliable for prediction purposes. , More general models, such as those based on stock-l Furthermore, Savidge et al. (1988) demonstrated by recruitment theory, require estimates of only a few means of simulation and a sensitivity analysis that parameters which are assumed to represent reasonable' Equation 17 was equally reliable for both semelparous
- averages" of the more complex processes they sum-l' and iteroparous stocks under the assumption of steady marize. Although not always reliable, the data needed 3
( state or equilibrium stock. "Ihis result is not surpris- to estimate the most critical parameters in a stock- ' ing because the conditional mortality corresponding recruitment based model are generally available for-- l to larval entrainment impacts cach year class only fish species that are commercially important. Among once, regardless of the particular age structure of the such species, the winter flounder has been extensively. spawning stock. studied and estimates of stock-recruitment parameters - for various New England stocks have been derived ,- (Gitson 1989c). 20 Monitoring Studies,1989 r e
t The population dynamics model developed for the (mostly additions and multiplications) iteratively over Niantic River wintet flounder stock was tw.ed on the the age index (1 through 15) and over the number of Ricker form of SRR described in NUSCO (1989). years specified for each simulation. This approach Although the specific SRR equation fitted to the data was algebraically identical to the Leslic matrix for. (Eq. 8) does not appear explicitly in the model for- mulation and simplified the computer code when mutation, the mechanisms underlying the Ricker describing the fish population either as biomass form of recruitment are incorporated in a set of equa- (allowing for size composition within each age class) tions that the model uses to calculate mortality or numbers of fish. A similar implementation of through the first year of life. Beyond that point in adult population dynamics simulation was recently the life cycle simulation (i.e., age 1), the population used by Crecco and Savoy (1987) in their model of model simply describes the annual reduction of each the Connecticut River American shad (Alosa sapidis-year class through natural mortality and fishing sima). together with aging and reproduction. The latter occurs at the beginning of each model time step of Model components. The simplified flow chart length equal to I year. These processes corresponding shown in Figurc 5 describes the computer program to the dynamics of the adult population have been for the NUSCO impact assessment model under implemented in many previous fish population development. Components depicted by boxes with models by means of Leslic matrix equations (e.g., dashed lines denote parts of the model that were liess et al.1975; Vaughan 1981: Spaulding et al. notused in the present application and will not be dis-1983; Reed et al.1984; Goodyear and Christensen cussed here. These components, however, will be 1984), in the present winter flounder population used in the near future when the MIT larval dispersal model, adult fish dynamics were implemented ex- and entrainment model and the results of mitochon-plicitly by grouping fish into distinct age-classes and drial DNA (mtDNA) larval stock identification studies by carrying out the simple computations needed hput cata and . . . . . . . . . . . . . . . . . . , simulahon parameters l el water
,m ab-l
...... e entrainmeni i l
'**P"'"
. 'M"*.a
*a l
fch ng ohntlul n l g Mk
,........... to,vai 6spe,asi .
l l e e
..yl............l.
and Lanral cohorts
. . . . . . . . . . . . yl and entrainment l l r .
l s 4 Compensaten. Enea.nmeni and ,q'...............................a e Ace 1 cohort Y A< cohort calculations Annued adult Probatnhste and > populabon y nak l Natural and fishin0 mortahty estimates assessment Y Y Y l 6 pawning stock size OUTPUT eM E og producson estrnates Fig. 5. Diagram of computer simulation model for assessing the long term effect of larval winter flounder entrainment at MNpS. Model components with dashed boxes and arrows have not been used in the present application. Winter Flounder Studies 21
I ongoing at The American University become avail. should te mentioned here that the scaling factor ASF able, he other components depicted by boxes made is simply a multiplier that converts age 3 female of solid lines constitute the stochasdc winter flounder recruits into the potential recruitment of the year. population model presently in use. He functionality class. This recruitment is defined as the cumulative of some of these components should be clear from the r umber of mature females from the same year class figure and no further descriptions are provided here, that survive to spawn year after year during the llowever, critical components, such as the one labeled lifetime of the fish. The algebraic form of this mul-age-1 cohort, the two random input boxes, and the tiplict, also derived in the Appendix, is identical to component that performs the probabilistic risk assess- the numerator of Equation A 4 in Christensen and ments are described below. A list of the actual input Goodyear (1988). data used in the application of the model to the Nian-tic River stock will be given later in Results and Discussion. Random variability. Stochasticity in the win-ter flounder model (Fig. 5) has two annual com-ponents: a random term that represents uncertainties Calculation of fish surviving to agel. associated with the estimate of Ricker's a parametert
%c most critical aspect in the fonnulation of a stock- and annual environmental variability in the form of recruitment hased population model is the specific random deviations from the long term mean February equation and parameters used to calculate total mor- water temperature, which occurs during the period of tality during the first year (i.e., from egg through age- larval development. Dese two components of annual 1). The equation used for this purpose in the winter variability are incorporated into the calculation of flounder model was derived from Ricker's equilibrium each new year class via the mortality from egg to age-equation for Zo (total instantaneous mortality from 1. The term n, in Equation 18 is the random
- poise" egg through maturation age) and involved the exten- simulated as independent random variates from a sion of stock recruitment theory, which was normal distribution with zero mean and c2 variance, developed for fish that spawn only once, to The valuc of o is estimated during the model calibra-iteroparous fish with milli age spawning stocks, tion runs as the amount of variance required to The form of this equation as used in the present generate n values within the 95% confidence interval model was:
of the estimate of a used in the model. Similarly, l the tenn 4WT, in Equation 18 represents the effect of Zo,, e log,(FEC) + log.(ASF) log,(n) + n, - annual environmental variability on larval survival QWT,Z.2+hP, 8 (18) via February water temperatures. This effect tecomes iandom when the February water temperatures are where the subscript I denotes the time step or simula. themselves simulated as independent random variates tion year and implies that non subscripted terms from a normal distribution with mean and variance remain constant from year to year; n, , and $ are the equal to the mean and variance of February water three parameters in the SRM (Eq. 8) estimated from temperatures at the MNPS intakes during 1977 85. the stock and recruitment data; FEC is the constant mean fecundity of the stock expressed as the number of female eggs produced by each female spawner; Probabilistic risk assessment (PRA). The ASF is a scaling factor to adjust a for the effect of a stochastic simulation of fish population dynamics multi age spawning stock; n, and WT, are independent provides a convenient framework for probabilistic as-random variates from two specified normal distribu- sessment using PRA methodology. This type of as-tions described later; Z i 2 si the instantaneous mor- sessment is based on Monte Carlo methods tality through the immature age-classes; and the last (Rubinstein 1981), where many independent random term (DP,) is the feed-back mechanism simulating replicates of the stock dme series are generated so that stock dependent compensatory mortality, which varies the mean stock size and its standard error can be es-according to the size of the annual spuwning stock P8 - timated. Alternatively, the Monte Carlo replications can be used to derive either the sample distribution function (Stuart and Ord 1987) without assuming a Although the complete derivation of the above equa-known statistical distribution, or the probability den-tion is given in the Appendix to this report section,it 22 Monitoring Studies,1989
sity function (PDF) under the assumption of a log. Results and Discussion normally distributed stock size (Tuljapurkar and Or-zack 1980). Both methods can be used to calculate Adult winter flounder the probabilities of postulated outcomes, such as stock size reductions. PRA methodology was used to Relative annualabundance assess the risk of stock reduction resulting from three different levels of larval entrainment at MNPS Population surveys of adult winter flounder spawn. simulated in this report. In addition, the effect of ing in the Niantic River have taken place each year increasing fishing rates from 0.50 to 0.55,0.60, and since 1976 (Table 1). Catch data from these surveys 0.65 was investigated by calculating equilibrium were used to calculate two relative indices of abun-stock sizes in a deterministic application of the model dance: trawl CPUE and annual standardized catch, and the corresponding long term (40 years) estimates The latter index was used with length and reproductive - of mean stock site in a stochastic simulation. Information to compute female spawning stock size, which will te discussed below. These two indices were highly correlated (r2=0.98), which supported die - Model assumptions and limitations. The reliability of methods used in data standardizations, major model assumptions concern the underlying form of the SRR used and the reliability of the SRR TABLE 1. Annual Niantic River winter flounder' population paramCICr Cstimates. First, because the model incor. sur eys during the spawning season from 1976 through 1989. potated the Ricker fonn of SRR,it was assumed that stock-dependent compensation and the postulated ef- go,3,, ,, feet of water temperature on larval survival (Eqs. 8 Year Dates sampled weets sampled and 18) applied reasonably well to the Niantic River , , winter flounder stock. Secondly, it was assumed that 1976 March 1 April 13 7 { 2 6 the three parameters of the SRR were correctly esti, 3 mated and that u,in particular, was a reliable estim 1979 March 12 April D 6 ate. Thirdly, although the population was not as- 19so March 17 April 15 $ sumed to be at steady state, the average fecundity and 1981 March 2 - April 14 7 survival rates for fish age I and older were assumed to 1982 February 22 April 6 7 remain fairly stable over the period corresponding to jIl[* 7 the time series data used to estimate the SRR 1985 February 27 April 10 -7 parameters. Although the last assumption may gen. 1986 1chruary 24 April 8 7 crally apply to fecundity rates and adult natural mortal- 19s7 March 9 April 9 5
- j. ity, fishing mortality rates are less stable. Changes 1988 March l April $ - 6 ;
in exploitation rates from year to year should not 1989 Fehmary 2t April 5 7* j cause estimation problems as long as they are not sys-
,
- Minimum 17e for marking was 15 cm during 1976 s2 and tematic (i.e., change m the same direction year after 20 cm thercarier.
year). IleCause diese assumptions are seldom com- b timited sampling during second week due to ice formation. pletely met, applications of the model included calibration runs to validate predictions under both deterministic and stochastic modes by comparing The winter flounder adult population abundance sur-model results to recent series of stock abundance data. vey for 1989 began on February 21 following heavy q L in addition, every effort was made to ascertain the rains which cleared ice cover in the upper river. As in reliability of the a parameter estimates used in the previous years, macroalgae and detritus remained abun-model. Finally,it should be noted that the stochastic dant in the upper navigational channel (station 4; Fig. simulations assumed a random environmental vari- 2), which precluded sampling there after the first week ability about some mean water temperature value. In of study and hindered work in certain portions of the other words, no temperature trend or large scale envir- upper river basin (sta. 51) and northernmost section onmental changes (e.g., global warming) are assumed of the river arm (sta. 54). As in 1988, few winter to occur during the years simulated in a population flounder were found in the navigational channel (sta. l projection. I and 2) and fish were most common in the upper riser (sta. 5154). The 1989 survey was conducted Winter Flounder Studies 23
]
9 during some unusual periods of weather which Niantic River spawning stock as 5 and 6. year olds affected weekly sampling cffort and, most likely, (NUSCO 1999). Measurements of fish collected were - winter flounder distribution. Initially, most fish were distributed in a manner that indicated more larger and, - captured near the edges of the remaining ice in the presumably, older fish present after.198$ (Fig. 7). upper river., llowever, cold weather in late February The distributions for 1986 and 1988 (not shown on> allowed lec to reform and only the lower river naviga- the figure) generally fell between those of adjacent. tional channel was open during the first week of years. These fish were likely the remnants of the March. As few adult winter flounder were taken large winter flounder year classes produced during the' there, sampling was halted for a week.. Despite con ' It.le 1970s and early 1980s.; tinued cold weather, the ice disappeared again the fol-lowing week and trawling operations resumed;. Win-ter flounder were relatively scarce throughout the river g 70 crut (als on.) - at this time. Ily late March record warm air temper- go atures in southeastern Connecticut and heavy rains produced a strong stratification in the river with 50
/
warm,less saline water at the surface. Many of the 4o .y spent fish apparently had left the river by the end of / the monih. 5 30 / E 2 0-The adjusted median CPUE of winter flounder l 3,. larger than 15 cm was 12.2 for 1989, a decrease from !g the value of 16.8 recorded in 1988 and the second O' - - - - - - - - - smallest index of the 14 year series (Fig. 6; Table 2), nne 80 el e 64e5ese7 esse-The reduction in this index of adult stock size may-have reflected,in part, some of the difficulties in sam-Fig. 6. Annual median CPUE (12 standard errors) for . pling this year, as well as relatively poor year classes - , Niantic River winter flounder larger than 15 cm from-produced in the mid-1980s that were recruiting to the 1976 through 1989c spawning stock. Most females fully recruit to the ' TAht.l! 2. Annual 9.l m citer trawl adjusted median CPUti of winter Counder larger than 15 cm' taken throughout the Niantic River during - the 1976 through.1989 aduh population abundance surveys. - Tows Adjusted Coeffucient o Survey Weeks acceptable < number of hiedian - 95% confidence c of-year sampled for CPUli" tows used' CPUti interval -a skewnessd' 1976 7 143- 231 37.0- 34.2 39.6 3.0 t 1977 6 184 228' 23.1 -- 20 4 26.4 > - 1.95 ' 1978~ b. 137 159 21.0- 18.8 27.0: 1.83" 1979 5- 122 145 33.6- 25.549.5' l.527 1980 5- 112' 145 36.0 30.0 43.2 L 1.68; i 1981- 7' I82 231 51.6- 45.6 56.4- 3.50 1982- 5 118 150 42.6- 42.6 46.0 1!! 4 -- 1983 7 232 238 30.2 26.2 31.8' O.85-1984 7 245 287 16.8 15.8 18.0' l.17' 1985 7 267 280 14.8 14.2 15.4 1.33 . 1986 7 310 336 10.2- 9.7 11.1 1,47 ~ 1987 5 233- 270 14.B " 14,1 16.2 - 1.46- ') 1988 6- 293- 312 16.8 15.7 17.5: 0.50- , 1989 6- 277 318- 12.2- 11.1 13.34 1.08- ' 1
^
- hicady age.2 and older fish. -
b Only tows of standard time or distance were considered.
' liffort equalised among weeks. 5 d 7ero for symmetrically distributed data.'
24c Monitoring Studies,1989
l l i I 6' ' 6 5' f 8 4' '/ : E f 3' ' i
$ s\ ,
2' g I. ~ J / 3 .
.i 87 i
./ v 5 89 <
- s. 4 0- , -. I 20 25 30 35 40 45-LENGTH (cm) :;
Fig. 7. Length frequency distributions for winter flounder larger than 20 cm taken in the Niantic River during adult popula. I tion abundance surveys in 1985,1987, and 1989. ; t Absolute almndance estimates brands used during the earliest years of the surveys, f
- absolute abundance estimates were restricted to fish - ,
, Estimation of absolute fish abundance is frequently branded during 1983 88 and recaptured in 1984 89. j l accomplished using mark and recapture methods. The . .. . .
)
l Jolly (1965) stochastic model used with the Niantic During 1989,2,821 winter flounder larger than 20 - ; i River adult winter flounder mark and recapture data em were captured and branded, the second fewest after ' has been considered among the most useful in provid- 1987 (Table 3), A total of 232 fish marked during r o ing abundance estimates for open populations as long 1985 88 was recaptured, including 145 branded la , i as basic assumptions are approximately met (Cor. 1988. Recaptures made 1 year.after initial branding - mack 1968; Southwood 1978; Begon 1979). Abso-l ranged from 2.2 to 4.0% of the fish marked; These , l lute annual abundance estimates for Niantic River data were used with the Jolly (1%5) model to provide 1 L winter flounder larger than 20 cm were calculated by absolute abundance estimates (N); survival (4), ; L pooling together all fish marked and released during a recruitment (R), and sampling intensity (p) were also i particular year and observing recaptures in subsequent determined. Abundance estimates of adult winter ,
- years (NUSCO 1989). A minimum of 3 years of data flounder in the Niantic River during 1984 88 ranged ['
is required by the Jolly model to produce an estimate; from about 48 to 77 thousand (Table 4).. As previ. thus, fish branded this yearjoined the marked popula- ously noted, corrections were made this year to the ; tion of winter flounder and will enable the estimation mark and recapture data given in NUSCO (1989). As -; of population size for 1989 beginning in 1990. Be.' a result of the reductions in the numbers of fish both- a cause of uncertainty in data records and ambiguity in marked and recaptured, decreases of 9 to 11 thousand . 1) Wintet Flounder Studies 25 > t
, , , -a ~--- e
[ i TAlll2 3. Mark and vocapture dets f rtsnl983 through 1988 used for totimating abundance of winter fl<nmeer larger than 20 cm in the Nann. ! tic River during the apawning neascui. Tatal Total ma Niamher _ Receptwos j Svevey numhet previously mated and 'lotal (yant snarked): .
. year cheerved mathed seleased - recapewed 1983 1984 198$ 1986 1987. 1968 1983 5.615 5,615 5.615 .0 1984 4.103 3.973 4,083 130 130 t 1985 3.491 3,350 3,407 141 47 94 . .
1986 3.03) 2,887 3,010 144 23 45 76 i 1987 2.578 2,463 2,573 -l15 2 13 27 73 f 1988 4,333 4,106 4,309 227 7- 22 31 63 104 l 1989 2,821 2,589 2,754 232- 2 11 9 33 32 145 g
.t t
5 i
'L TAliti 4. listimated abundance of winter naimder larget than 20 cm taken during the spawning semitm in the Niantic Itivet from 1984 through 1988 na determined by the Jolly (1965) mark and recapture modsl. f
- =[
Abundance Statulard - Probability Standaed L estimate error d 95% Q of survival erme 95% Q i Year (N) N for N ($) . W$ for $ ' f 1983 0.340 0.04I. 0.208 0.422 [ 1954 59,790 8,808 42,457 77,054 0.528 0.064 0.402 0.654 j 1985 76,217 10,677 55,290 97,144 0.367 0.045 0.278 0.454 19k6 45,396 6,54l 36,11$-61,756 0.663 0.078 -0.509 0.817 76,910 10,752 $5,837 97,984 0.313 0,$98 1987 0.471 0.06$ j 1988 $3.133 7.30$ 38 817 67.433 Mean - 62,998 4,047 55,124 70,871 0.474 0.017 ' ' 0,440 0,507 ; v i
- i. Sampling Standard Annual Standard ~i intensity error af 95% Q recruitment . error . 95% Q ;
[ Year (p) p forp (B) da for 8 ; l ! 1984 0.068 0.0101 0.048 0.088 44,663 -8.812 27,391 61,934 [ 1985 0,046 0.0064 0.033 0.058 21.032 $,289 ' 10,66$ 31,398 1986 0.062 0.0083 0.045 0.078 44,485 8,978 - 26,888 62,082 . 1987 0.033 0.0047 0.024 0.042 -16,948 $,338 6,486 27,410 ~ ! _ 1988 0 081 0.0112 0.0$9 0.103, ! Mean . 0.058 0.0038 0.051 0.065 31,782 2,260 27.352 36,212 i
.I L fish were seen in estimated anmmt abundance for 1984- dices (Table 2) for 1984 88, Eachindex decreased by ,
86 compared to estimates reported in NUSCO (1989), about a third from 1985 to 1986 and both increased i llowever, another year of recaptures of previously again in 1987 to values nearly the same as in 1985. j branded fish also most likely provided more accurate if this correlation between absolute population estii. j
~
estimates for 1984 87 and allowed for the initial mates and CPUB is reliable, then based on this > abundance estimate for 1988, relationship, total numbers of winter flounder larger than 20 cm in the Niantic River may.have been as - The total population abundance estimates were large as 200,000 fish during their peak abundance in - 1981, 1 remarkably well correlated with the median CPUE ini I l
-26 Monitoring Studies,1989 ,
e
, -.-y. ,,
i Although 95% confioence intervals are given for 3.24% of the absolute values. This also assumed that the abundance estimates, because of Jolly's variance the 1977 83 ratios would have been similar, had abso-formulac the standard errors of N are correlated with lute abundance estimates been available. Thus, a N making them generally unreliable as a measure of multiplier of 30.864 (103/3.24) was used to scale sampling errot, escept at very high sampling inten- abundance indices into absolute numbers for sities (Manly 1971; Roif 1973). Sampling intensity assessments discussed telow. (p), or the probability that a fish will be captured, was estimated between 0.03 and 0.08 (Table 4). Such Spawning stock site and egg production low proportions may result in poor estimates of abundance (Bishop and Sheppard 1973) Sampling Winter flounder life history data, including length, intensities of alcut 0.10 are recommended to obtain sex ratio, and maturity observations, have been reliable and precise estimates of geputation size and recorded during cach adult abundance survey since survival rates with the Jolly model (liishop and 1977. The sex ratio of winter flounder larger than 20 Sheppard 1973; Nichols et al.1981). Lower sam- em during the spawning season in the Niantic River pling intensities may give acceptable estimates if over the past 13 years ranged from 0.78 to 2.03 population size (as for the Niantic River winter females for each male (Table $). he 1989 value of flounder) is telatively large and the numler oi marked 1,32 was nearly the same as the geometric mean animals is also relatively high (liic,,htower and Gilbert (1.34) of the series. More males than females were 1984). Any loss of marks because of tag loss and taken only in 1986 and 1987, Ratios of 1.50 to 2.33 mortality, however, would require increased sampling in favor of females were reported by Saila (1962a, intensities. Other sampling errors, model assump- 1%2b) and flowe and Coates (1975) for other popula-tions, and biases inherent in the Jolly model that tions in southern New England. most likely affected the winter flounder population estimates were discussed in detail in NUSCO (1989). TA11tI 5. Femate io male ses raitos of wmier nounder inten dur ng the spawning season in the Nianiic Ither from 1977 Annual estimates of survival (@) provided by the 'h'""8h I'8 Jolly model are almost always overestimated (Ilishop w .ored and Sheppard 1973). Loss of brands or failure to Year All fish capiured fish > 20 cm record them also lead to bias and loss of precision in estimates (Arnason and Mills 1981). Nevertheless, 1977 1.03 1.26 the mean of the somewhat variable annual survival estimates was 0.474 (Table 4), which compared g 2 1 2 j 1980 2.66 2.03 i favorably to an estimate of 0.453 made using 19st 1.42 t .61 indegendently collected age-fn:quency data from 1981 1982 1.16 1.50 83 with a catch curve (NUSCO 1987), and the value us3 1.52 1.52 8d of 0.4274 (corresponding to Z=0.85) chosen in this ['985 i' i' report as an average for the 1977 85 year classes- 1986 0.92 0.92 1987 0.78 0.78 The good correspondence between the median trawl loss 1.50 1.50 CPUE index and the Jolly estimate noted above led to n89 1.32 L32 further comparisons among abundance indices. %c o,,,,,,;, ,,,n t34 i,34 annual standardized catches of all fish larger than 20 cm for 1984 87 were compared to the total abundance estimates from the Jolly model. The 1988 value was The rate of winter Counder spawning in the Ninntic not used tecause it was based on recaptures from only River was noted by weekly changes in the percentage 1 year and was subject to greater bias than the other of gravid females larger than 26 cm, the size at w hich estimates. For the four Jolly estimates used, the an-about half of all observed females were mature (NUS-nual standardized catch indices made up 2.8 to 4.5% CO 1988a). Generally, most spawning was com-of each annual total population, and had a geometric pleted by late March or early April as relatively few mean of 3.24%. Because of this consistency, the gravid females were found afterwards in the river (Fig, relative numbers of females and eggs produced each 8). In most of the years, ice in the river would have year were auumed to represent, conservatively, about Winter Flounder Studies 27 ___o
l l r 60' 4 50' 40* 1986 1985 \ ; 3g. 19B7 39gg 20' N' N 19 8 8 .. * ** ***"' go.
- o. .
FEBRUARY MARCH APRIL , i Fig. 8. Weekly percentage of Ninntic River female winter flounder larger than 26 cm that were gravid during the 19tl$ through 19H4 adult population abundance surveys, prevented starting population surveys in January or year basis (NUSCO 1989). Data from more recent , early February, so appmximately two-thirds of the years (1983 89) most likely were less affected by females examined during late February and early these adjustments as nearly all fish were measured and , March had spawned before sampling began, classified as female or male and weekly effort was' { Apparently the majority of females spawned earlier irlatively uniformt larger proportions of fish during during the winters of 1988 and 1989, as few gravid 1977 82 were not classified by sex and only smaller ; fish wcre seen throughout these surveys. Spawning subsamples of fish were measured. Using available appeared to have been correlated with water data on sex ratios, sexual maturity, and fish length. >
- temperature and in relatively cold years (e.g.,1977 firquencies, the fraction of annual catches determined - !
and 1978) proportionately fewer females spawned to be adult females was used as an index of spawning : during the earlier portion of the surve), whereas in stock size. The proportion of females considered to . ; warmer years (e.g.,1983 and 1987) more were spent be mature for each 0.5 cm length increment was used ; at the beginning of sampling.(NUSCO 1987). with the 1977 89 standardized catches of females to l obtain relative annual indices of female spawners. j Determination of the size of the Niantic River win- Mature females comprised approximately one third to . ! ter flounder female spawning stock is desirable for one half of each yearly total, with relative numbers of ! various stock assessments. In 1988, annual catches female spawners ranging from 655 in 1986 to 2,752 of fish larger than 20 cm (predominantly adults) were in 1982 (Table 6). These annual values differe41 first adjusted in order to standardize them by length somewhat from the median CPUE of all winter - and sex on a tow by tow, week by weck, and year by flounder larger than 15 cm, presented earlier. [ 28 Monitoring Studies,1989
TAllLE 6. Relative and abacdute annual statulardized utch of female spawners and egg prtuluttion for Niantic River winter flounder Inwn 1977 through 1989. i Relative inden Relative inden Survey of spawning % mature Average of tcent Total female Total egg yest females' females 6 fecundity
- egg pn=luction 8 stock sin' production (X10')*
1977 884 36 446.336 394.6 27,287 12.179 1978 1412 $1 $08,096 717.5 43,$87 22.147 1979 1820 37 478,108 $35.3 34,5$6 16.$21 , 1980 903 34 469,976 424.3 27,861 13.093 i 1981 2669 44 $ 18,27$ 1383.1 82,366 42.688 i 1982 2752 49 $ 80,227 1$96.8 84,938 49.284 r 1983 1669 46 $78,845 1082.0 $7,691 33.394 > 1984 871 40 $75,822 $01.6 26,883 15.480 ' 1985 1042 43 609,229 639.5 33,410 20.354 19k6 655 42 667,065 436.7 20,20$ . 13.478 g 1987 832 39 624,085 $31.6 26,292' 16.409 1988 1279 $3 677,910 866.9 39,471 26.758 1989 9s4 $2 728,042 716.2 30,364 22.106
- llaned on pniportion of the relative annual standardiud catches of winter flounder that were mature females, i 6 As a pnipnion of all winter floumlet 20 cm or larger.
- Total egg pnxtuction divided by the numhet of spawning females.
- A relauve indes for yeatio. year comparisons and not an absolute estimate of productkm.
' Calculated on the assumption that the relative annual standardaed catches were approsimately 3.24% of absolute values. ,
llowever, this was not unexpected because of annual- t ion (range of about 12 to 49 billion) was greatest in + ly varying sex ratios and differences in percent the carly 1980s. Values have increased in recent years maturity due to changes in length frequency as older and larger females dominated the reproductive distributions. Average fecundity was smallest during stock. The total number of female spawners was used the late 1970s, when smaller fish were more abun- as one of the bases for the SRR, which will be dis-dant, but in recent years it has been greater because cussed later in this report. ' the spawning stock had greater proportions of older and larger fish. The 1989 value of 728,(M2 eggs per Larval winter flounder female was particularly large, The relative index of total egg production reflected female stock abundance ' Abundance anddistribution and length distribution and was greatest from 1981 ! through 1983 because of peak population abundance Larval abundance estimates can be biased due to ; and moderate average fecundity, Despite having larval behavior, an example of which was the prev- t relatively similar female abundance indices in 1980 iously identified difference in densities of larval winter 6 (903) and 1989 (984), cgg production during the latter flounder collected during day and night (NUSCO year was considerably higher (716.2) than the former 1987), No differences were apparent during early (424,3) because of the larger females which con- development (up to about 4 mm), but as larvac grew stituted the spawning stock. larger densities were found to be progressivcly greater - l in night collections compared to those taken during Absolute estimates of adult female stock and egg the day. For these reasons, sampling in the Niantic - - production were made assuming that relative annual River since 1984 has been conducted during daylight , standardized catches were approximately 3.24% of ab- during the occurrence of early developmental stages ; ( solute values. Multiplying relative female numbers and at night when later developmental stages # l and egg production by 30.8M enabled estimation of predominated. Because it was not clear when den-absolute spawning stock size and egg production sities in night collections began to exceed those from (Table 6). Female spawners, ranging in number from the day, sampling during both day and night has been - about 20 to 85 thousand, and total annual egg produc- conducted over a transitional period during the first 3 Winter Flounder Studies 29 i i
._- =
weeks of April since 1984. A comparison of 98 relationship was found betwoon the annual abundance [' paired day and night samples collected in the river in the river and boy. This suggested varying annual during April of 1984 through 1989 showed that den- larval mortality rates occurred when larvae were sities at night were significantly (p<0.001) greater flushed from the river into the bay, than those during the day. During the first 3 weeks i of April, developmental stage composition was about equally divided among Stage 1 (30% of total catch), so-Stage 2 (34%), and Stage 3 (35%). No significant NwnC RNER diel difference occurred for densities of Stage I tarvac, 40 but densities at night were significantly greater for $ toth Stage 2 (p<0.01) and Stage 3 (p<0.001) larvac. The inclusion of day samples, therefore, would have {30 l produced an underestimate of total abundance in April 20 and data from day collections for all stations during -
- April through the remainder of the larval season were to excluded from the analyses, except for the calculation of entrainment estimates at station EN. Because ,0,,,,,,,,,,,,,
previous reports included data from April day Mrt samples, their exclusion this year caused the results , of some analyses to differ slightly from those ' presented in NUSCO (1989). Ilowever, no con-clusion was ahered because of this change. y 1hc abundance of hirval winter flounder in 1989 for N MDC W the Niantic River (stations A, B, and C combined) was compared to that of Niantic Bay (stations EN and g8 l NB combined) using abundance curves estimated (Eq. 'E i 2) from the Gompertz function (Fig. 9). The pattem i found was similar to that of previous years (NUSCO 1' 1987,1988a,1989), in the river, larval abundance peaked during early March and then rapidly declined. This decline can be attributed to mortality and e. . . . . . . . flushing from the river. In the bay, the increase in em em m oen sam M e7JuN 27JUN abundance from mid March to mid. April coincided Mit with the decline in the river, suggesting that a maior Fig. 9. Abundance (no/500 mh curvu atimated from source of larvac in the bay was the Niantic River. In the Gompertz function for larval winter nounder at Ninn-1 1989, the maximum density in the tviy was much tic River and Bay in 1989. lower (about 300 per 500 m3) than in the river (about ! 4,000 per 500 m 3). 'lliis difference was expected due ' l to mortality during the period of flushing from the The annual spatial abundances of the first four river and dilution within and flushing from the bay. developmental stages were examined based on the Annual abundances in the river and bay were com. cumulative weekly geometric means; the abundance ' pared using the a parameter of the Gompertz function and distribution of Stage 5 larvae were not examined as an index of abundance (Table 7), This parameter is because so few were collected (Fig.10). The cumu- ' actually an estimate of the area under the abundance lative or sum of the weekly geometric means is an curves presented in Figure 9. For the river, larval approximation of the a parameter from the Gompertz , abundance in 1989 was lower than that in 1988, al. function used above to compare abundances. The a though it was the second highest for the 7 year parameter could not be used in this instance because period. Abundance in the bay during 1989, however, the Gompertz function could not be satisfactorily fit was about average. Assuming that many of the lar- to data from stations where the developmental stage vae in the bay originated from the river, no apparent was rarely collected (e.g., Stage I at stations EN and 30 Monitoring Studies,1989
l t i 7 ABLE 7. Annual larval winter flounder abundance indes and 95% emfidence irserval for the Niantic Rivet and Bay as esdmated by the a ' parammer from the Compent function. f Year Niande Rivet Nianue Boy l t 1983 1,863 (1,798 1,929) . 3,730 (3.670 3.791) ; 1984 5,017 (4,884 5.152). 2.200 (2,088 2,311) j 1985 11,924 (11,773 12,075) I,801 (1,717 1,886) ! 1986 1,798- (1,725-1,871) 1.035 - (979 1,091)- 1987 5.381 (5,172 5,590 1,301 (1.240 1,363) 1988 24,003 (23,644 24,364)- 1,785 (1,708 1.861) 1989 .18,587 (17,966 19.208) 1,750 (1,701 1,801) NB, and Stage 4 at station A). A previous compar. flushing to the lower portion of river and into the . j ison between cumulative weekly georectrie means and bay. For Stage 3, a similar pattern in the annual the corresponding a parameters showed them to be abundance was evident at the two bay stations (EN .
'{:
highly correlated (Spearman's rank order correlation and NB), 'Ihe consistency of the relative ranking of coefficient (.I0.999) and that the former was a good years for Stages 1 and 2 at the three river stations and ' i} approximation of the a parameter (NUSCO 1989). for Stage 3 at the two bay stations suggested good. j Abundance of Stage I larvac at the three river stations - precision in the estimation of larval abundance. AI. ; ! In 1989 was the second highest of the 7. year series so, the similar abundance of Stage 3 larvac at EN and . J and probably the reason that abundance of all stages NB cach year suggested that the different sampling combined in 1989 was exceeded only by that for 1988 techniques at the two stations were comparable. j! (Table 7). A comparison among years at each river _ . station showed a similar pattern in Stage 1 abuni The annaal abundance of newly hatched winter i dance, with 1988 the highest, followed by 1989, flounder larvae should be related to adult reproductive : 1 1985,1987,1984,1986, and 1983. The low abun- capacity (egg production) and the number of eggs' . dance in 1983 was partly attributed to undersampling hatching. To examine this relationship, the annual j because of net extrusion (NUSCO 1987), but this egg production estimates (Table 6) were compared to . was rectified in 1984 when a smaller mesh (202 km) the annual abundance of Stage I larvae (Fig.11), I net was used during the early portion of the larval The measure of Stage I larval abundance was the n l season. Stage I larvae were rarely collected in Nian, parameter from the Gompertz function for the Niantic j tic Bay at stations EN and NB, indicating that little, River (st9tions A, B, and C combined). A lineari j l if any, spawning occurred in the bay, Except for a regression indicated a strong relationship between egg - j slightly greater abundance at station A, annual abun. production and Stage 1 abundance, with a significant i dances at the three river stations were similar, . (p=0.0018) positive slope and a good fit (r*=0.93).' [ indicating a somewhat homogenous distribution of 'This relationship showed that the abundance of newly :; Stage I larvae throughout the river, Stage 2 larvae hatched larvac was directly related to the adult repro- l were found also predominately in the river, but were ductive capacity and that egg hatchability was similar - -! more prevalent in the bay compared to Stage 1. In - among years. Also, the consistency of this relation- s! general, the relative annual ranking of Stage 2 abun, ship implied that there.was good precision in thel j dance at the three river stations was similar to Stage sampling of Stage I larvae and, alternatively, that the 1
- 1. This implied a similar rate of larval loss (mor. egg production estimates were a reliable measure of tality and flushing) from year to year during the annual reproductive capacity. ;
period of transition from Stage 1 to 2. Larvae in Stages 3 and 4 of development were generally most - The temporal occurrence of each desclopmentalJ j' L abundant at Station C and their abundance at the two stage in the river (stations A, B, and C combined) and - bay stations (EN and NB) increased to levels similar bay (stations EN and NB combined) was examined by L~ to or greater than stations A and B. During these comparing the dates of peak abundance, which werc later stages of development winter flounder larvac estimated from the inflection point (Eq. 4) of the : were no longer homogeneously distributed throughout Gompertz function (Table 8). Because Stage 1 larvac' % the river. 'Ihe decline in abundance at the upper river were rarely collected in the bay, the dates of peak - ., L stations (A and B) may have represented a gradual abundance could not be estimated for this area. : 9
.WJnter Flounder Studies 31 1
, -, w-, , , - - _-
-w- . . :-.----
1 I; Stage 1 1 l I 30000 - 20000 - i
)
l _ i 10000- - l s z _
~
l - i YEkR 83 N 05 N 87N N 8384 M 8687N R ' B3 N 85 N 87 N 80 83 H 85 M 878888 ' 83 H M N 87N N b Stage 2 t _ i w 10000 -
~~
r r- _r-- 5 1~ $ < ] w _ M ' YEfR 83848586878689 8384 05 N 8708 89 83 84 85 86 87 88 89 83 N B5 8687 88 00 83N05N878689 4000 Stage 3 3000 - ,, [ w 2000 - _ l 6 - l 1000 - _ r , YEkR 83N8586878809 83 84 85 86 87 88 89 83 84 85 86 87 86 89 83848686870808 83 N 860687 H 89 ' 1000 - Stage 4 _ 800-I W g 600 - 400-200 - -. - -
~
M w m "T 1 YEAR 83N8586878889 83 N 8586 8788 89 83 84 85 86 87 88 89 83 N 85868788 89 83NB5N878889 STATON A B C EN NB . Fig.10. Cumulative density by developmental stage for larval winter flounder at each station from 1983 through 1989. 32 Monitoring Studies,1989
i peaked in mid March, but the dates of peak abundance
@" ', a, , ,, in the bay were 15 to 32 days later. Peak abundance t
[ p e** dates during each year in the river and bay for Stage 3 ; [ 1602 , & and 4 larvac, respectively, were similar, except for ,i r . Stage 3 larvae in 1988. Because dates of peak abun- '
,mx dance for older larvae were similar in both the river and bay, but dates for Stage 2 larvac differed consis- !
g tently, this suggested that the larvac were primarily 6* flushed from the river during Stage 2 of development.
$ = m*
15 o . . . Numerous accounts have been given of jellyfish :
'O '5 8. "
preying upon and affecting the abundance of fish lar- ! t00 PFOouciloN [81NATE (X io'l vac. Several species of hydromedusac and the scypho- ! Fig.11. The relationship between the a parameter from medusan Aurelia aurita prey upow herring (Clupca - the Gompertz function for Stage 1 larvae collected in the harcagus)larvac (Aral and Hay 1982 Moller 1984), Niantic River and the annual egg production estimate and laboratory studies with Atlantic cod (Gadus mor-f om 1984 throush 1989. hua), plaice (Plcuronectes platessa), and herring have shown that the capture success by A.aurita increased , For each developmental stage in the river and bay. with medusal size (Bailey and Batty 1984). Evidence annual dates of peak abundance were generally consis- of a causal predator prey relationship on larvae of tent over the 'l year period and ranged between 13 to plaice and European flounder (Platichthysficsus) by 18 days, except for Stage 2. Peak dates for Stage 2 in A. aurita and the etenophore Plcurobrachia pilcus was 1 the river varied by only 8 days, whereas in the bay the reported by van der Veer (1985). Pearcy (1962) stated ! range of dates was 20 days. Stage I larvac generally that Sarsia tubulosa medusae were important predators ' peaked in late February to early March. Based on of larval winter flounder in the Mystic River, CT, and water temperatures of 2 to 3*C during the latter por* had greatest impact on younger, less mobile indiv-tion of February, and egg incubation times reported iduals. Crawford and Carey (1985) reported large num-by Duckley (1982), peak spawning probably occurred bers of the moon jelly (A. aurata)in Point Judith in mid-February, which corresponded to observations Pond, RI and felt that they were a significant predator of spawning adult females In the river, Stage 2 larvae oflarval winter flounder. Medusae of the lion's manc , f Tahle 8. F.stimated dates of peak abundance of larval winter flounder for each developrnent stage in the Niantic River and llay. Year Stage i Stage 2 Stage 3 Stage 4 Niantic River 1983 March 5 March 15 - April 18 May 2 1984 March 7 l March 9 April 24 May 19 1985 March 11 March 16 April 25~ Mayl6 , 1986 February 26 March 11 April 20 May 12 - l 1987 March 10 March 17 April 20 _ May 9 1988 February 29 March 9 April 7 May 1 1989 March 8 Marchl2 April 14 May 11 ~ j Ninntic Hav 1983 - April 7 April 23 1984 May 10 -I April 8 May 4 May 25 I 1985 - April i April 29 May 18 1986 - April 5 April 28 May 11 1957 - April 6 April 28 May 16 1988 - March 24 April 22 May 9 ; 1989 - April 13 April 23 - May 17 Winter Flounder Studies 33
jellyfish (Cyanea sp.), prevalent in collections at sta- go, STAGE 1 tion A, were suspected of being an important predator
~
of larval winter flounder in the upper portion of the 80 Niantic River (NUSCO 1987). Marshall and Ilicks g 43, t (1962) also reported that jellyfish were most abundant in the upper river. In addition, laboratory studies 30 - have shown that wintet flounder larvae contacting the yo, "" tentacles of the lion's mane jellyfish were stunned and ultimately died, even if not consumed by the medusa 10' (NUSCO 1988a). Jellyfish abundance at station A in o,, ,,, ,,,,,,,,,,, 1989 was similar to 1985,1987, and 1988 and r 24 3 3 s 4 4 s s s s s s.s 7 74 e a o e o s , relatively low in comparison to 1983,1984, and 1986 (Fig.12). Coincidentally, three of these years so, 81 AGE 8 (1985,1988, and 1989) of low jellyfish abundance 60' - had the highest abundances of Stage 2 larvac at sta-tion A (Fig.10). But, as previously discussed, a g 4o. similar pattern in the annual ranking of Stage 2 abundance was found at the other two river stations - 80 where jellyfish were rarely collected, Although there g po, _ are numerous reports of predation by jellyfish on lar-val fish, the potential impact of jellyfish predation on 10' larval winter flounder in the Niantic River is as yet o , r9 , ,,O,,,,,,,,., unclear. 2 24 3 O s 4 4.s s 65 s o s 7 7.s e a s e e.s 4o. 3o, STAGES
?' l
- l\ 1 ;! m th' E j 'g ; g 20' _
y : - y -- 6 to f 'I
, W 16' l C .
* 'I / M - -
3 ,/ m f 10 _
,/ j,,, .,
. g s.
, %n; g- .4 'f M 0 .. O........ . .
0 tg tg , i, n- 1
-33 y , - 2 2.5 3 3 s 4 a s s s.s s os 7 7.s a 8.s e e.s 01mR PomR e6APn 94mv DATE ST AGE 4 3o, Fig.12. Weekly mean volume (liters /$00 m3 )of Cyava sp. medusae collected at station A in the Niantic River 25' from 1983 through 1989. _
r 15-Growth and development 5 - g 10 _ The length frequency distribution for each develop- s. _ mental stage has remained fairly consistent since r- i _ staging began in 1983 (NUSCO 1987,1988a,1989). 2 2?$ 5 3's 4 4s s s's s sis i 76 i s's i pIs Again in 1989, larval length frequency distribution LENGTH (mm) showed a separation between the first four develop- Fig.13. length-frequency distribution of larval winter mental stages by predominant 0.5 mm size classes flounder by develcpmental stage for all stations com. (Fig.13). Stage 1 larvac were primarily in the 2.5.t0 bined in Niantic River and Niantic Bay during 1989. l 34 Monitoring Studies,1989
)
3.5 mm size-classes (97%), Stage 2 were 3.0 to larvae were in this and larger size-classes. These dif-4.0 mm (92%), Stage 3 were 4.5 to 7.0-mm (85%), ferences in length-frequency distribution provided addi-and Stage 4 were 6.5 to 8.5 mm (84%). These con- tional evidence that a majority of the larvae hatched in sistent results from year to year indicated that develop- tie Niantic River and some of those that survived car-mental stage and length of larval winter flounder were ly development were gradually flushed into the bay, closely related, which agreed with laboratory findings (Chambers and Leggett 1987; Chambers et al.1988) Larval winter flounder growth rates for Niantic Bay where positive correlations were found between were estimated from entrainment data (station EN). growth and developmental rates. This relationship These data were examined because of the long time-allowed for the approximation of developmental stage series (14 years) available. Weekly mean lengths from length frequency data, over time during a season have a sigmoid shape (NUS-CO 1988a). Growth rates were estimated by fitting A comparison of the length-frequency distributions linear regression to weekly means that showed a con- . i was made between Niantic River (stations A, B, and sistent increase from week to week during the middle C combined) and Bay (stations EN and NB combined) of the larval season (Table 9). A linear model ade-for 1989 (Fig.14). The differences in size class quately described growth, with r2values generally ex-distribution between the two areas were similar to cceding 0.90. To validate this estimation technique, previous findings (NUSCO 1987,1988a,1989) and growth rates were estimated from length data collected consistent with the spatial distribution of develop- at station NB from 1979 through 1989. Annual mental stages (Fig.10). Smaller size classes predom- growth rates were highly correlated (r=0.89; p<0.001) inated in the river, with about 86% of the larvac with those from station EN. Annual growth rates for during 1989 in the 3.5-mm or smaller size classes, station EN were variable and ranged from 0.055 to In contrast, the 5.0-mm size class had the highest fre- 0.099 mm per day. quency in tbc bay during 1989 and over 55% of the Laboratory studies showed that water temperature affects the growth rate of winter flounder larvac NIANTIC nlVEn 4o. - (Laurence 19b; NUSCO 1988a). To examine the
~
effect of temperature on the estimated annual growth 30- rates, mean wate r temperatures for Niantic Bay deter-8 mined from continuous recorders in the Units 1 and 2 5 intakes were calculated for a 40-day period starting at - h 20' the beginning of the week when the first weekly
@ _ mean length was used to estimate the annual growth .
to-I rate (Table 9). A positive relationship (stope=0.013; i p=0.0013) was found between growth rate and water e.. . . . . . . . . . ..... temperature (Fig.15). Based on comparisons of an-22.533.544555.566.577.588.599.5 nual length frequency distribution and developmental stage, growth and larval development were found to N'^" " " ' 20 be closely related (Fig.13). Therefore, if water temperature affects growth rates it should also affect - 33 larval developmental time. The timing of larval peak y _- abundance should be related to the rates of recruitment g _- - and loss (including mortality and juvenile metamor-y _ phosis). Annual dates of peak abundance of larval g - _ winter flounder collected at EN were highly correlated 5-to the mean water temperature in March and April (Fig.16). This agreed with the results of Laurence -
- o. . . . . . . . . . . .%.. (1975). who found that winter flounder larvac 22.533.544.555.566.577.588.509.5 metamorphosed 31 days earlier at 8'C than at 5'C.
""U "
Fig.14 Length frequency distribution of larval winter Annual dates of peak abundance varied by 37 days flounder m Niantic River and Niantic Bay during 1989 during the 14-year period, most likely because of Winter Flounder Studies 35
TABLE 9. Estimated larval wimer flounder growth rates in Niantic Day from data collected at station EN based on linear regression, with 2r values of weekly mean length and mean water temperature during the first 40 days of the time period. Time period Growth rate Mean water b Year included
- mm/ day (S.E.) r2 temperature 1976 March 21.May 2 0.099 (0.005) 0.99 7.0 1977 April 3 June 5 0.075 (0.005) 0.96 6.7 1978 March 26. June iI 0.058 (0.006) 0.92 4.8-1979 March 254une10 0.06) (0.006) 0.90 5.9 1980 March 23 June 8 0.061 (0.003) 0.97 5.9 1981 April 5.May.31 0.075 (0.010) 0.88 1.3 1982 March 28-May 30 0.062 (0.005) 0.94 5.8 1983 March 6-May 22 0.055 (0.002) 0.98 5.2 -
1984 March 25.May 13 0.065 (0 006) 0.96 6.4 1985 March 174une 2 0.057 (0.005). 0.93 6.0 1986 March 30.May 11 0.094 (0.004) 0.99 7.6 1987 March 22.May 17 0.074 (0.007) 0.94 1.0 1988 March 27.May 8 0.086 (0.006) 0.98 7.1 - 1989 March 26.May 7 0.062 (0.008) 0.94 7.0
- Time period of the weekly mean lengths used to estimate growth rate, b
Mean during a 40 day period staning at the beginning of the week that the first weekly mean length was used in estimatmg growth rate. Temperatures were from continuous recorders located in the intakes of Units I and 2. 0.10' Y 78 n' p e 0.0013 e,6 0.09 as MAY, i
- 16 0.08 a,1 U~ 77
& yb . }, MAys" u % 0.07' '
es r9aa0 f j APau I '5 0 0e-7* k lE 28 6 \ ss &. c) r* . l ,pg o .o.n o.ooi ,b ,, l 4 s i i i 'a i 5 i i ME AN WATER TEMPCRATURE MARCH- AP81L WATER TEMPERATURE Fig.15. The relationship between mean water temper. Fig.16. The relationship between the annual date of ature and the estimated growth rates of winter flounder peak abundance (estimated from the Gompertz function) l larvae collected at EN from 1976 through 1989. of larval winter flounder collected at EN and the March-April mean water temperature from 1976 through 1989, water temperature, which differed =opproximately 3*C Growth rates were also estimated for Niantic River during March. April between the earliest (April 16, larvae using weekly mean length data from station C 1976) and latest (May 23,1978) dates of peak abun. with the methods given above for the bay. A mean dance (Fig.16). Despite the wide range in annual annual water temperature was determined for data con. growth rates, a consistent relationship was seen be. tinuously recorded near the mouth of the river during tween length. frequency distribution and stage of devel. a 6.wcek period starting the same week that the first opment (Fig.13). This was consistent with labor. weekly mean length was used in the growth rate cal. atory observations for larval winter flounder as culation. Station C was selected for this analysis be. Chambers et al. (1988) found that at metamorphosis, cause all developmental stages were collected there in age was more variable than length and larval age and abundance (Fig.10). Again, a linear model fit well length were independent. . with r 2values that were 0.95 or greater (Table 10). 36 Monitoring Studies,1989
t I TABLE 10. Estimated larval winter flounder growth rates in Niantic River from data collected at station C based on linear regression, with r 2values of weekly mean length and mean water temperature during the first 6 weeks of the time period.
' lime period Growth rate Mean water Year included
- mm/ day (S.E.) r2 temperature
- 1983 WtMO Niay 1 0.104 (0.007) 0.98 7.8 ..
1984 :h.9 25 May 6 0.102 (0.007) 0.98 6.8 ! 1985 March 31-May 26 0.082 (0.007) 0.95 9.6 19M March 23.May4 0.113 (0.008) 0.98 7.7 1987 March 22.May 10 0 n99 (0006) 0.98 7.3 l 0.98 9.9 l 1988 March 20 May 21 tif W th oc5) 1989 March 26-May 21 0.086 (0.006) 0.97 9.1 ,
- Time period of the weekly mean length used to estimate growth rate, s
- Mean during a 6. week period starting the week of the fint weekly mean length used in estimating growth rate. Temperatures were from a contmuous recorder located at the mouth of the Niantic River.
The estimated growth rates for the river were general- o., ly greater than found for the bay. The growth rates , for latvae in the river were similar to laboratory -
- growth rates of 0.l(M and 0.101 mm per day at mean water temperatures of 6.9 and 7,5*C, respectively f""'
E u (NUSCO 1988a). No positive relationship was appar-ent between growth rates and water temperature, as l z o.io. , was found for larvae in the bay. The possibility of density-dependent growth was examined because the 8 ,, , lowest growth rates occurred in 1985,1988, and , .omoe 1989, which were coincident with the highest larval o.oe . . . . . abundance in the river (Table 7). The a parameter 0 " * * *
- su m m mnwEn>
from the Gompertz function for Stage 2 larvae in the river was compared to the estimated annual growth Fig.17. The relationship between the a parameter from rates (Fig.17). 'Ihe abundance of Stage 2 larvae was the Gompertz function for Stage 2 larvae . and the used because during this developmental stage larvac estimated growth rates of winter flounder larvae collected begin to feed. An apparent relationship between at station C from 1983 through 1989. Stage 2 abundance and annual growth rate indicated density-dependent growth for larval wir.ter flounder in . the Niantic River. Laurence (1977), in a laboratory (1975) demonstrated that the metabolic demands of study on larval winter flounder at 8'C, reported a larval winter flounder increased at higher tempera-decrease in growth rate as prey densities decreased. tures, the growth rate also increased if sufficient food The laboratory study, along with the apparent density. resources were available, and other laboratory studies dependent growth in the Niantic River, suggested that (Laurence 1977; Buckley 1980) have shown that lar-as the number of feeding larvac increased, the amount val winter flounder growth rates depend upon prey of available prey declined to levels less than optimum availability. In Niantic Bay, growth and development
- for growth. correlated with water temperature, but in the Niantic River growth appeared to be density-dependent, pos-
. Slight declines in growth rate caused by less than sibly due to prey availability.
l optimum food, unfavorable temperatures, disease, or pollution can lead to longer developmental times, Afortality l during which high rates of mortality can have a pro-found effect on recruitment (Houde 1987). Buckley Based on length frequency distributions in the river (1982) stated that food availability and water for 1989 (Fig.14) and previous years, it appeared that temperature appeared to be the two most important most winter flounder larval mortality occurred be-factors controlling larval growth. Although Laurence tween the 3.0- to 4.0-mm size classes. For example, Winter Flcunder Studies 37=
there was about a 85% decline in frequency in 1989 e between these size-classes, which included yolk sac x (Stage 1) and first feeding Stage 2 larvac. This initial g . largo decline was followed by smaller decreases for g y? progressively larger size-classes, indicating a reduc- g *a 9- , tion in the rnortality rate after larvac reached the 4.5- - g mm size-class. Pearcy (1962) also reported a greater g
- mortality for young winter flounder larvae (20.7% per y A day) compared to older individuals (9.1 % per day). In ,g a *. k e,2 a laboratory study on winter flounder larvae, Cham-bers et al. (1988) reported that larval mortality was P g _g g g g concentrated during the first 2 wecks after hatching.
Laurence (1977) found that winter flounder larvac had a low energy conversion efficiency at first feeding Iig.18. The relationship between the larval recruitment compared to later development, and that this stage of index (1 g f the ratio of the abundance index for 7 mm and larger lanae to the egg production estimate) for win-development was probably a ' critical period" for mor-talit). Recent research at the University of Rhode Is-River egg production estimated from 1977 through land (Hjorleifsson 1989) showed that the ratio be- g g g 9, tween RNA and DNA, an index of condition and growth rate, was lowest at the time of first feeding of winter flounder (about 4 mm in length) and that these recruitment index, a possibility exists of introducing ratios were afIccted by food availability. The ' critical correlation between the independent (cgg production) period" concept was first hypothestzed by lijort and dependent (recruitment index) variabics. A better (1926) and was discussed by May (1974) for marine approach to identify the presence of density dependent fishes. In many cases, the strength of a year-class is mortality would be a comparison of annual larval mor-thought to be determined by the availability of suf-tality rates to estimates of spawning stock size (i.e., ficient food after yolk absorption is complete. egg production). Larval mortality rates were esti-mated from vata collected from the three Niantic River The possibility of density dependent mortality for stations; data from 1983 were excluded as smaller lar-winter flounder larvae was examined using a function vae were undersampled because of net extrusion (NUS-(Eq. 6) provided by Ricker (1975). Parameters used CO 1987). The abundance of larvac in the 3 mm and were the annual egg production estimates as a smaller size-classes (by l mm size-classes) was used measure of spawning stock size and the a parameter as an index of newly hatched larvae because 3 mm from the Gompertz function for the 7-mm and larger was the approximato length at hatching and the 3-mm larvae collected at station EN. The 7 mm and larger size class was collected most frequently (Fig.14). size-classes were selected as a measure of larval The rapid decline in the frequency of larvac in the recruitment because they would soon metamorphose 4 mm and smaller size-classes was attributed to both into juveniles and collections at station EN were used natural mortality and tidal flushing from the river. since 14 years of data were available. A larval recruit' Hess et al. (1975) estimated the loss of larvae from ment index was calculated by taking the log of the the entire river as 4% per tidal cycle and also deter-ratio of the ct parameter for 7 mm and larger larvae t mined that the loss from the lower portion of the the egg production estimates. This was plotted river was about 28% per tidal cycle. Compensating against egg production estimates and the slope of the for the 28% decline per tidal cycle with two cycles per linear relationship was tested (Fig.18). Although day, the daily abundance estimates of larvae in the there was some scatter around the relatiunship, the slope was significantly (p=0.014) less thaa zero, in- 3 mm and smaller size-classes at station C (located in the lower portion of the river) were rescaled by a fac-dicating that compensatory mortality was occurrmg tot of 1.93. The abundance of larvae in the 7 mm during the winter flounder larval period. s ze class was used as an index of larval abundance just prior to juvenile metamorphosis. Thair abun-A potential problem exists using the above method dance at station C was not adjusted for tidal flushing to identify compensatory mortality. Because the egg because previous studies (NUSCO 1987,1989) have production estimate was used in calculating the larval 38 Monitoring Studies,1989
shown a net import of larvae of this size into the smaller size classes) to each successive I mm size-Niantic River, class. These rates were then plotted against total egg - production estimates (Fig. 20). No apparent relation- ! For the mortality calculations, abundance indices ship existed between egg production and mortality for newly hatched larvae (after adjusting for tidal rates for the 3 mm and smaller size-class to the 4.mm flushing) and for larvac in the 7 mm size class were size-class. For the 3 to 5-mm size classes there ap-determined by summing the mean weekly abundance peared to be a positive relationship, but considerable (three stations combined) during each larval season, scatter was seen in the plot. By the 6-mm size-class - j! Survival rates from hatching through larval develop _ _ a strong relationship was found, suggesting that den-ment were estimated as the ratio of the abundance in- sity dependent mortality or compensation occurred dex of the large larvac (7-mm size-class) to that of the _ during development from hatching through the 4. and smaller larvae (3 mm and smaller size-classes). Total 5-mm size classes, coinciding with the time of first larval mortality for the period of 1984 89 rsnged from _ ' feeding and supporting the " critical period" concept . 84.6 to 97.9%, with a mean instantaneous rate (Z) of previously discussed. 2.92 (Table 11). To determine if density-dependent - mortality in the larval stage could be identified, these annual instantaneous mortality rates were compared to ( es j~ the egg production estimates (Fig.19). A strong M, Er
- relationship was apparent, for when egg production ? as -
increased larval mortality also increased. This rela- 3 8' tionship may have resulted from either density- $ , 7 dependent hatching rates (i.e., egg viability), or from c density-dependent larval mortality rates. _ Because it ! A 8' was shown earlier (Fig.11) that annual egg hatching rates were very consistent, the inverse proportional _{ & relationship between egg production and subsequent ;- larval survival provided further support to the hypoth- i . . . t
'"' '5 8. '
85 ' esis of compensatory mortality during larval devel. [- EGO PRODUCTION ESTNATE (X 10 ') opment. Fig.19. The relationship between'the annual instan. tane us mortality rate for winter flounder larvae collected ' To determine when the larval density-dependent mor, in the Niantic River and the annual egg production'esti, tality was occurring, instantaneous mortality rates - mate fr m 1984 through 1989. were calculated for newly hatched larvac (3 mm and i i l TABLE 11. Estimated larval winter flounder total mortality from hatching to the 7 mm size-class - 1 ANndance indet - Newly 7-mm Total instantaneous f Year hatched
- size class Mortality (%) mottatity rate 1984 6,500 654 89.0 2.30 1985 13,773 452 96.7 3.42 1986 2.483 438 82.4 1.73 1987 6,480 474 92.7 2.62 -
1988 24,561 678 97.2 3.59 i 1989 19,192 394 97.9 216 i mean=2.92
- 3 mm size-class and smaller. -
Winter Flounder Studies 39
i ma mm leasi one tickler chain (the 1-m trawl has two) was
# nearly 100% efficient in catching 70 mm or smaller :
, plaice, a European flatfish similar to the winter S " flounder. However, Rogers and lockwood (1989) to.
g found that by replacing tickler chains with heavy, g y, . spiked chains they nearly doubled the catch of age-O , 3 plaice. Thus, age-0 winter flounder densities reported A herein should be regarded as conservative, minimum g ' 8' g7 - estimates because of unknown gear efficiency. 1 Kuipers (1975) and Poxton et al. (1982) noted that . s.o . . . efficiency of a beam trawl decreased for larger young -
'O 8" 86 *.
in fall and winter because of changes in behavior,' , increased ability to avoid the' net, increased swim ,
- 5**
speed, lowered availability, and perhaps increased
& alertness with age. Therefore, sampling was discon-Ir, ' tinued at the Niantic River stations at the end of Sep.
G is-tember as water temperatures began to decline and just lc 3, before young winter flounder left shallow water, Sampling in Niantic Bay for both 1988 and 1989
] ,
s' ceased earlier during the season because few or no young were found at the two stations. g & A In general, greatest abundance of age-0 winter floun-2 0,, c, ,, ,g _g der in the Niantic River have been found in June, probably when ongoing larval recruitment to shallow ' water habitats is finally exceeded by mortality. Dif-(o, g,, **",
- ferences between the observed dates of peak abundance p .o.oio . for Stage 4 larvae and demersal age-0 juveniles at sta-:
e tion LR during 1983-87 were examined and ranged be-8 **' ' tween 25 and 38 days, but increased to 44 and 48 days - 3 for 1988 and 1989, respectively. These differences R so- may not only have reflected variable developmental 3 time, but also the time metamorphosed young needed l ,,3, , , 37 to move inshore. . Peaks in demersal age-0 winter - flounder abundance at Niantic Bay stations in 1988 and 1989 occurred in late May during the first or 8O io is no 23 s second week of sampling, which was earlier than seen - ego PRooUCTION ESTIMATE (X1o ') in the river. In 1989 at the two Niantic Bay stations, l Fig. 20. A comparison of the instantaneous mortality initially high densities (70-80 young per 100 m2 ) l rates from the 3 to 4 mm size-clriss 3- to 5-mm size- were followed by a continuous decline until few fish chss, and 3- to 6-mm size-class to the egg production remained in July or August (Fig. 21).- In the Niantic estimate for winter flounder larvae collected in the Nian. River, peak abundance in 1989 occurred in late June 1 tic River from 1984 through 1989. at densities (20-30 young per 100 m2 ) that were much 'l below those in the bay. However, abundance de-creased much less in the river to densities of 5 to 10 Post-larval age-O winter flounder fish per 100 m2at the end of the season. Compar. Abundance during summer is n of m ving averages of weekly abundance among stations showed the considerably greater larval meta-Newly metamorphosed young-of-the-year winter m rPhosis in Niantic Bay as opposed-to the river flounder were collected using a 1-m beam trawl. (Fig. 22). However, apparently greaterlosses of post-Kuipers (1975) reported that a 2-m beam trawl with at larvae occurred in the bay. The number of young 40 Monitoring Studies,1989
" too " 18 RM - 1989 BP - 1989 E
g l40 gi40 120 120 too N 100 80 80 go g oo \ l 40 o. . MAY JUNE JULY AUGUST SEMEMBER l 40 - o. WAY JUNE t JULY AUGUST SEPTEMBER
" 40 LR - 1989 " ~
E 8 8
" 30 '
' 3o
./ \ !
20 \ $20 l Y\ lto
/~~y ~j x /
+\
l 10/ MAY JUNE JULY (t AUGUST SEMEMBER I, ' MAY JUNE JULY tH'\ AUGUST SEPTENBER i Fig,21. Weekly mean CPUE (12 standard errors) of age.0 winter flounder taken in Niantic River and Bay during 1989. 110-g 100* [ d>- b 90- / > 7 ._ t h,ws] 80- /
/
\
l Cg RM/ \ l l gg 70- BP ti M Oo so- 4 s .
\g g 50-
- a. \
r 40- \ eo \ gh 30-o % 20-2h 10- N s " WA o.,LR ' , '~~- _, ~ MAY JUNE . JULY AUGUST SEPTEMBER Fig. 22. Moving average of weekly mean CPUE of age 0 winter flounder taken in the Niantic River and Bay during 1989. Winten Flounder Studies 41 I l
a 2 (TABLE 12. Seasonal I.m beam mwl median CPUE (number per 100 m ),g ,, .o. winter flounder at two stations in the lower Niantic River (LR and WA) from 1983 through 1989 and two stations in Niantic Bay (RM and BP) during 1988 and 1989. Coefficient
- Survey . Tows used Median 95% confidence of 9 year
- Station Season' _ for CPUE CPt2 interval skewness
1983- LR Early 30 32.7 20.0 50,7 2.29
'IR late 27 10.0 8.0 13.3.- 0.49 1984 1R Early 40 18.8 'l6.7 25.0 0.63 1R late 36 - 6.3 . 38-7.5 0.58-WA late 32 11.3- 8.0-17.5 0.94 :
1985 LR Early 40 _13.3 - 10.0 16.3 . 0.91 LR ' late 32 7.0 6.0 8.0 0.97- . WA- Early 40 15.0 10.0 20.0- 0.81 - WA late 32 9.0 ' 8.0-10.0 -0,70
-1986 1R Early 39 '33.8 23.3 40.0- 0.33 IR late 36 13.8 - 12.5 17.5 0.80 -
WA' Early 40 21.7 12.5 26.7 , 1.49 WA late 36 18.1 15.0 20.0 2.03
-i 1987 LR Early ;. 40 59.2 53.3 73.3 0.12 LR tate ' 36 17.9 12.5 26.7 - 0.70 -
WA Early 40 28.3 21.7 38.3 0.27 ~ WA late 36 10.6 6.0 13.8 0.83 1988 1R Early 40 - 61.3 52.5 72.5 - 0.37 . tR . late -- 36 60.0 50.0 70.0 . 1.17-WA Early 40 40.0 32.5 51.7 0.13 WA Late 36 38.3 33.3 51.7 0.22 RM Early 39 47.5 30.0 72.5 3.68 RM tate 36 7.0 6.0-8.0 0.20 BP - Early 40 71,3 32.5 107.5 - 1.17 BP Late 32 ' l.6 1.0-3.0 ' O.99 i- 1989 IR Early 40 '17.5 11.7 21.7- 0.09 l IR- Late 36- 8.8 7.0 11.3 0.84 p' WA Early 40 10.0 8.3 13.8 1.16 - , l WA Late 34 5.5 .4.0 10.0 0.66 RM Early 40 50.8 26.7 75.0 0.64: RM late 32 0.0 0.01.3- 1.79 IlP Early 39 20.0 6.3 32.5 1.78 BP Late 12 0.0 -0.00.0 3.46
' For age-0 fish, the year class is the same as the survey year, b
Early season corresponds to late May through July and late to August through September. -
- Zero for symmetrically distriluted data.
1 winter flounder remaining in the two areas sampled in -1989 year class of winter flounder may be relatively . Niantic Bay at the end of summer seemed inconsequen- weak. Year-class strength is probably influenced con-tial in comparison to the population in the river, siderably by events during the first summer following . metamorphosis, even though greatest mortality oc-- When compared to previous years, densities of curs during larval development. The median density . young in 1989 at LR and WA were lower than during of age-O winter flounder during August and September 1986-88, particularly during the second half of the may yet prove to be a reliable measure of future adult season (Table 12; Fig. 23). This indicated that the abundance. However, because this particular 42 Monitoring Studies,1989 I
i
.i i
~$
1 100- Station WA -
- ?
gf90- ! 1a N 2 80-Du q fO ,70- i W $ 60-
%o-
- a- :)
o 6; 50' -,- U n. .
-e .t z SS- '
o o p 30: +
*g 20- , _
s ,, 5
~
\
-'s c 86 g to
- ----- -. g g :
0- . ' ' ' ' MAY JUNE JULY ' AUGUST' - SEPTEMBER 100' Station LR ' t 0' , b
, s 80- .
bu , h!70-3: o F Ld $ 60-bo w 88-og l 50- ., U n- .<
-e 40-z ;
- o "
0 Q 30-Z L /,,--- sq's , 37-
..v x 20- / s----
s ,
,/,/ 'ss - _- ----
86. gg I 0-
?
MAY JUNE JULY -AUGUST SEPTEMBER : ' Fig. 23. Moving average of weekly mean CPUE of age-O winter flounder taken in the Niantic River from 1986 through 1989. , Winter Flounder Studies ~ ; 43 -
?
5
l l sampling program began in 1983 and complete recruit- surface, the difference between this station and the ment to the Niantic River adult spawning stock may shallow water LR station would likely have been not occur until at least age 5, little data are yet even greater at the bottom, where juveniles resided, available to confirm this relationship. The difference between RM and LR varied between about 1.5 to +1.5'C; this probably reflected varying L Growth '. water masses originating in the river or bay, depen-ding upon the tidal stage sampled at RM. Because Apparent growth of young was noted by obscrying . growth was generally slower in the bay than in the changes in weekly mean length, in the Niantic river during the first half of the season,it was unlike. River, after a relatively rapid increase in weekly ly that densitics at LR and WA were supplemented by means from May through July,little change occurred an influx of fish from the bay (Fig. 25). No apparent throughout the remainder of the summer, particularly changes in length frequency distributions, mean at WA (Fig. 24). Growth was less variable than lengths, or variability occurred that would have been abundance as the weekly means had relatively small likely if many smaller fish continuously joined the confider.cc intervals. Differences in mean growth initially faster growing fish in the river, between the stations were apparently greater in 1989 . than during 1987 88, when no significant differences Growth differences between the bay and river sta-were found between stations; greatest differences oc- tions were perhaps due to the warmer water found curred in 1984 and 1985 (Table 13). Water tem- within the river, particularly in spring and early perature was usually 0.5 to 1.0*C cooler at LR than summer when growth was most rapid. Environmen. WA, most likely due to the influx of Niantic Bay tal factors such as benthic food production and avail- l water as sampling took place at the former station ability may have differed among areas and also would l during the second half of flood tide 'and at the latter have affected growth. S9ucerman (1989) found sig-near high tide or during the first part of the ebb, nificant differences in abundance, mean length, and I length-weight relationships for young winter flounder Patterns of growth differed at the Niantic Bay sta-s among different habitats in Waquoit Bay, MA. Areas tions, where steady increases in weekly mean length adjacent to eclgrass (Zostera marina) were particularly were observed throughout the season (Fig. 24); - conducive to greater growth. Both food preferences Weekly metms were smaller for fish taken in the bay and rates of feeding were considered important factors than for those resident in the Niantic River. in the growth of young plaice (Steele and Edwards llowever, although not shown on the figure because 1970; Poxton et al.1983). A tentative explanation j of the small weekly sampic sizes, the few fish for the differences observed among years for station - remaining at RM in late August nnd September were LR is density-dependent growth, which has been particularly large (62 70 mm) relative to those in the regularly observed in juvenile fishes (Cushing and river. Water temperatures were consistently 1.5 to Harris 1973; Ware 1980; Poxton et al.1983; van der 2.0*C colder at BP than LR. As the temperature at. Veer 1986). Significantly larger means were found BP (average depth of about 7 m) was measured at the - for 1983 85 and 1989 (Table 13) when densities were 3 TABLE 13. Mean length of age O winter flounder taken at stations LR and WA in the Niantic River during late July through September of 1983 through 1989. Mean j length (mm)*: M 59 58 57 H 51 50 g 46 45 g 42 42 - , l Station IR 1R tR' tR 1R WA- WA WA tR 1R WA. WA -WA Year 83 84 89 85 88 88 89 87 86 87 84 85 86 Difference between seasonal mean at IR and WA: Year 84 85 86 87 88 89 Difference (mm): 16 15 4 2 o 8
- Means underlined not significantly different (p 5 0,05).
44 Monitoring Studies.1989
i go. Niantic Bay stations - 1989 70* 3 60-a g 50- ,
<7 z.,
RM --- # Q 40- j ' b 3
-YY 7
30-1 20-10- gp 0- . - MAY JUNE JULY AUGUST SEPTEMBER gg, Niantic River stations - 1989 70-LR 5 gg. / 4 /\. s a O, m g 50- %}ll/ 40-h WA --- 3 30-D 20-10-0- . - MAY JUNE JULY AUGUST SEPTEMBER l Fig. 24. Weekly mean length (12 standard errors) of age 0 winter Counder taken in Niantic River and Bay during 1989. Winter Flounder Studies 45
-(CT DEP) also indicated little or no movement of young from one area of the river to another nearby so area (P. Howell, CT DEP, Waterford, CT, pers.
] yo comm.). Most likely, ocither large scale movements x tR away from any station not differential movements by 5 ,, f / % WA size occurred throughout most of the summer, g so Ru - 3 40 Mortality
- J **
> ,,/
p Catch curves were constructed using annual abun-dance data to determine instantaneous mortality (Z) and weekly and monthly survival rates (S). This
* ~ WAY JUNE jut.Y AUGUST SEP7EWBER method assumed that young comprised a single age cohort that was followed from week to week during the sampling season. Catch curves constructed had -
Fig. 25. Comparison of weekly mean lengths of age.0 relatively good fits (with one exception) and had r2 .. winter flounder taken in Niantic River and Bay during values ranging from 0.67 to 0.93; the fit to the data 1989. in 1985 at WA was not as good (r2=0.51). No sur-vival estimates could be generated for LR and WA lowest (Table 12). Changes in the eclgrass beds during the high abundance year of 1988 as the slope along with accompanying sediment changes were also of the catch curve was not significantly diffuent from qualitatively noted at and near station LR during the zero(NUSCO 1989). years of study (see Scagrass section elsewhere in this report for additional information).' Apparent annual Monthly survival estimates for 1989 were similar ; changes in growth may also have Ir:en caused by dif- at LR (0.581) and WA (0.576; Table 14). Over the forential movement of larger young away from the period, annual estimates of survival were more station, which also would increase the apparent mor- variable at WA and generally were lower than at LR, tality rate. However, few young were taken during . - As expected from the decline in catches, apparent sur-the summer at trawl monitoring program stations. A vival rate at the Niantic Bay stations, particularly BP, limited marking study of age O winter flounder by the was considerably less t_han in the river. No fish Connecticut Department of Environmental Protection remained at BP or RM at the end of summer in 1989. TABIE 14. Monthly survival rate estimates as determined from catch curves for age 0* winter flounder taken at two stations in the lower Niantic River (t.R and WA) from 1983 through 1989 and two stations in Niantic Ilay (RM and HP) from 1988 through 1989. MontMy survival rate rSi at statinn: ! Survey year
- IR WA RM BP I-1983 0.552 - - -
1984 0.571 - - . 1985 0.599 0.694 - - l- 1986 0.576 0.356 (early) . - l 0.440 (late)* 1987 0.626 0.547 - - 1988 AS' AN' O.400 0.179 l 1989 0.581 0.576 0.166 0.122 Average survival rated 0.584 0.509 0.258 0.148 i
- For age 0 fish, the year class is the same as the survey year.
- l. 6 Data partitioned because of increase in abundance at station in mid. summer; estimates inay be unreliable.
' Stope not signir.cantly different from zero, d
Detennined from the average of the correspondmg estimates of instantaneous mortality rate Z. 46 Monitoring Studies,1989
)
The apparent survival rate at RM declined from 0.400 ably have not varied enough to clearly demonstrate : in 1988 to 0.166 in 1989. Greater mortality in Nian- density-dependent mortality, although densities were = , tic Bay may be related to the generally smaller size of apparently different enough to have affected rates of - ' young and the greater numbers of fish available to - growth. Based on declines in density, mortality of ; prey upon them in these deeper areas. This may be young winter flounder appeared to be greater in the analogous to the case of age-0 plaice in Europe, early part of the season, except for the 1988 year. where mortality in the shallow inland Wadden Sea of class. The sand shrimp (Crangon Jeptemspinosa), , The Netherlands was less than that found for plaice related to the European brown shrimp, was common. < inhabiting the more open and deeper British bays,- ly observed at all winter flounder stations, with larger which had more fish predators (Bergman et al.1988). individuals particularly abundant in the Niantic River > Monthly survival rates in the Niantic River were less early in the season, This species has the ability to than the value of 0.69 reported by Pearcy (1%2) for feed on newly metamorphosed winter flounder- l the Mystic River estuary; survival rate estimates for (Whitehouse 1989) and was suggested by Jeffries et - young plaice in British coastal embayments were al. (1989) to prey upon larval and metamorphosed about 50% per month (Lockwood 1980; Poxton et al, winter flounder in Narragansett Bay. Modlin (1976) 1982; poxton and Nasir 1985). reported that adult (>40 mm) sand shrimp in the . Mystic River, CT moved into shallow (<1 m) water Adult recruitment for many fishes is greatly affected during their April June reproductive period. Abun- ; by density dependent processes occurring during the dance of adult sand shrimp in this estuary was about ! first year of life following the larval stage (Bannister 4.6 to 6.5 per m 2during these months, but numbers ' L et al.1974; Cushing 1974; Sissenwine 1984). No rapidly decreased when water temperature increased , evidence was found for density-dependent mortality of above 18'C. This period also coincided with greatest - post larval Niantic River winter flounder as apparent mortality of age-O winter flounder in the Niantic' i survival rates wete highest in 1987 and 1988, when River. Similar to the plaice and other flatfishes (Roff - densities were greatest. Bannister et al. (1974),. 1931), the largest year classes of winter flounder in ' Lockwood (1980), and van der Veer (1986) all the Niantic River (NUSCO 1989), Narragansett Bay reported density-dependent mortality for young plaice. (Jeffries and Terceiro 1985; Gibson 1987; Jeffries et. liowever, examination of their findings indicated that al.1989), and in southern New Jersey (Danila 1978) - greatest rates of mortality occurred only when were associated with extremely cold winters. The ex-U extremely large year classes of plaice were produced tent to which predation by sand shrimp affects young
,( three to more than five times larger than the aver- winter flounder numbers is yet uninown, although age). van der Veer and Bergman (1987) and Bergman Moore (1978) noted large reductions in the number of et al. (1988) suggested that much of the mortality of . sand shrimp in Barnegat Day, NJ as a result of the newly settled plaice in the Wadden Sea of The Nether- severe winter of 1976-77; this winter coincided with-lands was due to predation by the brown shrimp - the production of the strong 1977 year class of winter -
(Crengon crangon). The shrimp predation was den- flounder in .both New ' Jersey' and Southern New > l sity dependent and continued until plaice grew to England. I about 30 mm in May, Densities remained fairly con-l' sistent thercuiter until September when the young Abumfance during latefall arul early winter ,
- plaice emigrated to deeper water. They also noted that '
the production of strong year classes of plaice during . As water temperatures decrease in fall, young win-years with cold winters may have been due to substan- ter flounder disperse from shallow waters near the - i tial decreases in brown shrimp abundance, Following shoreline to deeper waters and consequently become L severe winters, brown shrimp that had emigrnted out '
. available to the otter trawl used in the year-round of the estuary before winter delayed their return be- trawl monitoring program. Generally, young were cause of the cold water temperatures. Many shrimp first taken by otter trawl at the shallow inshore sta-that remained inshore either died or also emigrated off-tions (NR and JC) adjacent to their nursery grounds in - i shore. Thus, predation pressure on the newly meta- October or November, the near-shore Niantic Bay sta; morpimed plaice was lessened under these conditions, tions (IN and NB) in December, and at the deeper-water stations in LIS (7T and BR) in January.- Using -
The numbers of metamorphosed young winter trawl monitoring program catch data beginning with q flounder found in the Niantic River since 1983 prob. Winter Flounder Studies 47:
e these months and continuing to the er d of February, a than those taken during preceding months by 1 m ]
&mean (NUSCO 1988b) index of relative abundance beam trawl. This size difference was greater than was developed for these age 0 fish. This period fol- would have been expected by growth alone and, most lowed the summer beam trawl sampling and was prior likely, biased CPUE indices as smaller individuals to the catch of the same fish present as age 1 were scemingly cxcluded from the catch. 'Ihe fixed juveniles during the effort intensive adult winter locations of the otter trawl sampling stations in rela- ,
flounder surveys in the Niantic River from late tion to the habitat available to juveniles may also February through carly April. The 1988-89 &mcan have affected catches. Movements of smalljuveniles ; of 29.6 was the largest of the 13 year series and was ' were likely governed by factors such as water temper. another indication of the strong year class produced in ature and tide, and their availability to the sampling 1988 (Table 15). Since 1983, when comparable data - gear in fall and winter varied from week to week and were available, the fall carly winter &mcans generally year to year, depending upon conditions. Relatively corresponded with the preceding late summer 1 m beam trawl densities at stations LR and WA in the Niantic River (Fig. 26). Ilowever, little correspon- g 70 dence was seen over the 13 years between the &means ,, t and median CPUE of winter flounder smaller than 15 NR BEAM TRAWt. MEDIAN (-~~) cm taken in the Niantic River during the subsequent 50 late February carly April adult winter flounder survey g 4o (Fig. 27). Although similar trends were seen among
@3 wm(
5 ) these three catch indices, none of them were. significantly correlated (see Table 20 below). 20 , Any possible relationship among abundance indices of juvenile winter flounder may have been obscured oj, 77 j, j, ,, ,j ,, ,3 ,, ,3 ,, ,, ,, ,, by sampimg vanability. The selectivity of fishing YEAR-CLASS gear is a major source of bias in abundance estima-tion, including size selectivity of the gear, spatial distribution of individuals in relation to the gear, and Fig. 26. Comparison between the 1976 88 late fall, behavior of fish in the vicinity of the gear (Parrish early winter seasonal 8-mean CPUE of age-0 winter 1963). Mean lengths of age-0 winter fiounder taktn fl under for the trawl monitoring program (TMP) and the - by otter trawl in fall were about 15 to 25 mm larger 1983-88 late summer Niantic River age 0 beam trawl-median CPUE. TA!!!.E 15. He late fall-carly winter seasonal
- 6.mean CPUE of age.0hwinter flounder taken at the six trawl monitoring stations in the vicimty of MNPS.
Survey yearb Number of samples Kon rero observations 6-me'an 95% confidence interval 1976-77 42 36 6.1 2.0 10.3 1977 78 42 38 5.1 2.37.9 1978 79 42 36 4.2 2.06.4 1 1979 80 42 38 4.2 2.26.2 ( 1980 81 40 37 10.7 4.2 17.2 1981 82 40 38 8.1 2.9 13.3 1982 83 38 36 21.8 10.0-33.6 i 1983 84 40 37 6.7 3.3 10.2 l 1984 85 36 32 8.9 2.0-15.6 1 1985 86 36 36 8.6 5.7 11.6 1986 87 36 33 13.4 2.0 24.8 l 1987 88 36 35 4.9 1.6 8.2
- l. 1988 89 42 41 29.6 11.8 47.3
- Data seasonally restncied to November. February for NR and JC. December February for tN and NB. and January February for TI' and BR.
6 l For age 4 fish, the year. class is the same as the first par giyen. I 48 Monitoring Studies,1989 l l I
1 a 1 l h CPUE of small winter flounder (Table 16) were g NR WFS MEDIAN (---) more variable than those for adult fish (Table 2),
,, Abundance was greatest in 1981 (71.1) and declined tof 3 a low of 4.1 in 1986. The 1989 value of 7.9 (1988 - ;
year class) represented a decline from the 1988 median -'
- u. " e of 11.2 (1987 year-class). This was particularly
; disappointing considering the large number of young of the 1988 year class seen during the previous sum.
30
' mer in the Niantic River and during late fall early l 20 , M- winter period at the trawl monitoring program-iE
- V - r 9 stations. This low juvenile abundance index seem-is n is to o a e2 as a4 es as e7 sa as N P N Y" "* **
because the behavior ofjuverule winter flounder large-YEAR-CtASS ly mfluenced thett availability to sampling, this par- ' ticular abundance index has not been considered a reli-Fig. 27. Comparison between the late fall.carly winter able measure of year-class strength (NUSCO 1988a, seasonal 6 mean CPUE of age.0 winter flounder for the 1989). The magnitude of the CPUE index and the trawl monitoring program (TMP) and the Niantic River trends in abundance for these fish also depend upon survey median CPUE (WIS) for winter flounder smaller the particular data used to calculate the index. For-than 15 cm from 1976 through 1988. example, it was shown previously (NUSCO 1988a, 1989) that combining catches of age-1 winter flounder large confidence intervals around the S-means were fr m tows made throughout the river with those made-probably an indication of this variation. This was in only in the lower river navigational channel changed ' contrast to the summer sampling by the relatively ef. the comparability of annual median CPUE values - ficient beam trawl that took place during a fixed tida (Table 17), Differences in annual medians were stage in areas known to be preferred habitat for young smaller in years when fish were concentrated in the winter flounder Finally, a mixture of juveniles from channel. . For example, the 1989 CPUE of 6.1, ob-a number of different source areas most likely tained when catches from the entire river were used, occurred throughout LIS during the winter, and this was the largest CPUE computed since 1985 (13.3). could also have biased the measure of abundance, During 1986,1987, and 1989, catch data indicated a depending upon the variable contribution of the dif, more uniform distribution throughout the river. As ferent stocks. distribution over the entire river became more l uniform, concentrations in the lower river channel l most likely decreased. This may have biased abun-Age-1 juvenile winter flounder dance estimates based on tows from only that relatively small area of the river. Abundance during the adult spawning season The correspondence between the abundance of Small winter flounder have been taken incidentally juveniles in the Niantic River to those found in Nian-during the February-April adult winter flounder sur- tic Bay apparently also varied from year to year (NUS. l veys in the Niantic River from 1976 through 1989. CO 1989). In contrast, adult fish were concentrated An annual median CPUE was calculated for fish almost entirely within the Niantic River each spawn-smaller than 15 cm, which were mostly age-1 and ing season with relatively few individuals found in-l represented the year class spawned during the previous Niantic Bay at the same time. A S-mean abundance - year. Adjustments made to the catch data were sim- index for winter flounder smaller than 15 cm taken by ( ilar to those previously discussed for adult fish. For the trawl monitoring program fun January through some annual comparisons, data were restricted to sta. April at stations outs.w, . the Niantic River was tions 1 and 2 because small winter flounder were compared to the CPUE median for the river (Fig. generally less abundant than adult fish in the upper 28). A longer time span was chosen for the trawl river, where no tows were made from 1977 through monitoring program data to increase sample size and 1980. to overlap the spawning period. Overall, the catch of . these mostly age-1 winter flounder in the winter and Winter Flounder Studies 49
, y y
TABLE 16. Annual 9.1 m osier trawl adjusted median CPUE of winter flounder smaller than 15 cm' taken in the navigational channel of the - lower Niantic River during the 1976 through 1989 adult population abundance surveys. Tows Adjusted . Coefficient Survey . Weeks accepteble menber of - Median 95% confidence of year * , _ sampled forCPUE6 tows used' ~ OMI interval - skewnessd-1976 -7 98 154 20.0 19.0 20.0 2.77-12.0 17.0 ' 1977 6- 166-- 2;9 13.5 1.50 1978 6 129 156 21.6 15.0 25.0 1.59-1979 5 107 136 41.0 27.0 66.3 2.82 1980~ 5 110 145 49.3 34.5 62.6 1.30 1981: 7 93 140 71.1 55.0 84.8 0.79 1982 5 50 -- 70 34.4 13.2 52.5 1.46 i 1983' 7 77 77 43.0 33.0-58.8 0.55 - 1984 7 72- 77 18.5 14.2 20.8 .2.23 1985 7 82 84 23.6 18.4 28.2 1.27 1986- 7- 72 118 4.1 . 2.75.3 1.57 1987 5 41 50 5.0 4.36.7 2.08 1988. 6 49 54 11.2 7.7-15.7 1,38 1989- 7 50 - 54 7.9 4.0-11.9 1.19
- Mostly age.1 fish, so predommant age. class was produced 1 year before the survey year, j 6
Only tows of standard time or distance made in the navigatic. mal channel of the lower river were considered. ;
- Elfort equalized among weeks.
d Zero for symmetrically distributed data. i
.I , TAliLE 17. Compariscn of annual 9.1-m etter trawl adjusted median CPUE of winter flounder smaller than 15 cm' taken in the navigational ,
I channel of the lower Niantic River with those caught throughout the entire samphng area of the river during the 1976 through 1989 adult population ahimdance surveys. Naviaational channel oniv: Fa'% area of river 3====1 d: Adjusted Adjusted Survey number of Median Coefficient of number of Median Coefficient of.. year-a tows used h CPUE- skewness' tows used* CPUE skewness' - -j 1976 154 20.0 2.77 231 14.4- : 2.84_ j 1977 229 13.5 1.50 Insufficient tows made in upper river l 1978 156 21,6 1.59 Insufficient tows made in upper river ; 1979 136 41.0 2.82 Insufficient tows made in upper riv c i 1980 145 49.3 1.30 Insufficient tows made in upper river 1981 140 71.1 0.79 182 14.0 1.64 - 1982 70 34.4 1.46 118 8.7 - 2.40 1983 77 43.0 0.55 238- 11.5 1.80 1984 77 18.5 2.23 287 64 4.08 1985 84 23.6 1.27 280 13.3' 2.36 1986 118 4.1 1.57 336 4.0 1.47 1987 50 5.0 2.08 270 3.2 2.46 j 1988 54 11.2 1.38 312 3.7 3.03 ' 1989 54 7.9 1.19 318 6.1 1.64 i a Mostly age.1 fish. so predominant age-class was produced 1 year before the survey year. -j b Effort equalued among weeks. J
- Zero for symmetrically distributed data.
l 50 Monitoring Studies,1989 l l,
- i l
Thus, a small CPUE index in the river may not. iecessarily indicate a continued decline in abundance, ' d 80 because even a relatively small increase in catch for 80 NR WFS WEDIAN the much larger geographical area of Niantic Bay 70 would compensate for a concurrently low abundance 60 in the river. This, however, assumes that most of the b 50 - fish taken in the bay are from the Niantic River , 40 / stock, which may not be the case. In conclusion, the 30 m differential distribution and abundance of age-1 juv. 20 / j. eniles associated with the adult winter flounder sur-to }.--}.-[ Y-[ D s/
}
b' veys and the trawl monitoring program catches have ; o mPf-MEAN - made their abundance indices a generally unreliable ' 76 77 78 79 80 81 82 83 84 85 86 87 88 89 prediClor of future adult population size. YEAR (JANUARY-APRIL) Comparisons among life-stages of winter Fig. 28. Comparison between the annual January April flounder year Classes , 6.mean CPUE for the trawl monitoring program (TMP) and the Niantic River survey median CPUE (WFS) for A summary of the abundance indices for various nier flounder smaller than 15 cm from 1976 through life-stages of the 1976 through 1989 year classes of winter flounder discussed previously is given in Table ,
- 18. If indices for all life-stages were accurately and early spring fluctuated less outside than inside the precisely measured each year, then they should be cor.
Niantic River. As the number of small fish in the related after applying appropriate time lags, except , river declined to historic low levels in 1986 and 1987, when some process (e.g., density-dependent mortality the number outside the river increased. In 1988, catch or size-selective fishing) results in lack of linearity within the river increased as catch outside the river between two consecutive life-stages. ' Successful I decreased. This trend reversed in 1989 as catch in the linkages were made only among a few life-stages, bay was the second highest of that series and showed ' including parental stock, egg production, and Stage I that most juveniles did not remain within or re-enter 1 tvac (Tables 19- and 20). In most instances, the Niantic River during the 1989 spawning season, however, no correlations were found between succes- , sive stages because of inconsistent changes in annual
~
TADt.E 18. Comparism of indices of abundance for various lifetages of winter flounder for the 1976 through the' 1989 year-classes, larval aNmdance (Feb-Junei . Juvenile abundance Age 1 River stations Intake . tower Lower River fish Female Year- Egg Stage I Suge 2 Stage 3 Stage 4 (bay) river river . : and bay (river) spawners class production (3 mm) (3.5 mm) (6 mm) (7.5 mm) (7+ mm) (May Jul) (Aug-Sep)(Nov-Feb)(Feb-Apt)
- 76 - - - 854 - -
6.1 13.5 884 77 394.6 - - - - 567 - - 5.1 21.6 1,412 78 717.5 - - - - 754 - - 4.2 ' 41.0' 1,120 79 535.3 - - - - 641 - - 4.2 - 49.3 903 80 424.3 - - - - 845 - - 10.7 71.1 2,669 81 1,383.1 - - - - 561 - - 8.1 34.4 2,752 82 1,596,8 - - - - 610 - - 21.B~ 43.0 1,869 83 1,082.0 - 749 408 56 1,215 32.7 10.0 6.7 18.5 871 84 501.6 2,601 1,501 573 67 917 18.8 6.3 8.8 23.6 1,082 85 659.5 6,260 4,676 584 35 312 13.3 70 8.6 4.1 655 86 436.7 1,279 176 301- 24 510 33.8- 13.8 ' 13.4 5.0 , 852 87 531.6 3,218 829 1,036 48 315 $9.2 - 17.9 4.9 11.2 1,279 88 866.9 14,491 4,469 1,531 210 419 61.3 60.0 29.6 7.9 984 89 716.2 12,463 3,976 ~589 73 327 17.5 8.8 - - l l
' Winter Flounder Studies 51
,a TADt119. Matrix of Spearman's rank order correladons among various winter flounder spewning stock and larval abundance indices.
Nianne River Niantic River Niantic River Niande River Niantic River MNPS Intake addi egg Suge 1 Suge 2 Suge3 Suge 4 larvac Index* production tarvac larvae larvae larvae G+ mm) Niantic River 0.8846' O.8857 0.42166 0.2143 0.5000 0.2363 female 0.0001 " 0.0188
- 0.3374 NS 0.6445 NS 0.2532 NS 0.4371 NS -
spawners 13 6 7 -7 -7 33 Niantic River 1.0000 0.3214 0.3571 0.5714 0.0055 - aduh egg <0.0001 " 0.4821 NS 0.4316 NS 0.1802 NS 0.9858 NS production 6 7 7 7 13 Niantic River 0.7714 0.8286 0.7714 0.4286 Stage 1 0.0724 NS 0.0416
- 0.0724 NS 0.3965 NS larvae 6 6 6 6 Niantic River 0.6429 0.4286 0.6071 Stage 2 0.1194 NS 0.3374 NS 0.1482 NS latvae 7 7 7 Nianue River 0.6071 0.5714 Stage 3 0.1482 NS 0.1802 NS larvae 7 7 Niantic River ' O 1786 Stage 4 0.7017 NS c larvae 7
* ~.ndices used correspond to those given on Table 18.
- Shown for each Speannan rank order correlanon:
1 correlation coefficient.
- l. probabihty level (NS - not significant. ' significant at p 5 0.005, " significant at p 5 0.01), and number of annual observations (sample size) abundance for which compensatory processes seemed Recruitment and year-class Strength an unlikely explanation. Some lack of correlation may have been related to sampling, because fixed Winter flounder were proportionally allocated to age-locations and time of samplir.g did not take into con- classes I thrcugh 5 and a last class of fish age-6 and sideration environmental effects and behavior of win- older using an age-length key described in NUSCO ter flounder that could introduce cot.siderable vari- (1989) that was applied to annual standardized catches.
ation. Although negative correlations were found This key gave mean lengths-at age similar to those between the abundance of 7+ mm larvac with egg reported for eastern LIS and Rhode Island winter production end with each of the first three larval flounder (NUSCO 1989); growth among these threc . stages, none was significant. This is consistent with groups of winter flounder was found to be not sig-thc existence of density-dependent effects during the nificantly different by Gibson (1989a). The cembers larval stages discussed previously. Connections of fish in each age group for all annual standardized among abundance indices of winter flounder within catches (1977-89) were summed to give a 13-year the same year class are of considerable interest for average age class (Tabic 211 column labeled " observed impact assessment. The earliest possible measure of abundance"). 'Ihis was compared to expected numbers relative year chtss strength is desirable as this would of female spawners, assuming an instantaneous mor-enable predictions concerning future recruitment to tality rate of 0.85 from age-3 through age-15. The the adult stock and, thus, provide an early warning of comparison suggested that, on average. 82% of age-3 recruitment failure, females,60% of age-4 females, and 14% of age-5 52 Monitoring Studies,1989 f a f
-e t.
e u h l TABLG 20. Matrix of Spearman's rank. order correlations among various larval and Juvenile wmter flounder abundance indices. Niantic River lower river Lower river Fall.early winter . Niantic River. [ Stage 4. carly age.0 - - late age.0 - river. bay , winter. spring ;
.Index' larvae juveniles juveniles . . juveniles . age.1 juvenlics 4
MNpS intake 0.1786 6 l 0.2143 .0.0714 -0.1678 - 0.5385 larvae 0.7017 NS 0.6445 NS 0.8790 NS 0.5837 NS 0.0576 NS (7+ mm)~ ~7 7 -7 '13 13
. Niantic River 0.1786 - 0.1071 -0.2571 0.6000 -
Stage 4 0.7017 NS 0.8192 NS 0.6228 NS 0.2080 NS . larvae 7 7 6 6 lower river 0,8929 0.2571 0.0286' 0.0068 " 0.6228 NS 0.9572 NS ! early age.0
- juveniles - 7: 6 6 tower river 'O.2000 0.2571
' late age.0 0.7040 NS 0.6228 NS .
- juveniles 6 6 i 8
5
' Fall <arly winter - 0.2036 river. bay 0.5017 NS age.0 juveniles 13
- Indices used correspond to those gisen sut T3hle 18.
6 Shown for each Spearman rank. correlation: correlatiun coefficient, . .
.i probability level (NS not significant, * - significant at p 5 0.05. ** . significant d p 5 0.01), and number of annual obse vations (sample size)
., s
' TAB 1.E 21. .%e expected and observed average abundance of female winter flounder spawners in the Niantic River determined from the'ob '
served size distribution of fish caught in the Niantic River from 1977 through 1989. Observed percentage - Actual percentage - Expected . Observed ; _ Fractior Age. mature" matureb ' Labundance abundance
- missing d 3 39- 8 ' 34,326 6,201 ' O.819 [
4 83 36 14,671 5.875 0.599 .' 5 98 - 92 6,270. 5,413 0,137' i 6 100 100 2,680 ) G ' 7 100 100 1,146 8 100 100 490 y 4,680 0 9 100. 100 209 1 10 100 100 89 , 11+ 100 100 65 4- t
- Detennined from the observed size distribution of fish caught in the Niantic River.
6
. Assumes that all fish fran the missing fraction not in the Niantic River were immature.
- Assumes a mean annual total instantaneous mortality rate of 0.85.
- d. Assumes that all fish of age 6 and older are mature and retum to the Niantic River for spawning. :
i: Winter Flounder Studies 53 is l_
1 females were missing from the spawning grounds in strength. Correlation coefficients were calculated be-the Niantic River, most likely because they were still tween various indices of larvac and juveniles and the ; immature and remained offshore, As only 39% of the abundance of female spawners at ages 3,4, and 5 6,201 age 3 females caught in the river were mature, (Table 22), 'the results of this analysis were not en. ; the true fraction of mature age-3 fish was probably couraging because the only significant correlations ' about 8%, Similar calculations for ages 4 and 5 found were negative, which may be partly a result of , ,
- yielded 36% and 92% of mature fish, respectively, the relatively small number of available observations.
Gibson (1989b) reported an age of 2.8 years at 50% The weakest of the negative correlations (not sig-maturity for Southern New England winter flounder, nificant) was found between the fully recruited age-5 This figure, however, may be an underestimate as spawners and the fall carly winter juveniles, which l' ' cvidence cxists for a 3 year cycle of oocyto maturation should have been one of the most reliable, If the l- in winter flounder (Dunn and Tyler 1969; Dunn 1970; negative correlations persist in future years, they l- Burton and Idler 1984). Thus, based on the biology could be interpreted as an indication of unknown i of the species, the age at 50% maturity should - processes operating after winter flounder become probably be least 3 years. Data for the Niantic River. 1 year old that result in fewer adults being recruited in female spawners suggested an age of 4 years or more spite of larger numbers of juveniles.' Meanwhile, at 50% maturity for this stock. none of these life-stages can presently be used as a reliable measure of year class strength. Assuming that catch indices were representative of annual relative abundances, the Niantic River winter The inability to c.orrelate abundance of carly life-flounder are not fully recruited until ages-5 or 6. stages with that of adult spawners forced the use of - Thus, age-3 fish should not be used as an index of -* adult fish to estimate annual recruitment. The cal-year class strength because only a very small and per- culation of the recruitment index was described in haps variable fraction of these fish are found on the detail in the Materials and Methods section. This spawning grounds each year. Similarly, correlations recruitment index plus the annual spawning stock in. between age 3 fish and younger groups may be un- dcx scaled to population size (Table 23) were used as reliable for identifying are early index of year class stock and recruitment data for'the SRR model - discussed below. 1 TAllt,li 22. Matrix of Spearman's rank order correlations amonp various winter flounder larval and remale spawner abundance indices._ MNPS intake Lower river t.ower river Fall early winter . Niantic River i larvae early age O late age O river-bay winter spring Index * (7+ mm) juveniles juvenile: juveniles age 1 juveniles Age 3 0.0727* 1.0000 -0.8000 0.6788 .0.5364 female 0.8317 NS <0.0001 *
- 0.2000 NS 0.0216
- 0.0890 NS h
spawriers 11 4 4- -11 -11 Age 4 0.0788 -d d 0.7538 0.1636 female 0.8217 NS 0.0118
- 0.6515 NS spawners 10 10 10 Age 5 0.3000 d d 0.3598 0.5500 female 0.4328 0.3415 NS 0.1250 NS spawners 9 9 9 liarly hfe history indices used correspond to those given on Table 18, 6
Determined by applying an age length key (NtJSCO 1989) to the length distribution of annual standardized female aNndances. c Shown for each Spearman rank correlation: correlation coefficient, probaNiity level (NS not significant, * - significant at p 5 0.05, " significant at p 5 0.01), and number of annual observations (sample site) d Not enough observations available (n 5 3). 54 Monitoring Studies,1989
~
TAlli.F. 23. Annual Wntic River winter flounder smck recruitment data based'on indices of egg production for the 1977 through the 1985 - year. classes with mean February wster temperature and deviations (Tm) from the mean, inden of female Index of female Mean February water Deviation from mean Feb. Year. class - spawners (P)* recruits (R)* temprature (*C) wster temperature (Tm) 1977 21,710 70,531 0.36 .l.82 1978 39,474 50,560 1.09 1.09 - 1979 29,450 41,890 1,48 0.70 -
~1980 23,344 33,912 .2.38 o.20-1981 76,093 33,351- 2.63; 0.45 1982 87,850 38,831 1.56 0.62 1983 59,528 4't,210 3.74 1.56 1984 27,596 29,494 4.02- 1.84 1985 36,283 25,709 2.36 0.18 Mean 44,592 40,832 2.18
- Scaled number of female spawners and recruits from expected egg production. Scaling factors used were 561.000 eggs pr female and a multipher of 30.864 to bring final numbers up to population aire.
Stock recruitment relationship (SRR) 7) is shown as the central broken line curve drawn near the solid line curve that - represents' the The slope (a) at the origin of the recruitment three parameter curve (adjusted SRR for the 1977 85 curve, also called " compensatory reserve of the stock" mean February temperature of 2,18'C; Table 23). (Goodyear 1977; Shepherd 1982; Savidge et al.1988) Finally, the two dashed-line curves included in the is the most important parameter in the SRR. same figure describe low recruitment in the warmest Shepherd (1982) suggested that if limited data are . year (1984; Treb = +1.84) and high recruitment in the available, it would be appropriate to simply estimate coldest year (1977;TF eb= 1.82). The method of ad-a as the slope of the line through the origin and the justing the two-parameter SRR for temperature effects F l data point giving the highest slope, Although this ~ (Lorda and Crecco 1987, American shad: Gibson
- j. method does not necessarily estimate a accurately, 1987 Rhode Island winter flounder) simply uses l Shepherd concluded that the chosen slope would be temperature as an explanatory variable to help reduce conservative. Such an estimate was used in NUSCO recruitment variability and obtain more reliable :
(1989) as the initial value of a in a nonlinear regres- parameter estimates for the SRR. Possible reasons sion procedure to fit Ricker's two-parameter model for the negative relationship between winter flounder ' -
- (Eq. 7) to the data. A similar method using data fmm recruitment and February temperatures were previous- !
this year (Table 23) gave a regression estimate of a ly discussed in NUSCO (1988a). - Although exact ! of 2.972 with a standard error of 0.877,or about 30% mechanisms are unknown, February coincides with l of the parameter value. A second fit to the data using spawning, egg incubation, and hatching. These the three parameter model with temperature effects processes, as well as larval- growth, are all (Eq. 8) provided a lower estimate for a of 2.M6, cor-temperature-dependent. In addition, the effect of tem-responding to a mean February temperature equal t perature on potential prey or predators (e.g., sand ' the 1977 85 mean, and a reduced standard error of shrimp) of larvae and newly metamorphosedjuveniles 0.599 or about 23% of the parameter value (Table cannot be dismissed and provides an additional sug-24). For tius model, the parameter c, corresponding gested means for control of population abundance. ! to the efrect of February temperature deviations (Treb) l from the mean, was negative ( 0.259) and significant
-(Table 24). The estimate of Ricker's parameter,
*Ihe three-parameter SRR explained 47% of the vari _ l ability associated with the recruitment index, which I which describes the annual rate of compensatory mor- was a decrease from the R2 of 71% reported last year '
tality as a function of the stock size, was 0.0000223. Both of these SRR's are shown in Figure 29 as fol- ; I lows: the unadjusted SRR (two parameter model; Eq. Winter Flounder Studies 55
}
TAH12 24. Parameters of the Ricker stock recruitment snodel fitted to Niantic river winter flounder data and some derived points of referen. cc. Model parameters and reference poinu . Model parameter Standard error t' a parameter (cornpensatory reserve) 2.646 0.599 4.41 " p parameter 2.228 10'8 4.56x10 8 ' 4.88 "
$ pararneter 0.2586 0.953 2.72
- liquilibrian stock (Py .
43.659 Fishing rate (F'go) for
- recruitment overfishing
- 0.868
- t. statistic for parameter estimate v 0 with d.f. e n.3 = 6 b
As defined by Sissenwine and Shepherd (1987). t 80-8 8 e 70 e 77, (0.3 6 0), . . . . . . . . . . . . , , , . ..,- 60-
, '/
, ' .~~. ,'
/
50- /
. 78 (1.09C) .,,'.,,,
,/ .~. -- --- -
. 83 (3.74C) 40- / ,/ ,., 79 (1.480) e82 (1,560) y l
l 30- ,/
/
f
/ e 80 (2.380)
.',s.s, (4.0 2.C.l . . . . . . .. . . . . . . .,,, , 81 (2.63C)
- 8 4...g
/ ,/ '
85 (2.360) ' ' .....* 20-a: a l l / , ',, ',. . . . l/ S 10- / ,', ' rt: ,,,- 1 b 10 20 30 40 50 60 70 80 90 100 1 FEMALE SPAWNERS IN THOUSANDS l l Fig. 29. The Ricker SRRs for Niantic River winter flounder with February mean temperature (*C) shown for each year < lass l (see text for explanation of the four curves plotted). 1 I i l l l ! 56 Monitoring Studies,1989 l l
I (NUSCO 1989). This was due to the latest recruit- and, therefore, should have provided a values
. ment index calculated (1985 year class), which was corresponding to a compensatory reserve diminished less than expected given the parental stock size and by the prevalent exploitation rate. Goodyear (1977) prevailing February water temperature in 1985. discussed the concept of compensatory reserve in flowever, this recruitment estimate was only pre- fishing stocks and the effect of exploitation on the liminary treause its value relied on a single age- shape of the reproduction curve when the recruitment group (age-4) to which annual estimates of survival, index is based on the exploited stock (Goodyear 1977:
maturity, and fecundity were applied to numbers ex. Fig.1), This implied that as fishing rates increase, ! pected in future years. For incompletely recruited age. the estimates of recruitment will decrease as will the ; classes, this procedure may have resulted in con. estimarcs of a (i.e., the " remaining" compensatory i siderable error For older, fully recruited year classes, reserve). During 1990, the possibility of using indir-calculations were more reliable because the index was cct methods to estimate the true a parameter (i.e., for based on the observed abundance of spawners during the virgin stock when F=0) will_ be investigated. several years. Thus, data from future surveys should Methods not depending on direct estimates of recruit. result in improved recruitment estimates for the most - ment are advantageous because they avoid biases recent year classes with more reliance placed on ob. caused by changing fishing rates and provide indepen-served catches and less on projections of future egg dent means of validating SRR based estimates, production. Biological reference points of interest associated with the SRR include the theoretical equilibrium size Winter flounder population dynamics model Eq.10) and the fishing rate for of the stock
" recruitment overf (P,$s;hing"(F go: Eq.12). Pyat aver- Afodelinput data and nm modes -
age fishing rates prior to 1985 was calculated as The input data used to initialize the population - 43,659 female spawners (Table 24), which compared model for the Niantic River winter flounder stock to a mean stock size of 44,592 spawners from the included basic life table parameters for the adult'
- 1977 85 data (Table 23). The limiting tishing rate population (e.g., number of age classes and age. _ [
Fgo was derived from the a estimate as F=0.868. specific rates of maturation, natural mortality and This value is still well above current fishing rates, fishing); an initial spawning stock size; the mean believed to be about 0.60-0.65 (P. Howell, CT DEP, fecundity (assumed constant); the three-parameter es- ' Waterford, C1', pers, comm). Although all these cal- timates of the SRR;: statistics from actual water culations assume a stable " average" exploitation rate temperature data in February during 1977 85 (e.g., corresponding to F=0.50 during the period of 1977 mean, standard deviation, and temperature range); and 85, it appears now that this assumption was not met simulation parameters specific for each model run, (especially in more recent years) because fishing mor- such as number of time-steps or years for the popula-tality has been steadily rising since 1978 (Smith et tion projection, number of Monte Carlo replications al.1989), desired, whether the effect of larval entrainment at MNPS was to be simulated, and whether initial In an update to his previous work, Gibson (1989c) fishing rates were to be changed during the simulation provided SRR a values estimated for several other (Table 25). Model runs were either deterministic or j Southern New England winter flounder stocks that stochastic, depending on the input simulation ranged from 2.22 to 2.59. These estimates were not parameters. The model output for deterministic runs ' significantly different from the a values obtained in was a single projection of spawning stock ' sizes (or this study. The estimate for a of 2.M6 was very time-series) over the number of years specified in the likely an underestimate of the true slope at the origin input data.' In addition, annual February temperatures for the Niantic River winter flounder as it occurred were held constant and equal to the input mean value ' between the slopes corresponding to the 1977 year- during the entire simulation. Alternatively, stochas-class and the strong, but less dominant,1980 tic runs generated a specified number of time-series ' ' year-class (Fig. 29). -In addition, the present method replicates (50 in this study) and annual February of calculating annual recruitment already incorporated temperatures were random variates from a truncated ! the effect of exploitation on fish of age-3 and older normal distribution with the range, mean and standard Winter Flounder Studies 57
=
1 w e - I
TABLE 25. Data, rates, and other inputs used with the Niantic River winter nounder pgulation dynamics sirnulation model Modelin;as Value used or available e Number of age <lassses in population 15 Earliest age at which all females are mature 6 Matute fraction of age-I females O Mature fraction of age 2 females 0 , Mature fraction of age-3 females 0.08 Mature fraction of age-4 females 0.36 i Mature fraction of age 5 females 0.92 Age after which mortahty remains constant . 3 Instantaneous mortality rates M and F at age-I 0.50 0.00 Instantaneous mortahey rates M and F at age-2 0.40 0.15 Instantaneous mortahty rates M and F at age 3+ 0.35 . 0.50 . Initial female spawning stock size 50,000 Mean f:condity of the stock (eggs / female spawner) 561,000
- fnwn Ricker's three. parameter SRR 2.6455 11 from Ricker's three parameter SRR - 2.2283x10 8 9 inun Ricker's three parameter SRR 0.2586 Mean February (1977 85) water temperature ('C) 2.18 standard deviation 1.20 !
minumum temperature 0.36 maximum temperature 4.02 Number of spawning cycles (years) to simulate 40' Number of simulation replicates per run 16 Fraction of age-O group entrained at MNPS (i.e., impact) 0.0 05
'i 100 spawnins cycles used in stochastie simulations, b
Number of replicates for a deterministic sirnulation is 1.
- Simuhting a non impacted stock; otherwise the conditional mortahty due to entrainment is used.
deviation specified as input. A second form of ran- SRR (Table 24). Similarly, the simulated recruit-dom variability (the " noise" component nii n Eq.18) ment also converged to the same number of potential was also present in the time-series generated by Spawners, thus indicating a stock at equilibrium. stochastic runs. The amount of variability needed for This exercise simply verified the correctness of the this random input was determined during the calibra- computer program code and the validity of Equation tion runs described below. 18 (see Materials and Methods section) to incorporate the behavior underlying the SRR. Modelcalibration A second set of model runs was conducted in the The model was first rtm in deterministic mode over stochastic mode to determine the amount of random' 40 years to generate a projection of the winter floun. noise required to provide realistic " uncertainty" about der stock under initial conditions and constant the input value of (1. This was accomplished by trial-February water temperature equal to the 1977-85 and-crror adjustments of the value of c, which con-average. Under these conditions the stock converged trolled the variability of the random normal deviates - rapidly from any arbitrary initial size to the n, in Equation 18. The calibration process required equilibrium size of 43,659 spawners predicted by the about 20 model runs with 80-year time-series, each 58 Monitoring Studies,1989 l
replicated 50 times. An acceptable final value for o single age-class of winter flounder as an index of ; of 0.10 resulted in the following range of " effective" stock and recruitment abundance, an assumption of a values: constant mean fecundity for winter flounder (this may . 1.4 s a s 4.1 have climinated some " noise" in 'the model calcula- ; This range was similar to the 95% Cl derived for a tions of age-1 fish), and because abundance estimates ' from the data (standard error =0.599; Table 24), which were based on experimental catches within sampling was: programs specifically designed to provide stock and ' l.2 s (n=2.645) s 4.1 recruitment data. Additionally, substantial data were t available on age composition of the stock and this in-The above calibration runs were also used to verify formation constituted the basis for the estimates of that the two types of random deviates generated by the potential recruitment. model, n, and WT, (Eq.18), had mean and variance consistent with the input parameters (Table 25). The temperature effect (second exponential term in the Deterministic stock aSScSSment SRR, Eq. 8) resulting from the random water temper-atures was also examined. This effect was equivalent The winter flounder model was used to investigate to scaling the initial value of a by factors ranging the response of the sp wning stock to increasing ex. from 0.644 (for the warmest temperature) to 1.556 ploitation rates by simply projecting the initial stock - (for the coldest). No calibration of this effect was size under different fishing rates, from an initial value needed because the variance associated with the ran- of F=0.50 to higher values of 0.55,0.60, ard 0.65, dom temperatures was derived from the actual 1977 This range of F values was thought to approximately 85 temperature data and given to the model as input describe the exploitation rates for local winter floun-(Table 25), der since 1980, when Connecticut commercial catches began to rise sharply (Smith et al.1989). Further simulation studies were carried out to verify that, given the above levels of stochastic variation, ' Because the purpose of these simulations was to es-the model generated time-series of stock, recruitmeni, timate the equilibrium or sustainable stock size for and temperature data were usable to re-estimate the each of the above-mentioned fishing rates, the model three parameters of the SRR by means of nonlinear was run in deterministic mode (i.e., a single time-regression methods. This type of simulation exercise series per run with no added variability). In each case was suggested by Christensen and Goodyear (1988) an initial stock size of 45,000 female spawners (about
'with the stated purpose of validating the reliability of the actual average during 1977-85) converged to a con- ,
the estimation methods used to obtain values of a - stant smaller size in about 20 years. The equilibrium ' from actual stock and recruitment data. This exercise stock sizes of female spawners for each of the three ex-should t'.lso confirm the capability of the model to ploitation rates were: 39,595 at F=0,55; 33,491-at simulate stock dynamics consistent with Ricker's F=0.60; and 27,575 at F=0.65. This deterministic form of recruitment. The SRR was repeatedly fitted simulation method (unlike Eq.11) incorporated the l to the random time-series generated by the model to effect of a multi age stock and exactly reproduced the l obtain estimates of the three parameters, which were harvesting of each year class during 12 consecutive generally similar to those obtained from actual data years (from ages-2 to 14), Similar results obtained (Table 24). This was especially true in the case of through stochastic simulation with these same three the p and & parameters, which were consistently es- fishing rates are later summarized in Figure 33 below. - timated as precisely or better than from the actual l data. The a parameter was correctly estimated (within the 95% Cl derived from the data) in about 35 Stochastic simulation of the Niantic River of the 50 model runs conducted and somewhat less winterflounder Stock precisely (off by as much as a factor of 2) in the other runs. In no case was the estimate of a biased to the Before applying the population model to assess the extent reported by Christensen and Goodyear (1988) long-term effect of larval entrainment'under three-unit in their study involving the Hudson River striped - operation regime at MNFS, it was necessary to create bass (Morone saratilis). Reasons for this disparity in a baseline or " reference" stock under two-unit results most likely included the use of more than a operation. This baseline consisted of 50 replicates of Winter Flounder Studies 59
a stochastic winter flounder stock series under the (0.55). The variability of the series appeared realistic conditions prior to 1986. Because the average (CV=38%), but the largest stock predicted was only exploitation rate during the period of 1977-85 was not about 49,000 Gsh, well below the record estimated precisely known, a value of F=0.50 was initially stock sizes (over 80,000 fish) of 1981 and 1982 chosen as a best estimate, even though the actual (Table 6) resulting from the dominant 1977 year-value was probably somewhat higher by 1985. This class. Averaging the 50 replicates of the baseline was a reasonable choice because the last two or three showed that the mean stock size had small fluctua. year classes in the data were still partially harvested tions from year to year and relatively narrow 95% and, thus, not fully affected by the higher F values at confidence intervals (Fig. 31). The 80-year geometric the end of this period. Nevertheless,in an attempt to mean of the series was 39,500 (range of about 27,000 provide a more conservative reference for the assess- to 60,000). As expected, the maxima and minima ments, the final baseline series were generated with showed much larger variation. The maxima often constant F (0.55) and an arbitrary initial stock size of reached 60,000 fish, larger that the maximum of the 50,000 female spawners. The series length was 100 single series shown in the previous figure, but still years, but the first 20 years (when the stock below the above mentioned record stock sizes. This converged to its equilibrium level) were subsequently apparent tendency of the simulation at F=0.55 for discarded to insure a baseline that would represent a producing smaller dominant year-classes suggested winter flounder stock fluctuating about its sustainable that fishing rates in the recent past were much less size at F=0.55, than 0.55. The simulated age composition of the baseline stock and the' annual catch at F=0,55 are The 80-year mean stock size (39,643 fish) of one of shown in Table 26 for the first three replicates of the the 50 replicates of the baseline series (Fig. 30) was last year of the time-series (Fig. 31). Also included
~
almost identical to the deterministic equilibrium stock in the table is the actual age composition of the size of 39,595 fish given previously for the same F Niantic River winter flounder stock as estimated from 50-m O k y 45-o 6 Z 40- y --- A - --- -- ,- m m w z 35-g n-m 30-d Maximum = 49,223
- i y Mean-(dashed line) = 39,643 25 Minimum = 29,842 0 5 10 15 20 25 30 55 40 45 5O 55 60 l TIME (YEARS) l l
Fig. 30. Stochastic simulation of the Niantic River female winter flounder spawning stock with a unstant exploitation rate corresponding to F=0.55 and variation in the a parameter due to tuth water temperature and random i ,ise. l 1 60 Monitoring Studies,1989
s 65- ! m Maxima ' O + g
- o o l
Ln O o D o o o .o oo *o o oo 55 o o o oo oo.o o c oo ,o o, 00 o oo- o .o oo o o oo , o,c o e o- o,og oo o m g 45- Mean and 95x Cl -i O. h ' ' M ld '35- oooo i
,c -o oo ,oo o o o o o o o o*o co c .o oo ooo o oo o' - o oo oooooo oo *oo oo ,o( o; s
- k. ,
M,inimo
* *o ;
25 a 0- 5 10 15 20 25 30- 35 40 45- .50 55 60 i 1 TIME (YEARS) g
.L Fig. 31, llaseline stochastic simulation (mean of 50 Monte Carlo replicates) of the Niantic River winter flounder stock - y with constant fishing rate (F=0.55). This baseline or reference series simulated the stock dynamics prior to MNPS Unit 3 operation (l.c., larval entrainment at 1977 86 levels), .-
I ( P TADl.E 26. Age composition of the 1981 Niantic River winter flounder spawning stock as derived from actual survey data, and simulated l age compositions of the stock and annual catch at F=0.55.
~
f Simulated age composition * - ! ! 1981 Niantic River % of total stock- % of total c. rh3 l Age stock (% of total) Rep.1 Rep.2 . Rep.3 : Rep.I Rep. 2 - ' Rep.3 2 - - - - 26.8 38.8 40.1 3 7.8 17.9 12.4 - 10.4 44.6 33.8 29.5 l 4 19.9 33.8 19.9 22.8 18.6 12.0 14.4
- l. 5 36.8 26.9 35.4 - 42.5 5.8 8.4 10.5-1- '6 25.6 12.4 20.0 15.6 2.5 - 4.4 3.5 l 7 6.6 4.5 8.5 4.5 0.9 1.9 .l.0 8+ 3.3 4.5 3.8 4.2 0.8 0.7 - 1.0 j
- i i
- Detennined from replicates I,2, and 3 of the last year in the tuseline time-series (Fig. 31).
l i adult population survey data in 1981. That year was annual spawning stock simulated was dominated by f chosen because the survey had one of the largest and fish of ages-4 through 6. Although there was a great ; most complete sets of length and rtre data available deal of variance from year to year, the simulated age ; and was assumed to be more reliable than other years. compositions were not unlike the age structure j The breakdown by age-classes showed that the typical estimated from the data in 1981; this was especially j t Winter Flounder Studies 61 l
i i true for replicate numler 2. Examination of the age included 2% in Stage 1,27% in Stage 2,60% in composition of the simulated annual catches showed Stage 3, and 11% in Stage 4 of development, that over 70% of the total consisted of very young fish (ages 2 and 3). Catche.4 dominated by very young fish are typical of heavily exploited stocks Efect ofentraintnent on the year class (Ricker 1975).- Annual entrainment estimates were compared to in. MNPS impact assessment dices of abundance for ages 0 and 1 juvenile winter flounder (Table 28). Although none of these post. Estimates oflarval entrainment at MNPS entrainment life stages was significantly correlated with total larval entrainment, sample sizes of avail- i Yearly totals of winter flounder larvac entrained able data were relatively small(713). Nevertheless. ' through the cooling water system at MNPS were the correlation coefficients were all positive (i.e., no related to larval densities in Niantic Ilay and plant ' adverse effect),except for the index of age-1 fish. The operations. Generally,larvac were found at MNPS reliability of the age 1 abundance index as a true from late February through June, with most entraint measure of year class strength is questionable, as dis-ment occurring from mid April through May The cussed previously in this report. The negative cor-median larval entrainment density of 165.7 per 500 relation between the apparent survival of 7+ mm lat. m3in 1989 was nearly twice the value of 86.1 for vac through age l and total entrainment could be in-1988 and was the fifth largest since 1976 (Table 27). terpreted as an adverse effect of entrainment on Despite the high median, the estimated number year-class strength. However, that negative correla-entrained (131.3 million) was not unlike the totals for tion was not significant and, furthermore, the group 1986-88 (109.4-138.0 million) because of the lesser of age 1 fish did not appear correlated with adult < amount of cooling water used by MNPS in 1989. As spawners (Table 22). In general, negative correlations in previous years, larvae in Stage 3 of development between annual entrainment and survival of early life predominated in entrainment collections. For 1989, history stages do not necessarily imply an entrain-the percentage of each developmental stage entrained ment impact unless positive correlations between was 2% for Stage 1,30% for Stage 2,61% for Stage those early life history slages and mature female fish 3, and 7% for Stage 4. This was similar to the can also be demonstrated. proportions found overall during 1983 88, which 3 TAHl.E 27. Annual median densities (number per 500 m ) or winter flounder larvae in entrainment samples during their season of occurren-ce, total entrainment estimates with approximate 95% confidence interval, and the number of 500 m 3units of seawater entrained during , each season at MNPS from 1976 through 1989. Total - Numberof 500 Year Median 95% CI 95% CI 3 3 estimate (XIO*) m units (X10 ) 1976 158.0 114 1R8 94.8 68 113 599.9 1977 64.1 >3 87 29.3 2440 457.8 1978 86.6 65 106 57.8 43 70 666.7 1979 90.3 70 108 36.7 28 44 406.8 1980 201.5 164 235 40.6 114 164 697.6 1981 139.2 99 183 47.4 34 62 340.7 - . 1982 183.5 148 215 126.6 102 148 690.0 1983 244.4 158 315 171.7 111 221 704.6 1984 185.5 108 226 90.4 52 110 487.0 1985 107.1 79 153 66.0 49 94 616.1 1986 94.0 73 120 109.4 85 139 1,163.6 1547 88.9 65 109 126.2 93 154 1,419.5 1988 56.1 59-136 138,0 1,603.4 95 218 1989 165.7 129 228 131.3 102 180 792.2 62 Monitoring Studies,1989
1 Altt.E 2s. Mattia of ?,pestman's ranborder correlations betw.wn the m.muel estimates of larval winter flounder entratnment at MNPf. and sevetal pnst. entrain neut eady life history steget. L4=er river tower rivet Fall early minter Niantic River Apparent larval early age 0 late age O river bay winter. spring survival Indca' juveniles juveniles juveniles age-1 juveniles rate Annual 0.50nn* 0.5714 0.44s4 0.4725 0.5275 estiinate of 0.2532 NS 0.1802 NS 0.1243 NS 0.1030 NS 0.tNO NS entrainment 7 7 13 13 13
- 1rnhces aied merespond to thm given m Table 18, encept for the a; parent survivat rate, uhich is the age-1 indes divided t,y the inden of 7 mm aclarger tagne in Niantic lisy.
6 Shown fu each Spearneart ratibcorrelation: correlation coefficient, probability level (NS not significant, * . significant at p 5 0,05, " significant at p 5 0.01), and numhet of annual observations (sample sire) Probabilistic risk assessment (PRA) oflan'al impacted serics was the average of 50 Monte Carlo enfrainment trials or replications. Although the bascime in Fig-ure 32 appeared more variable than in Figure 31, this The long term effect of larval entrainment at was only an artifact of the smaller scale of the vertical MNPS (three unit operation) on the Niantic River axis in the former The response to the first impact winter flounder stock was investigated by simulating appeared in the series with a lag corresponding to the the addition of entrainment losses to the baseline time of maturation, The stock size fell to its lowest stock descrihed previously (Fig. 31). The entrain- level with different lags: 10 years in the case of 5 and ment rates chosen for this simulation were equivalent 10% entrainment, and 15 years in the case of 15% to hypothetical year class reductions of 5,10, and entrainment. The retum time to pre impact size was 15% These rates were also used in NUSCO (1989) practically the same for the three rates of entrainment, and justified as corresponding to " probable", *conser. and this resulted in a much steeper slope during the vative", and extreme" entrainment rates due to three- recovery for the series corresponding to the 15% unit operation after 1986, The simulation strategy entrainment rate. Expected stock sizes on the 50th was to start the impact of Unit 3 in the 10th year of year were approximately 40,700,38,400,36,000, and the time series, sustain entrainment at the chosen rate 33.500 female spawners for 0,5,10, and 15% levels ~ during the next 40 years, stop the impact in the 50th of entrainment,respectively The corresponding long-year, and com.nue the simulation without Unit 3 term (40 years) stock reductions predicted were 5,5%, entrainment for another 30 years. The purpose of this 11.4%, and 17.6% These results were compared to ldmulation scheme was to gain insight into the stock deterministic estimates obtained from model EREl ' i -- dynamics following the start of the impact, during an (Eq.18) of Savidge et al. (1988) after adjusting the cz extended period of sustained impact (long enough to parameter for F=0,55 (Table 29), A good agreement bring the stock to a lower equilibrium size), and was found between stochastic and deterministic esti; during the recovery period following the climination mates and, in both cases, results were similar to esti-of the impact. The latter period was of particular in- mated relative stock reductions reported in NUSCO terest because it provides a measure of the stock (1989). resiliency in terms of time required to return to pre- _
' impact condition. _Instead of calculating confidence limits for the stochastic estimates of stock reduction, their statisti-Results of the simulations conducted for each cal interpretation was based on probabilistic risk as-entraiement rate were summarized in Figure 32 by sessment (PRA) methodology, Probabilities of postu-comparing the three impacted stock time-series to the lated stock reductions (Table 30) were calculated in-baseline series (non impacted stock) from Figure 31. this study using the sampic distribution function As in the case of the baseline series, each of the :.hree (Stuart and Ord 1987) of the 50 random stock sizes in .
Winter Flounder Studies - 63
45 No Period of 3- unit Recovery period - l m Unit 3 entroinment 9 ' impact b o 4o. oENT %, ; o , b 5x ENT -! 2 - a m 10x ENT l g 35-Z 15x ENT l k0. !
+
M 30-4 '
~
25-0 10 20 30 40 50 60 70' 80 TIME (YEARS) $ i' Fig. 32. Comparison of the Niantic River winter 11ounder stock baseline (Fig. 31) to stock projections with three different entrainment rates sustained over 40 years (10th through 49th year). Each series scpresents the mean of 50 Monte Carlo -
- teplicates with fishing tale held constant at F.O.55. >
TAlttti 29. Niantic river winter floimder spawning stock sire reductions predicted for three rates of entrainment by two different methods, Stochastic baseline Reductums relative to mm impacted stock siae: Rate of entrainment stock sin in the 50th year' - Methmi Ib Method 2* - o 40,724 . . 5% 38,458 5.57 % 5.81% ~ 10% 36.065 11.44 % 11.94 %. 'i 15 % 33.533 17.66 % 18,42% ' Refers to the time series in Figure 32.
- Stochastic simulation (see Figu e 32% Non impacted stock slie is the size in the 50th year of the beieline (i.e.,40.724 fish).
' Savidge et al. (1988) model EREl (see Eq.17), Non impacted stock sie is the detenninistic equilibrium size at F=0.55 (i e. 39.595 fish). l the 50th year of the time series (Fig. 32). Prob- than its 80-year average simply due to " natural" vari- l abilities in the first row of Table 30 (non impacted ability. The interpretation of the table is straight- , stock) illustrate the background variability of the forward; for example, the chance that the stock reduc- t baseline series. For instance, there is an inherent tion will be less than 5% when the entrainment rate 12% chance that the stock size will be 510% smaller is 5% is approximately 54% and this probability ; i Monitoring Studies,'1989 64
)
b t TAif tI 30 prot.4ldlatic risk assessmen rPRA) of tire reductions in the Niantic River winter flounder stock after 40 years of simulated [ year.slass huses tesutting from three different vaies of luvat entrainment and a constant esploitation rate correspondmg to F=0.S$. probatuhties of postulated stock sire reductkms were esti nated from $0 Wnte Carlo trials. , Year. class Probabuity of postulated reductions relative to non impacted simk' kistducto ? entrainment <$% $.10% 10 15% 15 20% 20-2$% 2530% > 30% None 0.71 0.12 0.08 0.05 0.03 0.01 0~ f
$% 0.$ 4 0.16 0.12 0.09 0.05 0.04 0 ,
10% 0.33 0.19 0.16 0.12 0.10 0.07 0.03 ? 15 % 0.08 o 24 0.2 t 0.18 0.14 0.10 0.05
)
' Non impacted stod sire was 40,724 female spawners (i.e., the mean sire in the $0th year or the simhastic bascime series).
tecomes 33% and 8% when entrainment rates increase last result was expected because entrainment impacts to 10 and 15%, respectively. At the other extreme, each year class only once, whereas harvesting by the the probability of reductions greater than 30% is rero fishery continues for as long as the year class remains . for 5% entrainment and only 3% and 5% for entrain- vulnerable to fishing (McFadden 1977). ment rates of 10 and 15%, respectively. The prob-ability of any other postulated reduction can be ob. Finally, the long term effect of entrainment at Unit tained directly from the table in a similar manner, 3 in combination with rising fishing rates was inves-Probabilities along tows also may be added (each row tigated using PRA methodology. The impact of both adds up to 1.00) to find the aggregated probability of, these effects on the Niantic River winter flounder for example, reductions greater than 10%, which stock is summarized on Table 31, which should be would be given by the sum of the last five proba- hterpreted similarly to Table 30. . The probabilities bilities in each row of the table, shown in the rows corresponding to F=0.55 come from Table 30 - Probabilities of stock reductions at The different effects resulting imm increasing either higher fishing rates indicated that entrainment effects entrainment or fishing rates were also investigated were magnified by fishing (i.e., larger stock reduc-through stochastic simulation. The fishing rates sim- tions became more likely' as fishing pressure in-ulated of F=0.60 and 0.65 represented increased con- creased). For instance, for a 10% entrainment rate, ditional mortalities of about 5 and 10% over the the probabilities of having stock reductions greater baseline fishing rate of F=0,55 (Fig. 33). These con- than 10% were 0.48 at F=0.55,0.54 at F=0.60, and - ditional mortality rates were equivalent to the first 0.56 at F=0.65. - Although these increases were not - two entrainment rates simulated in Figure 32 (i.e., in dramatic, the postulated stock reductions were calcu.
- both cases the probability of survival is decreased by lated from increasingly smaller non impacted stock factors of 0.95 and 0.90). The predicted stock sizes sizes (see footnote in Table 31). If there is a critical on the 50th year were about 40,700, 34,600, and biomass of female spawners below which the stock 28,500 female spawners for fishing rates of 0.55 - becomes unstable, then the continued rise of fishing 0.60, and 0.65, respectively. No lag was seen as a rates above the current levels of 0.60-0.65 should be a result of increasing fishing rates in the 10th year, or cause for concern. This simulation study has shown '
in the stock recovery once fishing returned to baseline that F=0.65 would result in a 35% reduction in stock levels of F=0.55. It was also clear (Figures 32 and size from the 1977 85 mean of 45,000 female 33 have identical scales) that the stock reductions spawners, even without entrainment. - caused by increased fishing were greater than corresponding reductions resulting from identical con ditional mortality increases due to entrainment. This Winter Flounder Studies ' 65
i i l i l 45' i m - F=0.55 Period of increased F F=0.55 40-
$ F=0.55 ,
E , m > g 35- l h F= 0.60 ; 30- f F=0.65 25- i b 10 20 30 40 50 60 70 80 ; TIME (YEARS) { Fig. 33. Compsison of the Niantic River winter flounder stock baseline (Fig. 31) to 6tock propctions at increased fishing rates sustainert over 40 years. Each series represents the mean of $0 Monte Carlo replicates with no larval entrainment at y MNpS.
- I i
TAllLil 31. Prohobilistic risk assessnwns (PRA) of sin reductions in the Nientic River winter nounder stock after 40 years of simulated ; year. class losses resuhing from three rates of larvel entrainment at three different fishing rates. Probabilities of postulated stuck aim .
~
t reductions were estimated from 50 Monic Carlo trials. j Yur. class Probability of postulated reductions relative to non-impacted stook' loss due to Fishing rete l entrainment O') <5% 5 10 % 10 20% 2040% 30-40% > 40% ! 0.55 0.54 0.16 0.21 0.09 0 0 5% 0.60 0.50 0.14 0.20 0.16 0 0 0.65 0,44 0.14 0.26 0.16 0 0 0.55 0.33 0.19 0.28 0.17 0.03 0 t 105 0.60 0.28 0.18 0.30 0.20 0.04 0 , 0.65 0.18 0.26 0.28 0.26 0.02 - 0 0.55 0.08 0.24 0.39 0.24 0.05 0 15 % 0.60 0.08. 0,16 0.30 0.28. 0.16 0.02 0.65 0,04 0.14 0.28 0.38 0.14 0.02
- Non impacted stock sin see the snean sin in the 50th year of the stochastic basehne series for each fishing rate: 40,700 for F=0.55; 34.600 for F=0.fo, and 28.500 for F=065.
t 66 Monitoring Studies,1989 6
F Conclusions and 1989. Over the 7 year period, except for 1988 j when mortality appeared to have been low, only + Niantic River spawning sinck sundance currently small differcnces were seen in mortahty of young in ! remains low as relatively poor yes,r claw.a produced the Niar.lic River. As the 1988 year-class was appar- ! during the mid-1980s entered the population. Based ently the largest one produced since 1983, this sug- , on observations of spawners in the river, it was con- gested that processes occurring after larval metamor- ! ciuded that most females recruit to the spawning phosis could also le important in determining winter ~ j population at ages 5 or 6. Greater than optimal adult flounder year class strength. A suggested regulatory l stock sizes and generally warmer than average winter mechanism was predation by sand shrimp on ' water temperatures occurred during most of the 1980s, metamorphosing young in early spring. > In addition, the rates of fishing increased dramatically , during the decade. As more older and larger females Unfortunately, no linkages were found among . comprised the spawning stock, however, individual various life history stages beyond those of femalc , mean fecundity has increased and egg production spawner, egg, and Stage 1 larvac. Sampling vari-equaled or exceeded estimates from previous years that ability, fish tchavior, and limited data for compari- , had more numerous but smaller female spawners. As sons (because of the 5 to 6 year recruitment period for good correspondence was found among CpUE, annual females) have limited the ability to identify an early : standardized catches, and Jolly abundance estimates, it life history stage as a reliable index of year class was possible to estimate absolute female spawning strength. Thus, recruitment indices needed for the stock size and egg production. From 1977 through SRR were limited to estimates of adult recruits and - 1985, the annual number of spawning females ranged calculations of their lifetime egg production. ; from 20 to 85 thousand and egg production from 12 ! to 49 billion. These estimates were used as parental Although new estimates of the SRR parameters > stock in the Ricker SRR, which was developed for were not significantly different from previously re- 7 impact assessment. ported estimates (NUSCO 1989), the all imponant n ; parameter was smaller,2.646, in comparison to a . Based on observations of adult spawners and the value of 2.8M reported in NUSCO (1989). In addi-abundance and distribution of Stage 1 larvac, peak tion to the low precision of the latest recruitment esti- - spawning occurred in mid February and took place mate (1985 year class), the decline in a can be attrib-primarily in the Niantic River. Annual abundance uted to greater exploitation of this year class than of irxtices for Stage I larvae at the Niantic River stations preceding year classes (1977 84). This apparent
\ vere similar, which indicated a homogeneous distrib- decline of a simply reflected the decline in adult ution of yolk sac larvae within the river. During recruitment due to higher fishing rates, rather than a development from Stage I to 2, similar annual rates change in the stock 4ccruitment relationship :
of larval loss, attributed to both mortality and (Goodyear 1977). Because of the trend of increasing I flushing, were found. Based on the estimated dates of exploitation rates since 1980 (Smith et al.1989), the l peak abundance, most flushing from the river to the estimates of a during the next 2 or 3 years are also bay occurred during Stage 2 of larval development. In expected to be smaller. Niantic Bay, growth and development were positively . . correlated with water temperature, but in the Niantic The modeling approach to stock and impact River growth appeared to have been density. assessment presented in this report resolved some ; dependent, possibly due to prey availability. Larval problems resulting from the application of stock-mortality also appeared to have been density depen- recruitment theory, originally developed for semel; + dent at the time of first feeding, supporting the "criti- parous fish, to the multiple age winter flounder 'r
- cal period" concept, spawners. In addition, the winter flounder model ex- '
plicitly incorporated the uncertainty associated with - Considerable differences existed between Niantic the estimation of the critical a parameter and, thus, } River and Bay in the growth and survival of demersal provided more realistic assessments of the long term young from late May through September Growth of effect of year class losses resulting from either larval post larval young varied among years and was likely entrainment at MNpS, higher fishing rates, or a density-dependent. Due to apparently high mortality, combination of both. Despite recent criticism of , very few young were produced in Niantic Bay in 1988 SRR based models (Christensen and Goodyear 1988), Winter Flounder Studies 67 t
.c .,
n
the simulations carried cat with the NUSCO winter and the Jolly estimates. flounder model indicate:I that the estimate 3 of adult ' reauitment derived from the Niantic River popu!ation 3. The annual standardized catched far 1984-87 were data pmelded reasonable model parameters. As Chris- found to represent about 2.8 to 4.5% of each cone-tensen and Goodyear (1988) suggeved, the use of sponding annual population estimate. Assuming a reliable age-structure information, which was avail. similar mean ratio for all survey years, a multipher of able for the Niantic River winter flounder stock, 30.864 was used to scale relative numbers of females probably accounted for the more favorable results and eggs into absolute numbers for assessment pur-reported in this study, poses. Use of this scaling factor with annual sex, ' age, and size composition data enabled the estimation Results of the new probabilistic risk assessments of female parental stock sir.c for use in models of the conducted this year confirmed NUSCO's (1989) con- stock recruitment relationship (SRR). clusions predicting further decline of the winter flounder stock over the next few years. Although 4. Spawning in the Niantic River takes place from predicted stock reductions caused by larval entrain. January through late March or early April. As spawn-ment under three unit operation since 1986 were ing activity was apparently positively correlated with generally about 5 to 10%, degending on the simulated water temperature, egg deposition was completed car. entrainment rates, these reductions will apply to lier in recent years that had warmer winters, increasingly smaller spawning stocks unless the appar. ent trend of higher fishing rates sinec 1980 is soon 5. Mature female fish made up between a third and a reversed. Present fishing rates of F=0.65 are already half of the annual catches of winter flounder in the high enough to weaken the effect of dominant year. Niantic River during the spawning period. Absolute classes that in the recent past sustained the stock numbers ranged from about 20 to 85 thousand during when exploitation rates were moderate. Therefore, 1977 88; the largest numbers of spawners were stock recoveries will become weaker and increasingly present during the early 1980s. Total egg production infreciuent if fishing pressure on the stock increases (12-49 billion) also peaked then, but mean fecundity above present levels. has recently increased as older and larger females made up a larger proportion of the spawners than in Finally, the probability of stock collapse was still previous years, too small to be predicted by the population model , under present conditions. The largest stock reduction 6, ne pattern of abundance for larval winter flounder predicted was 55%, which occurred only once in the in 1989 at three stations in the Niantic River, a sta-50 replicate series and corresponded to both the tion in mid-Niantic Bay, and at the discharges of highest entrainment rate (15%) and sustained fishing MNPS (entrainment sampling) was similar to rate (F=0.65) simulated. previous years of sampling. Abundance of larvac in the river during 1989 was the second highest observed Summary during the past 7 years, following that for 1988, in the river, abundance peaked in early March and then
- 1. The median trawl CPUE of winter flounder larger rapidly declined, but in the bay an increase occurred than 15 cm in the Niantic River during the 1989 from mid. March to mid April. Because these changes spawning season was 12.2, the second smallest index coincided, they suggested that many larvac were of the 14 year series. Because of poor year-classes flushed from the river to the bay.
produced in the mid 1980s, the spawning population since 1985 has primarily teen comprised of fish older 7. The annual abundance of yolk sac larvac (Stage 1) andlarger each successive year, in the river was positively cortclated to the reproduc-tive capacity of the spawning stock and indicated that
- 2. Estimates of absolute abumiance based on the Jci- egg hatching rates were consistent from year to year.
ly model for 1984 88 ranged between 48 and 77 he temporal occurrence of each developmental stage thousand fish. Sampling intensities were relatively in the river and bay showed that a majority of the low (0.03 0.08), indicating potentially inaccurate spawning occurred in the river and that flushing of ! abundance estimates, llowever, a good correspon- larvae from the river to the bay took place primarily l dence was found between annual median trawl CPUE during Stage 2 of development. The time of peak l l 68 Monitoring Studies,1989 l l
l abundance for Stages 3 and 4 larvac was generally and those for adults. , similar between the river and bay over the last 7 years. 12. The 6.mean abundance index of 29.6 for age-O winter flounder in late fall and early winter in 1988-
- 8. Estimated annual larval growth rates were based 89 was the largest in 13 years, which was another in- ;
on weekly mean lengths of larvac collected at the dication of the strong 1988 year class. The 6.mean = l lower river (station C) and in the bay (station EN). index generally correlated with beam trawl CPUE of Examination of water temperatures in these areas the same fish in the Niantic River during the previous showed that growth in the bay was positively summer, but not with the median otter trawl CPUE r correlated with water temperature, llowever, this of juvenile fish taken incidentally during the subsc- ; relationship was not apparent in the lower river, The quent February April adult spawning survey. For ex-lowest growth rates in the river coincided with the ample, the CPUE of juveniles taken during the 1989 greatest densities, suggesting density-dependent adult survey was 7.9, which was smaller than the y growth that may have been related to levels of value of 11.2 for 1988i Factors such as sampling & available prey. The annual dates of peak abundance in variability and differential distribution of juveniles the bay were also correlated to mean water within and outside of the river most likely affected the temperature in March and April, indicating that reliability of the otter trawl median CPUE as an indi-growth and the rate of larval development were cator of relative abundance for a particular year class, i related. !
- 13. Most correlations among abundance indices of
- 9. The greatest larval mortality was during Stage 2 various winter flounder life-history stages were not i of development, which is when first feeding occurs. significant. Variability due to compensatory proces-This may be considered a
- critical period" for winter ses did not appear to be a likely explanation for this Dounder, Totallarval mortality from 1984 through lack of correlation.
1989 ranged from 84.6 to 97.9%, with a mean instantaneous rate of 2.92, Evidence of density-depen. 14. Annual standardized catches were partitioned into dent mortality during larval development was indi- various age classes by using an age length key for ' cated by increased annual mortality with increasing Niantic River winter flounder. Assuming on instan-annualegg production. taneous mortality rate of 0.85, it was apparent that - targe fractions of age 3 (82%) and age-4 (60%)
- 10. Post hirval age-O winter flounder have been sam- females did not enter the Niantic River spawning pied in Niantic River since 1983 and Niantic Bay grounds,' most likely because they were still since 1988. Larger numbers of larvac metamorphosed immature. Thus, Niantic River winter Dounder were in the bay, but because densities decreased greatly not fully recruited until ages $ or 6. Because correla-throughout the summer relatively few remained at the tion analysis showed little correspondence among car. ;
l end of the season. Abundance in the river peaked in ly life stages and abundance of older age-classes, i l late June and declined to levels of 5 to 10 fish per 100 year. class recruitment was determined from numbers . 2 !- m by the end of the season. Apparently few or no of aged spawners scaled up to population size by the young moved from the bay into the river, same factor used for parental stock estimates.- Throughout the years of study, growth appeared to
- l. ,
- have been inversely related to density, but mortality 15. The estimated recruitment for the 1985 year. class l= was apparently not influenced by abundance. was less than expected, given the parental stock size ,
and February water temperature for that year. The
- 11. The year. class in 1989 was much less abundant three parameter Ricker SRR with a negative February than the one for 1988, which was the strongest one temperature effect provided a conservative estimate for observed since the beginning of the sampling in a of 2.646. This value was within the range of es-1983. Winter flounder year class strength is pubably timates for a of 2.22 to 2.59 given by Gibson i influenced by events during the first summer of life (1989c) for several Southern New England winter following larval metamorphosis. Based on limited flounder stocksJ Two biological reference points comparisons, however, no correlation has yet been determined with the Ricker SRR for Niantic River found between the indices of abundance for age O fish winter flounder included the theoretical equilibrium size of the stock (Pg 43,659) and the fishing rate ,
Winter Flounder Studies 69'
t i i t I for recruitment overfishing (Fno: 0.868). average.
- 16. Basic life-table parameters, an initial spawning 20. Annual entrainment estimatos were compared j stock size, the three parameter estimates of the SRR, with indices of abundance for o' der life stages. No :
February water temperature statistics, and specific significant correlations were feend : hat would have in- ; model run simulation parameters were used to dicated aa adverse eff ect relaud to larval entrainment ! initialize LW winter flounder population model.~ Both on year class strength of winter flounder.' [ deterministic and stochastic model runs were made. ' In the latter,50 time-series replicates were generated 21. Results of probabilistic risk assessments concern- , with annual February temperature and a " noise" com. ing the long-term effect of year-class reductions due to .! ponent as random variales. The model was calibrated both higher fishing rates and larval entrainment under { with the stock recruitment data. Simulation studies three-unit operation provided the most conservative es - ! that repeatedly fit the SRR to random time-series of timates of stock reduction probabilities. 'Ihe most , model generated data produced estimates of and $ as likely stock reductions predicted were in the order of l precise or better than actual data and for n correctly in 5% to 10%, depending on the larval entrainment rates ! about 70% of the runs. simulated, and only in one instance among all the simulations conducted was the stock reduction greater >
- 17. The deterministic stock assessment investigated than 50% The probability of stock collapse was es- !
the response of the spawning stock to increasing ex. sentially zero for the conditions and impacts l ploitation by projecting the initial stock size under simulated, i different fishing rates. Predicted sustainable stock sizes were 39,539 female spawners at F=0.55,33,491 References Cited : at F=0.60, and 27,575 at F=0.65. The latter stock . i size represented a 40% reduction relative to the 1977 Arai, M.N., and D.E. Hay. 1982, Predation by [ 85 mean stock size, medusac on Pacific herring (Clupca harengus) lar- ; vae. Can. J. Fish; Aquat. Sci. 39:1537 1540,
- 18. A baseline or reference stock was created, consis- v ting of 50 replicates of a stochastic stock series under Arnason, A.N., and K.ll. Mills.1981. Bias and loss conditions prior to 1986 (two unit MNPS operation). of precision due to tag loss in Jolly.Seber es-The mean stock size generated was 39,M3, a value timates for. mark recapture experiments. Can. J. ,
very close to the deterministic equilibrium stock size Fish. Aquat. Sci. 38:1077 1095. of 39.595 for the same F (0.55). The variability ' (CV=38%) of the series appeared to be realistic, but Bailey, K.M., and R.S. Batty, 1984. Laboratory the maximum stock size of about 49,000 fish was study of predation by Aurelia aurelia on larvae of well below the record stock sizes of over 80,000 nsh cod, flounder, plaice and herring: development and that occurred in the early 1980s. The tendency of the vulnerability to capture.- Mar. Biol. (Berl.) simulated population to produce smaller dominant 83:287 291, year classes suggested that fishing rates in the past were less than 0.55. Examples of simulated and ac- Bannister, R.C.A., D. Harding,' and S.J. Lockwoot tual age composition of the stock appeared to be in 1974. Larval mortality and subsequent year clas fairly good agreement. strength in the plalec (Pleuronectes platessa Ls Pages 2138 in J.H.S. Blaxter, ed. The early lift
- 19. The median larval density of 165.7 per 500 m3 history of fish. Springer Verlag,New York.
in entrainment collections in 1989 was about twice as i large as the value of 86.1 for 1988. However, the es. Begon, M.1979. Investigating animal abundance: I timated total number of larvae entrained (131.3 mil, capture recapture for biologists. University Park lion) was similar to the totals for 1986 88 (109.4 Press, Baltimore. 97 pp. ; 138.0 million) because of the smaller volume of water used by MNPS operation this year. About Bergman, MJ.N., H.W. van der Veer, and JJ, three fifths of the entrained larvac were in Stage 3 of Zijlstra.1988. Plalce nurseries: effects on recruit-development, which was similar to the long term ment. J. Fish Biol 33 (Suppl. A): 210-218. l l l 70 Monitoring Studies,1989 f
Bishop, J.A., and P.M. Sheppard.1973. An evalua. of winter flounder larvae within a Rhode Island tion of two capture-rwepture models using the salt pond. Estuaries 8:217 227.
- technique of computer simulation. Pages 235 253 in M.S. Br.rtlett and R.W. Hiorns, eds. The Crecco, V.A., and T. Savoy. 1987. Fishery manage-mathemaucal theory of the dynamics of biological ment plan for the American shad in the Connec-populations. Academic Press, London. ticut River. Connecticut Dept. Envir. Prot., Bu.
Fish., Spec. Pub. ,140 pp. Buckley, LJ.1980. Changes in ribonucleic acid,
- deoxyrihonucleic acid, and protein content during Cushing. D.H.1974. The possible density-depen-ontogenesis in winter flounder, recudop/ruronec. dence of larval mortality and adult mortality in les americanus, and effect of starvation. Fish, fishes. Pages 103 111 in J.H.S. Blatter, cd. The Bull., U.S. 77:703 708. carly. life history of fish. Springer Verlag, New York.
.1982. Effects of temperature on growth and biochemical composition of larval winter flounder , 1977. The problems of stock and recruit-PJcudopleuronectesamericanus. Mar. Ecol. Prog, ment. Pages 116 133 la J.A. Outland, ed. Fish Ser 8:181186, population dynamics. John Wiley and Sons New York.
Burton, M.P., and D.R. Idler. 1984. The reproduc-tive cycle in winter flounder, P3rudopleuronectes . and J.G.K. Ilarris,1973. Stock and recruit. americanus (Walbaum). Can. J. Zool. 62:2563 ment and the problem of density dependence. 2567. Rapp. P..v. Reun. Cons, int. Explot. Mer 164:142 155. Charnbers, R.C., and W.C. Leggett.1987. Size and age at metamorphosis in marine fishes: an . and J.W. Horwood.1977. Development of a analysis of laboratory reared winter flour der model of stock and recruitment. Pages 2135 in (Pscudopleuronectes americanus) with a review of J.H.Steele,ed. Fisheries mathematics. Academie variation in other species. Can. J. Fish. Aquat. Press. New York. Sci. 44:1936-1947. Danila, DJ. 1978. Age, growth, and other aspects
. W.C. Leggett, and J.A. Brown. 1988. Varia- of the life history of the winter flounder, Pscudo-tion in and among early life history traits of plcuronectcs americanus (Walbaum), in southern j laboratory reared winter flounder Pscudopleuronce. New Jersey. M.S. Thesis, Rutgers University, L tes americanus. Mar. Ecol. Prog. Ser 47:1 15. New Brunswick, NJ. 79 pp.
I Christensen, S.W., D.L. DeAngelis, and A.G. Clark. Dimou, N.K., and E.E, Adams. 1989. Application 1977. Development of a stock progeny model for of a-2.D particle tracking model'to simulate assessing power plant effects on fish populations. 'entrainment of winter flounder larvae at the !, Pages 196 226 in W. Van. Winkle, ed. Proceed. Millstone Nuclear Power Station. Energy Labor-ings of the conference on assessing the effects of atory Report No. MIT FL 89-002. Massachusetts power plant induced mortality on fish populations. Institute of Technology, Cambridge, MA. 73 pp. Pergamon Press, New York. Draper, N., and H. Smith.1981. Applied regression
, and C.P. Goodyear. 1988. Testing the analysis John Wiley and Sons, New York. 709
- j. validity of stock recruitment curve fits. Am, pp.
l Fish. Soc. Monogr. 4:219 231. Dunn, R.S.1970. Further evidence for a three year Cormack, R.M.1968. The statistics of mark recap- oocyte maturation time in the winter flounder ture methods. Oceanogr. Mar. Biol. Ann. Rev. (Pscudopleuronectes americanus). J. Fish. Res. 6:455 506. Board Can. 27:957 9(0. Crawford, R.E., and C.G. Carey. 1985. Retention , and A.V. Tyler. 1969. Aspects of the Winter Flounder Studies :71-
i anatomy of the winter ficunder ovary with winter nounder larvae. Pages 130 in S.B. Sails, : hypotheses on oocyte maturation time. J. Fish. ed. Fisheries and energy production:'a syra. Res. Board Can. 26:19431947. posium. D.C. Heath and Co-,lexington, MA. Garrod, D.I., and II.W. Jones. 1974. Stock and Hightower, J.E., and RJ. Gilbcrt. 19f4, Using the : recruitmem relationships in the Northeast Arctic Jolly.Seber model to estimate po;sulation size,' } cod stock and the implications for the management mortality, and recruitment for a reservoir fish of the stock, J. Cons. int. Explor. Mer 36:35-41. population. Trans. Am. Fish. Soc. 113:633 641, Gibson, M.R. 1937. Preliminary assesstnent of Iljorleifsson, E.1989. (Abstr.). Condition of win. winter flounder (Pscudoplcumaccresumcricanus) ter flounder larvae in Narragansett Bay as measured stocks in Rhode Island waters. Rhode Island Div, by RNA/DNA ratio Workshop on winter floun. [ Fish Wildi., Res. Ref. Doc. 87/7. 51 pp, der biology, Mystic, CT, December 5 6,1989. j 1989a. A study and comparison of winter Hjort, J 1926. Fluctuations in the year classes of flounder growth rates in several Northwest Atlan. Important food fishes. J. Cons, int. Explor. Mer i tic populations from New Jersey to Newfoundland 1:5 38. (not seen, cited by May 1974). 1 with emphasis on Rhode Island. Rhode Island Div. Fish Wildt., Res. Ref. Doc. 89/5. 28 pp + 3 - Houde. E.D. 1987.' Fish early life history dynamics i fig, and recruitment variability. Am. Fish Soc, ; Symposium 2:17 29.
.1989b. Variation in size and age at maturity !
in winter flounder: implications for fishing ef fects llowe, A.B., and P.G. Coates.1975. Winter floun-
- on spawning stock biomass levels. Rhode Island der movements, growth and mortality off Mas. -i Div. Fish Wildi., Res. Ref. Doc, 89/6. 26 pp + 4 sachusetts. Trans. Am, Fish Soc. 101:13 29.- ;
flg. ' ilowell, W.ll., and R; Langan. 1987. ' Commercial +
.1989c. Stock recruitment relationships for trawler discards of four flotmder species in the Gulf winter flounder in the S, New England area and of Maine. N, Am. J. Fish. Man; 7:617.- ...
revised fishery reference points. Riule Island Div. . i Fish Wildt., Res. Ref. Doc. 89/9. 10 pp + 5 fig. Jeffries, H.P., A. Keller, and S. Hale.1989, Predic. - ting winter flounder (Pscudoplcumnectes Goodyear, C.P. 1977. Assessing the impact of americanus) catches by time scries analysis. Can. power plant mortality on the compensatory reserve J, Fish. Aquat. Sci. 46:650-659, of fish populations. Pages 186 195 in W. Vim Winkle, ed; Proceedings of the conference on ns. _ , and M. Terceiro. _1985. Cyck of changing sessing the effects of power. plant induced mor-abundances in the fishes of the Narragansett Bay tality on fish populations. Pergamon Press. New area. Mar. Ecol. Prog; Ser. 25:239 244. York. Jolly, O.M. ' 1965. Explicit estimates from cap.
, and S.W. Christensen. 1984 lilas. ture recapture data with death and immigration climination in fish population- models with stochastic model. Biometrika 52:225 247c :
stochastic variation in survival of the young, . Trans. Am. Fish, Soc. 113:627 632. Klein MacPhee, G.1978; Synopsis of biological - ddla for the winter flounder, Pscsulopleuronectes l llennemuth, R.C., J.E. Palmer, and B.E. Ilrown. americanus (Walbaum). NOAA Tech. Rep. , 1980. A statistical description of recruitment in NMFS Cire. 414. 43 pp. eighteen selected fish stocks. J. Northwest Ati; ; Fish.1:101 111. Kuipers,11.1975. On the efficiency of a two met e ' l beam- trawl for juvenile plaice (Plcuronectes liess, K.W., M.P. Sissenwine, and- S.B; Saita, platessa); Neth. J. Sea Roa. 9:69 85. 1975. Simulating the impact of entrainment of ; 1 72 Monitoring Studies,1989 ) l
o Laurence O.C. 1975. Laboratory growth and (Walbaum),'on the Atlantic coast. J. Fish Res.- 1 - metabolism of the winter flounder heudw Board Can. 20.551586. pleuronectesamericanus from hatching through . __ i metamorphosis at three temperatures. Mar. Biol. . McFadden, J.T.1977. An argument supporting the (Herl.) 32:223 229. reality of compensation in fish populations and a 3 plea to let them exercise it. Pages 153183 in W.1 t
.1977. A bioenergetic model for the analysis Van Winkle, ed. Proceedings of the conference on - i of feeding and survival potential of winter floun. assessing the effects of power plant induced mor. .:
der, fxudoplcuronectes americanus, larvao during tality on fish populations.' Pergamon Press, New - ! the period from hatching through metamorphosis. York. - Fish. Bull., U.S. 75:529 546. . Modlin, R.F. ' 1976. Life history, ecology, and Lobell, MJ 1939. A biological survey of the salt - population dynamics of Crangon septemspinosa i waters of Long Island,1938. Report on' certain (Say)(Decapoda: Caridae) in the Mystic River es. fishes. Winter flounder (Pseudopleuroncetes tuary, Connecticut. Ph.D. Thesis, University of ~ - americanus). Suppl. 28th Ann. Rep., N.Y. Cons. Connecticut, Storrs CT. 91 pp. ; Dep., Pt. I:63 96 , Moller, H. 1984. Reduction of a larval herring' ~l Lockwood, SJ.1980. Density dependent mortality - population byjellyfish predator. Science (Wash., . j in 0-group plaice (Pleuronectes platessa L.) D.C.) 224:621622. j populations. J. Cons. int. Explot. Mer 39:148 . l$3. Moore, D.W 1978. - Sand shrimp. Pages 242 250-in T.R. Tatham, DJ Danila, and D.L. Thomas,
] ,
Lorda, E.C., and V.A. Crecco, 1987. Stock-recruit. and Associates. Ecological studies for the Oyster .; ment relationship and compensatory mortality of Creek Generating Station. Progress report for the :j American shad in the Connecticut River. Am. period September 1976 August 1977, Vol. I. Fini Fish. Soc. Symposium 1:469-482. und shellfish. Ichthyological Associates, Inc., - ; Ithaca, NY. :
- Manly. BJ.F. 1971. . A simulation of Jolly's .
I method for analysing capture recapture data. Nichols, J.D. - B.R. Noon, S.L. Stokes, and J.E, " Biometrics 27:415-424 Hines 1981. Remarks on the use of capture recap- j ture methodology in estimating avian population' 'l Marshall, N., and S.D. Hicks. 1962. Drift of size. Studies in Avian Biol. 6:121 l?6.c (not 'i medusac and their distribution in relation to the seen, cited by liightower and Gilbert 1984). hydrography of the Niantic River, Connecticut. 4 Limnol. Oceanogr. 7:268 269. Northeast Utilities ' Service Company. (NUSCO).
- 1987c Winter flounder studies, in Monitoring the May, R.C. 1974. Larval mortality in marine fishes marine environment of Long Island: Sound'ati '
and the critical period concept. Pages 3 20 in Millstone Nuclear Power Station. Summary of J.H.S. Blaxter, ed. The early life history of fish, studies prior to Unit 3 operation.151 ppi' Springer Verlag,New York. _ . . . l e 1988a. Winter flounder studies. Pages 149. ; a Mayo, R.K., A.M. Lange, S.A. Murawski, M.P. Sis. 224 in Monitoring the marine environment of - i senwine, and B.E. Brown.1981. Estimation of Long Island Sound at Millstone Nuclear Power
- discards in mixed trawl fisheries off the northeast 1
Station. Three unit operational studies,1986-coast of the United States, based on bottom trawl 1987, survey catches. NMFS, Northeast Fisheries Cen-ter, Woods llote, MA, Lab. Ref. 8118. (not .1988b. The usage and estimation of DELTA wen, cited by llowell and Langan 1987), means. Pages 311320 in Monitoring the marine !
. environment of Long Island Sound at Millstone q
- McCracken, F.D.1963, Seasonal movements of the Nuclear Power Station. Three unit operational winter flounder, Pseudop/ruronectesamericanus studies, 1986 1987. i 1
i l Winter Flounder Studies 73- F q _ ., , ,, , x __m - - . _ _.
i 1
.1989. Winter flounder studies. Pages 239 .1975. Computation and interpretation of .
316 in Monitoring the marine environment of biological statistics of fish populations. Bull, i Long Island Sound at Millstone Nuclear Power Fish. Res. Board Can, 191. 382 pp, Station. Annual report 1988. Roff, D.A.1973. On the accuracy of some mark-Olla, B.L., R. Wicklund, and S. Wilk. 1%9. Be- recapture estimators. Occologica (Bor!.) 12:15 34 havior of winter flounder in a natural habitat. i Trans. Am. Fish. Soc. 98:717 720. . 1981. Reproductive uncertainty and the evolution of iteroparity: why don't flatfish put all Parrish, B.B.1963. Some remarks on the selection their eggs in one basket 7 Can. J. Fish. Aquat. processes in fishing operations. Int. Cornm. Sci. 38:968 977. Northwest Atl. Fish. Spec. Pub. 5:166-170. l Rogers, S.I., and SJ. Lockwood. 1989. Observa. ; Pearcy, W.G.1962. Ecology of an estuarine popula, tions on the capture efficiency of a two-metre tion of winter flounder Pseudopleuronectes amer- beam trawl for juvenile flatfish. Neth. J. Sea Res, icanus (Walbaum). Bull. Bingham Oceanogr. 23:347 352. Coll.18(1):178. Rubinstein, R.Y.1981. Simulation and the Monte Pennington, M.1983. Efficient estimators of abun. Carlo method, John Wiley and Sons, New York, dance for fish plankton surveys. Biometrics . 278 pp. 39:281 286. Saila, S.B.1%1. A study of winter flounder move. !
. 1986. Some statistical techniques for es. ments, Limnol.Oceanogr 6:292 298.
timating abundance indices from trawl surveys. Fish. Bull., U.S. 84:519 525. .1962a. The contribution of estuaries to the offshore winter flounder fishery in Rhode Island, Perlmutter, A ' 1947. The blackback flounder and its Proc, Gulf Caribb. Fish. Inst.14th Annu. Sess. ' fishery in New England and New York. Bull. Ilin- 1961:95 109. ; gham Oceanogr. Coll.11:192.
.1962b. Proposed hurricane barriers related to ,
Poxton, M.O., A. Eleftheriou, and A.D. McIntyre, winter flounder movements in Narragansett Bay, 1982. *lhe population dynamics of 0 group flat- Trans. Am. Fish. Soc. 91:189195.
- fish in the Clyde Sea area. Est Coast. Shelf Sci.
14:265-282, S AS Institute Inc.1985. SAS user's guide: stans-l tics. Version 5 edition. SAS Institute Inc., Cary,
, A Eleftheriou, and A.D. McIntyre. 1983, NC, 956 pp.
The food and growth of 0 group flatfish on nursery grounds in the Clyde Sea area. Est. Coast. Shelf Savidge, J.R., J.B. Gladden, K.P. Campbell, and J.S. Sci.17:319 337. Ziesenis.- 1988. Development and sensitivity J l analysis of impact assessment equations based on
. and N.A. Nasir.1985. The distribution and stock recruitment theory. Am, Fish. Soc.
population dynamics of 0-group plaice (Pleuronec- Monogr. 4:191203. ; ses platessa L.) on muscry grounds in the Firth of ; Forth. Est. Coast. Shelf Sci, 21:845 357. Saucerman, S.E.1989. (Abstr.) Distribution and productivity of juvenile winter flounder Reed, M., M.L. Spaulding, E. Lorda,it Walker, and (Pseudoplcuronccles americanus) in Waquoit Bay, S.II, Saila. 1984, Oil spill fishery impact assess- MA. Tenth Biennial Int Estuarine Res. Conf., ; ment modeling: the fisheries recruitment problem. Baltimore, MD, October 812,1989, ; Est. Coast. Shelf Sci. 19:591 610. ' Scott, W.B., and M.G. Scott. 1988, Atlantic fishes Ricker, W.E.1954. Stock and recruitment. J. Fish. of Canada. Can. Bull. Fish. Aquat, Sci. 219. Res. Board Can. I1:559-623, - 731pp. 74 Monitoring Studies,1989
.l
y i i
- i 4 !
' Shepherd J.G.1982, A versatile new stock-recruit- Stocle, J., C. Clark, P. Larkin, R. Lasker, R. May, . j ment relationship for fisheries, and the construc- B. Rothschild, E. Ursin, J. Walsh, and W.
tion of sustainable yields curve J. Cons, int. Wooster. 1980. Fisheries ecology: some con- ' Explor. Mer 40.67 75. . straints that impede our understanding. Ocean Science Board, National Academy of Science, l
'~
Simpson, D.O. l1989. Codend selection of winter Washington, D.C. -; flourgict Pseudopleuronectesamericanus. NOAA .
.. -l Tech. Rep. NMFS 75. - 10 pp. , and R.R.C. Edwards.1970. The ecology of ' !
0-group plaice and common dabs in Loch Ewe. ! Sissenwine, M.B. 1984. _ Why do fish populations IV. Dynamics of the plaice and dab populations. : vary? Pages 59 94 in R.M. May, ed. Ex. J. Exp. Mar. Biol. 4:174 187. j ploitation of marine communities. Springer Ver- , lag, New York. Stuart, A., and J.K. Ord.1987. Kendall's advanced l theory of statistics.1Vol. l. Distribution theory.
, and J.G. Shepherd. 1987. An alternative - Oxford University Press, New York. 604 pp. .!
perspective. on recruitment overfishing and ] biological reference points. Can. J. Fish. Aquat. Tuljapurkar, S.D., and S.H. Orzack. 1980. Popula- r Sci. 44:913 918. tion dynamics in variable environments. I. long-run growth rates and extinction. Theoret. Pop. Smigielski, A.S. 1975. ~ llormonal induced ovula- Biol.18:314 342. tion of the winter flounder, Pseudopleuronectes . americanus. Fish. Bull., U.S. 73:431 438. Vaughan, D.S.1981. An age structure model of yel- 1 low perch in western Lake Eric. Pages 189 216 in . . Smith, E.M., E.C. Mariani, A.P. Petrillo, L.A. D.O. Chapman and V.F.' Gallucci, eds. Quan . f Gunn, and M.S. Alexander. 1989. Principal titative population dynamics. ~ International Co-fisheries of Long Island Sound,1961 1985. Con- operative Publishing Ilouse, Fairland, MD. l necticut Dept. Envir. Prot., Bu. Fish., Mar. Fish. .
}
Proi, xt 47 pp. + app. Veer, ll.W. van der.1985 ' impact of cocienterate' [ predation on larval plaice fleuronectes platessa and Smith, W.O., J.D. Sibunka, and A. Wells. 1975. flounder flatichthysflesus stock in the western . Seasonal distributions of larval flatfishes (Pleuron- Wadden Sea. Mar. Ecol Prog. Scr. 25:229438.
> ' ectiformes) on the continental shelf between Cape .
Cod, Massachusetts and Cape Lookout, North . 1986, Immigration, settlement, and density. -! Carolina, 1965 1966. NOAA Tech. Rep. NMFS dependent mortality of a larval and early postlan al - , SSRF 691. 0-group plaice (ficuronectes platessa) population , in the western Wadden Sea. Mar. Ecol. Prog. Set, : Snedecor, O.W. and W.C. Cochran.1967. Statisti- 29:223-236. j cal methods.- The Iowa State University Press,, . . _.
'L Ames, I A. 593 pp.
l . and M.J.N. Bergman. 1987 : Predation by. '! crustaceans on a newly settled 0-group plaice Sokal, R,R,, and F.J. Rohlf. 1969. Biometry, fleuronectcsplaicssa population in the western-
'{
i W.ll. Freeman and Company, San Francisco. 775 Wadden Sea. Mar. Ecol. Prog. Ser 35:203 215.' -t Pp. Ware, D.M,1980. Bioenergetics of stock and recruit- ; Southwood. T.R.E. 1978. Ecological methods, ment. Can. J. Fish. Aquat.' Scic 37:10121024. llalstead Press, New York. 523 pp. Whitehouse, S.T.1989. Bottom dwelling shrimp , Spaulding, M.L., S.B. Saila, E. Lorda,11. Walker, E. and their role in Narragansett Bay. Maritimes_ ; Anderson, and J.C. Swanson. 1983. Oil spill (University of Rhode Island Graduate School of l ! fishery impact assessment model: application to Oceanography) February 1989:1516. .j
- selected Ocorges Bank fish species. Est. Coast.
Shelf Sci. 16:511 541. - 4
?
5 Winter Flounder Studies ' 75: I/
.{
t
. . - _ , , , . - - , ~ . . , . . - . , , _ , , - _ ,, 4 ~,- . , _ - , _ . .
t Appendix Scaling factor for multi age 7tcruitment R3,is = Ny[(fm3) + (S 3)(fm4) + (S 3)($4 )(fm3) + ... z Stock recruitment theory (Ricker 1954) was develope 3 for semelparous fish that spawn only once before where the summation within the brackets is the scal-dying. The extension of this theory to iteroparous ing factor ASF defined in Equation Al, Rewriting fish (i.e., multi age spawning stocks) involves the this summation in a more compact form produces the scaling of the recruit index to account for the f nal expression for the scaling factor as: ' reproductive contribution of the fish over their entire lifetime. The appropriate scaling factor for this pur- 15 g.1 pose is based on the life span of the fish, the matura-tion rate, and the annual survival rate, all of which are ASF = fm3 + [ (fmi(( Sj) g,4 j,3 (45) specific to each species and particular stock. This
- age structure scaling factor
- is defined here as the This equation is similar to the product of the
- stock quantity ASF such that-value" and " fecundity per unit stock" terms defined by Christensen et al. (1977), also refened to as VE by Rm., = ASP N, (Al) Christensen and Goodyear (1988). The only dif-ference between ASF and the quar.tity VE is that the where the subscripts m and n denote the age at which latter incorporates fecundity rates because it applies to maturation first occurs and the oldest age attained by recruitment expressed as eggs instead of spawners, the fish, respectively; N, is the total number of -
female fish surviving to age m; and R.,. is the ag- Mortality through the first year i gregated number of mature female fish that survive to spawn from age m through age n (i.e., a year class The most critical part of the winter flounder popula-potential recruitment). For the Niantic River winter tion model described in this repon was the mathe-flounder where n=3 and m=15, the scaling factor ASF matical representation of fish mortality from egg can te derived as follows: through the first year (Eq.18 in Materials and Methods). Because the reproductive cycle and popula- ' R3 .15 = I N,(Imj) for i = 3,4, ...,15 (A2) tion growth were modeled after Ricker's form of stock-recruitment Equation 18 had to include the mech-where N; is the number of female fish surviving to anisms underlying Ricker's SRR for a multi age age land im; is the fraction of mature female fish h. stock and contain the three parameters fitted to the data (Eq. 8 in Materials and Methods), in addition, the age group i Because the number of fish surviv-the model assu.ned that all compensatory processes ing to age i+1 is the number N/ m the previous year and stochastic variability occurred before the fish be-times the survival rate Si through that year, Equation came 1 year old. A2 can te rewritten as: The derivation of Equation 18 followed Ricker's R3.15 = (N 3)(fm3)+(N 3)(S3)(fm4)+ (N 3 )(S3)(S4)(fm3) method to obtain total mortality Zo from egg to
+ ... + [(N3)(S3 )....(S 4)(Imts)) (A3) maturation (Ricker 1954), modified here to apply to multi age stocks and to the temperature dependent whert the number of fish surviving to age 4 is version of Ricker's SRR (Eq. 8). Under the assump-(N 3)(S3), the number surviving to age 5 is tion of steady state, the annual egg production is ,
(N4)(S3 )(S 4), and so on. Because N 3(the year class proportional to the number of female spawners in the stock, so that: size as fish become 3 years old) is a multiplier that nppears in all the terms of the above summation, Equation A3 reduces to: E, = P, FEC and P, = E, / FEC (A6) 76 Monitoring Studies,1989
where t denotes the year. P, is the total number of female fish that spawn in year t, FEC is the mean fecundity rate at equilibrium (female eggs per female spawner),and E, is the total number of female eggs spawned in year t, Ily substituting P, above and R, from Equation Al into the SRR model (Eq. 8), the latter becomes: ASF N3 = n(E, / FEC)exp( P,)cxp($Trew) (A7) which can le rewritten through algebrah manipula-tion as: N3/ E, = (n exp[ P, + $Treb]) /(FEC ASF) (A8) For these substitutions to be vGd, R,in Equation 8 (see Materials and Methods) must be the potential secruitment of the year class i as defined for the deriva-tion of ASF (Eq. Al). Then, the age 3 fernale recruits (N3 ) and the female eggs (E,)in Equation A8 are from the same year class and the ratio 3N / E, is the proportion of eggs that survive to age 3, By ex. pressing N3 in terms of the age 1 fish and their probability of survival to age 3 (i.e., N 3 = Nt1 S ,2). Equation A8 can le rewritten as: N i/E, = (n expl DP, + $Trebl)/(FEC ASF S1 2) (A9) where N / E, is the probability of survival from egg to age 1 and St ,2i s the probability of survival from age 1 to age 3 Finally, the total mortality fram c;:g through the first year is derived as: Zo,, = log,(N t / E,) = loge ([FEC ASPSi ,2]) / (n exp( SP, + $Trch]) (A10) which reduces to: Zo,, = loge (FEC) + loge (ASF) . loge (n) . $Tred - Z 1,2 + DP, (All) This final equation becomes Equation 18 when the stochastic term n, is added to simulate the uncertainty associated with the estimate of the parameter n (see Materials and Methods for additional details). 4 Winter Flounder Studies 77 i
Contents ; 6 Fish Ecology S tudies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 l Introd uction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 : Material and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 lehthyoplankton program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 1 Trawl program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3 : Seine program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3 i Data analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 ; Ichthyoplankton monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 l Trawl monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 ! Seine monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . 8 8 l Entrainment Estimates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 i Selected Taxa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 i American sand lance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 i Anchovies . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . 92 i S il versides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 - G ru bby . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 6 Ta u tog . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 Co n ne r . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Concl u sion s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 S u mmary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 References Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 A ppendi x Table s . . . . . . . . . . . , , . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 10 APPENDIX l. List of fishes collected in the Fish Ecology sampling prog ra ms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . t i l APPENDIX 11. Total numbers of fishes caught by trawl and number of samples collected in each year (June May), 1976 1989 . . . . . . . . . . . . . . 113 'n APPENDIX 111. Total numbers of fishes caught by trawl and number of samples collected at each station (June May) 1976-1989 . . . . . . . . . . . . . I 15 h APPENDlX IV. Total numbers of fishes caught by seine and number of $ , samples collected in each year (June.May), 1976 1989. . . . . . . . . . . . . 117 C APPENDIX V. Total numbers of fishes caught b seine and number of samples colleced at each station (June May), 1976 1 89 . . . . ; . . . . . . , 118 f g
L Fish Ecology Studies Introduellon 2. Identify spatial and temporal patterns of fish abundance and establish the direction and extent of Fishes that are ecologically important and con- natural changes in these assemblages; and tribute to commercial and sport catches are found near the Millstone Nuclear Power Station (MNPS). Some 3. Evaluate the significance of observed changes . fish stay in the area throughout the year while others relative'to MNPS operation, with particular emphasis inhabit the locality seasonally for feeding, spawning on the period since Unit 3 tegan operating. or nursery 14ctivities. Both shore zone and demersal fishes arc important to the trophic structure of coastal To meet these objectives, NUSCO conducted three communities and consume a vast array of food items sampling programs which provide data on the (Richards 1963; Beck and poston 1980; Woodin available life history stages of those fishes suscep-1982; Bailey 1984; Witman 1985; LeMao 1986;. tible to impact: demersal trawl; shore-zone seine; and llorn and Gibson 1988). They also serve as prey as ichthyoplankton, including entrainment sampling. eggs and larvac and as juvenile and adults (Peamy and The life history and population characteristics of Richards 1962; llunter and Kimbrell 1980; Jamieson potentially impacted species are presented in this - el al,1982; Leak and floude 1987). Additionally, report and are evaluated to determine if MNPS has had fishing is an important element of coastal economics any detrimental effects on them. Data from June (Clark 1967). Millions of dollars are produced yearly 1988 through May 1989 are summarized in this by both commercial and sport fishing in Long Island report and compared to historical data from June 1976 Sound (LIS) and are added to coastal economy in through May 1989 for trawls, seines and entrained Connecticut (Sampson 1981; lilake and Smith 1984 larvac, and from June 1979 through May 1989 for Smith et al.1989), entrained eggs, and larvac collected in Niantic Bay. Operation of MNPS could affect fish assemblages in the area by increasing mortality, altering temporal Material and Methods or spatial distribution or lxith, impingement on the intake screens may remove juvenile and adult fish The materials and methods which follow are essen; from populations; however, impingement impacts tially the same as those used in previous years. Most have been mitigated with the addition of fish return data are summarized in June through May report sluiceways at Millstone Units 1 and 3. Also, eggs years, which includes data collected imm June of one and larvae of various fish species suffer mortality year through May of the following year. Thus, the when they are entrain:d through the condenser cooling report year 1988 89 included data from June 1988 water system. The effects of increase 41 mortality rates through May 1989. Because of occasional overlap in on the abundance of fish populations depends upon the occurrence of a species during the.May Junc - size, life span, age structure, and the effectiveness of transittorud period, species specific analyses are based any compensatory mechanisms. Spatial distributions on the actual periods of occurrence instead of being of local fish populations may be altered in response constrained to June 1 as the common starting peint, to the thermal effluent or changes to the physical- When a species season of occurrance crossed a calen-habitat. dar year, the year was reported in the form *1988 89", but when the species only occurred during a calendar ,. In order to determine die impact of MNPS on local year, the year was reported in the form "1989*. fish assemblages, monitoring studies have been MNPS trawl catches of cunner and tautog were sum-established to meet the following objectives: marized by calendar year so that direct comparisons could be made to catches reported by the Connecticut
- 1. Describe the occurrence and abundance of fish in Department of Environmental Protection (DEP),-
the Millstone area;
- Marine Fisheries trawl survey data.
Fish Ecology Studies 81
E one day and one night sample taken biweekly from lehthyoplankton pmgram . September through Martn. Patred 0.61 x 3.3 m conical plankton nets, mounted on a bongo frame. Entrained fish eggs and larvae (ichthyoplankton) were towed to collect sarnples. Tows were taken in a - samples were collected toth day and night four times stepwise oblique pattern and sampling duration was 5 per week, March through May, three times per week minutes each at surface, snid, and bottom depths. from June through Seriember, und once per week Sample volumes were measured using one General from October through February. Sampling alternated Oceanics flowmeter in cach net and approximately weekly between the discharges of Units I and 2 when 300 m3 of beawater were filtered for each sample. Net plant operations permitted, and all samples collected mesh size was 333 pm, except for a period from were designated as having come from station EN mid. February through March, when 202-um mesh (Fig. A). A 1.0 x 3.6 m conical plankton net with nets were used to reduce the extrusion of yolk sac 333 pm mesh was deployed with a gantry system, winter flounderlarvae. Four General Oceanic flowmeters (Model 2030) were positioned in the mouth of the net to account for Plankton anmples were split using a NOAA 11ourne horizontal and vertical flow variations. Sample splitter (llotelho and Donnelly 1978) and ichthyo. volume (about 400 m3) was determined by averaging plankton were removed under dissecting microscopes. the four volume estimates from the flowmeters. Successive splits were completely sorted until at least
$0 larvac (and 50 eggs for samples processed for eggs)
Larvae were also collected in mid Niantic Ilay, were found, or until oneAalf of the sample was ex. station Nil (Fig.1). Two day and two night samples amined. Samples examined for larvac included all Nil were taken weekly from April through August,argl samples plus n'l EN samples collected from January 1KM . d -
- TRAWLS
() l , eII SEINES 1 MI
- PLANKTON NIANTIC RIVER l
l NiANTIC JORDAN BAY J COVE
. ca" . n. .
N s' ' ' 'I N ** y6g
- TT \ %ek i
sQ Ngg
.n. ;
Fig.1. Location of trawl. seine and ichthyoplankton sampling stations. t j 82 Monitoring Studies,1989 : I e l .
i t through May and July through December; for June, two (onc day plus one night) EN samples per week Data analyses were examined. Three day and three night EN samples :
~
collected in April through September were examined Potentially impacted taxa were identified, and ob-for fish eggs. Fish eggs and larvae were identified to served spatial distributions and temporal abundance -i the lowest practical taxon. Cunner and tautog eggs fluctuations were assessed to determine possible were differentiated from a weekly composite sampic impacts. Indices of fish abundance were selected on of their eggs using the criterion of bimodality of egg the basis of underlying distributional assumptions; ; diameters (Williams 1967). Ichthyoplankton den- failure of the data to conform to these assumptions ! sities were reported as no/$00 m3 may reduce the precision of the estimates or, worse, provide biased results. The 6 mean was selected to 1 describe abundance tecause it is the rest estimator of a population mean that approximately follows '.he I Trawl program lognormal distribution and contains many retos I (liennemuth ct al.1980; Pennington 1983, 1986). Demersal fishes were collected using a 9.1 m otter The calculation of this index and its variance estimate : trawl with a 0.6-cm cov end linct. Triplicate bottom was described in detail in NUSCO (1988a). The 6- [ lows were made biwcekly throughout the year at six mean was used as an index of abundance for juveniles 1 stations: Ninntic River (NR), Jordan Cove (JC), and adults collected in the trawl and seine programs, ~ Twotree Island Channel ('IT), Bartlett Reef (BR), for larvae and eggs collected at EN, and for larvac Intake (IN) and Niantic Ilay (NB)(Fig.1). A standard collected at NH. The 6 mean indices for ichthyo- [ tow was 0.69 km and this distance was measured plankton were weighted by the largest number of . using onboard radw. W hen excessive k>ading of the samples ever collected in a week to standardire data trawl net occmted by macroalgae and detritus tow across weeks and years. For any sgecies that occurred distances were shortened but, catches were standardized seasonally, the data for calculating the 6 mean were to 0.69 km. Catch was expressed as the numter of restricted to its period of occurrence to climinate zero ! fish per tow and up to 50 randomly chosen values in the distribution tails. Because ichthyo. ;i individuals of certain selected species per station were plankton data were weighted and the periods of oc. [ measured (total length) to the nearest milkmeter, curence for less abundant species were redefined this year, previously reported annual 6 mean lehthyo- ! plankton indices (NUSCO 1989) may differ some- ! what from those reported here, j l Sem, e program (' l To investigate the presence of long tcrm trends in j Triplicate shore zone hauls were made parallel to the abundance data, running averages based on the 6- , l the shoreline at White Point (WP), Jordan Cove (JC), means were calculated from the beginning of each : and Giants Neck (ON), monthly from November time scrics. For example, the 1989 running 6 mean ! through March and biweekly from April through was calculated using all data from June 1976 through : October (Fig.1), using a 9.1 x 1,2 m knotless nylon May 1989, and the 1988 running 6-mean was cal. j seine net of 0.6 cm mesh. A standard haul was 30-m culated using data from June 1976 through May and this distance was measured using the pace 1988. The running 6 mean is a stable statistic, with methmt. Collections were made between the period of small year to-year fluctuations so long term trends are ! l 2 hours before and I hour after high tide; generally all more apparent, three stations were sampled the same day Fish in cach haul were identified to the lowest possible taxon, in past repons (NUSCO 1987,1988b), the n-counted, and the total length of up to 50 randomly parameter estimated from fitting the Gompertz func. t selected individuals of each species fmm each replicate tion to cumulative density data was used to describe ; was measured to the nearest millimeter. Catch was annual abundance of ichthyoplankton collected during . expressed as number of fish per haul, their season of occurrence.The form of the Gompertz [ t f
.t Fish Ecology Studies - 83 l i
~"
;i functke is: index was chosen for use for all abundance annlysesi. .
Ci a u(capl Sexp( wt)]) . Even though the a parameter of the Gomportz funci ; tion was dropped as an index of abuhdance, the- : whwe Ci = cumulative density (no/$00 m3) at time t ' Gompent functim was used to doennine the time @ i ! t' a timoln days imm the date when the peak abunknce M mew iMyoplaWon stock , 1 Time of peak abundance was estimated as the date ti-
- larvae generallyappear - -
a . = total or asymptotic cumulative density N W 4*NENN NON M W l> p , gg;, p,,,,, function given by the equation: 1 m3 11 = (loge $) It . , Nonlinear least square estimates of these parameters . . - -
~~
and their 9$% confidence intervals were obtained by-. The presence of density depcmkmt mortality durm.g" . fitting the Comperte function to the. cumulative; de early Me history stages would lessen the effect of - j losses due to entrainment, locause the natural sur- ,.i mbundance data. This year the need for two different abundance indices, annual 6 mean density and the vival would be better when density is lower ;When' - cumulative abundance index based on the u purameter abundance estimates of both eggs and larvae of a - ? fnwn the Comportz function, was evaluated. nioth of species were ' apaHabice the, presencet ore 3 these indices were calculated from cach of the fol- density dependent ,nortality was investigated using '
-[
lowing data series: anchovy (Anchoa milchilli and A. de following relaimnship (Ricker 1975); t hepsetus), tautog (Tautog onit/s) and cunner A (Tautogolabras ad.tpersus) eggs, and anchoyy, loge M) = a + bB ? ~ t
}
American sand lance (Ammodytes americanus) and . .t grubby (Afymocephalus senaeus) larvac collocied at where L =lanalabundanceestinate j EN and Nil. A correlation analysis was used to : ' E megg abundance cuinwie; , a detenninc if a relationship existed between these two a minwrcept . : .. . 7 indices. Significant relationships (similar to the : b = slope of density dependent mortalityf ~! eunner egg example in Fig. 2) were found for all .- series ( t2= 0.69, pc0.01 for anchovy larvac at Nil if die slope (b) is significantly different from reto and - 'j amith 037, pc0.001 for all other series). Although . positive, then the density dependent mortality is' the two indices behaved similarly, the confidence depensatory; if it is negative, then mortality is com. J genaamry,
]-
intervals for &nwans are more precise, the &mcan s
' l.
Annual entrainment estimates were calculated for
' dominant lchthyoplankton ' species collected at EN,; I]
i " g sme p.om t ""4 These estimates were obta.ined by multiplying the median density at EN during the period when 95% ofi
] '
p me. a species' total annual abundance occurred times the - C total volume of water passed through MNPS during1 4 4
. the same period. A nonparametric method (Snedecor '
${ ,
85* '
- and Cochran 1967) was used to construct 95% con- j]
coo fidence intervals around each median density aml ;j
,,- corresponding entrainment estimate. '
lj
*$tmo so che so do - As stated previously,' seine sampling effort wasi j i
stratified by season,'and length frequency data needed ? CtNUt.A11VE ABUNDANCIMn PARAMimily l Fig. 2. Linear relationship between the annual 6 mean to 12 Weighted to account for unequal effort during the ( year,J BecauscLseine sampling effort from April
]
~
j density (noJ500 m3) and the annual cumulative abundt . through October was twice that during the remainder 1 ) ance index (n parameter from the comporta function) of of the year, length data collected from Novemberc j cunner eggs, through March were weighted by a factor of two? d
, o q
d
=t
-M Monitoring Studies,1989
]
]
j g - - - -.. . __ - . , ., u , . - . _ _ . . _._ . , . ,. _ at
Data on the annual abundance of fishes in LIS and mation, in addition to providing entrainment es-adjacent areas were examined to determine if changes timates. Seven egg taxa were collected at EN in ' observed in the Millstone area were localized or sufficient numbers to calculate 6 mean densities ; evident over a larger area. Trawl data were available (Table 1). Cunner eggs were most abundant and, ; from the DEP random trawl survey in LIS, from except for 1986 87, levels of abundance remained 1984 through 1989 (P. Ilowell, pers. comm.), relatively consistent from year to year. Arnual Sufficient data were available for cunner and tautog 6 mean densities were also relatively consistent over - catch comparisons from these regional data sets. In time for tautog eggs, but 6 mean densitics were our 1988 annual report (NUSCO 1989), the Uniser. highest in 1985 86 and 1987 88. Densities of sity of Rhode Island Graduate School of Oceanog. anchovy eggs have fluctuated considerably from year ; raphy fixed trawl survey in Narragansett Bay, RI, to year and the 1988 89 value was the lowest record- ' 19591987 (Jefferies et al.1988), and Marine ed. Egg densitics of windowparse flounder more than > Research Inc. trawl survey in Mount ilope Bay, R1, doubled since 1985 86. Fourbeard rockling 1975-1985 (Jefferies et al.1988) were compared to (Enchclyopus cimbrius) egg densities in 1988 89 NUSCO results. No new data were available from were the highest recorded. these sources, so similar comparisons were not made. i The 1988 89 larval densities were within historic ranges, except fourteard rockling densities which were higher this year than in any previous year (Tables 2 Results and Discussion and 3). Anchovies, the dominant larval taxon, had , densities that were higher in 1988 89 than in 1987-l In the Millstone area,118 egg, larval, juvenile and 88, but were still low compared to historical values, adult fish taxa have been collected in ichthyo-plankton, trawl, and seine samples from June 1976 Larvae of three summer spawners: anchovies, - through May 1989 (Appendix I). The most common cunner and tautog have exhibited low abundance since . were winter flounder (Pscudoplcuronccles 1984 85 at both EN and Nil This phenomonon was ~ americanus), anchovies (Anchon mitch/lli and A . investigated by comparing annual abundance of each l hcpsetus), silverside (Afenidia menidia and Af. beryl- species to its long term average abundance. The lina), grubby (Afyoxocephalus acnatus), American abundance of anchovyi cunner and tautog larvae sand lance (Ammadytes americanus), skates (Raja relative to the long term average abundance was
~crinacca, R. occ/ lata, and R. cg/anteria), scup calculated by dividing the annual 6.mean densities .
(Stenotomus chrysops), windowpanc (Scophthalmus (no/500 m3) for each species by the 6-mean density [ aquosus), tautog (Tautogn onitis), and cunner ' (no/500 m3) for the entim data series (series 6-mean). (Tautogolabrus adtversus). These taxa were typical of Fluctuations were similar (Fig. 3) suggesting that the fish assemblages found in New England waters same factors probably influcnced survival of all three (Ovaitt and Nixon 1973; Salta and Pratt 1973; larval taxa. Many researchers have linked recruitment Jefferies et al 1988) and in LIS (Greeley 1938; success with water temperature (Cushing 1973,1977; Warfel and Merriman 1944; Wheatland 1956; Sissenwine 1974,19841 Roff 1981). To determine Richards 1959; Pearcy and Richards 1962; Mcliugh the relationship between water temperature and the 1972; Geomet Tech,1983). Following is a summary abundance of anchovy, tautog and cunner larvac, the of the predominant fishes in the Millstone area. yearly 6-mean larval densitics of these three species i were regressed against' MNPS summer water ' temperatures, but no significant relationships were 1 Ichthyoplankton monitoring found. Other explanations for simultanenously low larval abundance for these three taxa may be heavy , Fifty.nine ichthyoplankton taxa have tven collected predation, or low prey availability (floude 1977, ! l- in MNPS sampling programs (Appendix !). Annual 1978a,1978b; Leak and floude 1987). While there - 6 mean densities were calculated for the most abun- does seem to be some similarity among the abun-dant fish eggs and larvae collected at EN and larvae dance patterns of these three taxa, the mechanism collected at Nil. Ichthyoplankton collected at EN were controlling it is unknown. . used to calculate seasonal density estimates for com- ! parison of abundance and species composition infor. Fish Ecology Studies 85 ! 5
I Tall 3 f. Tin Emean' densny (noJ500 en ) of8the most abundant fish eggs collected at I.N for each soport yeat during June 1979 through May 1989, im. 70.ao k9. a t ti.12 12.a3 13.a4 ad.a3 13.h6 E6.s7 s7.ta ns.ko 7aut<vol6rm esperse $570 8223 .5171 3501 .7068 5719 7484 2969 5002 5395 7aurognosish- 1364 2642 2647 2244 2l14 -2157 3237 2756 3011 2260' Anchos app, 1447 124$ 1080 165 2257 4880 145 910 ' 89 38 Scophthalmw agnosw $0 63 65 34 - ' 19 71 365 181 $20 ) 178 Prionorm spp. 61 206 398 385. 425, 156- 367 82 63- 89 Sataaromw thrysops - 21 1 133 113 98 194 25 69 31' 4 1:=chelyopas ciaibrim 22 Il . 31 34 4 ' 10 f 14 - ' 55 -58 65
- Data seasonally eesincted to May 22. July 23 for Tautogolalew asperse, so May 23. August 25 for Tautoga onisis, to June l$. August 5 :
for Anchas spp., to May. August for Scop 4thalmw aguarw to July, August for Prionotw spp., to May July for Sitnotomus chrysops, and to April Aug.sst for 1:nchelyopus cimbriw. TAllW 2. 'lle &mean' density (noJ500 m ) of8 d e most abundant fish larvae collected at liN for each rep >rt year dunng June 1976 through May 1989. Mn 76-77 77 75 78 70 79 80 R0 R1 81 82 R2 83 R3.B4 14.RS BS.R6 166.R7 B74R $R.89 Anthoa spp. 1152 931 483 2168 2430_ 5768 816 1421 302 . 1102 1244 126 359 Psewtoplewonerses americune 106 143 114 285 129 233. 297 : 210 ~ 180 87 109 .I16' 203. Ammodyses americanw 94 318 119 lil 136 21 27 18 9 3 13 41 31 klyoaccephalat menatas 41 38 36 38 107 72 68 $0 68 - 34 29 95 63 Pholis gunaellus 13 13 16 13 . 58 27 13 14 14- 22 - 4 26 9 11revoornia tyrannut 5 4 4 0 3 I 11= 23 < 2 41 3 2 : 6' 7autorolabrusserrrsus 29 58 1, 13 58 18 31 49 4 12 4 $= 9-Tautoga onhh 37 36 1 11 46 83 44 33 . 3 15 3 7 17 - Lipuris spp. 27 30 10 '16 22 5- 13 8 ; 36 1 4 42 - 18 Ulvaria subbyarca e 5 9' 14 14 16 17 - 6 4- 60 7 9 23*-41 Syngnaikan /mcas 4- 7 4 9 8 13 7 9; 9i 5 4' 6- 7 Enchelporat cimbrint 2 8 6 8 6 i: 6 13 $ $ 8 12 45 Scophshalmat aquosat 10 11 1 5 5 5. 2 13 : 3 -1. 4 3 5 Pri rifw seuscan'hw 14 3 1 2 11 17 9 9- 1 2: 3 0 9 Gobudae 6 3- 1 0 1 0 0 ~l 4 3 3 2 4 Priono#w spp. 2 2 0 1 3 18 0 4 i' 6 's 0- I klyosocephalat oceedetraspinosar 1 1 1 1 1 3 4 4 1 0- O' O 1 Stenotomus chrysops 5 8 0 4 6 8 1- 0- 0 0, 0- D' 0' Clyta harengw 1 1 1 0 6 1 0 1 ; O --- 2- -1 14 . I Cyacs.tiva rig. aft 1 3 0 6 0 7 6 3 0 2 1 0 1
- Data seaumally restricted to July-Septemlet for Anchoa spp., to March-June for Pseudopleuronectes americans,to Decomter.May for Ammodyses americanus, to February.May for hfyosocephalar aenaeus, so January-May for Pholis gunnellus, to July. December for .
Srtvecraia tyrannat, to June-August for Taurogolebrw aspersat, to June August for Tautoga omitis, to March May for/li wris spp., to April Sel. cmlet for Syngnathw /wcm, to April. June for Ulvaria subbyurcada , to April July for Enckelyopus cimbris, to May.Oetcher for Scophthalme aguosw, to June Septemhet for Perrilas triacanthat , to June November for Gobiidae, to Juneseptemtet for Prionorat : spp., to January May for Afyotocephalm actodecentrinosar, to June. August for Stenotomus chrysops, to February May for Clupea kartagat, to Jure August for Cynascion retahs. l 86 Monitoring Studies,1989
8 7 All!Ji3.1he & mean' densdy (noJ500 m ) or the most abundant fish larvae collected at Nil for each repon yeat during June 1979 through May 1989. Innon 7940 k0 81 kl.t2 R2 B3 83.r4 24 E3 8346 86;fL . 8748 ,,1gjg ' Anch<w app. 3801 5716 787) 2103 2k60 327 til7 1224 79 303 fstulopleuronectes americanat 222 129 l$8 317 187 $$ 6C 146 147 111 Ammalyses americanst 113 236 20 $4 $8 8 3 13 83 35 Tousogolabrav adtivrsat 92 143 96 l$1 198 37 30 8 10 28 hlyomocephalw eenarat 31 $4 28 39 24 18 26 28 119 44 Tausega omisis 49 89 91 110 119 28 44 12 13 29 fachslyopat timbrint 19 10 - 3 24 19 23 9 Il 19 54 Itsemortia tyranne 0 2 2 36 9 24 12 0 1 I
$cophshalmut aguata 24 12 7 17 30 14 5 6 7 10 Tholss gunnellis $ 24 14 7 8 '2 8 1 7 5 ftprilut triacanthat 9 18 37 31 35 2 18 6 1 11 Liurinopp t 12 23 4 15 4 14 1 5 $9 12 Syngaarke futcut 5 7 9 5 12 7 2 2 4 4 Ulvaris subb(urcaia 10 9 20 8 $ 7 5 6 ll 12 frionvint app. $ 4 34 13 8 3 7 $ 0 2 blyoaccephalue ocialetemspanosus 2 3 4 6 4 1 0 1 1 1 Paralichthys oblongut 1 3 8 6 9 l $ l 1 3 Cynoscion regalss 6 0 11 13 0 0 1 1 0 0 Stenosomar chrysefu 9 16 6 1 0 0 0 0 0 0
' Data seasonahy reitncted to July September for Anchos spp., to MarchJune for Pseafopleurone*ses americanut ,io Decembes-May for .-
Ammmlytes americanus, to June. August for Tautogolabrus odtretsus, to June August for Tautoga onitis, to February.May for blyoaccephalar ornaene, to July. December for lirewortia tyronent, to AprilJuly for Encholyopus cimbrius, to hlay Octol>er for Scophthalme aquatur, so Jan A1ay for Pholis gunnellut, to June September for reprilns triacenthut, to March May fer Liparis spp., to Apnl September for Syngsathat fmcus, to June-September for Prionorat app., to Aprildune for Ulvaria subbyurcata, to January May for hlyoaccephalme ocialecterup44atur, to June. August for Paralichskys oblongat, to June-August for Cynoscion regalis, to June August for Stenotomus chrysops. Trawl monitoring 8' movt Since 1976,105 taxa of juvenile and adult fishes
*"". {EE were collected by trawls at six stations in the ld' 4
Millstone area (Appendices 11 and Ill), Winter tj 3 [' flounder dominated the trawl catches and accounted for . over 40% of the catch from June 1976 through May - i i e g 1989, Five other taxa together accounted for another jy/,
/ ', r' .,
40% of the catch: scup (14%), windowpane (7%), l$',p ,, ' f, ,,[, * ' 8** anchovies (7%), skates (6%) and silversides (4%).
,,g*
< The 1988 89 trawl catch was the fourth highest in; u,,/
o , . . . , . . terms of numbers of fish caught with winter flounder 75 77 79 81 83 $$ 87 89 remaining as the most abundant species (45% of the YI!AR total catch), The 1988 89 trawl catch of winter flounder was the second highest in the 13 year series, Fig. 3. Relative abundance index of anchovy, cunner and only exceeded by 1982 83, The winter flounder is lautog larvae (the annual 6 mean density (noJ500 caught throughout the year and, because of its com-m3 )/the 6 mean density (noJ500 m3) for the entire data mercial and recreational importance, is discussed in L series, for each species). detail in a separate'section (see Winter Flounder Studies). The second most abundant species was the scup which accounted for 11% of the trawl catch in Fish Ecology Studies 87
1988-89; most scup were juveniles taken primarily 6-mcan catches for all stations combined. ne annual ;' from June through October at NB. De windowpane, 6-mean catch of each fluctt:ated widely, which is a resident demersal fish, was primarily (6296) trawled common for trawl catch data (Geomet Tech.1983, at the two deep water stations (1T and BR). De Pennington 1986.Jefferies et al.1988). %e 1988-89 ! number of windowpane taken in 1988 89 was similar 6-mean catches for all six taxa were within historical .i 10 the 13-year average. Young-of the-year anchovies ranges (Table 4). accounted for 2% of the trawl catch in 1988 89. :; Over 75% of the anctovies were caught at Nil from . August through October. Because anchovies typical. Seine monitoring ly have a spatially patchy distribution, their catches . in trawls were highly variable. Annual totals ranged Forty-onc fish taxa have been caught in seines from ' from more than 10,000 in 1985-86 to less than 300 ' June 1976 through May 1989 (Appendices IV and V). in 1987 88, Like the windowpane, skates are also a More than 75% of all of the shore-zone fish captured resident demersal fishes found mostly (67%) at 1T were collected at JC, a productive nursery area. > and BR, The 1988 89 percentage. contribution of nroughout the 13-year monitoring period, juvenile skates to the catch was 7%,'a proportion similar to silversides dominated the seine catches during the sum-those foimd each year of the 13-year series. Silver- mer months (June through September) and, together sides, accounting for 3% of the trawl catch in with the adults accounted for 83% of the total catch. 1988 89, were found primarily from October through In 1988 89, only 62% of all fish caught by seine February More butterfish (Peptilus tricanthus) were were silversides because mummichog and striped 5 caught in trawls in 1988 89 than for all of the killifish (Fundulus spp ) were more abundamt in 1988- ; preceding 12 years combiacd. Both northern pipefish 89 than in any previous year, and accounted for 32% . (Syngnathusfuscus) and rock gunnell (Pholis gunnel- of the total catch. Most (75%) of the mummichog ; lus) were more abundant in 1988 89 than in any of and striped killifish were also caught at JC Silver-the preceding 12 years. After an 8 year decline, trawl sides were selected as a potentially impacted taxon - ) catches of cunner increased in 1988 89.- because of their dominance in the shore zone of Jor- :t dan Cove, an area periodically'affected by the ' [ Annual variations in the abundance of the six three-unit cooling water discharge and will be dis. dominant trawl taxa were evaluated by ext ming yearly cussed in a later section. [ 1 [ i ! I TAllt.li 4. %e 6 mean* canh (noJ0.69 km) of the most abundant fuh collected by trawl for each report year during June 1976 through May I 1989. Tunn 76.77 77.78 7R 79 79 8D 80 R1 81 82 12.33 R3 84 E4 85 R516 ' 86.R7 87 89 RB.89 , Psamiopleuroneesss americanus 16.6 13.5 16.7 26.8 - 32.6 24 1 41.8 27.7- 29.5 22.0 19.8 19.3 26.2 i Stenpromu chrysops 10.6 19.8 13.3 18.5 17.0 - 20.4 27.5 26.6 22.3 ~ 13.6' 30.6'- 21.7 18.0 Anchoa upp. 11.1 3.3 39.3 0.1 0.1 4.0 0.2 0.4 - 0.7 .113.8 57.3 1.6 3.1 J > ScophsAalmus aguaeu 2.9 2.4 18 2.9 3.5 2.9 6.7 . 5.0 4.4 ' 4.7 3.8 4.0 5.1 Ra spp. 1.4 1.2 0.8 0.8 2.0 1.4 6.1 5.3 3.1 8.5 - 4.5 4.6 6.3 : Areautia spp. 16.2 9.7 2.8 6.2 6.5 1.8 . 1.5 2.1 0.5 1.9,_17.5 2.3 . 3.4 .;
- Data seasonally restricted to June October for Stenosomus eArysops, to Ausust. October for Anchoo spp., to October. February for Menidia l spp., and remaining taxa year round (June.May). '
L 88 Monitoring Studies,1989
Entrainment Estimates ! TABLE 5. Tasonomic composition of ichthyoplankton col. Early life history mortality las are among tha fh sh M 1 89 [ most critical factors influencing adult fish stock i abundance (Cushing and llarris 1973; Bannister et al. im u rvar r n .,,_ 1974; Cushing 1974; hiny 1974; DeAngelis et al. Aachoa 'PP- 59 8 81 1977), Thus, an increase in mortality precipitated by l I""d"P 'u'0*'tk8 8"i,rkanus 11.4 0.0 entrainment losses at hiNPS could affect local fish populations, From June 1976 through hiny 1989,
^
f ',,O,PP;,nacae j , [6 j 's raoti, ,uan,fic 2.2 0.0 , eggs of the cunner, tautog and anchovies accounted Bravoortia tyra*aw . 1,7 0.0 r for over 90% of all eggs collected at EN and 85% of Ta"'orola6'* ad'r"'* l6 33 7 the larvac entrained were anchovies, winter flounder, Ia"soga omiti, 1.6 30.6 sand lance, and grubby (Table 5), Annual entrain- $',I[h,,,,,, d l$ ment estimates for these taxa and the volume of syngaa,Aufwce 1.0 0.0 cooling water used to calculate these estimates are EacA,1 pore cimbrie 1.0 0.7 presented in Tables 6 and 7. Entrainment estimates Stork'hal** afuosus 07 2.7 were calculated by multiplying the median density at I'Pr triacanthus g Oj EN times the total volume of cooling water that p,;,,,,,, ,pp, o,3 3,7 passed through hiNPS during the season when 95% Afyoaoc,praiu, acrod,ce,crinose 0.2 0.0 of the annual cumulative abundance occurred. After Sienosomai cArysops 0.2 0.8 Unit 3 became operational the cooling water volume Cl+ra ha"agw - 0.2 0.0 used at hiNPS approximately doubled, so that, in C)"*** 'tralis 0.2 0.1 most cases the cooling water volume used in cal-culating entrainment estimates also doubled, Because
#',[fj,#'"*,"'
3, 3 , , , , h Uj. Aaruitta rostrata 0.1 0.0 plant operation and the annual larval season for each - Atenidia spp. 0.1 0.1 species varies, depending on the time of spawning and . Alosa spp. 0.0 0.6 larval development, the cooling water volume used to ll'#rh7'i' 'PP- - 0.0 0.4 I calculate the entrainment estimates varied. For ex- ,O*, ,pp. lj ample, anchovy eggs were only present in LIS for a [2 asa,a p,,uaona,,agm 0.0 0. i short period of time in 1988, which accounted for a lower cooling water volume used in the entrainment TADt.E 6. Estimated annual number (x10') of cunner, tautog, and anchovy eggs entrained (with 95% confidence intervals) and the annual vohane of cooling wster (a10 6m 3
)on which the entrainment estimates are based.
Cunner .Tautcg Anchosv 6 6 Year Na entrained (X10 ) Volume' Na entrained (X10 ) Volume' No. entrained (X106) ' Volume
- 2 (95% CI) m X 10' (95% Cl) m' X 10' (95% CI) m5 X 10' 1979 1,675 (1,342 1,964) 245, 646 (508 810) 351 464 (366 540) 273 1980 2,032 (1,654-2,972) 233- 992 (836-1,158) 308 183 (47 250) ' 204 1981 1,610 (1,335 2,145) 272.. 1,385 (1,201 1,655). 428 369 (285 462) 277 1982 2,103 (1,693 2,904) 305 1,443 (1,181 1,579) 462 214 (148-277) 226 1983 2,589 (1,763 3,088) . 218 954 O !9 1,275) 364 503 (348-700) 161 1984 2,154.(1,564 2,595) 270 1,212 (916 1,543) 408 808 (388-1,250) - 168 1985 2,216 (1,416 3,083) 260 1,436 (1,037 2,416) 413 16 (0-54) 354 1986 1,812 (1,420 3,083) 835 3,163 (2,597-4,021) 915- 348 (143 533) 620 i .1987- 3,002 (2,390-4,504) 754 2.973 (2,141 4,234) 839 16 (0-63) 517 1988 3,961 (2,753 6,427). 785 2,587_(2,204 3,472)- 1,014 26 (0-56) 355 a Volume was determined from rAe number of power units (Terating and the number of days in a season, teth of which varied annually.
Fish Ecology Studies 89'
. , . , _ - _ .m.. - _ . . , , ..
c 1; n d O ~j i .
, TABt.E 7. Estimaiad annual number (al0*) of anchovy, winier flounder, American sand lance and smhby larvae entrained (with 95% ,
confidence intervals)and the annual vakre of cooling water (a10f m ) 8on which the entrainment estimat6s are based.M Otuksg - Ansigny Water Finimder Amancan hand lace 8 . - - Year No. entrained Volume' . No. entrained ' Volume
- No. enirmined ' . Wdume' 1 No ontreined Volumes
, (XIO*)1 m'X 106 ' (X10*)- m$X 106 (X10') > m8 X 108 ' (XtD')- ~ "m1 X10%
(95% CI) - (95% C) (95% C) ~( 95% Q),
~
1976 448 (334 3 76) 327 ' 95 (68-113) 300 19 (15 23) - .575 , 12 (10-t5) ~ 330 1977 162 (119 4 48) 317 20 (24 40) 229 67 (57 77) 681 30 (25 34) . '336'
.1978 100 (112 237) 322 '58 (43 70)' 333 36 (22 49) 312 9 O 11)= . 1 242L 1979 601 (433 766) 294 37.(28 44) 203 62 (52 76) 615 . 4
/20 (18 22) : 323 =
1980 558 (481 707) - 267 41 (Il4164)' 349 67 (58 84) .713' 30 (26 37) - ;490!.
-1981 1,284 (1,061 1.532) 281 47 (34 62) ~ 170 57 (50 67). . : 390.. _45 (33 52)' ' M9.
1982 300 (230 3 % ) 349 127(102148) 345 .12 (1016) ~ 5444 46 (42-57); - 393 -i ~ 1983 486 (346 478) 303 172(111221) . 351 ' 20 (14 27) 632. .50 (42 63)" L 4031 + 1984 91 (59 159) 332 . 90 (52-110)- 243 13 (10 16)'- 643' .36 (29 43): .396' 1985 455 (376 750) 391 66 (49 94) J308 6 (5 9)- . 5 4 5 -> 36 (29 42) ;283a ' 1986 238 01 399) 326 109 (85 139)' 581 .3(05)3 1081- 47 (3841) J714' 1987 57 (36 124) 359 126 (93 154) 710 20(1345) 1 954 46 (32 59) - 789* 1988 350 (191 446) 643 ' 138 (95 218) 802 >65(5t77) =1058, .142 (110 177) 6801 1989 _....h . . , 131 (102 180) - 396 13 (11 29) - :1142; . 82 (69 91).' ,644- c
- Volume was determined f rom the number of power units operanng and t'he numhet of days in a season, both of which varied annually. -
b NN calculated because larvae occur after end of report period (May 1989).1 estimate for that year. Furthermore,lf one or more of ~ cunner and tautog eggs were the dominant egg taxa the MNPS Units are out of service when a particular entrained! Silversides were also selected because they - taxon occurs, then the cooling water volume used to dominated the shore zone in Jordan Cove, which may > calculate an entrainment estimate is lower, as in the . be thermally impacted by the condenser cooling water - case of winter flounder larvac in 1989, discharge (NUSCO 1988b) These six taxa have been selected in the past (NUSCO'1987,1988b, ly89),L Entrainment estimates for cunner and tautog eggs . and are describedin detailbelow.j -.
" 1 increased along with cooling-water volume. Larval
- grubby entrainment estimates for 1987 88 were nearly ?Arnerican saiid lance three times greater and 1988 89 estimates were two: . .
times greater than previous estimates. This increase De American sand lance is a schooling fish comi, was probably related to both the increased density of . mon in estuaries, along the' coast'andzin_ offshore : grubby larvac (soc Table 2) and the increased t ooling waters,3 Found from the.Arct.c i to Cape Hatteras water volume. . (Bigelow and Schroeder 1953), the American sandi lance feeds primarily on plankton, lives .of 5 to 9i Selected Taxa years, and spawns between: December and . March; .
. (Richards 1963,1982: Leim and Scott 1966; Westin3 The selection of potentially impacted taxa for . et all19791 Grossicin and Azarovitz 1982p Arotmd
. further discussion was based on their prevalence in MNPS, sand lance are caught predominantly as larvae i entrainment samples or their susceptibility to thermal
~
in the. winter and spring.4 Sand lance are seldom ( impacts. Using these criteria, seven taxa were con- . caught in trawl and seine nets, perhaps because they ? sidered for further analysis. Because the winter floun- burrow into the sand (Leim-and' Scott 1966) S Few? der has been studied extensively,it is discussed in a eggs 'are collected because they are demersall ~and[ separate secilon (see Winter Flounder Studies), adhesive (Frizsche' 1978), i Yearly entreinment es-Larvae of anchovies, American sand lance and grubby : timates ranged from'3 to 67 million larvac (see Tabic! H were abundant in entrainment samples and anchovy, 7)c
>90 Monitoring Studies,1989 <
i f t p . #,. g (~, .
.2b
Sand lance larvac were typically collected near TABLE s. The 6 rneans density (noJ500 mb) and 95% conti. MNPS from December through 13ay. Annual dates dence intervals of American sand lance larvae collected at t'N of peak abundance ranged from January 16 to May 30, and ND for each report year during June 1976 through May I'8E varbd among the years and between EN to NB within a year. The running 6-mean of 8,arval density was y,,r a Nn compared to the annual 6 mean of larval density to determine abundance trends and annual variation (Fig. 1976 77 941 17 4). Annual 6 mean densities varied an order of mag- 1977 78 3181117 nitude from the late 1970's to the mid 1980's. Be- llQ,7' i go [z,s 1 j g 3 , ,, cause sand lance larvac were so abundant in the mid to 1980.s 1362 32 238 2 106 late 1970's and early 1980s, the long-term trend since 19si.s2 211 4 201 6 198182 is downward and,except for 1987 88 at NB, 1982 83 2718 542 23 all the annual 6 mean densities since 198182 were 1983 84 18 1 d $81 30 below the running 6-mean. Ahhough the 1988 89 6- f,$8s g, si mean density was also below the runnmg 6 mean 1986 s1 131 4 132 6 estimate,it was the second highest of the last 8 years 1987.ss 41 1 13 631 44 (Fig. 4; Table 8). It is not unusual for sand lance 1988-80 31 2 13 351 15 larvae to exhibit wide fluctuations. Monteleone et al.
- Data seasonally rcotricted to December . May.
4m, D (1987) enumerated sand lance larvae from over 2,000 e i ichthyoplankton samples collected during 17 years two eurr g, ,. onaamsonj nmm.ewrr ATios spanning the period from 1951 through 1983 and 6 ji i found that larval sand lance densities in LIS exhibited 6 l\ l fluctuations of two orders of magnitude during that 20' h l \ period. m : . i.
'" \
- m. ! To examine interannual variability of sand lance hi
;0
\ '
larval abundance, !arval densities were regressed against average MNPS monthly water temperatures vs77 ' tit, s6ai ' s2 3 ' siis ' is 7 ' as ' from December through May. Results indicated that 68% of the annual variation in density was explained g by March water temperatures (r:=0.68; p<0.001) 4m. i (Fig. 5). Colder March water temperatures generally
'i m>curr8 ' nu usrr resulted in higher larval densities, the highest den-g, on2 Ams , on nanoN i
sities of the 13 year time series and the lowest g temperatures occurred in 1977 78. Sand lance larvac g *'" / l have evolved to survive prolonged periods without
;x / ;' I feeding, up to 60 days at O'C (Monteleone et al.
$ , l 1987). Thus, colder water temperatures would be x im- *"
i I , advantageous to sand lance larvae allowing them to l4 * *
-o-i ,. * " '.,
e s ,i....
, . ' ,'3 survive until the spring plankton bloom in LIS.
0 7sn 7(79 ' assi ' s2: 3 ' sei3 ' ass? its: 9 RFPORT YrAR MM hh a mmM h M M W larval catches along the Northeast Atlantic coast has displayed radical shifts during recciit decades. Meyer Fig. 4. The annual ( --) and running (-) 6.mean density et al. (1979) reported that the average trawl catch of (no/$00 m3) of American sand lance larvae at EN and adults in the spring in an area north of Cape Cod NB. during the 1967 75 period was near 0, increased to 50 in 1976, and exceeded 10,000 in 1977. Although few Fish Ecology Studies 91 j l l _____ . . . . . ..____.m
o, , z , y E sand lance are caoght in trawls at Millstone, their; collocuons at EN and NB and its eggs were the third = abundance fluctuated from year to year (Appendix 11). . most abundant (see Table $). More than 50% of the
- As . described previously, the density of larval sN1 ? eggs collected armually were found during a 2 to lance in_ the MNPS area and throughout L1S 3 week pened in summer. Kuntz (1914) reparte:I that
. (Monteleone et al.'1987) also exhibit large annual at 27'C, anchovy eggs hatch in about 24 hours; The fluctuationsJ Given the dramatic changes;in . annual dates of peak egg abundance ranged from late
- s' alwndance of this species, effects of MNPS operation June to mid July and the dates of peak larval abim.
on aand lance may be difficult to ascertain, dance ranged frorn mid July through mid-August-Annual entrainment estimates ranged from 16 to 808 ' million eggs.(see Table 6) and from 57 to 1,284 - million larvae (see Table 7). The 6 monn density of - anchovy eggs at EN in 1988 was the lowest in the 10 : i . year series (Table 9). ' Although the 1988 8.mean larval densities were higher than those in 1987., don-5 **' sitics were still low and comparable to the lowest. densities in the series. De running 6-mean oflarval : hy densities at EN and NB peaked in 1981 (Fig. 6), and g *y zo.' all the annual 6 mean densitics since then have been:
,I ; A* below the running 8 mean. Juvenile anchovies, resul.-
.,d p ,
*.,j
- ting from the summer spawn, are typically captured 1 in trawls from August through October, pre <kiminant.
e onm . D i i j -f ;, ly at NB (Appendix 111). Even though anchovies 8
~ MAkCil WA11R1EMPIRA1URE('t'.) trawl, their annual catches were highly variabic and .
Fig. $. Linear seletionship betwocn the annual 6-mean more than 75% of them, were caught in only 2 years,1 density (nof$oO ml) of American sand lance at EN and - 1985 86,1986 87 of the 13.ycar scrics (Appendix II). March water temperatures (ac) at MNPS from 1976-77
- tough 1988 89.
TAH1,8 9, lhe 64ncan' density (noJ500 mI ) and 9$4tunfo
- dence intervals of anchovy eggs and tarvae collected at EN and Anchovies NH for each report year during June 1976 through May 1989.
De bay anchovy is perhaps the most common fisti 10 05 LARVAE-along the Atlantic coast (McHugh 1977). Both the-bay anchovy and the striped anchovy are found in the =1976 1152 i 419-Millstone area, but the bay ~ anchovy 'isL most -1977 931 240s L , numerous (>80% ) of the two species, and, thus, the 1978: . 43 4206 casuing discussion will center on the toy anchovy.
-The bay anchovy ranges from Cape Cod to Mexico,
. Q y j36 ,
68 2
,9 3 s 1981 10s0 1 264 5%: 2334 7873 1 9799' but it can occur as far nonh as Maine (Hildebrand 1982 - 765222:. 8164240 2103 1 1358 i
- 19431 Bigelow and Schroeder 1953); It is typically -
~
1983' 2257 x 1076 1421 a530 .2860 1 2112 !
-l the principal'ichthyoplankton species in estuaries t984 4sso 13680 3024165 327 1254' !
within its range (McHugh 1977; Leak and Houde =l'85: l'82 75 H021"3 .
- )i171575 = j
$g[ 2 2 On
~
1224 j
.1987).1 The bay anchovy is typically inshore during
}
. warmer' months and: moves offshore in winter 1988 37 23-3 .359 a216E 303 1257 - g i
. (Oressicin and Ararovitz 1982). .l i
. Both anchovy eggs and larvac were dominant in ' D* aonally r**uicied to June 15 i August 5 for eggs, and .- l
- ichthyopicnkton shmples and juveniles were abundant 3"lY # S'P"*b I"' l*''-
+ lin trawlse Anchovy larvae dominated plankton .l a l ! 92 ; Monitoring Studies,1989 ' j j n o j= i
i EGGS AT EN . also observed in LIS from 1952 to 1955 (Richards J gggigggy [ 1959) and in Barnegat Day, NJ from 1976 to 1981,- (Vouglitois et al.1987). It is likely that these large 4 mm ' interannual fluctuations m abundance are the result of 8 '
, ! cvents that take place outside the Millstone area 2: ji l during the winter migration of bay enchovies. Fac-l
[ ,, /i i tors controlling the migration of anchovies are not 5 / iI well understood, and neither rates of survival during k ** % the winter nor whether anchovies return to their natal I; ~~'W i. ,,,b.,- estuary are known (Voug0tois et al.1987). , In 1988, the &-mean dernity of anchovy larvae was low and egg densities were the lowest yet observed LAkVAE AT EN (Table 9). The abundance of eggs (a measure of i e l spawning stock size) and resu'tirig larvae should bc { ** gggjgggy correlated if density dependant. To investigate this a - o 3 , larval recruitment index was calculated as the log-6 !) I arithem of the ratio of the 6-mean oflarvae collected ' . hae /k l i in August to the S-mean value for eggs (Ricker g *
/ i 1975) and compared to the S-mean for eggs, The use i l of larval abundance in August provided an index of f; ~
g ,, ,,' *,, , j ., - late-larval or pre-juvenile recruitmen;. A significant (p<0.001) negative slope was found suggesting com- ,
"75 . s (9 ii 6 6 (7 6 pensatory mortality similar to that reported in idCO (1988c and 1989) (Fig. 7). Therefore, in 1 * ', the lowest egg abundance produced the highest LARVAE AT Nn
,, g IrWal recruitment index or survival. Vouglitois el al.
/t (1987) found a similar relationship for bay anchovy .
fo ** /
/k ENElii EElrE in Barnegat Bay, NJ during a 2 year period. Com-pensatory mortality of bay anchovy larvae can be f
t;; or
/
i i j i produced by several factors, including starvation and predatory pressure (Houde 1977,'1978a,1978b; Leak l l33 6-i ,,., 4' i, i and Houde 1987). Compensatory mortality during the . l ectly life history of anchovies could help mitigate
@ w tw. "
',...l*
, entrainment losses in the MNPS area.
4 o 75 71 79 81 83
.' 'r * .
85 87 89 i 3, l YEAR 8 ' as 21 2', 3 Fig. 6. The annual (--) and running (-) 6 mean density p p , (no./500 m3)of anchovy eggs at EN and larvae at EN and d s7 ,'",, NB. h o<- g g , . 5 .t W Anchovies mature within a few months of hatching d and live only I or 2 years (Stevenson 1958) and 3 0.'o.9:5 u short lived species usually exhibit large abundance P < 0.001 a ascillations. Large annual fluctuations exist in our o '1000 2000 3000 4000 5 coo anchovy egg data; the 1983 and 1984 6-mean egg 3 5.MEAN Eco DINSITY (No./500m ) f
'lensities were so high that they were the only 2 years F g. 7. Linear relationship between larval anchovy above the running 6 mean density (Fig. 6). Large recruitment index and the 6-mean density of eggs.
6.mual changes in bay anchovy egg abundance were Fish Ecology Studies 93
'i SilversidCS TABt.E th " Die &mean* catch (noJ30 m) and 95% confidence : 1' interval of silversides collected by seine for each report year '
Along the Connecticut coast, the Atlantic silverside during June 1976 through May 1989. , and the inland silverside are among the most common year Jc GN WP shore-zone species, The Atlantic silverside ranges 19766 ! from the Gulf of St. Lawrence to the Chesapeake Ba 1977 1251 1 2094 151 1 569 62 1 168 ! and the inland silverside from Cape Cod to South 1978 262 20 '32 2 M 242 35 ' Carolina (Johnson 1975). Both species are important 1979- 411 55 >262 27.- 151 12 :l forage fish, spawn as yearlings, and live from 1 to 2 _ 1980 497 i 930 . IM i6 9 55270 years (Bigelow and Schroeder 1953; Beck and Poston 1980).' Because they were not always identified to 3l$ 3983 [t $ 5801 989=
$2 72 312 421 591 19N b1 112 1 158 species in MNPS programs, the_ two species were 1984 35235 1139, 33I analyzed as a single taxon to determine long term 1985- -232 14 181 11 614 ,
r trends. Ilowever, in instances when identified, over _ 1987 1141 92 : out 48 642M 1988 125 t 132 522 28 361 23 90% were Atlantic silverside.
~
The annual 6 mean catch of silversides in trawls a p,i, seasonally restricted to June-November at all stations. r and seines varied by an order of magnitude, which is b Not enough daia available in 1976 to calculate 6-mean.
. typical of short lived species. The 1988 89 6-mean q catches of silversides in trawls and in seines were within the range of previous catches (Tables 10 and 11). The running 6-mean of trawled silversides has a Juvenile silversides dominated the inshore seine downward trend which began in the late 1970's and collections in summer and early fall (July October)~'
carly 1980's and has continued during three unit and adults were taken by trawls during the late fall and '-
. operation at JC, IN and NB (Fig. 8).' Silverside w nier (November. March)/ This pattern suggested catches at NR have increased since the startup of Unit that adults in the MNPS area overwintered in deeper -
3 and 1986-87 had an extremely high 6-mean catch. waters close to shorel To determine if there was a During the late 1980's the running 6 mean of silver' change in the length frequency distribution after Unit sides taken by seines have remained relatively stable' 3 became operational,,the length frequencies, as (Fig. 9), percentages (length frettuency totaled 100% for each period) for the periods before and after three unit operation were examined. The length frequency TABLE 10. The &mean* catch (noJ0.69 km) and 95% confi* distribution for both trawl and seine silversides has dence interval of silversides collected by trawl at selected sta-remained similar during two-unit and three unit opera-tions for each report year during June 1976 through May 1989. Report vcar IN JC Nn NR__ _
~
1976 77 15 116 131 20' 61 8 77 2 283 The relationship between summer water temp-1977 78 29 129 61 612. 181 25 10 121 cratures and the annual 6-mean catches was investi-5 28 8 7 - 2 sI gated to examine the interannual variability of seine-Q79 gg g 9_, 2 , caught silversides. A significant positive relationship 1980 81 8117.4 4 x 4.6 _ 19 2 41.5 3 z 3.8 1981 82 619.2- 0.720.4 52 6.4- 628: (p< 0.001) was found to exist between the catch of 1 1982 83 213.5 12 2.4 -03 1 12.5 1214 7 silversides at JC and July water temperatures (Fig. 1983 84 214.2 di 1.3 42 0.6 116.3 11),- but no significant relationship was found~for catches at GN and WP, JC is a productive nursery 6 6$ i .4 3I 9 area and most of the silverside catch at that site is 1986-87 513.1 81 6.9 1 t 2.9 110 1222 1987 88 3146 -22 1.6 ', 4.0 15 1 27 comprised of young-of the-year. Warm' water - 1988 89 .2310.8 ' t.210.4 1.22 0.4 25 1 14.2 temperatures lead to quicker hatching and growth (Hildebrand 1922). This situation may be advan-tageous because larger fish may be less susceptible to -
- Data seasonally restricted to November-February at IN, NB and predMors.
NR, and October January at JCJ 94 Monitoring Studies,1989
i l t i-i r i. TW4UNTT 8 VIR11 UNIT lj0a Wi AA110N l OPIA ATK)N 100- .' E q g I fk 1wSUNrr ITIRILUNTT g o 80- I : = WERADONIOPIRAVON
& l !.
E t. p, IW-f so. . I . < g r a x ..' \, l l: :\. i. E
- n. \, \
i If
. I h: 2n=
i . . . . . . . . . . . .. .- . s e. ' ' . y 6 a- <
- t.
i l 0 ~ 1677 ' 7679 ' Wist ' 82 83 ' 84-83 ' 86 87 ' 88-89 g. ., l s : m-*4. 6 -
- n..c . w.
p , I, ,
~ TWOUNrT 9 T14REE UNTT 76 73 g) 32,_ $4 86 $$
$0a UPI AATION l OPIA ATION l,m- l -
I u E i '. l 2*' w F, p e- ./ '\ l iwnuNrr lustseNrr OPERATION 10PliRAT10N l B 6- ' i . l l g x 2o.
\ i E imi l t
8 . i 4 ****..........(l*......
~ ~
5 h
- g. I, ,.,' 1 7677 ' 18 79 ' 80 81 ' 82 83 ' M I55 ' 8647 ' 88-49 $ /
*6 : . I
/. m . .- / . le "
- __..
$ M \ / '. .
TWOUNTT I TifRFEUNrt x b..J ., 20 OPI' RATION l OPER ATION .6 .,,4
/ ll t i i f* ' ' '
fi [I 1 76 7'8 m) 8'2 8'4 8'6 - 8'8 . l, I E 10' l\
- \ m
' :* 1 l
\ : ; O 2
6 8' Q 2m, .- . iwouNrr InarruNrr
'b x '!
i 3,.,e . . s .
- e ,mua -.- lI WERATMlWERA1M I
4 'g' '.,e*. 've g k 150 RUNNINO ======
] 'e, l 7577 ' 78'79 ' ikist ' 82:83 ' 84 85 ' 8687 ' 88 89 / h .f 't6 1
R imi ! - i.- l TWOUNrT a TifRILUNIT '. 20 3 e _n OPERATION l OPER ATION 72 , l , 0 *. . ,
^-
l Q 2- ., .... I ,' - l%
<mpa "" y .
, )
g ie*.*. a is.___ , 4 .- Q & l 0 . . - - I. . < 6 . l 76 78 m 82 M $6 , 88 to' YliAR h '., ,.
,r*...l ' .~
6 . g.. .._ g 3 1 . Fig. 9. The annual (-..) and running (--) 6-mean catch 4 '...<* i %.. (nO./30 m) of silversides taken by seine at JC. GN and 0 ,g,g 7g77 7,79 82 51 ' 84-85 ' 8s87 ' 88J89 WF. RfiPORT YEAR Fig. 8. The armual( -) and running (-) 6 mean catch (no./0.69 km) of silversides taken by trawl at NB. IN. NR and JC. Fish rcology Studies 95
' Because the thermal effluent from three-unit opera- t
- st2Nt! os tion has been shown to encompass Jordan Cove E E S $rtl$^n"Anos (NUSCO 1988b) the potential exists for changes in 3 - abundance and seasonal distribution of silversides 1 inhabiting the shore-zone at JC and WP. Sampling !
fj i frequency during April through October at these two - '
.20' Q E -
! sites and at the control station, GN, was increased to .,
f 10' [ [ b M i
, , biweekly in 1984 to improve the ability to detect changes. Therefore, monthly silverside abundance ;
g 7 Q g y = from June through October was examined from 1984 -
^
o 4 f""7"'I through 1988 to determine if changes in abundance 2po 41 60 6140 81 100 101120 - >l20 and seasonal distribution patterns have occurred during the three unit operation period (Fig.12). Initially, one would conclude that the ubundance of silversides ;
# TRAY't-g gp pgAg at all three stations had increased during three unit operauon, but the abundance of silversides was at an g* -
historical low in 1984 and 1985 and now it simply . h has returned to abundance levels that were common
- fp . prior to 1984 (Table 111 Appendix IV)c.While the y
~
t- 20, season of occurrence for silversides has remained , h J stable during two unit and three unit operation, the g in , monthly distribution during its season of occurrence 1 ' varied from year to year, llowever, there was no clear change -in distribution after Unit 3 became o 20-.to 41 60 - 61 80 81 100 101 120 >t20 - operatio..al, Distribution patterns seem to be more . Isnl s milar among stations within a year than among Fig.10. The percent length-frequency distribution, by 20 mm intervals, of silversides from seines and trawl years at a given station. collections petitioned into two unit (June 19764's 1986) and three unit (June 1986-May 1989) operat'+..! Grubby periods. . .- Found primarily-in celgrass habitats along the Atlantic coast of North America from the Gulf of St. Lawrence to New Jersey,- (Bigelow and Schroeder g 1953), the grubby is a resident fish in the Millstone N# area.' It is a winter spawner (Lund and Marcy 1975) D ,: . c oo
- y and larvae are found from February to April in shal-P < 0 ml lower areas of LIS (Richards 1959). Grubby eggs are h#' rarely collected, probably because they are demersal h
6 . and adhesive (Lund and Marcy 1975), but larvae are abundant in ichthyoplankton collections.
^
5e . h -g ,, ', '* Larval grubby accounted for over 4% of all larvae collected at EN from June 1976 through May 1989 E 20 i2 $ i6 is N i2 - (see Table 5) and annual entrainment estimates ranged JULY WA'lliR TiiMP1 RATtmi!(*C) ATJC collected at both EN and NB, primarily during: Fig.11. Linear relationship between the annual 5 mean February through May, and the dates of peak abun-catch of silversides at JC (no/30 m) and the July water dance varied froni mid-March to early April. The temperatures (*C) at station JC from 1976 through 1988. 1989 enttainment estimate (82 million) was the second highest of the 13-year series. This increase ; can be attributed to both an increase in cooling water volumes due to three-unit operation and also to higher 96 Monitoring Studies,1989
i [y@y'"g'T, K ",N7$w" ' TABLE 12, 'the 6.rnean' density (no./500 m 3) and 95% conri- *
***, ~
l dence intervals of grubby larvae collected at EN and NB for each j report year during June 1976 through May 1989. yne. -e Year 13 NB l 1977 4119 muc. j 1978 38 39 l 1979 3617 l - 1980 38 47 31112 [ W'**' ,. .
~
- 1981 107 2 27 54 1 30 l
1982 72113 28 a13 o ri. - rO b b 1983 68119 39 118 , nuwru 67 8 910 61:9 o 61s910 67:910 6 7 s 9 to 1984 50215 24 113 '[ 1985 68323 18 310. 1986- 34 410 26 211 ; twnt'Nrr g utRILUNTr l9$7 29 g7 28 g 18 (wi nATicw g ort.kATioN gio .
~
1988 95 1 35 119 166 1989 63 118 44 218 g l - u un.
": l 1
.c ern. ,
- a Data seasonally restricted to February May, D ,
g ... N -
~
l ." g ,. B TWo.UhTr 'TilRrh0NTr F- OrtAATIONIONRAT10N
-e- , . r-12' I o _ _ ,
I huwin 61 s e io 6 ? s e to 61s e to 67s910 61:910 e 9 l g 100- ! ,. , 4 R ! ,* I rwauNn OPWTHW a umrseNrr ONRAHON R so-
! ,',,** l !
;\
y, . g l ,
, ,8, l g
h- . k
,d a- r . . . . . ,!
, , , . .i g "
g 20- I wo. ,, g.
*o- . i -
76 7's si) s'2 s'. - 86 s's 9i) s d n. I - -
); - . -
iwausrr auma uorr F l OPERATIONIOITRATION
, rT- t _r l le ,- r ,
12- I ,t . I MoNTn 61s e to 61s 9 to 67s910 61 s 9 to 678910 E '! I . e 100- I *i i YllAR R4 . s 5 s3 86 so s1 87. ss as.s9 f l ! g so-l lt'g Fig.12. Total monthly (June September) abundance of C 60-
/**,
l fi silversides taken by seine at JC, GN and WP (1984- I I, x I.... 2 1 awwo- i larval densities (see Tables 2 and 3). Except for o . . . . . . . 76 1s s2 - p 86 u w 1988, larval S-mean densities have been fairly stable YEAR at NB. Flowever, at EN larger annual fluctuations occurred especially during the 1980's (Table 12). The larval grubby was de of the few taxa exhibiting an Fig.13. The annual (---) and running (-) 5-mean density increasing trend (Fig.13). (no./500 m3) of grubby larvae at EN and NB. i l Fish Ecology Studies 97
t Caught primarily at the nearshore trawl stations (NR. IN, JC), Juveniles and adults were found- TA111.E 13 lhe 6.mean' catch (noJ0.69 krn) and 95% confi-throughout the year at JC and NR and during their deac' iat"v'l' of grubby collected by irewl ni selected stations spawning season at INi The 1988 89 6-mean indices for each rep et year during June 1976 through May 1989. were above the running 6 mean at both NR and IN n ,no,,ye,, ya je iy = l and below the running 6 mean at JC (Fig.14), bet all were within historical ranges (Table 13), 'Ihc percent 1976 77 0.91 0.3 0.61 0.2 0.6101 ; length frequency distributions (each period equals 1977-78 0.51 0.1 2.2 z 0.5 1.12 0.2 9 100%) of trawl caught grubby were similar before and alter three umts began operating (Rg.15)- 1980-81 3jz $ 3.8 z I.1 1.120.2 y6 0;7ioj 2.11 0.6 1981 82 7.5 .4 2.5 1.01 0.2 -2.310.6 Twntwrr y9g2 83 11.71 2.7 1.41 0.2 2.21 0.5-12- ,"#^** ,l inntLUNrr WRAMN 1983 84 4.11 0.8 1.71 0.3 1.71 0.3 E
! I , 1964 85 5.911.2 1.61 0.3 0.910.2 g 10] /) l [ 1985 66 2.31 0.5 - 1.410.3- 0.71 c.)
N P ,, /i 1 ; ! 1986-87 7.21 2,3 1.11 0.2 0.91 u,2 - *
-6
/ k I i
e ./ 1987 88 371 32 12102 1.11 0.2 3 6 t ['., !- 1988 89 - 10.512.3- 1.01 0.1 1.41 0.3 s , ! \ /' I i !
~t 3 4, } _ Y \,O .(' & ~
a Data seasonally reuricted to December. June a' IN, and year-E 2- ;, h'.1[ round at JC and NR (June May). 4 ***f'** y 0 7677 ' 78:79 ' 8681 ' s2:s ' sss5 ' sss7 ' as.s9 1 TwoUNrr a 'nlRI.rv0Nrr 2.5 ' Orr. RATION l Ol'l*ATioN 30' l I ,., l " " " _ bNR I N I 20- ! e D- + t ! \ I g R ~"" r [ '* [ 5
,***,)
g 20' [ ~ g l \ - j- f .,y - g [ Q k _
'g io. ; iV .- i I
p y 9 c -- y f 10' % g h - 4 LC h
- 5
, e a n
76 77 ' 78 79 ' sost ' 82 18.1 ' ass $ 's6:s? 'sais9 0 ' 60 70 - 71 80 81 90 91 100 101 110 >l10 -I t.ENG111 iwouNrr i miuscNrr Fig.15. The percent length. frequency ' distribution, by 2.5 , e. orr*ATioN l oM3 AWN 10 mm intervals, of grubbies taken by trawl partitioned s I I wsuAt.**'* r . * * " 's into two. unit (June 1976.May 1986) and three-unit (June
$ 28- a,. o ! ',
l 1986 May 1989) operational periods, st . o .! s 6 1.5 - [
- I h I \., i to-a l. .
g ""
- i Both the abundance of larvae and adults and length.
x 13 l frequency distributions of adults have remained sim-4 0, e ilar throughout the 13-year data series. Although 76.n ' 7s:79 ' sosi ' s24i ' ass 5 ' 36:si ' ss a, ' larval entrainment increased with the start of Unit 3 REPORT YEAR cooling Water usage, no observable changes in abun- ; Fig.14. The annual ( --) and running (-) 6 mean catch dance levels occuned. (no/0.69 km) of grubby taken by trawl at NR. JC and IN. 3 98 Monitoring Studies,1989 i I
.l l
l Tautog EOGS AT EN
, xxxu -
i The tautog is a long lived species found from New , wuntrimsuurr ,i onarnosionnaw 11runswick to South Carolina (Cooper 1965). From - May through October, individuals reside in rocky near. $* ,, / il,.***, shore areas (lligelow and Schroeder 1953; Wheatland / '* ,, g 1956; Cooper 1965); juveniles also dwell among - 6 macroalgae (Tracy 1910; 11riggs and O' Conner 1971), In the winter, adults move to deeper water and remain a 2aw l l h I dormant, while juveniles overwinter in a torpid state *
*M l near shore (Cooper 1965; Olla et al,1974). Tautog s eggs are pelagic and hatch in 42 45 hours at 22'C 73 A gi 6 6 6 si (Williams 1967; Fritzsche 1978).
LARVAE ATEN 120- l Tautog eggs accounted for more than 30% of the 7 westrinian.usrr total eggs collected at EN, but larvac accounted for a im- w^wiwt*^w less than 2% of the total (see Table 5). 'Ihe dates of 4 , l peak egg abundance ranged from mid to late June $# /\ 1 Along with the increase in cooling water volume $ w / \, l during the three unit operational period, tautog egg entrainment estimates have increased (see Table 6). {* / 's , I
., / .,
The 1988 &-mean density of eggs at EN was lower 20- \ . '.
' I than the 10 year running 6 mean, but was within the 'd
; ,.. \.** ,' ' ,., a. *
- j historical range (Table 14 and Fig.16), The running 75 s s 6 6 6 6 si I S mean for tautog eggs had an upward trend since 1979. The S-mean densities of larvac were always higher at NB than at EN (Fig.16). Since 1984, larval I ARVAE AT NB
- m. ***
ip goo. .
* ;nsusrrInintsusrr !
,.* -' QNRATIONIONRATION k y..e l i
{g TAal E 14. He 5 mean' density (noJ500 m )3 and 95% confi. so-4lence intervals of tautog eggs and larvae collected til EN and NB j l
/ ;
for each report year during June 1976 through May 1989, # ' i m I 10GS LARVAE 6e ** . Year EN EN Nn h 20- ,m . . 1 . A . Ib.** 1976 37 16
- o " .~ . . . .
1977 36 117 75 71 79 81 83 85 87 89 1978 111 Yr.AR 1979 1364 1 231 1115 491 22 1980 2842 1 623 46 1 18 89 18 4 Fig.16. The annual (---) and running (-) 6-mean density 1981 2647 1434 83 1 36 91 160 (no./500 m3) of tautog eggs at EN and larvae at EN and 1982 2244 1 434 44 1 21 110 1 59 NB, 1983 2114 1 472 33 121 119 1122 j 1984 2157 1440 312 28 1 20 j 4 i 6 76f 3 2I6 densities have been declining to levels comparable to 1987 3011 1823 713 13 17 those in the late 1970s at EN. This decrease was j' 1988 2269 1600 17 1 to 29 1 11 similar to trends observed for other summer-spawned larvac, including anchovies and cunner. i
- Data seasonally restricted to May 23 August 20 for eggs,and June August forlarvae.
A low egg to larvae survival was found when ratios of larval to egg 6-mean densities at EN were ex-amined. Lanal densities were generally less than 2% Fish Ecology Studies 99
i of the corresponding egg densities. Low natural egg the DEP (NUSCO 1989). That comparison resulted ! survival, as is indicated by this comparison, would in a significant linear relationship (r2=0.81, p<0.05); ; mitigate egg entrainment impacts. This apparent low between NUEL CPUE and DEP CPUE. However, i' egg survi_ val is discussed further in the following when the 1989 DEP and NUEL CPUE data were cunner section.' included the relationship was not significant (r2=0.61, p>0.05).' The 1989 NUEL CPUE was the lowest of Annual 5-mean cittches for tautog in trawls could the 6 year series, while the DEP CPUE was higher t not be calculated because individuals were found too : than the previous 2 years (Table 15). The increase in infrequently (too many zero catches)._ Because trawl the DEP catches throughout LIS was due to higher sampi!ng effort was nearly the same cach year, the catches in the western end of LIS (P. Howell, pers. sums of the total catches at cach station were used.as comm.), Because of the random design of the survey, i indices of annual abundance (Table 15). These data t was not possible to correct this by separating the - were summarized by calendar years from January 1976 _. catch in the castern part of LIS from the total catch through December 1989 so they could be cc.npared to - (P, llowell, pers. comm.). -i other regional data. All 1989 catches were low espc. cially at the two offshore stations BR and TT, the BR Trawl-caught tautog length-frequency distributions? q catch was the lowest ever. before and after three unit operation _were prepared (Fig.17) and ages were assigned to length categories _ ' TAllt.E 15. Abundance indices for tautos collected by itsw!in based on necent age-lehg6 wod in W mpond by [ DEP8 random trawl survey and in the NUSCO b trawl monitonng Simpson (1989). Young-of the year recruits accounted + program. DEI" NUSCDh Year nR N JC Nn Nt,,,H,,'[gga[ 60' - 76 11 76 73. I8 46 27 25I b NEhtMNib.N > 77 27 70 113 37' 15 30 292 D 78 25 83 59 36 27 16 246 h - 45' 79 48 70 56 40 47 22 283 . p .i 80 10 46 20 23 25 14 138 t
~
3 81 25 28 24 25 126 7 235 _ 82 12 52 35 24 80 25 228 _ J - 83 29 - 40 19 23 31 17 159 15' kN - 84 764/200 tows (3.82) 21 46 16 14 5 8 110 h & ,,, 85 779/246 tows (3.17) 86 791/315 tows (2.51) 14 47 27 12 25 11 136 15 25 58 3 100 5 206- 0 q q ,,,,,,] 4 87 624/320 tows (1.95) 20 13 33 3 26 1 % LENOVI < 140 ' 140199 200 250 251300 301350 >351 - 88 630/320 iows (1.97) 4 37 31 14 50 10 146 AoE 1 U !!! IV V. ->V
][2 791/32n tows r2 471 0 25 23,,,,,H 38 2 102 p;g,17. ' The'percem length frequency dis 9ibution, by age (Simps (n 1989), of tautog taken by trawl partitioned
- Connecticut Department of Environmental Protection (DEP) into two-unit (June 19_76-May 1986) and three-unit (June random trawl survey for six :.reas in t.ong Island Sound.
1986 May 1989) operational periods. Ondeu annual sum of catches and number of tows (average caich per tow)) (P, llowell, pers, comm.), b Northeast Utilities (NUSCO) monitoring data fixed trawl survey for six stations in the Milhtone area (Fig.1) Ondex: for a high proportion of tautog caught after three-unit annual sum of catches (0.69.km tows)). operation began.. Prior to Unit 3 opcration,33% of - the tautog were collected at NR and JC.c However, in the Unit 3 operational period,65% were caught at The DEP began conducting a random trawl survey these two stations. Both stations are shallow water of LlS in 1984, in the previous annual monitoring - estuarine areas typically inhabitated by; juvenile report (NUSCO 1989), DEP catch-per tow (DEP tautog (Olla et al.1974). Older tautog (> age II. ) CPUE) of tautog from 1984 through 1988 were were found at the deeper water stations (IN,~ NB, BR compared to the average catch per tow (NUEL CPUE) and TT). During the pre Unit 3 operational period, of tautog at stations NB, TT, and BR, where. habitat 58% of the tautog were found at these deeper water. types were similar to habitats at stations trawled by stations, but only 34% were caught there during the i 100 Monitoring Studies,1989
i 3
~
-[
three unit operational period. Removal of the Unit 3 primarily from June through August, and juveniles coffer dam in 1983 probably accounted for the reduc. and adults were caught at all six trawl stations, most-tion of tautog at IN, because it had created an artificial - ly from spring through fall. Eggs are abundant at EN embayment that probably attracted reef dwelling from May through July and peaked annually during ' tautog while it was in place. The reason for the the first half of June. Larvae occur from mid June to - reduction in tautog at NB, BR and 7T is not readily mid-July, apparent. Smith et al. (1989) reported a large increase in the commercial catch of tautog in LIS in recent Egg entrainment estimates ranged from 1,610. F years (1980-1985), and Simpson (1989) reported a million in 1981 to 3,961 million in 1988 (see Table large increase in the recreational catch of tautog from 6). The increase in entrainment in 1988 can be' > 196(Ts to the 1980's and a two fold increase in the partially attributed to the additional cooling water - ! commercial catch in LIS from 1985 through 1987c demands of Unit 3. The running 6-mean for cunner The minimum size for keeping tautog in Connecticut eggs and larvac collected at EN remained relatively k is 305 mm, so the increase in commerical catches stable over the period, but the running 6--mean of should not have affected tautog in the 200 to 300 mm -larvae collected at NB had a downward trend that length groups, where the greatest proportional began in 1984 (Table 16 and Fig.18).' The S-mean - decreasc occurred. densities of cunner larvac at both EN and NB ' increased in 1988 when compared to 1986, and 1987 Although tautog larvac and adults have declined in densities, but were still among the lowest noted abundance during the 1980's, egg abundance, our best during the entire monitoring period. Larval densities - measure of stock reproductive capacity for this taxon, were consistently higher at NB than at EN throughout has increased. Egg entrainment has increased along the past 10 years, in 1984, larval abundance began - with the increase in cooling water volume during the declining and has not yet returned to the generally three-unit operational period, but egg densities have high levels found in the early 1980's. Ilowever, a= not declined. If entrainment losses were affecting similar large decrease in larval abundance at EN from
- recruitment, juvenile abundance would be expected to 1978 to 1980 was followed by an increase to relative-fall and result in a rise in the relative abundance of _ ly high numbers in the early 1980's.
older fish. Since an increase in the percentage of ) juvenile fish was detected during the three unit opera-tional period, changes in juvenile and adult abundance were pmbably not related to entrainment losses . Taut.E 16. 'Ihc 8-mean idensity (noJ500 m 3) and 95% confi. dence intervals of cunner eggs and larvac collected at EN and NB Cunner for each report year during June 1976 through May 1989. - Found from northern Newfoundland to the mouth FOGS _ tARVAE of the Chesapeake Bay (Leim and Scott 1966), cunner [96 19 M occupy rocky coastal habitats (Bigelow and Schroeder 1977 58 1 28 1 1953; Serchuk 1972; Olla et al. 1975,1979; Dew 1978 Ito 1976; Pottle and Green 1979), and exhibit highly 1979 5870 21301- 1325 92 40 k)calized abundance in their home ranges (Gleason and 1980 8223 2 1645 58 i19 143 2 83 . Recksiek 1988). In cold weather,(water temperatures below 8'C), they become torpid (Green and Farwell Ij8I8 j7'0l f 3 8 15 i 1983 7068 1 2679 49 126 198 1 246-1971; Green 1975; Dew 1976; Olla et al.1979). 1984 5719 2 1:46. 422 37227 Eggs are pelagic and hatch in 2-6 days depending on 1985 7484 2 2659 12 2to 30 t 11 water temperature (Williams 1967; Dew 1976; 1986 2969 1082 52 825 Fritzsche 1978), Cunner mature in I to 2 years and the maximum reported age is 10 years (Dew 1976). [ $ -['f6 i -4 2 i All life histocy stages of cunner are found in the
- Data seasonatly restricted to May 22 July 23 for ,and MNPS area. Cunner were found as ichthyoplankton, June August forlarvae.
Fish Ecology Studies 101 i i
EGOS AT EN Cunner and tautog egg hatchability indices (Wil-
""* liams et al.1973) were calculated using the ratios of e wnuNr '
j sixxr /g 0
, "2^"Nr i "2^"*
nimacNn annual 6-mean densities of larvac to eggs at EN
/ '. ', /tj (Table 17). 'lhese ratios were low, indicating poor
@, hatchability. Williams et al. (1973) also found low g"Sxur gi, ,,4w j ' Y (ij cunner egg hatchability (about $%) in field-collected h /*,, eggs, although, their estimates did not take into b ,,x; j account losses due to predation. Since 1984,
}jr ' hatchability was even less than usual and probably l produced fewer juvenile recuits. The annual
- g g hatchability indices were nearly the same for cunner 15 s is s'i n 6 and tautog and were significantly correlated ( r2=o,93, p<0.001), - suggesting that factors affecting ,
. LARYAE AT EN hatchability influenced cunner and tautog in a similar an-i
- wnuNniumn.wrr manner.
E Ol't*ATIONj OM1ATlON k 1* l The 6-mean trawl catch was calculated for threc
- 8. I (IN, JC, and NB) of the six trawl stations (Table 18).
l T 100' i l TAllLE 17. Cunner and tautog egg hatchability index as the
*,,a,*
p p , I ratio of annual 6.mean densities (noJ500 m3) of larvae to eggs
,- " - ' . - collected at EN.
ib p , ' *m. * , ,
\, * * '
- 4. . . e = '
- ysar Cunner Tanteg_,
75 77 19 81 83 85 87 89 1979 0.0021 0.0081 1980 0.0078 0.0222 1981 0,0118 0.0362 1 ARVAE AT NR 1982 0.0049 0.0192 c / nUNrr E OltRAllON 1984 0.0006 0.0014
/ [nRATIONlTilRIEUNrr
{o tw /, ,
/ I, i
i 1985 1986 0.0018 0.0006 0.0062 0.0014 6
/ 'g' '
; I I
1987 0.0009 0.0029 gap 12H 0.0015 0n068 1 6 1 0
, .u ! TAllt.E 18. The 5-mean* catch (noJ0.69 km) and 95% confi-d . , , , k..lI dence intervals of cunner collected by trawl at selected stations
{ mo_ ' l. . . e **, for each report year during June 1976 through May 1989. 75 5 I9 8'l b d b N Ynt IN JC NR YEAR 1976 221 19 di 2.0 11 0.7 Fig.18. The annual (~) and running (-) 6.mean density 1977 301 23 31 1.0 Ii 0.6 (no./500 m3) of cunner eggs at EN and larvac at EN and 1978 613.7 '31 1.4 0.710.3 NB. 1979 291 23 91 5.0 2 1 1.0 1980 231 16 61 2.0 311.2 1981 121 10 51 2.2 32 0.9 82 i The relationship between annual larval to egg abun-3 513j 3 2j 2 i 6 dance was evaluated using 6-mean densities (Table 1984 21 1.0 21 1.0 R41 R2 16). Egg abundances were relatively similar among 1985 11 0.6 11 0.5 OA 1 0.7 years (except for 1986), but larval abundances fluc- 1986 0.1 1 0.2 a51 0.4 0.11 0.1 tuated. The considerable changes in larval abundance 1987 a21 n2 a4i n2 021 on appeared unrelated to density dependant factors. The 1988 a31 al 313 A 221 at annual abundance of eggs was consistently much
- Data seasaorally restricted to May August at IN, May.
larger than that of larvac. sepiember at JC, and April-November at Nil. 102 Monitoring Studies,1989 l
Since 1980, a decline in abundance was evident, but To compare cunner trawl catches with the DEP ran-the 1988 6-mean catch increased at all three statior s. dom trawl survey data, total annual cunner catches Since the early 1980's, the annual 6 mean catch of (calendar years,19761989) were examined. Because cunner has been below the running 6-mean (Fig,19). MNPS trawl sampling effort was similar among flowever, the 1988 annual 6.mean catch at JC years annual cunner catches werc used as indices of increased and was similar to the running 6-mean, relative abundance, and were compared among the six monitoring stations and with the DEP data (Table 19), Tbc 1989 catch of cunner at all the monitoring stations was one of the lowest of the 13 year series. Ls As was seen with lautog, an evaluation of DEP 3* t, CPUE and NUEL CPUE from stations NB, BR and j nn> curt j nnauwrr
#^ #^
23- - I , l TT from 1984 through 1988 revealed a linear
! relationship, rb0.74, p<0.05, (NUSCO 1989) which o
t,
; . 1 l
became non significant when the 1989 DEP CPUE b 5 u- \; I \* l and NUEL CPUE were added (rh0.31, p>0.05). The i! . 1989 NURL CPUE was the lowest of the 6 year d lo'
\, series (19841989), while the DEP CPUE was the
(!* j y 3 i highest since 1984 (Table 19). The DEP catches are
$ ...,J^~^^ done throughout LIS and the increase in catch was a S s s 6 6 6 sr ab result of an increase throughout LIS, including an increase in the eastern end (P, flowell, per, comm.).
There has been an overall decline in abundance at all LC stations around Millstone except NR, but the largest t 7 , gig lgggy decline occurred at IN, This decline began in 1981 g ,, j\ i and coincided with the removal of a fish boom m e l\ l front of Unit 1, A second large decline occurred in g g 6 l \,% i 1983 after the removal of the Unit 3 cofferdam and ' was not unexpected. NUSCO (1976) reported that the l ge cofferdam for Unit 3 would create an artificial em-z
, / bayment potentially attractive to fish during the 2' *,,I
@ / period it was in place. Unfortunately, trawl O ' '[ . . . . monitoring was not donc at IN prior to the installa-
% s s 6 6 6 6 si tion of these structures and ilcould not be determined if these structures actually caused an increase in the cunner population around the MNPS intake.
M1
? .'... Ml$!M$sy Cunner length frequency data from trawls, assigned j af
~~
I an age based on Serchuk (1972), were partitioned into g ! two-unit and three-unit operation periods. The per-
$ 6- I cent length-frequency was calculated for each period g l (each peried equals 100%) to determine if a change e
3 j had occurred since the start-up of Unit 3. Size y . . ' ' " ' ' ,, i distributions differed between the two periods and over 2-
,m , 50% of the cunner caught during three unit operation 6 N . a o _ __ , were young of the-year (Fig. 20 ). Most (>D%) of 75 6 6 6 6 6 6 si the young of-the-year cunner were taken by trawls at REPORT YEAR JC in the fall of 1988.
Fig.19. The annual ( --) and running (-) 6 mean catch Although the abundance of all life history stages of (no/o.69 km) of cunner taken by trawl at IN, JC and NB. cunner at stations close to MNPS has declined, some of the decreases were the likely result of several changes in physical habitat near the IN trawl station. Fish Ecology Studies 103
l i Concurrent with the decrease in trawl catch was an Conclusions _ increase in the percentage of juvenile fish, if changes . in trawl catch were related to entrainment losses, then Abundance data of fishes collected in the fish ; I juvenile recruitment would likely decrease and the ecology ' monitoring programs were examined to relative abundance of older age fish would increase. - determMe wnich taxa were most prone to impacts - l from the operation of MNPS, with emphasis on the . j period of thredunit operations. Six taxa (American .; sand lance, anchovies, silversides, grubby, tautog, and ; TAllLE 19c Atendance indices for cunner collected by trawl in b cunner) were selected for detailed analysis based on DEP8 random trawl survey and in the NUSCO trawl monitoring their abundance ir! the shore zone area of Jordan Cove, prostam, an area which may be thermally impacted or to their - .,
- onl= Nuscob- predominance in entrainment collections.
% im N r_ hB_2.JLTaial.-
~
L ng. term trends in abundance were investigated ; 7 79 36 1 . 78 17 214 ; 88 ~ 23 4 13. 359 usmg runmng 5 means. While anchovy and cunner
)
79 61'992 228- 63 15 22 1,381: eggs had downward abundance trends, the trend for ; SO 9 645 191 91 J4 41 981 tautog eggs was upward. - Except for the grubby; t 81 47 34l 262 85 M 26 -825 : which increased during the period, all selected larval
' [
taxa (sand lance, anchovies, tautog and cunner) had b b 07 ! o 62 either stable or downward trends at all stations. 84 344n00 tows (1.72) 49 M 73' 13 30 17 246 ' 85 98/246 town (0.40) 36 39 30 13 13 12 143 Abundance of the grubby in trawls also increased over L 86 97#15 tows (0.31) 42 9 ;32 10 34 4 131 1 ' time..The 6 mean trawl catch of cunner has been , s 87 129020 tows (0.40) 42 8 14 7 20 4 95 decreasing throughout the decade. 88 72D20 tows (R22) li 13 143 lo 9 10 204 82 2685 20 tows (O ft41 11 36 36 12 16 7 1],3 Factors that may affect early life history survival . have been associated with environmental variables,
' Connecticut Depanment of Environmental Protection (DEP) '
random trawl survey for sin areas in Long lsland Sound. such as water temperature. A significant relationship -
~
(Inden: annual sum of catches and number of tows (average existed between the abundance of young of.the year catch per tow)) (P. Ilowell, pers. comm.). ~ silversides found in the shore zone at JC and July bNortheast Utilities (NUSCO). monitoring data fixed trawl I water temperatures; Annual snnd lance larval survey for six stations la the Millstone area (Fig.1)-(Index: - abundance was also linked to water temECrature, and ' annual sum of catches (0.69 km tows)). l cven though annual larval abundance fluettiated subsentially, March water temperatures explained . some of these variations. ;
^
8 E71NrNix"[n7)N selected taxa collected by seine and trawl between two-g _ x 45 . unit and-three; unit operatior,al periods revealed an g increase in the proportion of juvenile Lautog and r cunner, This change in size distribution could no't be g 3o. altributed to three. unit operation becauce, if entrain-p b ,,,,, g Z - ment losses were affecting recruitment, juvenile: , abundance should decrease and the percentage of older g 15' { ,,,,, fish increase,
$ j q g @
t.ENoVI 3070 71 110 111 140 141 170 171 200 >200 Annual abundance indices of anchovy eggs and 1
-AGE O ! 11 Ill IV V anchovy, tautog and cunner larvae were low m. 1988 ~ Fig. 20. The percent length. frequency distribution, by 89. Anchovy egg abundance was at a historical low" age (Scrchuck 1972), of cunner taken by trawl parti. in 1988. Comparisons ~of annual onchovy egg and wned into two.umt (June 1976.May 1986) and three-larval abundance m. dices suggested compensatory unit (June 1986-May 1989) operational periods.
mortality during the early life history stages, which could help mitigate losses due to entrainment.J Al-1(M Monitoring Studies,1989
l a shough the annual densities of cunner and tautog eggs 5. Silversides dominated the shore zone area of ~ , in 1988 were within ranges found during the previous Jordan Cove and adults were abundant in winter trawi years, the densities of both cunner and tautog larvac collections. There were no apparent changes in were low. An apparent low egg to-larval survival rate annual or seasonal abundance or distribution of seined was found for both taxa in all years examined, but- silversides in Jordan Cove related to the three-unit poorest survival occurred after 1983, prior to the thermal plume. - three-unit operational period. Similar Guctuations in . the annual abundance of anchovy, cunner and tautog 6.- GrubH larvac wcre present in ichthyoplankton larvac, suggested that factom affecting larval survival collections and juver.!!cs and adults were present in were similar for these three .:pecies, trawl collections. Although grubby larval entrain- i ment has increased with the operation of Unit 3, no adverse abundance decrease occurred. Stimmary .
- 7. The tautog is an important commercial and recrea. -
- 1. The operation of MNPS could affect fish as- tional fish in the Millstone area,- and the greatest semblages in the Millstone area in several ways. ~ potential impact of MNPS is through egg entrain.
Juveniles and adults could be lost due to impingement ment. Egg abundance, the best index of adult stock on the intake screens. The mortality rates of early size, had an upward abundance trend in recent years, life history stages may be increased by entraining but larvil densities have declined, An apparent poor eggs and larvae through the condenser cooling water egg to-larval survival in all years examinedcwith the system. The local distributions could be altered by . lowest rates occurring after 1983. the thermal plume.
- 8. Abundances of most life history stages of cunner
- 2. One hundred and eighteen fish taxa have been col- collected near MNPS have declined, but juvenile abun-lected since 1976 in the- monitoring programs: dance in 1988 increased, especially at JCc Part of the demersal trawl, shore zone seine, and ichthyoi decreasing trend in adult abundance was probably ax plankton. Six taxa were selected for detailed ex- result of removal of prefered habitut at INJ An amination due to their prevalence in entrainment apparent low egg to larval survival for all' years was collections or their abundance in the shore-zone area examined, and, poorest survival occurred in recent of Jordan Cove, an area which may be impacted by' years, similar to tautog.
the thermal plume. Long term trends in abundance r were examined for various life stages of potentially 9. A higher proportion ofjuvenile tautog and cunner impacted taxon, were collected in trawls during the three-unit opera- 1 tional period than ~during the two unit operational
- 3. The American sand lance was primarily collected period. This change in size distribution pou!!! not be ,
tis lasvac and was a dominant entrained taxon. Annual . attributed to increased entrainment due to higher - i 1 sand lance larval abundance was linked to water - cooling water usage for three-unit operation, because - l temperature, and even though annual larval abundance increasing entrainment losses'should result in fluculuated substantially, March water temperatures decreasing juvenile abundance and increasing propori explained some of the variation. tions of older age fish. ! 4. Several life history stages of anchovies were col- 10, . Similar fluctuations in the annual abundance of - l: lected in sampling programs. Juveniles were caught anchovy, conner and tautog larvac, suggesting that - by trawl, and eggs and larvae were found in entrain- factors affecting larval survival were similar for these ment samples in 1988, larval densities were low and three species. egg densities were at a historical low. Comparisons of annual egg and larval abundance indices suggested j compensatory mortality duririg the early life history stages, which could help mitigate losses due to entrainment. Fish Ecology Studies 105
m . . t j q y d a References Cited 1
. = 1977 The problems'on' stock and recruit . 4 Bailey, K.M.1984, Comparison of laboratory rates ment. Pages 116-133 in J.A. Gulland, ed. Fish 1 {
of predation on five species of marine fish larvac population dynamics. John Wiley and Sons, New s
~ 1 by three planktonic mvertebrates: effects of larval York.J size on vulnerability. Mar. Biol. 79:303 309.;
. and J.G.K. Harris." 1973. Stock and recrun.
i ' M
=
Bannister, R.C.A., D. Harding, and SJ, Lockwood.t . ment and the' problem of density dependence. j 1974. Larval mortality and subsequent year class : Rapp. P. v. Cons, int. Explor, Mer 164:142-155. l strength in the plaice (Pleuronectes platessa).. . ,. 1 Pages 2138 in J,M.S. Blaxter, ed. The early life' : DeAngelis, D.L;. S.W. Christensen; and A.G. Clark.' _ -( history or fish. Springer Verlag, New York. 1977,z Response of a fish population model.to = :; young-of the-year mortality, Oak Ridge National 4 Beck, A.D'.'and H.A. Poston 1980. Effects of dict
' Laboratory Publ. No.1065. y on survival and growth of the Atlantic silverside. . ,.. , .. . ,. . . , ;
Prog. Fish. Cult 42;138142. . Dew, C.B.1976.1A' contribution of the' life history; }
- of the cunner, Tautogolabrus adspersus, hGish:ts . ;
Bigelow, H.B., and W.C. Schroeder.1953. Fishes ' Island Sound Connecticut. Chesapeake Sci;1 ~ d of the Gulf of Mainec :U.S. Fish Wildl. Serv, .14fl01ll3.. ; Bulla 53:1577. Fritzsche, R.Af 1978. : Develop' ment of fishes of the ' j
-Blake, M.M;, and E.M. Smith. 1984. A marine MidJAtlantic Bightf An atlas of egg, larval and ! .i resouces management plan for the State of Connec- ' juvenile stages. Vol V{Chattodontidac through {
~
ticut. Connecticut Dept. Envir. Prot., Mar. Fish. - Ophidiidac; Power; Plant Pro}ect. .Off, Iliott ~ i 244 pp. Serv., U.S. FishLWildl.LServ.;= U.S, Dept. of the ' d
; Interior FWS/OBS-78/12,340 pp?
~!
Bothelho, V.M., and G.T. Donnelly. 1978. "Ai _ . H statistical analysis of the performance of the ' Geomet Techriologies.Linc. > l983.EPreoperationall k Bourne plankton splitter, based on tett obscr- . aquatic ecology study Shoreham Nuclear Power - i vations. NMFS unpub. ms. Station,-Unit 1,'1982. - Prepared for Long Island ' ]
- Lighting Company, Hicksville, NY.
- Briggs, P.T., and J.S. O' Conner. 1971. Comparison .
1 of shore zone fishes over natural vegetated and - Gleason T., and C. Recksick, fl988;; Synopsis of sand filled bottoms in Great South Bay, N.Y. . biological'dataiforLthe' cunner Tautogolabrus [ Fish Game J. 18;15 41. . adsperaus (Walbaum)g Univ. of Rhode Island,: , Contrib 2420 of the Rhode Island Experimental! q ' Clark, J.1967. Fish und man. Littoral Soc. Spec. Statiori. , Pub. No. 5:178. Greeley, J.R,519381 Fishes and habitat conditions of i Cooper, R;A. 1965. Life history of the tautog, the shore zone' based upon July and' August .
'Tautog onitis (Linnaeus). Ph.D. Thesis, Univ, of seming investigations.0 Section 11. Pages 72-91 Rhode Island, Narragansett, RI.153 pp. in A; biological survey of the saltwaters of Long j island, Pt.11. N.Y Conserv. Dept.L j Cushing, D.H. 1973. Recruitment and parent stock :
in fishes. University of Washington, Div. of Mar. Green,' J.M. 1975. . Restricted' movements .andt Resources, Washington Grant Publ. WSG 731. homing'of the cunner, Tautogolabrus adspersus . 1 197pp. ,(Walbaum) (Pisces; Labridae). ;Can. J.- Zooli 7 53:1427143L l 1974. The possible density dependence of . larval mortality and adult mortality-in fishes. , and M. Farwell! 1971i Winter habits of the - d Pages 103-111 in J.H.S. Blaxter, ed. The early cunner, Tautogolabrus adspersus (Walbaum), in i life history of fish. Springer Verlag, New York. Newfoundland. Can. J. Zool. 49:1497 1499J
.g 106 Monitoring Studies,1989 j
.. -a _m , t , , . . . . . _
- . - + , i ..i
I l l Grossicin, M.D., and T.R. Azarovitz. 1982. Fish Johnson, M.S.1975. Biochemical systematics of distribution. MESA New York Bight Atlas the atherinid genus Af enidia. Copeia Monograph 15. New York Sea Grant Institute, 1975:662 691, Albany, NY,182 pp. Kuntz, A.1914. The embryology and larval develop-llennemuth, R.C., J.E. Palmer, and B.E.11rown. ment of Bairdiella chrysura and Anchovia 1980. A statistical description of recruitment in inischilli, U.S. Bur. Fish., Bull. (1913)33:1 19. eighteen selected fish stocks. J. tierthwest Atl. Fish.1:iOl 111. Leak, J.C., and E.D. Iloude. 1987. Cohort growth and survival of bay anchovy, Anchoa tnitchelli, Ilildebrand, S.F.1922. Notes on habits and develop- larvac in Biscayne Bay, Florida. Mar. Ecol. ment of eggs and larvae of the silversides Afenidia 37:109-122. menidia and Atenidia beryllina 11ull of the U.S. Buireau of Fisheries Vol. XXXVIII. Leim, A.ll., and W.B. Scott. 1966. Fishes of the Atlantic coast of Canada. Bull. Fish. Res. Board
.1943. A review of the American anchovies Can.155. 485 pp.
(Fnmily Engraulidae). Bull. Bingham Oceanogr. Coll. 8:1 165. LeMao, P.1986. Feeding relationships between the infauna and the dominant benthic fish of Rance llorn, M.l!., and R.N. Gibson, 1988. Intertidal Estuary (France). J. Mar. Biol. Assoc, UK, fishes. Sci. Am. 256:M-70. 66:391 401. Iloude E.D.1977. Food concentration and stocking Lund, W.A., and B.C. Marcy, Jr. 1975. Early density effects on survival and growth of development of the grubby, Afyoxocephalus lateratory reared larvae of bay anchovy Anchoa acnaeus(Mitchill). Biol. Bull. 149:373-383. mitchelli, and lined sole Achirus lineatus. Mar. Biol. (Berl.) 43:333-341. May, R.C.1974. Larval mortality in marine fishes
'l and the critical period concept. Pages 3-20 in 1978a, Critical food concentrations for J.ll.S. Blaxter, ed. The early life history of fish.
larvae of three species of subtropical marine Springer Verlag,New York, fishes. Bull Mar. Sci. 28:395-411. McIlugh,J. L.1972. Marine fisheries of New York
.1978b Simulated food patches and survival State. Fish. Bull., U.S. 70:585 610.
of larval bay anchovy, Anchoa mitchelli, and sea bream, Archosargus rhomboidalis. Fish, Bull., .1977. Fisheries and fishery resources of New U.S., 76:483-487. , York Bight. NOAA Tech Rep. NMFS Circ. 401. ' 51 pp.. Ilunter, J.R., and C.A. Kimbrell. 1980. Egg can-nibalism in the northern anchovy, Engraulis Meyer, T.L., R. A, Cooper., and R.W. Langton, mordax. Fish. Bull. 78:811-816. 1979. Relative abundance, behavior, and food habits of the American sand lance, Arnmodytes ; Jamieson, l.G., N.R, Seymour, and R.P. Bancroft. americanus, from the Gulf of Maine. Fish. Bull., ; 1982. Use of two habitats related to changes in U.S. 77:243-253. ; prey availability in a populanon of Ospreys in nor- 1 theastern Nova Scotia. Wilson Bull. 94:557-5M. Montelleone, D. M., W.T. Peterson and G.C. Wil-liams. 1987. Interannual fluctuations in the density of sand lance, Ammodytes americanus. Jefferies, ll.P., S. Itale, and A. Keller.1988. [ larvae in Long Island Sound, 1951-1983. ' ilistorical data assessment finfishes of the Estuaries Vol.10, p. 246-254 Narragansett Bay area. Narragansett Bay Project Final report. Grad School of Oceanography. University of Rhode Narraganset RI 362 pp. Fish Ecology Studies 107 E
Northeast Utilitics Service Company (NUSCO), Coast. Mar, Sci. 1:361 378, 1976. Environmental assessment of the condenser cooling intake structures (316b Demonstration), . Pearcy, W.G., and S.W. Richards. 1962; Distribu-Volumes I and 2, submitted by Northest Utilities tion and ecology of fishes of the Mystic River Service Company to the Connecticut Department- estuary, Connecticut. Ecology 43:248 259. of Envirmmental Protection. Pennington, M.1983.. Efficient estimators of abun;
, 1987.' Fish ecobgy. Pages 161206 in dance, for fish plankton surveys. Biometrics Monitoring the marine environment of Long 39:281 286.'
island Sound at Millstone Nuclear Power Smtion. Waterford, Connecticut. Annual report,1986. . 1986. Some statistical techniques for es. ' i timating abundance iridices from trawl surveys. 1988a. Delta distribution. Pages 311320 in Fish. Bull,, U.S. 84:519 525, Monitoring the marine environment of Long
' island Sound at Millstone Nuclear Power Station, Pottle, R.A., and J.M. Orcen. 1979.' Field observa-Waterford, Connecticut. Annual report,1987, tions on the reproductive beha'vior of the cunner, -
Tautogolabrus adspersus (Walbaum), in New.
, 1988b, Flydrothermal Studies. Pages. . foundland. Can. J, Zool. 57:247 256; 323 355 in Monitoring the marino environment of . . _
Long Island Sound at Millstone Nuclear Power Richards, S.W. 1959. . Pelagic fish eggs and larvae , Station, Waterford, Connecticut; Annual report, of Long Island Sound. Bull. Bingham Oceanogr, ' 1987, Coll.17:95124
, 1988c. Fish ecology Pages 255 310 in , 1963. The demersal fish population of Long' Monitoring the marine environment of Long Island Sound. Bull. Bingham Oceanogr. Coll.
Island Sound at Millstone Nuclear Power Station, 18(2):1 101, Waterford, Connecticut. Annual report,1987,
.1982. Aspects of the biology cf Anunodytes '
. 198.9, Fish ecology. Pages 161206 in americanus from the St, Lawrence River to j
' Monitoring the marine environment of Long Chesapeake Bay,1972 75, including a comparison I lsland Sound at Millstone Nuclear Power Station, ' of the Long Island Sound postlarvae with Am.
Waterford, Connecticut. Anaual report,1988, modytes dubius. J.- No5thw. Atl._ Fish. Sci.'
- 3:93 IN, Olla, D.L., A.J. Bcjda, and A.D, Martin, 1974. _
l Daily activity, movements, feeding, and seasonal Ricker .W.E.' 1975. Competition and interpretation j occurrence in the tautog, Tautog onitis. Fish. of biological statistics of fish populations. Bull. 4 Bull., U.S. 72:27 35. Fish. Res. Board Can. 191:1 382. ,
. 1975. Activity, movements, and feedi_ng Roff, D.A.1981. Reproductive uncertainty and the ]
behavior of the cunner, Tautogolabrus adspersus, evolution of iteroparity: why don't flatfish put all and comparisoa of food habits with young tautog, their eggs in one basket? Can. Ji Fish. Aquat. Tautog onitis, of Long Island, New York. Fish. Sci. 38: 968 977. Bull.,U.S. 73:895 900. Saila, S.B., and S.D. Pratt. 1973. Mid Atlantic .
- )
. 1979. Seasonal dispersal and habitat Bight fisheries Pages 6.1 6.125 in Coastal and ' 'j selection of cunner, Tawogolabrus adspersus, and - offshore environmentalinventory, Univ, of Rhode j young tautog, Tautog onitis,, of Long Island, Island Mar. Pub. Ser. I New York. Fish. Bull., U.S. 77:255 262.
Sampson, R.1981. Connecticut marine recreational Ll Oviatt, C.A., and S.W. Nixon.1973. The demersal fisheries survey 1979 1980. Conn. Dept. Envir; J fish of Narragansett Bay: an analysis of com- Prot., Mar. Fish. 49 pp. ! munity structure, distribution and abundance. Est. j i 108 Monitoring Studies,1989
] i
Serchuk, F.M. -1972. The ecology of the cunner, Wheatland, S.B. 1956. Oceanography of Long Tautogolabrus adspersus (Walbaum) (Pisces: Island Sound.1952 1954.11. Pelagic fish eggs and ~ Labridae), in the.Weweantic River Estuary, larvac. Bull.' Bingham Oceanogr. Coll.
- Wareham, Massachusetts. M.S. Thesis, Univ, of 15:234 314.
Massachusetts, Amherst, MA, t il pp. . Williams, G.C.1967, Identification and seasonal-Simpson, D.O.1989 , Population Dynamics of the size changes of. eggs of the labrid fishes, Tautog, Tautoga onitis, in Long Island Sound. Tautogolabrusadspersus and Tautog onitis, of M.S. Thesis, So, Conn. State Univ., New ilaven, . Long Island Sound. Copeia 1967:452 453. Conn. 65 pp.
. D.C, Williams, and RJ. Miller, 1973. Mot-Sissenwine, M.B. 1974. Variability in recruitment tality rates of planktonic eggs of the cunner, and equilbruim catch of the Southern New Tautogolabrus adspersus (Walbaum), in Long England yellowtail flounder. J. Cons. Int. Explor. Island Sound, Pages 181 195 in A. Pacheco, ed.-
Mar. 36: 15 26. . Proceeding of a workshop on egg, larval and juvenile stages of fish in -. Atlantic Coast es-
.1984, Why do fish populations vary? Pages tuaries. National Marine Fisheries Service, Middle -
59-94 in R.M. May, ed. Exploitation of marine - Atlantic Coastal Fisheries Center. Tech Pubic communities. Springer Verlag, New York. No.1. L Smith, E.M., E.C. Mariani, A.P. Petrillo, L.A. Witman, J.D. 1985. Refuges, biological disturbance Gunn, and M.S. Alexander,1989. Principal . and rocky subtidal community structure in New Fisheries of Long Island Sound, 1961 1985. England. Ecol. Monogr. 55:421-445. Connecticut Dept. Envir. Prot. Mar, Fish. 47 pp. . Woodin, S.A. 1982. Browsing: important- in ; Snedecor, G.W., and W.C. Cochran. 1967. Statisti- marine sedimentary environments 7 Spionid cal methods! Iowa State Univ. Press, Ames, IA. polychacte examples. J. Exp. Mar. Biol. Ecol. 593 pp.- 60:35-45. Stevenson, R.A. 1958. The biology of the anchovies Anchca mitchelliand Anchoa hepsetus in Delaware Bay, M.S. Thesis. Univ of ' L Delaware, Newark, DE. 56 pp. Tracy, H.C. 1910. Annotated list of the fishes known to inhabit the waters of Rhode Island. R.I.
- Ann. Rep. Comm. Inland Fish. 40:35176.
- Vouglitois, JJ., K.W. Able, RJ Kurtz, and K.A.
Tighc. 1987, Life history and population dynamics of the bay anchovy in New Jersey. Trans. Am. Fish. Soc. I16:141 153. Warfel, II.E., and D; Merriman. 1944. Studies on
. the marine resources of southem New England,1. 1'
- An analysis of the fish population of the shore
. zone. Bull. Bingham Oceanogr. Coll. 9:153.
- )
'Westin, D.T., KJ. Abernethy, L.E. Meller, and B.A. j Rogers. 1979. Some aspects of biology of the !
American sand lance, Ammodytes americanus. , Trans. Am. Fish. Soc. 108:328-331. O Fish Ecology Studies 109 . N
4 a Appendix Tables ,
-)
i
'l r
i t 110 Monitoring Studies,1989
l
.l
?
APPR*1 DIX l_ Uni of nah.. enllected in the Nh 1%da v .-6. imwemme ~ ! hi.ntific n.m. On=m.+ m Trawl- Seine lehthynnlankton
-l
. Acipenser osyrhyncAur Atlantic sturgeon ; ? ~E Alata .aestivals - 1 blueback herring ' '* *
,AIAra nudiocris - *
-l hickory shed ^ . g
. Alosa pseudokarengus alewife ' * *- * .
Alosa sapidusima . ' American shad *:
/Alosaspp.- . .
river herring -* *-
- i
. Aluterus schoepfi ' , orange filefish *
- Ammodytes smeticanur s American sand Ian * * *- * '
Anchoa he/uetus - striped anchovy- .
- j Anekoa mitchillt' bay anchovy . ,* *
- 8l Anguilla vastrata - American eel- *:
- Apeltes quadracut . ' fourspine stickleback *- * * ;
Bairdiella chrysoura ' ' silver perch . .
- llothidae ' lefityed flounder - _.
Bravoortia tyrannut - = Atlantic menhaden ~*- .;
. Drosme brasme ' cusk .* t Carau crysa, ' blue runner * -*
Carau Airpas - crevalle jack i e
- Centropristis striata . -*
- blacir see bass
*~
A Chaetondon ocellatur' spotfin butterflyfish *' Clupeidae ; ' herrings. *- *
*[
' Clupea Aarengus - ' Atlantic herring * '
Conger oceanicar .. congereel * *
. Cyclopterar lumput lumpfish -*
- 7i Cynascion regalis weakfish * * * '
Cyprinodon variegatur sheepskesd minnow -*. * '; Dactylopterar volitans .- . flying gomard . *
- Darysts centroura roughtail sting ray - ~*
Decapterus macarellus ~ mackerel scad . -
-- Enchelyoput cimbri>u - fourbeard rockling l * - "* '5 Etroput microstomat - smallmouth flounder - *
- i Eucinastomar lefroyl mottled mojarra= . -*
- Fhtalaria fabacaria - bluespotted comelfish ; -*
Fumlular diaphanus banded killifish *
' Fuefulue Aeterecluut mummichog *- * .
. Fuululurlucias spotfin killifish ;
' Fun.lulm majain sinped killifish
- i
- Cadidae codfishes '* =*-
- Gaduemorhua Atlantic cod
- s Gatterosteur ocaleatur threespine stickleback. *y * ?*
Gasteresteur wheadaali ' blackspotted stickleback * * *
.5 Godiidae gobic: *- ~*
i
- Goblatoma giouburgi staboard goby * *
.llemitripterus americanus ses raven *
- llippocamput erectar - lined seahorse * *
- Labridae - wresses
- ketophrys spp.! . boxfish -
- Leiostomus xantAurus ' spon _
- Liparis spp, seasnail *-
- Lophius americanus goosofish .
heaniaperwa - , rainwater killifish *
- Lumpenar lumpretaeformis - inakeblenny -* >
Alacrotwrces americanus ocean pout.
- Alelanogrammat aeglefinar haddock ~ $
AfsnticirrAna saxatilh northem kingfish * * *
- Atenidia beryllina , inland silverside ~* *.-
i Alenidia menidia Atlantic silverside . *- *
- Aferlucciar bilinearls silver hake * *- +
Afierogadur tomcod - Atlantie tomcod * *-
;(
c Fish Ecology Studies .I11-._
, mi .
r m. ,
# .J I
a
- AIM NhfYL: "
ca..a irie .-. rw --- Tmwl Calaa teht hvanhah nn Monacenthat h&pslut planchead filorish *
- Monocenthat spp. filefish -
- 3 Mortme americana - white perch. * * <
p Morone sasalitis .' striped bass * *
.]
striped mullet ' Mugil cephalw _ - Mugil cwems - . white mullet Mulle aurate *
. red goatfish - -] *
. Marselis canis - amooth dogfish.. *' '
Myliebatis freminvillei : bullnose rey .* _ . Myosocephalar menaeat ' grubby * * :*
- Myoaocephalar octodecemspinatar -- longhorn sculpin - * *' i
- Myosocephalus spp. sculpin - -.
Ophidiidae cusk ects .. Ophidion marginatum striped cusk eel * ^*:
- Ophidion wehhi ' created cusk4el *- d Opsanar tau *'
oyster toodfish~ . . ., Osmerar mordes rainbow smelt * *- * '
* -+
Paralichthys dentatus summer flounder . __
.[
Paralickshys oblongas _ fontspot flounder *' *L <; Perritus triacanthat butterfish -- Pholis gunnellut rock gunnell '* *: '.* l ' Pollachiar virens - pollock ~L* *- Pomatomas saltatriz bluefish
. Priaconthavaranatav bigeye
- l Priacanthat cruentata, glasseye snapper * .
- Pristugenys alta . short bigeyn '*
Prionotar catolinas northem searobin * * *- Prionotar evolans striped searobin *: *= -* '+ Psealaoleuronectes americanas winter flounder * * * - Pangitiat pungitiar ninespine stickleback' =* , Raja eglanteria clearnose skato :
- 1 Raja erinacea little skate *:
. Raja ocellata wintet skate *' , +
Salmo trutta brown trout * - Sciaenidae drums -
- Scophthalman aquarav . windowpanc *i i
- Scomber tcombrar Atlantic mackeret ~*-
- l Scyliorhinar retifer - chain dogfish -* I Selar crumenopthalmas bigeye scad * .l l '
Selene setapinnis Atlantic moonfish x
- ji Selene womer lookdown -* '*. 3 Synodus fuetens inshore lizardfish --
- Sphyraena burealis northem sennet -*
Sphoeroides maculatus northern puffer * * * .t Squalus acanthias spiny dogfish *' Stenotomas chrysops scup * *- ]i Strongylura marina Atlantic needlefish .
- t Syngnathat farcas northern pipefish * *
- Tautogolabras adspersus cunner * * -* ,
Taatoga onitir tautog *~ *
- e pcrmit
- Trachinosusfalcatar Trachuras fathami - rough scad *
-l Trackinocephalar myops snakefish *
.)
' Trinactes maculatus hogchoker * ;
radiated shanny
- Ulvaria subbifurcata . . *
- Upanear parvar dwarf goatfish
- Urophycis chars ' red hake *
- Urophych tenuis white hake *
- Utophycis spp. - hake * -*
- 1 k
.I12 Monitoring Studies,1989
- h
.I r
< -, , I
l
- APPlWbfX II. Total nombre of Nhes camhi hv trawl and numbe of umnian cocied in mach mr Gune:Mavi 1976-1989.
Taxon 76 77 77 78 78 79 79 80 R0 El RI.E2 R243R3 84 R4 R$ B5.R6 R6-87 R7.RR BR 89 - Num6e nf iamnice 461 46R _ 46BJ61 46R 467 474 4R0 46R 468 46R 465 46R Pseulopleuronectes americana 7415 6045 t7236 1144213296 1074919201 12560 13260 ; P849. 9321 J 8877.13440 ~ Stenotomar cArysops - 1918' 4040 2556 4094 3844 3403 -4896 5268 4206 2640 5205 3632 3294- , . Scophthalmue agnosu -1480 1296 875 1508- 2016 15181 3517 2475 1 2199 2483 1655 1966 ~ 2399 - Anchoa sppi ~979- 580 --2226 16- 109 578: 38- 109 157 10003_ 8038 292 496
. lfaja spp. ' 661 579 362 402 954 696 2797 2493- 15b3 - 3801 2207 2183 2864. A Menidia spp. : 2152 1647- 1463 1340 '882 501 -$18:-583: 322 519 3438 698. 982
' Gadulae . l12 326 230 211: 3296 1424 476 481 -
562 630-- 168: 593? 88 -
' Affosocephale senatar ~266- 636 297 - 342 632 87C 996 ;672 -477 341 : 727 -4341 989 Tautogolabrw adversur s838 875: 400 1399 940 8401 _.611' 362 -248 'i19 :147 63 205 Prionotar spp. 338 322 138 313- 405- 661 1059 ~422 371E 395 436. 159 = 356.
' foralichthys dentatus . 286 : 141 92 ' 75 122-. 240 250 269 1937 281 653 617 360 reprilar triacantAu , 37 44 407 174- 44 69 - l 82 244 . 19 ' -135 132 111 18314 UropAych app. ~ 99 87 .103 69 163- 313 . 615 -286 -251 :272 286 164 .174
- Garterartearaculcate - ; 30 12 47 77 206 .103 63 - 218 (l102- -116 354 - 405/ - 94 ,
Aterluccius bilinearis 425- '163 : 69 ' 134= $58- 220 382 147- 100 -175 197 118' 73 ' Tautoga onish 229 283 263- 270 146'f228 L239 140- 119 .134 215 87 -1 62 Pholis gunnellat - 85- 106- ' 99 65 - ' 251 273- 302 145 127. l$1f.'I86 2031 407-SyngnatAu farew 43; 54 49 -- ,.88 : 151 2641- 232 202 254= 196 207 275 - 321 llemitrpierne americasm 34 ~ 48 39 .148 278.;410 ~ 557 - : 377 125; 41 45 11z 3 Osmerus morda .Ii1 286 90' 5 123 63. 89 :. 26- 227 . 391- 257 249 .152-
. titropar micmrtomne . 43 7 0 3- - 31 91= 94 56' 85 218- 640 190. 359~
Apeltes gedracw - 10 6 24 27 ' 194 - 765-- 76 - -11 112 .130 107 : 52 31 Centroprntis striata 33 ' 9 3 4' - 63 ; 23 - 38 30 .80 412- 16 2 53 roralichthys oblongar 31 ~7 21- 11 51 32 -138 34 - 81 66 72- 28 '123-Afyowcephalat ocrodecemspinarav 11 :10' 97 40 - - 30 145- 172 51 20 13 12 5 -_ 12 : Alosa pseuiloAarengav . II 272 13 17 4 15 $ L26 4- - 16 "208i - - 4-
- Opsana, fau : 98 21 7 18 31 -35 - 25 23- 24- 32 56' 51. 158; Ammalytes americanar . 5 59 128; 36 117- -- 14 19 11 . 19 .6e 11 29 --- 1 Anguilla rostrata 19 16 8- :5 10 -- 37 29 ~ 24 - l 22 - 34 : 28 - 22- ~ 20 Cyclopterar lumpe .' 19 Ii - 28 58 1I O 14. -1 29' 'l 4 1' 441 6 Liparn sip 9 27 .. 10 10 -18 33- 15 16 11 3 18 - 8? 12 -
Cynarcion regafn 9 21 '4 2 '_ 2 45- 7- 0 l- 5 ' 36 =5- . 14 Alosa sapidnsima - 33 -6 1 5 ' 40 12' .0 29 0 0. 1- 1
- Clupcidae .2 1 0 0 0 0= 'O. O. 0- 110 0- O a Clyca harengat . 1 '9 13 0 0' -1 0 '2, 9 63 ~10 -2 <1 SpAoeroides maculata 0 9: 7-16 10 1 141 16 15 , ~7. 3- -! 9-Afattela cann: 2 5 45 11 1- 5 '4- 6' 0-' 2 2 1 2 j lirevoortia tyrannar - 1 14 11 1 1 1 0 1 0- 34 10 4 1- 1 Alosa oestivain ' Limalaferrugined 3 11 8 12 4 1 1 17 5 2. 4 2 .- 2 i AfonacantAmr hopidat 7
3 5 6 5 8 2 4 3 0 15 0:
.6.-
8
'O 4.
8-0; 9
-0 2-23 2
0- -
'j 1 2 1/ippocampar spp, ~ 0 0 0 O_ D O .O I' 4 7 20 12 6 - Aforone americana 8 17 3 5 8 .2 1 0- 0- 0 :0 10- 5 Gobiidae . ~3 0' O 0 4 0- 0 3 -. 7 2 5 10 -
Atacrowarcas americana * $- 7 9 2 -2 2 2 12 3 i1 0- 6- 22 Selene sotapinnis 0 0 0 0 -0 0: 0- 0 1 =0: 0 0' 30 Fntularia tabacaria 2 3 0- 0 3 0 I '0' 8 1 2 0.' .1 - Leiostomu santhurar 5 -6 0 0 0 0 2. O. ;0 3 1 0- 5
' Dactylopterms volitans :3 0 0 0 0 1 3 1 0 1 3 4~ I romatome saltatrix 1 I O 2 1 2 3 3 0 0 0: 2 1 Selene vomer 1 2 0. 0 0 0 0 ~- 0 0 0 IJ l 11 Alosa spp. 0 0 0 'O 0- -0 0 0 .0 0' 0 4 :11 Aluteran schoepfi . 0 2 2 Li 1 0 0 1 I 2 2 0 3 OpAldion marginatum 0 0 0 0 0 0- 0 0: 'l 12 4' 4 4~
fungilias pwtgitias 0. 0 0. 0 1 2 0 0 5 ~ 1. 5' O :0 Gasterosteidae 0 0 0 13 0 0 0 0 -0 0- 0 -0' -0 Alenticirrhus saxatiln ' 0 l 'O l 0 3 1 0 0 -- O 4 2' .I fundular spp. 0 0 0 0 0 5 2 0 0 2 1 0 'l Fish Ecology Studies 113
, a iI;
. AITENDIX11 canunued. . L{
'1Rgan 76 77 77 7B 78 70 79-80 80-B 1 RI.R2 R2-B1 R3-84 R4.R$ ' R5.86_ 86-87 B7.RR k RM -
F- " of '-= 46R 46R 468= 46R 46E* 467 ~ 474 480= 468; 468 46B 465 462: , I = rriacantAus crwasarus, 0: 0 0 -- 01 0 . Ii 0- 2 31 1. I- 11 11.
- SpAyraena burealis - :D ~0 0: :0 -0 0 0- l_ 1: 2- 0? 1 J6- !
Ulverio su66(acasa 0- 2 O. ul; -1 0. 0 0- 1 1: le =4~ . Lophiw anwricanas . 2- ~0- 0- 0- 1: 0- 'It 'l-~ : D 0 1 --- 41 '0~ I synodarforsewi 0- l' di 0: 0: 3 1; Oi 0 0- '0- 0 ,Os , Mullat euratw , O' Ot 1: O 0. 0 2 -O' _0 : 0 .IL OT 4 ~( TracAwe lashamb 0 0~ .Di 4- 0. 0 0 0 0 0: : 0 ~0' 'di ~: Trinectes maculatar s 3' 11 0 D. 0* 0- 0: ~ 0 '. .0 1- ~2' 1: O' Conger oceanica I -O' O 0- ~l- 0- -0< 'O "2L 0. 1: - 1; IJ
-Gasserartew wheatlandi 0. 0 0. 0 0 1p ~ It 0 ;- ; 1:- :2' Oi !! 1*
Morone pasalitis O' 0- 2' 1: 0 .1; 1: ~0- :0' z IL 0; 0= ~0
- Carans crysar t O' O 0- 0 ,1: 0 'l- 0 --- l - :2w 01 0' 0-'
Priesigenys cita _0' 'O l0 ' OL 0; - l' - 0.. 0; ; 2: : l:- l1" .07 0; ,
- f
. CAaesodon ocellasa,- 'O' -O. 0 .0- I: 0: 0; l' Di 0: 1: 1; Enchelyopa, cimbriar - 0 0: 0- 0- 'O. ~l- .:0= 0- 0 + 0; fili1: :1 <1- ,
riiacantAav arenarar . -0: 0 0- O! -0 :0- -OL 0 2- ' l- 'O' 0:
- lottophrys spp. 0- 0 0- 0_ 0 0' 01 0; 3i 0; 0; J O' .0 l.ucania parm . 0- 0 -: 02 0 0 0. -0 01 0 -E 'O. 0 '3 i 0' ,
Afugi/ cephalar : 01 .0 0 04 0: J0, 't. O' 0- E2~ -0' ' 0 " ' 10
- 4 4tosa mediocr!r '
1 0- 0- 0. .11 0 : O. 04 'O- 0~ 0 '02 iOc Caranz Airpos. 0 0' O O- 0 0' l. O, ~0 , I- /01 -: 0- 0;- q Decapterus macarellas ' O 0 0 0 20: 'Ob -0 'O 2; O. 0 :- 'O: OF Melanogrammat aeglefinas 0: 0- 0K 0: : 0 0-: 'O ' 1- .O< 0$ 0~ T17 0 ; Scomber scembras 0 1: -O. I- O. ,Ot :0 0t , 0: Oc :0: -0: -0: -i Squalas acanthias 0 0 0 -0 .0: 05 1: .0- 1i 0: 0L 0s 0= Acipenser-atyrhyncAus 0 0 0' 1" 0- Oh 0: Ot '0 0 0' ~O' O J Autossome maculasa 1 0' O 0- 0 "O -0< 0. -Ot !0: O! 0 - O L-Dairdiella cArysouta - 0 0 0- 0 0; -- D . 0- l' 0: O' O[ 0[ '0[ , Dotkat ocellasas 0 0 ~ 01- 0- 0 =0 li -0 cOr .Us- 0 'O' -0
- Brosme brosme 0 0- 0- 0 0= 0' 01 0 , 01 Of 0' 'tr -0. :;
Cyprinodon variegasas O' O O 0= 0 Os 0: 0- - '0- OL ' li -0= Dasyasir centroura 0- -O' 0- 0 -- 0+ Oi 0; .0 It - 0 :" -0 20' .0-
'MonacantAus spp. 0 0- Oc 0 0- -0, ,0- -0: LO, .0- '19 'OJ -0; .
+
'Myliobatis freminvillei- 0 0 0 0 0' 0' le \0 Oi O' 0: "0- =0 MyosocepAala, spp. 0 0 0- 0 0 0 0 0: or 0 zo . 0
,Ophidisdae 0- 0- O' O. 'O. -04 Or OT 10 '. -
D04 ' 'it; 1: L0i ~0f j Salmo traria 0 0 0 0- Ib 0- 0- 20' 'Oe ' 0 LO' -O' 0= ScyliorAinai renfer I- 0 0: 0 0- 0 0 0- ,0- 0: 05 0: .0'
- Selar crumenoptAalmus 0 D. 0: 'O: O' 0- 0 0- 'O. 1 'Oc :0 ^ 0: x ,
TracAinocephalus myops 0 0; 0 0- 0 -0 - 0: -IL -- 0 : 101 .0. '0( f TracAinotaefalcatar .0 0. 0 0 0- 0: O' ili 1 01 =0- 0- 0J ; Uponens purvar 0 0- 0- 0 0 .0: 0 i0- .1 < -0 ^0" 'O Total 17941 18147'17497 22469 29010 24773 37699 27860:28169: 33546 35566 21074:29529 '
?
?
e i14 Monitoring Studies,1989
*
- tt 4 4
(. ,- [k <
- APPL:NDDt 111 hadumfrri of fithen nunht hv trawl and number of ==malen m11ceted at each station flunc Mavi 1976-1989.
-Taxon y NR NU Tr liR IN No Aceof==m,Jeet 939 937 - 939 939 939 937 s Pseudopleuronectes americanar 12868 48319' 18762 22149- 17511 23082-15tenotomus chrysops . 3288' 257 -19416- -7843- -4745- 13447-Scophthalmus aguosat - 1338 2151 ~ 2283: 3421 12408' 3786i j
- Anchoa spp. 1424 '428 ^1804; 303 - 17 l3407
#aju spp. ,1038 13 3232' 5997 8525 -2777- !
= hiemidia spp 3998- 4907- - !!32. 765 314 3529 Gaadac 1881 756 z 2735 1019 264 1942 h/yozocephalus aenoeme - -1175 3450 406 442 701 1505 Tautogolabrar odtrersur 1567, 344 ;505 261 475 ' 3893 Prionotar opp. . . 86 4 64 l 401 1044 2760- 620
' Paralichthys dentatav 769 1235. 684 1697 227 711=
Pepritus triacanthat 51 - 3 626- 524- 1232 993l r Urophycir spp, 1343, 61 299 261- 1494 .424: Gasterosseous aculeatus 2014 782 :10 7 6 8
' Aferluccius bilinearis !l42 5 393 339 1346 536 Tautoga onitir - 559 -605 274; 188 259' 627.-
Phohs gunnellus 1343: 296- 264~ 155. 24 . . 318 Syngnathus furcut -726 1132 129 80 ' 97 172'
. llemitripterar americanus 443 82- 402 297 492 400-Osmerar mordax 1398 276 130 '79' 70 116 -
10ropan microstoman i12 16 314. 166 913 296 Apeltes quadracar 162 1378 ' 1. 1 =1 2 Centropristis striata 67 150 38 .38. - 38 443" Paralichthys oblongus 0- 4 68. 7 '$89 27 - blysocephalus octodecemspinosnr ^ -3 0 - 52 . 521 : 16-Atava pseudoharengav - 7- M .19. 12 -252 ,-242 Opsanas tau 8 459 'O O O 12. Ammodytes americanas =19 95 5 29 ' 298' ~9=- Angudio rattrata 37 ' 207 0 20 :3 7-Cyclopternt lumpus 142 6 14- 7 2 ' 52 Liuris
/ spp, 22 1 34 31' -- 75 27 Cynarcion regalis 21 .0 26- 11 62 - ' 31 - ;
~Alara sapidissima 8 11 - 52 10- ' 28 . 22 Clupeidae 0
-{'
.) 0, 1_ 0 'liI -
Clupea harangus 65 . 4- 14 9; 15 4 Sphoeroides maculatus lI 59 :9 3' 15 %l
- h/utelis canis 6 1 40 - 3' 132 _4 .,
Brevoortia tyrannus 1 61 13 1 -0 3 Alara oestivativ 1 20 16s 3* 14 - .13 Limandaferruginea 0 0 0 8- 62 0: Afonacanthus hispidas 16 l 8. 7'~ ' 11 :10 1/ippocampus opp. 23 : 18 1 3 1 4 blorone american - 8 13 4 1 5 18 ' Gobiidae 2 41, 0 0 0- 0-Afacrotoarces americanas 0 0' O 1: , 40 -2 1 Selene setapinnis . 0 7. Fhtalaria tabacaria . 16 16 2 0 0- .6 0 2 ~0 3 '3 Leiostomus xanthurns . 4 0 8' O ^4 6 Dactylopterns volitans 1 8 0 0 0 8 . Pomatomus saltatrix - 3 4 3 0 $ 1 Selene womer 0
}.
1 14 -0 0 1 ; Alosa spp, O I 2. 2 9 1 ,
' Aluterns schoepfi 8 0 1 2 1 3 Ophidion marginatum 3 3 1- -2 5
-l 1 t Pungisins pungitins ' 10 3 :D . 0- 0 1' Gasterosteidae = 2 11 0 0 0 n
'hienticirrhns saxatilis 0 2 3 4 1 3
-)
o
=i(
Fish Ecology Studies ~ _115 l'
;f
+
1
. . . d
' ' ~
b
, f
.. .); ^ ; a APKNDIX III annuunad. Tu nn r - hk - M1 ' 'fT HR N
- Fwulule opp.- 14 10 =0= -O. 0 0? -
Priacan'ha crw=Inte b 2 -' 0 1 3> 0: '5 5 Sphyraena borealis ; $_ 6+ 0. - 0; O- 'O
.0 .1: i
^
, Ulvaria subbyacata : -3Y 0 '6L -1 >
0-
. Lophim americano -
Synode fontens 1-01 3t 1^ 0- ' L2: 2. 5 44 l' 0;
'l L!
Mulleaware - '1- .'0- 0 0" 6J
- c:
1^
-t
'l
' Trachwm lethami-. 4. 0- '3 .O Z 0:: ;Ir
^ Trinsetesmaculaan 5: 2 0 D. 'O 1 -1 Conger oceaniew . 1- 2- 2 0- :2- -0~
- Gasterosseus wheatlandi 6^ l- 0 'O O *
~0-
' Morone sanatilk . 0 -. 6 . 0 0=, 'O-Carans crysw 0 0 -: 2. 0/ L1- 2- ,;
Prholgenys alta '2o 0 0 1l 1 :- .1' .i
'O. '0 Chaetodon ocellatus 2 ~2' 0 0 '1 Encholyopas simbrius I ;0: ;Oi .0" ;3 .0 Priacanthm arenate t <0 l- 0 ;O- . ? 21- t Lactophrys p.: 2 1; 'O. 0' 'O- "0- '
Lucaniaparva ' 0' 'O- O' O; , /3
^0; Mugil cephalc 0; i '2 11} ,
0- ~.0, 0-
- j Alosa mediocrh '1 0. .0' .C' 1= 0i Cavan hippos .
0- 0- '0' .0- ')LO- 2^ Decapterm macarellus l 0 ~l: 0 0' 0: L Melanogrammas aeg!sfinns i 0. -~0 ' 1': 0 .1 0' Scomber scombras ' .0 0- 'I 0- 0: 1' Squale acanthins 0~ :0 0 O; 2i 0L ; Acipenser ozyrhynchus 0 0 '1 "0 -0 0' Autostomus maculatns .l. -0; IO .O; O: 0: Bairdiella chrysoura 0. 0- 0.; 0; ;}l .0_ Dothus ocellatur 0" - Ic 0. , -0 L O ': 0. Drasme brosme 0 0 ^o
; -1 0 0:
Cyprinodes <ariegatus 0 l O :D 0 -Oc thayath eentrouva 1 10 . 0 'O 20., 0. Monocanthus spp. :1 0 0- '0 *
' ' O O E. i0 ,
Myliobash freminvillei 0' 'O 1 'O ' 0: 0 , .!
'0
~
, s Myoxocephalus app. O "1~ ;0J 0. ;
;O( ,' -]
Ophidiidae - 0 0- 0 0'. ?!' ;01 4 Salmo f rutta 0- 1 0- ~0- 0? O1 l Scyliorhina retifer :0. 0.
~
0 l - 0 L: 0 < Solar crumenopthalmas 0 0 0 'I: 0 .OL .. Strongylura marina 0 0- 0~ 0. 1 -- <
~0 A Trachinocephalm myops 1 0 0 -O'. .o c0 Trackinotafalcatu O O 'O ?O L :D" 1 Upenensparvur ~ l 0- 0 ?0: 0 0-i.
Total 37300 68257 ,71274 47324 56008 ~-_ .63717- i 7 d y n F
- 116 Monitoring Studies,1989 -
L. r
-- y
~
- F.
a
- ?
+
t i t
-' APPINDDC TV. Total numhers of fishes emuuht by seine and number of emmnles enflected in each year dune Navi 1976-1980. '
lamon 76-77 77 78 7R.70 70-80 80 81 81 82 R2 83 R3 84 R4.R 5 B5 86 R6-87 87 88 88 89 );
- Numher of immnlet 66- 72 72 72 ~72 72 ' ' 98 - 120 174 156 156- 156 156' i Minidia spp. 40619 18194 1335 1062 7996 3186 . 5413 9807 ' 1538 . 13'15 5441 8542 1 6015 -
rumfulat spp. 1695 1199. 815 -659 952 613 915L 1081 ~ 1463 906 111 '432 .3140
. Apeltes qmdrace 464 603' 258 '266- 49 94 89 '1827 167 106 297- 98 152' . Cyprinodon variegatar 48 673 39 30 10 352 146. 50 29 ~ 28 2 2 21- .
Ammodytes americanur 6 520 16 51- -10 318L - 82 21 0 7 .I <4 Pungitiar pungiliar 5 != 28 '2-~ 5 .2' 10 - 321 8 11 '8 .41 30 - ,. SyngnalAur furcar 9 '3 9 108 6 8 21 12 35 30' '33' 19' . 74 Gasterosteur oculearm 9 154 27 5 .3- J 2 .- 5 --. 53 - 6; 6' 19 ' 15 -38. , Pomatomar satratrix 1 0 1- 6- 0 2 -135- 4 35 12 i 12 .5 ;; Afusil cephalur 0 4 3 23 41- 1 4 -4 1 0. 38 '4 45 ; Pseulopleuronectes americanur 4 6 4 1 6 5; '2 3 17 40 . I8 17 - 16
+
Gahdae 2 '0- 9 2 20 16 11 8' Ii 11 8 0 1- : Alosa pseudoAarengur 0 'O O O O -0' O 1 93 0- 0= 4 0-Casterarteur wheattamii 0 0 0- -0 0- 8 '6 6 :19 1 12 9 22. .8 Afugilcurema 0 0 0 0 0- 0- 0- 1 9- 0 0- ~0 43 . Brevoortia tyrannur 0 0 17 0 4- O. 7 1 -: 0 8 6 6 3 i Clupea Aarengur 0 0 0- 0- 0 0 2 0 0- -0 30 On 6 Anguilla rostrata 10 5 12 3 2 'O l l- 0- 0 3 0- LO i Lucuniaparwa l 2 0 0 0 0 0 2 0 ~l 0 16 - 14 ; Afyosocephalut aenatur 3 2 l 2- 0- 'O .3 l- 3 3 :3 2- 4' ! Trachinoturfakarus 0 0- 1 0 3 0 0 0 0. 0 0- 0. 22 3 Osmerar morda 0 0 0 0 0- 0 0- 0- 0- 2 0 0 : 18 Anchoa spp. 0 0 0 0. 2 0. 7 ,2 1 0 0- 01 0 , Gasterosteur spp. 0 0 0 0 0 0 0 0 0 0 12 0 -O' s
~
SpAcevoides maculatur 0 0 0 1 0 -0 l 0 0 3~ 3- 'O - 1 Alara aestivalis 0 0-2 6 0 0 0' 0 0 0 <0. 0- 10. i Carau Airpos 0 0 1 0 0 1 0 0 0 1 0- -O 4 Tautoga onitir 0 0 0 0 0 ~0 -4 0 0 0- 0 -2 .. Tautogolabrus adrpersar 0 0 2 0 0 o' .3 0 1 'O 0-I o 1 Alosa sapidirsima 1 0 0 0- 0 0 0- 0. O l' 0- 0' 0 Afsaticirrhar saxatilir 1 0 1 0 0 0 .0, 0 0 0 0- 0 -0~ Peprilar triacantAur 0 0 0 0 0 0 0- 1- l 0. 0 'O. O. PActis gunnellar 0 0 0 0 0 0 0 0. l'
,Strongylura marina 0- I 0' -0 i 0 0 0 0 0 1 0. 0 0 .0J 0; ;O:
1 i Clupcidae 1 0 0 0 .0 0 0 -0 0 -0 0 0- 0, Cynoscion regalis 0 0 0 0 0 0 '0 0^ l 0 0 0 0 ' : ( Prionotar spp. 0 0 0 0 0 .0 0 0 0 1 0! 0 0 ScopAthalmar aquosur 0 0 0 0 0 0 0-- 0. -0 1 0 .0 0
- Urophycis opp. 0 0 0 0 0- 0 0' 0- 1 0- 0 0 'O Total 42881 21372 2579 2221 9109 4609. 6869 13215 3444 2582 - 6061- 9196 9667 ;
il
)
-1 e
l
- i Fish Ecology Studies 117 2 d
'5
, c <
i
.j i
l e I i
~
APPENDfY V. Total aa-Le* of fi<h== e=nakt tw =aiaa and nnmhar of ==malen entlarad at e.mch statinn (June-Mavi 1976-1939 .
' Tn rm
. JC %P ;fj{ ..
M-Le of da. 462 509 JM ; _' Menidia appe 83546 :15153 .. l's 624 .- i
- Fundule app.. - 10463' 2001: >1517- ,
'. Apeltes quehace '
4435' 17 18 - -i Cyprinadon verlogata 638 ' . 768 24 - Ammad,;es americanus 3- 198 865
; Pungitic pungitim 344 85 6
' Syngnathm fuem . 68 ' $$ 244 ,
! Gasterortensaculeasur_ '275-25 42 ;
. romatomns salvatria 143- 15 -232 ;
Mugil eephalus ' 98 42 ' 29~ ? 25 " I1'. Pseudopleuronectes americanns : Mae . 64- 29 . 103 6=
.]
- Alosa pse'udokarengns 5: 93_ 0 Gasterostems wheatlandi 32 25= 33 '}
Mugilcurema -52 :1. .0 5
; Bravoortia tyrannus . 7' 10 '. ; 35 t 0 !
Clyce hareagus 381 0 Anguilla rastrata 31 2 -4 :; Luconia parm 29- '. 2 .$
. Myozocephalns cenaeus '1 ' l1 .9 l Trackinotusfalcains 24 1 0 ,
Osmerr.s mordas . 1E- 0 '2' Anchoa spp. 11 1 0. ,
' Casterostens spp. 0 .I 11 Sphoeroides maculatus . '0' l 8 -- F Alosa aestivalis 1 .5 -2 Carau hippos. 5 --0' 2 3 Tautoga onitis. ~4 2' 0 ;
Tautogolabro adspersas 5= l 0
, Alasa sapidissima-' 0 -0 2
^ Menticirrhns saxatills 1 -0 1 L
Pepriins triacanthu O :1 1 Pholis gunnellus - -0 -O' 2 ' Strongylura marina 2 0 0
'Clupcidao 0 1- ~0 J; -
Cynascion regalis 1 0- 0 frionotas spp. O I O s Scophthalmas aquosas 0 0 1- 3 Urophycis spp. 0 1 0: :\ Total 100375 18560- '14870 4 y 5 k i L!
.i q
- -j fi 1I8. Monitoring Studies,1989 1 o
i a
-i
Contents - Lobster Population Dynamics . . . . . . . . . . . . . . . . . . . . . - . . . . . . . . . . . . . . . . 121 Introd uction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 Materials and Methods ...................................121 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 123 Abundance and Catch.per-Unit Effort . . . . . . . . . . . . . . . . . . . . 1 23 Population Characteristics . . . . . . . . , . . . . . . . . . . . . . . . . . . . . 126 Size Frequency ...............................126 Sex Ra tios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Reproduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 Molting and Growth . - . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 Culls ......................................133 Tagging Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 Movement ....................-.................... 135 En t rain m e n t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 Conclusions ........................................... 138-S u m m a ry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 8 References Cited .......................................139
/
1
l 1 Lobster Population Dynamics Introduction entrainment and impingement may increase natural mortality of the local lobster population The American lobster, Homams americanus, is and thereby alter recruitment patterns; the heated the most economically important species in Long effluent may affect the behavior of lobsters in the Island Sound (LIS) (Blake and Smith 1984). discharge area. Since 1978, annual landings in LIS have ranged from 1.2 to 2.8 million pounds and yielded The objectives of the lobster program are to between 2.4 and 8.4 million dollars to lobstermen evaluate year to year, seasonal, end between employed in the fishery (Smith et al.1989), station changes in catch per unit effort and in Between 25 30% of the total Connecticut landings population characteristics such as size frequency, during 1989 were made in New London county, growth rate, sex ratios, female size at sexual which includes the Millstone Point area maturity, characteristics of egg bearsng females, (Connecticut Department of Environmental and lobster movements. Since 1984, studies have Protection CT DEP, Marine Fishery Statistics). been conducted during the hatching season to The intense exploitation of lobsters throughout estimate the number of lobster larvae entrained their range has raised concerns over possible through the cooling water systems. Impacts impacts of increased fishing mortality rates on egg associated with plant operations on the local production and recruitment to coastal populations lobster population were assessed by comparing (Anthony and Caddy 1980). In response to results of the 1989 study to other 3 unit concerns raised by fishery managers, biologists operational study years (1986-1988) and to data ; and lobstermen, the Northeast Marine Fisheries collected during 2 unit operations (1978-1985). j Board recommended increasing the minimum Results from the 2-unit period were also legal size of lobsters from 81.0 to 88.9 mm compared to combined 3 unit operational data j 3 (carapace length). In Connecticut, a new (1986 1989) to assess impacts associated with ! regulation was implemented to increase the operating a third unit at Millstone. These results ] minimum legal size from 81.0 mm (3 3/w in) in were compared, when 'appropria4c, to other j 1988 to 84,1 mm (3 % in) in 1992; the minimum studies conducted in LlS and throughout the ' legal size will be increased 0.79 mm (% in) each range of the American lobster, year from 1989 to 1992. This increase should boost larval production and subsequent Materials and Methods recruitment, and in the long term, increase yields. i Lobsters in the Millstone Point area are heavily A detailed description of methods used to ' exploited, with over 90% caught in the first year conduct lobster population studies can be faund after molting to the legal size range. Population in NUSCO (1987a,1988a). Four pot trawls, each dynamics of local lobsters have been studied consisting of five double-entry wire pots (76 x 51 ; extensively since 1978 to determine if operation x 30 cm; 2.5 cm 2mesh) equally spaced along a j of the Millstone Nuclear Power Station (MNPS) 50-75 m line buoyed at both ends, were used to has caused changes in the local population collect lobsters from May through October. Pot- : beyond those expected from natural variability trawls were set near rocky outcrops at three i and the high level of fishing pressure, stations (Fig.1). The pots set in Jordan Cove j The potential impacts of power plant (average depth, 6 m) were '500 m east of the-Millstone discharge. The intake station (average j l operations on the local population of lobsters depth,5 m) was 600 m west of the discharge near 1 include entrainment oflarval lobsters through the the power plant intake structures, ar.d the l cooling water systems, impingement of juveniles Twottee station (average depth,12 m) was and adults on the intake traveling screens, and located south of Millstone Point, about 1600 m
- cffects of the heated discharge. The impacts ,of offshore near Twottec Island. Beginning in 1984, i
Lobster Population Dynamics 121
I k Niont'C y
"a '
%r l North 2 0: U mi
, 7 '
Niontic Boy 5 g JC White Point - ( f DIoa Q Point Bor16ell Reef tig 1. Lxcation of the Muhtonc incicar lwcr Station (MNi'S), and the three loluter 6amphag stations (e), JC=Jott,n Cove, IN = lntale, 'ITa% tree. pots were individually numbered to determinc th Recaptuted cgged lobsters, severely injured or variability in cuch among pots, and to proviac newly moltW (soft) lobsters, and those smaller more accurate values for catch per pot than an than 55 mm CL werc_ released untagged after average catch per pot based on a total of 20 pots recording the almvc data, per sampilng location, pots were hauled on Monday, Wednesday, and Friday of each week, Beginning in 1981, the site at which females weather permluing; on holiday .wecks the pots become sexually mature was estimated by were checked on the first and last work days of measuring (nearest millimeter) the ' maximum the wnk. All lobsters were removed from the outside width of the second abdominal segment of pots; individuals larger than $5 mm carapace all females. Female size at sexual maturity was-length were banded to restrain chelipc<ls, brought estimated by calculating the ratio of abdominal l to the lab, and kept in a tank supplied with a width to carapace length and plotting that ratio - continuous Dow of scaner. The pots were then against carapace length (Skud and Perkins 1%9; rebatted with Dounder canusses and reset in the Krouse 1973). same area. On Fridays, lobsters caught that week . were examined and the following data were Catch per unit effort (CPUE), calculated as the recorded: wx, prer,ence of eggs (berried), carapace number of lobsters caught per pothaut, was length (C1.j, crusher claw position, missing claws, averaged by computing the arithmetic mean; and mont stage (Alken 1973). Imbsters were however, since CPUE data are ration which arc 1 tagged with a serially numbered international not additive and have an asymmetric distribution orange sphyrion tag (Scarratt and Elson 1965;. about the arithmetic mean, the geometric mean Scarratt 1970), and released at the site of capture, was computed to analyze trends in CPUE. The . 122 Monitoring Studies,1989 4
1 l l geometric mean is better suited for constructing lobsters at Units 1 and 3 were mitigated by j asyrnmetric confidence intervals for skewed data installing fish return systems in the intakes, which _l (Snedecor and Cochran 1967). Since 1984, the return impinged organisms to LlS (NUSCO 1986; i number of other organisms caught in cach pot 1987b). Subsequently, NUSCO and the CT DEP ; was counted to examine the influence of agreed to discontinue impingement monitoring i competing species on lobster catch. Because the (NUSCO 1987c). i Cmount of time between pothauls (soaktime or ) set-over days) influences lobster catch, CPUE data Results and Discussion from the commercial lobster fishcry are often ! weighted by soaktime. Catch per unit effort was Abundance and Catch per Unit Effort i adjusted through covariance analysis for the effect of soaktime and the catch of competing species The total number of 7,950 lobsters caught i that significantly (pso.05) affected CPUE.
- during 1989 was within the range of annual total catches for both 2 unit (1,824 9,109) and 3 unit lobster larvac have been sampled from 1984 to (7,2118,871) operational study periods (Table 1). l 1989 during the period of their occurrence (May The lower total number caught from 1978 to 1981
~
through July) at the discharges of Units I and 2. corresponds to data collected with only 10 wire i The Unit 3 discharge was not sampled because of pots at cach station, %c total catch per unit-design problems with the net deployment systcm effort, . CPUE, (total number of lobster used there. Samples were collected with a 1.0 x caught / total number of pots hauled) for 1989 of 6.0 m c<mical plankton net of 1.0 mm mesh. The 1.84 lobsters / pot was also within the range of 2 volume of cooling water r,ampled was estimated unit and 3 unit studies, 1.02 2,10 and 1.70-2.03, from the average readings of four General respectively. The total CPUE for combined 2 Oceanic flowmeters located in the mouth of the net; about 4000 m' of cooling water were filtered unit studies (19/8 85) was lower (1.61) than the in each sample by deploying the net for 45 60 combined 3-unit (1986-89) value of 1.83. Lobster catches by the LlS commercial fishery followed a minutes. Day and night samples were collected similar trend; fewer pounds of lobster were caught four days a week in all study years. Each sampic per pot during 1978 85 (0.860 lbs/ pot) than 1986-was placed in a 1.0 mm mesh sieve and kept in tanks supplied with a continuous flow of seawater. 89 (0.940) (Tabic 1). Shortly after collection, samples were sorted in a Annual geometric mean CPUE for all sizes of white enamel pan; larvac were examined for lobster (legal and sublegal) from 1978 to 1989 is movement and classified as live or dead. Lobster presented in Figure 2. The mean CPUE value larvac were also classified by stage according to the criteria established by Herrick (1911)' fm 1989 @73) was within the range of 3 unit , operational years (1.59-1.93) and 2 unit Entrainment sarsples were standardized as the operational years (0.90-2.01). The time series for
- abundance of larvac sampled per unit volume, The seasonal (May through July) mean density total CPUE has not exhibited any trends I (slope =0.04, p=0.13) since 1978. The minimum was calculated as the mean of the assumed Delta distribution (Pennington 1983; NUSCO 1988b). legal size of 81.0 mm (3 % in) employed from To estimate the total number of larvac entrained, 1978 to 1988 was increased to 81.8 mm (3 % in) the 6 mean density was scaled by the total volume in 1989. The mean CPUE of 0.090 for Icgal-of water pumped through the plants during the sized lobsters (a 81.8 mm) caught during 1989 sampling period. was within the range of prior 3 unit studies (0.089-0.097), when the legal size was 81.0 mm.
Impingement studies were conducted at Unit I # * ## " E" ***'"*"I and 2 intakes from 1975 through 1987; results
" ' # "E " 8 US'
- summarized in NUSCO (1987a; 1988a) included ran m and m im Wen a mm. mean o m sten estimates of total number of lobsters impinged, mean size, sex ratio, and proportion of culls, and a 81.0 mm (the old minimum legal site) in 1989 survival probabilitics for impinged lobsters.
was er an pre sly u p dukg ! Possible impacts associated with impingement of E#'" "b' ' ""#'"E" E "" ' Lobster Population Dynamics 123 l
l l l TANLE 1. Catch statistko for kitalers caught in wirc pots 8 (1978-89) and average catch per pot (Ibs) fed Connecticut kilotermen. j t Total number Number Number pots Tot.11 Pounds / trap { keteter caught tagged hauled . CPUE C1' kitetermen6 ; 1978 1824 1481' '1026 1.78 0.7$0 1979 3239 2398 20$1 1.39 ' O.758 q 19110 28$6 2433 2116 1.3$ - 0.774 - ! 1.02 0.773 t 141 ' 2236 1914 2187 1M2 9109 7$75 4340 2.10 0.969 '(
- 1983 6376 5160 42A$ - 1,49 - 1.069 19a4 7587 $992 4550 1.67 ' O.988 l
' 14$ ' 7014 $609 4467 1.57 ' O.901 '!
1986 7211 $740 4243 1.70 0.810 '! 147 7280 $(A0 4233 1.72 0.922 ! 1998 9871 6H37 '4367 2.03 1.001-IM9 7950 6438 4314 1.84 1.027 :j
- I 2 Unit 1978 8$ 40261 3:582 ' 2$022 1.61 0.860 l 3 Unit 19964t9 31312 2469$ 171$7, 1.83 0.940 -
l 'V
- 10 wire gmts used at each statum trom August through Octotwr 1978, and from May through October 197941; 20 wire pots uwd ' 'f at each statkm from May through October 1981 89. j
- Connecticut lobstermen data prtwided by Connecticut Department of Environmental Protection (Marine lishery Statistics).
4 of lobster c.?ught per trap in the commercial record landings were reported for LIS in 1983 fishcry increat.cd from 1.001 in 1988 to 1.027_in -and 1984. The time series of legal CPUE has j 1989 (Tabic 1). A higher proportion of legal. .shown a - trend .of steady declinc since 1978 - ! stred lobsters (a 81.0 mm) in the 1989 catch was (slope =4).01, p=0.001), most likely due to the I expected becaurie of the large number of sublegal high fishitig pressure for k>briters in LIS. : In our j recruits observed during 1988 (NUSCO 1989). study arca, more than. 90% of' the legal.sizc j Similar tesults werc observed previously; following : lobsters had recently molted from the sublegal; -3 a strong sublegal size class in the 1982 catch, size class.
]
t.a. 6 es . ! 2 00' - 0 4C
' ,M
^
i so .
\ /-
f <;
- m, . :
..n >L g '* j 9 , ,, . ... w 4 s o . 1 1 r ,. cj. 4s}...}. o 4 . . i. L 3
- n. p 'i - .
.i en. M -} . **
.. **f
**n ..........,on .on i >. an a.o ini on ..e in. i.n i a in i .,.
g lig. 2. Mean gcometti: J NE (:t 95% C.I.) for all lotsters (Total CPUE) and legal 4tred lotsters (t 81.0 mm; legal CPUE) from I 1978 to 1989. (O= legal CPUE for lobsters a 81.8 aim). i e 1! ~ 124 Monitoring Studics,1989 t I q L
, , . .. . - - . , 2
i The CPUE was highest in June at all stations Besides lobsters, pots caught other organisms during 1989 (Table 2), which was typical of the which were shown to in0uence lobster CPUE in seasonal pattern of abundance observed in previous years (NUSCO 1989). Incidental catches previous years (NUSCO 1989). Highest catches of all species at cach station were used as were at the Twotrec station (2.91/ pot in June to covariates to identify species which significantly 1.60! pot in October), followed by Jordan Cove (a=0.05) influenced lobster catch (Table 3). (2.37/ pot in June to 1.02/ pot in October) and During 1989, lobster CPUE was influenced by intake (1.95/ pot in June to 1.01/ pot in October). catches of spider crabs, whelks and rock crabs at 1.cgal CPUE (a 81.8 mm) was highest in June at intake, Jordan Cove, and Twotrec, respectively. Twotrec (0.15/ pot) and in July at Jordan Cove Spider crab catches at intake continued to be (0.10/ pot) and intake (0.09/ pot) (Table 2). The high and prev;ously influenced lobster catches in high catches, both total and legal, during the early all but one year since 1984 (Table 3). In summer months (June and July), were related to addition, catches ci whelks had a significant the seasonal increase in water temperature; when innuence on lobste CPUE in three previous water temperature rises above 10"C, lobster study years. More rock crabs were caught during activity (e.g., feeding, movemert, and molting) 1989 (n=540) than in previous years, when their increases (McLeese and Wilder 1958; Dow 1(X6, catch did not influence lobster CPUE. The 1 % 9, 1976; Flowers and Salla 1972; NUSCO incidental catches of rock crabs and spider crabs 1989). TAllt.h 2. Monthly catch statistics for lobsters caught at each station during 1989. Numtwr of Total numtwr Mean CPUE Mean CPUE Legal Total leg,als Month pots hauled caught Arnhmetic Adjusted
- caught CPUE JORDAN COVE MAY 240 546 2.28 2.30 $(17) 0.02 (0.07)
JUN 24 4 615 2.37 2.34 23 (40) (' 0.09 (0.15) JUL 260 544 2.10 2.0R 27 (47) 0.10 (0.18) AUG 259 426 1.63 1.64 17 (23) 0.07 (0.09) SEP 198 294 1.47 1.43 9 (17) 0.05 (0.09) OUT 220 224 1.02 1.07 3 (12) 0.01 (0.06) INTAKE MAY 240 406 1.69 1.81 8 (14) 0.03 (0.06) JUN 257 508 1.95 2.18 21(34) 0.08 (013) JUL 260 501 1.93 2.12 23 (30) 0,09(0.g2) AUG 260 408 1.$ 7 1.42 13 (23) 0.05 (0.09) SEP 200 257 1.29 1.04 7 (13) 0.04 (0.07) OCT 220 222 1.01 0 08 2 (4) 0.01 (0 02) TwoTRT E MAY 240 541 2.25 2.39 20 (36) 0.08 (0.1$) JUN Otio 711 2.91 2.88 38 (59) 0.1$ (0.23) JUL 260 605 2.32 2.29 24 (45) 009(017) AUG 2to 448 1.72 1.72 17 (25) 0.07 (0.10) SI'.P 200 342 1.71 1.64 13 (24) 0.07 (0.12) OCT 220 352 1.60 1.60 16 (22) 0 07 (0.10)
- CPUli values at Jordan Cae adjusted for soaktime and the catch of whetLs, at Intake for the catch or spider crabs and at Twottee tot soaktime and the catch of rock crabs.
6 Mimmum legal sire for 1989 was 81.8 mm. (3 '/ 4 , in); paretithetical values scpresent legal catches under the old legal slic of 81.0 mm. (3 /3 n). i lebster Population Dynamics 125
l
+ 1 TABLE 3. Total number of kitsien and incidental catch of other slec6es caught in tra}m trtsa 1984 1989. l t
1984 19 $ 1966 - 1967 , 1988 -1989 7211 7290 8871 7950 lahoter 7587 7014 f Rocs crab 391. 145. 121 37 54 540' > Jonah crab 74 '. 32 ' 37 71 25 43 , - Spider crab 3237' 1950' 1344' 1754' 7238'- 693R' : llennit crab 428 - 496' -' 435 721' 71t $90 .i mue crab 40 21 26 44 = 71 43 - Winter fkiunder 45 40* 19' 30 , 28 8 l Summer nounder 60 24' 38' 35 28 4 i skata - 15 17 33 14 16 . 54 . Dyster toadIbh 76 67 58 14 33 10' l
$ cup 21 90 2a8 169 97 - - 84 ,
Cunner 141 207 206 167 - 181- 67 i Tsukig 39 250 196 208 44 83 t Sea reven 20 19 6 '2 0 2 wnciks 66 7s* Iw- 132' 27 84' .
~
(*) These caiches significanity auccice not ier cruti(pc005). f i have been reported to significantly affect lobster lobster CPUB at cach station.- Results indicated; catch in other studies (Richards et al.1983; that soaktime had a significant ' influence on. I Richards and Cobb 1987), lobs-ter catch at Jordan Cove and 'Iwotrec during , 1989. The monthly mean CPUE, adjusted for the ' The_ amount of time between pothauts significant covariates -(incidental species - and (soaktime) was also reported to influence lobster soaktime), is presented in Table 2 for cach catch and as a result, commercial fishcry CPUE station, together with - the corresponding data are often weighted for soaktime (Thomas . unadjusted value. The similarity. between the 1973). During 1989 a 3 day soak yleided more adjusted and unadjusted means suggested that, ! lobsters (1.96/ pot) than soaktimes of 2 days although significant, the incidental catch of [ (1.81), 4 days (1.69) and 5 days (0.97) (Fig. 3). competing species and the variability of soaktimes As a result, soaktime was used as a covariate to did not innuence the reliabilliy of CPUE during determine the influence of various soaktimes on 1989. Population Characteristics
** Size Frequency 22
"" 4
-s The mean carapace length (CL) of all lobsters k'* 7F N during 1989 (69.9 mm) was within the range for
"# \ '
3 unit studies (69.5 70.2 mm) but was smaller f, f , than the range reported for 2 unit studies (70.7 i s 71.8 mm) (Table 4). At Jordan Cove, the mean 3'*' \ s CL of 69.8 mm in 1989 was within the range of. j h"" \ both 2. and 3. uni.t studies (69.8 71.1 mm and. ;
\N 69.2 70.2 mm, respectively) (Table 5). The mean - ;
3 3 ; $ CL at _ intake (69.0 mm) was the smallest value , saaet so o4* oars reported since this' study began (range 69.2 71.8 i The- Twotree station has . consistently i mm). yicided the it.tgest lobsters; the mean CL during , 1989 (70.6 mm) was within the range reported i lag. 3. hican catch of lotsters (2 95% c.l.) for a 2. 3. 4, and '! soaktime during 1989, (~) represents 1989 annual mean for 3. unit studies (70.0-71.0 mm) but smaller than - 5 g 7g gg g g 126 Monitoring Studics,1989 y
t l
?
TABLE 4. Summary of kdater carapace length stamtics for wire 74 catches trora May through October,19781989 N* Carapace length (mm) percentage Range Mean195% Cl or legala* r 1978 1508 53-111 71.4
- 0.33 8.7 1979 2846 44 100 _ 71.2.* 0.26 8.2 1980 2531 40 96 70.7
- 0.27 7.2 -
1981 1983 43 96 71.010.33 9.6 , 1982 7835 45 103 70.820.15 7.3 1983 5432 40 121 71.7
- 0.19 10.1 1984 6156 45 107 71.8
- 0.18 9.6 1985 5723 38 101 71.310.17 6.6 - -
1986 5961 36 107 70.110.17 5.1 1987 5924 % 99 70.220.17 4.4 1988 7145 21 97 69.510.16 3.9 1989 6715 34 107 69.920.17 5.5 (3.5)
- 2. Unit 1978 85 34014 3R.121 71.320.07 8,3 (6.3) 3-Unit 1986-89 25745 21 107 69.920.09 4.7 (3.2)
- Recapturca not included.
6 Minimum legal site trom 1978 to 1988 was 81.0 mm (3 #/g in),1989 legal size was 81.8 mm (3 '/,n in). parenthetical values represent p reentage or legals a 81.8 mm. mean CL for data from combined 3. unit years legals in the 1989 catch ($.5%) relative to 1988 : (1986-89) was smaller (69.9 mm) than the mean (3.9%; Table 4). The increase occurred at all ' CL of 71.3 mm for tombined 2-unit years (1978- stations; at Jordan Cove and intake, the 85). Similarly, the mean CL at cach station was percentage of legals increased more than 1% from smaller during 3 unit operation (Jordan Cove 69.7 1988 to 1989 and at Twottee, where 2% more mm, intake 69.4 mm, hotrec 70.4 mm) than legals were caught during 1989.' Although the during 2-unit operation (Jordan Cove 70.6 mm, minimum legal size was increased from 1988 to intake 70.7 mm, hotrec 72.3 mm). 1989, higher landings were reported in LIS for 1989 (2.7 million pounds) compared to 1988 (2.4 The percentage of legal-sized lobsters (a 81.8 million pounds). This increase was expected i mm CL) caught during 1989 (3.5 %) was lower based on out observation of a strong recruit class l than those from prior 3 unit (3.9-5.1%) and 2- during 1988. A similar pattern occurred following unit (6.6-10.1%) studies (Table 4). Percentage of a strong recruit class in 1982, when the - legal stre lobsters at Jordan Cove and Intake percentage of legals caught in 1983 increased by (3.0%) during 1989 was the lowest value reported almost 3E The impacts usually associated with ( since the study began (Jordan Cove 4.19.0%; increasing the minimum legal size, such as lower Intake 3.510.4%; Table 5). The percentage of landings and smaller proportion of-legal sized legal sized lobsters in the catch from Twotree lobsters (Acheson and Reidman 1982) may have (4.2%) was greater than those from Jordan Cove been partly offset during 1989 by recruitment of. and intake. The 1989 percentage of legals at the 1988 sublegal size class. Twotree was within the range of 3. unit values i (4.16.1%) and lower than the 2 unit range (7.1 Sex Ratios 15.3%). The smaller proportion of legal sized lobsters caught during 1989 tcliccted the increase The female / male sex ratio during 1989 was 0.79 ~ l in minimum legal size from 81.0 to 81.8 mm. To female per male, compared to a range of 0.85-comparc 1989 data with previous years results, the 0.88 in prior years of 3 unit operation and 0.79
- proportion of legal sized Ic.bster was recalculated 0.97 during 2 unit operation (Table 6). The i j to include lobsters a 81.0 mm (the old legal sire), female / male sex ratio at Jordan Cove during 1989 -
l ' which revealed an increase in the percentage,of Lobstet Population Dynamics 127
i i k i TAllLE $. Summary of lotster carapace length rtatistka for wire pot catches from May through October,19781989. j v JORDAN N' Carapace length (mm) Percent COVE Range Mean i 95% Cl legals' 1978 499 54 111 703 2 0.$4 4.9 f i 1979 1138 46 96 70.7 2 039 7.6 1980 831 40 93 70.220.45 $.2 - 1981 556 ' 45 93 70.6
- 0 64 7.7 1982 2323 49-96 69.810.26 5.1 !
1983 1965 40 100 71.020.32 9.0 + 1984 1999 52 107 70.720.29 6.7 1985 1722 48 % 71.120.32 6.4 1986 1748 38-99 69.820.31 40 . 1987 1690 44 95 70.2 2 032 4.1
- 1988 '2239 21 97 69.220.29 . 4.1 .;
1989 2077 36 98 69.810.30 5.2(30) , 2-Unit 1978-86 11023 40 111 70.6 :': 0.13 6.7 (4.9)
- 3. Unit 1%6.R9 7754 21 99 69.7 1 01$ 44(28)
INTAKC
- i 1978 645 55 110 71.810.50 10.4 ,
1979 1087 $0-100 '71.410.41 83 1980 855 46-95 70.6
- 0.45 6.2 1981 6R6 43 95 69.220.53 5.0 ;~
1982 2402 $1103 70.210.27. $.8 1983 1436 $2110 71.2 1 037 7.5 1984 1830 43 105 70.5 t 032 6.7 i 1985 1215 44 99 71.220.37 6.0 1986 1888 50-107 69.320.31 4.9 1987 1687 47 94 70.2 1 032 5.2 1988 2253 39 95 69.210.27- 3.3 1989 200$ 39.98 69.0 t 0 32 47(301 2-Unit 1978-86 10156 43 110 70.720.13 6.7 (4.9)
- 3. Unit 1986 89 7833 39 107 69.4 1 013 4.5(30)
< TwoTRun i 1978 374 53-94 72.220.67 10.7 i 1979 621 44 94 71.8 2 0.$8 93 1980 84$ 40 96 713 1 0.49 10.1 1981 741 48 96 73.020.54 .153 1982 3110 43-102 72.0 t 0 2$ 10.2 1983 2031 43 121 72.8 2 032 12.9 1984 2327 $010$ 73.7
- 0.29 14.4 1983 2786 38 101 71.5 10.2$ 7.1 ,
1986 2325 36 97 7t.0 2 0.27 ' 6.1 1987 2547 36-99 70.220.27 4.1 1988 2653 36 93 70.0 2 027 4.1 -j 19N9 2633 70 6
- O 2A - 6.5 f 4 2) 34 @ 7 1
- 2. Unit 1978 86 12835 38 121 72.320.12 "
11.0 (8.5) _ 3.tfnit 1986419 101$8 34 107 704 2 014 52(36)-
- Recaptures not included. '
- Mmimum legal size from 1978 88 was 81.0 mm (33 /u in),1989 legal site was 81.8 mm (3 '/n in). parenthetical values represent percentage of ler.als t 81.8 mm.
was 0.64, which was within the range of previously unit range (0.66-0.97). Twottec catches contained ! reported values: 2 unit (0.(40.79), 3. unit (0.64- fewer females during 1989 (1.08) relative to other 0.71). At intake,1he sex ratio during 1989 (0.65) 3-unit study years (1.151.26) but were within the was similar to 3. unit values (0.63 0.73) and . range of 2 unit sex ratio values (1.021.38). The j contained slightly more males compared to the 2 cxistence of more females at Twotrec- than at. i 128 Monitoring Studies,1989 l
-i .
l 1
. . -- - -~ ---.-.n...- - -- - n. . -.. . - - ~ ., - . _+
1
-l 1
1 i
-l
')
1 TAnLE 6. Female to male ses ratks* or lotsters caught in grogfgefjppg wire pois frorn May through Ociober, 1978 1989.
, Several methods have been used to determine Jonlan iniake hostee . All the site at which females become sexually mature.
C*e - $**** %c presence of external eggs is the most obvious : indication ofg maturity. Templeman (1935) . 1978. o.79 c.97 t.02 ~ c.92 observed that female _ abdominal width markedly.- , 1979 o.6s 0.83 1.1s . o.a2 increases i during ' maturation;7 calculating thei 1 19eo 0.66 . 0.90 Lt5 o.as abdominal width to. carapace length; ratio and; N 19s3 0.72
- o) c.67
-$ 1.25
- 0.87 -
comparing it to CL provides'an index of female-size at sexual maturity (Skud.and Perkins 1%9;" e 19s4 ; ono 0.71 1.22 c.s2
' Krouse 1973). Mean ratios of abdominal width =
-1995 0.70 0.67 - 1.38 : 0.97 to carapace length were calculated for each 5 mm 9s - o$ N .'s CL increment and plotted against the carapace f a 1988 o.68 o.72 t.t$ ' o.as length of lobsters collected for 2 unit-(198185).
1989 0.64 c.65 1.08 - 0.79 and 3 unit (1985 89) operations'and for 1989. alone (Fig. 4). - During 1989, females began to 2.Unli' O.67 0.72 1.2 o.a6 , mature at stres between 50 and'55 mm CL; all-3.Unir - 0.67 0.68 1.t a o.84 females were mature at > 00 mm CL Similar-
- results were reported for 2 unit and previous 3-l necapiunn es inclue41. unit' studies (NUSCO 1989). ' De sire of thc1
* .t ni$
. ' opers' tion ft .' smallest berried females' collected confirmed the -
results of the morphometric relationship between ~ other stations has been consistent since-197$ the abdominal width and carapace length. %c K (Keser et ' al. 1983). Since catches' were smallest herried females collected during 1989.(651 predominantly composed of: sublegal sized mm CL), and in other years of 2 unit and 3. unit 1 lobsters, a s(x ratio close to 1:1 suggested that . operation (62 mm),~ were between 55 60 mr; CL L sublegal sizrJ males and females have similar ~ when oviposition first occurred (assuming 14% frequencies .of molting and similar growth. L in - - growth per molt).L Briggs and Mushacke (1979),' coastal wa. cts of Maine, Krouse (1973) reported ~ using the same-morphometric technique, found a 1:1 sex ratio for a sublegal (< 81.0 mm CL) that females in western LIS begin to mature at population of lobsters. Sex ratlos close to 1:1 60 mm CL and most are mature at about 80 mm: were also reported for lobsters < 80 mm CL by CL Ein contrast 'Oulf of Maine females seldom other rescarchers (lictrick 1911; Templeman become rexually mature at less than 81 mm.CL, - 1936; Ennis 1971,1974; Stewart 1972; nomas and only a small. percentage are mature between 1973; Cooper et al.1975; Briggs and Mushacke 81 and 90; mm CL: (Krouse 1973).1 Earlier 1980). Sex ratios of lobsters caught in maturation of females in LlS than in the Gulf of commercial traps generally contain more females; Maine can be attributed to the warmer LIS water Smith (1977) reported female to male sex ratios temperatures (Smith ~ 1977; Aiken and . Waddy in the LIS commercial fishery ranging between
~
1980). %c sexual maturity of males was'not 1.06 and 1.81. In castern LIS, sex ratios ranged nivestigated in' our study because other between 2.61 and 6.29 for legal sized lobsters rescarchers have documented that the size at caught in commercial traps (Blake 1988). %c which males become mature varies 'only slightly- , predominance of females in commercial catches throughout the range of lobsters. _ in western LIS can be attributed to variation in trapping behavior males begin to. mature (i.e. produced mature 1 related to molting and the reproductive cycle, spermatozoa) at'40 to 44 mm CL, and over half ' ' legal restrictions of landing berried females, and -are mature at-50 to 54= mm CL (Briggs and ; L the fact that mature females molt less frequently ' Mushacke 1979);'in northern: waters (Maine): than males (Ennis 1980). males also begin to mature at relatively small-g stres (50% mature at;44 mm CL; Krouse 1973).L l l' . l.obster PopulAtlon Dynamisc 3 1291 h l. d
- e-e- ,=,,ees w ie,ee .e --s ,w-y, - . , - , -v ep-.,n n--p,3,e&, w. b ,r my.-1
-w-- ee v -f
t i I on. . u s ere,meswee ,, o to . ! ( t.umt) , W j (- - - S umt) ,
!. t . . i ,m. ..ic, O
- h. '
N ' : , o so . !.
* :l e ss. ! !
t O t>o .. .
-o .o so.. = i,o o to no :
CARAPACE LENG7H (mm) , Fig. 4. Morphometric relationship between the abdominal width to carapace lengti ratio and the carapace length for female lotstets. , (~) y=a=ba+c/+dd for 2 unit; (-) 3 unit; (o) 1989 data. ; The percentage of berried females collected values reported for prior 3 unit (Twotree 6,4-9.6%; Jordan Cove 2.4 3.2%) and 2-unit studies during 1989 (6.4%) was greater than the percentage collected in prior 3 unit (3.8 5.7%) (Twotrec 5.3-10.6%; Jordan Cove 0.8 3.6%). The and 2 unit (3.16.2%) study years (Table 7). 1989 value at intake (3.3%) was greater than-Wottee yielded a higher proportion of berried other 3-unit studies (1.9 2.3%), but within the females (8.2%) than intake (3.3%) or Jordan range of 2 unit studies (0.9-4.5%). Berried Cove (2.8%), a trend consistent since 1975 (Keser females werc slightly more abundant when - . et al.1983). The percentages at Twotree and combined data for 3. unit operations (4.9%) werc l Jordan Cove during 1989 were within the range of compared to 2 unit operation data (4.3%) The tat!Lil 7. Percentage of berried females caught at each station and annual carapace length statistics from 1978 89. Percent herried female e All Jordan tniate htete W Carapace Length (mm) Percent = i stations Cove Ranne Mean i 95% C.I. subleral6
-I 1978 3.4 1.4 2.6 53 58 74+88 80.1 21h4 67 1979 3.1 1.9 2.7 7.2 70 64*93 80.521,28 54 .
1980 33 3.5 1.8 5.6 71 66 93 79.121.27 64 198t 4.2 1.6 2.7 7.1 82 69 97 8t.2 2135 52 1982 3.1 0.8 0.9 6.1 108 64 99 80.0 t 1.08 58 1983 4.7 2.1 3.2 8.5 123 66 103 80.521.04 60 - 1984 6.2 3.6 3.5 10.6 173 62 95 79.1
- 0.87 C7 f 1985 6.2 3.5 4.5 8.5 171 63 94 77.U e 0.8) 82 1986 4.8 3.0 23 8.0 134 65 94 78.010.95 75 1987 5.7 3.2 1.9 9.6 158 62 90 76.5
- 0.67 90 19H8 3.8 2.4 1.9 6.4 124 63 - 90 76.9
- 0.82 85 1989 6.4 2.8 3.% 8.2 161 65 98 77 3
- 0.78 81 (85) =
- 2. Unit 78 85 43 2.0 2.2 7.1 836 62 103 79.4
- 039 65 (72) - '
- 3. Unit 86 89 4.9 2.8 2.3 7.6 577 62 98 77.1 1 0.40 83 (87)
I
- Recaptures not included.
- Mmimum legal size from 1978-88 was 81.0 mm (33 /;6 in) 1989 legal de was 81.8 mm (3 /n# in), parenthetical values represent percent sublegal for bertied females < 81.8 mm. .
130 Monitoring Studies,1989 g I.
[ mean carapace length of berried females collected temperature. The Compertz growth function during 1989 was 77.3 mm, within the range of (Draper and Smith 1981) was fitted to annual values reported for 2. and 3 unit studies (77.0- cumulative percent-mott data to estimate the 81.2 mm and ?6.5 78.0 mm respectively). Mean annual dates of peak molting. The inflection carapace length of berried females collected point of the Compertz growth curve (In p/s) was during 3 unit operation years was smaller (77.1 used as an estimate of the time of peak molt. mm) than that observed during 2 unit operation Annual molting peaks werc significantly correlated (79.4 mm), and reflected the larger proportion of with mean . May bottom water temperatures, sublegal. sized berried females collected since suggesting that molting occurred earlier in the 1986. Almost 20% more sublegal size (< 81.0 year when May water temperatures were warmer mm CL) berried females were collected from than average; conversely, peaks occurred later 1986 89 (83 % ) compared to 1978-85 (65 %). when water temperatures were colder than High levels of fishing pressure removes' most average (Fig. 5). During 1989, molting peaked on females shortly after reaching marketable slic or 28 June (average bottom water temperature for after berried females releasc eggs. The stability May was 9.5*C). The earliest molting peak of the LIS lobster population despite current high occurred on 15 June 1986 and the latest on 30 exploitation rates most likely results from females June 1984;- the average bottom water that become mature and bear eggs at stres well temperatures during May in those years were teclow the legal size, 10.2"C and ' 8.9"C, respectively, Cumulative percent molt data were pooled for 2 and 3 unit Multing and Growth studies to comparc _ the timing of peak molts during the two operational periods (Fig. 6). No The 3.1% of lobsters exhiolting near imit significant differences were found in the shape conditions during 1989 was within the range ut (s) and location (#) parameters of the Compcrtz percentages reported in prior 3. unit (2.13.2%) grow 1h curves, indicating that molting peaks were and 2 unit studies (2.5 6.4%). Although molting similar during 2 unit and 3 unit operations. lobsters were observed in the catch throughout Templeman (1936) found molting was delayed 1 the study year (May October), most were caught week for every 1*C reduction in water from late spring (end of May) to early summer temperature. Aiken and Waddy (1980) described (middle of June). The variation in the timing of the influence of varying water temperature on the annual molts was examined to determine a molt cycle and found that at 10"C lobsters quickly relationship with the annual variation in water entered the premolt stage and progressed to ecdysis. l 03Jul < ihr ,
,s.o n 19P9 .000 t_
g t=0,0 D>va. b . [% * ** 2
/
9 f 17J.a . *"" \ g y 1shan ,
~
6S 9'O t5 10 0 15 S MLAN MAY WAf rR TEMOrRATURr ( C) Fig. 3. t.incar relationship tietween the date or peak molting (ins /s. estimated from Gompertz growth runction) and annual tnean tiottom water temperature during May. . Lobster Population Dynamics 131.
~h a
j 1M. y.g 9'O'O -} Do. '*~,, f 4,, ,, p sw w go
.0 (1986-99) poe te
/. ,, ' ,
/
g 70 ,,,,,,,t 7 , 60 p . ~
$0. 2-vad-g O, 40' e
[/ (1990-85)
#*6 677
-y*
e / r=0 221 " 3 g 33 ,./ 1
-t
./
20 / **$one ,
/ #et 639 ~i eoo 207
- 10 o< ' 1 we am ag nuo - see oct
. MONTH Mg. 6. Oompertz grteth functke fitied to rumulative preentage data for molting inleton caught during 2 unit studies (-),3 unit -
studes (--) and during 1989 (o). > L 100 -< l00 MALES , TCMALES i y .
^
b 90 _ O no. -
.o '
so. P 8 bso. .oe E o E .o
*%j
, o-
- o " L o-70 to. [ ;
I "J /. - dy 9" . w - o 'g < V f.*'f' W 1 so. g Do. , , s W. . .. . . . 50 . . . . . _. to 60 70 ao 90 100 60 - 60 . 70 ' so - - to 100 . 1 CARAPACE LENGTH AI TAGGING (MM) CARAPACE LENGTH AT TAGQlf40 (MM) M6LLE rLMALF.S , N Gatwth R2 N- Crowth . R8 2 Unit 379 y=22.168 + 0.005(x) 0.70 2 Unit SR6 y=12.678+0.942(s) 0.79
- 3. Unit 218 y=17.737+ 0.866(r) 0.78 - 3. Unit 383 y=15.06V + 0.904(s) 0.73 : -
y=siac at recapture, satisc st tagging (mm). .;
- Hg. 7. Linear regresskms and parameter totimates for carapace lengths k ugging and tocapture times for male and femaic lobsters .
caught sluring 2. unit (197845; -), and 3. unit studies (199649; -): (0) represent 1999 data.' -l 1132 Monitoring Studies,1989 : * !: i
)
u o
i Simpic linear regressions of pre molt (tag slic) Tant.E s. Claw km ror lotStm caught in wire pots from and post molt (recapture-size) sizes best describe l'78-198'- growth for the size range of lobsters caught in our studies (Wilder 1953; Kurata 1%2; Mauchline Year Percent Percentage Percentage 1976). Regression plots and parameter estimates evil m uins n* ins of growth for males and females caught during 2 ""' '!** '** *l8** and 3 unit studies are presented in Figure 7. Incremental growth for all sizes of lobsters 1978 14.9 14.0 0.9 averaged 9.4 mm (14,3%) during 1989, within the. 1979 15.5 14.4 12 I3 range of values reported during 2 unit studies (8.3 9.5 mm; 12.1 14.4%) but greater than those ly 1982
- t.1 32j 10.4 0.7 0
reported for prior 3 unit studies (8.4 9.0 mm, 1983 . 2.4 11.6 0.s 12.8 13.9 %). Growth of males and females was 1984 In6 9.8 0.7 similar during 1989,and was 9.6 mm (14.3%) and 9.3 mm (14.3%), respectively, incremental growth [ y, 3y
, y 1987 10.3 9.$ 0.7 of males and females during 1989 was greater 1988 11.1 10.2 R9 than reported in previous 3 unit studies (males 1989 12 11.2 1.0 8.2 9.5 mm; females 8.4 8.8 mm), but within the 2 unit range of growth increments (males 7.6 9.9 2. Unit 1978 85 12 0 11.1 0.8 mm; females 8.5 9.7 mm). Growth per molt was 3. uni 19ws9 11.1 102 09 comparable during 2 unit and 3 unit operations, based on the examination of the slopes presented in Figurc 7 and the similarity of growth lobsters, thereb)> reducing injuries and mortailtY.
associated with overcrowded pots (Landers and Increments from 1978 to 1985 (8.7 mm) and from 1986 to 1989 (8.9 mm). Our results are similar Blake 1985). Since 1984, values for claw loss to those of other castern LlS t,tudies, in which (12.3%) have generally been lower than values the average growth of lobsters ranged from 13.4% rep rted before the implementation of escape to 15.8% for males and between 13.8% and vents (148%). Pecci et al. (1978) reported that 15.4% for females (Stewart 1972; Blake 1988), trap related injuries were associated with water
. Briggs and Mushacke (1984) reported 14.5% temperature, fishing pressure (i.e. handling by growth per molt for males and 12.5% for females I hstermen), trap soaktime, and shcIl bardness; of ' in western LIS, these factors, Krouse (1976) reported a posinvc correlation between fishing pressure and the g incidence of culls along the coast of Maine.
Other benefits of incorporating escape vents in lobster traps have been noted by many researchers The percentage of culls, lobsters missing one (Krouse and Thomas 1975;' Fair and Estrella or both claws, was 12.2% of the total catch 1976; Krouse 1978; Pecci et al.1978; Fogarty and during 1989, which was greater than other 3 unit Borden 1980), values (10.311.1%) but within the range of values reported in 2 unit studies (10.615.5%; Table 8). g g Since this study began, the percentage of culls at Twottee has been lower than at the Jordan Cove and intake stations (NUSCO 1987a). _ During The total number of lobsters tagged during 1989,9.7% of the lobsters caught at Twotree had 1989 (6,438) was the third largest since studies-missing claws, compared to 16.7% and 16.8% at began in 1978 (Table 1). The percentage of Intake and Jordan Cove, respectively. Average i bsters recaptured in our pots during 1989 L claw. loss during combined 3 unit studies was (19.2%) was lower than that observed in other 3-lower (11.1%) than during the 2 unit study period unit operation years (21.0 25.2%), but within the ! (12.0%), and may have been related to the range of values reported during 2 unit operations implementation of the escape vent regulation in (14.4 23.9%; Table 9). While the proportion of 1984. The regulation requ;ted that pots contain i bsters recaptured in our pots declined 6% from-- l an opening to allow escape of sublegal stred . 1988 to 1989, the percentage of lobsters imbster Population Dynamics 133
;y t
1 i TABLE 9. tduter recapture statetica for NU$CO (May.0ct.) and commercial (Jan. Dec.) pots from 1978 to 1989. NUsCO Commernal ' Number (%) Percentage Mean Number (%) Percentage Mean tagat' Clem) Lasaf' CL(mm) ; i 1978 498 18.1 16.7 (12.3) 75.5 Im4 32.2 43.6 (35.3) 81,1 1979 722 19.4 11.5 (8.5) 75.1 1778 41.6 27.2 (20.8) 27 4 19hD 322 34.4 18.8 (12 B) 75.7 1.%3 37.5 27.3 (20.8) 76 4 1981 707 16.7 12.0 (10.4) 74.R 1484 35.0 25.9 (22.5) 76.3 e 1982 12H2 16.9 10.4 (R.6) 712 2519 33.2 23.0 (18.2) 75.5 19R3 932 1R.1 11,3 (9.0) 73 6 2246 43.9 27.6 (24.2) 76.9 1984 1431 23.9 IL4 (6.3) 710 1290 21.5 34.3 (29.2) 78.H . 73 1 1185 21.1 78.3 i 1985 1216 22.0 7.7 (5.8) 29.3 (24 6) 19#6 1194 21.0 4.7 (3.3) 72.3 1173 20.4 27.5 (21.6) 78.2 + 1987 1356 23.9 5.5(11) 72.H 1161 20 4 25.3 (21.9) 78.8 19ns 1725 25.2 4.3 (2.8) 72 0 13A4 17.2 26.7 (24.5) 73.0 l 19H9 1233 19.2 9.3 (4.4) 72.9 til? 21.5 218 (20.2) 78.1 , 1978 85 7310 22.5 t 1.0 (8.5) 73.9 12769 39.2 27.5 (22.7) 77.0 i 19 % 89 5508 22.4 5.8 (3.3) 72.5 4N35 19.6 25.9 (22,2) 78.3 ,
"latrnthcucal valuca for pctrentage legal reprencnt lotsters e kl.H inm carapace length. t recaptured in commercial pots increased from record landings were reported in LlS for 1983 17.2% to 21.5% lobstermen recaptured inore and 1984 (NUSCO 1984; Smith et al.1989). ;
tagged lobsters during 1989 than in any other year of 3 unit operation (17.2 2(1.4%); the 1989 value The mean carapace length of lobsters was in the range of 2 unit study resalts (21.1 recaptured in our traps during 1989 was 72.9 mm, . 47.6%). Our traps yicided a similar percentage of which was larger than the values reported for ! recaptures when comparing pooled 2 unit (22.$%) previous 3. unit studies (72.0-72.8 mm). The 1989 [ and 3 unit (22.4%) data; however more lobMers mean CL and combined 3 unit (1986-89) mean were recaptured in commercial traps during the CL' (72.$ mm) were smaller compared to' the period of 2 unit operation (39.2%) compared to ran2e of means reported in 2 unit studies (73.0- , the puoled 3 unit operatiori value of 19.6% 75.7 mm) and to the pooled mean for 1978 85 (73.9 mm). However, the mean CL of lobsters i The percentage of legal sized lobsters (a 81.8 recaptured in commercial pots during 3 unit mm) recaptured in out traps during 1989 (4.4 % ) operations was larger (78.3 mm) compared to 2- ; was greater than any value reported in other years unit data (77.0 mm). He changes in the size of 3 unit operation (2.8 3.3%). A higher structure and percentage of lobsters recaptured in proportion of legal rilzed lobsters were recaptured our traps and commercial traps during 2 unit and in our traps during 2 unit studies ($.812.8%) 3-unit operations are due to the escape vent , compared to 3-unit studies (2.8-4.4%). De regulation implemented in 1984. This trap higher percentage of legal sizel lobsters regulation 66vs escape of sublegal-sized lobsters, recaptured in traps during 1989 was due to and because the majority of out tagged lobsters recruitment of the large sublegal size class are sublegal-sized, fewer were retained in the . observed in 1988. Similar year class strength and commercial traps with the required escape vent. subsequent recruitment to legal slic was observed Conversely, our traps do not contain escape vent: in our previous studies. For instance, the 1982 and retain greater numbers of tagged sublegal-catch was the highest reported for this study and sired lobsters, in castern LIS, Landers and Blake indicated a strong recruit class; in 1983, when (1985) noted a substantial reduction in the . i these individuals molted to legal sizes, the number of sublegal sized lobsters retained in proportion of tagged legal-sized lobsters vented pots without affecting the catch of legal-recaptured in our traps increased in addition, sized lobsters. 3 l 134 Monitoring Studies,1989 y
I i Movertietit. shorter average distance traveled during 1989 may have been related to increarat fishing pressure lobster movement was examined using tag and during this year as a result of the increase in i recapture data from our sampling program and minimum legal size. The extent of lobster ; tag return Information obtained from commercial movement varies considerably; other researchers lobstermen. During 1980, the majority of lobsters have reported average distances traveled by ! recaptured in our pots (95%) were caught at the lobsters at large for 1 year ranging between 3.2 , station where they were released, and, on average, and 16.4 km (Templeman 1935, 1940; Wilder : were recaptured within 35 days. Of the 5% of 1963; Krouse 1981). [ lobsters that moved from the relcar.c sites,4% ! moved between intake and Jordan Cove; these De results of our tag and recapturc studies in. ! animals averaged 49 days between the time of castern LIS Indicate that most lobsters are - ; tagging and first recapture. This pattern of short nonmigratory and remain in the local area. This ; tange movement between the nearshore stations predominance of localized movement is typical for . was typical of movement patterris observed during nean,horc lobster populations and agrecs with 1
- 2. and 3 unit studies (95% and 96% recaptured at results of other tagging studies conducted in the release site, respectively). The percentage of coastal waters of castern North America ',
t tags returned by lobstermen fishing within 5 km (Templeman 1940; Wilder and Murray 1958; of Millstohc Pt. was 99% during 1989, which was Wilder 1%3; Cooper 1970; Stewart 1972; Cooper
- higher than the percentages reported in 3 unit et al.1975; Fogarty et al.1980; Krouse 1980, (94 97 % ) and 2. unit (9198%) studies and 1981; Campbcli 1982; Ennis 1984). Nevertheless, provided additional evidence for the localized since 1978, several hundred lobsters have been pattern of movement (Table 10). The average recaptured by lobstermen in The Race, a deep
, distance traveled by lobsters before they were water channel 10.5 km from MNPS between Lls- !
captured in commercial traps was 1 % km during and Block Island Sound, which indicates a - ; 1989, which was shorter than the average distance migration route for lobsters that exit LIS. Thirty. l observed in prior 3 unit studies (2.64 3.16 km), two lobsters traveled more than 75 km from- t but within the range of values reported during 2 MNPS; some were caught to the south in deep unit operation (1.70 3.01). The higher percentage (300 Im) water canyons (Block,lludson, Atlantis, of lobsters recaptured within 5 km nnd the Veatch) on the edge of the continental shelf, >
' TAnLII 10. 'Ihe average distance (km)loisters moved from Millstone Point for all commercial pots, thone set within 5 km. and those set more than 5 km trem the site.
An teenstures WHhin 6 km or MNPS More than 8 km trem MNPN < Number of Average Number ('1) of Average Numbes (90) of Average tags returned distance (km) tags returned distam(km) tags returned distance (km) 1978 798 3.01 725(91) 1.71 73 (9) 15.92 , 1979 1733 1.70 1665 ( % ) 1.31 68 (4) 11.28 ( 1980 13 0 2.09 1257 (96) 1.25 46 (4) 25.17 sj 1981 1478 1,89 1.49 1451 (98) 27 (2) . 23 49 ; 1982 2509 2.34 2343 (93)- 1.58 13Al 166 (7) , 1983 2258 2.88 2111 (93) 1.70 147 (7) 19.78 .; 1984 12 4 2.33 1230 (95) 1.78 . 58 (5) 13.93 1985 1183 2.84 1977 (91) 1.81 13.40 106 (9) , 1986 1168 2.64 110R (95) 1.76- 60 (5) 18.82 . 1987 1156 2.87 1123 (97) 1.78 40.09 33 (3)
- l. WLR 1371 3.16 1286 (94) 1.81 85 (6)- 23.72 1989 1101 - 1.96 1.80 1086 (99) -15(1) 13.33 1978-85 12550 2.36 11859 (94)- 1.57 15.95-691 (6) 19% 89 4796 2.69 4603 ( % ) 1.79 24.19
. 193 (4)
Imbster Population Dynamics 135
?
f P
-#. ,t. . - -
,. , , - , m ,
i l
-L.
-. y .>
,y .ch l
l
\ 3
~ 4 9 -
f"'# e en A t.-
#5- N %
geh, i,
.s% r '" j
'\ N ,~ I W ,N # 3
\ o --
,e,, a ,s, N ,l
-[ N"
*/ 4 -q't '
(/ o { { % 4-l
- +, ;
()
)
/
,/ ,
b t i
)
[ ! l'ig, s. incation and number ol taga teturned ty summeretal lotstermen for loisters caught mole than 75 km from MiHstone hant f tium 197d to 1989. . others traveled cast where they were caught in ' development of emblyos during late.May and -{ llunards llay, Vineyard Sound, and Nantucket June indicated that hatching was imminent. Only i shoals (Fig. 8). One lobster tagged in 1987 was a few berried females were caught in July, which . ,j recaptured in September 1989 off Chatham MA indicated that hatching 1was nearly < complete. (outer Cape Cod), and represents the During 19H9, larvac werc. first collected on 22 northernmost point of recapture for a lobster May and they were last collected on 28 July. The . -! ingged in our studies. Other rescarchers have total number of larvac collected was 237, which~ ; observed similar exchanges between inshore and was within the range of other 3 unit studies (185 ; offshore lobster populations (Salla and Flowers $71), but' greater than the range of values ; 1968; Urmann et al.1977; Cooper and Urmann reported during 2 unit operation (102143; Tabic 1980; CampbcIl and Stasko 1985, 1986) . 11). Stage I larvac accounted for 90're of the .i; four larval stages collected in 1989, which was .; Entrainment comparable to previous years results, with the ; exception of 1986, when more Stage IV larvac j 1.obster larvac were collected in samples of the wcic collected. The paucity of Stage 11 and.ll!- ', MNPS cooling water from May to July during - larvac during 1989 was similar to previous results. ; 1989 (Table 11). The timing of larvae in the With the? cxception' of a~ singIc day sampic! ! cooling water sampico corresponded to the collected in 1988 that contained 107 Stage 11 and , development of egg masses carried by berried 157 Stage 'lli larvac, very few of thesc larval _ -; females; observations of the shape, color and stages have been collected in our studies (range .; 0-15). Other rescarchers working in southern .l 136 Monitoring Studies,1989 ij 1 4 7
~ . - - . - - -~ ~ - - . - , .- - . + ., ,
Y S.; j
)
TABLE 1. summary of lotster larvae entrainment data : 1969,1973; Rogers et al.1968; Lund atrd $tewart I'"" ** S 1* 1970; Harding et al.1979). ' Slick' lines, often ,; visible on surface waters, delineate mnce where- , singei siase 11 stase ill Stase IV Total wind induced surface currents : converge and .; downwell, in LIS,: ' slick' lines have been ; reported to contain high densities of planktonic-E ""*P ' "#
- organisms including lobster larvae (Cobb et al. '
Day is o o 1 16 1983; Blake 1988). - This mechanism of larval -i
' Nthe 73 '1 1 1t 86 transport may have accounted for the high density 1 Tout as 1 1 12 102 of larvae occasionally otectved in single samples / j g igu,y.py4 The fact that more larvac were collected at night: 1 in 4 of the 6 study years may have been related L ;
Day $6 o 3 2 61 ' to the design of the intake structures and _ larval + l Night 69 t 2 to - 82 Total behavior. The MNPS Intakes have curtain walls' . 1 25 1 s 12 143 which entend about 2 m.below mean low water;- m 14u,.14;4 as a result, the majority of the cooling water is l ~ drawn from 2 m bektw the surface. The early J Ng# ht f4 to [t tit is 6 6tages of lot *1cr larvac exhibit positive phototaxis - Toint 87 11 15 19 232 and disperse from surface waters during darkness . (Templeman 1937, 1939); this behavior and thei s M 18M9 7J W design of the intakes causes young larvac (Stages i Day 104 4 s 3 116 I and W m k mm upWe m enuainmem , Night $6 6 3 4 69 #I RIShl* I Total too 10 8 7 las . 4 N 8 6M *Pl ^"8" The annual 6 mean density (number per 1000- ' m') of lotster larvac collected in entrainment - samples was 0.70 during 1989, which was within -
]
Day 179 107 151 15 45a ', Night $2 3 11 47 113 the range of values reported in other 3 unit- ! Total 231 110 168 62 sti studies (0.63 0.88) but greater than' the- 2 unit, M e 7 MapaaJay range of values (0.42-0,43; Table 12). Densitics.' -( of lobster larvac ranged. from 0.15 to 1.13' peri j
' , Day 24 0 1 s 30 1000 m'in day sampics and from 0.18 to $.93 per1 -
Night ilt9 0 2- 16 207 1000 m' in night samplesc The total number of ; Totat 2t3 o 3 21 237 Im'ac entrained during 1989 was estimated byf .; multiplying the annual 6 mean larval density by 1 New England waters have found similar- high the combined 3 unit cooling water volume from -! variability in both the numbers and stages of May through July. :The 1989 estimate'(393,955) larvac collected (!!ibb et al.1983; Lux et al.1983; was .within the range of other - 3 unit values- . Illake 1984,1988; NAl 1989), (304,695 611.462), but was more than twice the 1 range 1 of: values reported - forf 2 unit ; studies 1 Most larvac in 1989 were collected at night (79.511 138,820)J $1nce the cooling water demand - , (87%), similar to the results of the 1984 (84 % ), of Unit 3- alonc is ' approximately : twice the -i 1985 (57%), and 1986 (80%) studics, in 1987 combined Unit 1 and 2 cooling water demand, ai i and 1988 single day samples contained 52 and 412 doubling of the total number of lobster larvac ! larvac, respectively, which represented 50% and entrained was expectedJ The variability in the- ; 72% of the total number collected for those total number of larvac entrained is related 'to the- Li years. Larval lobster distribution and dispersal- performance of the Millstone Units during the - -i have been associated with- surface circulation hatching season; when all _ Units operate. at full a patterns (Fogarty 1983); higher larval densitics . capacity, . cooling water L demands L are at a ] o have been reported along. windward coasts by maximum and the rcsulting entrainment estimates) , l- many researchers (Tempicman '1937, 1939; are high. The highest estimate occurred in 1988 L j l Templeman and Tibbo 1945; Scarratt 1964,1968, when all Units operated at full cnpacity from Ma'y / '! 1.obster Population Dynamics c137 1 1 0
+ .8 - ,n. , , . . c--~.~ c . ,~. m,- , . , , .- + ,, - .
l l TABLE 12. Annual mean density (number per 1000 m') or lobster larvac in entrainment samples during nic6r mennon of occurrence l and ohnual entrainment stimatn with 95% C.l. ror MNPS from 1984 to 1989. Number Mean Coohng Year larvac dennuy' 95% C.I. Wd.1( Eattmate 95% C.I. [ i 1984 102 0.42 0.19065 189.4 79.511 33.w3123100 19H5 143 0 43 0.22 0.64 322.8 138.820 71.024 20u1$ 6 1986 232 OM 0.431.33 6M.2 $k6.226 2a6.451886/m0 l 19ft? 185 0 63 029 0.91 483.6 304.693 140,256-469.134 ! 1988 571 0.?3 0.29.t.18 R37.6 611,462 242.909 988,390 g
'1989 237 0.70 0.36-1.04 $62.8 393.955 202.h583,450 .
- Mean densitics are calculated as the dcha mean (NUsCO 19NNb and Pennmgton 1983).
- Unit 3 hrgan commercial operation. ;
through July; in other years of 3 unit operation, due to the increase in the minimum legal size. f refueling outages occurred during the larval However, recruitment of the 1988 sublegal stre fcason at one or more of the units, resulting in clan, the second highest total catch reported in . lower cooling water usage and entrainment this study, may have offset substantial declines in estimates. De impacts on the adult population the number of legals caught during 1989.- De ! due to entrainment of lobster larvac are difficult estimated total number of lobster larvac entrained to muess due to the lack of knowledge regarding through the MNPS cooling ; water systems ' survival of larvae and post larvac (Phil"ps and remained high in 1989, when compared to 2. unit Sastry 1980; Cadtly and CampbcIl 1986; Cobb operations, due to the additional cooling weter 1986). A decline in the adult lobster population demand of Unit 3. De effects, if any, of higher
- due to larval entrainment would not become 1stval entrainment will not be apparent at the '
apparent for at least 5 to 6 years until juveniles level of adult population for 4 5 years, when thesc grow to a size vulnerable to capture in out traps. lobsters grow to a size vulnerable to capture in out traps. Conclusions Summary , The American lobster is one of the most intensively exploited species found in LIS. Out 1. Catch per unit effort (CPUE) for all stres of . results indicate that more than 90% of the lobster caught during 1989 was 1.84 loL4ters per lobsters above the ' minimum legal size are trap haul, compared to 1.70-2.03 during prior removed by fishing. %c catch of legal stred 3+ unit operations (1986-88); and 1.02 2.10 during lobsten is highly dependent on the number of 2 unit operations (1978-85). legal CPUE of lobsters in the sublegal size class (lobsters one lobsters t 81.8 mm, the new minimum legal size, molt away from legal size). De citinges observed was 0.090 during 1989 within the range of results in the population characteristics of local lobsters from 1986 to 1988 (0.89-0.97) when the minimum , during 1989 were related to the increase in legal size was 81.0 mm. %c 1989 value was ; minimum legal size and not to power plant lower than the range of results from 1978 to 1985 ; impects. %c fishery objective of increasing the (0.110-0.1%). legal catches have declined since minimum legal size of lobsters during the next 3 1978 and may be related to increased . fishing years is to enhance recruitment and sustain the pressure, , lobster icsourec; larval production should increase , as a larger proportion of berried females are able 2. De mean size of lobsters caught during 1989 to spawn before . reaching legal size, Rc (69.9 mm) was within the range of values proportion of berried females collected in 1989 reported from 1986 to .1988 (69.5 70.2 mm) but was the highest reported in this study and most smaller than values reported during 2-unit studies likely reflected the initial benefits of increasing (70.7 71.8 mm). minimum legal sire Changes in the proportion of legal sized lobsters caught in our traps were
- 138 Monitoring Studies,1989
- 3. Female / male sex ratio during 1989 was 0.79, Changes in the percentage of recaptures in our !
compared to values reported from 1986 to 1988 traps and commercial traps were related to a trap (0.85 0.88). The 1989 sex ratio was within the regulation implemented in 1984 which requires range of values reported from 1978 to 1985 escape vents in commercial traps that allow i (0.79 0.97). %c Twotrec station continued to escape of sublegal sire lobsters; sublegal size I have a higher female / male ratio (1.08) than lobsters comprise over 90% of our total catch. ! Jordan Cove (0.64) and intake (0.65), a trend , observed since the study began. 8. Tag and recapture data collected during 1989 l Indicated thht 95% of the tagged lobsters ;
- 4. The site at which females became sexually recaptured in our pots were caught at the station .L f
mature during 1989 was similar to previous years; of release, and 99% of all the tags returned by females began to mature between 50 and 55 mm commercial lobstermen were from lobsters caught CL and sll females were mature at stres greater within 5 km of Millstone- Point. The average than 95 mm CL. The percentage of berried straight line distance traveled by lobsters caught females collected during 1989 (6.4 %) was the in commercial pots was 1.96 km during 1989, l highest percentage collected in this study (3.1 which was shorter than the distance travelled in 6.2%). The mean CL of berried females during 1986-88 studies (2.64 3.16 km) but within the : 1989 (77.3 mm) was within the range of values range of 1978 85 data (1.70 3.01 km). Some reported from 1936 to 1988 (76.5 78.0 mm) and lobsters (32) traveled > 75 km from MNPS and from 1978 to 1985 (77.0 81.2 mm). The high were caught in waters off Rhode Island, proportion of sublegal slic berried females caught Massachusetts, and in deep water canyons in 1989 (85%), was within the range of previous offshore on the edge of the continental shelf. , observations ($2 909f), and confirms that females $ continue to become sexually mature at a small 9. Stage I lobster larvue accounted for 90% of . sire, the four larval stages of lobsters collected in [ r,amples of the MNPS cooling water during 1989. !
- 5. Imbsters that exhibited near mott c<mditions More larvac were collected at night during 1989, !
represented 3.1% of the 1989 total catch, which similar to results reported in three of the five was within the range of values reported in 2. unit sampling years since 1984. The mean density of ; (2.5 6.49i) and 3 unit studies (2.13.2%). The lobster larvac was 0.70 per 1000 m8 of cooling i average growth per molt during 1989 was 14.3% water, within the range of densitics reported from for all lobsters, slightly higher than in other 3 1986 to 1988 (0.63 0.88) but higher than densitics ; unit studies (12.813.9%), but within the range of
~
reported in 1984 and 1985 (0.42 0.43). The growth values for 2 unit operations (12.114.4%). estimate of total lobster larvac entrained, based on sampic density and total MNPS cooling water {
- 6. Lobsters missing one or both claws (culls) in demand, was 393,955 for 1989 and was within the-1989 comprised 12.2% of the total catch, which range of estimates reported from 1986-88 i was higher than other results reported from 1986 (304,695-611.462) but higher than values reported to 1988 (10.311.1%), but within the range of in 19841985 (79,511138,820). !
values reported from 1978 to 1985 (10.615.5%). References Cited t
- 7. The number of lobsters ' tagged in 1989 (6.837) was within the range of values reported in both 3- Acheson, J.M., and R. Reidman. 1982. .
unit (5/60 6,837) and 2. unit studies (1,481 Biological and economical effects of increasing l 7,575). He percentage of tagged lobsters the minimum legal site of American lobster in recaptured in our pots during 1989 (19.2%) was Maine. Trans. Amer. Fish. Soc. 111:1 12. . lower than that observed for 3+ nit studies (21.0- ; 25.2%) but within the range of 2 unit studies Aiken, D.E.1973. Proccdysis, setal development, (14.4 23.99F). The percent caught in commercial and molt prediction in the American lobster,
- traps during 1989 (21.5 % ) was greater than that (Homarus americanus). J. Fish. Res. Board observed in prior 3 unit studies (17.2 20.4%) and Can. 30:13371344.
within the range of 2 unit studies (21.147.6%). , Lobster Population Dynamics 139 ,
i l 1
, and S.L Waddy. 1980. Reproductive Campbell, A. 1982. Movements of tagged g biology. Pages 215 276 in J.S. Cobb, and B.F. lobsters released off Port Maitland, Nova j Phillips, eds. he biology and management Scotia, 1944-80. Can. Tech. Rep. Fish. Aquat.
of lobsters, Vol.1, Academic Press, Inc., New Sci. No,1136. 41 pp. York. i
, and A.B. Stasko. 1985, Movements of I Anthony, V.C., and J.F. Caddy. 1980. tagged American lobsters, Romarus americanus, l Proceedings of the Canada U.S. workshop on off southwestern Nova Scotia. Can. J. Fhh. !
status of assessment science for N.W. Atlantic Aquat. Sci. 42:229 238. lobster (Homarus americanus) stocks ' (St. Andrews, N.B., Oct 24 26, 1978). Can. Tech. . 1986. Movements of lobsters (Homarus Rep. Fish. Aquat. Sci. 932.186 pp. americanus) taggt4 in the Bay of Fundy, Canada. Mar. Biol. 92:393-404. i Bibb, B.O., R.L Hersey, and R.A. Marcello, Jr. . 1983. Distribution and abundance of lobster Cobb, J.S. 1986. Summary of session 6: ecology . of population structures. Can. J. Fish. Aquat. 1 larvac (Homarus americanus) in Block Island Sound. NOAA Tech. Rep. NMFS Sci 43:2389 2390. - SSRF 775:15-22. [
, T. Gulbransen, B.F. Phillips, D. Wang, and Blake, M.M.~ 1984. Annual progress report M. Syslo. 1983. Behavior and distribution of -!
Connecticut lobster investigations, larval and early juvenile Romarus amencanus, l January Decemtier 1983. NOAA NMFS Project Can. J. Fish. Aquat. Sci. 40:2184-2188. ' No. 3 374.R. 47 pp. ? Cooper, R.A. 1970. . Retention of marks and
. 1988. Final Report Connecticut lobster their effects on growth, behavior and migrations investigations January 1,1983. December 31, of the American lobster, Romarus americanus.
- 1987. NOAA.NMFS Project No. 3 374.R.103 Trans. Amer. Fish. Soc. 99 409-417.
PP- _ , R.A. Clifford, and C.D. Newell. 1975.
, and E.M. Smith. 1984. A marine Seasonal abundance of the American lobster, ;
resources plan for the state of Connecticut. Romarus americanus, in the Boothbay Region j Connecticut Dept. of Environ. Protection, Mar. of Maine, Trans, Amer. Fish. Soc. 104:669 674. Fish. 244 pp. '
, and J.R. Uzmann. 1980, Ecobgy of ,
Briggs, P.T., and F.M. Mushacke, 1979. The juvenile and adult Hamants hmericanus. Pages l American lobster in western long Island 97-142 in J.S. Cobb, and B.F. Phillips, eds. The Sound. NY Fish Game J. 26:59-86. biology and management of lobsters, Vol 11, , Academic Press, Inc., New York.
.1980. The American lobster and_ the pot fishcry in the inshore waters off tbc south Dow, R.L 1966. - The use of biological, shore of Long Island, New York, NY Fish environmental and economic data to predic:
Game J. 27:156178. supply and to manage . a r. elected marine resource. The Amer. Biol. Teacher 28:2630. ;
. 1984. The American lobster in western Long Island Sound: Movement, growth and . - 1%9, Cyclic and geographic trends in mortality. NY Fish Game J. 31:21 37. seawater temperature and abundance of ;
American lobster. Science 164:1060-1063. Caddy, J.F., and A. Campbell. 1986. Summary of session 9: summary of research . 1976. Yield trends of the American , recommendations. Can. J. Fish. Aquat. Sci. lobster resource with increased fishing effort. t 43:2394 2396.- Mar. Technol. Soc. 10:17 25. 140 Monitoring Studies,1989 t
I Draper, N., and H. Smith. 1981. Applied lobster larvac (Nomams amedeanus) in St. regression analysis. John Wiley and Sons, New Ocorges Bay, Nova Scotia in 1975 and 1976 { and.the possible effect that the Canso causeway : York. 709 pp. has had on the Chedabucto Bay lobster fishcry. ; Ennis, O.P.1971. Lobster (Homams americanus) Can. Fish. Mar. Serv. Tech. Rep. 832:102 111. l fishery and biology in Bonavista Bay, Newfoundland,1966 70. Fish. Mar. Serv. Tech. Herrick, F.H. 1911. Natural history of the , Rep. 289. 46 pp. American lobster. Bull. U.S. Bureau Fish. t 29:149-408. t
.1974. Observations on the lobster fishery l In Newfoundland. Fish. Mar. Serv. Tech. Rep. Keser, M., D.F. Landers, Jr., and J.D. Morris. [
479. 21 pp. 1983. Population characteristics of the l American lobster, Romams amcricanus, in t
. 1980. Sirc maturity relationships and castern 1.ong Island Sound, Connecticut. [
related observations in Newfoundland NOAA Tech. Rep. NMFS SSRF 770. 7 pp. t' populations of the lobster (Homarus _ amcricanus). Can. J. Fish. . Aquat. Sci. Krouse, J.S. 1973. Maturity, sex ratio, and size . 37:945 956. mmposition . of the natural population of i American lobster, Romarus amedcanus, along ;
,1984. Small. scale seasonal movements of the Maine coast. Fish. Bull., U.S. 71:165 173. !
the American lobster, Homams amcricanus. [ Trans. Am. Fish. Soc, 113:336 338. . 1976. Incidence of cull lobsters, #omams amcicanus, in commercial and research catches Fair, JJ, and B. Estrella.1976. A study on the off the Maine coast, Fish. Bull., U.S. 74:719-effects of sublegal escape unts on the catch of 724. ; lobster traps in five coastal areas of Massachusetts, Unpublished manuscript Mass. .1978. Effectiveness of escape vent shape ; Div. Mar. Fish. 9pp, in traps . ' for. catching legal stred lobster, , Romarus amcricanus, and harvestabic sized
'[
Flowers, J.M., and S.B. Salla. 1972. An analysis crabs, Cancer borcalis and Cancer irroratus,
, , of temperature effects on the inshore lobster Fish. Bull., U.S. 76:425 432. ;
fishery J. Fish. Res. Board Can. 29:1221 1225.
. 1980. . Summary of lobster, Romams Fogarty, MJ. 1983. Distribution and relative amcricanus, tagging studies in American waters ;
abundance of American lobster, Romams (1898-1978). Can. Tech. Rep. Fish, Aquat. Sci. : amcricanus larvac: New England investigations 932:135 140. during 1974 79. NOAA Tech. Rep. NMFS SSRF 775. 64 pp. . 1981. Movement, growth, and mortality of American lobsters, Homams amcricanus, :
, and D.V.D. Borden.1980. Effects of trap tagged along the coast of Maine. NOAA Tech. :
venting on gear selectivity in the inshore Rep. NMFS SSRF 747.12 pp.
- Rhode Island American lobster, Romarus americanus, fishery. Fish. Bull., U.S. , and J.C. Thomas. 1975. Effects of trap 77
- 925 933. selectivity and rome population parameters on i
the size composition of the American lobster, l , D.V.D. Borden, and H.J. Russell. 1980. Romams americanus, catch along the Maine Movements of tagged American lobster, coast. Fish. Bull., U.S. 73:862-871. i Romams americanus, off Rhode Island. Fish. Bull., U.S. 78:771 780. Kurata, H.1%2. Studies on the age and growth : of Crustacca. Bull. Hokkaido Reg. Fish. Res.. ! Harding, O.C., P.O. Wells, and K.F. Drinkwater. Lab. 24:1 115. 1979. The distribution and abundance 'of > i Lobster Population Dynamics 141
-- - - - . - - - . - ~.-.- .- - . -. -. -
/.
i Landers, D.F., Jr., and M.M. Blake. 1985. %c ._
. 1987b. he effectiveness of the Unit 3 .j effect of escape ' vent . regulation on the fish return pystem 1987. 20 pp.
j American kiteter, #(wiams americanus, catch in eastern Imag Island Sound, Connecticut. . 1987c Justification for discontinuing- ! Trans. 41st Annual Northeast Fish Wild. Cont. impingement monitoristg at M2 tone Unh 2. ~ i l 9 pp. Report sebmitted by Northeast Utilities Service - Company to the Connecticut Department of ! Lund, W.A., ' Jr., and LL Stewart. 1970, Environmental Protection.11 pp. l Abundance and distribution of larval lobaters, 1 Nomams americanus,. off southern - New . 1988a. ~ Imleter population dynamics, j t England. Proc. Nati; Shellfish. Annoc. 60:40- Pages _121145. in : Monitoring ~ the marinc~ a t!
- 49. environinent of lang taland Sound at Millstone -
Nuclear Power Station, Waterford, Connecticut. , Lux, F.E., O.F. Kelly, and C.L Wheeler. 19R3. _ Dree-unit operational studies 1986 1987, , y Distribution and abur.Janoe of larval lotstets 7 . .
. t ,j (Nomams americanus) in Bunards Bay,1 ~.: 198hb.; ; De. usage and antimation of, a Massachusetts, in 1976-79.- NOAA Tech Rep. DELTA means z Pages 311320 in Monitoring. , 1 NMFS SSRF.775:29 33. the marine environment of long Island Sound:
at Millstone Nuclear Power Station, Waterford,, Mauchline, J.1976. %c Hiatt growth diagram ' Connecticut.' Dree unit operational studies for Crustecca. Mar. Biol. 35:79 84. 19tI61987. - l Mcleese, D,W., and D.O. Wilder. 1958. De .- 1989J letster population dynamiai- j activity and catchability of the lobster Pages 1135 ;in- Monitoring . the_ marinc j (H<wmms americanus) in . relation = to environment of long Island Sound at Millstone - t J. Fish. Res. Board Can;
- Nulear Power Station.Waterford, Connecticut. _ 1 temperature. .
15:1345 1354. Annual report 1988. NAl (Normandeau Associates Inc.). 1989. Pecci, K.J., R.A. _ Cooper,L C.D.; Newell,' R.AJ l Seabrook environmental studies,1988. A Cliffold, and . RJ. Smolowitz.M 1978. Ghost 1 characterization of bar,eline conditions in the ilshing J of wated andi unvented kibster,' l Hampton.Scabrook, .arca, 1975 1988.- A Homams americanus, traps. Mar, Fish.' Rev.-- '! preoperational study for Scabrook Station. 40:9-43.' 1 Technical report XX II. . .
}
. Pennington - M.E 1983. -- Efficient estimators of _ j 1
NUSCO (Northeast Utilities Service Company). abundance, ' for : J fish.1 plankton surveys.- 1984. letsier population dynamia. Pages 125 Biometrics 39:281286;: ' ; in Monitoring the marine environment oflang , _ _. 1 Island Sound at Millstone Nuclear Powr Phillips, B.F., andl A.N, Sastry.s _ .1980. : larval: j Siation,Waterford Connecticut. Annualreport : ecology.1 Pages 1157'in J.S. Cobb,' and B.F. ci 1983. Phillips, eds. ne biology and management of' l 1 staters, Vol 11, Academic Prt 3, Inc, .New < j
,1986. %c effectiveness of the Millstone . York.
~
j Unit I sluiceway -in returning impinged organisms to long Island Sound.18 pp. Richards, R.A..- and J.S. Cobb.. (1987.E Une of . s avoidance responses to keep spider crats out !
. 1987a.' lobster population dynamics.' = of traps for Amer can lobsters. TrankAmer L -l Pages 1 42 in - Monitoring the Ematinc ~ Fish: Soc.116:282 285.: l cnvironment of long Island Sound at i .. .
,.; , J Millstone Nuclear Power Station, Waterford, , -J.S. Cobb ? and-. MJ.- Fogarty. 1983. j Connecticut. Summary of studies prior to. Effects - of behavioralE Interactions 4 oni the j' Unit 3 operation 1987. . catchability- of f American lobster," Homams 142 Monitoring Studies,1989 -
j ty
, fl
- i.?
,1
,n,,- ,+y-n , , , erw a , y-+ ,-~vn -.,+ww-e-,,~LT ,rs , ..a+ ,,k nur, +n , s + ww
i i americanus, and two species of Cancer crab. Commer. Fish. Res. Dev. Act, Project No. ! Fish. Bull., U.S. 81$160. 3 253.R.I. 97 pp. , Rogers, B.A., J.S. Qibb, and N. Marshall. 1968, , E.C. Mariani, A.P. Petrillo, LA. Gunn, Sirc temparisons of inshore and offshore and M.S. Alexander.1989. Printlpal fisheries larvac of the lobster, Romanes americanus, off of umg Island Sound, 1961 198$. Omnceticut southern New England. Proc. Natl. Shellfish. Dept. Environ. Prot., Div. of Conservation and i Assoc. $8:78 81. Preservation Bureau of Fisheries, Mar. Fish. ' Program. Salla, S.B., and J.M. Flowers. 1968. Movements i and behavior of berric41 female lobsters Snedecor, O.W., and W.C. Cochran. :1%7. dir,placed from offshore areas to Narragansett Statistical methods. The Iowa State University Bay, Rhode Island. J. Oms, int. Explot. Mer. Press, Ames, IA. 593 pp. - 31:342 351. Stewart, LL 1972. The seasonal movements, ' Scarralt. DJ.1(X,4. Abundance and distribution population dynamics and ecology of the lobster, of lobster larvac (Homan4s americanus) in Romands amen'canus (Milnc. Edwards), off Ram r Northumberland Strait. J. Fish. Res. Board Island, Omnecticut. Ph.D. Thesis, University Can. 21:661680, of Omnceticut, Storrs, CT.112 pp. , t
. 1%8. Distribution of lobster larvac Templeman, W. 1935, Local differences in the (Homan4s americanus) off Pictou, Nova Scotia. body proportions of the lobster, Roman 4s t J. Fish. Res. Board Can. 25:427 430. americanus, J. Biol. Board Can. 1:213 226, c
. 1%9. lobster larvac off Pictou, Nova .1936. Imcal differences in the life history .l Scotia, not affected by bleached kraft mill of the lobster (Homan4s amcricanus) on the l cffluent. J. Fish. Res. Board Can. 26:1931 coast of the maritime provinces of Canada. J.
1934. Biol. Board Can. 2:4188.
. 1970. Laboratory and field tests of _. 1937. Habits and distribution of larval ,
modified sphyrion tags on lobsters (Homarus lobsters (Homants amcricanus), J. Biol Board - ' americanus). J. Fish. Res. Board Can. Can 3:343 347, 27:257 264. 1939. Investigations into the life history I
. 1973. Abundance, survival, and vertical of the lobster (Homands americanus) on the ,
and diurnal distrib'.ition of lobster larvac in west coast of: Newfoundland, 1938,- ; Northumberland Strait 1%2 63, and their Newfoundland Dep. Nat. Resour, Res. Bull. . relationships with commercial stocks J. Fish. (Fish) 7. $2 pp.- , Res. Board Can. 30:1819 1824.
.1940. Lobster tagging on the west coast -
, and P.F. Elson. 1%$, Preliminary trials of Newfoundland 1938. Newfoundland Dep. _i of a tog for salmon and lobsters J. Fish. Res. Nat. Resour. Res. Bull, (Fish) 8.16 pp.
Board Can, 22:421 423. l
, and S.N. Tibbo. 1945. Lobster j Skud, B.E., and 1-l.C. Perkins. 1%9. Size investigations in Newfoundland 1938 to 1941, composition, sex ratio and size at maturity of Newfoundland Dep. Nat. Resour. Res. Bull.
offshore northern lobsters. U.S. Fish Wildl. (Fish) 16fic.98. , Spec. Sci. Rep. Fish $98.10 pp. ' Thomas, J.C. 1973. An analysis of the ' ; Smith, E.M.1977. Some aspects of catch /cifort, commercial lobster '(Homan43 amcricanus) biology, and the economics of the Long Island fishery along the coast of Maine August 1966 lobster fishery during 1976. NOAA.NMFS, v lobster Population Dynamics 143-L
4 through Dcocmter 1970. NOAA-NMFS Tech. Rept, SSRF-667. $7 pp. Ur.mann, J.R., R.A. Cooper, and K.J. Pecci. 1977. Migrations and dispersion of tagged American lobsters, Romarus americanus, on the southern New England Continental Shelf. NOAA Tech. Rep. NMFS SSRF.705. 92 pp. Wilder, D.O. 1953. The growth rate of the American lohstet (Hernarus arnericanus). J. Fish. Res. Board Can. 10:371 412.
.1%3. Movements, growth and survh'al of marked and tagged lobsters liberated in Egmont Bay, Prince Edward Island. J. Fish.
Res. Board Can. 20:30$ 318
. and R.C. Murray. 1958. Do lobsters move offshore and onshore in the fall and spring? Fish. Res. Board Can. Atl. Prog. Rep.
69:121$. 144 Monitorit.g Studies.1989
h Contents i i 1 Be n t h ic Infa u na . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
. In t rod u ct ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 Da ta Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 Multiple Regression Analysis . . . . . . . . . . . . . . . . . . . . . . . . . 148 Model Selection Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . 149 Cumulative Data Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 Species Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 Cluster Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 ,
Intertidal R esults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 Sedimentary Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 . General Community Composition . . . . . . . . . . . . . . . . . . . . . 151 Community Abundance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 Nu mber of Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 , Community Dominance . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 153 Domina n t Taxa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 Cumulative Abundance Curves . . . . . . . . . . . . . . . . . . . . . . . 159 t S pecies Dive rsity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 Cluster Analysis .................................. 160 D isc uss io n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 , Co n cl us io n s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 S ubt idal R esult s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 Sedimentary Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 l General Community Composition . . . . . . . . . . . , . . . . . . . . , 163 l Comm unity Abundance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 t Number of Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 Community Dominance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166 Do min a nt Taxa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166 Cumulative Abundance Curves . . . . . . . . . . . . . . . . . . . . . . . 174 - Species Dive rsity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 - Cluster Analysis .................................. 175 D is c u ss i o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 Co n cl usio n s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179 l Re fe re n ces Cit ed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179 [ 1
- .J
Benthic Infauna inirtxluction Unit 3 Intake construction (NUSCO 1987) and following Unit 3 start.up (NUSCO 1988a). This Annelids, molluscs and crustaccans inhabit sandy report summarizes results of sampling from intertidal beaches and soft. bottom subtidal arcas. September 1988 through June 1989. These organisms are an important food source for fishes (Richards 1%3; Moeller et al.1985; Watzin hfaterials and hiethmis 1986; Horn and Gibson 1988; Commito and Boncavage 1989), and their burrowing and tube. Infaunal samples were collected at three building activitics promote nutrient recycling from intertidal and four subtidal stations (Fig.1). The the sediments (Goldhaber et al.1977; Aller 1978; Giants Neck (GN) station is located beyond the Gaston and Nasci 1988). For instance, Zeitzschel areas expected to be affected by any environmental (1980) reported these activitics ruay provide 30% changes attributable to power plant operations; to 100% of the nutrient requirements of shallow. data collected in this area provide the baseline for water phytoplankton populations. assessing affects of naturally occurring climatic events. The intake subtidal station (IN) is located in addition, infaunal organisms are useful 100 m seaward of the Millstone Unit 2 and Unit 3 indicators of human impact on the marine intake structures and is exposed to potential scour environment; they are relatively sedentary (Reish produced by inflow of cooling water. The efnuent 1973) and respond predictably to disturbance subtidal station (EF), located approximately 100 m (Boesch and Rosenbutg 1982; Young and Young offshore of the quarry cuts, is exposed to increased 1982; Gaston and Nasci 1988; Regnault et al.1988; water temperatures, scour, and any chemical or Doering 1989). However, in temperate climates, heasy metal additions which might occur during infaunal communitics exhibit large fluctuations in power plant operation. The Jordan Cove (JC) and abundance and species composition in response to White point (WP) stations are located cast of the variable climatic conditions such as cold Millstone station, where plant induced water winters (Deukema 1979), storms (Boesch et al. temperatures are increased I to 4'F above ambient,
,1976), heavy rainfall (Flint 1985; Jordan and principally during ebb tide (NUSCO 1988b).
Sutton 1985), or to variations in the level of cornpetition and predation (Levimon and Stewart Sampling at each station included collection of 1982; Woodin 1982; Kneib 1988). Because of this ten 0.0078 m2 cores (10 cm diameter x $ cm deep) inherent variability, long. term studies are usually on a quarterly basis (September 1988, December l required before impacts of human activities can be 1988, March 1989 and June 1989). Subtidal ( separated from those which occur naturally samples were taken randomly within 3 m of each I (Holland 1985; Nichols 1985; Holland et al.1987; station marker by SCUBA divers. Each sample l Warwick 1988). was placed in a 0.333 mm mesh Nitex bag and l brought to the surface. Intertidal samples were t Because of their ecological importance and their collected at approximately 0.5 m intervals along utility as impact indicators, infaunal communities the water line at mean low water; samples werc l have been studied as part of the long-term placed directly into sampic jars. monitoring program at Millstone Nuclear Power l Station (MNPS) since 1%9. The 05jectives of in the laboratory, samples were fixed with a 10% l these studies have been to characterize spatial and buffered formalin / Rose Bengal solution and after temporal patteras and to identify changes in these a minimum of 48 h, organisms were Doated from communities which might be attributed to the sediments onto a 0.5 mm mesh sieve and construction and operation of the Hillstone preserved in 70% cthyl alcohol. Organisms were facility To date,our long-term studies have shown removed under dissecting microscopes (10x), sorted Iicalized impacts on infaunal communitics during into major groups (annelids, arthropods, molluscs, Benthic infauna 147
5 North 0: 1 mi N.ontic Doy g pg IN , wu, po,ng p 1 y GNl
,o n ~ Point \
Hg. t. Map of the Millstone Point area showing the kration or inraunal sand sampling stations (JCl, JCS = Jordan Cove intertidal and - subtidal stations; WPt = White Point intestidal station; El5 = 0.muent subtidal statkm; INS = Intake subtidal station; GNt, GNS = Olants Neck intemdal and subtidal stations). and others), identified to the lowest possible taxon 2. unit operational period (1980 - 1985). Should and counted. Oligochactes and rhynchocoels were power plant impacts occur they are expected to
' Ircated as taxonomic units because of the cause identifiabic shifts in abundance and species diiTicultics associated with identifying these richness and/or shifts in dominance structure ;
organisms to a lower taxonomic level. Organisms (Boesch 1973; Oden 1979; Persson 1983; Jordan that were too small to be quantitatively sampled by and Sutton 1985). our methods (e.g., nematodes, ostracods, copepods. and foraminifera) were not sorted from samples. Multiple Regression Analyses Orain size and sitt clay content of sediments (3.5 cm diameter x 5 cm core), taken at the time of Multipic regression techniques were used to infaunal sampling, were determined using the dry remove the temporal variation in community siedng method (Folk 1974)- abundance, number of species and the abundance of numerically dominant taxa that was attributable Data Analyses to fluctuations in sediments, reproductive or recruitment cycles, or climatic conditions. - This This report presents results from the period method was used to improve the sensitivity of September 1988. June 1989, hereafter referred to comparisons between data collected during the 2-as the 1989 report year. To identify changes that and 3-unit operational periods. Analyses were might be related to power plant operations, data based on t.verage quarterly abundance (In (x+1)) collected during 1989 were compared to prior 3- and species number collected from September 1980 i unit operational years (1986-1988) and to the through June 1989. Explanatory variables used in - the regression analyses were as follows: 148 Monitoring Studies,1989
+
{ i i t Precipitation - Daily precipitation records Sedimentary Parameters Sediment mean grain ! compiled by the U.S. Weather Bureau at the size and silt / clay content were obtained as part of Groton Filtration Plant, Groton, CT were obtained the monitoring studies and these quarterly values from June 1976 through June 1989. Values to the were included as explanatory va:iables in the nearest 0.01 inch were used as ' rain
- data. multiple regression models.
Water and Air Temneratures Ambient water Reproductive Recruitment Component.Infaunal temperatures (at the intake structures) and air organisms in the Millstone arca exhibit annual k temperatures (recorded at the 33 foot level of the peaks in abundance, often reflecting the seasonal Millstone meteorological tower) were obtained nature of reproduction and recruitment cycles or from the Northeast UtiSties Environmental Data periods of favorable climatic conditions. Spectral Acquisition Network (EDAN). Daily averages of - analyses of quarterly data showed annual cycles in 15 minute values were calculated for the period community abundance and number of species. To June 1976 to June 1989, account for this periodicity, harmonic terms (IErda and Salla 1986) having a period of 1 year, were Wind Speed and Direction Wind speed and included as explanatory variables in the regression direction (at the 33 foot level of the Millstonc models. meteorological tower) were extracted from the EDAN database for cach 15 min interval from in all, 32 variables were used during initial June 1976 to June 1989. These values were used model selection steps. These included two to calculate a wind index, which was wind speed sedimentary parameters, two seasonal / reproductive weighted accocding to wind direction. A components and seven climatic variables, each of navigational chart of the sampling area was used to which had four values representing daily and calculate site specific, wind directional weighting quarterly high and low extremes, coefficients. The directional weight ranged from O, when wind could not influence the station, to 1 AfodelSelection Procedurc when wind induced waves could directly affect the area. The wind index was then computed by The quarterly abundance and species number multiplying the directional weight by the wind were detrended using a linear regression model. If speed. Because the effect of wind was assumed to no significant linear trend was evident, residuals
, he cumulative, daily averages were derived using were created by subtracting the quarterly mean only wind index values greater than 0 (that is, from the nine year mean. A step-wise multiple when the wind was from a direction which could ~
regression was then applied to the residuals to produce wind effects). Identify explanatory factors and combinations of factors whose regression coefficients were Climatic Extremes (Deviations) - Additional significantly different from zero (Ps0.05). This i explanatory variables were created to represent level of probability was chosen to guard against unusual climatic conditions which occurred during fitting more parameters than could be reliably the samphng period. }ligh or low deviations (l.c., estimated, given the sample size The model that extremes) were derived for wind, rain, water and minimized the mean square _ctror and maximized L air temperature data and determined as the the t' was selected as the best model describing l difference between the quarterly mean or daily observed variability in community abundance, value and the 12 year mean (1977 89) for that numbers of species and abundances of selected quarter. Deviations based on quarterly means species. Covariance models including the factors l reflect the effects of longer term extremes (e.g., an found significant in the previous analyses were l unusually cold winter), while those based on daily then used to test for annual differences in values tend to remove the effects of shorter term abundance and species numbers. Pair wise t tests episodic events (e.g., storms). Daily deviations on means adjusted for covariate effects were used were averaged and also summed in each sampling to identify the significance of any interannual quarter to assess cumulative effects, changes in the abundance and speeles numbcr. Benthic Infauna 149
Cumulative Data Analyses Species Diversity l Changes in subtidal and intertidal sedimentary Species diversity at each station was calculated l cnvironments and infaunal community structure using the Shannon information index: l were quantitatively assessed using the Gompertz , ! growth function, a function which can describe n'. kiej j cumulative data that are not necessarily symmetric
- f about a midpoint (Draper and Smith 1981). This d where n,= number or indMdunis of the i specica. Natotal {
feature provides the flexibility to fit cumulative number or indMouais for all species, and s= number at ; data with or without an inflection point (s shape 4 *l'c" > versus parabolic) within the observational range. j The Gompertz function is as follows: An cwnness mmponent of diversity was calculated - as: C, a esp ( d e *) J where C,= cumulative sediment weight or species abundance at time t. a = total cumulative weight or abundance, il and a= "O Il
- NJ I 8"b >remis ma= l she thikal snamnum j kcation and shape parameters, trajecthtly (Drager and smith M 8% " " ###81l'88'W8% " b " * @l'I" N ,
"'8 0- Evenness ranges from zero to one and increases i as the number of individuals among species
~
l becomes morc' cvenly distributed. Diversity
- Fractional weights were used to construct calculations excluded oligochactes and' l cumulative sediment. curves for each. sampling rhynchomels (groups that sometimes accounted for .
station. A. 2 unit operational curve was over 80% of the total organisms) because they ; constructed by pooling quarterly grain site were not identified to species. This b!as must'bc fractions in cach 2. unit operational year recognized in any interpretations of plant impact (19801985) with years serving as replicates. For based on this index. the 3. unit period, quarterly weights were also pooled, but years were considered separately. Th Cluster Analyses Oompertz function was then fitted to data for the -
- 2. unit operational period and= cash 3 unit Cluster analyses techniques were based' on operational; year using non linear regression methods. Two sample t. tests were used to average abundance over the 2; unit period (1980-
- 85) and on annual abundances in cach 3. unit year compare the n and parameters derived for the *
(1986-89). . Similarity in the abundances of taxa
- 85) curve and cach 3 unit operational over stations / years was based on the Bray.Curtis. .
3 3 similarity coefficient calculated using the formula:. In this report, cumulative abundance curves were constructed, by plotting cumulative percent' abundance (ordinate) versus the natural logarithm b ' h I"'8 bM of a taxon's rank (abscissa). Comparison of these curves (k dominance curves), have recently been hW'I I where X*= abundance or altribute I at entity j and i suggested as a means of assessing the structure of' Xa-abundance or atmbute i at entity L macrofaunal mmmunitics (Warwick 1986; Warwick ! cti al; 1987). The 00mpertz function was then Based on these similaritics, a clustering algorithm- ] used to derive parameters describing cach curve incorporating a flexible sorting strategy (Lance and - , and' two sampic t tests performed to comparc Williams 19M), (0 =-0.25) was used to+ form-
~
curves for the 2 unit- period' and each 3 unit station groups at, decreasing similarity and the , operational year, results are presented as a dendrogram; .g a 150 Monitoring Studies,1989 l f
intertidal Results
+ .
Sedimentary Environment in 5%$,y Inter:idal mean sediment size during the 1989 l'" 3 report year ranged from 0.36 to 0.47 mm at GN, j. .! from 0.31 to 0.60 mm at JC and from 0.43 to 0.54 d som at WP (Fig. 2). As in all past years, sediment grain size exhibited greater temporal variations at g '", g ,f ,, JC than at either GN or WP. Quarterly silt / clay values terrained below 0.5% at all stations except '" , , 3 g' ", , ' " ' "4 4 " for September 15 t JC.- Quarterly grain size u d silt / clay vs ! both GN and WP during i 1989 were typic,J G otose obtained throva our study. At JC, mean grain size eMiw less '" ' t temporal variation than prior . year:.. rp,1 the ,, Qf$,y l December 1988 and June 1989 sedime:as were among the finest collected at this station. Silt / clay ['" ! { ; nlues at this station remained low throughout p.. / ) .! 9 89-l ,, 2 i g . Cumulative sediment curves for each w ,./ , operational year (1986-1989) and a composite ,J curve for the 2-unit operational period (1980-85)
- - ^/\%f\
were constructed to assess temporal iluctuations in sediment composition (Fig. 3). Based on t test comparisons of _the curve parameters, the , , sediments at WP and GN during 1989 were not ,,, , significantly different from any previous year At in
@sW;;n-lj J C, however, sediments during 1989 were '
, significantly finct from those observed during 1980- l'" ?
85, due to the increased percentage of finer j . >. .. ! grained sands in 1989, a pattern evident since 1986. g- 8 General Comraunity Composition ., V% \W .
^
Fifty five taxa and 4,311 individuals were ' " " " * * * ~ " - " ' "' - - -- represented in the 120 samples collected at the l three ia.tertidal stations during 1989. The JC community had the greatest number of species (45) Ig. 2. Quanerty mean grain size (mm) and siit.ciay content and individuals (2,546), whereas GN had the least (%) f sediments at Mi si ne intertid I stations from SCPtember 1979 June 1989. (15 species and 818 individuals) (Table 1). Polyrhactes accounted for the majority (44-73%)of speeles at all stations and for the majority-of relatively numerous, but accounted for only 4% individuals at GN (75%) and WP (74%). and 1% of the individuals, respectively, Oligochaetes accounted for 73% of the total e Individuals at JC. Rhynchocoels were a numerically important component of both GN During 1989, the number of taxa comprising (22%) and WP (14%) communities, while at JC major infaunal groups was typical of that over the 4 molluscs (24%) and arthropod (31%) species were 3 unit and 2 unit operational periods. At all stations however, the total number of organisms Berthic Infauna 151
1
% 7 : , period. Total numbers of rhynchocoels at GN and
.,um WP also declined in abundance in 1989 relative to
?,";; 10P" the 2-unit and 3-unit periods, hC, '..E f "' ' " " ' * "
Community Abundance s li aa - r y Quarterly mean intertidal abundance (per core) ' and multiple regression predictions are presented in Figure 4. Macrofaunal abundance during 1989 ranged from 2-33 at GN,17114 at JC and 12 37 at s W P. Periods of highest abundance occurred in
-i -i 6 4,, i i e s September (GN and JC) or June (WP) and lowest in March (GN. and WP) or December (JC).
- Multiple regression analyses revealed no significant - -
m cmc g Y.~ trends at any intertidal station from 1980 through h, {%" g;, ,*,; Awe 7 , 1989. When compared to previous years,1989 average density at GN was significantly lower . 5 (Ps0.05) than 1987 and 1988 and lower than 1985 [ ,, and 1987.at JC, At WP, the 1989 abundance was y not significantly different from any previous year.
) g/ At all stations, there was no significant difference --
8" between average community abundance in the 3-unit period and that observed in the 2 unit period.
-4 "' *
,,,6 * * *
- Number of Species
* : 0
- Number of speeles per core during 1989 ranged -
;gt,rg, from 1 to 6 at GN, from 5 to 11 ut JC and from 4 -
. g ,, L, to 6 at WP-(Fig. 5), Periods of highest species v
%, '.',14'"
E%.'d , number were the same as- those of. highest ,g [/j, community abundance; higher values' occurred in r a y p' September or June and lower ones in March or - December. No significant trend in average
) ,/ quarterly species number was evident at - any d, intertidal station over the 1980-1989 monitoring period. Ablotic variables accounted for 50% '
(GN), 72% (JC) and .35% (WP) of the total
.. ..' ' 8 3
- 5
,,,,,,3 variation in species number. At JC and WP, there 1 was no significant difference between the mean Fig. 3. Cumulative curves based on fractional weights of number of species in 1989 and any previous year, sedimenta coHected during the 2 unit (19841985) period and At GN, the 1989 value was significantly lower than each 3-unit operational year (1986-1989) at Millstone intertidal 1987 and 1988., For all stations, no significant difference in species number has occurred between
~
within each group in 1989 was generally lower. For example, the total numbers of polychaetes ranged from 5(M (JC) to 697 (WP) during 1989 versus 921 (WP) to 2,300 (JC) during the 2 unit period and 709 (WP) to 1943 (JC) over the entire , 3 unit period. At all stations, oligochaetes exhibited the greatest decline in total numbers in 1989 compared to the 2 unit and overall 3-unit ; 152 Monitoring Studies,1989 I
c.,-
]
TAllLE 1. Number of species (S). number of individuals (N) and the contribution to the total individuals (%) for each major taxon collected at Millstone intertidal stations in 1989 with means and coefficients of variability for 3-Unit operational years (1986 89) and 2. Unit operational years (1980 85). 1989 1986-89 1980-85
$ -a ti 3~ MEAN E' hjf,6N, CV MEAN CV MEAN CV Olants Neck
- Polychaeta - 11 733 614- 75.1 18 18.4 1339 26.7 18 11.2 ;1375 - 183 Oligochaeta . - - 15 1.8 - *
- 297 34.0 - - - 278- 31.5 Mollusca 2 133 2 0.2 3 273 4 39.5 . 3 413 .7 373 Arthropoda 2 133 7 0.8 3 9.1 9 423 8 183 25 28.4 1 Rhynchocoela - - 180 22.0 - - 189 11.8 - , 410 28.5
' Total 15 818 24 17.2 1837- 24.4 29- 12.8 - 2095 12.8 Jordan Cove Polychacta 20 44.4 - $04 19.8 22 5.5 1943 32.4 19 ' 7.7 '2300 18.4 Oligochaeta - - 1850 72.6 - - 7149 30.2 - .- 9099. 23.0 Mollusca 11 24.4 101 4.0 7 30.8 52- 31.6 8 7.4 170' - 64.4 Arthropoda 14 31.1 37 1.4 13 8.3 56 15.1 - 15 12.4 303 453 Rhynchocoela - - 54 2.1 - - 74 11.0 . .
31 39.2 1 Total 45 2546 41- 4.0 9274 26.9 .' 43 . 5.8 ' 11903 - l8.2 _, WhHe Point Polychaeta 14 63.6 697 73.6 12 9.1 709 40.1 17 9.0 921 17.9 l Oligochaeta - - 91 9.6 - - 102- 32.8 - - 308 30.2 l , biollusca 5 22.7 24 2.5 3- 31.1 9. 62.0 '3 25.0- 6 44.6 ' l Arthropoda 3 13.6 5 0.5 5 183 . 8 13.5 13 28.6 7 21 3 Rhynchococia - 130 13.7 - - 3% 38.2 - - 504 17.0 Total 22 947 ' 20 7.4 1223 18.1 22. 11.7 1744 14.2
*C.V. = (Standard Error /Mean) x 100 Community Dominance - were the numerically dominant taxa.at JC, but ~
' because of: the l high : relative abundance of Oligochaetes ranked sixth at GN, first at JC and o!Igochactes at this station, ' these1 organisms fourth at WP in 1989; thynchocoels ranked third at comprised only 17% and' 3% of =the totals, GN and WP and sixth at JC (Table 2). As for. respectively-species at GN and WP, . the = polychaetes, Leitoscoloplosfragilis and Paraonisfulgens were the - Intertidal macrofaunal communities during 1989 numerical ' dominants. Leitoscoloplos fragilis . exhibited some differences c in the relative accounted for 30% and 32%, and P. fidgens for- abundance of the numerically dominant taxa at all- ~ .
23% and 34%, of the total organisms collected at . sampling stationsi At GN, the relative abundance - i GN and WP, tespectively. oligochaetes comprised "of Leitoscoloplos fragilis, Paraonis fulgens andJ 73% of the total organisms collected at JC; the . thynchocoels was higher, and that of oligochaetes,- 1 polychaetes, scotecolepides viridis and capitella spp. Hediste diversicolor and Polydora lignilower in 1989 _; i Benthic Infauna - '153 i t
$tetion 04 ANT) N(Ca( 9(f(RhM > $ elsWe OtAN1$ll[CW INT (RTCAL 9 8 = 0 60 . 98*0M:
g- - g ,, l- (. l-
- s ..
- g. .
- 4. j.
. . ?
e-
.', ~
us>, um ussi urn um uPe. um um ussi um uPee us= um u*ei um um isse. um um u*e> uses um ' Stot6an JD#D8N C(NL #dTERhDet : ( Station JO#tdN Cf'N! DetERTitet
. a . oat ,. n i . o.n g ,
. . g .9 .;b . ..
p ., [" >. g-u (L. - - ( .. g. t, [fp g, '.
+
.' ) ;, ,
.. \
i MPFS MP90 SEPSI SEP9J $179) SEPs. SEPe51(Pee MPe7 MPeA SEPe9 $[P79 MPG 4 MP91 ELPe2 MPS) $[PG. MPei $tPS6 MP471(Pet MPG)
- a
..m e., - ,, 1r,-,m.. I
.i.on . - . eas . .. j i
.~'
g l. ' L ' s
- o. .
MP79 $tPeo SEP61 SEPS2 MPS) 4(PG4 WP66 SEPe6 MP97 Stree $[P99
$[P79 &[Pgg MPgt $EPS2 mpg) 1(Pg. $(PS$ ICP94 MPl? MP99 1(PM ' l Fig 4. Quarterly mean abundance and multiple regremion Fig. s. Quarterly mean species nutnber and multipic regression -l predictions for Millstenc intertida1 communities from September predictions for Millstonc intertidal communities from September
'j 1979 dune 1989.
1979 June 1989. than in 1980-85. At JC, reduced dominance of ' Dominant Taxa-Scoleculepides viridis and Hediste diversicolor was - a evident in 1989 relative to the 2 unit period (Table - 2)i At the WP station, the dominance of P.fulgens Temporal changes = in the' hbundance of thec numerically s dominant' intertidal . : taxa'. 'were j q and L. fragilis in 1989 increased relative to 1980-85, while the percent contribution of oligochaetes examined using the same approach described for. ] community abundance: trends wereLidentified
~
and rhynchocoels decreased- - Over 3 unit years based a on 3 -linear ? regressions and-? multiple - (1986-89), the percent contribution of each taxon- regressions, and analyses of covariance and t. tests - i except oligochaetes .was ' consistent with those were used to compare abundances between 3. unit - obtained during the 2. unit period.- and 2 unit operational years. 154 Monitoring Studies,1989
.i
-j
- . . = ,
l b TABLE 1 Relative abundance (%) and cocmcient of vanabihty (CV) for each of the ten most abundant taxa collected at the Millstone . Intertidal stations during 3.ljnit operational years (19861988) and pre. operational years (19801985). i 1989 - 1%88 ' 19485 i Giants Neck ~~ @ @ . E' S E Leitoscoloplasfragild 29.1 23 3 4.8 - 15 3 5.0 , Paraords fulptr -- - 23.1 11.6 - 28.4 13.6 - 17.1 Rhynchococia 22.0 9.9 2.4 17.7 8.2 Scolecolepides viridis 14.5 15.5 20.4 15.0 9,5 Microphthalmus scselkowil 4.8 2.1 100 0 13 ; 28.0 . Oligochaela 1.8 19.4 5A- 11.9 14.7 .t Capliclla spp. 1.0 - 3.0 42.4 6.9 _ 15.2 lledisse dinrsicolor 0.6 2.7. 43,6 2.1 36.2 Polydora ligd 0.6 2.5 42.2 23_ 26.9 - 1)psplo cicputt 0.1 2.1 - 71.5 13 37.3 Jorden Cove Oligochacta 72.6 77.0 1.7 70.6- 2.8 s Scolecolepides viridis 6.6 1A 14.1 10,8 11.1 , Capiscila spp. 2.6 2.6 27,8 2.0 24.6 - Microphthalmus sciclkowli 2.6 1.1 $0.0 1.1 47.6 Ilediste diwrsicolor 2.2 9.7 8.0 5.3 . 28.1 ' -! Rhynchocoela 2.1 1.7 7.2 . l .2 . -29.0 Octruna ' l.6 1.1 233 1.7 47.8 Polydora ligd 1.4 1.7 ~ 15 3 2.l 25.6 ; Etapmc Acbes 13 1.0 _ 100.0 1.0 / 61.2 :
. Gammaruslanrencianus 0.4 1.2 -- 56.2 1.8 64.6 l
White Point
* ['araonisfdptr 34.2 15.1- 2.2 ' 15.6 8.8 Lcisarcoloplarfragilis 32.1 13.5 16.2 20.2 ; 4.7 Rhynchocoeta l
13.7 33.0. 19.2 29.4 . 5.5 Oligochaeta 9.6 7.9 9.5 15.2 10.1 Strepta9l/n arenac 3.I 4.9 65.0 - 4.7 11.5- , i Erogme hebes 1.7 . 1.2 -- 26.8 = 1.4 ' 20.4 '4 Parapionosyllis longicirrata 1.0 23 ' 55.4 - 1.7 23.6 > Capitella spp. 0.4 1.4 36.5 2.7 M.9 i Polydova ligd - 0.2 1.2 $5.9 2,4 33.4 Scolecolepides viridis 0.2 : 2.0 45,4 :23; 39.5,
'C.V.= (standard Error /Mean) x (100) organism at JC throughout the monitoring study; i Oligochaetes although less abundant at GN and. WP, this group .;
has consistently ranked among the top numerical- , These short lived, deposit feeding annelids are - dominants since 1980. , commonly abundant in orga nically enriched littoral and shallow-water marine habitats where they feed Oligochaetes ranked first at JC, fourth at WP-on the microbial populations that colonize organic and sixth at GN during 1989 (Table 2). . Quarterly :
. detritus (Soulsby et al. 1982; Hull 1987). abundance (per core) ranged from 0 to 2 at GN,7. ,
Oligochaetes,have been the most abundant to 65 at JC and' 2 to -6 at WP '(Fig. 6a.c). Although densities of oligochaetes have typically _ , Benthic Infauna 155 i of
"" during the 3-unit period was not significantly si = c= n e ata x different from that observed in the 2 unit period.
DI%** a. At JC, the average abundance of oligochaetes in 1989 was significantly lower than that in 1985,- b.- 1986 and 1987; however, there was no significant -i E
- difference in the average number of oligochaetes between the 3-unit and 2-unit operational periods.
I .. ' '
- Rhynchocoela j .
, Rhynchocoels inhabit both sandy. and rocky
'u,,,u m us. u m, uso um usu um me., um um shore environments. Species that live in mud and sand are excellent burrowers and able to inhabit-som m,.cmt wing shifting sand environments - (MacGinitie : and ow" MacGinitie 1968) These organisms ranked first at b'
GN and WP during the 2 unit period; and first at l,, . . WP and fifth at GN (Table 2) during 3 unit
; ,,.. , , . , operation, t= .
! Y .
, in 1989, rhynchocoel abundance per core ranged i
)" *
~.
from 1 to 8 at GN and 2 to 7 at WP (Fig. 6d c).
- Quarterly values during 1989 were within the range of past years and no.long term trends were evident -
i _ . . . . .__ at either station. At both stations,' the average un. um um um s:m um um um um um u* abundance in 1989 was not sigr ificantly different l so m. mic.o.m.atn a from any prior year (except 1980 at GN), and - i em abundances in the 3 unit: period were not significantly different from those obtained in the 2-l,,,, unit period, i l~ l Scolecolepides viridis '
, Scolecolepides viridis ~ is n ' large polychacte commonly abundant in intertidal sand (Wells and '
Gray 1964) and is most frequently found in areas
'ufum um uen um um we2um um um um of reduced salinity (Smith 1964)._ Adults inhabit a '
mucus-lined tube and feed on surface detritus, = Fig. 6, Quarterly mean abundance and multiple regression diatoms, filamentous - algae . and nematodes Predictions for selected dominant organisms comprising (Sanders et al.1%2) Scolecolepides viridis ranked Millstone intertidal communities. third at GN and second at JC during the 2 unit exhibited wide temporal variations in abundance in past years, values obse ved in 1989 were among the in 1989, Scolecolepides viridis ranked fourth at lowest recorded during this . study. Linear regression analyses, however, revealed no GN and. second - at JC (Table 2). Average . 1 abundance ranged from 1 to 5/ core at GN and significant trends at any intertidal station, from 2 to 10/ core at JC (Fig. 6f g) with highest l Multiple regression analyses accounted for over abundances occurring in SeptemDer and June, 50% of the temporal variation at ON and WP, but Regression models removed 68% (GN) and 61% l only 18% at JC. After adjusting for variation, (JC) of the temporal variation in abundance, most average abundance at GN and WP in 1989 was not of which was due to the high, but repetitive significantly different from any previous year. In seasonal reproductive / recruitment cycles exhibited
- - addition, oligochacte abuitdance at these stations L 156 Monitoring Studies,1989
Stalign GANTS NtCW WT(KnD4 $ tete.a. CIANTS NCCM INfCRilDAL
. . , _ . ...W.
- e 8 . o rs d. es.0u f. - )
6 b .ro k.se I 6 . e g .g . .
$tsts streo stest stre; ups) MPs. usas stPas ure, stPgg $(P99
$[h P'9 SC,90 tiP01 SEPO'2' LEE 5
[\ . 3 SLPt. StiS5'ltpet $tPS, SEsos 5(Pe9 -
$14 Hon: WDW7( POWT INf(RTID4 ' $tetion: JOADAN CO/C INTERT10AL n*,.cnw 4 -
A..k brW rWw g..
~
Aa e 0.15 ' C. R a
- 0.6 t -
tam som -- r
,E E 2 l E
g= g= .,- .. , a * *
- 5 . .
I- .. y ,
/ . *
. . . i u P ,. u m we., u m u m uP.. uen u,. u,., uP u s , um uP., usu u m u,..neo uP
.P u,., u, um i Fig. 6. continued. statiaa: JoaQAN COVE teftRf% .*
m n.=.n .u, by this species. No significant long-term trends ,
''3
- have occurred at either station. At GN,1989 g"" ,
abundances were not ilgnificantly different from p
- any previous year, while at JC, .-1989 was
- g .. , ,
significantly different (lower) from only 1983, a
- - ' Average abundances of S.+/ridis at each station I during the _3-unit and 2. unit period were not; #" -
l- significantly different. . p , . 1 Hecliste cliversicciar ""'"*"'""~"*"'""'""'""'""**"'" Fig. 6, continued. .. Hediste diversicol r is found in near shore waters . L from the North Atlantic and North Sea to the consistently low (1/ core)'(Fig. 6h).' Although no Mediterranean (Gosner 1971). This omnivorous . significant trend was evident over the monitoring _
' polychaete is frequently abundant in nutrient rich - period, the mean abundance of H. diversicolor:in ^
areas and has been consi_dered " opportunistic" and 1989 was significantly lower than that observed in
-an ' indicator of pollution" (Hull 1987). Hediste . cach of the last_ five years. However, average -
diversicolor was' numerically dominant only at JC, abundance in the 3-unit period ' has not been s I where it ranked third over the 2. unit period and . significantly different from that observed in the 2 ; second during the 3 unit period (Table 2); unit period. During 1989, Hediste diversicolor ranked fifth .; at JC (2% of the individuals Table 2.). Hediste~ diversicolor abundance throughout 1989 was ' L Benthic Infauna 157 a s
i only 1980. For both stations, average abundance q si.w cats.o mn=rm - of P. fulgens in the 3 unit period was not l7'""f*~ 1. significantly different from that observed in the 2-unit period. I E Leitoscoloplosfragilis 1,,,
- y ., , , Leitoscoloplos fragilis is a relatively large a= -
,, polychaete capable of ingesting large sand grains and rapidly burrowing through loose, unconsolidated sediments. This species is' well
'uel. um us., um'ne.1 us.. men um men u='um adapted to irthabit areas of sediment instability (Myers 1977; Rice et al.1986) and, like Paraonis si . 1( po.<v iunnim fulgens and rhynchocoels, is typically dominant at-r=~ A 9~ only the exposed sandy beach stations (GN and_
WP). Leitoscoloplosfragilis ranked second at GN : [. and WP during the 2-unit period and first (GN) p and third (WP) during the 3 unit period (Table 2). g. a In 1989, quarterly abundance of L. fragilis ranged j ,, *
- between 0-11/ core at GN and 216/ core at WP-
. (Fig. 6k 1), with values at both stations exhibiting i.
** . * * Siet a. Ceant5 N(CN NT( 1%
uer, u m v.. usu neu w.. u u s w u uen u m us w , o.,.
. . . o.s. k, <
Fig. 6, continued. g** E Paraonisfulgens l~ a . g . . Paraonirfulgens is a deposit feeding polychacte W ,, , , that inhabits clean sandy areas (Whitlatch 1977; . ,
'Strelzov 1979) from Maine to North Carolina ,
(Gosner 1971). This species consistently occurs at ' , , , ' , , *,,,,, y,,, y,,'f g,, g, ,,,,/ ,w ,,,, ,,,,Q GN and WP stations which are moderately exposed, well drained sandy beaches. Based on == average abundance, P.fulgens was among the top w . . r.,. four numerical dominants at GN and WP during "'""' I' the 3-unit and 2 unit operational periods (Table g*' 2). p In 1989, this species ranked second at GN and I~ y first at WP, with quarterly abundance per core s . ranging from 1 to 10 at GN and 2 to 21 at WP ** , (Fig. 61 j). Highest quarterly values were observed ,' *
- In June at both stations, with values exhibiting a , , .
~
f, ' stronger seasonal pattern at WP than at GN. No ""' "= ***' xm u m ** **a $i= *
- u*a ***$
significant long-term trends were evident at either station.' At GN, the mean abundance of P.fulgens U8' ' """"*d' in 1989 was not significantly different from previous years; at WP,1989 was different from 158- Monitoring Studies,1989 i' e
?
b strongseasonal fluctuations. Explanatoryvariables . accounted from 54% (GN) to 86% (WP) of the temporal variation because of strong seasonal l / cycles; however, no long term trends in abundance were evident at either station over the monitoring y y
// '
/ /
period. At GN. aveinge abundance in 1989 was it' significantly different from only 1988; however, l ,,. abundances in the 3-unit period were significantly g s'**a euwmm higher than those in the 2-unit perkx!. At WP, the '{jy'y#p 1989 annual mean abundance was rlgnificantly ggy higher than those of 1985 1987; however, there was , no significant difference between 3. unit and 2 unit 6 i, i a periods. Cumulative Abundance Curves - Cumulative abundance curves were used to compare the dominance structure of infaunal' E communities in each 3. unit year with that observed over the 2 unit period. Data were fitted to the {p .. Gompertz function (see Materials and Methods j 5;^j;.,7 C"** Section) and t tests used to evaluate the @:ky' differences between the parameters derived for IU':277* cach curve. For intertidal communities, the top , ranked taxon accounted for 30-45% of the total
- yyg ,3 % g _2 3 individuals a; GN,60-90% at JC and 30 65% at WP (Fig. 7). The gradual slopes of all JC curves '-
+e.
relative to other stations, reflects the high numerical dominance of one taxon (oligochaetes). b - The flatter curve in 1989, relative to prior years l g (( . was due to reduced abundance of co dominant species (i.e., Scolecolepides viridis and Hediste 9
}=
/p[
diversicolor). This shift produced significant differences between the 1989 curve and those of g 3
/
, 5;'2",,,"f,"""**
l the previous three years (1986-88); however,1989 @:ky* - l was not significantly different from the 2 unit 3:E%"'*" l period curve. The WP community structure during , 1989 was significantly different from those of 1986 6 i ,,g
- i g
and 1987, when rhynchocacis accounted for 60-70% of the totalindividuals, but not from 1980-Fig. 7, Cumulative species abundance cutves based on the top
- 85. At GN, community structure in 1989 differed ten numerically abundant organisms coliceted during 2.unii only from 1986, when very high abundances of (t9801985) and ror each 3 unit operational year (1986-1989) at Scolecolepides viridis were collected. As at other Miiist ne intertidal stations.
stations, there was no difference between 1989 and the 2 unit curve. obtained at WP. At GN and WP, values for . diversity during 1989 were within ranges observed Species Diversity durin8 the 2 unit operational period; low overall diversity of these communities has been consistent throughout the monitoring period. At JC, H' and in 1989, H' and J were highest at JC, averaging J valu s in 1989 were higher than previous years, 3.3 and 0.8 during the year (Fig. 8). Lowest average diversity (1.5) and evenness (0.5) were due primarily t the decreased dominance by Hediste diversicolor and Scolecolepides vmdis. Dcnthic Infauna 159
i i
' unit operational year were considered separately.
t
.l
$1ATCN. CIAfff$ N(CM m,, gn. ...) : The dendrogram summarizing results of the .c r twass v) F --) cla sification was divided into two primary groups which linked at low similarity (12%); Group 1 L contained all WP and GN years nn:1 Oroup 11 all-
' ,- ,jN \ ~
JC years (Fig. 9). ' The low spatial: similarity i i l reflected the consistent difference in the kinds of
\" organisms and their ':bundances at GN and WP -!
. versus JC, The formvr twc stations are dominated
;--o ,,g_.., _.-+. . 9 ..4....... -l .
; g, ,7, y.
Paraonis fulgens while the latet is dominated by o.6 .u, mi ,e ,u. ,m ,a. w sm .m oligochaetes, Scolecolepides viridis, and Hediste *
.. diversicolor.
41Aficet JORDAN C0kt DhTRSTY (H) { ~ * ) i 3 [dNNtl$ Q)(~
- a-)
ID
- I to -
f m.
'N ,
M *- so - so - _ > 1
- yo , A l a
j... q .-. 4 ... q , . ,p ~*....-+"~~t' j l- . e 1
,.. , , - . . . . , . .- ...c,.,... t R, ' * % '* * *$' * '* %
stueer mit FONT . 0**" ("H ' - - ' * ) Fig. 9, similarity dendrogram twed on mean species abundance 3 NSS UM* * 'I during the 2 unit oarational period (19801985) and in cach 3 A ,s L unit operationa. W r (19861989) for Millstone . Intertidal IN communitics. : i if\p, + -{ i Group i further divided'into a' subgroup of 2 ~ i unit periods for GN and WP (Subgroup A) and n :
;- ,.-.-.+-+--.p...+"' subgroup containing 1989 collections at. both-
.._...4.s..,..
stations (Subgroup B). Collections: within
" Subgroup A were characterized by high numbers of mo iai i.u i=3 in, ins i .. in, in. .i oligochactes, Leitoscoloplos fragilis, Paraonis lig. 8. Annual mean species diversity (11') and evenness (J) 1 fulgens and loweT numbers of rhynchocoels retative -
i 1 su for Minstone intertidat communities sampted from to those collections within Subgroup B.-.' Within September 1979 to June 1989 Subgroup A, the ON _1986 and -1988 collections separated from other years due to the unusually Cluster Analysis high abundance of Scolecolepides viridis (1986) and L. fragilis (1988). Cluster analyses techniques were used to assess temporal and spatial patterns In the kinds of Group II, containing JC collections, showed ' organisms and their abundance in the 2 and 3. unit chaining of years rather than paired groups. This operational periods. For this analysis, abundances type oflinkage reflected temporal shifts in relative for each taxon were averaged over the 2-unit abundance among a similar suite of dominant taxa - period (e.g., JC.8085), while abundam.cs in each 3 .(e.gi, oligochaetes, Scolecolepides viridis, L Hediste 160 Monitoring Studies,1989
1 E diversicolor). The 1989 collection linked at lowest to the low abundances of oligochactes, ' similarity to ot%cr years because of the low Scolecolcpides viridia and Hediste diversicolor, taxa i abundances of these previously abundant taxa. which have been highly abundant at this station in : past years. All measures used to examine i Discussion commurdly structure in 1989 (i.e., cumulative abundance curves, species diversity, and cluster Intertidal macrofaunal communities during 1989 analyses) reficcted the lower abundance and more exhibited spatial patterns in abundance and the even distribution of ?ndividuals among taxa. distribution of the numerically dominant organisms Because the dominant species at JC are generally that were consistent with prior years. Macrofaunal small deposit feeders ' that are abundant in abundance and species numbers were highest at organically enriched habitats (Soulsby et al.1982; JC, as in all prior years. Oligochaetes were the Davey and George 1986; Hull 1987; Majecd 1987), numerically dominant taxon at this station during observed changes in the sedimentary environment 1989. The GN and WP communities exhibited are the most likely cause for the shifts in the lower abundance and species numbers than JC and, macrofaunal community, at both stations the polychaetes, Lcitoscoloplos fragilis and Paraonis fulgens characterized the Sedimentary characteristics at the JC site are fauna, potentially influenced by a variety of factors. This station is a semi protected beach but exposed to Like other temperate infaunal communities the strong southeasterly winds produced during (Green 1%9; Croker 1977; Holland and Dean storms. . Variations in the intensity and frequency != 1977; Whittatch 1977), those inhabiting the of storms could produce annual variations in the Millstone area are believed to be strongly sedimentary profile of this beach like those influenced by physical environmental variables, observed in this studyi Along with these natural Spatial differences in structure and abundance like events, the potential impact of 3 unit operations , those observed in our studies have been reported (m JC must be considered, particularly because the l along gradients of increasing exposure (Eleftheriou change in sedimentary characteristics at this station and McIntyre 1976; Withers and Thorpe 1978), in - generally coincided with start up of Millstone Unit particular, wind induced wave scour (or lack 3. Because the station is located in a cove thereof) has been frequently cited as a major adjacent to the Millstone facility, direct impact due q
, structuring mechanism for intertidal macrofaunal to 3-unit operations would not be' expected, f communities (Maurer and Aprill 1979; Tortellotte However, plant related sedimentary changes could and Dauer 1983). The spatial differences in occur if the combined 3-unit discharge alters tidal community structure and abundance between our circulation or alongshore current . patterns. l Intertidal stations during 1989 are believed to be Changes in these circulation patterns could alter the result of differences in natural factors, which beach crosion and accretion patterns, which in turn structure these communities, and not to power might produce changes in- local ~ infaunal !
plant construction or operation, communities like those observed in 1989. ' Temporal changes in the sedimentary In 1989, infaunal community abundance. number - environment - and the macrofaunal community of species and dominant taxa at the potentially observed in 1989 were most pronounced at JC. impacted WP station and GN reference station . Sediments during this year were significantly. were similar to prior years. .Infaunal communities ! different from those observed during 1980-85, due were dominated by Paraonisfulgens, Leitoscoloplos i to the increased percentage of fine sands and fragilis and thynchocoels, taxa that dominated these continued low silt / clay content. In addition, algae communities throughout the 2-unit period. Year-and celgrass detritus, which in past years formed a to-year' differences in these communities. have thick mat that covered sediments from the low to typically involved short term shifts in the rank- l mid intertidal zones, was absent during 1989.- position among the numerical dominants. Like JC, ! Macrofaunal abundances at JC in 1989 were near these shifts appear most likely a response to I the lower end of the 10-year range, due primarily changes in local sedimentary characteristics. For i Benthic Infauna - 161 I w
instance, at WP, reductions in the abundance of so . the burrowing deposit. feeder L. fragilis, a species E4" swo= tmoria which prefers fine to medlum sands (Rice et al. gmo , 1986), occurred soon after sediments at this g we stations became coarser (NUSCO 1989) Also at this time,the abundance of rhynchococls increased. in ie (# V**~*"
# fax, +
In 1989 (and 1988), grain size and the abundances yn
- W Y: I N- .k' -
of the above taxa were similar to those observed E u. prior to 1986. in.e -s~s w Coneluslons ",,,,,,,,,,,,,,,,,,,,,,,,,,,,,,#,,,,,,,,,,,,, The abundance, species number and composition of intertidal infaunal communitics during 1989 "'- were similar to those observed during 2-unit and 3 Ea' swouw unit operational years. Differences in the communitics at these stations are believed to result { x' i'"- f N Ii/y . /s from natural differences in the degree of exposure '" .m A ,, . ..gj k.'I / \.' S-s to wind and wave action and not to power plant operation. Temporal differences in the abundance {" of some numerically dominant intertidal taxa were g" cvident at the two potentially impacted stations " during the study and probably were a response to " bA s observed changes in local sedimentary ",,,,g,y,,, ,,,,,,,,,,,,,,,,,g,,,,,,,,, environment. These changes could reflect either natural events or power plant impacts, but their =' exact cause can not be detctmined at present. E*" swe cema q que Subtidal Results 28"
,o ys A. A,,. .,
,qqsq ...,
s Sedimentary Environment 1 Meen quarterly grain size and silt / clay content N" for subtidal stations from September 1979 to June 1989 are plotted in Figure 10. During 1989, l""' # w sediments were comprised of medium to coarse "ves um un, um um um um um um um um sands (0.44 0.62 mm) at EF, medium sands at GN (0.26-0.36 mm), and fine to medium sands at IN (0.17 0.25 mm) and JC (0.210.26 mm). Sediments P' at EF were again coarsest in 1989, a trend first k" h(
)\ ,\/
- Vw' V //l/
observed in September 1985. At JC, grain sizes 5'"'" f , , .a ,.. . . during 1989 remained lower than before 3 unit \...e operation. Mean grain sizes at GN and IN during 1989 were within the range of those observed $" during the 2 unit period and in other 3-unit years. N "' Percent silt / clay during 1989 was lowest at EP (1-l"" 2%), intermediate at GN and IN (6-10%), and highest at JC (1315%) (Fig.10). Silt / clay within ven ue. us., usu um um um um um um uen EF sediments remained low relative to the 2. unit I operational period while those at JC remained Fig.10. Quarterly mean grain size (mm) and sitt. clay content high. At IN, silt clay values during 1989 (%) r sediments ni Milisi ne subtidal stations from september 19794une 1989. ! 162 Monitoring Studies,1989
were lower than most observed since March 1983. '* p>* Silt / clay content at GN during 1989 was at or c%. jf'
/
below the lowest level observed since 1980. g ,, r g!,"u; c,0. . in. 5 The 1989 cumulative sediment curves at three of the four subtidal stations were significantly b" different from those based on 2-unit operational E data (Fig.11). At EF and IN, the 1989 sediments were significantly coarser than those obtained f ,,
/
- g
- V during the 2 unit period while those at JC were significantly finer. Sediments at GN were similar ;, ;, 6 , , 3 . 4
"* u'"S to previous years, and parameters describing the 1989 curve were not significantly different from = .
those describing the 2-unit curve, gg, 3 ,, Dr.'JL General Community Composition r IC*ila" / One hundred ninety-three taxa and 33,688 individuals were collected at the four subtidal { monitoring stations during 1989. Pclychaetes ga accounted for approximately half of the total i numbers of species identified at each station , (Table 3), while arthropod and molluse species Je ~ Ji e i > 3 7 s
~ ~ '
accounted for 21-26% The total number of species was greatest at EF and least at in 1989. =
@ im_e #A Polychaete individuals dominated at 3 stations in 3 ,, U2.'2%
1989 accounting for 69% 72%, and 57% of the j cD SA" ,(( total individuals at GN, IN and JC, respectively. p At EF, oligochaetes accounted for 58%, and polychaetes only 28% of the individuals collected. {" 3 Molluscs accounted for 11% of the individuals }n collected at IN and JC. No other groups # contributed more than 10% of the totals in 1989 , z, ;, e i , c . .
~ ~ '
Major taxonomic groups exhibited changes during 1989 relative to 2 unit and 3 unit years. ** The EF community in 1989 as in other 3-unit C",jL years, was numerically dominated by oligocheetes. g ,, QJ"g This contrasts with the 2-unit period when j c=-'=- -[ polychactes were the most abundant group. At IN, p "- , polychaetes dominated in 1989 representing a shift r from the arthropod dominated assemblage l observed in the 2-unit and in most 3-unit years. jn ,fj The contribution of molluscs this year was higher at IN and JC relative to the 2-unit period and all ,. F 4 , 3 unit years except 1988. Arthropod abundance Ja Ji 6 i e i a i ' ~ ~ " during 1989 at JC was similar to the 2-unit period, but lower than all 3 unit years. Ahundance of Fig. tt. Cumulative curves based on fractional weights of major groups at ON during 1989 was similar to sedimenis conected during the 2 unit (1980-85) period and each Ihat observed during 2. and 3. unit periods. 3-unit operational year (1986-89) ai Millstone subtidal stations. Benthic Infauna 163
i' 4 l TAllLE 3. Number of species (S), number of individuals (N) and the contribution to the totals (%) for each major taxon collected at ' Millstone subtidal statloas during 1989, whh means and toefficients of variability for 3. Unit operational years (19861989) and 2. Unit operational years (19901985). , L98,3 L996.,;g9,, - 1980415 l 3 1 H. 1 MEAN Q' MIIAN M' MEAN g~ MEAN Q- '
-i Efiluent 73 53.7 11,7 ' 4675' Polychaeta 2717 28.1 62 6.0 -
2130 67 2.7 2885 . 13.9 17.7 -
'{
'5642 Oligochacia - . . 53.1 . . 4712 17.9: - -
Mollusco . 28 20.6 : .370 3.8 30 3.3 ' $01 12.3 r 29 ' 4.8 497 ' 29.3 - ,
~
Arthmpuda .' 28 20.6 297 3.1 . 31 7A 445 16.2 39 4.5 723 21.9 Rhynchococla . .- 151 = 1.6 - . - 142 15.1' - - 138 23.2 -
'Others' 7 5.1 484 5.0 6 6.8 - 96 52.1 4' 20.4 11 . 48.7 Total . 136 9661 128 3.0 8146 9.7 139 2.2 8930- 12.3 9.iSBILHssli
- Polychaeta 54 49.5 7062 69.2 65 - 7.1 70R8 9,5 - 67 4A 6683- 12.9 Oligochaeta . . 2422 23.7 . . 2253 6.8 - . . 1932 12.6
. Mollusca 25 22.9 183 1.8 29 4.2 244 13.1 ~ '20 9.9 260' 20.7 J 3 26 23.9 '492- 4.8 36 27A 4.6 ' 624 - 5.8 , '
Arthn3xxla 12.8 1283' 35 - Rhynchocoela . . 42 OA - . 58 11A- . .
. 62 -20A
'Others' 4 3.7 5 0.1 4 20A 11 43.0 3 26.4 8 43.2 Total - 109 10206 132 8.3 10937 . 7.9 125 4.1 9569 10.1 .
l, ' intake
,t Polychaeta 52 55.9 2909 72.1 51 2.7 2411 12.2 '43 33 1110 9.3 Oligochaeta . . 260 6A . . i244 20.8 . . 253 16.2' Mollusca 20 21.5 447 11.8 20 5A 621 11.7 - 18 L 10.8 -199- 27.0 Arthropoda 21 22.6 370 9.2 - 25 6A - 2873 59.6 - 25 8.2 829 47A Rhynchocoela - . -
21 . 0.5 - - 28 - 29.3 . . 15 - 26A
'Others' O O O . 0.0 2 63A B 35.9 -1 68.3 1 74.2 Total 93 4037 97 2.7 6178 29.1 - 86 5.5 -- 2405. 14.6 Jonian Cove Polychaeta 59 .49.2 5579 57.0 62 1.7 6555 20.0 64 4.7 6543 -23.2 Oligochaeta . . 2.448 '25.0 . . 2517 8.7 . .
4124. 24.2 - Mollusca 31 25.8 1055 10.8 30 4.0 786- '12.3 _ 24 12.8 446 ' 24.6 Arthro [xxla 26 21.7 565 5.8 29 8A 1349 - 41.7 27 6.2 641 55A 4 Rhynchocoeta . . 99 1.0 . -
- 83 10.6' . . 79- '12.3
'Others' 4 3.3 38 04 5' 11.1 17 - 40.5. - 3; 33.1 4 28.1 Total 120 9784 124 2.9 11306 13.6 ~ 116 5.8 12113 13.3
- *C.V - (Standard Error /Mean) x 100 l
164 Monitoring Studies,1989 ' i
J
- 1 P
a Community Abtmdance - sfATOP4 EFFLUENT $v011DAL r Ranges of average quarterly abundance (per a' w j core) at cach subtidal station during 1989 were [,,, . 140-290,210-287,71 142 and 179-404 at EF, ON, IN and JC, respectively (Fig.12); - Highest E g '= A g g ' @ Q p ,v>q. g abundance occurred in September at EF and JC s i and in June at ON and IN; lowest densitics } ,, occurred in March at EF ON and JC and September at IN. In general, quarterly values during 1989 were within the range of those ',,,,,,,,cy,,y,,,,,,,,,,,,c,,,g,, obtained in all past years, and regression analyses ' indicated that no significamt trends in abundance = ' were present at any station. Explanatory variables ,,,_,,,,y,,,, t in mL!tiple regression analyses removed 24 47% of a' m - ' the variation in subtidal community abundance. . l,,, , i The annual adjusted means during 1989 at EF, E- lf%%@>y%%/ ' *
- 3 ON, and JC were not significantly different from ' **
[ '- . prior years. At IN, the 1989 mean was significantly -8' ir higher than those for 1983 through 1986. Infaunal l ,, abundance at EF, ON, and JC during the 3. unit period was not significantly different from that of- '
- the 2 unit period, whereas at IN abundance was ',,,,.,,,,,,,,,,,,,,,,,7,,,,.,,,,,,,, ,,,,g,,
significantly higher during the 3-unit period. Number of Species ,,A,,,,,,,,,,,. a 8
- D J7 Ranges of average number of species (per core) ! ,
during 1989 were 2129 at EF,19 28 at GN,17 23 E' . at IN and 23-35 at JC (Fig.13). In general, values at all stations during 1989 were within the range of 8
, y
- J,f . '
l ,, ** those observed in prior years and no significant ,', long-term trends were evident at any station. Multiple regression analyses removed 18% (EF) . ' y ,,,u . u,cy#u uso um us.,um u m uso u#u to 38% (JC) of the temporal variation in species. '
- number observed over the sampling period.
Covariance analyses revealed no significant s,Ato. ma cu sustm
,, differences between the average number of species - "'-**'
collected in 1989 and other years at JC. Mean E, number of species in 1989 was significantly lower E N M , [J. than 19841986 at ON, significantly higher than I '* 1980-1984 at IN, and significantly lower than 1984- 5 1985 at EF. The IN station was the only area l ,, where there was significant difference (higher) in the number of species between the 3 unit and 2-unit periods. ' y #,, um u,,, u#u u#u u,,, u,,, ne , us., u, u. . Fig.12.' Quarterly mean abundance and multiple regression - l ( predictions ror Millstone subtidat communities from September k i ' 1979 June 1989L Benthic Infauna 165 i y
t 6 l r
- Community. Dominance swo , smuc n suam ,
- a ' + o is
- Oligochactes and: the polychacte, Aricidea l- ,
catherinae, were the numerically most abundant - E* *
, subtidal' taxa collected in 1989. 011gochactes B , ,
_,' ranked first at EF and JC, (58% and 25%, of the _ ; E* ,, , ,, totals, respectively), second at ON (24%) and sixth :
} a at IN (6%);(Table 4). Aricidea catherinae was first <
at ON (31%) and second at JC (18%) and IN (17%). Also dominant during 1989 _wcre u+,, um u+e, um um um um um un, u+= u,,, Protodorvillea gaspeensis (7%) and' Haliplanella , luciae ($%) at EF; Lumbrineris tenuis (10'ib),'- Polycirrus eximius (6%) and Nucula proxima (6%) > uo,. c ns.nen so.% at JC,'and Tharyx spp. (12%) at ON. - At IN, [ n'-vu. Polydora quadrilobata ranked first (17%), . ' A. : 5- catherinne second (17%), Capitella spp.'(9%) and
-E* , , ,
Nucula prarima (7%) third and fourth during 1989.
. ". ,' Relative to the 2 unit period and other 3. unit - )
- l. " .
, y years, some shifts in dominance structure were ,
, . evident during ' 1989. At EF, the increasing'
.. dominance of oligochactes continued in 1989, a "ve,.um um um viu um usuum unrum u. trend which has occurred since 3. unit operation began, f!'his group accounted for over 50% of the
") ~
, individuals in 1989 and'over the entire 3. unit swm wisuem
- period,' but only 33% in the 2. unit periodi -In
* ****" , . additlon, Polycirms eximius and Aricidea catherinae . +
E ',' . were less _ dominant in 1989 :(Table 4),: again r E" ' continuing a trend evidcnt since the beginning of
.k,.
E , . 3 unit operation. - At JC,- infaunal community
/
l composition in 1989 was simllar to that observed ! } , .
/ over the entire 3. unit periodc. Relative to. the 2 l ,
unit period, we have observed rehced dominance 1 of oligochactes and Aricidea catherinae, ~ but
'u m us.o u m u m u ,'u u n. u m u m u n , u m u m _
generally higher dominance of Lumbrineris tenuis, Nucula proxima, Microphthalmus aberrans, Leptecheirus pinguls, ' At 1N,' Nucula pratima and swo. ow. cu su,% Leptocheirus pinguis dominated during the 3-unit period while oligochactes, Aricidea catherinae, b . Tellina agilis and Ampetisca verrilli dominated E*
- during the 2. unit period. The ON community.
8 ', ' exhibited i few temporal' shifts: with Ariciden E" '. ., , catherinae, oligochaetes, - and Tharyr -spp. k '
,, dominating during the 2. unit and 3. unit periods.
Dominant Taxa -
'se,,umu,umumumumumumumum Multiple regression-techniques and covariance '
Fig.13. Quanerty mcan species number and multiple regression analyses were used to identify long-term trends, predictions tor Millstone sutilidal communities trom September 1979 dune 1989. -comEare species abundance in 1989 with other.
, years, and to compare abundances between the 2 I
a 166 Monitoring Studies,1989 l
' TABLE 4.- Relative abundance (%) and coeflicient of variability (CV) for cach of the ten most abundant taxa collected at the Millstone i subtidal stations during 3-Unit operational years (19861988) and pre operational years (1980-1985).
1989 .1980-85 1986-89 s-Emuent . .G) (t) E' .. (,1) - E-Oligochaeta . 58.4 .32.9 4.4 56.7 ~ 23 -- l>otodonillea gaspceruk 1.2 ' 4.6 133 6.9 ' ' 4.4 11aliplanella luciae. J 4.? : 13 70.7 3.0 ' 26.9 ' Caulleriella spp;. 23 1.8 . 24.1' 2.1 - .21.9 Polpirrus crimius 1.9 10.8 10.2 1.8 ; 44.0 Rhynchococla - 1.6 2.4 12.2 2.7 ? 9.2 - Syllides scrwulata 1.6 - 1.2 .' 28.6 - 1.4 $1.0 - 7 harp spp. 1.5 2.6 28.1 2.9 i - 26.9 --
- Capitella spp. 1.4 ' 2.0 .103 1.7 30.5 Parapiormfla longicirrota - 1.4 1.6 . 18.8 ~ 1.8 27.5 :
Neanthes ncuminata - 1.3 - 1.2 78.5 - 1.4 - _ 563 Te/hna agils 1.2 - 2.9 17.9 2.9 ' ;17.3 Lumbrincris tenuh - 0.9 1.8 31 3 '. l .6 ' 20.3 Alicrophthahnus aberrans 0.8 1.5
- 23.7 _ ' 1.8 : 93 Archiannelida 0.7 1.6 - 25.2 - 2.0 30.5 -
Paprus acadianus 0,7 ' l.6 :26.2 1.7 ' 14.0 '
. blytilus edulk 0.5 13 47.9 -- 1.8 46.2 - - IWydora caudieryl 0.5 2.4 - 27.3 . 13 16.2 Eumida sanpinca 0.4 2.2 ' 20.9 ^ l.2 17.4 Gammarus lawrencianus 03 1.4 463 - ~ 1.1 69.2 Aricidea catherinae 0.2 4.1 - 20,6 ' ' l.2 - 30.6 '
Leptocheirus pinph 0.2 1.6 41.9 'I .4 38.3 l>ionmpio steerutrupi 0.2 1.5 31.4 13' 38.7 Spiophanes bomby 0.2 1.4 25 3 ' 1.5 L - 56.5; Jonbn Cove Oligochacta 25.0 40.8 3.9 . 23.6 6.1
' Aricidea catherinae i83 14.8 - 6.1 9.8 12.7' Lumbrincru tenuh - 9,7 4.7 ' 13.1 - ' 6.4 '- 11.8 ~
Polycirrus crimius 5.7 4.3 . 3.5 -- 14.2 : 20.6 - i Nucula prarima 5.6 13 13.l" 2.7 . 35.4' l Slicrophthalmus aberrans 4.7 1.5 _ 22.6 . 3.9 ' - 18.9 Leptocheirus pinpis 4.2 1.5 34.5- 6.4 . - 3l.9 ^ ofcdiomastus ambheta 4.0 7.2 L 263 - .163 16.1 -i 7haryr app. 2.6 3.1 l133' ' 3.8 - ! 5.0 - Capitella spp. 1.7 2.2 17.9 - 2.0 22.2 Pohdora quadrilobata 1.1 ' l.1 41.8 1.8 . 45.7 Pn'onwpio sacenstrupi 1.5 ' 1.4 24.8 , 2.6 . ' 4.6 ; - Afytilus edulis 1.1 1.0 ' 100.0- ' 1.3 ' 83.5 Nucula delphinodonta - 1.1 1.0 " 0.0 1n . 39.0: Tellina agilu 0.9 2.2 23.6 2.2 64 Eropne hebes 0.8 ' 29.9 1.5 - 1.6 2031 ofitrella lunata 0.7 1,1 31.8 1.7 ' 39.5 Photoeminuta - 0.6 1.5 213 . l.9 31.2 ':
'CN =(Standard Error /Mean) x (100)
Benthic Infauna' :167
TABLE 4. Continued , t 1989 1980 45 1986-89 E G $ E E lala!m Polydora quadrilobata 16.7 2.0 38.8 3.0 58.7 - Aricidra catharinac 14.6 6.7 18.2 4.2 37.9 Cqrdella spp 8.9 3.9 24.9 4.2 39.4 Nucula prariina : 73 2.6 26.5 6.4 21.9 Erogone heber 6.6 3.9 23.1 2.7 ' 46.6 Oligochacia 6.4 11.1 9.4 53 20.9 i Micreyshthalmus aberras 5.2 1.4 31.0 2.6 40.0 Lepwchenna pinpas 3.7 3.8 42.7 63 31.1 Pyyupio ricpru 3.0 2.1 - 37.0 2.1 87.1 Tritina agith 3.0 43 15.9 3.6 ' 10.8 Oweda fluiformh 2.4 13 29,8 3.9 24.7 7 harp app. 2.0 1.2 33.8 2.9 13.8 lyprodonillea puperruis 1.6 1.9 23.4 1.7 48.4
/>nciola irrorata 1.6 1.5 33.7 3.1 22.9 Ampelkca verrilli 0.9 4.7 21.5 3.2 323 Spiophancs homby 0.9 2.8 24.9 1.7 - 22.5 Giants Neck Aricidea catherinae 31.1 . 19.6 5.0 17.2 83 Oligochacia 23.7 20.8 3.9 14.6 3.4 Tharp spp. 11.6 13.8 3.9 - 4.8 6,9 Prowdorvillea pupcensu 43 3.8 ' $.5 2.4 4.9 Polgirrus etirnius - 3.7 3.4 12.6 3.8 28.4 Lumbrineth tenub 3.1 3.1 14.1 2.4 5.0 Microphthahnus aberraru 2.6 1.4 19.8 2.0 35.9
> Polydora quadrilobata 2.6 1.4 '50.0 33 37.3 Eropme dhpar 2.2 2.7 19.6 2.0 - 6,6 Phatraphalus holbolli 1.6 2.7 13.0 1.8 17 3 . Polydora caulicryi 13 2.2 32.0 1.9 15.1 Capisella spp. 1.1 1.8 19.4 1.9 15.2 Mediomastus ambbeta 0.6 4.8 27.5 8.2 28.0 ' lyioruupio st<cruarupi 0.6 - 2.0 16.1 1.7 7.7 unit and 3 unit periods. Taxa included in this . and spatial fluctuations in abundance as the section were among the most consistently amount of detritus within the sediments varies. dominant organisms during either 2 or 3-unit Oligochactes accounted for the highest percentage operational peritxis. of the total individuals collected at all subtidal stations during the 2-unit period (See Table 4). Oligochaetes During 1989, oligochactes were the most These small annelids have been the most abundant organisms at EF and JC and ranked ubiquitously abundant subtidal taxon during our second at GN and sixth at IN. Ranges of quarterly study. Feeding on the fine deposits incorporated . densities per core were 90156 at EF,36-70 at GN, - within the sediment, oligochaete taxa 2-10 at IN and 43-87 at JC (Fig.14a.d). Values at - characteristically exhibit both rapid (Olcre 1975) EF in 1989 were among the highest ever recorded. and marked (Price and Hylleberg 1982) temporal in contrast, those at JC were among the lowest. Regression analyses revealed a significant 168 Monitoring Studies,1989
=
increasing trend at EF and a decreasing trend JC. swio,,in cise m At IN and GN, values for 1989 were within the gigs, range of previous years and no long term trends [,,,, were evident. E i= , fW,W ggb After applying multiple regression techniques i and adjusting for natural variation, oligochacte l" @'*
- abundances at GN and IN during 1989 were not significantly different from any previous year. At EF, the 1989 mean was significantly higher than un w.o uni um um w.. um um w., um w..
1980-82,1984 and 1986; at JC the 1989 annual mean was significantly lower than that of 1980,-
==
1982 and 1983. Overall, oligochacte abundance at s,.ro,. cons,*n sue'm b-
. . . so higher than that during the 2-unit period, while
['" that at JC_was significantly lower. No significant g differences between the 3- and 2. unit periods were g= cvident at GN and IN. g s VMMh* Mediomastus ambiseta
' Afediomastus ambiseta is a relatively small I ue,. um ne u u,u w.. mm. um u , um us,, polychaete frequently abundant in areas of
" environmental stress caused by disturbance or organic enrichment, but it also commonly inhabits sww .a.a sma e, silly sediments along the entire U.S. cast coast oO 'd,'.. (Boesch and Rosenburg 1982). Considered an E.= ' opportunist", this - species has shown large r
population pulses associated with oil ' spills
$* (Grassic and Grassle 1974; Sanders et al.1980) i j
and organic enrichment events (Boesch and
.. Rosenburg 1982). Based on average percent abundance during the 2 unit operational period, Af. ,
ambiseta ranked third JC, fourth at GN and sixth- !
'wv. n e.o me. um wu we.. neu so'.. m., usu w., at EF and IN.
During 1989, the ranges of densities _ of i swic mo.,.cm susnos e, Afediomastus ambiseta were 0-1/ core at EF, 2- i oO,' ?., 3/ core at GN,12/ core at IN and 2 27/ core at JC 5.- (Fig.14c-h). At all stations except JC, quarterly. r .... .l density values during 1989 were lower than in any I* 8
. W /" C V N'4N9 L A / % 'A' "..* year since 1983. Regression analyses of quarterly
'. ',. data collected since 1980 revealed a significant decreasing trend at EF, an increasing trend at IN and no trends at' GN or_ JC. Analyses of covariance showed that the 1989 mean abundance
'un, um me. ven wu w.. usu um w., um w was significantly lower than the means from 1984-1988 at GN, EF and JC (except 1985 at JC).' At n s. 14. Quanerly mean abundance and multipte regression IN, the 1989 mean was lower than 1986 and 1987.
predictions for selected dominant organisms comprising i Mdistone subsidat communities. 1 Benthic Infauna 169 l I
== At all stations, however, there was no significant difference in the abundance of Af. ambiseto
....e
'- ' between the 3 unit and 2. unit periods.
g Aricidea catherinac I*
... Aricidea catherinac is a frequent component of 5 ,. **
listoral (Whittatch 1977; Kinner and Maurer 1978)
'"' and offshore (Maurer and leathem 1980) macrofaunal communities. In the Millstone area,
'u.".'um$$.1 um um um um whu A. catherinac was among the numerically dominant !
species at all subtidal stations during the 2 unit operational period. Although most abundant at vam caesweisumm t. ON and JC, where it comprised 19.6% and 14.8% - L '4',,',' of the animals identified during 1980-85 (Table 4),
- 5. this species was also a component of the EF E (4.1%) and IN (6.7%) communities during 1980-I" ,. ., 85.
I
., In 1989, Aricidea catherinae ranked first at ON
. and second at JC and IN (Table 4), at EF, this
.. . . . ,. .. species accounted for less than 1% of the
'u m u m u m u m u m u m u m u m nec u, us m individuals sampled. Ranges of average quarterly density (per core) were 12 at EF,54-117 at ON,
. 8-21 at IN and 25 72 at JC (Fig.1411). Regression vam; .v.c iumm g. analyses of quarterly abundance revealed ;no
% ' * **,,,. significant trends at ON, IN or JC. while' at EF, .
E. there was a significant declining trend from 1980 E to 1989,' The 1989 annual mean at ON and JC was l *' - -' not significantly different from any previous annual y . ... mean At EF, the 1989 mean was significantly , 3. .
. lower than all 2 unit years (19o0-85), in contrast.
. the 1989 mean at IN was significantly higher than that observed in all previous years.
um um um um um um um um um um um Polycimis eximius ma m m o= c m som m h. Polycirrus eximius is a deposit feeding polychaete common to shallow-water marine and brackish E= .. waters along the east coast of North America E ' (Oosner 1971). This species was the second most I" ' abundant macrofaunal organism at EF during the -
) .. ,' 2 unit period, and on average, accounted for over 5= .
, 10% of the total individuals collected from 1980-
*- 1985. At JC, P. eximius ranked fifth and at GN
., sixth during the 2-unit period. At IN, this species um um um men um u . um um u.o um um has never ranked among the top ten numerically Fig.14, continued.
During 1989, Polyrirrus eximius ranked fifth at I EF, ON and JC (Table 4); quarterly numbers per 170 Monitoring Studies,1989 l
4 k QM
.[
$1 ATE)f. (FfLtKNT $USftpAL -
( $fATIOK' EPPLuf NT MTO4L n' o em - g, - -
- e s . e.s.7 de.e.d. eewsw.e. *em Fedyrerews estme.m s .s. .
,,. 1 4 '
s
- g. - .
'.a...m.
.. . ... .s , ,. _ _ _ _ .
uP79 Streo utet SEP63 SEP43 $(P94 $(Pts StP98 54P97 uP98 uret SEP79 uP90 urel SEPT 3 ups) SEPe4 SEPTS StP94 SEP97 uPee 5(Pet ; s
, ,e , --
- STA110N GMf3 NCCat SUShDAL j, STAh0N GMT$ DsCCs SUBT10.L . - n.
0 28 0.12 .-
.es 3,84 w.,s.0 22.g.,, '. We p.4y.emas setmiu. '
s e a
- 1. i. .. ... . . .
.. .. t.
uPm um uni uPea uPe uPe. upas um une stree s: Pee uPro uno uni uPea um_:(m uns sten um st~es stPac saa cae. sTAton virus suoriodt k, $TATifM ARCAN COW $USW ' O. y as e,i . o ie.g,, 4 . - g** a.s r a,. o.i.e m .eu , 8 8 i E E
.. -i g ,. . -
r= .- g ., _ 5 . .
. y ,.
q w ..
. . . 1 y
S(PF9 5(PSO Stret StreJ S(P63 uPs. uP63 $tP86 $4P97 SEPet SEP89 uPit SEP30 SEPSI SEP82 uPSj $(Pg4 MP451[P66 uDe7 $fPte SEPSG .
'" ^
Fig.14 continued.
.^' ~U$"
core ranged from 2 '8, 512,' and' 2'25 at'_'these l t g"" stations, respectively (Fig 14m 0)/ In general,1989?
- j values' at' all stations were higher than' thoses g
- obtained during the last three years but within the i, a .
, range of those obtained during the 2 unit period.
j" , . , Based on regression analyses, the EF station was-L '- the only area where a_. trend- (decline)' was statistically significant in the period of 1980.to - L i um uno uni um um um uns um um um um 1989. Analyses of covariance revealed that the 7 1989 adjusted mean at EF was not significantly 1 Fig.14, continued. different from any prior year, while at JC the 1989' mean was significantly different from only 1984.'
- At GN, the 1989 mean was significantly different; from all years except 1980,1981 and'1985. '
Benthic Infauna 171 L I i, i
t However, significant differences between the 2-unit stations, abundances over the 3 unit period were and 3 unit periods occurred only at EF, significantly higher than those obtained during the 2 unit operational period. Proiodorvillea gaspeensis Lumbn,nen,s tenm,s. The polychaete, hotodorvilka gaspeensis, is a small facultative carnivore (Fauchald and Jumars Lumbrineris tenuis is a burrowing deposit feeding 1979) common in near shore sublittoral polychaete that consumes a variety of food itenu environments from the Gulf of St. Lawrence to including sediments, algae, ec1 grass detritus or LIS (Pettibone 1%3). This species ranked third other infauna species (Pettibone 1%3), it is and fifth at EF and ON during the 1980-85 period, common at subtidal depths up to 60 m from Maine respectively (Table 4). During the 3-unit period, to the Gulf of Mexico, and is foand in muds, sands P. gaspcensis ranked second at EF and fourth at and eclgrass beds (Pettibone 1963) Lumbrineris ON. tenuis ranked fourth at JC and seventh at ON
, during- 1980-85, respectively (Table 4). . This 1 During 1989, ranges of quarterly abundance (per species was ranked similarly over the 3 unit period, core) were 8-21 at EF and 519 at GN (Fig.14p-q) accounting for 6.4% at JC and 2.4% at ON, i with values at both stations near the upper end of the ten year range, Regression analyses identified Ranges of quarterly numbers per core during significant increasing trends at both stations from. 1989 were 6 8 at JC and 16-45 at ON (Fig.14r s).
1980 1989. The 1989 annual mean at EF was In general, quarterly means in 1989 were at the higher than 1980 and 19821987 and at ON,1989 higher end of the range observed since 1980 and at , was higher than 1981,1982 and 1984, At both both stations a significant increasing trend was evident. The 1989 annual mean at JC was
==
STAT IFFLUENT su9h $ 11 NT$ MCM s00% g, g- , .. - g-i e
- g. g. -
, e E
/
uris um uni um uros une uros area uro u se sc,s. were ueen urei urs2 uros urs. uras urne urer uros uros '
- m. -o sanoi. r,was aca sveh q. sanonerwa co4 svem s.
g- f :?.L .
- f : ." . -
e F l- 6" E - E
,g % 1*
'uom um u*ei um u*ss use. uns um uns um um upm u*eo uros um um ure4 uros scene ures strasi stpe.
Fig.14, continued. Fig.14, continued. 172 Monitoring Studies,1989 1 I
l significantly higher than values obtained in 1980, == 1982,1983 and 1986. - At GN, the 1989 annual mean was significantly higher than 1980 and 1981, EN.P'"
- At both stations, there was a significant increase in abundances of L. rensis during the 3-unit period,
[~ p , Capitella spp. I~ s I ,. Capitella spp. are small, tube dwelling -
, i polychaetes frequently cited as indicators of A pollution or stressed environments (Reish 1%7; ' -
,,,, ,,,,, ,,,, ,,, ,,, ,,,, ,,,, ,,,,y,,,, ,,, ,,,
Wass- 1%7). They are commonly found in oxygen. depleted basins,- sewage outfalls, sludge " " ' dumps and sediments contaminated by oil (Sanders p.m,, s 1% ,, et al.1980). - However, these organisms are also ;Ol,g6
' found in unpolluted shallow water areas (Hyland l, et al.1985). Capitella spp., although present at all 9 stations during this study, usually account for less
[" than 5% of the total individuals. This taxon
- ranked seventh at JC and IN and eleventh at GN $ ,, _
during the 2 unit operational period. During 1989, . *.* Capitella spp. accounted for 8.9% of the individuals at IN and 2% and 1% of the totals at ',,,,y,,,*,*,,,, , ,M*,*,,,-g,,w ,, ,,,,,,,, ,,, JC and GN, respectively. Ranges of quarterly abundance per core in 1989 ,,1. ccm ,. ,, were 2 8 at ON,317 at IN and 2 7 at JC (Fig.14t- ;,'g,,yb v). Except at IN, the 1989 means were typical of l,,. . those observed in past years and no significant E trends have occurred at any sampling station. The 1989 annual mean at GN was not significantly- [* E i
,different from any previous year, while the 1989 l ,, ,
mean at JC was significantly higher than 1982 and *
^.
1986. At IN, values in 1989 exceeded most ' previous abundances and the resultant annual- '
,,,,y,,,, ,,; ,,, ,,, ,g, ,,,, ,,,, ,,,, ,,, ,,,
mean was significantly higher than all years except ; 1988. Because of high values in 1988 and 1989, ng.14, conunued. j the abundance of Capitella spp. showed a j significant increase over the 3-unit period relative ranke(1 organisms at any station during the 2 unit ; to the 2 unit period. period, but ranked among the top ten at IN and JC during the 3 unit period (Table 4). { N4ta4/a proxima During 1989, average quarterly abundance (per Nuculaproxima is a deposit feeding mollusc that core) ranged from 2-13 at IN and 2-32 at JC (Fig. ! lives in fine or silly sands (Hampson 1971; 14w x), with values at both stations exhibiting Levinton 1973). Frequently growing to only 7 mm, wide fluctuations during the year. Abundances at this long-lived (6-8 years; Carey 1962) species lives IN were within the range of previous years while slightly below the sediment surface (Stanley 1970) those at JC were near or exceeded previous years' I
-and uses its palp proboscides to feed highs. At - both stations, . abundance has - !
non. selectively on subsurface sediment (Levinton . significantly increased during the monitoring 1973). Nucula proxima was not among the top period. On an annual basis, the 1989 adjusted' mean was significantly higher than 1980-1984 at IN. ! e Benthic Infauna 173 i
s
$7 Alto,e setAF( $USTM W,
- ws -. I - '
E-s I ,, ,
- I ,
$1A110N:(FILUENT $uBfM i
)* +
lR*AT '
;g: L -
I
, in..c
- m. HPee Mrge.MPG _ _'.' '
'T i ,' ~
i MPP 2 MPS3 MP.4 M795 MFe6 M*97 KPee MPee sett(s queu (in) StateDet JORDAN CM SuSIM g, , g= IM#- / e - r ,, g- ,, a ,
' - Im;'AT l -
ly' . l{E5N ' M , - - m ,,. u m n i u m u m u m u m ur.. u ,.> u , u m
', i mea ti.3 3 ,
~
Fig.14, continued. a o, and higher than 19801986 at JC. There was, j however, no significant differer.cc in abundance g
/ 1 between the 3, unit and 2-unit operational periods -,
at either station. 5fAft0N. 94 TAME SLGftDE I Cumulative Abundance Curves :==g;-
-!=:
L Cumulative abundance curves of the ten most
- l abundant organisms-were plotted for the 2 unit . i i 2
"'""'*)'
(1980-85) and for each 3-unit operational year " (1986-1989) (Fig.15). T-tests were used to identify , differences among parameters derived after fitting # , cumulative abundance data to the Gompertz j function (See Materials and Methods). g , t ! Community structure at all stations except IN I" during 1989 was significantly different from that - ;,o.,, cu su rm - observed during the 2 unit operational period. {' ir.iio
; mg;* ;'
r The dominance curve for EF in 1989 was relatively IE:L flat compared to that based on 2, unit data due to
- the dominance of oligochaetes. The dominance . i i .2
"""*')
- I, structure at IN during: 1989 was significantly i different from 1986 and 1987 but not from 1980- Fig.15. Cumulative species abundance curves based on the top
- 85. In former years, one taxon,(i.e., Mediomastus ten numerically abundant organisms collected during 2. unit ambiscia in 1986 and Leptocheiruspinguis in 1987), (198045) and 3-unit (1986-89) studies at Miltstone subtidal Stat 40ns, t
174 Monitoring Studies,1989
i accounted for over 40% of the total organisms; in i 1989 a more even distribution of indMduals per -[ i taxon was evident, - Similarly at JC, reduced abundance of Mediomastus ambiseta and , ] Leptocheiruspinguis in 1989 resulted in more even 5 '* t"* l distribution and a more sigmold shaped cumulative a Z"("j)j--~7 curve. The GN curve for 1989 was typical of those obtained in past years with the community cxhibiting a more even distribution of individuals , l among species than 0ther stations. .. "'"--~~~~--- --'
'" '~ '" '" '~ ' " ' ' " " ' ' ~ ' ~
Species Diversity f Annual mean species diversity (H') and evenness anxr n,ux (J) based on quarterly subtidal collections _ from e sn e x-----) September 1988 June 1989 are presented for each station in Figure 16. Diversity averaged 4.6 at EF, - 3.3 at GN,3.4 at IN and 4.0 at JC during 1989. 3-l k Evenness values ranged from 0.6 (GN) to 0.7 (EF). ', Average diversity and evenness indices during 1989 vMghest at EF and lowest at GN. ..
. _ - . . ~ . . , _ . _ . _ . . , _ . . . . . _ . .. ,
For all subtidal communities, diversity measures ,. ,. .. m .. . . . . . . . _ . during 1989 were within the range of annual means observed since 1980, although values at JC and IN .. a were at the high end of this range. These high unw ar values reflected the sharp declines in the msw en.---a polychacte, Mediomastus ambiseta, and the *"*"~~" am phipod, Leptocheiruspingun, species whose high abundance caused lower evenness and subsequently ' 2- h "
, Jower H' values in past years, The temporal ,
variations evident in diversity parameters show no major structural shifts in subtidal communities. .. _......,......,..._p..-...., Cluster Analysis . ,. .. .. .. .- . . - , - . Classification of organism abundances averaged + during the 2-unit period and in each of the 3-unit - swa == cm years produced a dendrogram of two station groups Z",f"]j,;,34 that linked at low similarity (53%) (Fig.17). .
- i Group i represented stations where -infaunal N [
l- abundances were high and the numerical dominants were oligochaetes, Aricidea catherinae, ,
- Polycimas crimius and '_ Mediomastus ambiseta. >
I, With r, Group I, statWs separated into three i- ' groups, with 2 unit cohulons at EF, GN and JC, ~
~"~"~'~-*~~"~~~l~~' !
separating from 3 unit operational years. Subgroup A included 2 unit collections (l.c., EF-i= im im >= i= i= i- i- i= i=
]
8085, GN 8085 and JC-8085) and the 1986 JC ng.16. Annual mean species dwenity (t!') and evenness (J) i collection, all of which were dominated by Tharyx 1 sE- for Millstone subtidal communities sampled from spp., Polycirrus eximius, Aricidea catherinae, P'**b''*)""**' Benthic Infauna - 175 i
1 0-
' 10 - ,
20 - h 30 - i f 40 - ; O SD -
!ii
_ d 60 - , ; h ~70 - 80 - A 90 I 1 I I ,b -
?
4 t t Q, C4 Q Op 4 4 4 4 4 Q'.
~$ q db ~&e '&p % I'e> 'eet~ds t~&>t~&e ~&p ~&c~&> ~6e?&ql$ ~$ ~& $~&
*> ~&e Go Fig.17. Simitarity dendrogram based on mean species abundance during the 2 unit operational period (1980-1985) and in cach 3 unit operational year (t986-1989) for Millstone subtidal communitics.
Leptocheuus pmguis and Mediomastus ambiseta. Discussion Subgroups B and C contained the 3-unit
. operational years at JC and GN, Although these During 1989,160 samples were collected at four stations shared some taxa, dominance of these taxa subtidal stations as part of the long-term sampling _
differed between stations. At GN, Tharyr spp., A. program to assess whether any changes in local catherinac and Protodorvillea gaspeensis were macrofaunal communities have resulted from 3-dominant, while at JC, Af. ambiseta, Lumbrineris unit operation'at Millstone Nuclear Power Station. tenuis, and especially L. pinguis were numerically Results of our studies indicate that both natural-dominant. The EF collections within Subgroup C and power plant related changes hr.ve occurred in separated from of other stations because of the low local subtidal communities. These changes will be ' abundance of Af. ambiseta and L. pinguis observed addr'essed below.- in 1986 and 1987, relative to other stations, and to the high abundances of oligochaetes (1988 and Naturally = Induced Changes- , 1989). Macrofaunal communities within the Millstone The second major group (Group II) contained Bight area ' arc dominatedi by- annelids, with the IN collections, which were lower in abundance - arthropods and molluscs being either temporally or-and often dominated by Ampelisca spp. and spatially' important. Organisms comprising these Leptocheiruspinguis. Separation of 1986 and 1987 communities exhibit seasonal and year to year from the 2 unit years (IN.8085) was due to the . fluctuations in abundance on both a site-specific large increase in the abundance of Afediomastu3 and region-wide basis (i.e. . Orcater - Millstone ambiseta and either Ampelisca spp. (1986) or Bight). These fluctuations are frequently . Leptocheirus pinguis (1987). The separation of attributed to variations in mortality, recruitment, 1988 and 1989 from earlier years was due to the competition, predation and to changes in the local reduced abundance of-amphipods and increased physical and chemical environment (Watling 1975; y abundance of the mollusc,Nuculaprarima and the Flint and Younk 1983; Nichols 1985). During our l polychaeter, Polydora quadrilobata, Ariciden study, large temporal fluctuations were most catherinae and Capitella spp. evidenced by the polychaetc, Afediomastus - 1 ambiseta, and the amphipods, Leptocheirus pinguis and Ampelisca spp. During 1989, the abundance l'16 Monitoring Studies,1989 l l l l
I of Af. ambiscia at most stations was significantly Power Plant Related Changes lower than that observed from 1984-1987. IAw values in 1988 and the near disappearance of Af. Power plant related changes in local infaunal ambiscia in 1989 caused shifts in many indices used community abundance and composition have been to characterize community structure and identified since 1984 when construction of the Unit composition. 3 intake and dredging activities affected communities at the IN station (NUSCO 1985). Afediomastus ambiscia is considered to be an Additional changes occurred after Unit 3 start-up
" opportunist" and dominates recently or (NUSCO 1986) and subsequently during 3 unit continuously disturbed areas (Grassic and Grassle operations (NUSCO 1987).
1974; McCall 1977; Sanders et al.1980). This species is also common however, in undisturbed Construction impacts identified during our study subtidal areas throughout New England (Sanders were principally. restricted to the IN station, 1 1958), and is considered a member of the located offshore of the Millstone cooling water
' equilibrium community" in LIS (Pratt 1973; intakes. Power plant related impacts on the Rhoads et al.1978). During our studies, Af. -infauna of this area, first observed in 1984, were ambiscta was a frequent member of all subtidal attributed to siltation created during Unit 3 intake communities, exhibiting large and relatively long- construction (NUSCO 1985). Prior to '
term (multi. years) increases in abundance followed construction, this station was characterized as a by rapid declines leading towards local extinction. highly dynamic environment influenced by strong - Similarly, Sanders et al. (1980) reported that AI. tidal currents; sediment contained less than 10% , ambiscia can monopolize the bottom fauna over silt-clay and the infaunal community was periods of years, accounting for 20-95% of the dominated by suspension' feeding amphipods total fauna. Although the temporal shifts observed Ampelisca spp. and the polychacte, Sabellaria during this study could not be explained by the vulgaris (NUSCO 1981). Following the year to-year changes 3r .limatic and sedimentary disturbance, sediment silt / clay increased to over - factors used in our studies, the occurrence of these 10% and opportunistic species such as Capitella , changes both at our potentially impacted and non- spp., Polyrlora ligni, and Owenia fusiformis became impacted stations suggests that the cause is'of abundant; as the sediments stabilized, these species " natural origin and not related to power plant were replaced by tube-dwelling amphipods, pperations at Millstone. Ampelisca spp, and I,cptocheirus pinguis (NUSCO Like Aiediomastus, the amphipods, Leptochcirus pinguis and Ampelisca spp. have exhibited arca- During 1989, grain size and silt / clay content at wide increases in abundance which have influenced IN closely resembled 1988 values, and both were observed patterns of community structure, relatively similar to those observed before the composition and abundance (Blernbaum 1979; construction period (NUSCO 1985). Community Sanders et al.1980; Jordan and Sutton 1985), in abundance and number of species, although higher, 1989, as in 1988, abundances of these species were closer to pre 1984 values. The infaunal remained low following the large increase in 1987 community during 1989 was still dominated by (NUSCO 1988a). High abundances of these deposit-feeding polychaetes and molluscs rather - species have also been associated with disturbance than the suspension feeding: species prevalent and recovery processes in LIS (McCall 1977; before the disturbance. Recovery of the IN Rhoads et al.1978); their tubes help stabilize community is proceeding slowly, and similar to sediments and allow for recolonization of other dredged sites, community composition and organisms that were dominant prior to disturbance abundance since the disturbance has exhibited high ! (McCall 1977). As with AI. ambiscia, the temporal variability (Kaplan et al.1974; Swartz et al.1980; fluctuations observed in these amphipod species Nichols 1985). Over the last 2 years, visual I occurred on a regional wide basis, and as such, observations by divers indicate that sediments in L were not considered indicative of power plant this area have begun to stabilize; the. lowered [ impacts. silt / clay levels observed in 1989 also suggests that l l Benthic Infauna 177 t
recovery is continuing. In an area within the therfral plume created under 3-unit operating condnions (NUSCO 1988b). Power plant impacts related to Unit 3 start up Power plant related impacts at this station were and 3 untt operations were evident during 1989 at first observed in 1986, when silty sediments, the EF and JC stations. The EF station is located scoured from the Unit 3 discharge cut, were approximately 100 m offshore from the quarry transported to and deposited in the area of the JC discharge cut into LIS. Sediments and infaunal station (NUSCO 1988a). This fine material was communitics in this area are exposed to the most easily suspended (by wind-induced wave direct power plant induced environmental changes turbulenec) producing turbid conditions and a (e.g., scour, temperature increases, chemical and highly unstable sediment surface. Concurrent with heavy metal additions). Impacts related to Unit 3 sedimentalogical changes, we observed significant start-up were reported in 1986 (NUSCO 1987). changes in the infaunal community, including Since Unit 3 start up, grain size increased and decreases in the abundance of oligochactes, A. , silt / clay content decreased, and the infaunal catherinae and P. crimius (NUSCO 1989). community shifted to an oligochacte dominated assemblage, while abundances - of previously During 1989, JC sediments still contained dominant deposit feeding species such as Tellinc significantly higher amounts of silt / clay than during agilis, Polycimes eximius and Aricidea catherine the 2 unit period. Values during this year
- significantly declined, exhibited less seasonal variability than those
. immediately after the siltation event and suggest .
There are several potential causes for the that stabilization is occurring. In' addition, observed infaunal changes at EF. Because infaunal observations by divers during sample collection species are ek)scly tied to sediments for food and indicate that bottom water turbidity has decreased shelter (Sanders 1958; Gaston et al.1988), the in the area of the station. Results in 1989 revealed decline in surface and near-surface deposit feeders trends similar to those observed in other 3. unit (A. catherinae, P. cximius, Tellina agilis) and years (l.c., oligochacte abundance has decreased increase in sub-surface forms (particularly while abundances of the deposit feeding mollusc, oligochactes) might be a response to changes in Nucula proxima and the polychaete Lumbrineris food availability (Gaston et al. 1988). The tenuis have increased). However, the abundance of increased abundance of oligochaetes observed at Polvcimes _ crimius and particularly Ariciden EF during our study has also been noted in other catherinae have increased relative to values power plant discharges,(Aston 1973; Gallup et al. observed in 1986 and 1987 after the sedimentation 1975; Lenat 1978; Jordan and Sutton 1985). In event. addition, a recent study reported that oligochactes were abundant within mussel (Myrilus cdulis) reefs To date, power plant related impacts at JC, (Commito and Boncavage 1989). Mussel reefs appear largely attributable to the one-time siltation i have become a prominent feature of the bottom event which occurred immediately after Unit 3 ! areas at the discharge cut into LIS, presumably in start up. In contrast to the EF station, where a response to increased food availability due to reduction in silt (and thus food resources) was increased current created by the 3. unit discharge, believed the cause for observed reductions in P. These reefs provide an indirect source of food (l.c., crimius and A. catherinae at JC, the decreases in biodeposition), as well as refuges from predation these taxa and reduced abundances of oligochactes and disturbance (Commito and Boncavage 1989), at this station nre probably reflecting the negative Furthermore, juvenile oligochactes emerge from influence of siltation. Siltation of bottom areas cocoons and directly enter sediments (Hunter and can result in burial of resident populations (Turk Arthur 1978); this reproductive strategy would and Risk 1981), instability of sediment surfaces-allow these organisms to inhabit and maintain (Rhoads and Young 1970; Rhoads and Young populations in areas of high current similar to the 1971; Jumars and Fauchald 1977), and cooling water discharge. interferences with normal Iceding modes (Rhoads 1 and Young 1970; Wildish and Kristmanson 1979), The JC station is located cast of the power plant These effects can produce population recruitment 178 Monitoring Studies,1989
. - ~- - ~ ~ . . - - - .
1 I patterss like those otscrved in JC Faunal Tubificidae (Oligochaeta, Annelida).- annipas indicate that conditions in 1989 at JC Hydrobiologia 42:225 242. i
-were more similar to 2. unit conditions than were l' other 3. unit years and thus remvery is probably Beukema, JJ.1979. Biomass and species richness ;
underway. However, the sk>w rate of recovery of the macrobenthic animals IMng on a Aldat i observed at IN following dredging suggests that flat area in the Dutch Wadden Sea: Effects of I complete recovery at JC could take I,cveral more a wvere winter. Neth J. Sea Res. 13:203 22). ]; years. Biernhaam, CM.1979. Intbence of sedimenta'y .l Conclusk>ns fa; tors on the 'diaributi6n - of benthic j amphipods of Fishers Island boond, > Power plant induced changes in the sedimentary Connecticut. J. Exp. Mar.Blol. Ecol. 38:201 223. j
- environment and infaunal communities werc .
observed during 19P9 along with natural changes in Boe6ch, D.F.1973. Clastification and community '! subtidal macrofauna. Declines ih the numerical structure of the Hampton Roads area Virginia, dominance of Medimmsrus ambistra and amphipod Mar. Biol. 21:226 244.. y] .- species were evident during 1989, and because they 1 occurred at.both potentially impacted and non. . R.J. Diaz, and R.W. Virnstein.1976. Effects
~
Impacted stations, were believed natural and not of ' tropical storm Agnca on ' soft. bottom f rchied to power plant operations. At IN,1989 macrobenthic communities of the James and j sampling continued to indicate slow recovery York estuaries and the lower Chesapeake Bay. .t i toward conditions prior to disturbance caused by Chesapeake Sci. 17:246 259. } Unit 3 intake e mstruction, impacts attributable to j Unit 3 start up and operation remained evident at . and R. Rosenburg.1982. Response to stress -! EF, where physical changes in environmental - in marine benthic communities. Pages 179 200 l i conditions (e.g., temperature and scour) are most in 0,W. Barrett and R. Rosenburg. eds. Stress - i direct. Although sedimentary characteristics at EF Effects on Natural Ecosystemui John Wiley,: { stabilized in 1989, infaunal community structure New York. ; and composition continued to show changesi At . JC, impacts of the 611tation associated with 3. unit Bousfield, E.L 1973. Shd!<mwales Wmmaridcan ]
, 6 tart.up continued in 1989, although results Amphipoda =of New England. Cornell Univ.
. 'i indicate that sediment stabilization and recovery of Presr, Ithaca, New York 312 pp, :
the infaunal community has begun. At present, L impacts caused by the initial r,cdimentation at this Carey, A.1%2. An ecological study of two benthic J l station precludes identification ofimpacts resulting animal populations in Long Island Sound. PhD. rom power : plant operational ' factors (c.g., thesis, Yale - University,n New Haven, 4 temperature cicvations or chemical additions). Ccnnecticut. 62 pp. : 4 C4 ntinued study after the scdimentarycnvironment returns to that observed during the 2 unit period Clifford H.T.. Land W. Sicphent,on.1975.- An would be necessary to fully assess impacts due to - Introduction to Numerical Classification.- ,! other plant operational factors. Acad(mic Press, New York,229 pp.. ; References Cited Commito,iJ.A..- and M. ! Boncavage. 1989.
~
Suspension-feeders and coexisting infauna: anL i Aller, R.C.1978. Experimental studies of changes enhancement counterexampic.T J. Exp.! Mar. I produced by deposit feeders on pore water, Biol. Ecoli 125:33 42. l sediment, and overlying water chemistry. Am. J. :; Sci. 278:11851234. - . Croker, R.A.1977. Macrofauna of northern New :[
. England marine sand:-1.ong term intertidal !
Aston, R.J.1973. Field and experimental studies -. structure. Pages 439-450 in B.C. CoullJed. o a.the effects of a power station effluent pn Ecology or Marinc Benthos. University of South - }[ l Benthic infauna '- 1791 .I a y
~;n , ,n :- - . , i- . , <+.-.,4- , , <
1 l Carolina Picss, Columbia. South Carolina. 467 Onliup, D.N., M. Hickman, and J. Rasmussen. l pp. 1975. Effects of thermal effluent and ! macrophyte harvesting on. the - benthos of Dauer D.M.1980. Population dynamics of the Alberta lake. Verh. Internat. Vercin. Limnol. j polychactous annelids of an intertidal habitat in 19 552 561. . upper Old Tampa Bay, florida. Int. Revue Ges. Hydrobiol. 65: 461 487. Onston, O.R., D.L 1ee, ar.d J.C Naci.1988. 1 Estuarine macrobenthos in Calcar,1cu take, ! Davey, J.T., and CL Ocorpe. 1986. Species Louisiana. Estuaties 11:192 200. ; interactkms in soft sediments: factors in the distribution of Nercis dircrs/ color in the Tamar Outon.- 0 R., and J.C Nasci.1988. Trophic i Estuary. Ophelia 26:151 164. 6tructure of macrobenthic communitics in the ! Cakasicu Estuary, Imuislana. Estuaries ! Demers, S., and: J.C %ctriault. 1987. -11:201 211, i Resuspension in th: shalkw sublittoral zone of a macrotidal estuarine environment: Wind Olcre, O. 1975. Population structure, food j influence. IJmnol. Oceanogr. 32:327 339. relations and ecological ' role of marine ! oligochactes, . with r,pecial reference to [ Doering, P.H.1989. On the contribution of the melobenthic species. Mar. Biol. 31:139156. i benthos to pelagic production.1. Mar, Res. ! 47:371 383. Goldhaber, M.B., R.C Aller, J.K. Cochran, J.K. t Rosenfield, C.S. Martens, and R.A. Berner. l Draper, N., and H. Smith.1981. Apptied regression 1977. Sulfate reduction, diffus,lon bioturbation analysis. John Wiley and S(ms, New York. 709 Long Island Sound sediments: Report of the - - pp. FOAM Group. Am. J. Sci. 277:19.k237. l Eleftheriou. A., and M. Nicholson.1975. The Oosner, K.L 1971. Guide to identification of i effects of exposure on beach fauna. Can. Bio. Marine ar.d Estuarinc _ invertebrates.- ; Mar.16:695 710. Wiley interscience. John Wiley and Soris, Inc. 693 pp. Emerron, CW.1989. Wind stress limitation of ; benthic sec(mdary production in sha!!ow, soft- Orassic, J.F., and J.P. Orassic.1974 - Opportunistic ; sedirteent communitics. Mar. Ecol. Prog. Scr. life histories and genetic systems in marinc
$3:65 77, benthic polychactes. J. Mar. Res. 32:253 284.
Fauchald, K.P., and P.A. Jumars.1979. The dict of Orcen,- R.H.1%9. Population dynamics and - worms: a study of polychacte feeding guilds. environmentalvariability Am.2ool.9:393 398. J t oceanogr. Mar. Biol. Ann. Rev. 17:193 284. _ llampson,'O.R.1971.- A species pair of the genus Filnt, R.W.1985. Long term estuarine variability Nucula (Bhalvia) from the cast coast of the and associated biological response. Estuaries United States. Proc. Malac. Soc, land. 39: j 8:159-169. 333 442. :
, and J.A. Younk.1983. Estuarine benthos: Holland, A.F. 1985. teng. term variation of .- =l long term community structure variations, macrobenthos in a meschaline region . of- -l Corpus Christi Bay. Texas. Estuaries 6:126-141. Chesapeake Bay. Estuaries 8:93113. ;
Folk, D.1974. Petrology of Sedimentary Rocks. , and J.M. Dean.1977 The community-Hempshill Publishing Company, Austin, Tczas. biology of intertidal macrofauna inhabiting' ! ! 182 pp, sahdbars in the North inlet arca of South i Carolina. Pages -423-438 in B.C Coull edi 1 180- Monitoring Studies,1989 l i
i l l Ecology of Marine Benthos. University of South Knelb, R.T.1988. Testing for indirect effects of l Carolina Press, Columbia, South Carolina. 467 predation in an intertidal soft. bottom ' pp. community. Ecology 69:1795 1805.
]
. and T.T. Polgar,1976. Seasonal changes in unce, O.N., and W.R. Williams.1%7. A general . j the structure of an intertidal community. Mar. thcory of classificatory sorting strategics,1. ,
Biol. 37:341348. liierarchical systems. Comput. J. 9:373 380. _ A.T. Shaughnessy, and M.H.111cgel.1987.
, lenat, . D.R. 1978. Effects of power. plant t/mg. term variation in meschaline Chesapeake operation on the littoral benthos of Belews Bay. macrobenthos: Spatial and temporal Lake, North Carolina. Pages $80 5%. in 11.H.
patterns. Estuaries 10:227 245. Thorb and J. W. Olbbons, eds. Energy and Environmental Stress in Aquatic Systems. U.S. Ilorn,- M.ll., and R.N. Olbson.1988. Intertidal Dept. of Energy Symposium Series 48, CONF. fishes. Sci. Am. 256:64 70, 7714. llull, S.C.1987. Macroalgal mats and species lxvinton, J.S.1973. Ocnctic variation in a gradient - abundanec: a field experiment. Estuar. Coast, of environmental variability: Marine Bivalvia and Shelf Sci. 25:519 532. (Mollusca). Science 180:75 76, 11unter, J., and D. R. Arthur.1978. Some aspects levinton, J.S., and S. Stewart. 1982. Marine of the ecology of Pchucolcr benedent Udekem succession: The effect of two deposit. feeding (Oligochacta: Tubificidae) in the Thames gastropod species on the population growth of Estuary. Estuar. Coast. Mar. Sci. 6:197 208. Paranais litoralis Muller J784 (Oligochacta). J. Exp. Mar. Biol. Ecol. $9:231241. Ilyland, J.L. EJ. Iloffman, and D.K. Phelps.1985. Differential tespcmses of two ncarshorc infaunal lorda, E., and . S.B, Salla.L 1986. A statistical - assemblages to experimental petroleum technique for analysis of environmental data additions. J. Mar. Res. 43:365 394, containing perkidic variance components. Ecol. Modeli 32:59 69. Jordan, R.A., and C.E. Sutton.1985. Oligohaline benthic invertebraic communitics at two MacGinitle, O.E. and . N. - MacGinitic, 1968. Chesapeake Bay power plants. Estuaries Natural llistory of Marine: Animals. 7:192 212. MaGraw.llill, New Yorkc 473 pp. Jumars, P.A., and K. Fauchald.1977. Between- Majecd, S.A.1987. Organic matter and biotic community contrasts in successful polychaetc indices on the beaches of North Brittany. Mar, feeding strategies. Pages 120 in B.C. Coull cd. Poll. Bull. 18:490-495. Ecology of Marine Benthos. University of South Carolina Press, Columbla, South Carolina. 467 Maurcr. D., and O. Aprill.1979, Intertidal benthic pp, invertebrates and sediment stability at the l mouth of ' Delawarc Bay, int. Rev. Ges. Hydrobiol Gl:379 403. Kaplan, E.fl., J.R. Welker, and M.G. Kraus.1974. Some effects of dredging on populations of Maurer, D., and W. leathem.1980, Dominant 7 macrobenthic organisms. Fish. Bull. 72:445 480. species of polychaetous annelids of Ocorges Bank. Mar. Ecol., Prog. Ser. 3:135 144. Kinner, P.C., and D. Maurer.1978. Polychaetous annelids of the Delaware Bay region. Fish. Bull. McCall, P.L 1977. Community pattern and 76:209 224. adaptive strategies of the infaunal benthos of-long Island Sound, J. Mar. Res. 35:221226. 4 Benthic Infauna 181
. . _. - _ . - .- . - _ - , , . - .. -. _- - . . . .=
~l 1
Moeller, P., L Pihl, and R. Rosenberg.1985. Oden, O.E. 1979. % c frest: water . littoral
- Benthic faunal energy flow and biological' melofauna in a South Carohna reservoir. j
. interaction in some shallow marine soft bottom - '
recch'ing thermal cifluemsi Freshwater. Biol. i habitats. Mar. Ecol. Prog. Scr. 27:109-121, 9:291 304. j
, Myers, A.C.1977. Sediment processing in a marinc l Persson, LE.1983. Temporal and' spatial variation ~ f subtidal sandy bottom community: 1. Physical in coastal.macrobenthic community structure,- ~j AspecisiJ. Mar, Res. 35:609 632. Hano Bay (Southern Baltic). J. Ihp. Mar. Biol?
- ~
- l Ecol. 68:277 293. j Nichols,F.H.1985. Abundaace nuctuations among .j Pettibone, M.H.1%3. Marine polychaete worms of - ;
honthic inverlebrates in two Pacific estuaries. Patuaries 8:1.%144. lthe' New > England region. Ic A(hroditidae - d through Trochochactidae. Buli.* .I.S. Nat. Mus. :j NUSCO (Northeast Utilitics Scrs.cc Company). - 227:1 356. , f 1981. ' . Benthic infauna. Pages 150 in - 'I Monitoring the marine environment of leng: Pielou, E.C. - - 1977. Mathematicel . ; Ecology. ! Island Sound at Millstone - Nuclear Power Station, Waierford, Connecticut. Annual
. Wiley.Interaclence, New York. 385 pp.
]
Report 19NO. . Pratt, S.D.1973. Benthic fauna. Pages 5.1470 in Coastal and Offshore imentory. Cape Hatteras
. 1985. Benthic Infauna. Pages . l.39 in to Nantucket Shoals. Marine Experimental:
Monitoring the marinc environment of long, Station. _ Marine - Publication Serled # ; 2.~. _ Island Sound at Millstone Nuclear . Power Graduate School of Oceanogiaphy. Univ, of . Station, -Waterford, Connecticut. Annual Rhode Island. Report 1984. .
' Price, LH., and J. Hylleberg,1982. Algal faunal -
. 1987. Benthic Infauna. Pages 151 in" . interactions in a mat of Ulvafenestrata in False 'i Monitoring the marine emironment of Long Bay, Washington. Ophelia 21:75-88. - >
lsland Sound at Millstone Nuclear Power _. . Station, Waterford, Conr.ecticut. Summary of Regnault, M., R. Boucher.Rodoni, O. Boucher,_ 1 studies prior to Unit 3 operation. Annual , and P. Lasserre.1988. Effects of macrofauna - J Report 1986. excretion L andV turbulence 1 on inorganic;
- nitrogenous exchanges at the water sediment- ,
_ . 1988n. Benthic Infauna. Pages 59117 in Interface. Cah. Biol. Mar. 29:427 444, l Monitoring the marine environment of long . Island Sound at Millstone Nuclear Power Reish, D.J.1%7. Relation of Capitella capitata to j Station, Waterford, Connecticut nrec. unit waste: discharge of L biologic origin.- Pages ~; operational studies 1986 1987. 195 200 in J C.M. Tarzwell, ed.- Biological ;; problems 'in water pollution.LU.S. Health' ti
,,__,1988b. Hydrothermal Studies. Pages 323 Service, q
354 in Monitoring the marine emironment of .i long Island Sound at Millstone Nuclear Powcr . . : 1973. - De ' use of f benthic animals - in i l monitoring ihe marine environment. J. Emiron. i Station. Waterford, Connecticuti Three unit Plann. Pollut. Control 1:32 38. i operational studies 1986 1987i .j Rhoads, D.C., P.L McCall, and J. Yi Yingst.1978. {
.1989. Benthic Infauna. Pages 38 98 in Disturbance and production on the estuarine ]
Monitoring the marine emironment of long scarloor. Am. Sci. 66:577 586. i Island Sound at Millstone Nuclear Power : Station, .Waterford. - Connecticut. Annual ' Rhoads, D.C., . and D.K. Young. ~ 1970.E The -. ! Report 1988. Influence ;of-' deposit feeding organisms on j if 182 Monitoring Studies,1989 j A y 1
, .j
. _ -. _ _ __ _ __ - . _ _ _ . . a
I sediment stability and community trophic Sedentaria). Amerind Publishing Co. Pvt. Ltd., structure. J. Mar. Res. 28:150-178. New Delhi. 212 pp.
,1971. Animal. sediment relations in Cape Swartz, R.C, W.A. DeBen, F.A. Cole, and LC Cat Bay, Massachusetts 11. , Reworking by Bentsen.1980. Recovery of the macrobenthos Molpadia politica (Ilolothuroidea). Mar. Biol. at a dredge site in Yaquina Bay, Oregon. Pages 11:255 261. 391408 in R.A. Baker, ed. Contaminants and Sediments, Vol. 2.' Ann Arbor Science Rice, D.L. T.S. Blanchi, and E.II. Roper.1986. Publisher, Inc., Ann Arbor, Mich.
Experimental st udies of sediment reworking and growth of Scoloplos spp.- (Orbiniidae . Tourtellotte, 0.11., and D.M. Dauer. 1983. Polychacta). Mar. Ecol. Prog. Scr. 30:919. Macrobenthic communitics of the lower Chesapeake Bay. 11. Lynnhaven Roads, . Richards, S.W.1963. The demersal fish population Lynnhaven Bay, Broad Bay and Linkhorn Bay, of long Island Sound. Bull Bingham Oceangr. Int. Rev. Oes, liydrobiol. 68:59 72. Coll. 8:1 101. Turk, T.R., and M.J. Risk. 1981. Effects of Sanders,ll.L 1958. Oceanography of long Island sedimentation on infaunal- invertebrate Sound 19521954. X. The biology of marine populations of Cobequid Bay, Bay of Fundy, bottom communitics. Bull. Bingham Can. J. Fish. Aquat. Sci. 38:642 648. Oceanographic Collection. XV:345 413. Warwick, R.M.1986. A new method for detecting
. E.M. Goudsmit E.L Mills, and 0.R. pollution cifcets on marine macrobenthic llampson.1%2. A study of the intertidal fauna communities. Mar. Biol. 92:557 562, of Barnstable liarbor, Massachusetts. Limnol.
Oceanogr. 7:63 79. .1988. Effects on community structure of a pollutant. gradient. introduction. Mar. Ecol.
, J.F, Grassic, O.R. llampson, LS. Morse, S. Prog. Scr. 46:149.
Garner. Price, and CC Jones.1980. Anatomy of an oil spill: Imng. term effects from the , T.ll. Pearson, and RuswgSyuni. 1987. grounding of the barge ' Florida
- off West Detection of pollution effects on marine Falmou'h, Masochusetts. J. Mar. Res. macrobenthos: further evaluation of the species 35t:265 380. abundance biomass method. Mar. Diol.
95:193 200. Smith, R.1964. Keys to marine invertebrates of the Woods Ilale region. R.I. S.T!!h, ed. No. I1. Wasa, M.L 1%7. Biological and physiological basis Systematics. Ecology Program, Marine of indicetor organisms and communities 11. Biological Laboratory, Woods liole, Indicators of pollution. Pages 271283 in T.A. Massachusetts. 208 pp. Olsen and E.JJ Burgers, eds. Pollution and Marine Ecology. Interscience Publ., N.Y. Soulsby, P.O., D. Lowthlon, and M. liouston.1982. Watling, L 1975. Analysis of structural variations Effects of macroalgal mats on the ecology of in a shallow estuarine deposit. feeding intertidal mudflats. Mar. Poll. Bull. 13:162 166. community. J. Exp. Mar. Biol. Ecol. 19:275 313. Stanley, S.M.1970. The relation of shcIl form to Watzin, M. C 1986. Larval settlement into marine life habits in the Bivalvia (Mollusca). Ocol. Soc. soft. sediment systems: Interactions with . the Amer. Mem. 125: 1 296. melofauna. J. Exp. Mar. Biol. Ecol. 98:65113. Strelzov, V.E.1979. Polychacte worms of the Wells, ii.W., and I.E. Oray.1964. Polychactous family Paraonidac Cerruti,1909 (Polychacta, annelids of the Cape liatteras area. J. Elisha Benthic Infauna = 183
Mitchell Sci. Soc. 67:133161. Whittatch, R.B.1977. Seasonal changes in the community structure of the macrobenthos inhabiting the intertidal Sand and mud flats of Barnstable llarbor, Manachusetts. Biol. Bull. 152:274 294. Wildish, D.J., and D.D. Kristmanson.1979. Tidal energy and sublittoral macrobenthic animals in estuaries. J. Fish. Res. Iloard Can. 36:1197 1206. Withers, R.O., and Cil. Thorpc.1978. The macrobenthos inhabiting sandbanks in langstonc liarbour, llampshire. J. Nat 111st. 12:445-455. Wo( din, S.A.1982. Browsing: important in marine sedimentary environments? Spionid polychacte examples. J. Exp. Mar. Biol. Eco!. 6(h35-45. Young. M.W., and D.K. Young.1982. Marine macrobenthos as indicators of environmental stre.u. Pages $27 539 in G.F. Mayer, ed. Ecological Stress and the New York Bight: Science and Management. Proceedings of the symposium; 1979 June 10-15; New York, New York. Estuarine Research Federation, Columbia, S.C. 715 pp. Zeitu.chel, B.1980. Sedimen!. water interactions in nutrient dynamics. Pages 195 218 in K.R. Tenore and B.C. Coull, eds. Benthic Dynamics. Univeralty of South Carolina Picss, Columbia, South Carolina. 461 pp. i 184 Monitoring Studies,1989
1 Contents Rocky Intertidal Studies ....................................... 187 Introd uction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 Qualitative Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 Abundance Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 Recolonization Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 Ascophyllum nodosum Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . 189 Da ta An alysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 Qualitative Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 Abundance Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198 Bam acles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198 Fucus ...................................... 200 Ch on dn ts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 Similarity Dendrograms . . . . . . . . . . . . . . . . . . . . . . . . . . 204 Recolonization Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205 Ascophythtm nodosum Studies . . . . . . . . . . . . . . . . . . . . . . . . . . 210 G rowt h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 M or tality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212 S u m m a ry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214 References Cited .......................................215 l l
Rocky Intertidal Studies qualitative algal sampling, abundance (percentage introduellon mver) measurements of intertidal organisms, recolonization studies, and studies of Ascophy#um Species assemblages on rocky shores interact nodosum, whose growth has been shown to with physical and biological factors to produce respond to environmental changes. patterns of mnation and community organization that are almost universal (Stephenson and This report discusses results of studies Stephenson 1949). Different components of the performed during the 1989 sampling year community exhibit different responses to (October 1988-September 1989), which are environmental conditions, e.g., perennial algae and compared to 3 unit operttional studies to date long livtd kessile invertebrates are continuosly (March 1986-September 1989), and to 2 unit exposed to potential impacts, and integrate their operational studies (March 1979-February 1986). effects over time, whereas motile species and short lived ephemeral algae can quickly change blaterials and hiethtxis in abundance with changing conditions. A large body of descriptive and experimental rescarch , exists that examines interrelationships among Qualitative Snmph,ng ' rocky shore species, and between blotic and - ablotic components of the communitics (Connell Qualitative algal collections were made 1%1, 19751 Dayton 1971). The rocky shore monthly at nine rocky intertidal stations (Pg.1). habitat is phpically stable and casily accessible, These stations arc, in order of most to least and rocky intertidal communities are among the exposed to prevailing winds and storin forcc4 Day most productive and most extensively studied of Point (BP), Fox Island Exposed (FE), Millsene marine ecosystems (!xwis 1964; Mann 1973). All Point (MP), 'I\votrec Ish,nd (TP), White Point of these factors contribute to the utility of rocky (WP), Seaside Exposed (SE), Seaside Sheltered , intertidal environmental monitoring. For (SS), Olants Neck (ON), and Fox island Sheltered example, analyses of rocky shore communitics (FS)- The MP and 'IT stations were added in + have been used to assess impacts associated with September 1981; all others have been sampled > many fonns of pollution, e.g., thermal (Vadas et since March 1979 Collections made prior to al.1976, Wilec et al.1978), sewage (Murray and March 1986 represented 2, unit operating Littler 1978), and oil spilk (Southward and mnditions; 3 unit collections were made after that Southward 1978). tline. The primary objectives of the NUSCO Rocky The FE station is approximately 100 m cast of ! Intertidal Studies are to determine whether the MNPS discharges, and directly exposed to the differences exist among communitics at sites in thermal plume (during part of the tidal cycle); FS, the Millstone region, whether these differences WP, TP, and MP are between 300 and 1700 m um be attributed to construction and operation of from the discharges, and potentially impacted by MNPS, and whether changes in these differences the plume, Stations at ON, SE, and SS are have occurred since Unit 3 began operation. To considered to be unaffected by MNPS operation. achieve these objectives, studies were designed and implemented to identify the attached plant Qualitative collections characterized the flora and animal species found on nearby rocky shores, at each site, during cach sampling period. Algal to identify and quantify temporal and spatial samples wrc identified fresh or after short term e patterns of occurrence and abundance of these freezing. Voucher specimens were preserved species, and to identify the physical and biological using various methods: in saturated Nacl brine, factors that induce variability in local rocky as dried herbarium mounts, or on microscope intertidal communitics. These studies include, slides. 1 Rocky Intertidal Studies 187
a .a i r sqnd
- d. .
,h g,s p o
I North 3 i 1)m f 'I O. Tmi ! r i f ~ V) I
.l 40%g (gg uNes l
u \*m,,ie n, l krN ';
"<> t m g Ti
}
l i f lig.1. twaiton or the MNPS neky intenidal sampling sites: oNeoiants Neck, HP=Ilay Point, MP= Millstone Point IT.=iu tilatwl. ! D umed,11s=I% i taland Shchered,1T=1woitec Island WP= White hdnt, sE=$catide lapmed, $$*Reaside $hehered. [
't' Abundance Measurement that approximately corresponded to their actual substrutum coverage. Each quadrat wcs antigned j
. The abundance of rocky intertidal organisms to a ynne based on its tidul heighti Zonc 1 (high was expressed as percentage of substratum cover, hetettidal), Zone 2 (mid intertidal), and Zone 3 i Al cach qualitative collection station except *lT (low intertidal).. l (because of insuf0cient exposed bedrock), five permanent strip transects were - t;stablished Recolonir.ation Studies ,
perpendicular to the water line, one half meter j wide and extending from .Mean Iligh Watet to Recoloninnlon. transect experiments were ; Mean inw Water levels.' Each transcci was designed to determine rates and patterns of . subdivided into 0.5 m x 0.5 m quadrats sind was recolontration following substratum denudation at - : non destructively sampled six times per year, in four i.tations: FE, FS, WP, and ON, Sample odd numbered months (or a total of 22 times in design included two pairs of station 6 with similar ;
'the Unit 3 operational period to date). As there degrecs of wave exposure: cxposed at FE and WP, ;
were no experimental manipulations, these are and sheltered at ON and FS. The Fox island - ' considered ' undisturbed' transects. The- total - stailons, because of their proximity to the MNPS , number of quadrats in each transect depended on discharge,' were considered to be potentially { the slope of the transect.. The permninge of Limpacted sites, while WP and ON were classified ;
~ , a ambatratum covet of all organisms and remainin! / . , as reference stations (hydrographic ' modeling-
-t
' free Japace in. 6ach quadrat was subjectively ' ' indicates that the 3. unit. thermal plume will
, determined and recorded. 'Understory organisms, extend past White Point (NUSCO 19Ma), but to -
or apocles that were partially or totally obscured ~ date, no thermal incursion has been recorded in- l
~ by the canopy layer, were assigned a percentage
~
the area of the WP recolonization studies) - ! J lM. Moniloting Siudion,' 1989< l
, ,f .-y ,
)
, J -- ,
y
/\
g North l3
, meters ,15,0 fe'et $0'O Effluent s Quarry
[ new cut FC N I prsginol cut
\
MP lig. 2. Detall map of the MNPS vicinity: I'O = original cagwrimental A.icry>lt dhsrn site (197944), l'N = nes esperimental A.ictyshyllwn site (1983.prearnt).- Three transects were established at each station, previous reports) located caf 75 m cast of the - one half meter wide and extending from Mean original Millstonc quarry cut (Fig. 2) from 1979-liigh Water to Mean Low Water levels. Each 1984. Monitoring of Ascophyllum has continued-transect was r, craped free of attached algae and to present .at ON' and WP. ' Arcophyllum was
' invertebrates and burned with a liquid petroleum climinated from FO in summer 1984 by exposure gas torch. All recWonization transects were to cicvated water temperatures from tne thermal-sampled monthly in the same manner as described plume discharged through two quarry cuts; for undisturtml transects. During the 2 funit populationf at WP and ON were not aftected operational period, tecolonization experiments (NUSCO 1985). . A . s_ccond , experimental were begun in April 1979, and again in - Ascophyllum station (FNi Fox it. land New, Fig. 2) -
September .1981 at the same transects, to was established in spring 1985 between FE and determine the effect of seasonal denuding on FS (Fig. 2, ca. 250 m from the quarry discharges, ; recolontration. Autumn denudings (September northeast of the Fox Island Exposed sampling - 1986) were re established during the Unit 3 - : site). - . FN wasE the closest . station 110 the-operational period, to assess possible 3 unit discharges that { supported 1. an Ascophyllum effects on recolonization. population, following the loss of this species from -- FO. Ascophyllum nodosum Studies . Ascophyllum plants. were measured. monthly ; Growth and mortality of tagged individuals of- froml April to the following April, after onset of the perennial brovn alga, Ascophyllum nafosum,- new vesicle formation. At each sstation, fifty L were studied at two reference stations (ON,6.5- plants were marked at their ' bases with a-
= km west of the discharge and WP,1.5 km cast of - numbered plastic tag, and five apices _ on_ cach the discharge, Fig.1) and an experimental station - plant were marked with _ colored cable' tics?
l (FO, Fox island-Old, referred to as FL 'in Linear growth was dciermined by measurements Rocky InterJdd Studies - 189 u
m e-i{ made from the top of the most recently formed A' Compertz growth curve was fitted to vesicle to the apes of the developing axis, or . Ascephyllum ' length data using non linear spices if branching had occurred. Monthly regression methods (Draper and Smith,1981). measuremmat of ta388d Plants began in June; in The Comports function has three parameters; as
- April and May, ves6cles were not large enough to they apply to Aseqphyitum -growth, a represents be tagged, and five tips were measured on each of the symptote, or total increase for the growing 50 randomly chosen plants. Imt tags were not season, and A and a determine the scaling and.
replaced, and the pattern of loss was need as a shape of the curve. Together, these _ last two measure of mortality. Las of the entire plant - parameters specify the location of the inflection-was assumed when both the bene tag and up tags point of the growth curve, the point at.which - were missing. Tip survival was based _ on the length is increasing most rapidly. Orowth curve number of remaining tip tags.- - parameters were competed among: years and stations using 2 sample t. tats (e=0.05). Orowth - Data Analysis and mortality data for the 1988 89 growing season c were plotted against the mean of 2. unit (1979 For qualitative algal collections, a percent. 1986) and. 3. unit (19861989) operational data, frequency of occurrence was calculated, based on Beaune the FN station was established in,198$,' the percentage of collections in which each . 2.unk operational data from this' site included : species was. found, out of all possible collections only the 1985 86 growing season._ Data from the' (e.g., at a station, in a month, during 2. unit or 3 original Fox laland Ascophyllum station (FO) were unit operation). 1For each - station / year included separately, and illustrate the effects oni combination, a frequency of occurrence index was the Ascophyflum population: associated.with the - determined, based on the number of times that opening of the second quarry cut.- each species was found at each station in each year. These indicos were 'uned ' to calculate Resulig and Dlacussion = simliarities among annual flores, using the Bray. Curtis formula (Clifford and Stephenson 1975): Qualitallye Sampling; p Sp -{pg 2tRin(X (X +Xg) X*) During the 1989. report period -(oct..19es. Sept. ' 1969), ' 121 species were; collected 'andJ
^
identified (Table 1). Annual species totals sincec where X is the frequency of occurrence index for have tensed from 101 species in 1979 to 132 : species ft) at' station ~(j), Xm. is the index at $Pecies in 1984 (Table 2). Both mtals occurred , station (k), and (n) is the number of species in: ring the period of 2. unit operation For the 3 common, A flexibleisorting (os 0.25), clustering unk ppendonal yean it date, annuat species . ta w must. mng ng homl20 @) m j algorithm.was applied to the resulting similarity ;1 mattin (Lance and Williams 1%7), ) Omau species meals fo(2 unk and
- 3. unit ' periods : were : 157 - and ? 141, Iespoedwly;
~
Quantitative' analyses included detstmination (Tak2h % dchnas,' by stadon, in N of abundance of interudal organisms, ' as. ' ***8' I"" 8 'EI'" O) '" "P N )E
* * "'N " " ""N I"" " '
percentage of substratum covered by each taxon. ; Unoccupied substrata _were classed as free spam, in August and anuary m 72 specia Jn Juneq For selected 'specia, these cover values were Simuar P8H8tn$ in species richness have been plotted against time, similarities of communities f* Ported in the past, for both 2 unit and 3 unit 4 among stations and between operadonal periods opendonahean WS O N, N)2 hmenj 3 were alculated using the Bray.Curtis coemcient! - 'PI*' N reds, 5 browns 7 greens). identified formult cited above, substituting untransformed! ' .dudng the 2.unk opendonal pedod, have not
- bun coHecte(since nu 1 began opendon .
^
?prcentages for frequency of occurrence ne same clustering algorithm was used to form i _ indices.' **#' "* *
- E' *
; uncommon and collected, on average, less than 4).
s tat 4do(gmupings ..
;190 Monitoring Studies,1989
- , =- -
T 1 i
, ,, , , ~ - ,
i i j i i l l l TABLE 1. Qualitative a17 31 collections (Mar. 1979-sen. le897 by conth, station, and fotel fee study, test thee. colums -l represent 2-unat (3/79-2/36) and 3-unit (3/86-9/891 subtotals, and all effluent guerry collections (3/79-9/897. Chlorophyts Jon Feb Mac Apr f*ay Jun Jul Aug Sep Oct f6ew Dee C'8 SP MP 77 FE FS W SE SS tot 2U StJ 0
-Ulothel= fleces 52 64 73 49 39 8 8 . 3 le 29 31 39 34 28 25 27 28 43 32 24 31 52 39 8
-Urospore penicilliformis 62 71 71 66 29 19 6 6 5 13 24 43 49 41 35 39 32 29 41 31 22 34 33 34 8 l
-Ueospore woreskjoldii 8 7 12 le 8 4 6 3 2 7 2 3 8 6 6 2 13 6 19 4 2 6 4 19 1
*ueospore collebens' 6 14 6 1 5 1 2 . . . . 2 4 6 3 2 4 1 2 2 4 3 4 2 1 Entocladia viridis 1 1 . I 1 1 1 . . 1 1 1 1 2 3 . . I 1 . . I 1 1 1 :
-Monostrona grevillei l' 53 56 63 51 9 1 1 1 . 5 5 24 23 19 24 16 28 29 21 24 22 23 21 2
-Monestrena pulcheum 13 36 85 92 83 11 2 . . 2 1 1 39 39 25 39 19 24 31 31 31 28 29 ZF 3
-Sem.,e.~.phe occia 5 16 32 49 54 28 6 . . . 2 3 25 21 31 24 15 4 16 7 6 16 17 13 3
-So g e=orpha seruginosa 3 1 5 17 24 18 4 2 2 . . . 19 19 15 1 5 5 9 5 2 7 6 8 1
*Codsolun gregarlun' . . . . . . 1 . . . . . 1 . . . . . . . . 9 9 . .
Censosiphon fulvescens . 1 . 3 2 2 1 . 2 . . . I 1 . . . 2 4 . 2 1 2 . 2
-811dingia ninino 56 52 48 57 69 66 54 69 61 53 49 53 60 53 77 72 73 13 64 46 67 57 54 63 6
-Blidingia nerginete 6 2 2 1 3 . . 2 1 1 2 2 . 1 2 1 2 1 2 2 2 1 1
. 11 15 15 34 47 43 26
-Enteronorpha eletheata 5 3 2 6 3 27 8 19 2 24 34 31 2 17 18 18 18 49
-Enteronorpha flemuosa 34 38 34 35 39 41 43 35 57 55 55 36 47 43 41 28 72 37 55 14 37 42 38 49 74
-Enteronorpha preenlandica 3 ? e 19 8 5 1 . . . I 7 4 14 4 3 2 3 3 2 *
- 6 1 2
-Enteronorpha antestinalis 23 23 32 49 42 42 44 46 33 28 29 19 59 39 41 17 28 22 51 IS 39 33 34 39 29
-Enteronorpha linre 48 34 40 63 69 67 65 57 61 79 55 49 53 76 78 43 74 39 68 43 37 57 55 58 49
-Enteronorpha prolifera 37 35 25 26 27 32 19 27 29 42 38 44 38 39 28 24 28 28 45 17 36 31 37 3
29 44
-Enteronorpha torta 1 . . . 2 8 5 4 1 3 1 . 4 1 1 1 2- 5 5 . 2 2 1 4
-Enteronorphe ralfs11 . 1 1 . 1 le 9 4 3 2 1 . 5 1 1 2 3 ? 3 1 . 3 2 3 .
Percursaria percursa 1 . 1 3 2 5 2 1 2 2 . . 2 2 . . 1 6 4 . 1 2 2 1 3
-Ulva lactuca 95 99 78 84 89 99 96 94 ?8 99 97 95 98 92 96 95 94 91 96 88 86 93 9 92 94 62 Ulvaria owysperam 1 I 1 . . . . . . . . 1 . . . . . . 2 9 . 2 24 23. 19 24 2* 26 39 25 25 24 17 29 59 l
-Frasiola siipitate 1 2 89 1 1 1 71 13 to 24 25 .
-Cheetomorphs linum 77 56 35 32 51 86 92 94 91 91 79 69 62 78 75 89 51 63 73 78 81 71 7; 64 7 Chaetonorpha nelagonlue . 1 . . . . . . . . . . 1 . . . . . . . . 9 9 . 1
-Chaetonorpha seres 29 28 28 28 39 29 41 33 38 31 34 35 39 25 42 5 69 44 51 3 14 32 29 37 12 l
Clodophors albida . . 1 3 6 6 19 6 8 2 2 1 3 2 3 . 5 6 19 2 4 4 6 1 le i -Clodophers flevuoss 13 1 3 8 18 38 55 34 31 39 14 9 12 31 39 18 29 29 28 19 17 21 16 31 2 Cladophora glaucescens . . . . I 1 1 1 . . . . . . 1 . . . 2 . . 9 1 . 2 Cladophora leetevirens . . . I 1 2 3 . 2 1 . . . . 1 . . 1 2 1 4 1 1 9 .
-Cladophora refracta 7 6 3 1 5 26 23 17 18 27 13 16 6 28 IS 6 15 9 17 14 8 14 18 6 .
-Cledophore serices 13 5 9 25 45 32 31 37 29 21 15 17 28 17 11 3 35 38 39 8 18 23 24 21 39 70 *Cled W~.. crystallina' . . . . . I 1 . . . . . . . . . . . . 2 .
- 9 . 2 Cladophora hutchinsiae 1 3 3 3 8 9 9 11 19 19 7 2 6 2 19 3 9 6 9 2 9 6 7 5 .
Q7--Cladophora rupestris . I 1 1 5 5 6 4 . I 1 . 2 2 1 3 2 3 3 1 3 2 2 2 2
'<-Cledophora ruching-rl . . .' . I 1 2 5 3 1 1 . . . . . 6 3 2 .
8
. 1 9 8 19 21 16 3 19 4
---Rhizoeloniun riparlun 8 29 29 13 15 29 29 39 24 22 9 15 314 16 5 6 14 44 31 E *Rhizoclonium keeneri' 1 . 3 . 1 3 1 1 . . . 1 1 . . . 1 I 2 1 1 1 1 1 9 ;
3 1 1 2 1 1 Q thizocloniun fortuosus c.-Bryevsis plunose 8 2 2 1 16 13 11 9 6 7 6 5 8 29 4 5 4 4 6 6 6 8 ' C -Bryopsis hypnoides . . . . 3 6 13 8 5 7 5 3 6 3 2 4 6 4 4 3 6 4 3 7 5 P -Derbesia carina 5 5 2 5 1 1 3 3 9 8 9 5 2 . 3 29 5 1 . 2 4 6 2 28 ' US-Codium fragile 99 81 67 72 73 85. 86 88 89 91 87 85 82 81 81 ?6 199 99 85 62 79 83 83 82 52 J Values represent numbee of times found t.* absent; C:s a r.t, <1%). g Dash before species nano indicates thakitaswas a percentage found in 1989.of possible times found vs
gTASLE 1. feent.) w L %te Jon Feb Moe Ape Mer Jun Jul h g 3ew Oct New Dee GM 87 fr TT FE FS7 WP1 3E4 S36 tot 820 3U 9 2 27 3 2 2 2 3 6 8 1 <. 23 5 5 12 9 3 1 9 7 g Genietricheme elefeii Erythrotrichia e111 erie 38 16 12 It 15 le 9 19 31 49 31 21 35 19 11 17 31 19 25 9 18 21 22 18 13 o 1 1 1 8 7 2 2 6 2 1 4 4 2 2 2 3 2 3 4
-s-Erythrotrichio carnes 2 6 . . I .
1 2 1 2 1 6 r-Erythrocladio subintegre . . 1 . . 1 . 2 1 5 5 3 1 2 3 1 4 . . 6 3 4 1 3 2 1 6 9 7 6 2 9 5 2 7 2 2 3 4 4 3 5 6 o Erytt.copeltie discipere .
-Sangle strepurpures 63 78 83 81 29 13 4 6 3s 24 29 48 47 46 51 48 48 38 58 39 24 4e es 41 1e Porphyre leucesticta 56 73 74 76 57 27 13 8 8 27 24 29 44 31 63 45 41 33 48 35 28 39 34 49 16
- 4 Porphyre orbilicolis
- 47 58 77 83 89 65 49 40 25 19 28 352 57 39 581 58 68 43 311 681 31 519 SSe 511 18 . . .
9-Porphyee linearis . . 1 . . . . . . . . . . . . 8 e 1 C ib A ,; e sis coccinea 1 1 . 2 . . . . . . . . . . 1 . . 2 . . 1 2 1 3 1 2 1 ? 1 I. 2 2 8 1 b Audouine la purpures 2 2 . 2 2 1 1 . . . . . 7 3 -Audouinella secundeto 31 6 41 34 3 33 4 31 2 3s 2 23 3 16 1 161 312 15 6 14 333 452 33 2 173 172 29 2 224 24 3 23 2 26 3 31 3 17 1 It
-Audevinella deviesii .
8 15 13 le 19 14 11 9 2 6 le 11 9 21
-Audouinella seviana 13 6 12 12 is le 4 4 16 16 18 8 e e T 1 2 . . 1
$ Audouinella sp. . . . 1 .
1 2
. . 2 1 . . 9 9 9 1 e Audoulnelle desyse . . . . . .
1 12 9 17 1
-celidium erinele 12 9 8 le 11 le 12 12 14 16 16 17 29 1 . . 2 2 76 3 .
1 . . . . . t . 9 . Menelion helmintholdes . . . . . . . . . . . . . 2 39 2 21 27 36 16 15 16 2
-Bonneesisonia hanifere 7 9 15 17 29 49 3ae le 1 1 3 6 2 14 .
. . 2 9 e e .
'Traillielle intricata' . . 1 . . 1 . . . . . . . . . . . .
7 7 6 4 8 11 11 11 16 le 12 12 3 56 4 1 41 6 11 2 9 19 It ? 94
-Agordhielle subulata 9 14 le 2 7 9 5 6 14 2 21 8 le 5
-Polyides rotundus 5 8 1 5 9 5 8 11 11 .
3
-Cystoelonian purpureum 77 75 62 62 71 72 39 18 3 143 361 51 1
59 1 57 39 1 6s 69 397 46 62 47 58 521 60e 4eZ
-Gree 11 aria tikvehise 1 . . . . .
49 44. 40 38 33 34 31 27 2? 49 38 45 15 33 47 73 49 15 49 217 42 12 3613 46 15 2s9
-Ahnfeltie plicate 7 6 35
-Phy11ophora pee- h a ides 21 16 11 12 11 le 8 18 5 19 15 17 8 6 13 25 .
6 7 13 14 9 7 8 11 8 7 17 3 le 4 12 4
-Phy11ophors tranents le 15 8 5 6 9 8 6 .
-Chondrus crispus 97 97 97 97 ?7 97 ?8 98 97 95 97 97199 les ISS ISS 72 199 198 199 199 97 97 96 .
-rfestocseras stellatus 79 59 59 56 59 63 59 68 61 62 74 671 26 55 98 Its 11 29--77 ** .
'5 62 61 65 1 0 9 .
Petrocelas middendorfli . 1 5 1 6 2 1 2 2 2 1
. 2 2 1 8 2 2 1 .
Pho:fophysees georgii .
-Cors111na officinalis 63 64 55 56 56 58 57 63 58 45 59 67 2 es 99 32 93 89 84 32 24 68 6e el .
1
-Dunentis contorte 45 58 77 81 78 41 5 2 1 . I 9 39 17 36 58 17 45 32 38 42 34 35 31 1 . . 1 . 1 . . . . e e . .
Gleiosiphonia copi11eris I . . . . . . . . . . 3 6 5 6 4
-Choroccolsw polysiphoniae 8 13 8 8 8 2 4 3 2 3 1 8 18 21 4 2 2 . . .
5 1 1 1 2 3 5 1 2 1 . . 14 . I 2 . 1 2 2 2 . M11denbrandle rubra . . . 6 39 21 56 29 33 22
-Palnerie peineta 28- 33 39 34 4 33 37 3s 27 22 13 26 29 38 28 13 71 4 35 67 74 72 68 47 33 28 19 34 6
35- 35 56 27 45 35 37 315 2
-Chenpla pervuis 28 19 12 2 7 1 17 5 1 4 17 13 13 2 2 9 19 6
-Lonentaris boileyana 2 . . . . 1 5 25 38 22 8 6 9 5 7 2 1 7 6 12 6 1 1 3 4 2 5 3 3 3 2 9 2 3
-Lenentaria elsvolloss 8 2 2 2 2 3 . I 1 . . 5 . . 3 . 2 1 1 1 1
-Lonentaris v. A .efs . . . . .
2 1 1 1 2 3 1 1 3 2 2 2 2 1 2
-Antithannien enericenue 1 1 3 3 3 . 1 . 1 .
-Aetithannien erweistu, 44 26 ISe ' 16 13 18 1
46 63 3 60 69 69 I 55 2 36 58 2 39 43. 32 38 2 255 1 29 422 148 431 361 25 . Antithennion pylaisael 2 . . I . . . . . . . 8 le 13- . 37 3
-Anti'thannion sp. 16 16 il 4 6 6 11 19 24 8 17 19 4 13 31 21 14 le 13 6 Callithennion m ,4vsue . . . . 1 . 4 5 5 3 . . 5 1 1 2 1- 3 1 1 2 2 .
5 1 3 1 . I 6 17 29 14 12 6 7 4 7 6 21 9 8 2 6 8 9 6 19
-Callithsonien rescue
-Callithemnion tetregon.um 47 35 23 26 17 9 173 28 32 41 55 38 252 333 43 45. 34. 19 36 15. 23' 33 I 391 12 1 s 12 Callithamnion byssoides ." . . . . . 2 1 . . . . . . .
-Callithannion baileyi 8 7 4
- 2 2 8 6 8 12 16 9 6 16 21 15 . 3 7 . 2 7 1 18 7 1 2 3 2 3 6 9 2 3 2 2 2 2 3 1 .
-Cerenium deslongchampli 5 2 1 1 . . -
. 25. 62 49 42
-Cers=1un diaphanus 5 . . 1 . 9 8 13 28 2 28 7' 9 26 17 29 17 18 14 31
-Cerenturn rubeus 88 88 72 76 84 ?8 92 86 92 1 98 91 87 84 .
97 7E1 94. 81. 88 94 83 85 86e 88e 83 34 Cecaelun festigiatua . . . . . . . . . 6
-3perpothennion repens 58 33 29 24 22 29 27 48 33 (7. 45 66 46 54 29 35 19 24 69 32 46 48 2 432 352 9 1 1 1 3 9 3 2 3 12 2 . 1 . 2 1 . .
-3pyridio filonentoss . . . .
1 1 1 3 6 2 11 2 11 4 4 4 19
-Crinne111e emericanuse 2" . I 1 1 4 9 8 9 19 7 3
4 9 5 8 4 3 4 6 6 2 . I le 1 2 16 4 9 5 5 3 . 1
-Phycodrys rubens
-Desya baillouviens 7 1 . 1 . . 5 32 24 22 28 13 8. 19 2 8 29 15 14 2 11 le 12 7 49
. . 2 4 3 . . 4 1 . 1 . 1 . . 1 1 1 0 .
-Chondrie sedifolia . . . .
TABLE 1. (cont.) Rhodophyte (cont.)
-Chondria baileyana Jan 1 Feb ffar 1
Apr PSy 1 Jun Jul Aug Sep Cet Nov Dee CN BP MP T7 FE FS UP SE SS tot 2U 3U 9
. . . . 3 14 8 3 6 3 8 3 2 2 1 3 Chondria tenuissien . . . 1 . . 2 3 2 .
. 4 I 2
. 3 2 .
Chondria dasyphylla . . . . . . . I 1 1 .
. . . . . . . . 1 . . . . . . 1 e e
-Polysiphonie denudate 1 1 1 2 1 4 2 6
-Polysiphonia harveyi
. 5 5 . 5 1 3 4- 2 4 1- 2 2 3 2 52
-Polysiphonia lanosa 53 38 17 19. 14 44 72 77 75 56 58 52 45 46 46 43 61 45 58L41 48 47 58 28 51
-Polysiphonia nigra 78 5 79 8 49 9 42 71 le le 14 69 651 69 2 67 1 69 6 793 74 6 78 98 6 11 les 2 47 2 31 2 35 86 5 16
~ 57 6
948 687 68 69 .
-Polysiphonia nigrescens 16 17 1; 25 14 26 19 18 17 23 21 29 19 29 7 5 2
-Polysiphonia urceolata 29 15 Zv 39 47 26 12 4 3 4 le 14 15 53 9 28 19 21 15 5 1 2 6 35 18 18 19 16 3 39 4 9 17 to 11 8 Polysiphonia elongata . . . . . 1 . 1 . . 1 2 . . . 1 . . 3 e 1
-Polysiphonia fitralloss 5 1 1 3 Is 3 1
-Polysiphonia flexicaulis
. . . . . . . 1 4 3 . 2 1 1 2 2 8 7 1 . . . . . 1 . . . 1 1 2 1 1 2 e
-Polysiphonia novae-anglise . . 1 . 1 2 1
.Rhodomela confervoldes 76 6 6e 461431 34 7 23 8 54 2 75 82 I 83 1 91 1 ?!1 871 65 18 68 6 761 656 8e 61 74 57 65 68 63 75 42 3 2 5 5 8 5 7 2 1 Phaeophyta Jan Feb ttea Apr Play Jun Jul Aug Sep Oct Nov Dec GM BP ffP 77 FE F5 WP SE 33 tot 2U 3U C
-Ectocarpus fasciculatus
-Ectocarpus siliculosis 5 13 - 14 25 31 37 26 16 27 28 24 12 29 25 28 39 29 9 24 19 16 21 22 29 1 Estocarpus sp. 17 3 31 8 43 6 46 5 48 57 4 46 5 333 22 4 28 1 23 3 15 3 473 34 29 43 4 le 7 332 28 2 2 2 43 31 236 34 4 39 24 8
-Giffordia granulosa 3 2 2 4 5 8 2 5 2 .
. 4 1 5 2 4 2 5 5 6 2 3 1 2 3 3 3' 6
-Giffordia nitchellise 6 7 3 4 15 16 16 33 41 35 15 7 22 18 7 11 38 15 25 5 5 17 15 29 15
-Pilayella littoralis 19 15 25 35 48 32 11 13 le 22 le 15 58 7 3 23 6 58 29 6 7 21 22 29 2
-S m ge. tonentosue 13 26 44 31 17 1 2 4 . 8 1 3 15 18 13 16 12 6 13 14 9 13 13 13 Entonene accidioides . . . 2 1 . . . . . . . .. 2 . . . . . 1 . e ,
Acinetospora sp. . . 2 1 1 1 2 Feldnannia sp.
. . . . . . . . . . . . 1 . 9 1 . le
. . . . . . . . . 1 1 . . 1 . . 1 . . . . 9 e . .
-Ralfsia verrucosa 48 56 37 44 41 39 59 67 68 63 56 52 75 62 47 33 43 62 78 33 3* 52 52 53 .
-Elachista fucicola Halothrix lunbricalls 37 49 . I 62 1 71' 78
.. 5 862 75 1
77 78
. 1 59 1
44 33 72
. 1 673 64 1 611 57 44 652 71 552 621 61 65 .
. . . . 1 1 .
-Leathesia difformis . 1 . 13 25 32 29 le . . . . 17 6 26 5 12 5 15 1 2 9 8 13 .
-chorderia flagelliformis . . . 4 ' 18 38 29 25 15 5 1 2 12 26 17 13 4 2 22 8 5 12 14 8 .
Sphaerotrichia divaricata l' 1 3 6 1 I 1 3' Eudesne zosteree
. . . . . . . . . . 2 2 1 1 2 0 .
. . . . 1 . . . . . . . . 1 . . .... . . . O e . .
-Asperococcus fistulosus 12 5 2 3 1 2 2 2 4 1 2 4 1
-Desnotrichun undulatum 6
. . .. . . . 1 2 2 1 .
. ' 2 9 4 3 . . . 2 . 2 6 5 . 2 2 2 3 . 2 2 3 2 .
.- 2 3 . . . . . . 1 . . 1 I 1 1 2 1 1 1 E-Phaeosaccioncollinsii-
-Punctoria latifolia 2 '8 11 9- 5 9 1 . -3 5 6 4 6 2 8 4 8 5 5 3 5 5 4 2
X -Punciaria plantaginea 1- 3 2 1 4 5 5 3 -.3 1- 3 1 7 3 2 1 . 7 5 . 1 3 3 2 . Q -Petalonia
-Scytosiphon fascia lomantaria 71 85 74 99 86 81 68 le 3 12 48 66 56 72 67 58 54 55 69 53 35 57 57- 58 9 45 74 to 96 94 92 .77 16 -
3 7 16 31 41 78 57 48 46 61 59 47 36 54 56 51 6 5* Delaneres attenuate . 1 1 . . . . . . . . . . . 1 . . 1 . . e e . . g -Descerestia seulesta 9 8 8 13 12 le 8 4 5 7 13 5 7 2 3 21 3 6 18 8 ..9 8 8 le .
- -Desperestia viridis -1 3 25 48 48 34 1 1 1 Is 12 15' 26 6 19 76
-~C+-Chorda filun 2
. . . 9 19 13 14 12 2
. . . 8. 20 15 2 .. . . . -2 2 1 14 1 1 9 4 6 4 4 5 E-Chords tonentose .~ . 8 . 20 28 2 5 . . . . . 1 5 3 24 2 2 4 6 7 5 5 6
-Leninaria digitate 1s 1. 1 1- 2 . . 1 1 . .' 2 . . . le . . . . . I 1 1 .
(n-Laeineria longiervris 8 12 12 16- 13 .33 16 15 17 17 12 13 9 '2 9 52 1 2 21 17 17 14 12 17 . E -Laninaria saccharina 48 36 :53 60 83 84 81 76 69 57 58 ~ Se 65 69 61 . 99 54 48 65 ' 64 49 62 63 61 5 c.-3phecelacio cirrose 31 16 13 14 17 15 -19 22 26 38 34 48 49 28 8 3 54 36 29 4 4 23 22 24 2 E
-Sphaceleria forcigera . 1 . 1 . . I 1 1 . 1 . . . . 2 1 1 . -*
- 1 .
-Ascophyllun nodoson 94 '94 96 96~ 96 96 96 96 95 94 . 94 94 les les les Ice 5719e les les les 95 97 91 .
. Fucus distichus s edentatus 9 10 '12 16 10 3 1 1 . 1 3 3 5 5 14- 16 8- 4 2 5 1 6 8 3 .
. Fucus distichus s evenescens le 9 19 - 18 15 5 4 4 1 3. 7 . 7 13 3 23 4 4 7 6 9 8 le 5 .
- . Fucus spiralis 2 1 2 9 5 le 6 5 13 7 6 3 5 31 11 . 1 2 2 2 6 6 5 .
C -Fucus vesiculosus 98 98. 99 99 - 99109 ISO 199 98 ?8 f 98 98 ISO 198 les 198+ . 88109199 ISS 199 99 98 108 . Sargassun filipendula 1 1 1 l' 1 1 1 3< 2 1 1 1 . 1 . . II. . . . . 1 8 4 .
new to the Millstone shore arca were identified throughout this study has been laterpreted as during the 3 unit study period, Nemahon evidence that seasonal cycles of kical helminthoides (collected only once at BP, July environmental conditions have remained 1967), and Antithamnion sp., whose occurrence is consistent. Infrequent species, or those restricted described below, to only a few sites or months during the 2 unit operational period, hase generally been found Data in Tabic 1 represent percent. frequency with similar frequency during 3 unit operatkin. of species occurrence by month, by station, and Similarly, species with widespread distributions overall for 1979-1989, 2 unit and 3. unit prior to Unit 3 start up arc still found throughout operational studics, and for all efauent quarry the MNPS area, hence the close comparison. for collections. The flora of the Millstone area is 2-unit and 3-unit occurrence frequencies for most compaed partly of species common throughout species (Table 1). the year at most sites, some of which are perennials (long-lived individuals), e.g., Chondrus An exception to the generalization of similar-cristws and Mastocarpus sicllata (Rhodophyta), percent frequency occurrence during 2 unit vs. 3 Laminoria saccharina, Ascophyllum nalmum, unit operation is apparent in the recent addition - Fucus ecsiculosus (Phacophyta), and Codium to the Millstonc shorc flora of a small branched-fragile (Chlorophyta). Others are best described filamentous red alga, Antishamnion sp. This plant as ascasonal annualst individuals in this category was first collected in August 1986 al MP, and was are short. lived, with rapid reproductive turn over initially identified as Antirhamnioncila floccosa enabling population persistence, e.g., Ceramium (NUSCO 1988b). It has subsequently been rubrum and several Po@siphonia spp., Ectocarpus reassigned to the genus Antilhanmlon, but does siliculmus Ulra lacruca and several Enteromorpha not conform to existlng North American or spp. Other species show clear temporal European spoeles descriptions (C. Schneider, pers. (seasonal) and spatial (site-tpecific) patterns. comm.). Regardless of its origin, Antiihamnion Some of thesc species arc most common in late sp. has since been found at overy station (37% of winter / spring, such as Momurroma pulchrum, all 3 unit collectionst Tabic 1). Antirhamnion sp. Identified from more than 80% of all collections is mnsidered to be an addition to the local Dora, made in February, March, and April (Table 1). but its widespread distribution at mntrol and Other species characteristic of spring collections experimental stations males it unlikely that its . include Bangia atropurpurca, Avphyra leucmticto, appearance was related to p(mer plant operation. lkmontia consona, Pctalonia fascia, Sqtosiphon lomentaria, Monostroma grevillel, and 14 c(mtrast to such an arca wide phenomenon. Spongomorpha arcia. Similarly, a few kical an expected power piant effect would involve the species are typleally found when ambient water sudden appearance or disappearance of species temperatures are highest (AugeSep.), e.g., only at a station in close proximity to the MNPS Champia parvula, IMsya baillouviana, GJJordia aischarges. Such a Doristic change was remgnited mischcIIlac. Another component of the kical Dora at FE following the opening of the second quarly - includes species that show site spectacity. For cut (August 1983), amt has been ilescribed in exampic, Gelidium crinnic has been identified from previous reports (e.g., NUSCO 1987). Chondrus more than three quarters of the collections made etUpus and Ascophyllum nafosum were climinated at FS (97 of 127 collecdons,76%t Table 1); it from the FE study site by cicvated water was also relatively mmmon at ON (20% of all- temperatures resulting from 2-cut /2 unit colleethms) but rarc or absent at other stations operation. Conditions at FE changed again with (04%). Similarly, Prasiota stipitata was common the start up of Unit 3 (NUSCO 1989)t during 2 at 17, SE, and ON found in 89%,71%, and 50% cut /3 unit operation, Chondrus reappeared in July - of collections, respectively, but was infrequent (1- 1987, and has since maintained a small -- 13%) elsewhere in the MNPS area. population. A few small Ascyhyllum plants were first observed at FE in March 1989, and have also The mnsistency of patterns in spatial and persisted to date (Feb.1990). Long term survival temporal distribution of most kical species of C. crispus and A. mulosum at FE indicates that lethal water temperatures have not occurred since 194 Monitoring studies,1989 -
TAltl.E 2. Numter of slecus ty statkm, year, and devNon (persentages are in parenthenes). 2 unt; (3 79 to 2-86) and 3-unit (3-66 to 9-89) opersthmal summaries are included Each year in reprnented by collections from March to folkwing February, escept 19N9 whkh includes Oct.198R $rp.1989,
$ta. Div, 1979 19N0 1981 1982 1983 19k4 19R5 2 unit 19N6: 1987 ~ '1988 IW9' S-unit summary summary llP reds 32(44)- 34(4k) 4R(51) 40(47) M(42) 39(46) 3M45) 57(44) 33(43) 33(47) 2M(41) 31(43) 41(43) ,
brt=ns 16(22) 18(25) 24(25) 24(28)_18(22) 21(25) 20(27) M(27) 21(27): 17(24) 19(28) 19(26) 24(27)- greens 25(34) 19(27) 2N24) . 22(26) 28(35) 25(29) 20(27) 38(29)' D(30): 20(29) 21(31) 22(31) 29(30) total 73 71 95 '- 86 80 85 ^ _ 73 131 77 70 2 68 72 % i IE teds 34(44) 34(47) 32(41) ~ 3)(41) 29(41) 29(45) 21(42) $0(45) 22(35)'24(41) 25(40) 29(50) 39(43) brcens 18(23) 16(22) 22(2H) : 17(21) 17(24) '14(22) 10(20) 26G3)' 16(26) 12(20)- 19(30) 13(22) 22(24): greens 25(32) D(32) 24(31) 30(3R) 24(34)'22(34) 19(38) M(32) H 24(39) U(39) 19(30) ' 16(28)~ 29(32) total 77 73 78 80 70 65 - 50 112 62 $9 63 58 90 - 13 reds 33(46) 30(43) 29(40) 39(49) 39(49) 37(45) 2N(42) $4(44) 23(38) 23(40) 29(47) 2R(42) 3R(44) brtmns 16G2) 15(21) 21(29) 16(20) 16(20) 22(27) -15(23) 32(26) -16(27) 12(21) 13(21) 17(25) .20(23) gretns 23(32) 25(36) 2N32) 25(31) 24(30) 23(3) 23(35) 3R(31) 21(35): 2N40) 20(32) 22(33) . 28(33) . total 72 70 - 73 80 - 79 82 66 ' . 124 . 60 58z 62 67 86 ON reds 29(43) 34(45) 3N(44) 3N(45)- 37(45) 36(43) 34(44) 56(45) 27(41) 30(42) 34(41)~35(44) 42(42) brtmns 17(25) 18G4) 23(37) 20(24) 17(21) 20(24) 19(25) 30(24)'17(26) 1H(25) 22(27) 21(27) 27G7) greens 22(32) 2K31) 25G9) 27(32) 3(34) 28(33) 24(31)' 39(31) 22(33) 23(32) . 27(33) 23(29) 31(31)_
,l total 68 - 75 86 85 82 84 77 125 ' 66 91 83 79. 100.
. . l MP teds . .
.- 30(40) 33(43) 31(40) 31(44) 46(43) 29(33) 26(46) 26(39) 3(42) 42(46) y, brtens . . .
20(27) 22(29) 23(30) .18G4) 29(27) l 16(24) 12(21) fl9G9) 20(30) 26(28) greens . 25(33) 22(29) 23(30) 24(32) 32(30): 22(33)- 18(32) 21(32) 18(27) 24(26) tolai 75 . 77 77 73 .107. . 67 56 66 66 - 92
$!! rrds 27(46) 25(45) 34(48) 33(45) 32(46) 29(41) ' 28(44)' 48(44) ' 24(41) 25(46) ' 29(46). 29(43) 36(43) brtmns 15(25) 17(30) 19(27) 20(27) 15(22) 20G9) 15(25) 29(27) 15(25) 13(24)' 16(25) 17G5) 20(24) greens 17(29) 14G5) 1k(25) 20(27)--22(32) 21(30) 20(31) 32G9) 20(34) 16(30) " 18(29) 21(31)'27(33) total 59 56 71 73 69 - 70 63 109 $9 ' $4 - 67: 83 l
, SS reds 30(44) M(49) 40(47) 40(45) 40(47) y43(51) 30(44) $7(46) 29(45) ~ 35(52) 34($1) 33(45)347(48) -
brimus 16(24) 13(19) 2N27) 21G4) 23(27) 19G2) 17(25).31(25) 17G6) 13(19)- 11(16) 19(26) 22G3) ) greens 22(32) 22(32) 22(26) 27(31)'22(26) 23(27) 21(31)-' 36(29) ~ 19G9) ' 19G8)' . 22(33) 2)(29) 28(29) ; total 6R 68 85 hR 85 M5 68 123- 65- - 67 ' 1 67 i . 73 ~ . 97, 70 reds - - 39(45) 37(46) 37(48) L40(51) $3(49) 32(44) S 39(45) ? 31(41) 32(43) 46(44) brwas . . - 26(30) 2N29)' 22(29) 20G6)' 2R(26) 22(30) 26(30) 25(33) 21(28y 31(M)- greeta . - - total 22G5) 20G5) 18(23 L 18(23) !??(25) 19G6) 21G4) 19(25): 21(28) 28(27)' 87 80- 77 78 : 100 ~ 73 / 86 - ' : 75 .. 74 : 105 WP reds 33(45) 34(47) 45(46) 42(44) 39(43) 43(48) 41(47)l $8(46) 36(44)-34(45)~ 40(46).32(42) 47(44) humus 18(25) 20(24)-25(26)-24(25) 23(26) 22(24) 21G6) 33G6)- 20G5)" 16(2I) . 21(24) ; 20(26) 24G3) greem 22(30) 24(29) 27(28) 29(31) 28(31) 25G8) 23(26) 36G8) 25(31) s 25(33) 26(30).'24(32);35(33) total 73 fi3 97 95 : 90 90 87 -127 - 81. 75 ' ~ 57 76 . '.106 Total reds 45(45) 4R(46) 60(47) $8(44) 57(46) 60(45) $3(46)L 72(46)' 54(45)" 59(48) .$9(49) $6(47) 6R(48)E brtmas 26(25) 26(25) 35(27) 35(27) 32(25) 34(26) 29(25) 40(25).31(26) 30(25) 30(24). 32G6)' 35(25) greens 30(30) 30(29) 34(26) 3R(29) 37G9) ' 38(29)' 34(29) .- 45(29) 35(29). 33(27) 34(28)233G7) 3R(27) total 101 104 129 131 126 132 116 157- 120 .122 123 121 L 141 1 Rocky Intertidal Studies 1 195-
,~ . . .. - -. . __ - , ~ _ . _. ._ , -
,i i
- l thee populations established themselves, ~ %c our studies, indicating floristic stability in .the l
persistence of these species suggeHs that present -- Millstone area, which_is consistent with that of ! conditions at IT may be selecting k>r more waren. - other noristic studies in New England (Vadas et l water toleract strains; other researcher 6 have - al.1976; Wilce el al.1978; Schneider et al.1979; =! shown a great deal of intra specific variat flity in Mathioson et ali 1981a,1981b); Change . in - l
. proportkms that occurred in the effluent quarry:
. environmental imponse (Mathieson and Prince. 1973; Stromgren 1981). at different reactor power levels (Schneider 1981; NUSCO 1987) reflect elevated temperatures, and he appearance and persistence of Sarpassum j provide additional reference for' future studies. fdi adula and Gracilaria r&veMaciis further Specifically, a , thermally y stressed a flora : is , characterised by a reduced number of species, nec for as new .envitonmental domain. (Bradbury et al.1984) at FE maintained, in part, with a disproportionately.large decrease inlthe j( by 3. unit operation. ' Both species were first number of browns For cammple, only 97_ misal _} collected at FE in August 1988, and subsequently, species have been collected in the MNPS cffluent 1 Grac# aria has, been ' present in 50%, and_ quarry since 1979; proportionally 48% reds,13% i
]
Sargassum in 100%. of all FE collections. browns, and 39% greens. ! Although these perennial species are not new to-Connecticut (Schneider et alc 1979), they are Cluster analy61s techniques welc applied to the - more typical of sub tropical waters (Taylor 1957) qualitative algal data this year for the first time, or warm, semi enck> Sed bays in our area (NUSCO - ; he hierarchical dendrogram (Fig. 3) reveals three ' , 19N9). The persistence of these species al FE - distinct groupings at the 30% similarity level. Indicates that conditions during 3. unit operation Group I represents all annual collections made at-are toictable for thesc species. This could allow . WP, MP, ON, FS, all milections from BP except for the further development of a flora which is. 1979,' and annual collections made at FE from > d resilient to, or at least tolcrant of, the range of - 19791983. ' Oroup ' 11' consists of 'all annual j water temperatures resulting from present - colicctions at *fT, SE,1 SS.' and . one annual 1 operating conditions. ' It remains ,to be seen collection at BP -(1979). L Differences between <! whether future scheduled and unscheduled unit these groups are primarily attributed to the type . j outages will cause perturbations outside this range of algae that. grow on thcldifferent substrata : '! and result in a further alteration of the present- _ characteristic of each group of stations. Sites in flora or whether the flora that presently exists at Group 1 are characterized by ledge outcroppings; ll FE will temain characteristic of this site. Oroup 11 siter, are composed of boulders and j cobble. Group til is distinctly separated from the - : The flora of the Millstone arca was partitioned first two groups and is made up .of FE'annent ij into number of species in cach algal division- . colicctions from119841988 , %is separatkm (Rhodophyta reds. Phacophyta browns, :and- cicarly lilustrates'the power plant induced floral' l Chlorophyta.grecas). The species numbers of changes lhat have occurred at 1FE .since' the; .) icds,- browns and greens' were" scaled as iopeningo of the second? cut, Ink gencial, : 'l percentages, and thcoc dMsional proportions er - throughout cach group, stations are most similar J l ratios were used to characterize subsets of the . to themselves over time, These data suggest that j overall flora at cach site and throughout the area the floral composition at)NUSCO study sites, j during various periods. For cxampic, of the 121' exclu' ling FE have foot changed noticeably'since l species collected in 1989, the proportions of red,- 1979c brown. and green algac _(as percentage of : 'al number of species) were 47, 26, ; and 47% i respectively (Table 2); Corresponding proportions ; l 3 . for L2 unit, years 1 were L 46; = 25 " and - 29%,1 ai respectively, and for 3 unit years _ to date were 48,1 _
,i 25, and 27% Proportions for the overall flora IV L (aut case); Clauenns deadavram or specimi =j
, ;since 1979 (l$9 species) were 47% reds,l 2$% similaruy, ty station and year (197919as). for qualitative algal' 'i i browns, and 28% greens. Proportions have been j
. similar at each station, in each year throughout ij l
;196 Monitoring Studies,1989 j
- 1
;{
.- _, . . _ , _ _ ,_ a. ,
= -=- -
t'E l . g-g, p . . -
g g 4 . n * ' i "
,, , i ..
._r'.y ~
q y ",J. 5 { /.[' 7
" 7 9 4-
.1 f -; ' l'
.I i .?
? q .. > ,O; t '
' ~
-t 1
4
,p' ,
_' t f'. g I,\.,1'
.' { .:- ,; , 2 (,;
'2- P- e g :.
- g R $ -- ' $ .; .$r - R; $ ' c ' $5 , . -
- j. '. l . .. - - -
- o i- .i . i .6 ~i ' ' ' -
y l .
, w -
, 1: .y:
/ l .
,t'f , K Y
, m. ;-
g *
, 8 ,
; 4 yk 'l i d- s i
, y .t.
!, 4 q
F e i < <-I 3 + a j r ,' t i s j r - y 1 W q , *
,N.6 (PJ .k < [
4N' ..i.. ,
- g. g1 .
-g ^ d [S L
.r
- '[
+ I -.
f x i f
- 1 4 P- . 3 i ;'
Li c 4j - 4 ", - - 6
- ' R<J J: , }\
- 40. 6 p.. . -
1 E. b ._
- s. -
. - a P4 8
- j. 4 i i S!
4
'. .m , 2d ,
i f( I i - i d' .. 4 :. e g -i %, ., n p
+ r .
s I 1
~ _ , .
1
)
r e-g g L.4 s < .1 l' , ->
=,i, [ '.
2 . - ; . g. . s , M {:. . . 2 ,{' .
% 3
= '
_,,.q c_ i C > j
<. (
v ,.-. j
- h. ..l- .k >) .0:. 3, d ', 'h , j-- ,h . ,* ' l E. il.' +
' 2'
- 2,.
R R,.'t-. >2- l- 8 ' 'Rl M- 8 :: t
.B: m^
R .-- A;poipuis sensa .
~-
+ , 1- 1
%W Rocky Intertidal Studies f19N y 7 ,
kcj~ ' y 1 T 5 y
,j'-_',
"b.
r -
,,p , ~ , f} }
.,' ' pj L -'- .n .1 ed *
^
, < ., <g.y 3 '. '"
(( ! Y. - , 3
, ) (.. y%.
n
~fy.r 89 ,
i 8 r Q^ j":' ' 7 .
.{(
~f^
- 3; i" N.:* 97 - -
g^- <
- L',
~ i_ [Y ' l ~ .
- .. - ~
e- --- - . -
, -1
^
Abundance Measurement. scason to season, but its annual occurrence cycle j is highly predictabic. Patterns of abundance over . -t time for local barnacic populatkms are illustrated 1 Rocky shores in the vicinity of MNPS support a large number of ' plants and animals that, in Figure 4. During 1989, maximum barnacic coverage in Lme 2 ranged from 30% at FE to collectively,, comprisc the local rocky shore cominualties. Relationships of these species to _ physical factors (e.g., wave-exposure, desiccation, 80% at BP. Except at FE, abundance values in 1989 were typical of thme seen since Unit 3 began operation, and similar to values tcrorted j ; water temperature) and to each other =(c.g., inter, and intraspecific competition, grazing, predation, during 2 unit operation. ~ Throughout the rocky j epiphytiantkm) create a complex mosaic whose intertidal monitoring program,- - patterns. of 3 appearance changes from station to station, abundance of kical barnacic populations have 1 acason to season, and year to year (Paine and clo ely resembled those reported for the species l IJvin 1981; Sousa 1984). > An understanding of by other researchers (Connell 1961; Menge 1976). l this : . dynamic equilibrium (DcAngelis :and Typical developmental sequences'are described - j Waterhounc 1987) is aided by analysis of' data below. 3 from species and community , studies in '! undisturbed tranwcts at nearby rocky shore Barnacic cyprids settic on rock su faces in late = l winter- (Feb.. Mar.), and quickly metamorphose j sampling sites.- into' juveniles. Coverage of these organisms j Undisturbed transects are permanensly marked, increases during. spring and summer 'as thesc ! repetitively sampled (six times per year) areas at , individuals giow, and reaches a maximum of up . .j cach rocky shorc station, selected to -be to 85% cover of mid intertidal surfaces in June or repicaentative of the topography,. degree of . July (Fig. 4).c High intertidal (Zonc 1) and low-exposure, and blota of the adjacent shore areas, intenidal (Z4mc 3) maxima also occur in early t The abundance of attached plants and animals in summer, but cover values are lowcrt 5 60% in i undisturbed transccis,dctermined as percentage of Z4mc 1, and 20 50% in Zone 3. Cover in Zone .i substratum coverage,is taken as representative of- 1 appears to be related to the extent of the spray !
- species abundance in kical communitics. Changes rone, and is greater at exposed stations (e.g., BP, . "j and patictns of abundance that occur over time in FE) than at sheltered sites (c.g;, FS, ON).
the transects - represent development of : the community at that site. These pstictns of . Balanus cmerage is reduced L in all tones abundance for important components of local .through latc- summer, autumn, and winter, as rocky shore communitics arc descrital below, barnacles are removed by a variety of biotic and j
- abiotic mechanisma. For instance, barnacles may
- Samuelcs : be killed by desiccationhtarvation (especially in d the high intertidal, Grant 1977;;Wethey 1983), ']
The most common barnacle on rocky shores in crowding 3 or - hummocking'lintraepecific j the MNPS arca is Balanus balano4/ct, although competition for space t(especially inc theimkl . l r.cveral other species are common subtidally, and intertidal, Orant 1977; Dettness 1989), at inter. I may even occur intertidally in smaller populations. specific competition ; (e.g.i twitt,i mussels) or - Some rescarchers refer B. balanoides to the genus predation ~(Menge 1976; Katz 1985; Hughes and Griffiths 1988). The I.atter two mechanisms are ;j
- . Semihalanus -(cf. Exposure Panel section of this .
report), but for purposes of this program, m a imgortant in Zone 3. where mussels and ;
' barnacles' and 'Balarma' are used interchangeably intertidal predators are most numerotts. In the to refer to the northern rock barnacle. MNPS arca, the carnivorous snails 1 Urosnipim ,
cinera and Thais (mNucclia)lapillus arc the most ; ;l Barnacles occur : locally throughout the I'"lmnant predators of intertidal barnacles. Thesc . j intertidal' mone, and extend into1 the ' shallow snails are most active and abundant in summer? ! subtidal, 'but they predominate in the mid- - (Fig. 4); although they seldom exceed maximum :l
-+ . intertidal (Zone 2), frequently under a fuccid e cmcr of 13%, they,are a significant sourec of; q
- canopy. , Barnacle abundance varies greatly from. - nortality to low intertidal barnacles and : may. I cffectively climinate Balanus from Zone 3. l
-198 ' Moniloting St'udies,1989 l ei
.j
, o
. .a v a s etvi-e ',*' s.~ 4=
- r.4 m vait 3 eiri-up
.o ow I F i-W ;p .:
y-N \;h .bsl\. k((Yj ,k Q... } %h } _l j'L. L u' ^
- I .
Y'Y I'f[t*5.I"#,I".3 Y". I ~3! Eo.'1"a",'.4t#. " Y'E UNI'5I"E IM'*5 U Io.~1D'f.48f Y"E ' '
. . . . vo4 3.i-t-vo a. u.. . c. ..a units iet-up
. =
}
s {" I [d t l i I fo s.
. ". .g ,g i <j 5 s. ( os 't
^
n> fa
' ' ?
\
! l .
*d M' 'sC,b"ji?. M h? Yg,)R,) Q g W TrP.% Ci G #,M 7# U Cjt_%f,,M ra l
- e. a.. . *,m unit 3 iwi-oc = a..,......, ,m
, u a s wi-up i
. =
. u.
I g h *- t h y l11 i l\
,1 ,A h,
- f' i
' ' u.
% > ) 4}s\ l' l' ' i
's i
\
;&lk 'Df
\
\ 'I b hp i '0;n Ndv ill\lh'h.bubba)\
2e ne vef ne.v.a: r. ur,,ve . , n.e..r.t.#,. va J- %,v.e v. ve r., t-M.u..J U.r,
.u. v_., %- v.c ve vai
- a..w * .~*, . . . . . ~ . un t nici-ut,
-e..,r. . una 3.iwi-w 5:-
30
'".4e.
5s ief, 4
. ~ ,A j' .
g v. N in r- I i , - Ei . \ b,]3]UYl!r~vif[l\h!'hfi [I . .)h, e.h
\
~
~
, ., 7 7 (y b ' I -
!\ je{
i\ ?) l\ 'h. klI,\ > i
. \A 6, I' .i ,ty..s . vg[,{% L
[fL'L()atj)/,yl,<Ob 3 \/ ~ , e ,, g-t
. .Y .
a._.. Y
.8 ' b. ,^_,/t n g Ya v.? t %7 %Y:va u,r.o.v1 -
%%.Y Y.#. 72 Y ~
?.7 %% IYM %Y %~% .a- - .va -ev1e %?.At"~. 7.C ,
Fig. 1989.
- 4. Abundance of flalarius in each sone, and of predatory snails in 7.one 3, of undisturbed trannects, from March 1979 September; Rocky intertidal Studies 199
I Barnacles may aim be lou during 19119) is now evident in 2 me 2 at FE. _his autumnAwinter storms; as overgrowth of - decline appears to be related to competition for inacroalgae in detached, underlying barnacles are space resulting from the skvekipment of a denne removed Regardles6 of the mechanism of kms, mid intertidal , Fucus ; canopy, which will be rainimum values for cover occur in late wintet described in the next f.ection. (typically 10 40% in 24mc 2), providing free space for settlement and growth of a new barnacic Fucus generation, and repetition of the annual cycle. Fucus wskulosus. isD a perennial brown Consistency of the annual cycles of Balanus macroalga that has been a umaistent component abundance at most stations in the Millstone area of local rocky shore communitics throughout the is ' an indicatkm of_the predictability 1 of MNPg rocky shore sampling program. Other tasa - environmental- conditions, and of the local of Fucus occur ; locally - (F, . distichus. L sutsp. intertidal communley. In contrati the sharp connescens, F: distkhus sutmp, edentatus, mostly.. discontinuities in patterns at FE (Fig. 4) renect subsidally, ud F, spirolis, mostly high intertidally), altered environmental conditions resulting from however, F, vesicukuus is the taxon referred to by' the second quarry cut opening (August 19k3), and the generi;-term 'FuruA as. It is clearly. the to a laser extent, operation of Unit 3 (April dominant lucold and the most abundant alga in 19146), Changes to the e,hore comrsunity near the the mid4ntertidal mnc' at malcrately empmed? MNPS discharge, sutsequent to the opening of rocky share stations in the Millstone area. Fucus the second cut, have been described extensively in ' abundance is limited at highly exposed stations by past reports (e.g., NUSCO 196t5,19616,191t7), physimi urns (l.c., wave shock), and at sheltered This report emphasir.cs community development sites,~ this species is typically outcompeted for since Unit 3 began operation.
. spaco by Ascaphyllum newfosum (Shonheck and-
%c shore community at Fox Island Expmed (FE) continues to be affected by the thermal Trends in Fucus abundance during 1989 were plume resulting from 3. unit operation. As-reported carlict, this plume is denected cauward consistent with those previously reported (Fig. 5).
Maximum Zone 2 Fucus cover at BP was 2%; the - (towards FE) by the cbbing tide, and westward by the nooding tide. . Consequently, water nigh> degrec , of cupmure and Hecply sloping > temperatures near FE are cicvated for most of intertidal substrata ; continue - to l preclude cach tidal cycic, but decreanc to ambient levels for : development of a Fucus; canopy in_ the 2 3 hours cach (yle near the time of high tide, : undiuurbed transects At WP, the relatively kiw; Derefore, organisms in the upper intertidal areas abundance of Fucus (10%) renecir the -large - at FE are not expmed to - clevated . water number. of mid intertidal' quadrats covered by
. Asmphyllum, Maximum Furus cowr ht MP. in temperalmvs. His community is submetscd only- 19019 was 17%; trends at this station are discuss near high tido and cxperiences only ambient .
. ed below, At all other statkms manimum rnld temperature watet, Parther down the tidal rpge, plants and animals are immctsed in heated water . imMal Fucus amt w hem 4 ud M', :
for a proportionally long:t: time. Tbc kiwest portkms of the intertidal sone - at FE are At M Mh an annual cycle of Fucus-wb}ceted to cicvated. water temperatures for 9 abundance is apparent in Zone 2,j This fucold: 10 hours cach tidal cycle, Effects of - this annual cycle is similar to the annual periodicity tidailthermal regime (3. unit operating condithms) - 1,oen for barnacics. Fucus permlings were first? on barnacic populations in each rone at. FE prmnt4in ~ early summer . frequently: in ; the)
.during 3. unit operation .are seen _in Figure 4,'? interstices between barnacles, with . increases.in utarnacle survival (as percent cover) was lowest - populatkm and cover apparent into late summer, j (0%) in Zone 3 and highest (15 25%) in Zonc 1, Maximum cover varied greatly among statkms; 4c,,,, <2% 'at BP4 >75% at FE and FS)cl Fucus Survival in 2nne 2 was intermediate (215%). A cover decreased, in; autumn at i cach . station. -
doctine of maximutn annual barnacic ctwer since
=
Unit 3 began operation (78% in 19116 to 32%in - through a variety of mechanisms. Plants may bc 200- Monitorin'g Studies,19119 _ _
.-.. u,0 .. .,, . . m . , .., veo .,,,i,,
94 Of 96 to i ao.,
; . )M y* e-
,, so
' g om }'
}
+
v,e v.:..w e. ra .w..,r,_ .w, w _ .,w _ . v,.s.,..v. c v v. v..c. ..eiv ._a.a .te. , v.x. w.- ve
.. _ . .w
. v..c w
% 4 r .m or. i 3 atet. up w ar=.m unit 3 sirt-vp
- .-. ',Q
%. s sk l M d f. & d y
- i mm j\n\\\ . 3b /
-' t, "
\l
; 1 y *-
( n. .s i a Si ' n,dy ( j qi, y se
,$ . , b lNV\/, 1 rA,fg
, ',Ql, e* N' y '.rp(,- _ j-' lsinf I, l'4 I
,7% h,,Hi\ fi,.,
l 4
' ' si h *b.MLt j lA A/ f.d.'d,d,.\ A
{? /a
- t. 5
, s %.k_.
*\ '.' %C..*n;.# *;,_E w %,.Y %_?. *,*%. 3T E .*. W.u m*; & % # Y YA Yd'.%. *1 a.%%.2Ya. - wie is a Y2
- 'e'N nn YZ 72 '
ei.... .,....
",'; r e
4 , .... un.i 3 sirt.oo
'{
- w. .
sv a r..,m umt 3 stet-up 4 4
. a.
A , u Yw f\+ (e , {$.u, t y[( e/ u,,q/'\ \/,, L f,,b/ 't #\
~
'a
'6 "s J (c' \s e FWgV'\PNj\p,u,f4 i ! g Q / J g. q qs. % G>
w =;e r a e w e s.:- w - ww:wasvwar-te i . . . . , . . r ue a e n= pt 3 start-up *' rwcw a p .m Unit 3 start-up Pn 7% y as. M ye d g e. r, ww k D,,T w
- ses,,y; y y;3, 7.,
w . , 5.' ' w gw,imjg;,,;m ww-wm fl.li k w ,i o =,,.. kf w hg 5. Abundance of l'ucui in each rune, and of grutng snails hi ame 3. of undisturbed transects, imm March 1979 Septemtvr 1989.
==w kfV w = wy; ion y;g in., g ,ieg;,,pu im Rocky intertidal Studies 201 I ii u ..
i lost through senescence, as F. resiculosus has an However, if these processes occur on a larger ; ccological life span of 3.$ years in the Millstonc spatial kcale, the annual cycle may be ! arca. As individuals age, they become more superimposed on a longer term cycle, based on ! suweptible to epiphyttration and abrasion, the life history, longevity and age structure of j increased drag removes- portions of plants, or fucus at a station. For instance, if a large arca ; entire plants, resulting in dc<rcased cover (cf.. of rock surface is cleared of Fucus, e.g., by a , Menge 1975). . Plants may also bc lost if they are severe storm or ice scour, the germlings that j inadequately attached to rock substratum;if &cus recolontre will necessarily be of the same age. .! settles on or among barnacles, and the barnacles When young, these plants will be less likely to bc + arc sthp,rntly removed (e.g. via any of the epiphytlyed and removed by storms; as they grow, , mechanisne proposed in the last section), the percent coverage increaser. _ However, after plants would be removed as well. All thew several years (3.$ in our area), large individuals , promes have been observed in the present become more susceptible to temoval; as they are - '
. study, lost, percent cover dcctcaws. This type of long- ,
term cycle has been seen at FS and ON, ; licrbivory, or grazing, is another potenti;.1 source of mortality for Fucus, but this mechanism A similar cycle, noted ht FE, was interrupted l has not been important in our Study. Adult by the opening of the second quarry. cut, which Fucus has both structural (tough cortical layers) . resulted in complete Tucus mortality in i and chemical (phenolic compounds; Ocisciman September 1984 and September 198$. Operation , and McQmncil 1981) defenses against damage of Unli 3, and the associated 3. unit discharge ; from local -herbivores. Newly settled Furus plurne, has permitted recovery of Fucus - sporclings are vulnerable to grazing, but exhibit populations in the mid and upper intertidal tones , temporal and spatial escapes; i.te, settlement to pre-1983 levels, but Zone 3 continues to bc : occurs when herbhurcs are relatively inactive, and exposed to conditions unsultable for survival of j' rygospores that settic in lock crevices, or Fucus (cf. previous wetion). intersticos between barnacles cannot be reached ' : by local grazers -(Lubchenco 1980, 1983). Tucus cover in 1989 at MP in Zone 2 Liturina hrusca is the dominant intertidal (maximum 17%; Fig. 5) was the highest reported herbivore on rocky shores in the Millstone area. at this site since 1983. As tcported previously, ; Other littorines (L obtusata, L datarlhs), other there had been a general decline in Turus j gastro[uls (Lacuna vincia, Acmcara restudinalis), abundance at MP, from a high of 43% cover in - l' amphipods, isopods, polychactes (mesograzers September 1982 to less than 1% in March 1986; L sensu llay et al. 1987), fish and crabs all and a subseqacnt increase .to the present. l Omtinued monitoring will allow us to determinc contribute to graring pressure to an unquantified, } but lesser, extent. This paring pressure has been whether this increase represents a protracted cycle shown to be important to the structure and nf Fucus abundance, development of local rocky shore communitics, l L but has t!!tle direci effect on the annual tycle of Chondmf Furus abundance, , Chondms crispus is a cartilaginous, bushy, If the processes that increase Furus ersiculosus perennial red maroalga, common on stable rocky percent cover (recruitment, growth) are bal.mced, substrata in low intertidal and shallow subtidal 4 on an annual station wide basis, by those that areas throughout the North Atlantic (Mathicson 1 l doctease it (senescence, death), the mean annual pod Prince 1973). Despite extreme morphological - abundann remains stable from year to year, e.g., variability, C. crispus is the only species of the
' at SE ' SS, and WP (Fig. $). Since Tucus genus recorded from the North Atlantic, and in. I' l- .
- perennales (l.c., individuals live for severn! years), this report, Chondrus refers exclusively 'to C,
, the annual perkidicity of abundance at these sites , crispus. On the cast coast of North America, . ! implies that the processes of growth and removal Chondms ls found from New Jersey to Labrador ! , occur in patches that are small relative to the (Taylor 1957) and locally it is the dominant alga . l- total arca sampled by the undisturbed transects. 1 202: Monitoring Studies,1989 j I i. i q
. _ . _~
\.,
y
. .,... ..o .. . . .: ~ ~ . . ... - , , , _ .
,,v1
^{. \!.
.. \l.%j
\ ,,
-l :4!n, y
.~i,.@ g /vy; y l" "fj v\l t , .I:. - .
, 'y; i .
l+ t\ ,\[(Q;' 1 ,. . . . 1
, !]Q !\,\;
4 w v.c. o. 17
.- r n.4.a,.
%.e -.
.- e vP4. %v.r ,v e -
v.c.r, if.e e. w w v A.mi. v e v.Te,%. e.v., r r . m _ _ . . ~3.,,,.. - _ _ . . _ , . . . o o ..... 4 4 v
, jA,,e[
g0 44 g: p1 1 wg .J. jy gl .,' .: . '
- o,4,.3yj..qa.+ q.
; 3
[\ l , , r 1 V f 4; e, . t : - i ,; g,.a l ~ 3h; ,'i'\;W,;\ -\i ; d
': \ if,, !'\ \ n is !
!\ .. ft, h h ,b, c
- M; uJaJJ l
<- vJ, u,h, rs Uu a i u=unrxanaczw*
uwnraxxocauxw ...... i: -_ _..
~ , . .
.: ... o ,o ,,_ . - .. o o .. ,4.
30
.,e to lo -
to- a g
, ,! .sf .; /\ -
kN j'"YlV,.yAes[\/\[* ',T" ' ,/Vy /gf' 4 .
.lb,l%!\exAh b "
j ;- Y(. l Fr
% 7. %. I, %a.?,.- 7 7 % ? ? '* % P. ?.P ,.i. %?***%P %7' W P..#. .. "U,.?
. %7 %b.v?.m%. PX? %Y*d.e.n.T., %7
....o~ -.4...,
'* c *
. er 4e.. twt 3 ata t.e oi.an%. a .s.<,4t..
unit 3 ewt.-6p u o
.?
j
# k' M // '
I k kg ly!' I V V
'w \l ';fq p
f ["v[ j ' lpV) j\i] se a 1- , g= g p i io. p . h .h YI\ , ,I ' f\ f
.s ..
I's t. , ' !'Yb,I,
\,
YsY YE1%? %Y %Y %? Ys Y.P'M' %. ?.%Y %Y ,
. .m 1s,. s ...az _. m>u.a s.e,. ,, m. #.e,.t.> a., u. m.-
Fig 6 Abundance of Ouvidine and snajor epiphytes in 7ene 3 of undisturbed trannects, from March 1979 September 1989.: Nocky Intertidal Studies L .20,i
1 i t I t of the low intertidal rocky shore community (Fig. comparisons among stations' and among years. l 6). Patterns of Chcmdms crispus distribution - Memostroma spp. (mostly M. pulchnem, some M. l during 1989 were c(msistent with those cited in grrvillri)- are thin, sheet like _ green algac,; t past reports (e.g., NUSCO 1989). Cover in Zone characteristically found in spring collections (Fig. '( 3 averaged between 35 and 70% at all stations 6. Table _1). Maximum cover values at most . except PS and FE.1.nw values at FS (8%) were- stations are typically 510%; low values at FS (1.- attributed 'to unsultable substrata, as Chondms ~ 2%) are related to limited Chondnes abundance at - , sporcs do not settic well on silt-covered surfaces that . statlon.. 'Monostr<vna . has ' been l most found at this station. Imw percentage cover - abundant at SE, occasionally almost 60% cover - values at FE (<1%) were similar to. those . - (e.g., May 1989). _ Values at FE were high (20- . reported last year for Chondnes at this station, but 40%) prior to the opening of the second quarry J CNmdms abundance at- FE 'during 3 unit cut, but subsequently,M<mostroma coverage at FE- 'lf operation continues to be far below the levcis has never exceeded 1%- seen prior to the opening of the second quarry cut, when average cover was >$0% Polys /phonin sppi(mostly P. norac angliac and - f P. hancyi) are also common epiphytes on . ~1
%c continued low level of Chondnes Chondms, but may grow on rock or on almost i abundance at FE is evidence of _ unsuitable - any macroalga in low intertidal areas. Patterns of~ ,t
- environmental conditions for - this species, abundance for Polystphrmin show ranges similar to Chrman4s is restricted to Lme 3, where it is those of Memostroma, but are temporally shifted;-
expwed to elevated water temperatures for 910 maxima occur in late summer. autumn (Fig. 6). hours during each tidal cycle, unlike the Balanus ' At FR, the typical scar,onal pattern (l.c., high in } and Tucus populations, which extend into mid and autumn, low in spring) was apparent prior to the j upper intertidal'arcas. In addition to thermal .
' opening of the second. cut,. but the tycle was - i stress, Chondnes competes for space with more. subsequently interrupted; A$siphonia cover at. !
thermally tolerant species, especially codium - FE cxceeded $5% in November 1983, and has> l fragi/c. Codium exhibits rapid growth, and has an since remained relatively high. The persistente of : cxtensive filamentous basal system that' traps j! the A>lysiphonia . population,: particularly ' that sediment; both characteristics inhibit settlement portion of the population growing on rock, is; ; and growth of Chondn4s. In fact, the low. attributed both to. clevated water temperatures '; intertidal community at FE,_ dominated by
~
and especially, to the virtual absence of grar.ings Chondms prior to 1984,is preacntly populated by - snails at this station since September 1984 (Fig.' .,
)
~
Codium, Uha lacruca. Enteromorpha spp., and 5). A$siphonIn spp. .
%c year to year consistency .In patterns of -
In contrast to the ressmsc of Ch<mdn4s to the abundance of Chondnes and its major epiphytes in- j alteration of conditions at FE, the consistent the undisturbed ! transects _at the rocky shorcE q abundance of Chondms at other stations is - stations (excepting FE) is additional cvidence of-- j evidence of stability of environmental conditions the stability of environmental conditions in the; ; in the low intertidal community, throughout most MNPS area. Conversely, the perturbation of the j of the MNpS arca during both 2 unit and 3 unit Chondnes association near the discharges (FE) is <l operation. Stability is also seen in the regularity .a clear response to the alteration of conditions '; of seasonal- patterns in rebundance of major that began with the opening of the second quarry ~ j cpiphytes of Chondn4t. cut, and continues to the. picsent. j Many local algal species can grow epiphytically; Similarily Dendrograms. 1 some are restricted to a particular host, others 1
.can attach to a wide variety of substrata. *fwo Rocky shore communities in the Millstone area !
genera' arc of particular interest, since their arc _ very complex; over1125 taxa have been - d abundance, wide spread distribution, ;and . identified' in mid- and low intertidal' rones of - l [predictabic ? . patterns of occurrence permit undisturbed transcets since 1979. Considerable: 1 .. O I l_ l204 Monitoring Studies,1989 u ; i 1 L ; L -t j i
,sa - ._ u _ , _ _. _. _a
attention has been placed on a few dominant subdivision of Group I is attributed to high Furus species (e.g., Fucus, Chondnes, Balames), or species cover in 1979 and 1980, and declining values from that, due to their feeding activitics, influence 1981-83 (cf. Fig. 5). The subdivision of Group !!! distribution and abundance of these dominant is attributed to further community development species (e.g., Littorina littorra, Urosalpint einerca). since Unit 3 began operation, e.g., the appearance However, the first appearance of community stress and persistence of Sargassum, Gracilaria, and may be changes in abundance of those species Chondnes. The highest degree of similarity among which are found only occasionallp Therefore, years at FE occurred between 1987 and 1988, assessment of sitess may require cornmunity indicating the smallest year to year change, and descriptors that include abundances of more than supporting conclusions drawn in previous $cctions. the numerically dominant species. The liray. Narnely, the present community at FE, although Curtis similarity index is a technique of different from the community that existed prior to comparison that uses abundances of all species the opening of the second cut, exhibits a sampled. A clustering dendrogram illustrates comparable level of similarity among recent years, multiple pair wise comparisons. The classified units are composed of combined annual The above analyses of data from the local collections at each station for 2. unit and 3. unit rocky intertidal community, as represented in the operational periods. To characteria the undisturbed transects, are primarily descriptive. community changes at FE, annual collections in the following section, we will discuss ami from this site are also analyzed separately, quantify an important process responsible for producing the observed community structure, i.e., Relationships among stations during each recolonintion of intertidal rock surfaces. operational period are illustrated in Figure 7a. The highest degrees of similarity are seen between Recolonization Studics operational periods at each station, i.e., 2. unit collections at each station except FE are at least Creation and repopulation of patches of bare 80% similar to 3. unit collections at the same rock are important processes to local rocky shore station. At the 60% similarity level, jour communities. Continuing availability of substrata groupings are apparent: stations in Group I are provides opportunity for settlement of benthic characteriicd by moderate amounts of focus and speeles, and permits year to year consistency in Chondms, those in Group 11 have abundant patterns of species abundance noted in previous Chondms but relatively lhtte Fucus. Group 111 sections. Periodic disturbance, or removal of (FS) has high Fucus cover, but little Chondms, biomass, maintains local species diversity and and Group IV (FE, 3. unit operation) is prevents monopolintion of substratum by a single characterited by high coverage of Codium, Uka, competitive dominant (Lubchenco 1978, Dethier Pohsiphonia, and Enteromorpha. 1984). Recolontration of naturally occurring patches is commonplace in our undisturbed De high degree of dissimilarity between the transects (cf. previous sections), llowever, more comnwnity m FE during 3.umt operation and any extensive recolonization studies are included in other station! operational period is apparent in the rocky intertidal monitoring program. These Figure 7a. Ilowever, community changes studies were instituted in 1979, for several responsible for the separation of FE did not reasons. First,it was assumed that the responses begin with Unit 3 start up, rather, the changes of newly settled and juvenile stages of intertidal were associated with the opening of the second organisms to changes in environmental conditions - quarry cut (August 1983). While resulting would be more apparent than those of adults in community changes have been discussed in detail established populations. Second, by removing all in previous reports (e.g., NUSCO 1985), changes biota from the recolonization transects at the in community similaritics are illustrated in Figure beginning of the experiment, we climinated the 7b. Three groupings are dpparent at the 50% variability associated with a variabic age structure. similarity level: annual collections prior to the Finally,if rocky intertidal recolonization were to noted changes (1979-83), a transition year (1984), and subsequent annual collections (1985 88). The Rocky intertidal Studies 205
0* -0' 10 .' 20 - 20 30 - - 30 40 , 40 i so . -. . so . t 60 I '
!!c I} \ ,. }Y + 60 a
1 70 -
- 70 -
30 . Do 90 - . 90 .
#p J $+ $J $+ %J - 19+ J $+ %
4
+
a. 4,
- p. '4a.4-+. 't a
p, --- #cJ
- ligwe 7a. Omtering dendrogram of timilarity, by station and operating period (2-unit and 3.unN). - .
=
^
0- .o 10 - . to-
, i.
20 :. 20-30 - 30 g 40 -
. 40 A. . -
- ~
d so -- 1;. ))- -ijj ' w so l'so_- g . so ,- la ib' 'lila 111b - ..
. ;to 80 J . go.
i so .s .
. so
. lI:)- ....
s - + 9 '3 . -
?
D ^ _ 'S l$ , f& .. Pisweyb. omentag dendrogram or seminertiy, by yar, si ra hiand.nipand
. y -+-
W 206; - Monitoring Studies,1999 y n -_1, ( , ,. '..$,' 3
. -' .I l J
\ ~
1 & follow a classic successional sequence. (sensu eviuma *a"* evioma- ~ Cicments 1936), from pioneer to. transition. to [ NUe EUo, - climax species, pmsible power plant impacts on a , particular stage of developmental of a s
' ^ >
recolonizing _ organism could affect the eventual' h .,, '
\ .
final community structure. 1* , [~ ,( During both - 2 unit and 13. unit _. operational- *
\
f , perkxis, tecovery of high intertidal communitics " y _
,"/*
after autumn denudings was tapid (<6 months) at j -y b '. - o all stations. *fhcre is littic biomass in Zonc 1 in == = ^=_= ***** ~ *"""'*'
= = =+ = =
autumn, tnd scraping and burning of essentially .; bare rock surfaces docs' not appreciably aller their evevma "au. evioma
- appearance. By the end of the first barnacle set ,,
Eba, E es, ' , ' (l.c., April 1982 and April 1987), high intertidal ,, recolonization quadrats were indistinguishable -- k ,j t c 1 , - from undisturbed areas nearby. There werc no k = - h. i{' / p, "; l-differences in rate of recolonization of Zonc 1 between 2. unit and 3 unit l periods, and no g'* %', >I -- V ' [. -a* a observed differences among stations (NUSCO 1989).
* . (d '
I,)
~
L - Mid intertidel Zone 2 communitics' arc =+ == == =*a == == ==**a-structurally more complex than those of Zonc 1, ~ ** *" * > ~ '"' * "'" ~ and recovery of these communitics on denuded evioma '"*-a= eviumnn substrata is a more protracted process. -locally, EUn, - ' UUo, mid intertidal areas at the recoloninition stations ,,
- ate dominated by Balanus 1 and _ Fucus.
Recolontration in Zone 2 is assessed in terms of {: . c? (O [ recovery of populations of these species, relative 5 = $ lo their abundance in undisturbed areas. The l (a 3
\ _h/ : "e
,l ..
~~4
. rate at which these populations develop is related
- to a variety of factors, including the slope of k' f ~ l$'
v substrata an J degree of exposure (both affcci the - 'f 3, ' [ amount and duration of available moisture), the um um um =+ == ==~a n * ==7 time of year in wh!ch denuding occurs (which ~~**"""*""'*' aIIcets the type and quantity of sporcs, rygotes, eveemn en or-eviemn lamic. etc. available for settlement), and natural . '") nun, ; Mo%, .." a variability in rates of recruitment and growth of , m - such propagules. The effects of these factors on - rates and patterns of recolontration following the k c .,, -L: , autumn 1986 denuding (3 unit operation) are 5 w ' f' - l .,
-described below,
[* =j F Barn icles : r,ettled - densely : in spring.1987,9 " I
-l
~
following the autumn 1986 denuding (Fig. 8); by - L April May, maximum coverages at FE, FS, ON - =+ == =*u'== == ==
'-"*****"~*"""'"'-
=*.'s=+= ==<
and WP were 74,9.I,68 and 78% respectively. Concurrently, substratum _ coverages by barnacles IV s. Atiundance or sala,ua in zone 2 or recoloniamiion and in Zone 2 of the Undisturbed transects were 65, undisturtied trenneck, from SeNemkr 1981.Sepemkr 1999J
- ' - 77,68 and 60% tespectively. The slightly_ higher Vennt lines reement time of denudins..
values in the recolonization transects, relative to.
> 1
' Rocky Intertidal Studies . 207 M r + r - , -~ Yf
, ,. yp , r'.!
r
-t b
the undisturbed (avg. 79 vs. 68%), were attributed outumn ava-== outumn Evei #,_ to absence of competition for space with Fucus UUnin, - (NUSCO 1989). Maximum barnacle cover in ,, summer 1988 averaged 65% in recolonization transcets, and 63% in undisturbed transects. k . [p Average maximum ~ values in 1989 for g"- ; recolonization and undisturbed transects were 59 r- g
^
and 55%, respectively. A decreasing trend in * \ > < annual maximum barnacle cover is evident at FE, *
\ /w FS, and WP from 1987 to 1989. At FS, ON, and
== = == = ==
d
== =+ ==:='a
. WP there has been an increasing trend in annual
~ * * " ' " ~ * " " " "
minimum cover ever the same period. Both trends could be explained by a concurrently , agu,ma "-* ogu,ma developing Fucus canopy. The competition for ,,, ~6a, 4.nud c, space would reduce the upper limit of barnacic ,, abundance, but protection from desiccation would ., ,, r , reduce barnacle mortality and increase the lower .{ . / ., limit of abundance. However, patterns of Fucus 5 = / ]1 y ' abundance since 1986 (Fig. 9) do not entirely . I** ',V - VN , support this explanation,- since the above 1 mentioned trends in barnacle abundance were " observed at WP in the absence of extensive Fucus' ' ~ ~~'~ ~ ( ' cover, whereas a dense Fucus canopy at ON did
~" ***'* ~ ~*""""
not appear to inhibit barnacle settlement. Future n,onitoring of the recolonization transects will q ogma "-e agu,ma allow us to develop and test alternate hypotheses. , e.~ma, o.~#,,, During 1989, Fucus was a dominant alga in the
. \
re.id Micrtidal quadrats of recolonization and I =,. undisturbed transects at all stations. Annually, 5
- i maximum coverage of Fucus occurred in July (Fig. -[ a" ,/ 1 >
9). Maxima:In the recolonization areas at FE, FS, ON, and WP. were 65, 78. 89, and 30%, "' r /D
/ bI# T /v[ 4 respectively, . Maximum Fucus percent cover values in nearby undisturbed areas were 76,79,
= um = =
Q -
='a = w h- **a == ,
" " " * " ' " ' ~ * * " * "
47, and 15%, respectively. At cach station except WP, maximuti. Fucus cover in 1989 was highest , ;gma " - - " oggma siecc the transects were denuded in September ,, e.~ma, o.nue, 1986, and there has been a generally increasing , trend of Fucus abundance each year since . . denuding. 3 .o Correspondence between Fucus and barnacle r*" abundance in Zone 2 of the recolonization '" transects, compared to that in the undisturbed . (7 insects, and the similarity of seasonal patterns, ( ^'~ y f./ $/ j i are - measures . of the degree of community "' = = = * "'a = =b ' = ==
~ " " ' " ~ ~ ~ "
- recovery By these measures, it is apparent that-l recolonization areas so- CloScly . resemble Fig. 9. Abundance or fucus in Zone 2 of recolonization and
> undisturbed areas ' that recovery of - the mid
~
undisturbed transects, from September 1981. September 1989. intertidal (Zone 2) has been complete since two venical lines represent time or denuding. years after denuding (NUSCO 1989), i j 208 Monitoring Studies,1989 i i
7 The sequence of events leading to ,,,,,,,,, -.q..-,,,. recolonization of mid intertidal surfaces following ' "
!!'ho,- !!!k,,
the September 1986 denuding was similar to that ." seen following the September 1981 denuding. In , , , both cases, rock surfaces remained essentially [. j
- clear from the time of; denuding until the 5 = Tp/q'- 9' '
following spring, when barnacles settled and grew, [> provid$g surface heterogeneity and protection from grazing for Fucus germlingsi -These Fucus [ l germlings developed _into an extensive mid ' ,, w, h intertidal canopy, llowever, the rate at'which " * "* " *,, ",* ,,, "* ;,"2,J, " ** Balanus and Fucus. populations grew differed-somewhat between operational periods For ,,,,,,, ...... - . . , , , , example, maximum barnacle cover in Zone 2 of L
!!!L., !!!L,, _
the recolonization transects in spring 1982 (first ,, set after autumn 1981 denuding) ranged from St. . , , , 71% (Fig. 8). Corresponding coverages for spring [ 1987 (first set after autumn 1986 denuding) were : 1
- higher, ranging from 68 94% Additionally, the general trends of barnacle abundance noted after k" "
the autumn 1986 -denuding (decreasing armual maxima, increasing annual minima) were not ) ^'~';. _ _ _ [A_ DN apparent after the autumn-1981 denuding. Fucus "* "* "* "* "* "",,,,,"* ** "* development also differed between operational periods. Fucus settlement in the first summer ,,,,m,- ..... ,,,,,, ' after the 1981 denuding was low; percent coverage
!!!ko, !!!ke, values in' September 1982 ranged from <114%-
(Fig. 9). Fucus settlement-in the first summer . , , , after the 1986 denuding was much higher; [.[ 7 I rage in September 1987 ranged from 10 = y ~\ #- In short, recovery of mid intertidal populations 1 of Fucus occurred about one year faster during 3- .. k: unit operation than < luring 2 unit operation, and
]
the initial barnacic set was higher during 3 unit vs, 2 unit - operation. However, as thesc ,,,,,, differences were noted at -all . recolonization '"!!!k,, !!!k,, stations, they are attributed to; year to-year ,, variability in settlement and growth rates, rather [q ~//
/\h/
#g than to operation of Unit 3i Further, the .
convergence between barnacle and Fucus
@ \
C pJ . \[ ga abundances -in Zone 2 of the recolonization r"" transects and those. In undisturbed transects " implies that such variability can affect the rate, bu' ..ot the eventual outcome, of mid intertidal , ; ,A., _ k __ d
.ommunity development. "
- l * " *,, "_ ," *,,J * " " " * ..
IAw intertidal (Zone 3) rocky shore areas at Fig.10. Abundance or Chondms in Zone 3 or recolonihtion most sites in the MNPS region are dominated by -and undisturbed transects, from september 1981 septemter 1 l- Chondrus crispus' (cf. previous section), and 1989. Venical lines represent time or denuding. j L recolonization of denuded Zone 3 quadrats - 8 q Rocky Intertidal Studies 209 d
j i typically involves recovery of this species. During - Moderate water temperature increases accelerate l 1989, the third year after the September 1986 apical growth, which can be measured axurately denuding, maximum Chondms cover in Zone 3 of over time. Orcater temperature increases result . in deleterious effects, such as the gradual demisc ! the recolonization transcets was 3,6,10, and 28% at FE, FS, WP, and ON, respectively (Fig.10). or sudden climination of a population (Kanwisher . Values at WP and ON show a general increase 1966; Vadas et- al.1978; NUSCO 1987). %is - over time since denuding, but are still much lower ' . type of sensitivity, coupled with its perennial habit than those in undisturbed transects (78 and 62%, and mode of linear growth, makes Ascophyllum a respectively). At _ FS,- maximum Chondms useful and critical blomonitoring tool. Studies of 3 coverage in undisturbed transccts in 1989 was 8% Ascophyllum populations in the Millstone area - In both undisturbed and recolonization transects have been used since 1979 to assess the i npacts at this site, slitation makes substrata unsuitable. associated with the construction and operation of - for Chondms settlement (cf. previous section)c At MNPS. Results from the 1988-89 sampling year i FE, maximum coverage in undisturbed transects are discussed below and compared to results from- ' in 1989 was 1%; virtual absence of Chondms from overall 2-unit and 3-unit periods. this site since September 1984 is a rcI1cetion of the unsultable (for Chondrus) temperature Growth conditions that have existed since the opening of the second cut. _ Except at FE, recovery of 2:one . Many factors account for variation in apical 3 Chondrus following the 1986 denudings appears - growth rate of Ascophyllum, including: genetic
~
to be very similar to that seen following the 1981 growth potential (Stromgren 1981), duration of denuding (Fig. 10). Even _under favorabic . exposure to air (Stromgren 1977), competition for.- - conditions, re establishment of 'a C/mndrus ' light und spacc (Stromgren 1981; Cousens 1982),- population and associated species assemblage on degree j of _ exposure -- to waves : (Vadas 1973; , denuded surfaces takes a minimum of 3-5 years Causens 1982), and water temperature (Stromgren 1" (Ring 1970; Lubchenco 1980; NUSCO 1987). 1977; NUSCO-1989). . The average monthly tip - Continued monitoring of the recolonization lengths and predicted Compertz growth curves for transects will be necessary to assess recovery of Ascophyllum populations in the vicinity of MNPS - the low intenidal commumty. are presented in Figure 11. Growth data for the 1988-89 growing season are compared to overall' ;t Ascophyllum-nodosum Studies - 2 unit and overall 3 unit growth data for the ON, WP and FN sampling titesO At ON, a reference The- perennial brown alga, Ascophyllum site approximately 7' km west of MNPS, total l nodosum, is a dominant component of shel;cred length (a parameter . cstimate) was 97.0 :mm mlJ and low . intertidal rocky shores around during 1988-89,490.2 mm during7 the 2 unit MNPS. Intertidal distribution patterns similar to operational' period. and 855 mm during the first those described in our study area have been cited three -years of 3 unit operation. Ascophyllum throughout the species' geographical range, i.e., growth during 1988 89 was the greatest since Unit New Jersey to Baffin Bay in the Western Atlantic 3 began operation,Ennd was'significantly higher , (Taylor 1957), Portugal to the White Sea in the (P<0.05) than the 3 unit mean to date. Neither Eastern Atlantic (Baardseth 1970); its phenology, value was significantly different from the 2 unit 3 and ecology have been studied extensively (David- mean. The time of-maximum growth (inlicction- j 1943; Printz 1959; Baardseth 1970; Sundene 1973; point in the growth curve) at ON was August 3 J Mathieson et al.1976; Vadas et al. 1976, 1978; in 1988,;and July 29 and July 30 during the 3-- ;
. Keser et al.1981; Keser and Focrtch' 1982), unit and 2 unit operational periods, respectively. ,j
' Ascophyllum is sensitive to environmental changes Tip lengths at-WP,:a site approximately 1.7= km j
. (David 1943; Kanwisher 1966; Baardseth 1970; from MNPS, during 1988-89 (80.2 mm) and. In the l
! Cousens 1982);l In particular, its growth-- and combined ' 3, unit . period (84.4 ' mm) were -
'j*
overall persistence respond predictably to changes significantly shorter than the 2-u_ nit tip length in ambient water tempuature (Vadas et al.1976, value (90.1 mm).' Differences between'1988-89 1978; Stromgren 1977,19810 Wilce et al.1978). and combined . 3-unit - total > lengths were - not y significtmt. The in0cetion point was earlier in- 4 210 Monitoring Studies,1989 t
"" 1988 at WP (28 Jul) than during the 2 unit .and
- 3-unit operational periods. (3 Aug and 8 Aug,
'" respectively). . Ascophy//um tips at_. the present
' experimental station (FN) were significantly
)'*"'
- longer in 1988 89 (139.1 mm) than those tips measured during the 2 unit growing season (1985-
[^ jM 86; 89.7 mm) and the overall 3 unit period to
}*
date (101.9 mm). Mean Ascophyllum prowth for
)e, _g/ %,a, u.a e -,,,ai n ""'" 2-unit and 3 unit operational periods were also
* ~ * ~ ' -
- significantly different at FN, The inflection point-U.
._.. v .m. n,a - mue2 in 1988 occurred later (27 Jul) than in 1985 and '
combined 3 unit years (17 - Jul and - 18 ~ Jul,
, respectively).
os
'" Annual differences in Ascophyllum: growth at '
cach study site are due to natural variation of-y "" environmental parameters which appear unique to y cach site. Superimposed on this variability, [^ Sgpp;}N cicvated water temperatures affected Ascophyllum i i
)" i , gi una, n,i,a a _nnan-,o.a tip growth at FN by increasing apical growth rate and by extending the growing season. During the 1 7 '. _ ,, ,, , ,, ,,, first season when growth- of Ascophyllum was
_ r . . .t T1..i . m o n monitored at _FN (1935 86,- 2 unit /2-cut - conditions), water temperattites were 0-2*C -
, 3
. warmer than at GN and WP (NUSCO 1987). As . .
j a result of these conditions, differences in total- j Ascophyllum growth (a parameter) were not .j significant among stations in 1985-86. Unit 3 j *"' . M
.f began operation in April 1986; water temperature - !
[ ..
" p.; _
at FN was elevated up to 3 4*C for 3-4 hours i MV h f
. t, E '"
i cach tidal cycle, During' the next two growing I" seasons (1986 87 nnd.1987 88) .Ascophylhem tip *
' *d ,. c # emi.uno w.nu-m growth was slightly enhanced at this site relative
,,, -t; o ,,,, ,, ,,, to growth at the GN and WP reference sites
_ m o m..es Li_ nes-a, (NUSCO 1988b,1989),. reflecting the effects of major refueling shutdowns of at least one unit .! y during the period of spring through summer, the
,,, }
time of peak growth for Ascophyllum (NUSCO i 1989). In 1988-89, Ascophyllum plants at FN { were exposed to an uninterrupted 3-unit discharge ; J,] through the peak - growing season, and
',' 3,,.d T b[ Ascophyllum tips grew significantly longer than at
'l p . ; ..)7 control stations (139.1 mm vs. 90.2 and 80.2 mm, k* .' y Fig. 11). 3 I" j' This extended period of 3-unit rm i.ana - ma una-e., operation represents the highest 1 temperature
'4 . ;, g, , ,.
regime expected at FN. These conditions are q j 2-vni ro5l-84 -- so nu favorable for Ascophy//um growth, and similar to lig.11. <tscophplum growth, at cach station. Curves are the t se reporld at M prior to the opening of the-Gompcrte gneth nulel ritted to tip length data. including second cut (NUSCO 1986, 1987), innection phnts. lirror bars represent monthly mean lengths 22m i The responses of Ascophyllum during the A various temperature regimes observed at FN are Rocky Intertidal Studies 211 l i ? l i
l similar to those reported in past Millstone studies of intermittent exposure to elevated _ winter water (NUSCO 1986) at the original Fox lstand station temperatures - (resulting In _ higher? respiration (FO, k>cated ca. 75 m from the quarry cuts) from rates) and freezing air temperatures. Continued 1979-84,7 as well as by L other ; rescarchers monitoring of Ascophyllum populations at the identifying temperature effects on Ascophyllum. NUSCO study: sites is : necessary to evaluate
. (Kanwisher ' 1966; . Vadas et al. 1976, 1978; chronic, or possibly delayed c!fects of 3 unit /2-Stromgren 1977,'1981). Orowth data ut.FO for : cut conditions on Ascophyllum growth.
three different operational periods (and different temperature regimes) are - aho represented 'in Afouality . Figure 11. Prior to the opening of the second cut (1979 83),with one or both power plant units: Breakage of upright axes from a holdfast (plant operating, tip length at l FO was consistently ' loss); and breakage of viable apices at or below: greater than--at control sites (NUSCO 1987)n the tip tag (tip -loss)c are used as indices of - Water temperatures during that period were 2e . Ascophyllum mortality _ and environmental stress. 3*C above ambient and remained ccmstant during . Mortality can be caused by natural processes such - tidal cycles.~ ilowever, thermal and hydrodynamic as storms (Cousens 1982), ice scour. (Mathieson conditions changed during the.1983 84_ growing et al.- 1982),1 grazing 1(Sundene ' 1973), 'and season when the second quarry cut was opened epiphytization (Boney 1965)J Mortality can also (Aug 1983)J in the period immediately following utesult from human activitics, such as harvesting the opening of the second cut, when only Unit 1 - (Keser et al.' 1981), pollution (Rucness ' 1973; - was in operation, water temperatures at FO were Bokn md Lein 1978; Stromgren 1979,1980), and ' 7 9"C above ambient, reaching a maximum of ca. thermal injury (Stromgren 1977;: Vadas et al.- 27'C,- This temperature regime 'was clearly not 1976,'1978; Wilce et al.:1978; NUSCO: 1987).- optimal, and growth rate -decreased Aharply. Plant loss during the _1988-89 season and for 2-
~
Raics of respiration increase logarithmically with- unit and 3 unit studies are presented in Figure 12, temperature, . while - - photosynthesis _ remains with data representing'-'cach station. #At GN.- relatively constant (Kanwisher 1966; Brinkhuis et
~ _
- mean plant h>ss in 1988 891 (42.0%) was lower al. 1976). - In . carly 1984, both units ;were than-during 2 unit '(52.0%) and 3 unit)(46.0%)z operating, producing water temperatures 12-13"C - operation. Plant loss at'WP in-1988 89 (68.0%):
above ambient at FO. -- Thesc cicvated water -was higher thah the 2-unit and 3 unit mean values temperatures allowed rapid growth. until carly-- L of $4.3% and 55.3%, respectively.. At FN, plant - summer (June). liowever, - as ambient loss for 1988-89 ~ (78.0%) f was = intermediate t temperatures increased' with August - water
~
between the 1985 86: 2 unit (80.0%) and the temperaturc< at FO cxceeding -30"C, the ; combined 3 unit (69.7%) values.1Tip loss values 4 AscophyIlum population at FO was eliminated. at-GN, WP and FN are represented in Figure 13. Tip loss at GN during;1988 89 -was 68.8%, and ' Since 1979, Ascophyllum at the experimental ' was intermediate between mean tip loss values for stations has - exhibited a' wide ' range of _2-unit and 3 unit.' periods (75.1%' and 66.0%, . Icmperature related growth responses (from respectively). J At J WP: tip loss during fl988-89 < ambient . to upper lethal -limit;, NUSCO 1986, - (84.0%) was . higher than the means reported - 1989). Ascophyllum growth has been predictable during 2-unit (75.1%) and 3-unit (68.7%) periods. and a. shows direct. response to power plant _-_ Tip loss at FN in 1988 89 was 90.8%,-higher than H controlled . temperature : regimese . Although the combined 3 unit;mean value. (82.0%) and -i conditions aF FN appeared optimal for growth similar to the'1985-86 2 tinit value (90.4%). j during 1988 89, . long-term effects of water: ! temperature conditions at FE cannot be assessed The relationship - of Ascoj)hyllum _ mortality at this time. Vadas et al.-(1976,1978) reported _ among stations _in 1988 89 (Figs.12,.13) was initially;high growth rates for an Ascophyllum similar to 'that reported in previous - studies j population exposed'io a power station's thermal. (NUSCO 1988b,1989)J In general, mortality - 1 effluent, but low growth and high mortality during - (tmth plant and tip-loss) was higher at FN, ~an a second year of such exposure. They theorized exposed site, than at GN and WP, more sheltered that these plants failed to adapt to a second year g 212 Monitoring Studies,1989 .. l 1 j
)
1 a . slics. Year to year variability was considerable at a
- f :' *$ all sites, with no consistent arca wide trends. At l' 'k.t. ON, overall mortality was lov,cr in 1988 89 than j*
- I mJ,p'.=
2-unit or 3. unit operational means. Conversely, mortality at WP in 1988 89 was higher than either [" .} operational mean. At FN, mortality in 1988 89 ~ j ,, , was intermediate between operational means.
>,, The highest rates of mortality at all sites in 1988-F, - 89 and in previous years occurred from August through November (Figs.11,' 12), a period of O more frequent storms.
.4, 2+u~t +w 3 - v rut 1M8-89
..-=-a NUSCO monitoring efforts, and those of other a
rescarchers, show a strong relationship between the degree of exposure and Ascophyllum mortality k; (Baardseth 1955,1970; Jones and Demetropoulos f" '
\
.' 1%8; Vadas et al. 1976, 1978; Wilce et al.1978;-
[
~
q
~
Cousens 1982). Our mortality Indices only y ,, w account for partiallosses of an Ascophy//um plant. t ,, Each plant consists of a basal holdfast which can f, support dozens of ' plants' (our term) or ' fronds'- j
* ~ * * * (after Baardseth 1955; Cousens 1984) and possibly ;
o~, i
- hundreds of viable apices! The process of partial j
... : ... 3- ~i _ use-as plant loss-as a result of abrasion, along with j
,, ,._ annual dehiscence of receptacles in summer, '
y provides substantial input to the detrital pool.. x and is important for nutrient recycling (Josselyn
']\
and Mathicson - 1978, 1980). Growth of;
}" Ascophyllum germlings is slow and early mortality N is generally high (Knight and Parke 1950; Printz
)P,, i S Q y' #N 1959). In' order to . sustain population level <, .l
} h biomass loss- must E be . offset by vegetative l clongation and lateral proliferation of long lived y,, ,,, g,,, j individuals. Others have ' reported that i
. .. m e,n . . 1,.i wu-s$ AJCOP h yllum plants have a life span of 10 years or ;
more (David 1943; Baardseth 1970; Keser et al; i
="
mg, 1981); we have identified individuals in our area I N that were at .least 7 years' old. Persistence of-
~ ^ individuals, and maintenance of high coverage-I g" Kx over time at a given site, suggest that Ascophyllum j t ,, 4 is able to adapt to variable local environmental i b q conditions. At FN, Ascophyllum continues to bc J ,, $ ( %% a dominant species of the low and mid intertidal zones, although the possible mechanisms that ]
j could result in delayed mortality, as discussed in rn m. ..i - ou !
* ~ '
' ~
the Growth section, cannot be -. cvaluated at- 1 E
- present. Additional data will allow us to {
Fig.12, cophyllu or li y as nu t or rema n ng tagged termine H a long4ctm or CMonk decHne of I plants, at each station. Wlues during 1988-89 are plotted AJCOP h yllum is occurring at FN due to 3-unit j against means and ranges of 2 unit and 3-unit operational operation, i periods. i. Rocky Intertidal Studies 213 I
~~
^ ~
~7 Q, '"]- g . 7 ,
- f; 3 a .
- 1. ,
l m .mg . - - Since 1979, the only clear example of poweri ! m
-lN '
plant.rclated. Ascophyllurn mortality occurred ,at : .g
= \ the old Fox island Ascophyllurn station (FO), and :
Y'k ' in < the area within E 100 m of thel discharge. K* q N 4,*'" s% - Mortality data;at FO are summarized in Figures j
;" .'k T@% 12 and 13.S In the 2. unit /1. cut period (1979 83) plant loss 'and; tip loss values were 44% and
!. i C,,
d
.76.5%,' rcspectively, ?The second cut was opened : 1 _
j
, # ,, . during the 1983 84 growing season with one unit _ p operating;'in that period, plant loss was 80.0%, j
-%. and tip lossLwas 92.8% ; In 1984,' 2.unil/2. cut-. *
. . -om ... 5-t - me-et conditions caused temperatures to exceed lethal!
~
j
= . --limits resulting isp 100%1martality at FO.._ in'
- =
=
, qC,,k . spring .1989, sevcral young Ascophyllun plants 1
'g ::l j
Jwere observed in the vicinity of the FO site (cf.? ,! > k'i >
- the .Qualltative Studies'section of thisieport). .
I '"
. However, it.is unlikely that extensive recovery of ~
I '" , s
'% 4 Ascophyllurn at FO will occur,' given t.he unstabic.
f ,,, N- r, environmental conditions at that riite, resulting '
} ,,
\u '
from scheduled and unscheduled unit shutdowns, l
. j n : Recovery of a removed Ascophyllnin population is ;
* '~ * '* generally slow;.the critical: phase appcarsLto be- 1 O- ** * .
thef establishment Dund? growth' of germlingst 'i
.- 2 - a . som - 9:n.s>
-(Rucness 1973),1which may require specific and ' :
presumably rare environmental conditions-(Printz -- ,
?!
'a -*' ~
=
.1956). - .
q y, Summary / (m , . j '* g
}\ ,,
N Power plant +related alteration of environmental, conditions ll.c;, clevated water temperature, could --
#" 'hw N .affectnrocky> intertidal communities iri specific ra s.a o.. A areasy through diverscimechanisms.i c Ceitain - d
?
'c =
~
species 1would disappearfirLwater; temperature i
. . . m on .n .., ~ % _. o% . cxceeded .their lethal limitsior' conversely, these '
~ new conditions could allow introdu'ction of species
7 h , ,
- tiew- to the carca.. Elevated' water temperatures:
could extend : the J1ocaljspatial8 oritemporal u, distribution of; warm water tolerant species, 'or ' 3 i. \ could reduce the ranges of those species;already. 7m
-ia f Q(% N -
- near ' their ; physiological limits.' Also," clevated ,
temperaturcsi could . alter': . growth _ . rates,4 reproductive activity or seasonal periodicity of; e
#" local species,' or. perhaps affect herbisore'or.;
rn wo4. ow % ' **w
* -predator behavior Some or all of these processes s . m . . , , , .
< could, directly or: indirectly, alter, the competitive?
- 1 W..
7 gm ro ich ' . ro w - balance between ' intertidal speeles,- und would .
. result in a changed community.- - ~
JFig.11 Mephplum mortality, as number or remaining tips, at each station. Values dunng 1988 49 are plotted against means and ranges or 2 unit and 3 unit operational periods. These Erocesses , have been documented in I
.NUSCO Rocky Intertidal' Studies. Specifically, at 1 . , , .
E T
'2141 eMonitoring Studies,1989 5.
f
-t '
6
+h' y y 7 y ,+Eo - = *e?- m - e ,r w w=-
l Fox island Exposed, approximately 100 m from Bertness, M.D.19h3. Intraspecific competition the MNPS discharges, we observed climination of and facilitation in a northern acorn barnacle species whose physiological limits were exceeded population. Ecol. 70:257 268. (Chondrus crispus, Ascophyllum nodmum), and appearance of more temperature tolerant species Bokn, T., and T.E. Lein. 1978. Long-term (Sargassum fibrer'dala, Gracilaria rikvahiac). We changes in the fucold association of the inner have noted an extended growing season at FE for Oslofjord, Norway. Norw. J. Bot. 25:9-14. species characteristic of warm. water collections (e.g., Dasyn baillouriana, Bryopsis plumosa), and Boney, A.D.1%5. Aspects of the biology of the reduced occurrence of cold water species (e.g., seaweeds of economic importance. Adv. Mar. Petalonia fascia, Monostroma pulchrum) relative Biol. 3:105 253. to the seasonal distributions observed at other stations. We have documented enhanced growth Bradbury, R.H., LS. Hammond, and R.E. (tip elongation) at the experimental Fox island Reichelt.1984. Prediction versus explanation Ascophyllum site, relative to that et reference in environmental impact assessment. Search 6tations, Analyses of abundance data, from both 14:323 325. undisturbed and recolonization transects, show that the community at FE continues to be Brinkhuis, B.H., N.R. Tempel and R.F. Jones. affected by the 3. unit thermal plume. Specifically, 1976. Photosynthesis and respiration of barnacle and Fucus populations in mid and high exposed salt marsh fucolds. Mar. Biol. 34:349-intertidal quadrats are exposed to elevated water 359 temperatures for only a short time during each tidal cycle, and closely resemble those found at Clements F.E.1936. Nature and structure of the unimpacted stations. Conversely, low intertidal climax. J. Ecol. 24:252 284. 1 areas at FE are exposed to elevated water temperatures for 910 hours each cycle, and a Clifford, H.T., and W, Stephenson.1975. An characteristic community, including Codium, Ulva, Introduction to Numerical Classification. Po&siphonia, Sargassum, and Gracilaria, has Academic Press, New York. 229 pp.
~
developed in response to those conditions, i Connell, J.H. 1961. Effects of competition, The same studies and analpes indicate that the predation, by Thais lapillus and other factors effects of 3. unit operation on rocky intertidal on natural populations of the barnacle, communities are restricted to sites in close Balanus balanoides, Ecol. Monogr. 31:61 IN. proximity to MNPS; i.e., other rocky shore stations support communities that resemble those 1975. Some mechanisms producing found throughout New England. These structure in natural communities: a model and , communities have remained relatively stable since evidence from field experiments. Pages 460 this program began, in terms of species 490 in M.L Cody and J.M. Diamond (eds.) ; composition, cycles of relative and absolute Ecology and Evolution of Communities. abundance, and Ascophy//um growth and mortality Belknap Press, Cambridge, Mass. Cousens, R.1982. The effect of exposure to wave References Cited action on the morphology and pigmentation of Ascophyllum nodosum (L) Le Jolis in south-
- Baardseth, E.1955. Regrowth of Ascophyllum castern Canada. Bot Mar. 25:191 195.
nodosum After Harvesting. Inst. Ind. Res. Stand., Dublin. 63 pp. 1984. Estimation of annual production by the intertidal brown alga Ascophyllum 1970. Synopsis of biological data on nodosum (L) Le Jolis. Bot. Mar. 27:217-227. knobbed wrack Asconhyllum nodosum (L) Le Jolis. FOA Fisheries, Synopsis #38. 44 pp. Rocky Intertidal Studies 215 l
1 i, i David, H.M.1943. Studies in the autecology of ,1980.1 Scasonal influx and decomposition ~ .! Ascophyllum mulosum Le Jol. J. Ecol. 31:178 of autochthonous macrophyte litter in a north; 199 _ temperate estuary. Hydrobiologia 71:197 208. l Dayton P.K.1971. Competition, disturbance, and Kanwisher, = 0.W. 1966. . Photosynthesis and. j
- community organization: the provision and- respiration in some seaweeds.- Pages 407-420 i subsequent utilization of space in a rocky in , H. Barnes (ed.) Some Contemporary =
intertidal community. Ecol. Monogr. 41:351 Studies 'in Marine Science.' - George Allen - ; 389 Unwin Ltd., London, 1 t! DcAngelis, D.L and J.C. Waterhouse.1987. Katz, C.H. 1985.' .A noncquilibrium . marine. [ Equilibrium and noncquilibrium concepts in - predator prey interaction. - Ecology 66:1426-ccological models. Ecol. Monogr. 57:le21. 1438. l Dethier, M.N.1984. Disturbunce und recovery in - ' Kcscr M., a_nd J. Focrtch '1982. Colonization ::nd s j intertidal- pools: Maintenance of mosaic growth : of Ascophyllum ncxfosum. In? New: j patterns. Ecol. Monogr. 54:99 118.- ' England., Presented at the First international- i Phycol. C(mgr., Stt John's, Newfoundland,' Draper, N. . and - H. Smith < 1981, Applied - August 9,1982.
- {
Regression Analysis. John Wiley and Sons, . New York. : 709 pp. Keser M.,' and B.R. Larson.1984;: Colonization ( .;
- and growth dynamics of' three spccles of -
Geisciman, J.A., and O.J. McConnell. 1981. Fucus Mar. EcoU Prog. Scr.15:125134. Polyphenols in brown algae Fucus rcsiculosus ' and Ascophy//um nodasum: chemical defenses Kescr M., R. L Vadas, and B.R. Larson./1981} i against the marine herbivorous snail, Linorina ' Regrowth of Ascophyllum mxtosum and Fucus y hitorea. J. Chem. Ecol. 7:1115-1133. . resiculoms u.nder various harvesting regimes in Maine, U.S.Al? Bot) Mar / 24:29 38J
;j Grant, W.W.1977. High intertidal community ' .
development on a rocky headland in Maine, Knight, M., and M.W, Parke.' 1950.1 A biological, U.S.A. Mar. Biol. 44:'15 25. study of Fucus rcsiculosus L and F. serrams L: , o J. Mar. Biol. Assmc. U.K. 29:437 514c 1 Hay, M.E., W. Fenical, and K. Gustafson.1987. Chemical defenses against different marine Lance, G.N., and W.RrWilliams.1967.f A general i herbivores: are amphipods insect equivalents? . theory?of classificatoryJsorting strategies,' L l[ Ecology 68:1567-1580. Hierarchical systemsi Comput. J. 9:373 380. ~F llughes, R.N., and . C.L Oriffiths. 1988. Self. Lewis, J.R.'1964.bThe Ecology lof Rocky Shores.- ' thinning in barnacles and mussels: The English ' Univ. Press, London. J 323 pp. geometry of packing. Am. Nat. 132:484 491. . .
, _ : ji . ,
t Lubchenco, J._1978.c Plant species' diversity in a m ; Jones, J.E., and A. Demetropoulos. 1968. marine intertidal community: importance'of: i Exposure to wave action: Measurements of an herbivore food _ preference : and ' algal ~ , important ecological parameter on rocky shores competitive abilities. ' Am. Nat.- 112:23 39. on Angicscy. J. Exp. Mar. Biol. Ecol. 2:46-- T = '
- 63. .1980. Algal zonation in the New England _
. rocky intertidal community:.'an experimental Josselyn, M.N., and: A.C. Mathicson. 1978. analysis. Ecology 61:333-244.' g Contribution of receptacles from the fucold M Ascophyllum muhnum to the dettital pool of a . 1983. ' Littorina and Fucus: effects of - .
north' temperate estuary. Estuaries 1:258 261. herbivores, substratum heterogenelty, and . g 1 i 4f 216 Monitoring Studies,1989
]
a
, N
l plant. escapes during succession. Ecology. the marine environment of Long Island Sound M:lll6.ll23. at Millstone Nuclear Power Station, Waterford Connecticut. Annual Report,1984. Mann, K.ll,1973. Seaweeds: their productivity and strategy for growth. Science 182:975 983. .1986. Rocky Intertidal Stndles. Pages 1-38 in Monitoring the marine environment of Mathieson, A.C., EJ. lichre, and N.B. Reynolds, 12mg Island Sound at - Millstone Nuclear 1981a. Investigations of New England marine Power Station, Waterford Connecticut. i i algae 1: A floristic and descriptive ecological Annual Report,1985. study of the marine algae at Jaffrey Point, New ilampshire, U.S.A. Bot. Mar. 24:521 532. 1987. Rocky Intertidal Studies. Pages 1 66 in Monitoring the marine environment of ' 3 Mathieson, A.C., C.A. Penniman, P.K. Ilusse, and Long . Island Sound at Millstone Nuclear , E. 'IVeter Gallagher 1982. Effects of ice on Power Station, Waterford Connecticut. Ascophyllum nodosum within the Orcat llay Summary of studies prior to Unit 3 operation. ! estuary system of New llampshirc-Maine, J, j Phycol. 18:331 336. .1988a. Hydrothermal Studies. Pages 323-354 in Monitoring the marine environment of Mathieson, A.C., and J.S. Prince.1973. Ecciogy Long Island Sound at Millstone Nuclear of Chondrus crispus Stackhouse. Pages 53-79 in Power Station, Waterford Connecticut. M.J. liarvey and J. McLachlan (eds.) Chondrus Annual Report,1987. crispus. Nova Scotlan inst. Sci., llatifax. ,
. 1988b. Rocky intertidal Studies. Pages Mathieson, A.C., N.11. Reynolds, and E.J. Hehre. 1156 in Monitoring the marine environment -
1981b. Investigations of New England marine of Long Island Sound at Millstone Nuclear ; algae 11: The species composition, distribution Power Station, Waterford Connecticut, i and zonation of seaweeds in the Great llay Annual Report,1987. ! estuary system and the adjacent open coast of l New Hampshire. Bot. Mar. 24:533-545. . 1989. Rocky intertidal Studies. Pages j 123-157 in Monitoring the marine ! Mathieson, A.C., J.W. Shipman, J.R. O'Shea, and environment of Long Island Sound- at i R.C. liaseviat. 1976. Seasonal growth and Millstone Nuclear Power Station, Waterford reproduction of estuarine fucoid algae in New Connecticut. Annual Report,1988. j England. J. Exp. Mar. Biol. Ecol. 25:533-545. ' Paine, R.T., and S.A. Levin.1981. Intertidal Menge, B.A.1976. Organization of the New landscapes: disturbance and the dynamics of ! England rocky intertidal community: role of pattern. Ecol. Monogr. 51:145-178. predation, competition and environmental heterogeneity. Ecol. Monogr. 46:355 393. Printz, H.1956. Recuperation and recolonization j in Ascophyllum, Pages 194-197 in T. Braarud ; Menge, J.1975. Effects of herbivores on and N.A. Sorenson (eds.) Second Int. Seaweed a community structure on the New England Symp. Pergamon Press, London. rocky intertidal region: distribution, abundance, k and diversity of algae, Ph.D. thesis, Harvard 1959. Investigations of the faiinre of Univ.164 pp. f recuperation . and repopulation -in cropped Ascophyllum nodosum. Nctske Vidensk. Akad. [ i Murray, S.N., and M.M. Littler. 1978. Patterns K. Mat. Nat. Kl. 3:1 15. of algal succession in a perturbated marine , intertidal community. J. Phycol. 14:506-512. Ring, P. D. 1970. Developmental and , ecophysiological studies of Chondrus crispus ! NUSCO (Northeast Utilities Service Company). (L.) Stackh. M.S. thesis, Univ. Maine. 73 pp. 1985. Rocky Shore. Pages 141 in Monitoring l Rocky Intertidal Studies 217
L R'u eness, Jl 1973. Pollution = cffects on littoral' .1981L Individual variation in apical growth" algal communities in the inner Oslofjord, with. rate-in'Ascophyllum nodosum (L) Le Jolis; speciali reference 1 to - Ascophyllum ' nodosum. Aquat. BotJ 10:377 382.- Helgolander=wissi Meciesunters 24:446-454.' Sundene,0; 1973; Growth and reproduction'in' Schneider, Cl We 1981; The effect of clevatedi Ascophyllum nodosum (Phaeophyceae). Norw. temperaturei and' reactor- s,hutdown' on- the - J; Bot. 20:249-255c benthic marine flora of the Mllistone thermal > quarry, Connecticut! J. Therm; Blois 6:16c Taylork W.Ri 1957. Marine- Algac? ofE thel Northeast Coast of North America.i Univ, of'
, M;M! Suyemoto, and C, Yarish; 1979c An -
- Mich Press, Ann' Arbor; 870 pp.
Annotated Checklist of Connecticut Scawceds; State' Geol! and-Natl Hist; Surv. CT Dept of . - Vadas, R li l1973i? Attached Algae. - Pages 195 Environ? Prot., Bulli-1078. 20 ppi ' 261 in Survey of the hydrography, sediments: plankton, benthos and commercially important' Schonheckb M.W.. and : T.A; Norton. 1978. . plants:andf unimaisiincluding finfish, in- the Factors controlling the upper limits of fuccid~ Montsweag: Bay Back: River area: algae on the shorci JJ Exp. Mar; Biol; Ecol.t Preoperational1 Summary l Maine! . Yankee ;
.31:3031313! Atomic Power Company.
.1980/ Factors controlling the: lower limits' - Vadas, R.Il, Ml Kescre and ' P.C. Rusanowski?
of fucold-: algae on the shore.- Ji Exp! Mar; 1976c Influence. of: thermal loading on: the-Biol! Ecot: 43:131 150. ecology of intertidal algae. ~ Pages 202 251 in G.W. - Esch' and: R.W. MacFarlane. -(eds.)t Sousat W.P.1984i-Intertidal mosaics: Patch size r Tliermal Ecologyt 11) : ERDA< Symposiumi propagule availability, . and ' spatially 1 variable; Series, Augusta, GAz patterns of' succession;' Ecology 65:1918-19351 11978. Effectjof reducedncmperature.on-Southwarde A.Jl,; andi E.- C." Southward.i 1978.' previously stressed populations of an intertidal l Recolonization"of rocky: shoresiin Cornwall' algaf Pages 434 451)in 3.11l Thorp and'G.W.- after:use of toxic dispersants to clean up the Gibbons 4 (eds.)! : DOE : Sympostum Series; . . 7 berry Canyon spill l Ji Fish; Res; Board Can; Springfield,tVAL (CONF-771114; NTIS); 25:682-70 0
}1 j 1
Wethey, D.S; 19835 Geographical limits and local t ' R
];j
~
StephensonlT.Ac, and:A. Stephenson.1949c The . zonation: the o barnacles > Semibalanus and' universal + featurcst - of- zonation between Chthamatusl in t New England! Biol. Bull.; tiddmarkstonirocky coasta; J! Ecol. 38:289< 165:330 341.' ' 305. Ei Wilee, R.T;, J! Foerich, WiGrocki,: J! Kilar, H! l Stromgren,> Ti 1977.- Shortaterm 4 effects' ofi llevine, sand -J.L Wilce.1978; Flora: Marine-
]
temperaturci upon s the growth : ofiintertidali Algall Studiesi . Pages E307 656 ini Benthic: -! fucates. J! Exp;" Mar. Bioll Ecol l 29:181 195; Studiesiin;the~ Vicinity of Pilgrim Nucleart '!
~'
Power: Station, 19691977l ' Summary Rpt.', -
<!979c' The effect:of copper:on" length 4 Boston Edison Coc increase in~Ascophyllum nodosum (IL) Le Jolisc
.: JJ Expc Mar! Biol; Ecoli 37il53-159/
J
,1980f Th'c:cffect iof: lead / cadiniumi and ;
mercury / ont the J increase ' inilength" of 4 five > f intertidal!Fucates? J! Exp. . Mar; Biol.! Ecol.i 1 43i107119J q 218': Monitoring Studies,1989 - y
- l
)
s 1 Contents Manne Woodborer Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221-I n t rod u ct io n . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221 .j Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - 221 i
- Exposure Panel Study ...............................
. 221 j 1
Discharge Study ................................... 222 j Data Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 l Exposure Panel Study Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224 i Water Te mpera ture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .224 Fo uling Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .225 Wood boring Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - 228-Percentage of Wood . loss ............................. 233 Exposure Panel Study Discussion .....................,....... 234 Discharge - Study Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . _ , 236 Discharge Study Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 Co n cl u s ion s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238-References Cited .................................. 238-A p pe n d ix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .....
..... 241
x l { Marine Woodborer Studies Materials and Methods Intnxtuction Etposure Panel Study Marine woodborers, including shipworms (Teredo narolis), Isopods (Limnoria spp.) and Woodborers and fouling organisms were amphipods (Cheluro rerebrans) arc distributed monitored by submerging six wooden panels at five sites: White Point (WP), Fox Island (FI), Black world-wide (Turner 1966; Kohne 1975). Although these borers are beneficial- (l.c., accelerating Po nt (BP), Giants Neck (GN), and Effluent (EF) (Fig.1). The EF site, located within the Millstone decomposition'of wood, which would otherwise accumulate in harbors and estuaries), their Quarry, is considered impacted; F1 and WP are located approximately 400 m and 1700 m from the . destructive nature requires extensive preventive maintenance by marina operators, boat owners and discharge cut, respectively, and are-within the predicted discharge plume (NUSCO 1988b). The lobstermen. Several mvestigators have reported that operations of coastal power stations can affect BP and GN sites are located over 4 km from the kical woodborer populations. Increased Millstonc Quarry discharge point and serve as our reference sites. abundances of shipworms have been reported near power plant discharges at Swansea, Wales, UK (Naylor 1965) and at Oyster Creek, New Jersey, At cach site, six knot. free pine boards (25.4 x 8.9 USA (Turner 1973). The extensive damage to x 1.9 cm) with one' face covered with plexiglass were bolted to a stainless stccl rack and, in turn, marinas near Oyster Creek Nuclear Generating Station (OCOS) was attributed to increased growth attached to a stainless stcci frame (Fig. 2). The of shipworms. Tius - increased growth was pancis at all sites were suspended from docks and attributed to elevated water temperatures from positioned 0.2 m from the bottom. From August
~
OCOS (Turner 1973; Hoagland 1983). Hoagland 1985 to February 1987, the rack and frame (1981,1983) suggested that immigrant populations ~ M EF wu gM -10 m W h (Teredo bartsch and T. fiercifera) within Oyster surface and varied with the tide from 0.5 to 1.5 m Creek could adapt to cold water and cause off the bottom because they were attached to the increased wood destruction in areas beyond the Floating Lab. Before 1985, EF pancis were influence of the OCGS discharge. suspended one meter below the surface and about 10 m from the bottom. Despite differences in The marine woodborer studies at Millstone panel I e tion at EF, there were no significant Nuclear Power Station (MNPS) were conducted to renes M@ in sWwmm recrubent m
- 088 # *##" * * " " "U" E""
- evaluate whether operation of MNPS has influenced the abundance, activity (amount of I^PE*" b wood loss) or distribution of wood. boring species m the vicinity of MNPS. The Exposure Panel Pancis were deployed in February, May, August Study monitors the abundances of fouling and and November and collected six months later in wood boring species, and quantifies wood. loss, No ember, February and May, providing The Discharge Study monitors densities of Tered four gosm pia M oml@ @ n navalis, the native shipworm, and T. barrschl, a by three months. At the start of each exposure warm water immigrant, at various distances from period, one rack of panels was removed , for the power station. This report examines data processing and a new one was - deployed.
collected during 1988-89, and comparcs these data Throughout this report the exposure periods will. to total 3-unit (May 1986-August 1989) and 2 unit - de referred to as follows: Feb-Aug May-Nov, Aug Feb and Nov-May. Each abbreviation consists (November 1978-Nosember 1981; February 1985-May 1986) operational periods at MNPS. of the month of panel deployment followed by the month of panel collection. Marine Woodborers 221 ll i a u ' ' ' - . _ _ -
Sites: Exposure Ponel Study
) p wt.It. U.OP GN A(# 0km] 1 Distrit>ution 5tudy ino m - : ioon .
North Y im
)
1 ma ! f4 i u.et.c sw ,,3
- n hA "{ ~ we een w i -;
. X '
Fig.1. tecation or expanure panel sites in the vicinity of the Minstone Nudear Iwer station (WP = White Point, FI = Fox tstand. EF .-
= limuent the Mdistone Quarry ducharge, HP = lilack Point. GN = Oiants Neck c a = the transect line along which tou,200, .
500, and 1000 in panels are set.
-1 Pancis were processed immediately after juveniles collected at WP, FI, BP and GN were collection or frozen for later processing. The classified as T. navalis in data analyses of shipworm l 4
uncovered wood side of each panel was examined, abundance. At EF, Teredo juveniles were assigned. ; and percentage of cover (referred to as " cover" in to Teredo barrschi or Tcredo navalis based on size ' this report) was estimated for organisms that of the indivictuals and time of settlement. occupied more than 1% of the panel surface. Abundance estimates for barnacles, Limnoria, Wood. loss was expressed as the percentage of - , Chelura and mussels were obtained by counting the weight lost from a panel- during an ' exposure i 3 number of organisms in six 6.45 cm subsamples, period. Before deployment, pancis were dried at evenly distributed between the upper and lower- 80'C to constant weight.- After collection and halves of the panel. If an organism was observed removal of shipworms, panel fragments were acid on a panel, but not included in any of the six stripped in 10% hcl to remove CACO3 tubes, subsamples, it was assigned a density value of one. soaked in freshwater, and dried to constant weight. After etwerage estimation was completed, pancis Dhcharge Sfudy were taken to the Northeast Utilitics Non-destructive Testing Facility in Berlin, CI' for his study examined distribution and abundances radiography, These black and white images were of Teredo navalis and Teredo bartschiin the MNPSi used to count shipworms (Teredo navalis and discharge mixing zone by sampling panels placed at ! Teredo bartschi) in cach panel. All or at least 100 100, 200, 500, and 1000 m from the Millstone 4 shipworms from each site were removed from Quarry cuts (Fig.1). The site at 200 m was added .i pancis for identification. Shipworms s$ mm in - to this study in 1988. Five panels were attached to - length were classified as Tcredo juveniles because cach of three lobster pots on a. trawl line and i their pallets were not sufficiently developed for deployed on the bottom at each distance (Fig. 3A).- accurate identification. Because adult T. barrschl During each sampling period, three pancis from were not found at any site except EF, Teredo each pot were collected and replaced with new ones; shipworms inhabiting the remaining panels l 222 Monitoring Studies,1989
h pi,q,,, A. TRAWL-UNE , es. i s I N e, "m Q ~,,, , , , , , , rs u., ~ I m j%.'.3 .%. h N g y
..s.- .+
p
~
N (l- ]i hS S. p h(
- j B EXPosVRE PANEL s**wda'**
**+ w e.es
[ 3@ 40
? s s A -_A l'ig. 2. Frame and rock assembly used for holding six month, six.rephcate exposure panels. Fig. 3. Diagram of an exposure panel trawl-line used to sample ,
the distribution or shipworns in relation to the efDuent ! served as a source community. Initial study design discharge point at the Minstone Nuclear Power Station. (A. included two 6 month exposure periods (May Nov trawMne of nve i tuter p ts with the locations of the 15 pine paneN B. pine panels showing the sectk.ns for subsampling). and Nov May). However, due to severe wood loss observed in November 1985, the sample design was Water temperatures were obtained from the modified to provide a shorter (5 month, May-Oct) exposure during the period of maximum settiement Northeast Utilities Environmental Data and growth of shipworms, and longer (7 month, Acquisition- Network (EDAN) sptem, which Oct May) exposure during the period of low continually records temperatures at 15-minute infestadon. intervals. Ambient water temperatures were the averaged values obtained at the Unit I and 2 i From 1985 87, six randomly chosen sections intake bays, while discharge temperatures were the (Fig. 30), one from each of six panels collected at amage va ucs at k w quany cm l cach distance in October, were used for shipworm l counts and identification. When smaller numbers Data ha%. of shipworms were present (i.e., May Oct 1988 at 100 and 200.m distances), all shipworms were This report presents data collected for the I removed from the entire panel and identified. Exposure Panel Study from November 1978 to When moderate densities occurred (i.e., at 500 and November 1981 and from February 1985 to August 1000 m distances), shipwomis from four sections of 1989. Monitoring of exposure panels was cach panel were removed, counted and identified. suspended from November 1981 to February 1985 This strategy provided an adequate number of to investigate the life histories of two shipworms, shipworms for identification and permitted more Teredo navalis and Teredo banschi, in relation to accurate estimates of shipworm species abundance seawater temperature (NRC 1981). At each site, and distribution which occurred outside the four exposure periods have been sampled each year Millstone Quarry, including six replicate samples per site. Data collected at four sites (WP, FI, EF and GN) during All nine panels collected in May were processed, 2-unit (1975 86) and 3 unit (1986-89) operation because shipworm densities were low. Panels were are compared on the basis of three or four years of examined for shipworms by X ray photography, samples, . depending on the exposure period. using methods described in the Exposure Panel Panels at BP were first collected in February 1986; Study. This technique identified the location of data from this site include only two 2 unit shipworms within panels, allowing more efficient exposure periods. Unit 3 began commercial processing. operation April 1986, and although some Marine Woodborers 223
Intermittent operation and testir4g of circulation Exposure Panel Study Results
. pumps occurred before this date, we have considered sampling periods from Nov May of IVater Tentperature -
1979 to Nov .May of 1986 as 2 unit operation. At the EF site, 2 unit and 3 unit operations were Average monthly intakc (ambient) and discharge compared using data collected from surface pancis water temperatures from November 1978 to May from 1979 to 1981 and data from bottom pancis 1986 (2 unit period) and from May 1986 to August collected from 1985 to 1989. 1989 (3 unit period) are presented in. Figure 4. During 1988-89i average intake and discharge Data were summarized by exposure period (Feb-- temperatures were within the seven year range. Aug, May-Nov, Aug Feb, Nov May) and flowever, July September 1988 and November: abundances were expressed as mean percentage of W88 January 1989 discharge temperatures were cover on panel surfaces and/or density of-0.91.3*C and 2.12.5'C warmer than the average individuals (identifiable adults and juveniles) per temperature during 2 unit operation. In February' panel. Fouling species, except for barnacles and and - April.1989, discharge waters were 1.5-1.8'C mussels, were described only by cover data and
~ colder than the 2-unit average, wrc not reported unicss average values for a taxon were equal to or greater than one percent during the -current year, or during 2 unit or 3-unit During this study, cach exposure period was characterized by a' specific tempenture regime, operation. The coverage ofliving and dead foulers were combined to assess recruitment of each During the Aug Feb period, tempoures decline from summer to winter, averaging 9.0*C at intake species and the effects _that they have on (range 21.2 ;to 1.0*C) and = 19.0*C within - the -
wtxxiborer abundance. Coverages of empty tests discharge (range 34.2 to 8.7'C); The inverse' is, ! and basal plate remnants of barnacles were not assigned to a species grouping, but were reported F6 %- h m as Dead Balanus. Abundances of barnacles and higher at both the intake (average 13.7*C; tange mussels were described by both coverage and U M* W within the discharge (average density d ita. Wood.txiting taxa were described by 23.8'C; range 3,7Jt o 34.2 *C) ! Temperatures in Nov May are coldestf averaging 6.0*C at intake density data only. (range 1,1 to 13.0*C) and 15.7'C in the discharge: i (range , t Since 1985, wtxxt loss was calculated as the 6T). Warmest mndidons oww percentage of weight lost from a panel during an in a# w.w n watu tempuatum amage-16.7'C at intake (range 8.2 to 21.3,C) and 27.lT exposure period. Data collected prior to 1985, , when wood loss was visually assessed from within the discharge (range 16.1 to 34.2,C). radiographs, were converted to weight based data using a r6 bust linear regression model. The results During 3-unit operation, water temperatures of . ! of this analysis can be found in NUSCO (1989). the discharge during winter (minima) and summer l
; g 3 Data shown in histograms summarize the unit operation. Within the discharge, water annual variability of covers and densities, while '#*PC'"'*" d"ing . 3 unit ? operations . have those shown in tables provide a comparison of data rm ed awe 5.C during the wmter and have !
collected during 1988-89 with that averaged over 2-not exceeded 33,C.for more than six days during- j unit (1979-85) and 3 unit operation (19689). ""Y'"**"* ".mntrast, pa% amage dscharge ; The 1988 89 report year includes: May Nov 1988, ***P""'"res C pested im mer two weebin - , and . In adM n, summu maxima Aug 198%Feb 1989, Nov 1988 May 1989 and Feb-Aug 1989 exposure periods. (>33.C) were more common during 2-unit than 3-Statistical comparisons, using the Wilcoxon signed rank test, unit operation, and lasted for periods in excess of-were made between the two operational periods if two we& (M8, W, N, W82, N and N). l species abundance in both periods had mean values kl. q 224 Monitoring Studies,1989 i
.j i,
a
'E
;l
#U ~
Aug-feb i Feb- Aug > 35 35 l
' f 30 %g ,
'30 25 20
, % [. :$
'I
# j,/'g--"4 af' to 49 -20 y;5' C
q 0 D # f'1 _ 0 0 .AUG . SEP OCf NOV DEC JAN RCD FEB MAR - APR MAf 'JUN JUL . AUC :
'0 40 .i Nov-May Moy-Nov 35 33 (
30 30 pg N 25 -
- l '+*
=
b 10 m.wp/ i 10
,,f %g .
N > pt, 1
%}, - ,, -
5
. p
- o. O NOV DEC' JAN FES MAR APR MAY. MAY JUN. -JUL " AUG - -$EPJ .. OCT ._ - Nov ;
l'ig. 4. De average monthly seawater temperatures at Unit I and 2 intakes (lower curves = ambient temperatures) and in the MNPS ~ (( discharge (upper curvesacrtiueru temperatures) during rour exposure periods or the Exposure Pancis Progrant :%e monthly averages ? , are from the 15* or one month to the 15* or the next (-h- average temperatures trom November 1978 to May 19% vertical bars i y represent the rar.ge of average monthly temperatures over this seven year, trve month period or 2 unlt operation; - - average temperatures 1 [ during 3-unit operation, May 1986 to August 1989; o average temperatures during the current sampling year, May 1988 to August 1989). .< g l- Fouling Species EF, cryptosula pallasiana, B. crenatus and Balanus : juveniles characterized assemblages:at FI and . l
- Fouling of exposure panel surfaces results from ~ Codium fragile, C. pallasiana and Schizoporella -
I the settlement and growth of a variety of marine errata were most abundant at BP.' Since February-plants and animals. Because this fouling can . 1986, coverages ' have bcen highest at FI (8.0- Ji influence woodborer settlement on our panels,- 98.2%) and BP (12.6-84.5%) and ' lowest at. GN - y abundance of major fouling taxa was assessed (0.5 51.2%). based on their percentage of cover on the panel- , surface. In addition, the number of solitary . The majority of fouling species collected during L individuals (e.g., barnacles and mussels) present on our study exhibited strong seasonal periodicity -
. panel surfaces was determined. Cryprosula pallasiana and Schizoporella errata were :
most abundant on panel surfaces during the Aug. . - In terms of panel surface coverage (percent),31 Feb and May Nov exposure periods -Covers of . ! different taxa and fouling categories (e.g., dead Balanus juveniles,'Mytilus edulis and' Laminaria i
~
barnacle tests), accounted for the majority of panel .'saccharina ' generally: peaked duringi Nov-May. fouling during the three operational periods (Table : Balanus balanoldes, B. crenatus and empty barnacle .
- 1) and cornprised over 70% of the annual surface - tests usually peaked in- Feb-Aug. ' Covers:of B. 4 fouling shown in Figure 5. The dominant surface eburneus generally peaked In'May-Nov.' q foulers are consistent from year to year. _During i 1988-89, Balanus eburneus was most abundant zit '
Marine Woodboters 225'~ l 3 l
, > r
~
l-TAlllE 1. Average percentages of cover for foulmg organisms on ex;usure panets during the current samphng year (1989, l c., Novemter 1988 through August 1969) during 3 unit (3 U) operation and durms 2 unit (2 U) operation.
$!Tl! )ROANISM EXPOSURii PERIOD Augfeb Nov.May Feb Aug May Nov 89 3.U 2U 69 30 2.U 89 3-U 2U 88 3-U 2-U E!*' Almwidmin app. 0 0 t' 0 t 10.7 0 0 0 0 0 0 llalarua crrnated 0 t- t I 6.6 10.1 0 t 0 0 0 0 N/arus dead 4.1 16 4 i 4 20.8 8 83 1.6 t i 19.8 Alama rburncus I t 2.7 0 0 0 9.7 - 2.8 3.7 1 3.1 11.0 Ntarua improvirus t 2,$ 21,7 0 t 3.4 1.9 t 9.4 I t !!.8
#alanus juveniles 0 t 1.0 t i 1.8 t 1,7 t i 10.2 frupla spp. t 4.0 t- t 2.0 t 0 3.2 4.5 3.9 14 Callishamniem rowurn I t i 1.7 t t 0 0 0 0. O t Cr>pmsula pallastana t I t 2.2 1.4 t 1.$ 1.0 t 0 0 t bictridiurn senile O t 0 0 t t 0 t 1.2 0 t O Alycale fibretihs 0 0 0 0 0 0 0 t 0- 0- 1.1 0 Afysiha cdulu t t 1.6 0 1.9 16.8 0 0 0 0 0 0 7kbularia crocca 0 0 1A 0 t 3.8 0 0 1.5 0 0 t Total i 106 44.8 3.9 11.9 67A 13.0 15 3 19.1 4.5 &l 54 4 l'1 Nianus balarusdes > 0 0 0 0 0 t 13.1 0 0 0 0 Nianus crenana 1.4 t t 20 3 61.2 35.2 t 14 3 143 0 t t l Nianus dead I I i 1.7 I t 1.7 28.2 15 3 1 2.8 10.2
#alanas <burncus 0 0 t 0 0 0 t- I t 0 t 1.1 Balanks irnfror$Juf I I I t t i 1.2 l 1.0 t t 2.1 Ntanus juveniles 1.2 t t 45.0 21E 12.1 i L I t t 13 theyllus schloucri 0 0 1.1 0 0 0 0 t t 0 0 0 thspla spp. t t 14 0 0 0 23 i t 38 2.7 la j Cryplasula pallasiana 24.5 41,2 63 0 0 t t t 6.0 34.5 40.5 23.7 ;
Electra crustulcrua t 2.6 0 0 0 0 t t i 20 t 0 l Alpilus edutiv i i t 1.0 t t t t t 0 0 t i Alfssa verrucosa 0 0 0 0 0 0 0 0 3.6 0 0 0 Schiroparella rrrata 6.0 3A 0 o 0 0 t 1.0 3 43 2A 0 Spirurbis ashes t t t 0 0 0 t t t I.2 t t 50rla spp. 0 0 0 0 0 0 0 t t 0 1 2.0 Total 33.1 47.2 9.0 67.5 83.0 473 5.2 $6.6 40.2 47.8 4sA 33.8 ! IIP #alarua balanoides 0 0 0 0 0 0 40 21.9 -- 6 0 0 - Balarua errnana 0 0 0 t 1.9 6.7 8 93 - 0 2,0 - Balanut dead 1.2 t t t t i 1A 4.8 - 2.0 19.6 - i Falanas churneus 6.8 2.5 0 0 0 0 t t - 1.5 2.1 - Balama improvissa 73 2.7 t 0 0 2.0 t t . . . 2A 1.2 -- Nianus juveniles t t t 4.2 7.0 - 4.0 t t ~~ 0 0 - Botryllus schlosseri 0 2.9 24 0 0 0 0 t - O t - Codimn fragile 29.0 10 6 273 0 0 0 0 0 - 13.0 43 -- Crysdula app. O t 0 0 0 0 1.5 t -- 0 0 -- Cryptasula pallasiana 16.4 - 2R6 4.0 0 0 0 t t .-- 21.0 '21.7 - iktbesia snarina 0 3.8 0 0 0 0 0 'O . 0 13 - { l.aminaria saccharina O t 0 9.2 9.4 8.8 t t - 0 0 - i Muccid worm tubes 0 1.1 0 0 0 0 0 0 - 0 0 - Sabellaria vulpris I .0 t 0 0 0 0 0 t - t t - Schisoporella errara 3.5 5.9 : 0 0 0 1.5 2.8 - 33.0 20.8 - Spirorbis tuto t t t 0 0 0 t t . t IA - Total 65.2 58.1 33.7 13.4 183 21.5 8A 38.8 --- 72.9 74A -- 226 1Aonitoring Studies,1989
l l l TAllt.fi I. (ct mrd) SITli ORGANISM EXPOSURii Pl:RIOD Augfcb New.May 17et>.Aug May.Nov 89 3-U 20 89 3 t! 2.U 89 3.U 2.U 88 30 20 WP llalanus crenatus t t- t 1,0 10.7 10 8 1.0 22.5 66 0 0 0 llalanat dead I t 1.5 I t 3.2 10.6 8.2 1.9 3.0 llalanta churncut 0 0 t 0 0 0 t t 2.9 0 t 5.9 flalanus inifrewisnt t i 1.2 I I t 0 t 1.2 0 0 1.2 Italanut juveniles t I t 7.7 11,7 4.6 : I t 0 0 2.2 llotryllus schhuicri 0 t 12.0 t t t 0 4 13 0 0 t-flupsla spp. I 1.5 t 0 0 0 4.3 3.1 1.7 5.0 3.0 1.7 Cmlium fragile 1.9 t t U O O O O t t t l Cryptamla pallariana 20 7.9 24 0 0 t 0 t 2.0 13 1.6 - 7,7 ikrbe.sla rnarina O l.2 8 0 0 0 0 6 t 0 t t flalecium app. O i 1.2 0 0 1 0 0 0 0 7.2 - 0 llaliclumdria spp. O I t 0 0 0 0 t t 0 1 1.5 f.aminaria saccharina 0 0 1 1 1.8 5.8 0 0 t. 0 0 0 i Schluperlia crrata 7.2 2.9 t 0 0 0 L t t 7.0 15.8 lA ! Total 11.1 13.5 18 3 8.7 24.2 24 4 53 36.2 23 9 133 29.5 24 6 ON llalanut amlWtrhc 0 t t 0 0 0 0 0 t 0 0 1.7 Italanus balarusides 0 0 0 0 0 0 0 2.5 0 0 0 0 llalanni crenatus t i I t 1.7 11.4 0 66 13.9 0 0 1A lialanus dead i i 1.8 1 13 1 14.2 12.6 t t 1.6 flalanus churncta 0 0 0 0 0 0 t t t 0 0 5.1 Italama knprmuns t t t 0 0 0 0 t t t t 1.5 llalamu juvemles t I I 2.2 9.4 63 0 t t t i 3.2 flotrvilus schkmcri 0 0 4.8 0 0 0 t 0 2.5 0 0 t flupda spp. t i 1 0' 0 t' 1A t t 1.5 1.0
.I cmbum fragile lA t 0 0 0 0 t t t 3.8 13 t Cryptanda pall.niana 1.2 6I t t t 0 1.2 t t 1.9 1.9 3.5 Diatona 0 t t I t i 1.5 t t 0 0 t
//ahchondria spp. 0 0 t 0 0 0 0 0 t 0 t 1.1 f.aminaria saccharina 0 0 1 2.2 2.4 23 0 t t 0 0 0 Alolpda app. O t 1.1 0 0 0- 0 -0 t 0 0 t Scninprella crrata 2.0 1.8 t- 0 0 0 t I i 3.8 ' 5.8 t Total 46 7.9 7.7 4A 13.5 21.3 4.1 233 29.0 11.0 9.0 20.1
- Percentage or coverage was < t% during the exptmure period.
6 i The lilack Point alte was not sampled prior to May 1985. . During 3. unit operation, the combined coverage substantially during the 3-unit period. Coverages l' of fotders decreased at EF and GN, due primarily of Alcyonidium spp., Mytilus edulis, and Tubularia to reduced covers of barnacles (Balanus impravisus crocca remained below 1%during3 unit operation, < and B. churncus at EF and B. crenatus at GN) but during 2 unit operation, high coverages tanged j relative to values observed during the 2 unit between 4-17% In addition, the percentages of period. At FI, covers increased during 3. unit cover for B. improvisus ranged from 3 to 21% operation, because of the increased abundances of during 2-unit operation, but remained below 3% q Cryptosula pallasiona, B. crenatus and B. during 3-unit opcration. . j balanoides. Fouling nt WP, FI, BP and GN has - been generally consistent over the operational . In terms of counts of individuals per panel, the periods, with only C. pal /asiana and S. errata dominant surface foulers were barnacles (Balanus ; showing increased abundance during 3. unit balanoides, B. crenatus, B. eburneus, B. improvisus, operation, while abundance of Batiy//us schlosseri ) decreased. At EF, nssemblages of foulers changed 1 1 Marine Woodborers 227
sites, and the highest abundances (>200!pancl)
= rew. it occurred at FI, BP and WP.
E' ): L 3-a P d Abundances of fouling organisms showed site. I ! ram A:;M$ !kd specific changes between the 3-unit and 2 unit periods. At EF, barnacles and mussels were 1 generally less abundant during the 3-unit than the im. ,,,,,gno 2 unit period. At FI, abundances of Afyritus edulis e [' , and Balanus crenatus were generally higher during [a g! *d* h . the 3 unit period. The WP site generally had g 7.fht M EE.llB._ higher numbers of Balanus juveniles during the 3-
. unit period. At GN, abundances of barnacles and $ mussels were not significantly different_ (P<0.05)
{ im. oye, pg between _the two operational periods.. 1i'ood boring Species l u. W Wood boring species in the Millstone Point !
$ vicinity include the molluscs Terrdo navalis and T.
lE
* 'l ws.ie r< nt bartschi, the isopods Lim,mria spp... and the
.o p amphipod Chelura ~ terebrans. Execpt ior T.
g' o-g- bortschi, which has been collected only at EF, and C. terrbrans, which has never been collected at EF, j these species were found at all sampling sites ! during both the 3-unit and 2-unit operational l c.onis no periods. a [ l Tersdo navalis. During 1988-89, T. navalis was 1 most abundant in May-Nov and Aug Feb (Table
. o i . . I . n. vn o . .! !.o! .i ~s enn.. . .o .i.~en..
n '. 3). Over all sites, abundances of T. navalis were r u-ne a F no-wu a F ... w a e ,a- ,a higher at WP and GN than other sites (Fig. 6), j The FI, BP and EF sites had low abundances of T. y 2-unrr g 3-UNn ge navalis during the 1988-89 sampling 1 period. I;g. 5. Average percentage of cover tot sessile (ouhng During the 3 unit period, average abundance of T. g] organisms. twe and dead comptments comtuned. on exposure navalis at WP in May.Nov (138.6) was significantly j panei cunected tun 1979 1969. ' higher (P<0.05) than that obtained during the 2 unit period (65.7).. This difference was principally due to the very high values obtained in 1986 .l Balanus juveniles) and the blue mussel (Afytilus ( > 300/ panel), while other 3-unit years (1987-1988) edulis) (Table 2). Balanus balanoides and B. were similar to 2-unit years (1979-1981). churneus were most abundant in the Feb-Aug Abundances in Feb.Aug were significantly lower exposute period and B, crrnatus in the Nov-May during 3 unit operation at WP (10.o vs. 33.3) and ! exposure period. Balanus improvisus was present GN (4.6 vt 118.6). Significant decreases were also . ! on panels throughout the year with highest found May Nov at EF (4.3 vs. 9.6) and GN (75.8 l abundances occurring on the Feb-Aug and Aug- vs. 236.1) for 3 unit versus 2-unit operating Feb panels. Balanus juvcolles (<2 mm) were most conditions. ' abundant in the Nov May exposure ' period, i corresponding with the peak abundance for B. ; crenarus. Abundance of Afytilus edulis was variabic ! among years and exposure periods. In 1988-89, mussels were most abundant in Aug Feb at all 228 Monitoring Studies,1989 l i i
TAllLl!1 Average density get panel (30 6 in') for barnacles and inussets during the current sainpling year (1989,it. Novemtwr 1988 through August 1989), during 3. unit (3-U) operation and during 2-unit (2.U) operation. SPECll3 STIE 12POSURi! PERIOD Aug Feb Nov-May Feb Aug May Nov 89 30 2U 89' 3U 2U 89 30 2.U 88 3U 2U Balanas amplihrhc CF 0 ta 11 0 0 0 0 t t t t 0 l'l 0 0 0 0 0 0 0 0 3 0 0 t ilP t i 1 0 0 0 0 1 --* O 2 - WP O I 9 0 0 1 0 t 15 0 l~ t GN O t t 0 0 0 0 0 12 0 0 0 ffalanus balanoides IT 0 0 0 0 0 0 0 0 0 0 0- 0 l'I O O O O O O t 193 0 0 0 0 IIP Q 0 0 0 0 0 20 240 -- 0 0 0 WP 0 0 0 0 0 0 4 3 0 0 0 0 GN 0 0 0 0 0 0 0 25 0 0 0 0 flalanar crrnatur IT U t 9 t 43 56 0 t 0 0 0 0 1 71 26 11 3 354- 660 435 t 148' 13 0 t t . 11P 0 0 0 52 53' 280 4 165 - 0 21 .. WP t t i 17 231 111 5 342 73 0 0 0 GN 19 6 t 7 69 236 114 101 0 0 t flalannt ebwn<ns liF 0 1 8 0 0 0 23 7' 10 t 3' 22 FI o O O o 0 0 to 2 t 0 t t ilP 15 6 0 0 0 0 7 6 -- 4 3 .. WP O O t 0 0' 0 t t- 26 0 t 8 GN O O o 0 0 0 0 t 3 0 .0 5-Italanar snprovitut EF 0 9 232 0 l' 16 19 8' ' 64 2 6' 65 FI 8 7 7 i t i 39 10 1 2 5 0 l IIP 37 13 2 0 0 0 4 6 -- 10 5 - WP 1 1 32 2 i t 0 t 23 0 0 4 GN 7 3 1 0- 0 0 t t 6 2 3 flalanut juveniles EF 0 t 59 3 59' 8 65 55' 0 126 10' 106 12 1 269 129 87 1581 902 761 21 16 9 2' 1 10 IIP 3 I t 440 1027 820 16 31 -- 0 0 - WP 11 5' 29 1122 1332' 562 t 47 308 0 0 11 i GN 209 77 96 194 1081- 722 0~ 42 45 t t 19 Myrdat edulu EF 2 5 169 0 53 129 0 0 0 -0 0 0 - I FI 2M 94 1 76 38' 7 t 5 t 0 0 0 i IIP 908 320 0 87 36 22 I i -- 0 0 - WP 660 220 150 23 26 26 3 2 9 0 0 2 1 l GN 3 1 4 1 1 3 0 t 22 0 0 0 '
" Density was less than one per lwiel, i ',The 111ack Point site was not sampled prior to May 19S5. (
Significant difference (P<0.05) between 3 unit and 2 unit densities, accordmg to a Wilcoxon signed rank test. l Marine Woodborers 229 I i
TAllLI13. Average dcashy of 7ctrdo twvalis in exlvisure pancia collecidd during the current samphng year (89,i.e, November 1988 - August 1989). during 3. Unit (3-U) oleration and during 2.Uait (2 0) operation... Spill- EXPOSURE PERIOD , Aug.l'eb Nov.May FetwAug May Nw 89 - 3.U 2U 89 3-U . 20. 89 3-U 2-U 88 3.U ~ 2.U IT mean cv a 13 11 3 83 0.2 0.1 0.1 1.2 0.6 . .1.5 - 5.0 43,- - 9.6 - 41.8 3A 4 231 200 0 IMO imo 561 358 24) 37.6 218 ' 155 FI mean - - cv 5.0 5.1 9.5 0.0 - 0.0 00 0.0 0.1 15.4 3.7 13.5 13.5 13 7 IAS 20 2 ? . . - 60.2. -320 29.6 ' ~263; '
--147 ItP mean .
cc 5.0 5.0 63 00 0.0 0.0 00 0.2 . 123 . 21.5 .- 7.3 167: 27,6 . . , . 325 108 - 19.5 -- -- WP mean , , cv 393- 29.6 37.3 0.0 0.0 - 0.0 1.0 10 6 333 - 593 ' 138 6. ..= 65.7 - i 9.5 11.4 2&7 , . (A3 39.3 - 32.2 &l' 20 7 220 ON mean , cv 49.$ 41.0 14 0 0.0 0.0 0.0 1.0 44 118.6 33.2 - 75.8, ^211' 69 121 3Q1 . . . - 51.6 313 163 133 . 19.4 9.2
*Coetricient of variaNhty (standard error of the mean, dwided by the mean and muluplied by 100). 9 ,Sipiricant dirterence between 3. unit and 2. unit densitics P(0,05), according to a Wilemon egned rank test. *cv could not be calculated because the mean was teru. 'lliack Point site was not sampled prior to May 1985.
TABLE 4. Average density of Tcredo baruchi in exixmure pancis collected during the current sampling yeah (89. i.e., November 1988 i August 1989). dunng 3. Unit (3.U) operation and during 2. Unit (2,U) operation. STIE EXPOSURE PERIOD Aug Feb Nov.May . - Fet>Aug . May.Nov 89 30 2.U 89 30 2.U - 89 3.U 2.U ' 88 ' 3U 2.U
~ ~
EF mean 30.5 149 / 14.0 - l.8 1.8 -. l0.0 0.0 ' ' 13.0*- 1.2 105.0 (178.9' < 10.0 c/ 402 l&8 3&l ' $1.6 ~ 35V ? , . 3,t 0 ^ 3&6 _364 144 - 343
", Coefficient of variabihty (standard error of the mean. dwided ty the mean and multiphed by 100). ..
SigmGcant dillerence between 3. unit and 2. unit densities (P<0 05), accordmg to a Wilcmon signed rank test.
*cv could not be calculated because the mean was zero.
Temla burlschi, As in all previous years, this 5). Linmoria abundances were lowest during ug- , shipworm was collected only at EP (Fig. 6). Feb at all sites and ranged from none to 58 per Abundances during 198849 continued to be highly panel. seasonal, ranging from none (Feb-Aug) to 105 , . 7 organisms (May Nov)-(Table 4). During 3-unit Several comparisons of Linmoria abundances for e operation, densities of T. tiartschi Lat' EF were 3 unit versus 2. unit . cxposureL l periods .wcre higher than 2. unit values in three ' exposure significantly different (P<0.05), although no trends periods; Aug Feb (149.4 vs 14.0), Feb Aug (13.0 were evident over all sites or exposure periods . 4 vs.1.2), May Nov (178.9 vs.10.0). (Table 5). ' Abundances have been greater during ' 3 unit operation in May Nov at GN, Nov-May at d Limnoria spp. - Annual abundances of Linmoria WP and Feb Aug at EF; abundances were lower in 4 were highest at WP~ and GN, low -at EF, and Aug Feb and Feb Aug at F1 and GN, and lower in . intermediate at F1 and DP (Fig. 8). Abundances in - Feb Aug and May-Nov at WP,- 1988 89 were highest in May Nov at all sites but EF, and ranged from 114 to 600 per panel (Table 1 230 Monitoring Studies,1989
L s > e
,Q rown' 2 C * "8 am 2mo iw t s00
,w s ono.
Ay} SW< o .an .. __r - - e -- d rw
$ Foa. blond a $
W auc; fos hiond I tW. Q tMo $
" ico a icoe h$m m
P _ rw = m h $. .n . ,v a . _ - - - - N e a h
- rw s' FuockPomt c5 g 2ow
$ Biock Point -I iso. g isoo ,
tcc Q (006,
$n , a eo o g m --- ? a 2,
3 > C ' d @ White Point White P(ant'
> zw *1 w 2ow n ISO p$$
rou
$ 1500 m p ,cco
$ A b - REIL . __ i .___t M R!kh.,.
zw Giants Neck PP f$ Cients Neck - IM s 9 :wo sco
$$$ 1500 p;$ iow p
$ .. -c E N . M CC "o' f_ - M31 _ M_.rP_
$$!$iEI $$$$Ie! SI$$$$$ o$$$ES!! $ II!$$! $$$$$$$$ $!$!!!! $$$$$$$
F auc-rie-t F eto-aoc a o mv-nov a > ov-mv a F auc-rea a F res-auc a . F uav-wov a F nav-mav a y 2-UNii g 3-UN!i g 40 0ZERO g 2 UNIT E 3-UNIT g<100; 'OZERO Fig. 6. Average numerical abundance of the shipworm, Tercdo Fig. 8. Average numencal abundance of the isopods, Linmoria it.nulis,in expuure pancis collected during 1979 1939. spp., in exposure panels collected 1979 1989. rfhuent Chclura terebrans. Abundances of Chelura - (2w lE terebrans,. collected in exposure pancis, . are
$ f_ _ _._ m .,...r. ..
presented in Figure 9 and Table 6. During 1988-j$tll?!i ?!?2l?ll ?!?!!?!! !!?!!!!! 89, this organism continued to be most abundant - -( r auc-no a e us.auc 4 F =<-* 4 > e a' 4 at GN (34.8/panet) and WP (77.3/pancl) in 'the May Nov exposure period. At all other sites and g2-UNif g3-UNIT g CO OZERO periods. densities WCrc <3/ panel. During 3 unit Fig. 7. Average numerical abundance of the shipworm, Tercdo operation, densitics have been significantly lower , i barucht in expmure pmels collected dunng 1979 1989. (P<0.05) than durinS 2-unit oEcration at WP and GN. Chelura terebrans has never been collected at EF, and average abundances at F1 and BP have never exceeded 1 per panel. Marine Woodborers' 231
% T ' ~
* ~ ' ' ' '
f~ 4
, 1 +
y _ i ' q 4 I L
. TABLE 5. - Average demity of thwude w in espmure panels collected during the curivat sampling year (89,i.e., Nowmtwr 1988
( 3 August 1989), during 3 Unit (3.U) operation and during 2. Unit (2 0) operation. ! l
. Sr111; . ,
. : EXPOSURE PERIOD
*- . iAugfeb . Nw44ay L Feb Aug ; May.Nw 5 89 ' 3.U - ' 2.U J 89 ' 30L 2UL 89' 3.U , : 2-U . 88i 3 0-. 20-j!
~
- sO mean l 0.0 12.8' 1.1 6.1 30 13 19.5 ' 66 0* ' -
2 9.0 '03~ 0.7 1.6 i
** :217- ' 258 L 612L 834 ' :;;
W . 3&7l 97.6 49.1 : 41.2 ; 3&l "27.9 L427
'j FI - mean f 0.0 : 2.9* J 26j ' 19 -
L' 2.0 03 J 36.5 : ! 193*' L127.9 ! 113.9- 89.8 ) E145.9 l cy - . 06 9 353 361 . 628 438 - 27.8 . ; 23 7 '26 0 39.6 > . .!R 7 - -!7.2 i- _ il 5 HP mean 0.0 8.0 : 3l0 7.8 ' '433' ~ 4.2 ' 40.8 94[8' .# E 167.4 ' [167.4 l J l cv . 421: Y1R2 31.8' '31 0 2R3 i3R2I i300i ' 34 0 I J 263 ~ l* r}}