ML20029C993
| ML20029C993 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 12/31/1993 |
| From: | Nichols R NORTHEAST UTILITIES SERVICE CO. |
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| NUDOCS 9405030186 | |
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{{#Wiki_filter:- . .. . .. Monitoring the Marine Environment of Long Island Sound at Millstone Nuclear Power Station, L Waterford, Connecticut Annual Report 1993
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Silverikle (Mealdia sp.) Curmer(Tautogalabras abpersus) J
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3 '. Aij ,le's.g l. ,4.og .L d <, b (.. American sand lance ymmodytes americasar) :
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- Winter Flounder (Pleuroneeses americamar)
- Tmaog (Tautoga onith) Grubby (Myoxocephalar aenaeus) l l
}' The picture on the cover depicts six fish genera common in Long Island Sound and in samples collected as part of the Millstone Nuclear Power Station fish ecology monitoring program. j j A- , - - . .
v l > Monitoring the Marine Environment of Long Island Sound at Millstone Nuclear Power Station, Waterford, Connecticut 1993 AnnualReport Prepared by: Staff of Nonheast Utilities Service Company . Environmental Services Division Aquatic Services Branch N U EnvironmentalLaboratory l Approved by: NE M*e Dr. Milan Keser
#J& dh/s Ronald C. Nichols April 1994
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. .ma We dedicate this repon to Dr. Linda E. Bireley, who recently took the position of Manager-Generation and Environmental Licensing, and who, for t!> past twenty years, had been involved with vinually every step in the development of the MNPS Environmental Monitoring Program.
ii Monitoring Studies,1993 i L_____________________._ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ ____
. _~ Acknowledgements This report was prepared by the staff of Northeast Utilities Service Company (NUSCO), Environmental Services Division, Aquatic Services Branch, located at N U Environmental Laboratory (NUEL), Millstone Nuclear Power Station, PO Box 128, Waterford, CT 06385. Staff members include: Dr. Milan Keser, Manager Ronald C. Nichols, Supervisor John A. Castleman David P. Colby Donald J.Danila Gregory C. Decker David G. Dodge James F. Foertch Christine P. Gauthier Raymond O. Heller Donald F. Landers Dr. Ernest Lorda J. Dale Miller Douglas E. Morgan John T. Swenarton Joseph M. Vozank Special appreciation is extended to the Environmental Programs Branch staff and our summer and intern staff
- (Kirsten Berg, Calli Conway, Paul Jacobson, Jr., Clay Livingston, Karen Main, Jessica Spelke, Kim Tuttle, Cynthia Walker, and Keith Wheeler) for their untiring efforts in field and laboratory support. Additional thanks to JoAnte K. DeRico, Richard A. Larsen and Henry R. Paul who no longer work for Aquatic Services Branch, but whose contributions to the monitoring program are gratefully acknowledged. Critical reviews of this report were provided by the following members of the Millstone Ecological Advisory Committec: Dr. John Tietjen (City ' University of New York), Dr. Nelson Marshall (emeritus, University of Rhode Island), Dr. Saul Salla (Professor emeritus, University of Rhode Island), Dr. William Pearcy (Oregon State University), Dr. Robert Wilce (University of Massachusetts), and Dr. Robert Whittatch (University of Connecticut).
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iv. Monitoring Studies 1993 e t t
Executive Summary Lobster Studies he mean carapace length of lobsters caught during 1993 (70.8 mm) was larger than previous 3-unit
'Ihe American lobster, Romarus americanus, is one values (69.5-70.2 mm), but within the range of of the most valuable species in the Connecticut values reponed in 2-unit study years. Only 3.3% of fishing industry. Between 0.8 and 2.7 million the catch was of legal-size during 1993, within the pounds have been landed annually since 1978 yielding range of 3-unit years but below the range of 2-unit between 2.4 and 8.4 million dollars to lobstennen years (5.9-9.1%). Percentage of females carrying employed in the fishery. Lobsters are highly extental eggs (berried) during 1993 was 12.2% and exploited throughout their range; in the Connecticut higher than in any previous study year (3.1 12.1%). ,
lobster fishery, more than 90% of legal-sized lobsters Berried females were, however, smaller during 3-unit are harvested each year. New fishery regulations have years (76.5 mm) than during 2-unit years (79.4 mm), been implemented throughout the lobster range to reflecting-the high proportion (90%) of berried reduce the high fishing mortality rates and to increase females below the minimum legal size of 82.6 mm. lamti production and subsequent recruitment. Since The most imponant factor regulating molting and 1984, Connecticut lobstermen have been required to growth of lobsters is water temperature. Water install escape vents in traps; the escape vents allow temperatures during the 3-unit study years were, on sublegal-sized lobsters to escape from traps and average, slightly warmer than during 2-unit study thereby reduce injury and mortality to this ponion of years. As a result, the peak in catches of molting the population. The minimum legal size (carapace lobsters in 3-unit years occurred earher (by 9 days) : length) of lobster was gradually increased in than during 2-unit years. Lobster growth per molt, as I 3 Connecticut from 81.0 mm (3 /16 in)in 1988 to determined by tag and recapture studies, averaged I 82.6 mm (3 h in) in 1990. Because of the regional 13.7% for both males and females in 3-unit st.udies, economic imponance of lobsters, the local population and was slightly higher than growth per molt of lobsters in the Millstone Point area have been observed during 2-unit studies (males 13.3% and sampled annually from May through October since females 13.0%). 1978 to determine if operation of Millstone Nuclear Results from tag and recapture studies indicate that Power Station (MNPS) has caused changes in local the overall percentage of recaptures in our traps was lobster abundance beyond those expected hem natural similar during 2- and 3-unit years (19% vs. 20%), , variability and high fishing mortality rates. Some whereas the percentage of recaptures by commercial ! changes were observed in abundance and pop 41ation lobstermen declined from 33% during 2 unit years to I characteristics of lobsters during 1993, but thy were 18% during 3-unit years. This decline of recaptures most likely related to high fishing levels and cranges in commercial traps was related to the 1984 escape in fishery regulations (escape vents, minimum legal vent regulation and not to MNPS operation. ! size increase) rather than to power plant impacts. Installation of escape vents, coupled with the fact that l The total number of lobsters caught and catch per most of om tagged lobsters are sublegal, resulted in unit effort (CPUE) of all sizes of lobster reached fewer tagged lobsters retained in commercial traps. record levels in 1992 and remained high during 1993. Conversely, our traps did not have escape vents and Total number caught (10,195) and CPUE (2.301) in retained similar numbers of tagged sublegal lobsters. I 1993 were the second highest reponed (previous Lobster tagging also indicated that local individuals ! ranges were 6,376-11,438 and 0.9N-2.457). While a are predominantly nonmigratory. Over 90% of the j significant increasing trend was observed in total tagged lobsters recaptured in commercial traps were CPUE from 1978 to the present, legal lobster catches caught within 5 km of Millstone Point. The average (those individuals 2 82.6 mm carapace length) have distance traveled by lobsters before they were caught significantly declined since the study began in 1978. in commercial pots was similar during 2- and 3-unit The CPUE oflegal-sized lobsters was 0.080 during years (2.4 vs. 2.9 km). Although a predominance of 1993 and within the range reported in previous 3-unit localized movement was observed in our study, a studies, but lower than the range reported during 2 number of lobsters (113) were reported caught j unit studies (0.098-0.173). outside LIS along the Rhode Island and M-husetts Executive Summary v i l l
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, i coasts, and in offshore deep water canyons on the edge Eelgrass population parameters (plant density, of the continental shelf. shoot length, standing stock biomass and percentage Since 1984, lobster larvae have been sampled from of reproductive shoots) and sedimentary characteristics May to August at the discharges of Units 1,2 or 3. (mean grain size, organic content and silt / clay The average density of larvae collected during 1993 percentage) measured in 1993 were generally within was 1.081 per 1000 m3 of cooling water, which was the ranges of previous years; the only exceptiens were the second highest value reported (previous ranges annual biomass at WP, whicis was the higtest yet were 3-unit 0.525-1.334; 2-unit 0.409 and 0.504). reported, and percentage of reproductive shoots at JC Estimages of total lobster larvae entrained through the and NR, which were also maxima.
plants cooling water system were based on sample The celgrass population at WP remains tmaffected density of larvae and total MNPS cooling water by MNPS operation, as population parameters have demand during the May to August hatching period. been generally stable since 1985. At NR, wide During 1993 an estimated 389,767 larvae were fluctuations of abundance have occurred, including entramed, within the range of previous 3-unit years localized elimination of plants from NR #1 (1986-(296,173-615,285), but higher than the 2-unit 87), from NR #2 (1987), and from NR #3 (1987-93). estimates of 77,458 and 128,550. Entrainmem These abundance fluctuations, however, are related to numbers have been substantially higher since Unit 3 factors other than MNPS operation because the began operating because the cooling water demand of Niantic River is not impacted by the thermal effluent. Unit 3 alone is about the same as that of Units 1 and Furthermore, in recent years NR #1 has been 2 combined. The potential impact of lobster larvae recolonized and the celgrass population has apparently entrainment is difficult to assess because of the recovered completely. At JC, changes in eelgrass uncertainty that exists concerning larval origin and abundance may be related to changes in water larval survival and recruitment rates to legal size. temperature, but, at least to date, these changes appear Since lobsters require 4-5 years of growth before they to be the result of natural variability rather than an are vulnerable to capture, and an additional 2 years of impact of 3-unit operation. growth to reach legal size, a decline in local lobster abundance caused by larval entrainment would not be Rocky Intertidal Studies apparent for several years. At present, fishery regulations implemented in Attached rocky shore communities, as described by 1984 (escape vents) and 1988 (increased minimum the NUSCO monitoring program, continue to serve size) to preserve the LIS lobster resource appear to be as effective integrators of local environmental effective. The percentage of berried females has conditions in the vicinity of MNPS. Conditions increased each year since the minimum legal size was resulting in much of the variability among firstincreased and lower incidence of claw loss and communities at sampling sites outside the influence reduced retention of sublegal sized lobsters in of MNPS were related to natural factors including site commercial traps were attributed to the use of escape orientation to prevailing wind-generated waves, the vents. However, fishing effort has more than doubled ability of available substratum (slope) to dissipate the since 1978 and funher increases may offset some of horizontal force of those waves, and the character of the benefits of the new regulations. that substratum (e.g., boulders, bedrock ledge, etc.). Community differences beyond those attributed to Eelgrass natural factors occu: red within the thermal plume area at sites located on Fox Island (FE and FN), and were Eelgrass is the predominant marine flowering plant directly attributed to MNPS operation. Various in estunnes and lagoons of temperate and warm boreal aspects of the impact-related community changes at coasts in the Atlantic and Pacific Oceans. In the Fox Island were identified through separate studies vicinity of Millstone Point, celgrass populations can which included qualitative algal sampling, estimation exhibit wide temporal and spatial variability in shoot of intertidal organism abundance, and studies of local length, plant density, standing stock biomass and Ascophyllum nodosum populations, other population parameters. During 1993, these Elevated temperature conditions caused by the 3 parameters were measured at three sites in the MNPS unit thermal plume allowed development of a unique area: Jordan Cove (JC), White Point (WP) and flora at FE. The most notable shifts in species occur-Niantic River (NR). rence, revealed by qualitative algal sampling, were the vi Monitoring Studies,1993
[ presence of wann water-tolerant species not typical of tinued to show evidence of sediment scour, and Jordan other sites (Agardhiella subulata, Gracilaria rikvahlac Cove (JC) sediment deposition. De intake site (IN) and Sargassumfilipendula), absence of common cold exhibited continued recovery from dredging activities water species (Mastocarpus stellatus, Dumontia near the intakes in the early 1980s, and Giants Neck contorta and Polysiphonia lanosa) and extended or (GN), as the control site, continued to show little reduced periods of occurrence of seasonal species with temporal variation and no effect of MNPS operation. warm or cold water affinities, respectively, he dominant taxa collected during 1993 at subtidal During 1993, power plant impacts on dominant stations included the polychaete species Aricidea species abundance patterns, caused by 2-cut water catherinae, Tharyx spp., Prionospio steenstrupi, circulation pattems and by 3-unit operations, were Polycirrus eximius,Scaletema tenuis,Protodorvillea observed only at FE, and were most pronounced in gaspeensis,Mediomastus ambiseta,Pygospio the low intertidal, where temperature conditions were elegans, the arthropods Ampelisca vadorum, A . most severe. He low intertidal community at FE, verrilli and Leptocheiruspinguis and representatives which prior to 1983 had been unimpacted and of the class Oligochaeta. The top four ranked taxa at characterized by perennial populations of Fucus, each station in 1993 accounted for 50% or more of all Chondrus and Ascophyllum and predictable seasonal individuals. In most cases, these organisms have peaks in bamacle abundance, has been replaced by a been the dominant subtidal taxa in both 2-unit and 3-persistent community dominated by Codium, Ulva, unit operational periods, Most stations were Enteromorpha and Polysiphonia. Also, populations characterized by one or more clearly dominant taxon of species observed in undisturbed transects only at (oligochaetes at EF, GN and JC, Aricidea carherinac FE (Sargassum. Gracilaria) persisted during 1993, at GN and JC and Tharyx spp. at GN) during both Ascophyllum populations at three stations in the operational periods. There has been no single domin-vicinity of MNPS continued to be monitored in ant taxon at IN during either operational period, where 1993. Elevated temperatures (2 3*C above ambient) mean relative abundance of any single taxon rarely at our station nearest the discharge (FN) caused exceeded 10% Analyses of local benthic commun-Ascophyllum to grow longer and more rapidly at this ities have identified changes and long-term trends in site, relative to stations farther away. A moderate community parameters, and have pennitted distinction level of growth enhancement was observed at FN between changes related to natural variability, and during 1992-93, when compared to previous years, those caused by power plant operation. attributed to lessened thermal plume incursion resuhing from an extended outage of Unit 2 for much Marine Woodborer Study of the peak growing season. As in previous years, Ascophyllum mortality, or loss of tagged plants and The Marine Woodborer Study report describes the tips, at our present sampling sites was not related to local distribution of Teredo bartschi, a semitropical proximity to the power plant but rather to degree of shipworm common from Texas to South Carolina, exposure to prevailing winds and waves. but capable of establishing isolated populations near thermal discharges in more northern climates. T. Benthic Infauna bartschi remains in MNPS discharge waters and, in 1993, it was collected for the first time in panels 500 During 1993, infaunal communities inhabiting m from the quarry cuts. Reduced currents around the i soft-bottom subtidal habitats in the vicinity of rock outcroppings at this new site may trap discharge l MNPS were sampled quarterly as part of a long-tenn water and increase the probability of collecting this l monitoring program. Dese communities were charac- immigrant species. The absence of T. bartschi at EF l terized in terms of species composition, abundance, in 1993 is probably related to unusual conditions ! and sedimentary parameters in order to identify spitial resulting from Unit 3 being off-line from i ugust to l and temporal patterns in community structure and to November, during the p'ak recruitment period for this I assess whether observed changes can be attributed to species. The distribution of T. bartschi remains ! construction or operation of the power plant. closely associated with the discharge waters of I Changes in sediments resulting from Unit 3 MNPS, suggesting that the discharge population has construction and initial operation events have resulted not adapted to ambient temperature conditions at i in alterations to associated infaunal communities in White Point,1700 m from the quarry cuts. Even recent years. During 1993, the effluent site (EF) con- though the current program represents a large l Executive Summary vii 1
reduction in sampling effort relative to previous study above the two-unit annual averages. The catches of years, it continues to effectively monitor the Atlantic and inland silversides in seines were all abundance of T. bartscht in the Millstone area. within historic ranges and above the two-unit period average, except for Atlantic silversides at JC. The Fish Ecology Studies grubby is unique because unlike the other potentially impacted fishes it experiences no fishing pressure. Studies of fish assemblages inhabiting the area Both larval and adult grubby abundance indices have amund MNPS were conducted to determine the effects been stable throughout the 17 years of monitoring. of station operations. These effects have been defined Tautog has been the second-most abundant egg taxon as power-plant related changes in the occunence, entrained and has accounted for more than 30% of the distribution and abundance of fish species which total eggs collected since 1979. The tautog egg would affect the community structure. Fish entrainment estimate for this report year was the assemblages could be adversely affected by losses due lowest since three-unit operation began and the to impingement of juvenile and adult fish on the average density of eggs at the entrainment site (EN) intake screens, entrainment of fish eggs and larvae was the second lowest since sampling began. Larval through the cooling water system or by changes in tautog average densities at EN were within their thermal regime or physical habitats. historic range. He cunner egg entrainment estimate Trawl, seine and ichthyoplankton monitoring also was the lowest since Unit 3 began operating. programs were established in 1976 to determine the Cunner larval densities were within their historic impact of MNPS on local fish assemblages. Of the range. Prior to 1992-93, the trawl catch of cunner 120 different fish taxa that have been collected since had been decreasing at all six stations. This year's then in these programs, seven taxa (American sand trawl catches were below the two-unit operational lance, anchovy, grubby, silversides, tautog, cunner catches at two inshore stations, but were at a historic and winter flounder) have been identified as having the high in Niantic Bay. Both tautog and cunner potential to be impacted by MNPS either by young-of the year have accounted for a high entrainment or because of their susceptibility to proportion of the fish caught in the trawl since three- i thermalimpacts. unit operation began. Abundance data were analyzed separately for two- Because over 85% of the eggs entrained at MNPS unit (1976-1985) and three-unit (1986-1992) were tautog and cunner eggs, special studies were operational periods and for the entire 17 year data conducted in 1993 to determine the entrainment series (both periods combined) to determine if changes mortality of these. eggs. He average hatching rate in fish abundance have occurred. Larvae of sand lance was 4%. To examine daily fluctuations of egg and anchovy have declined as have adult tautog and abundance, samples were collected every two hours cunner. Because so many factors affect the abundance during three 24-hour periods. Examination of the of these taxa the reasons for these declines are difficult geometric mean for each 2-hour sampling period to ascertain. Arr.erican sand lance larvae has ranked showed that on the average, daily peak spawning for third among fish larvac entrained and it has cunner and tautog occurred at about 1800 hours and significantly decreased in abundance in the entrain- then declined rapidly. Estimated mortality rate ment and offshore samples. The bay anchovy is during this rapid decline was 44% per hour for cunner typically the most abundant ichthyoplankton species and 47% per hour for tautog. These very high egg collected in estuaries within its range and it was the mortality rates may account for the low numbers of dominant larval taxa entrained at MNPS. Similar to cunner and tautog larvae collected compared to the the sand lance, this fish also exhibits large natural large number of eggs of these two fishes, abundance fluctuations. Along the Connecticut coast, the Atlantic silverside and the inland silverside are Winter Flounder Studies among the most common shore zone species. Typical of short-lived species, the catches of Atlantic The local Niantic River population of the winter silverside by trawl and seine were highly vanable and flounder (Pleuronecresamericanua) is potentially annual catch indices ranged over two orders of affected by the operation of MNPS, particularly by magnitude. De trawl CPUE of Atlantic silvenides entrainment of larvae through the cooling-water was at a 17-year high at the two Niantic Bay Stations systems of the units. As a result, intensive studies of (NB and IN), and all 1992-93 trawl catches were the life history and population dynamics of this viii Monitoring Studies,1993
valuable sport and commercial species have been declined about 90% during this stage in 1993. His undertaken since 1976. stage may include a
- critical period". for winter The median trawl catch-per-unit-effort (CPUE) of flounder as' survival rates genstally improve fish larger than 15 cm collected in the Niantic River p ogressively for larger size-classes.
during the February-April 1993 spawning season was Yot ng-of-the-year winter flounder have been 1.9. His value was only about 30% of the CPUE of collected during late spring and summer in the Niantic 6.2 for last year, and it was the smallest CPUE in the River since 1983 and in Niantic Bsy since 1988. In 18-year time-series. The Jolly stochastic model was 1993, abundance of newly metamorphosed young was used with mark and recapture data to estimate the relatively low, particularly in the Niantic River. absolute abundance of the adult spawning population Mortality was once again apparently quite high in the (all winter flounder larger than 20 cm, which includes bay, with no fish caught there by mid-summer. Late-some immature fish). The most recent abundance season median densities at two stations in the river estimate of 12,178 fish fcr 1992 was only 19% of the were among the lowest found since 1983. 1991 estimate and further illustrated the severe decline An index of abundance was calculated for young-of-of winter flounder abundance in recent years. the-year fish taken during the late fall and early winter Each year, about one-third to one-half of the winter at the trawl monitoring program stations. The 1992-flounder found in the Niantic River during the 93 abundance index (1992 year-class) was 31.1, the spawning period have been mature females. Using highest in the 17-year series. This was consistent available information on sex, age, and size with the high abundance of these fish found during composition, the annual female winter flounder the summer of 1992 and was indicative of the parental stock sizes have been estimated for the past strength of the 1992 year-class. However, relatively 17 years. These estimates have ranged from 7,821 few of these fish were taken within the Niantic River (1993) to 78,629 (1982) fish, with corresponding during the adult spawning population surveys in early total egg deposidon ranging from about 6.4 (1993) to 1993. Young-of-the year abundance indices were not 45.6 billion (1982). significantly correlated with those for age-4 and 5 Estimates of larval winter flounder abundance at the female adult spawners. herefore, none of the early MNpS discharge (entrainment sampling) have been life stages could be used as a reliable index of year-obtained since 1976, at a station in mid Niantic Bay class strength for Niantic River winter flounder stock. since 1979, at three stations in the Niantic River Egg production estimates from annual spawning since 1983, and at the mouth of the Niantic River surveys were scaled to numbers of spawning females during 1991-93. He low abundance of newly-hatched and used as recruitment indices. These indices larvae in Niantic Bay compared to the Niantic River together with adult female spawning stock estimates suggested that most local spawning occurred in the and mean annual February water temperatures were river. Larval abundance in 1993 was the lowest in used to fit a three-parameter Ricker stock-recruitment both the Niantic Bay and River since sampling began relationship (SRR). Additionally, the indirect esti-in 1976 and 1983, respectively. Annual larval mate of the winter flounder theoretical rate of increase ; abundances in the bay for 1976-93 appeared to reflect (the SRR a parameter) derived by the Connecticut ! region wide trends, because they were highly Department of Environmental Protection (DEP) was correlated to abundance indices in Mount Hope Bay, used for modeling the dynamics of the winter flounder i MA and RI. population for impact assessment purposes. The Larval developmental stage and length were closely value of a, re-scaled to units of fish numbers from related. Smaller larval size-classes predominated in biomass units, was estimated as 5.42 and described the river and larger size-classes were more prevalent in the inherent potential for increase of the Niantic River ; the bay. In Niantic Bay, growth and development winter flounder stock. De estimate of (the second I were correlated with water temperature, and in the SRR parameter), which describes the annual rate of l river growth appeared to be related to both water compensatory mortality as a function of stock size, { temperature (positively) and larval density has shown little annual variation since 1988. He : (negatively). Estimated mortality of larvae in the third and last parameter in the SRR described a l Niantic River for 1984-93 ranged from about 82 to negative relationship between winter flounder recruit- l 98E Mortality was consistently highest during ment and water temperatures in February, the month I Stage 2 of developrnent (3- to 4-mm size-classes), when most spawning, egg incubation, and hatching which is when feeding first occurs; larval abundance occur. Executive Summary in l l
4 . The number of larvae entrained through the calculations. All SPDM runs were stochastic and con-condenser cooling-water system at MNPS is the most sisted of 100 Monte Carlo replicates for each yearly direct measure of potential impact on winter flounder. stock projection over a 100 year period (1960 2060). Annual estimates of entrainment were related to larval An initial stock size of 97,075 lbs was used to densities in Niantic Bay, as well as to plant opera- represent the theoretical (no fishing assumed) tion. The entrainment estimate for 1993 of 41.1 maximum spawning potential (MSP) of the Niantic million was the lowest since three-unit operation River female spawning stock. When fishing effects began in 1986 and was one of the lowest in the 18 were simulated, the annual projections of the initially year series. Low entrainment was attributed to low unfished stock become the baseline time series of larval abundance, as all MNPS units operated annual spawning biomass for Niantic River winter throughout much of the larval winter flounder season flounder subjected to fishing, but in the absence of during 1993, any plant impact. Under the exploitation rates The irupact of larval entrainmer ; on the Niantic simulated, the stochastic mean stock size of the River stock depends upon the fraction of its produc- baseline declined to about 48,300 lbs in 1971 and to tion that is entrained each year. Empirical mass- 12,300 lbs in 1993. "Ihe latter value was about one-balance calculations for 1984 93 indicated that a large half of a generally accepted critical stock size, dermed number of entrained larvae came from areas of Long as 25% of MSP. Following simulated reductions in Island Sound other than the Niantic River. An esti- fishing, however, the stock rapidly recovered. A new mated 11 to 35% of the larvae entrained at MNPS series of stock size projections were then simulated appeared to have originated from the Niantic River dur- by adding the effect of larval entrainment at MNPS. ing these years. Percentages of the river production The lowest projected stock biomass under that were entrained annually ranged from about 4 to simultaneous fishing and effects of MNPS occurred in 21% and the estimated fraction of Niantic River 1993 (10.600 lbs), whereas the greatest absolute winter flounder production that would be entrained decline relative to the baseline occurred in 2001 (a under full (100% capacity) three-unit operation ranged difference of 7,800 lbs). Generr.lly, however, greater from about 5 to 24%. reductions in stock biomass resulted from fishing A computer simulation model (SPDM) was used than from larval entrainment, because fishing tends to for long-term assessments of MNPS impact. Input remove larger fish and reduce average weight of the data used by the model included basic life-table remaining spawners. The simulated spawning stock parameters, the three-parameters of the SRR, retumed to near baseline levels about 6 years after the February water temperature statistics, and simulation scheduled termination of Unit 3 operation in 2025. parameters specific to each model run, including a The probabilities that the Niantic River female random variability component. Conditional mortality spawning stock biomass would fall below selected rates corresporiding to postulated larval entrainment reference sizes (25,30, and 40% of MSP) were deter-and juvenile and adult impingement at MNPS were mined to help assess the long-term effects of MNPS simulated according to historical information and operation. A stock less than 25% of MSP is projections. Fishing mortality rates (F) were pro- considered overfished, whereas one thst is at 40% of vided by the DEP. Initially, F was set at 0.40 and MSP can maximize yield to the fisheries while remamed unchanged through the 1960s, increased grad- remaining stable. For both baseline and MNPS-ually to 0.62 by 1988 and thereafter more rapidly to a impact simulations, it was likely (p 2 0.87) that the maximum of 130 in 1991. Based on proposed regula- stocks were greater than 40% of MSP in 1970. At tory changes, F was projected to decrease substan- the lowest point of both stock projections in 1993, tially through the late 1990s, dropping to 0.50 by all replicates were less than 25% of MSP. Simulated 2001 and remaining unchanged through the rest of the reductions in fishing allowed for a rapid increase in simulated years. The winter flounder stock was spawner biomass and it was likely greater than 30% simulated as female spawner biomass (ibs), which is of MSP by 2010 ( p 2 0.97) and had a better than more dir .ctly related to reproductive potential than even (p = 0.56) chance of being greater than 40% of fish numbers. Annual rates of Niantic River winter MSP by 2020. These increases, however, assumed flounder larval entrainment were based on actual or that changes in fishing regulations would be estimated MNPS cooling-water flow and estimated or implemented as scheduled and that they would achieve projected entrainment as derived from mass-balance the expected reductions in fishing monality. x Monitoring Studies,1993
p *, Table Of Contents Acknowledgements .................................... iii Ex ecu ti v e S u m m a ry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v I n t ro d u c ti o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Lo b st er S t u d i es . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Ecigrass ........................................... 35 Rocky Intertidal Studies ................................. 51 B e n t hic In fa u n a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Marine Woodborer Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Fish Ecology St udies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 Winter Flounder Studies ................................141 I i.
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~l i
t f i s d htoring Studies,1993 t h e v-w--- ._________E__.__'_.
Introduction Reporting Requirements entitled " Docket No. 4, Certificate of Environmental Compatibility and Public Need for an Electric This repon summarizes results of ongoing environ. Generating Facility identified as ' Millstone Nuclear mental monitoring programs conducted by Nonheast Power Station, Unit 3,' located in the Town of Utilities Service Company (NUSCO) in relation to Waterford, Connecticut" and dated March 22,1974). the operation of the three-unit Millstone Nuclear This report satisfies the requirements of the NPDES Power Station (MNPS). MNPS can affect local permit and of the CSC by updating and summarizing marine biota in several ways: large organisms may be various studies conducted at MNPS that were irnpinged on the traveling screens that protect the presented rnost recently in NUSCO (1993). condenser cooling and service water pumps; smaller ones may be entrained through the condenser cooling- Siudy Area water system, which subjects them to various mechanical, thennat, and chemical effects; and marine MNPS is situated on Millstone Point, about 8 km communities in the discharge area may be subjected west-southwest of New London on the Connecticut to thermal, chemical, and mechanical effects resuhing shore of LIS (Fig.1). The propeny, covering an area from the outflow of the cooling water. In addition, of about 200 ha,is bounded to the west by Niantic occasional maintenance dredging is done in the Bac. to the cast by Jordan Cove, and to the south by vicinity of the intake structures. The basis for the Twotree Island Channel. The MNPS monitoring studies is the National Pollutant Discharge Elimin-programs sample a study area of approximately 50 ation System (NPDES) permit (CT0003263) issued km thnt extends from the northem portions of the by the Connecticut Depanment of Environmental Niai.'ic River and Jordan Cove to Giants Neck,2 km Protection on December 14, 1992 to Northeast south of Twotree Island, and 2 km east of White Nuclear Energy Company (NNECO), on whose Point. Work takes place from the shoreline into areas behalf NUSCO has undertaken this work. 'Ihe regu- as deep as 20 m southwest of Twotree Island. lations in the permit allow the MNPS cooling water Strong tidal currents predominate in the vicinity of to be discharged into Long Island Sound (LIS) in Millstone Point and influence the physical charac-accordance with Section 22a-430 of Chapter 446k of teristics of the area. Average tidal flow through Two-3 the Connecticut General Statutes and Section 301 of tree Island Channel is approximately 3,400 m sec'8 the Federal Clean Water Act, as amended. Paragraph and at maximum is about 8,500 m sec I (NUSCO
$ of the MNPS NPDES permit states that: 1983). Current velocities are about I to 1.8 knots in The permittee shall conduct or continue to conduct the channel, slightiy less (l to 1.5 knots) near the biological studies of the supplying and receiving plant and in Niantic Bay, and relatively weak in waters, entrainment studies, and intake impinge- Jordan Cove and in the upper Niantic River, The ment monitoring. The studies shallinclude studies curreats are driven by semi-diurnal tides that have a of intertidal and :ubsidal benthic communities, mean and maximum range of 0.8 and 1.0 m, finfish communities and entrained plankton and respectively. Thermal and salinity induced stratifi-shall include detailcJ studies oflobster populations cation may occur in regions unaffccted by strong tidal and winterflounderpopulations, currents. The greatest temperature variation has been in addition, paragraph 7 of the pennit requires that:' observed in nearshore areas where water temperature On or before April 30, 1993 and annually can vary from 3 to 25'C: salinity varies much less thereafter, submitfor review and approval of the and ranges from 26 to 30% The bottom is generally Commissioner a detailed report of the ongoing composed of fine to medium sand throughout the biological studies required by paragraph 5 and as area. but also includes some rock outcrops and muddy qpprowdunderparagraph 6. sand, especially near shore. Strong winds, panicu-Furthermore, a decision and order of the Connecticut larly from the southwest, can at times result in Siting Council (CSC) requires that NNECO inform locally heavy seas (up to 1.5 m or greater) near the Council of results of MNPS environmental Millstone Point. Additional information on local impact monitoring studies and any modifications hydrography and meteorology can be found in made to these studies (paragraph 6 of the proceeding NUSCO (1983).
Introduction 1
MNPS NY CT l
\
[e N lantic River 1 km o 1 mi i Niantle Bay MNPS g Jordan N Cove White Giants Point Seaside
. Neck I Twotree Island Channel Pobt k 0 Twotree Island Long Island Sound Badien Rest Fig.1. The area in which biological monitoring studies are being conducted to assess the effec % of :he operation of MNPS.
Millstone Nuclear Power Station plants from debris. Units 1 and 2 have always had 9.5-mm mesh traveling screens. Unit 3 originally De MNPS complex consists of three operating had 4.8-mm mesh screens, a combination of 9.5- and nuclear power units; a detailed description of the 4.8-mm mesh screens from early 1990 through station was given in NUSCO (1983). Unit 1, a 660- summer 1992, and only 9.5-mm mesh screens as of MWe boiling water reactor, began commercial August 15,1992. Fish return systems (sluiceways) operation on November 29,1970; Unit 2 is an 870- were installed at Unit 1 in December 1983 and at Unit MWe pressurized water reactor that began commercial 3 during its construction to return aquatic organisms operation in December 1975; and Unit 3 (1150-MWe washed off the traveling screens back to LIS. The pressurized water reactor) commenced commercial installation and operation of these sluiceways have operation on April 23,1986. All three units use minimized thc impact of impingement at MNPS once-through condenser cooling water systems with (NUSCO 1986,1988a). A chronology of significant rated circulating water flows of 26.5,34.6, and 56.6 events associated with MNPS construction and m3sec-1 for Units 1 through 3, respectively. operation, including installation of devices designed Cooling water is drawn from depths of about I m to mitigate environmental effects and unit operational below mean sea level by separate r.horeline intakes shutdowns exceeding 2 weeks, are found in Table 1. located on Niantic Bay (Fir 2). The intake Capacity factors (electricity produced as a percentage structures, typical of many coasta power plants, have of maximum possible production) during 1993 were coarse bar racks (6.4 cm on center, 5.1-cm gap) 92.8% for Unit 1,82.5% for Unit 2, and 65.0% for . preceding vertical traveling screens to protect the Unit 3. 2 Monitoring Studies,1993
TAB 121. Chronology of major construction and cgeration eventi at MNPS through 1993. Date Acdvity Reference
- December 1965 Construedon inidated for Unit I btSCO (1973)
Novtznber 1969 Construction initiated for Unit 2 began NUSCO (1973) October 26,1970 Unit 1 inidal crideality; prts!cced hrst thermal effluent DNGL Novemter 29,1970 Unit 1 initial phase to grid DNGL De<=mber 28,1970 Unit I began commercial operation DNGL January 15,1971 to Felsruary 22,1971 Unit I shutdown DNGL August December 1972 Surface boom at Unit 1 NUSCO (1978) November 1972 Fish barrierinstalled at quarry cut NUEL September 3,1972 to March 20,1973 Urut I shutdown DNGL Novemter 1972 Unit 2 cdfer dam removed hTSCO (1973) April 18 to July 28,1973 Urut 1 shutdown DNGL August-December 1973 Surface boom at Unit 1 NUSCO (1978) July-December 1974 Surface lumn at Unit 1 NUSCO (1978) Sepember I to November 5,1974 Unit I shutdown DNGL July-October 1975 Surface boom at Unit 1 NUSCO (1978) July 1975 Baiam boom installed at Unit i NUSCO (1978) August 5,1975 Unit 3 coffer dam construction began NUEL Septanber 10 to October 20,1975 Unit 1 shutdown DNGL Ocsober 7,1975 Unit 2 produced first effluent EDAN November 7,1975 Unit 2 inidal cridcality; produced fint thermal effluent EDAN November 13,1775 Unit 2 inidal phase to grid DNGL December 1975 Unit 2 began commercial cperadon NUEL March 19,1976 Unit 3 coffer dam construction fmished NUEL June 4ctober 1976 Surface boom at Unit 2 NUSCO (1978) Onober I to December 2,1976 Unit I shutdown DNGL December 20,1976 to January 20,1977 Unit 2 shutdown DNGL May 6 to June 25,1977 Unit 2 shutdown DNGL June 4ctober 1977 Surface boum at Unit 2 NUSCO (1978) November 20,1977 to May 1,1978 Unit 2 shutdows DNGL March 10 to April 15,1978 Unit I shutdown , DNGL March 10 to May 21,1979 Unit 2 shuswn DNGL Apra 28 to June 27,1979 Unit 1 shutdown DNGL August 10 to 25,1979 Umt 2 sho*wn DNGL Novernber I to December 5,1979 Unit 2 shutdown DNGL May 7 to June 19,1980 Unit 2 shutdown DNGL June I to June 18,1980 Unit I shutdown DNGL August 15 to October 19,1980 Unit 2 shutdown DNGL October 3,1980 to Jure 16,1981 Unit I shutdown DNGL January 2 to 19,1981 Urut 2 shutdown DNGL Decernber 5,1981 to March 15,1982 Urut 2 shutdcwn DNGL March 1981 Bottom bomn removed at Urdi I NUEL Scpember 10 to November 18,1982 Unit I shuidown DNGL March 2 to 18,1983 Unit 2 shutdown DNGL April September 1983 Unit 3 coffer darn rernoved, intake maintenance dredging NUEL May 28,1983 to January 12,1984 Unit 2 shutdown DNGL December 1983 Fish retum system installed at the Unit I intake NUEL August 19g3 Second quarry cut opened NUEL Apr013 toJune 29,1984 Unit I shueim DNGL Fet= vary 15 to July 4,1985 Unit 2 shuidown DNGL Jare 1985 Intake maintenance dredging NUEL Sepember 28 to Novemter 7,1985 Unit 2 staatdown DNGL Ocsot.cr 25 to December 22,1985 Unit I shutdown DNGL Novemtwr 1985 Unit 3 produced first effluent EDAN Fetruary 12,1986 Unit 3 produced first thermal efnuent EDAN April 23,1986 Unit 3 legan commercial cperadon DNGL i introduction 3
TABLE 1. (cont.). July 25 to August 17,1986 Unit 3 shutdown DNGL Sepernber 20 toIVe atnx !8,1986 Unit 2 shutdown DNGL December I to !!,1986 Unit I shutdown DNGL January 30 to Fe wuary 16,1987 Unit 2 shutdown DNGL March 14 to Apiil lo,1987 Unit 3 shutdown DNGL June 5 to Angust 17,1987 Unit 1 shutdowm DNGL November I,1987 to February 17.1988 Unit 3 shutdown DNGL December 31,1987 to February 20,1988 Unit 2 shutdown DNGL April 14 to May 1,1988 Unit 3 shutdown DNGL May 7-22,1988 Unit 2 shutdown DNGL October 23 to November 8,1988 Unit 3 shutdown DNGL February 4 to April 29,1989 Unit 2 shutdown DNGL April 8 toJune 4,1989 Unit I shutdown DNGL May 12 toJune 12,1989 Unit 3 shutdown DNGL October 21 to November 24,1989 Unit 2 shutdown DNGL March 30 to April 20,1990 Unit 3 shutdown;installadon of some 9.5 mm intake screen panels DNGL May 8 toJune 15,1990 Unit 2 shutdown DNGL September 14 to Nwember 9,1990 Unit 2 shutdown DNGL February 2 to April 17,1991 Unit 3 shutdown;installadon of new fish buckets and sprayers DNGL April 7 toSepernber 2,1991 Unit I shutdown DNGL Apri! 23 to May 11,1991 Unit 2 shutdown DNGL May 26 toJuly 7,1991 Unit 2 shutdown DNGL July 25,1991 to February 6,1992 Unit 3 shutdown; installadon of new fish buckets and sprayen DNGL August 7 to Sepember 11,1991 Unit 2 shutdown DNGL October 1,1991 to March 3,1992 Unit I shutdown MOSR November 6 to December 27,1991 Unit 2 shutdown MOSR January 28 to February 14,1992 Unit 2 shutdown MOSR March 22 to April 6,1992 Unit I shutdown MOSR May 16 toJune 4,1992 Unit 3 shutdowm; installation of new fish buckets and sprayers MOSR May 29,1992 to January 13,1993 Unit 2 shutdown MOSR July 4 to August 15,1992 Unit I shutdown MOSR August 15,1972 Completed installadon of new fish buckets and iprsyen at Unit 3 NUEL Sepember 30 to November 4,1992 Unit 3 shutdown MOSR July 31 to November 10,1993 Unit 3 shutdown MOSR Sepember 15 to October 10,1993 Unit 2 shutdown MOSR
- DNGL refers to the daily net generation log, NUEL to NUSCO Environmental Laboratory records, EDAN to the environmental data acquission network, and MOSR to the monthly nuclear plant operaung status report.
MNPS cooling water is nominally heated in Units m of the quarry the surface-oriented plume cools to 1,2, and 3 from ambient temperature to a maximum within 2.2*C above ambient Beyond this distance of 13.9,12.7, and 9.5'C, respectively. Each unit has the ' plume is highly dynamic and varies with tidal separate discharge structures that release the efflueni currents (Fig. 3). liydrothermal surveys conducted at into an abandoned granite quarry (ca. 3.5 ha surface MNPS were described in NUSCO (1988b). area, maximum depth of approximately 30 m). The thermal discharge (about ll*C warmer than ambient Monitoring Programs under typical thnse-unit operation) exits the quarry through two channels (cuts), whereupon the thermal This report contains a separate section for each effluent mixes with LIS water (Fig. 2). The cuts are major monitoring progra,1, some of which have been equipped with fish barriers consisting of 19-mm ugoing since 1968. These long-term studies have metal grates, which serve to keep larger fish out of prov3ded the representative data and scientific bases the quarry. ' The thermal plume is warmest in the necessary to assess potential biological impacts as a immediate vicinity of the cuts and within about 1,100 result of MNPS construction and operation. The sig-4 Monitoring Studies,1993
r l Millstone Nuclear i Unit 3 Power Station
, Jordan Cove 3 Unit 2 U intakes 2
- Unit 1 discharges 1 2 1
3 200 m o , quarry O l 0 N second cut original cut Niantic Bay Twotree Island Channel . Fig. 2 The MNPS site, showing the intake and discharge of each unit. the quany, and the two quarry discharge cuts, nificance of changes found for the various commun- report, ecological and hydrographic studies,1977. ities and populations beyond those that were expected Millstone Nuclear Power Station. to occur naturally were evaluated using best available NUSCO.1983. Millstone Nuclear Power Station methodologies. Programs discussed below include Unit 3 environmental report. Operating license Winter Flounder Studies, Lobster Studies, Fish stage. Vol.1-4. Ecology Studies, Benthic Infauna, Rocky Intertidal NUSCO.1986. The effectiveness of the Millstone Studies Marine Woodborer Studies, and Ec! grass. Unit I sluiceway in returning impinged organisms Reporting penods for each section vary and were pred- to Long Island Sound. Enclosure to Letter icated on biological considerations and processing D0ll85 dated May 27,1986 from R.A. Reckert, time necessary for samples, as well as on regulatory NUSCO, to S.J. Pac, Commissioner, CT DEP. requirements, in cases where the seasonal abundance 18 pp. of organisms differed from arbitrary annual reporting NUSCO.1988a. The effectiveness of the Millstone - periods, the periods chosen were adjusted to best Unit 3 fish return system. Appendix 1 to define the season ofinterest for a particular species or Enclosure 3 to Letter D01830 dated January 29, community. 1988 from EJ. Mroczka, NUSCO, to L. Carothers, Commissioner, CT DEP, 21 pp.- l References Cited NUSCO.1988b. Hydrothermal studies. Pages 323- -i 355 in Monitoring the marine environment of NUSCO. (Northeast Utilities Service Company). Long Island Sound at Millstone Nuclear Power 1973. Environmental effects of site preparation Station, Waterford, Connecticut. Three-unit and construction. Pages 4.4-1 to 4.51 in operational studies,1986-87. Millstone Nuclear Power Station, Unit 3, NUSCO.1993. Monitoring the marine environment Environmental report. Construction permit stage. of Long Island Sound at Millstone Nuclear Power l NUSCO.1978. Impingement studies. Millstone Station, Waterford, Connecticut. - Annual report Units 1 and 2,1977. Pages 1-1 to 4-2 in Annual 1992. 269 pp. l
. Introduction 5
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6 Monitoring Studies.1993
' < s 0 5000 ft N WPS Jordan Niantic Bay E Cove
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Lobster Studies I n t rod u c t io n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Ma t erials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... 11 Results and Discussion . . . . . . . . . . . . . . . . . . . .......................... 13 Te mpera t u re a nd Salin ity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Abundance and Catch-per-Unit-Effort ............................. 14 [ Population Charreteristics . . . . . . . . . . . ....... ................. . 16 l Size. Fre q u e n cy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 S ex R a t ios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Reproduction ..........................................20 Molting and Growth . . . . . . . . . . .......................... 21 l Cu ll s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 i Ta gg i n g Prog ra m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ........... 24 L M ove m e n t . . . . . . . . . . . . . . . . . . . . . . . ..... ....... .......... 25 l Entrainment ............ ......... ......................... 26 Conclusions . . . . . . . ...................... ....................... 28 References Cited . . .................... .......................... 29 ; 1 l 1 1 l i i i i i i I Lobster Studies 9 I
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Lobster Studies , , Introduction those expected from natural variabihty and the high rate of fishing. The potential impacts of The American lobster, Romarus americanus, is power plant operations on the local population of one of the most valuable species in the lobsters include entrainment of larval lobsters Connecticut fishing industry (Blake and Smith through the cooling water systems, impingement of 1984). Annual landings in Long Islano Sound juveniles and adults on the intake traveling (LIS) of 0.8 to 2.7 million pounds from 1978 to screens, and effects of the heated discharge. 1993 yielded between 2.4 and 8.4 million dollars to Entrainment and impingement ' contribute lobstermen employed in the fishcry (Smith et al. additional mortality to the locallobster population 1939; Connecticut Department of Environmental and thereby may alter recruitment patterns. Protection CT DEP, Marine Fishery Statistics). The objectives of the lobster program are to Nearly 30% of the total Connecticut landings evaluate year-to-year, seasonal, and among station during 1993 were made in New London county, changes in catch.per-unit effort, as well as which includes the Millstone Point area. population characteristics such as size frequency, Lobsters are highly exploited throughout their growth rate, sex ratios, female size at sexual range and overfishing could impact recruitment maturity, characteristics of egg. bearing females, and lead to a decline in abundance of coastal and lobster movements. Additionally, since 1984, populations (Anthony and Caddy 1980). To studies have been conducted during the hatching address the high fishing mortality rates, and to season to estimate the nurnber of lobster larvae improve larval production and subsequent entrained through cooling water systems. Impacts recruitment, the New England Fishery associated with plant operations on the local Management Council (NEFMC) recommended an lobster population were assessed by comparing increase of minimum legal size of lobsters in results of the_1993 study to _ther o 3. unit lobster producing states. In Connecticut, new operational study years (1986-1992) and to data lobster fishery regulations were implemented collected during 2. unit operations -(1978-1985). beginning in 1988, which increased the minimum Results from the 2 unit period were also compared. legal size (carapace length) from 81.0 mm (3 % to combined 3 unit operational data (1986-1993) to in) to 81.8 mm in 1989 (3 '/y in) and to 82.6 mm . assess impacts associated with the addition of (3 % in) in 1990. Increases in minimum legal size Millstone Unit 3. When appropriate, results of should eventually improve yield per recruit, unless our lobster study were compared to other studies an escalation of fishing effort offsets the benefits of conducted in LIS and throughout the range of the raising the minimum size. In 1992, while fishing American lobster, effort continued to rise, landings in the United States and Canada substantially declined (down MaterinIs and Methods 13% and 20%, respectively) prompting further management action by the NEFMC. The Council Full description of methods used to conduct proposed an amendment to the American Lobster lobster population studies is in NUSCO (1982, Fishery Management Plan which incorporates 1987a). Four pot trawls, each consisting of five-measures to reduce fishing mortality (e.g., double-entry wire pots (76 x 51 x 30 cm; 2.5 cm 2 maximum size limit, trap limits. seasonal closures mesh) equally spaced along a 50 75 m line buoyed and closed areas) If the management objective of at both ends, were used to collect lobsters from resource preservation is not met after three years. May through October. Pot trawls were set near The lobster fishery in Connecticut is almost rocky outcrops at three stations'(Fig.1). Pots set completely dependent on new animals that molt in Jordan Cove (average depth 6 m) were 500 m into legal size each year. Lobsters in the Millstone east of the Millstone discharge. The intake station Point area have been studied extensively since 1978 (average depth 5 m) was 600 m west of the
- to determine if operation of the Millstone Nuclear discharge near the power plant intake structures, Power Station (MNPS) caused changes beyond and the Twottee station (average depth 12 m) was )
1 Lebster Studies 11 I
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i V Pmnt T s.e.n r e., ( , Fig.1. location of the Millstone Nucicar Power Station (MNPS). and the three lot > ster sampimg stations (e). JC= Jordan Cove. IN = lntake, Tr=hotree-located south of Millstone Point, about 1600 m numbered international orange sphyrion tag offshore near Twotree Island. Beginning in 1984, (Scarratt and Elson 1965; Scarratt 1970), and pots were individually numbered to determine the released at the site of capture. Recaptured tagged variability in catch among pots, and to provide lobsters, severely injured or newly molted ' soft) more accurate values for catch-per-pot than an lobsters, and those smaller than 55.mm CL 'ere average catch-per-pot based on a total of 20 pots released untagged after recording the above daJi. per sampling location. Pots were hauled on Beginning in 1981, the size at which femaas Monday, Wednesday, and Friday of each week, became sexually mature was estimated by weather permitting; on holiday weeks pots were measuring (to the nearest millimeter) the checked on the first and last work days of each maximum outside width of the second abdominal week. On each sampling trip, surface and bottom segment of all females. Female size at sexual water temperatures and salinities were recorded at maturity was estimated by the carapace length each station. I.obsters larger than 53 mm carapace corresponding to the inflection point of the curve length were banded to restrain chelipeds, brought obtained by plotting the ratio of abdominal width' to the laboratory, and kept in three separate tanks to carapace length against carapace length (Skud supplied with a continuous flow of seawater, After and Perkins 1969; Krouse 1973). lobsters were removed, pots were rebaited with Lobster larvac have been sampled from 1984 to flounder earcasses and reset in the same area. On 1993 during the period of their occurrence (May j Fridays, lobsters caught that week were examined through July) at the discharges of Units 1,2 and 3. and the following data iccorded: sex, presence of . Samples were collected with a 1.0 x 6.0 m conical eggs (berried), carapace length (CL), crusher claw plankton net of 1.0 mm mesh. The volume of I position, missing claws, and molt stage (Aiken cooling water sampled was estimated from the '! 1973). Imbsters were tagged with a serially average readings of four Oeneral Oceanic 12 Monitoring Studies,1993 I
flowmeters located in the mouth of the net; about many pots contained no. legal size lobsters). Both 4000 m' of cooling water were filtered in each geometric means of all lobsters and A-means of-sample by deploying the net for 45-60 minutes. legal size lobsters were used to compare annual Day and night samples were collected four days a variation in CPUE. In the following Results and week in all study years. Each sample was placed in Discussion section, the geometric mean abundance a 1.0 mm mesh sieve and kept in tanks supplied of all lobsters is called "mean total CPUE" while with a continuous flow of seawater. Shortly after the A-mean abundance of legal size lobsters is collection, samples were sorted in a white enamel referred to as "mean lega? CPUE" The pan: hrvae were examined for movement and distribution free, Mann Kendalt test (Hollander classified as live or dead. Lobster larvae were also and Wolfe 1973) was used to determine presence classified by stage according to the criteria of significant trends in the time series of annual established by Herrick (1911). The abundance of CPUE data, and of several other selected larvac in entiainment samples was standardized as population characteristics. Trend slopes, when the number of larvae per unit-volume. The significant, were calculated using Sen's estimator of seasonal (May through July) mean density was the slope (Sen 1968; Gilbert 1987). calculated as the mean of the assumed " delta" The influence of water temperature on lobster distribution, referred to as A mean (Pennington molting was examined by estimating the time when 1983; NUSCO 1988a). To estimate the total lobster molts peaked each year and correlating the number of larvae entrained, the A mean density annual molt peaks with water temperature. Time was scaled by the total volume of water pumped of molting peaks was estimated by the inflection through the plants during the sampling period. points of the Gompertz growth function fitted to Impingement studies were conducted at Unit I data reflecting the cumulative percentage of and 2 intakes from 1975 through 1987; results molting lobsters at weekly intervals during the summarized in N USCO (1987a) included estimates molting season. This. growth function has Ihe of total number of lobsters impinged, as well as form: mean size, sex ratio, proportion of culls, and _ survival probabilities for impinged lobsters. C,- 100e -' A(, p) Impacts on the local lobster population associated , with impingement of lobsters at Units 1 and 3 where C, = cumulative percentage of molting were mitigated by installing fish return sjstems in lobsters, the intakes, which return impinged organisms to t= lime in weeks, LIS (NUSCO 1986; 1987b). Subsequently, p= inflection point scaled in weeks NUSCO and the CT DEP agreed to discontinue from May 1st, and impingement monitoring (NUSCO 198Sb). k= shape parameter. Catch-per-unit effort (CPUE,i.e., the number of lobsters caught per pothaul) was used to describe The first derivative of the Gompertz function with the annual abundance of lobsters in the MNPS respect to time yields a " molt frequency" function area. Because these CPUE data are ratios, which which describes the distribution of annual molts. are not additive and have an asymmetric The times of annual molting peaks were then distribution about the arithmetic mean, the correlated with mean bottom water temperature geometric mean was the chosen statistic to analyze during May to investigate a possible relationship trends in CPUE. The geometric mean is better between water temperature and molting. suited for constructing asymmetric confidence intervals for skewed data (Snedecor and Cochran Results and Discussion 1%7; McConnaughey and Conquest 1993). Annual geometric mean CPUEs were calculated -
' for all lobster sizes.
Temperature and Salinity The annual abundance (CPUE) of legal-size lobsters in the MNPS area Water temperature and salinity were measured was estimated by using the A mean. The A-mean on each sampling trip from May through October was a more appropriate statistic for describing the (1979-1993). Monthly mean surface water CPUE oflegal-size lobster, since a large number of temperature at all stations ranged from 9.4 to zero observations were present in the data (i.e., lobster Studies 13
p' ) li: TABLE 1. Mean monthly surface and bottom water Salinities were similar during 2-unit and 3-unit temperatures measured at each station dunna 2 unit (1979-85) operationt mean surface and bottom water and 3-unit studies (1966 93). salinities ranged between 29.4 and 31.6%. Due to Temprature the spring freshwater runoff, salinities were l Surface nonom generally lower at each station in May and June. 2.Umt 3Uma 2.Unii 3-Uma Abundance and Catch-per-Unit-Effort MAY 10.2 12.4 9.2 9. , Number of lobsters caught during 1993 (10.195) JUN 15.1 17.1 13.9 14 4 was the second highest annual total catch observed JUL 19.5 20.8 18 0 18.1 during either 2-unit (6.376-9,109) or previous 3-AUG 21.2 22.2 19.9 20 0 unit (7,10611,438) operational st udy periods when 3$ g fN 2j 2 20 traps were used at each station (Table 2). The lower catches from 1978 to 1981 of 2 unit studies in s e (1,824 3,259) occurred when only 10 wire pots were used at each station. The geometric mean - MAY 10.1 11.1 9.3 10 I total CPUE for 1993 of 2.301 lobsters / pot was also
! 15 the second highest value reported since the study AUG 20.7 2Lo 20.1 20.2 began in 1978 (2-unit range 0.904-2.006; previous SEP 19.8 20 1 19.4 19.5 3 unit range 1.531-2.457).- In general, total CPUE ocr 16 1 16.5 15.9 R1 during 2-unit studies (1978-85) was lower (1.364)
I" *
- than that observed during 3 unit studies (1986-93; 1.810), and a significant increasing trend -
MAY 9.4 9.9 89 9.4 (slope =0.048, p=0.03) was observed in the time JUN 14.2 14.7 G7 14,1 series (1978-1993) of total CPUE. The a-mean JUL 18.3 18.4 in tu CPUE of legal. size lobsters (e 82.6 mm) was 0.080 tr ocr f 15 4 f. 15.9 15.9 1 15.8 I" I#' .which was vithin the range of values reported in other 3 umt studies when the legal size was 81.0 mm (1986 88 a mean range =0.079-0.086), 81.8 mm (1989 a-mean=0.065) and 82.6 (1990 92 21.2*C during 2-unit studies and was lower than A mean range = 0.076-0.091 ). However, legal the range of monthly means during 3-unit studies CPUE during 1993 was lower than any legal CPUE . (9.9 22.2"Cl Table 1). Bottom water temperatures reported - in 2 unit studies (1978 85 A mean ranged from 8.9 to 20.l*C during 2-unit studies and range = 0.098-0.173). legal catches in our traps ~ from 9.4 to 20.2"C during 3-unit studies. When have significantly declined since 1978 (slope = water temperatures from the three stations were -0.005, p=0.002), most likely due to _ a twofold compared, the highest temperatures were recorded escalation in fishing effort since 1979 (NMFS at Jordan Cove during both 2 unit (10.2-21.2"C) 1993) and the increase in minimum legal size in and 3-unit studies (12.4 22.2*C). In general, 1988. temperatures (surface and bottom) at Jordan Cove In our study area, more than 90% of the legal-and intake (4-6 m depth) were similar and size lobsters had recently molted from the sublegal consistently warmer than at Twottee (12 m depth). size class. Since the legal size was increased from " These temperature data agreed with results of 81.0 mm in 1988, through 81.8 mm in 1989, to 82.6 hydrothermal studies, which indicated that a 2.2"C .mm at present, the a mean CPUE for lobsters isotherm resulting from 3-unit operation could e 81.0 mm (the old legal size) increased each year extend into the Jordan Cove area. In addition, a from 1989 (0.112) to 1992 (0.208).' The 1993 0.8"C isotherm extends 600 m from the discharge CPUE of lobsters e 81.0 mm (0.197) was the to a depth of 3 to 5 m (NUSCO 1988c), and may second highest reported in this study. The greater reach the bottom 500 m from the discharge at the CPUE of lobsters between 81.0 and 82.6 mm Jc.Jan Cove and intake sites where some of the indicates that the regulation increasing the legal pot trawls are deployed. size has been effective. The increases in total 14 Monitoring Studies,1993
q 1 8 TABI E 2. Catch statistics for lotsters caught in witc pois f rom 1978 to 1993. Total numter Numtier pots Geometric 95% C.l. Delia 959 C.I. 6 lotster caught hauled mean total CPUE mean legal CPUE a 810 mm t 81.0 t 81.8 e 82 6 1978 1824 1026 1 600 1.454 1.761 0.173 0.118 0 096 0144 0.202 1979 3259 2051 1.404 1.302 1.513 o I78 0.101 0.079 0.107 0 148 1980 2856 2116 1.103 0.997 1.221 0 609 0 076 0 063 0 092 - 0.126 1981 22M 2187 0.904 0.839 0.974 0.098 0.079 0 069 0.083 - 0.113 1982 9109 4340 2.006 1.925 2.089 0.165 0.126 0.10n 0.144 0186 1983 6376 4285 1.331 1.250 1.418 0.148 0.109 00'O 0 128 , 0.168 1984 7587 4550 1.607 1.540 1.677 0.159 0.120 0.104 0. t 40 - 0.179 1985 7014 4467 1.352 1.252 - 1.460 0.los 0.080 0.068 0.090 0.120 1986 7211 4243 1.585 1.501 1.673 o 056 0 060 0 (Ll9 0.074 0 097 1987 7280 4233 1.033 1.562 1.707 n 079 0.054 0.046 0.070 0 089 1988 8871 4M7 1.929 1,846 2,015 0.079 0 052 0 047 0 068 0 091 1989 7950 4314 1.729 1.645 - 1.817 0.112 OM 0053 0 097 - 0.126 1990 7106 4350 1.531 1.455 1.610 0 161 0 102 o n76 0 143 0 179 1991 7597 4404 1.542 1.437 1.654 0.183 0 117 0.094 0.159 0.20o 1992 11438 4427 2.457 2.352 2.565 0.20s 0 114 o nas 0186 0.229 1993 10195 4194 2.301 2.198 + 2.408 0.197 0.111 0.ono 0.175 0.219 ' 2 Unit 78 85 40261 250 1364 1337 1.403 0.134 0.100 0 085 0.127 0 141 3-Unit 86-93 67648 34' 1.810 1.775 1.846 0.138 0.084 0 006 0.131 - 0 144
- 10 wire pots used at each station from August through Octo!wr 1978. and from May through Octoter 1979-81: 20 wire pots used at '
each station from May through Octoter 1982 93. 3
- The minimum legal 4ize from 1978 to 19s8 was 810 mm (3 /3 m). mimmum legal +tze was mercased in 1989 to 81.8 mm (3 '/yi n). and 3
in 1990 to 82.6 mm (3 /4 in). CPUE during the past two years, coupled with the nnge of CPUEs reported since 1978 (Jordan Cove greater number of lobsters between 81.0 and 82.6 0.753 2.642 and Intake 0.920-1.908). A significant mm observed in recent years,inay lead to higher increasing trend (from 1978 to 1993) in total legal catches in the near future as pre-recruit CPUE was identified at Twotree (slope =0.101, lobsters (one or two molts from legal size) moli p=0.003). No trends in total CPUE were evident into the legal size class. However, continued at Jordan Cove or intake. The pattern of legal increases in fishing effort may preclude any CPUE among stations during 1993 was similar to increases in legal CPUE. A strong recruit class that of total CPUE. Legal CPUE (lobsters t 82.6- , was observed in 1982 and the percentage of legals mm) was highest at Twottee (0.107) and lower at y caught in 1983 increased by almost 3'7c. Record the nearshore Jordan Cove (0.065) and intake landings were reported for Lls in 1983 and 1984. (0.069) stations. Another strong recruit class was observed during Seasonal patterns of lobster abundance have 1988 and although the minimum legal size was been observed since 1978; in general,' loMDr increased from 1988 to 1989, higher landings were catches (total and legal) were highest in June or reported in ' LIS in 1989 (2.7 million pounds) July, and lowest in October During 2 unit studies compared to 1988 (2.4 million pounds). (1978 85), overall total CPUE was highest in July, Total and legal CPUE at each station are whereas peak ratches occurred earlier (June) l preserted in Figure 2, - Total CPUE of 2.957 during 3 unit studies (1986-93; Fig. 3). Similarly, lobsters / pot at Twottee during 1993 was the the abundance of legal-size lobsters peaked in Junc - highest reported in this study (previous range during 3 unit studies,which was earlier than during 0.988-2.941: Fig. 2). At the nearshorc Jordan Cove 2 unit studies (July). Catchability of lobsters is ; and Intake stations, the total CPUEs during 1993 directly. influenced by water temperature; when . l of 2.306 and 1.786, respectively, were within the water temperature rises above ItrC, lobster activity ! Lobster Studies 15
sa c 50 s oo on 3 oo JORDAN COVE 24 o .S o 2.n g 2 so a4
^
t oo oM m g y3 , ,3, , I "5. UN 32s o.31 u 2 oo A 2 $ 75 d "3 . '",*4 2m g i ho . 25 $ 6 ,ys, aa n j>iMim ,t
." ~3 o ro ;
\
g 1.2$ . o 2e ' 16 0 o 1.co- g
" on ,
O il 7, a on oic y om * " ~ 8 aso 2.,,. o
',{.1A:=
- -. " .. o,,H ..y. . . o o* c,'* il o- ...
O WAy JUN Jyt,, AUG ${,p 007 Fa 4 ao et a2 e3 es as as a7 es as 90 si 82 s3 IM-f wart rotscrut 5 5- 5 V'"J io'4 0'UC p y g u.es ssex crus y"-w 3 uws arx crut 3 25 o So 3 co MA4 o.45
^
2n r Dg. 3. Monthly mean total CPUE and mean legal CPUE ror 120 '# j lobsters t 81.0 mm caught dunng 2. unit studies (19781985) and as a 33 r- 3 unit studies (1986-1993). 2m .o so f [", 3 o 2s n the significant (p<0.05) variation in lobster catch j is g N' c 2o F., among the 20 traps used at each station, the s im o in 7 incidental catch of other species in the traps was - g 'o"so o . [d,< o.io I shown to influence lobster catches in previous 3 x[.. <'},..{. N.g..y ,o. , . o os j,, studies (NUSCO 1987a,1993). During 1993, om em lobster CPUE was influenced by catches of spider and hermit crabs at intake, and of whelks and am o so spider crabs at Twotree (Table 3). No species
** ** o .3 affected lobster catch at Jordan Cove during 1993.
-[ o .o E Spider crab' catches at intake continued to be high during 1993 (n=9,253) and have inuuenced 22 on $
o so y lobster catches in all but one year since 1984.
-[
f ,, .A 4-on n Additionally, catches of whelks have had a o 2a d significant influence on lobster CPUE in seven g in.
. E im a
k,.ief'[.'o,eo f oo T previous study years (Table 3). Incidental catches g [',*, o o io l of other species influence lobster catches by s o3 o os ,i occupying space in the trap, consuming the bait om z om and blocking the entrance to the trap. Throughout a n e si n u u as es v u n so o u " the North Atlantic Ocean, researchers have demonstrated competition, niche segregation and Fig 2. Mean total CPUE (geometric mean s 959 C.I.) and nteractions between lobsters and crabs in field and mean legal CPUE (A-mean e 9551 C.I.) ror lobsters t 81.0 mm caught at each Station from 19"i3 to 1993 (O= A-mean legal laboratory Studies (Richards et al.1983; Cobb et CPUE ror lotsters a 82.6 mm). al.1986; Richards and Cobb 1987; Hudon and (e.g., feeding, movement, and molting) incrcases (McLeese and Wilder 1958; Dow 1966,1969,1976; Population Characteristics - Flowers and Saila 1972; NUSCO 1993). Accordingly, warmer sea temperatures during the . 3-unit study period (1986 93), relative to the 2-unit Size Frequency studies (1978-85; Table 1), may be responsible for the earlier peaks in lobster abundance. The mean carapace length (CL) of 70.8 mm ,
~'
The inherent variability in lobster catch during 1993 was larger than the range of previous associated with the use of- passive gear (lobster 3-unit CLs (69.5-70.2 mm) but within the range of traps) was examined in our study. In addition to CL means reported in 2-unit studies (range of 70.7-71.8 mm: Table 4). Legal-size lobsters (t 82.6 16 Menitoring Studies,1993 P
TABLE 3. Total number of lobsters and incidentas catch of other species caught in traps from 1984 1993. 1984 1985 1986' 1987 1988 1989 1990 1991 1992 1993 tobster 7587 7014 7211 7280 8871 7930 7106 7597 11438 10195 Rock, Jonah crab 465 177 158 108 79 583' 843' 1063' 2033' 1130 Spider crab 3237' 1950 1344' 1754' 723P 693P 11228* 9716' 13086' 10722' , liermit crab 428 496 435 721' 711 590 470 324 286 403' Ulue crab 40 21 26 44 71 43 63 148 110 70 Winter flounder 45 40* 19' 30 28 8 13 22 10 11 Summer flounder 60 24' 38' 35 28 4 16 16 14 11 States 15 17 33 14 16 54 40 47 53 47 Oyster toaJfish 76 67 58 14 33 10 16 12 10 8 Scup 27 90 28s 169 97 84 237 176 185 95 Cunner 141 207 206 167 181 67 71 76 152 75 Tautog 39 250 Ivo 208 44 83 50 82 09 119 Sca raven 20 19 6 2 0 2 4 1 0 0 Whells 66 78* 164' 132' 27 84' 44' 56' 178* 67* (*) Covanance analpis identihed these catches as sigmhcant factors affectmg lotuler CPUE (p< 0 05). TABLE 4. Summary of lobster carapace length statistics for wire poi catches from May through October, 1978-1993 1 N' Carapace length (mm) Prrcentage of Range Mean295G Cl legal sizes" t 81.0 t 81.8 t 82.6 1978 71.420.33 1508 53 111 M 5.9 4.8 1979 2846 44 100 71.220.26 6.6 2d 5.1 1980 40 96 2531 70.7 2 027 M 5.0 4.1 1981 1983 43.% 71.0 2 033 M 7.6 6.6 1982 7835 45 103 708 2 015 M 5.7 47 1983 5432 40 121 71.720.19 9J 7.4 6.3 19s4 71.820.18 6156 45 107 M 73 6.4 1 1985 5723 713 2 0.17 38 101 M 5.1 43 1986 5961 36-107 70,120.17 M 36 3.0 1987 36-99 70.220.17 5924 M 3.2 2.7 1988 7145 21 97 69.5 2 016 U 26 23 1 1989 6715 1990 34 107 69.9 2 017 45 M 2.9 j 6040 36 102 702 2 020 7.4 59 4,j , 1991 6449 31 101 70.220.20 tL5 6.5 - So 1992 9594 20 103 70.120.15 64 4.3 M 199) 84S7 30 102 708 2 015 67 46 M 2 Unit 78-85 34014 38 121 713 2 0.07 7.5 63 53 3-Unit 86-92 56315 20-107 70.1 2 006 5.7 43 33
- Recaptures not included, i
3
- The nunimum legal she from 1978 to 1988 was 81.0 mm 13 3 / in), mmimum legal see was mereased m 1989 to 818 mm (3 '/nin). and -{
1 in 1990 to 82.6 mm (3 4/ in). ] mm) comprised 3.3% of the total catch during However, the 1993 percentage was lower than the 1993, which . was within the range of catch 3.5% reported in 1989 when the legal size was 81.8 percentages reported from 1986101988 (3.2-4.4%) mm. Both the percentage of lobsters in each legal i wtan the legal size was 81.0 mm and from 1990 to size category (i.e., 81.0,81.8,82.6 mm) and mean 1992 (3.3 5.0%) when the legal size was 82.6 mm. carapace length were lower during 3. unit studies Lobster Studies 17
TAD!.E 5. Summary of lobster carapace length statistics for wire not catches from M,w throuch October, 1978 1993 JORDAN ' N* Carapace length (mm) Percenlage of COVE Range Mean 959 Cl legal sires" t 810 2 M1 R r 82 6 1978 489 54 111 703 2 0.54 M 3.5 2.7 1979 1138 46-96 70.7 e 0.39 M 5.7 4.2 1980 '831 40 93 702 2 0.45 M 3.5 2.5 1981 556 45 93 70.620.64 M 6.7 5.9 1982 2323 49 % 69.820.26 M 4.0 3.2 1983 1965 40 100 71.0 2 032 M ' b.5 5.5 1984 1999 52 107 70.7 = 0.29 M 4.4 4.0 1985 1722 48-96 71.120.32 M 5.0 4.1 1986 1748 38 99 69.8 e 0 31 M 2.6 2,1 1987 1690 44 95 70.2 2 032 M 3.0 . ' 2.5 1988 2239 21 97 69.220.29 M 2,7 - 2.3 1989 2077 M-98 69.820.30 4.0 M 2.6 1990 2108 36 94 69.4 2 033 70 4.9 40 1991 1834 38 101 693 2 039 7.6 6.1 - M 1992 3125 20-103 69.0 2 027 5.5 3.7 M 1991 2627 44-102 700 2 024 65 43 2.7 2-Unit 78 85 11023 40-111 70 6 0.13 60 4.9 4.1 t-linit 491 1744R 20 103 69 5 0 11 52 38 29 INTAKF 1978 #A5 55-110 71.820.50 J-9 6.7 5.7 1979 1087 50 100 71.4 2 041 M 6.6 5.4 1980 855 46-95 70.6 0.45 M 43 36 1981 6S6 43 95 69.2 2 053 4_4 34 2.9 1982 2402 51 103 702 2 0.27 M 4.1 32 1983 1436 52 110 71.2 2 037 M 5.5 4.9 1934 1830 45-105 70 5 0 32 M 4.9 4.2 1985 1215 44 sv 71.2 2 037 M 4.9 43 1986 1888 50 107 693 2 031 M 36 3.0 1987 lid 7 47 94 70.21 032 0 3.5 - 3.0 1988 2253 39-95 n9 2 e 0 27 M 2.0 1.8 1989 2005 39 98 69.0 2 032 4.0 M 24 1990 1721 M-102 69.4 0 3n 61 -44 M 1991 1877 31 100 689 : 035. 6.5 51 M 1992 2575 22 97 69.520.29 6.4 4.6 M 1993 2275 47 95 701 t 0 10 '67 49 16 2-Unit 78-85 10156 43 110 70.7 2 013 60 4.9 4.2 Alfnit 84 91 162R1 22 107 69 4 t 011 52 39 30 TWOl?tl'E 1978 374 53-94 72 2 0 67- M 7.8 59 1979 621 44 94 71.8 2 058 9J 8.1 6.0 1980 M5 40 9n 713 1 049 M' 7.1 60 1981 741 4846 73.0 2 054 L4U 12.2 10 4 1982 3110 45 102 72o ! 0.05. 9 J 81 7.0 1983 2031 43 121 72.8 2 032 1M 9.7 81 1984 2327 50 105 73.7 = 0.29 W !1.7 10 3-1965 278o 38 101 71.520.25 62 5.2 4.4 1986 2325 36 97 71 0 0.27 M 44 36 1987 2547 M-99 70.2 e 0.27 M, 31 2.6 1988 2653 M 95 700 2 007 y- 30 2.8 1989 2633 34 107 70.620.28 5.4 M 3.4 1990 2211 39-102 71.7 2 033 10 0 7.9 J 6 1991 2738 38-98 7162 030 10.5' 7.7 M-1992 3894 32 % 71.3 2 023 7.1 4.5 M 1993 MR5 30 92 il 9 0 23 67 46 16
- 2. Unit 78-85 12835 38 121 72 3 e 012 10 0 - ; 8.5 73 3 Unit % 91 22586 M 107 71.1 2 0 t o n5- 49 39
- Recaptures not included 'The mammum lepi me from 1978 to 1988 was 81.0 mm (3 Il m). mmimum lepl we wn merceed m 1989 to 81.8 mm (3 '/g m), and in 1990 to 82.6 mm (3 '/, m) 18 Monitoring Studies,1993
(5.6%, 4.2%, 3.4% and 70.0 mm, respectively),. TABLE 6. Female to rnale sex raoos" of lobsters caught in t?,an during 2-unit studies (7.5%,6.3%,5.3%, and Ske Pon from May through October. 1978 1993. 71.3 mm). The percentages of legallobsters in our -catch have significantly declined since 1978 Jordan iniate Twoiree Ali (slope = 0.328, p<0.01), probably due to increased cove suoans fishing effort, which has more than doubled since 1978 (Blake 1991; NMFS 1993). g,, g, q,7 . g Carapace length statistics of lobsters caught at 1979 n68 as3 us . a82 each station (Table 5) followed trends similar to 1980 0 66 o.90 1.15 0 88 those observed for the total catch.1.argest lobsters 1981 0.70 0.71 1.19 c.86 were caught at Twotree (mean CL range 70.0-73.7 1982 0.62 0.6t> 1.09 0.79 - 83 7 mm) and the mean size ranges of lobsters caught at the nearshore Jordan Cove and intake stations
]5 ,,
1985 0.70 0.67 1.38 0.97 were 69.2-71.1 mm and 68.9-71.8 mm, respectively, 1986 0.65 0.73 1.26 0.87 The mean CL at Twotree during 1993 (71.9 mm) 1987 0.71 0.63 1.24 o.88 was the largest observed in 3-unit studies (70.0 1988 0 68 0.72 1.15 0.85 71.7 mm), while those at Jordan Cove and Intake were withm, the range of previous 3 umt studies
, []
1991 [ u.51 0 57 [8, 1.13 0] v.74 , (Table 5). Mean lobster size at all stations was joy: o 43 a47 i.45 a73 larger during 2 unit studies than during 3-unit 1993 0 47 c.59 1.59 0.84 studies (Jordan Cove 70.6 vs. 69.5, intake 70.7 vs. 69.4, Twotree 72.3 vs. 71.1 mm). The percentage
. 2.Una 78 85 0 67 07: 1.21 o 86 of legal lobsters was also greater during 2 unit 3.umi 86 93 0.56 0 62 1.24 o so studies; at both Jordan Cove and intake,6.0% of the catch was legal size (t 81.0 mm) during 2-unit
- Recapiures not included.
studies and 5.2% during 3-unit studies (Table 5). The Twotree station consistently yielded more increased each year over the past four 3 cars, with legal-size lobsters than did nearshore sites; 10.09 the 1993 sex ratio of 1.59 the highest reported in of the catch was legal size during 2 unit studies this study (previous range 0.90-1.45). The overall and 6.5% during 3 unit studies. Since 1978, legal ratio of females to males was higher during 2 unit catches at each station have significantly declined studies (0.86 female per male) than during 3-unit and lobstermen in our area have reported a 15- studies (0.80 females per male). At Jordan Cove 20% decline in their legal catches over the past and intake, sex ratios during 2-unit studies were few years. Larger declines (50%) were reported 0.67 and 0.72 females per male, higher than the ' from lobstermen west of the Connecticut River. In ratios during 3-unit studies (0.56 and 0.62, 1992, substantial declines in landings were respectively), but at Twotree, the female to-male i observed throughout the range of lobsters (U.S. ratio was lower during 2-unit (1.21) than during 3-
-13% and Canada 20%; NMFS 1993). unit studies (1.24). The occurrence of more females than males at Twotree 'has remained >
Sex Ratios consistent since 1975 and different from sex ratios at other stations (Keser et al.1983). Female-to- , The sex ratio of lobsters collected during 1993 male ratios of lobsters caught by commercial - , was 0.84 females per male, compared to a range of lobstermen in LlS ranged between 1.06 and 1.81 O.71-0.88 in prior years of 3 unit operation and (Smith 1977) and more recently, Blake (1988) 0.79-0.97.during 2-unit operation (Table 6). Sex reported higher sex ratios oflobsters caught in the ratios during 1993 at the two nearshore sites, eastern LlS commercial fishery (range 2.61-6.29); Jordan Cove (0.47) and Intake (0.59), were within Several factors have been suggested to cause a , the range of previous 3-_ unit studies (0.43 0.71 and predominance of females in the commercial 0.47-0.73, respectively), but below the range of 2 fishery: differences in female lobster behavior unit studies (0.60-0.79 and 0.66 0.97, respectively). related to molting and reproduction, fishery Female to male sex ratios at Twotree have regulations designed to protect egg bearing females, and the fact that mature females molt less Lobster Studies 19 (
frequently than males (Ennis 1980). The overall collected in 2 unit (62 mm) and 3-unit studies (60 sex ratio of lobsters in the MNPS area is close to mm) supported the results of the morphometric the 1:1 sex ratio reported by other researchers for relationship between the abdominal width and ! predominantly sublegal (< 81.0 mm CL) carapace length. These individuals were between -l populations oflobsters (Herrick 1911; Templeman 50 55 mm CL when oviposition first occurred 1936; Ennis 1971,1974; Stewart 1972; Krouse (assuming 14% growth per molt). Briggs and i 1973; Thomas 1973; Cooper et al.1975; Briggs and Mushacke (1979), using the same morphometric j Mushacke 1980). technique, found that females in western LIS begin , to mature at 60 mm CL and most are mature at 1 Reproducdon about 80 mm CL. In contrast, Gulf of Maine 1 females seldom become sexually mature at less Several methods have been used to determine than 81 mm CL, and only a small percentage are - the size at which females become sexually mature, mature between 81 and 90 mm CL (Krouse 1973; with the presence of external eggs the obvious Krouse et al.1993). Earlier maturation of females indication of female lobster maturity. Additionally, in LIS than in the Gulf of Maine can be attributed tbc method first described by Templeman (1935) is to the warmer LIS water temperatures (Smith that female abdominal width markedly increases 1977; Aiken and Waddy .1980). The sexual-during maturation. Calculation of the abdominal maturity of males was not investigated in our study width to carapace length ratio and comparison to because other researchers documented that the size CL provides an index of female size at sexual at which males become mature varies only slightly maturity (Skud and Perkins 1969; Krouse 1973). throughout the range oflobsters. In western LIS, Mean ratios of abdominal width to carapace length males are mature (i.e., produce mature were calculated for each 5 mm CL and plotted spermatozoa) at 40 to 44 mm CL, and over half against the carapace length of lobsters collected for are mature at 50 to 54 mm CL (Briggs and 2-unit (1981-85) and 3-unit (1986-93) operations Mushacke 1979); in ' northern waters (Maine), and for 1993 alone (Fig. 4). During 1993, females males also begin to mature at relatively small sizes began to rnature at about 55 mm CL, and all (509 mature at 44 mm CL: Krouse 1973). females were mature above 90 mm CL. The close The percentage of berried females collected correspondence between the 2- and 3 unit curves during 1993 was 12.2% which was the highest in Figure 4 indicates that female size at sexual value reported since the study began in ' 1978 maturity was similar during both operational (previous range 3.1-12.19; Table 7). More berried periods. The size of the smallest berried females females were caught at Twottee (19.49) than at the nearshore Jordan Cove (3.19) or Intake
% ., .. (2.7%) stations; this distribution pattern has been avw consistent since 1975 (Keser et al.1983). The
{'* t b-- ')
,p. [; percentage at Twotree was the highest since the Bou wm
- i study began (previous range 5.3-19.3%), while the
* ?
i . percentages at Jordan Cove and Intake were within
' o eo
,y" the range of previous 3-unit (2.4 3.49 and 1.5-c.
4.0G, respectively) and 2 unit percentages (0.8-0 5$
! 3.69 and 0.9-4.59, respectively). The percentage .
i , of berried females wss higher during 3. unit (7.79 ) '
" .o .o .c n aa w ioo ,,, than during 2. unit operations (4.3%). The mean.
casaccumcm > > carapace length of 75.6 mm for berried females collected during 1993 was within the range of 2-unit:y-1.28.(313'10' ):+gelo* -(1.85'lo*p3, r2 -30 average sizes reported in previous 3-unit studies 3-unit:y-l.03{2.32*104 p+(3.61'10d y -(1.61'10*y'. r2 =32 (75.3-78.1 mm), but below the range reported in 2- : 1993; y-134.go9'10 2)x+(6.85'to d -(3 45'10+)x', r .31 unit studies (77.0-81.2 mm; Table 7). On average, Rg 4 Morphomeme rclationship between the abdominal mddi berried females collected during 3-unit studies to carapace tength ratio (y) and the carapace length (x) for were smaller (76.5 mm) than during 2 unit s'tudies femate khers dunng 2-umi (--) and 3.umi uudies t. .) and (79.4 mm), due to Ihe larger proportion of dunn 1993 (o o o). sublegal sized berried females collected since 1986. 20 Monitoring Studies,1993
TABLE 7. Percentage of berried females caught at each station and annual carapace length statistics from 1978 93.
~
Percentare or berried femnies All Jordan intake Twotree N' Carapace t.ength (mm) Percentage of stations Cove Range Mean 2 95?! C.I. sublegal sizes *
< 81.0 <81.8 < 82.6 1978 3.4 1.4 2.6 53 58 74 - 88 80.121.04 1} 78 78 1979 3.1 1.9 2.7 7.2 70 64 93 80.5 e 1.28 29 64 70 1980 33 3.5 1.8 5.6 71 66 - 93 79.121.27 70. 73 79 1981 4.2 1.6 2.7 7.1 82 69 97 81.2 e 135 !! 59 62 1982 3.1 0.8 0.9 6.1 108 64 - 99 80.0 e 1.08 g 66 70 1983 4.7 2.1 3.2 8.5 123 66 - 103 80.5 e 1.04 g 65 67 1984 6.2 3.6 3.5 10.6 173 62 - 95 79.120.87 g 75- 76 1985 6.2 3.5 45 8.5 171 63 94 77.0 e 0.81 B 85 86 1986 4.8 30 23 8.0 135 65 94 78.020.95 7Z 80 83 1987 5.7 3.2 1.9 9.6 158 62 - 90 76.520.67 g 92 93 1988 3.8 2.4 1.9 6.4 124 63 90 76.9 e 0 82 8,9 90 90 -
1989 5.4 2.8 33 8.2 161 65 98 773 2 0.78 82 gj 88 1990 6.6 2.7 4.0 11.2 165 65-102 78.120.82 75 81 !?, 1991 8.2 3.2 1.5 13.5 226 62 96 78.0 0.75 71 78 g - 1992 12.1 3,4 1.7 193 491 60 93 753 2 0.44 89 92 g 1993 12.2 3.1 2.7 19.4 476 62 90 75.6 2 043 88 91 y 2-Umt 78-85 43 2.0 2.2 7.1 856 62 - 103 '79.4 2 039 68 72 74 3-Unit 86-93 7.7 2.9 24 12.8 1936 60 - 102 76.520.23 84 88 90
- Recaptures not included.
- De minimum legal size from 1978 to 1988 was 81.0 mru (33 /3in). mmimum legal size was mcreased in 1989 to 81.8 mm (3 'Inin), and 1
in 1990 to 82.6 mm (3 4 in). During 1993, 93 % of the berried females were Afolting and GroWIh below the minimum legal size of 82.6 mm. High + rates of fishing remove most females shortly after The most important factor regulating molting they reach legal size or after berried females and growth of lobsters is temperature (Alken ; release eggs. The apparent stability of the LIS 1980), resulting in variable seasonal and annual-lobster population, despite current high catches of soft or newly molted lobsters. During exploi.tation rates, may be due to the fact that 1993, the majority of molting lobsters were caught females become mature and bear eggs at sizes well from late spring (end of May) to early summer below the legal size. While undocumented, stock (middle of June). However, in several of the mean fecundity may be lower, as a result of relying previous study years, a second peak in the catch'of on smaller berried females to sustain recruitment, . molting lobsters was observed in autumn (Keser et . which could affect the long-term health of the LlS al.' 1983). The frequency and timing of lobster fishery. The regulation to increase the minimum molts were examined using the Gompertz growth ' , legal size appears to be effective as the percentage function fitted to cumulative percent-molt data for - of berried females in our catch has increased each . 2- and .3-unit studies (Fig. 5).- The inflection - year.' The increase in minimum legal size should points of the growth curves were used.to estimate ' improve ' egg production and subsequent annual dates of peak molting. Annual molting recruitment by allowing more females to spawn peaks were significantly (p<0.05) correlated with before reaching legal size. However, if fishing mean ' May bottom water temperatures. and effort continues to escalate, higher yields (CPUE) indicated that molting occurred earlier when May-duelto increased egg production may not water temperatures were warmer than overage. materialize. Conversely, peaks occurred later when . water temperatures were colder than average. Peak molt - during 2-unit studies occurred on 27 June, which ( Lobster Studies 21
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TA11LE 8. Summary of totwer growth (in mm and as a percentage) at each 6tation for wire pot catches from May through Octolvr 1979 to 1993. Jordan rose Inide Twotree - Growth Growth Growth N (mm) Percentage N (mm) Percentage N (mm) Percentage 1979 33 73 10 6 22 88 12.8 21 11.1 163 1980 38 8.6 12.7 21 8.7 12.5 33 10.1 14.8 1981 29 7.9 11.8 24 8.9 13.1 40 103 15.4 1982 48 9.0 133 55 7.8 12.0 96 9.1 13.2 1983 - 40 8.8 13 4 23 9.5 14.2 71 9.6 14.5 1984 85 9.0 13.8 44 7.8 123 79 8.8 12.9 1985 63 8.4 12.8 25 8.8 13,7 77 80 11.7 1986 6t 9. I 13.5 39 7.5 11.6 69 8.6 12.9 1987 71 7.9 12.0 41 8.6 12.8 67 8.9 3.2 1988 93 8.5 12.8 58 9.5 15.2 104 9.6 14.7 1989 82 9.3 143 72 9.5 14.4 80 9.2 14.1 1990 93 9.1 13.9 51 9. 2 14.2 58 10.2 15.5 1991 57 8.4 12.6 65 8.9 13.4 65 9.M 14.7 1992 107 8.9 13.8 48 8.8 13.2 81 9.4 14 6 1993 68 8.5 13 0 35 8.4 12.7 76 8.6 13.2
- 2. Unit 79 85 336 8.6 12.9 214 8.5 12.8 417 9.2 13 6 3-Unit 86-93 632 8.7 13 6 409 8.9 13 6 600 93 14.1 with summer water temperatures in the Canadian diverted to widening of the - abdomen and Maritimes and suggested that a l#C drop in water development of ovaries. Growth increments at ,
temperature delays the first molting period by a cach station were slightly larger during 3 unit week or more. The influence of varyir)g water studies than during ' 2-unit studies (Table 8).' temperature on the molt cycle was examined by Growth per molt was higher at Twotree during 21 . Aiken and Waddy (1980). Moreover, at 10aC unit (9.2 mnt,13.67c) and 3-unit studies (9.3 mm, lobsters quickly entered the premolt stage and 14.17c), than at the nearshore stations, Jordan ' progressed to ecdysis. Cove (2 unit 8.6 mm,12.9%; 3 unit 8.7 mm, Lobster growth was determined from carapace 13.6%) and Intake (2-unit 8.5 mm,12.8%; 3 unit length measurements of those lobsters that had 8.9 mm, 13.6%; Tab!c 8). Lobster growth molted between tagging and recapture, determined from our tag and recapture studies is incremental growth per molt for the size range of similar to that from other studies conducted in
!cbsters caught in our studies is best described castern LIS, where growth has averaged between using simple linear regressions (Wilder 1953; 12.79 and 15.89 for males and between 12.8%
Kurata 1%2; Mauchline 1976). Regression plots and 15.4% for females (Stewart 1972; Blake 1991).- and parameter estimates of growth for males and in western LIS, growth per molt ranged between females caught during 1993 and in 2-unit and 3- 13.0 and 14.5% for males and between 12.5 and unit studies are presented in Figure 7. Growth 13.57e for females (Briggs and Mushacke'1984; increments averaged 8.9 mm (13.3%) and 8.7 mm Blake 1991). Offshore lobsters were reported to (13.0%) for males and females, respectively during exhibit larger growth (18.7% for males and 16.7% 2 unit studies, which was smaller than the average for females) than inshore lobsters, which was incremental growth during 3-unit studies (males attributed to seasonal migration of offshore 9.1 mm,13.7%; females 8.9 mm,13.7%). The fact lobsters to maintain a' temperature regime of that females exhibited slightly lower growth was between 8* and 14"C (Cooper and Uzmann 1971; expected because of their reproductive cycle; Uzmann et al.1977). energy that could be used for carapace growth is Lobster Studies 23
~+ . - - . -. --- ~ . - . ~ . - - .-
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TABLE 9. Percentage or cults (lotsten missing one or twh demonstrated by Krouse (1976). Throughout New cim) caught in wire pois from 1978 1993. England, researchers have reported the benefits of incorporating escape vents in lobster traps (Krouse Jordan intake Twotree AH and Thomas 1975; Fair and Estrella 1976; Krouse cme stations 1978; Pecci et al.1978; Fogarty and Borden 1980; 1 Krouse et al.1993). ; i 9.8 1978 1979 21.5 17.3 14.7 17.8 8.8 15.5 15.5 Tagging Program ) 1980 13.5 16 4 10.4 13.4 1 1981 13 4 16.7 7.1 12.1 The number of lobsters tagged during 1993 j 1932 13.9 14.1 7.0 11.3 (8.177) was within the range of previous 3-unit t 8 years (5,680-9,126), but higher than the 2-unit 1985 15.1 13 9 7.2 11.1 study range of 2,768 to 7,575 (Table 10). The 1986 10.9 14.7 6.8 lo.o percentage recaptured in our traps was 20.9% and 1987 11.9 14.7 ti.2 10.3 within the recaptme rates observed in both 3-unit fj 7 y ] (l8.1-25.2%) arid 2 unit studies (14.4-23.9%; Table 1990 12.3 1o.2 8. i 11.9 10L Relative to recaptures in NUSCO traps, the r 1991 14.5 14.0 8.2 11.8 percentage recaptured in commercial traps was 1992 11.4 12.9 6.9 10.0 smaller (14.8%) during 1993 and this value was - 1993 11.2 12.6 7.7 10.1 lower than percentages reported since 1978 (previous range 17.0-47.6%). The ' overall , 2-Unit 7845 14.4 15.2 7.6 12 1 percentage recaptured in NUSCO traps was 29 3-Unii s6-93 12.5 14 0 7.4 103 higher during 3-unit than during 2-unit studies, whereas the percentage of recaptures by commercial lobstermen declined from 33.0 9 ' Cu#s during 2-unit studies to 18.4 9 during 3. unit studies. The shift in percentages recaptured in The percentage of lobsters missing one or both NUSCO and commercial traps during 2- and 3 unit claws (culls) was 10.1% of the total catch during operations appears due to the escape vent 1993, which was within the range of previous 3- regulation implemented in 1984 and not to plant , unit studies (10.0-12.2%), but lower than the operation. Installation of escape vents, coupled values reported in 2-unit studies (10.8-15.5%; with the fact that most of our tagged lobsters are , Table 9). During 1993, Twotree had the lowest sublegal, resulted in fewer tagged lobsters retained percentage of culls (7.7%). followed by Jordan in commercial traps. Conversely, NUSCO traps do Cove (11.2%) and intake (12.6%); this ranking of not have escape vents and retain greater numbers. the three stations has remained unchanged since of tagged sublegal lobsters. The mean CL of the study began (NUSCO 1987a,1993). Claw loss lobsters recaptured in NUSCO and in commercial was lower during combined 3 unit studies (10.9%) traps during 1993 were 73.4 and 79.1 mm, than during the 2-unit study period (12.19),likely respectively; both values were within the range of due to the implementation of the escape vent those in previous 2 unit and 3-unit studies (Table regulation in 1984. This regulation requires that 10). Differences between the size of lobsters pots contain a 1% by 6 inch opening to allow recaptured in NUSCO and in commercial traps
- escape of sublegal-sized lobsters, and thereby during the two operational study periods were also .
reduces injury and mortality associated with due to the implementation of the escape vent overcrowded pots (Landers a d Blake 1985). Trap regulation. The overall mean CL in NUSCO traps related injuries were associated with water was smaller during 3 unit (72.8 mm) than during 2- , temperature, fishing pressure (i.e., handling by unit studies (73.9 mm) and larger in commercial lobstermen), trap soaktime, and shell hardness. traps during the two operational study periods (Pecci et al 1978). Of these factors, a positive (79.0 vs. 77.1 mm). Before escape vents were correlation between fishing pressure 1nd the required (1978-83), commercial lobstermen incidence of culls along the coast of Maine was recaptured many of the sublegal-sized tagged 24 Monitoring Studies,1993
TA13LE 10. Imbster tag and recapture sta:istics for NUSCO pots (May Oci.) and commercial pois (Jan Dec ) from 1978 to 1993. l l Nt!SCO Commercul l l Number - Number Percentage - Percentage Mean Number Percentage Percentage Mean l ugged recaptured recaptured legal
- CL(mm) recaptured recaptured legal" CL(mm) ']
1978 2768 498 18.0 16.7 75.5 884 31.9 43.6 81.1 1979 3712 722 19.4 11.5 75.1 1778 47.6 27.2 77.6 1980 3634 522 14.4 18.8 75.7 1363 37.5 27.5 76.4 1981 4246 707 16.7 12.0 74.8 1484 35.0 25.9 763 1982 7575 1282 16.9 10.4 73.2 2519 33 2 23.0 75.5 1983 5160 932 18.1 11.3 73.6 2266 43.9 27.6 76.9 1984 5992 1431 23.9 84 73.0 1290 213 34 3 78.8 1985 5609 1216 21.7 7.7 73.2 1185 21.1 29 3 783 1986 5740 1194 20.8 4.7 72 3 1177 20.4 27.5 78 2 1987 56S0 1356 23.9 5.5 72.8 1160 20 4 25 3 78.9 1988 6637 1725 25.2 43 72.0 1383 20.2 26.7 78.0 1989 6438 1233 19.2 4.4(93) 72.9 1183 18.4 20.7 (24 8) 78.2 1990 5741 1066 18 6 5.5 (12.7) 73 3 1007 17,5 26.5 (32.8) 79 3 . 1991 6136 1109 18.1 7.4 (13.9) 73 4 1228 20 0 33.9 (41.5) 80.8
.1992 9126 1842 20.2 3.9(93) 72.4 1552 17.0 23 3 (28.5) 79.5 1993 8177 1708 20.9 3.6 (9.8) 73.4 1213 14 8 25.4 (47.5) ' 79.1 2-Unit 78 85 38716 7310 18.9 11.0 73.9 127n9 33 0 '. 27.5 77.1 ,
3-Umi 86 93 53875 11233 20.9 4.7(83) 72.8 9903 18.4 2o.1 (31.7) '79.0 3 al size from 1978 to 1988 was 81.0 mm (33/ m). mmimum legal sire was increased in 1989 to 81.8 mm (33 '/ m) and
*1990 The 82.6minimum mm (3 leg /,in). Parenthetical values for percentage legal from 1989 to 1993 and 3-unit stud 81.0 mm carapace length.
lobsters. Since the regulation was enforced, many recaptured in NUSCO traps during 3 unit studies sublegals escaped from the vented commercial (4.7%) was substantially lower than the percentage pots, but were still retained in unvented NUSCO during 2-unit studies (11.09).' Declines were also pots. in eastern LIS, Landers and Blake (1985) noted in the percentage'of legal. sized lobsters noted a substantial reduction in the number of recaptured by commercial lobstermen during the sublegal sized lobsters retained in vented pots, two operational periods (26.1% in 3-unit vs. 27.59 1 without a corresponding decrease in the catch of in 2. unit studies). The declines in percentage of legal-sized lobsters. In Maine waters, Krouse et al. legal. sized recaptures are attributed to an increase (1993) examined lobster catches in traps equipped in fishing effort, which has more than doubled with a variety of escape vent sizes (1 3
/ ,1 "/3 , I '/, since 1978 and, in part, . to the increase in by 5 '/, in). They found that 1 '/, x 5 '/, in vents minimum legal size beginning in 1989.
retained fewer sublegals than did traps with smaller escape vents, and that the overall catch of legals Movemerit was comparable for the 1 '/, and 1 '/, in vented . traps. Lobster mosement was- examined using tag The declining trend observed in the percentage return information obtained from commercial ofIcgal-sized lobsters in the overall lobster catches lobstermen. The average distance traveled .by was reflected in the proportion of recaptured lobsters before they were caught in commercial lobsters that were of legal size. During 1993, only traps was 5.06 km during 1993, which was the 3.6% of the recaptures in NUSCO pots were of longest distance reported' in our tagging study -
- legal size (t 82.6 mm), which was the lowest value (previous range 1.70-3.16 km; Table 11).' During
. reported (previous range 3.918.89: Table 10). 1993. 91% of the recaptured lobsters were caught . The overall percentage of legal-sized lobsters by lobstermen fishing within 5 km of MNPS, Lobster Studies 25
- i
. . _ , , _ r , ~ ..
TABLE 11. "De average distanec (Lm) travelled t y lobsters from Millstone P aint for all commeraal pots. All recaptures
%%in 5 km of MN{'$ More than 5 km from MNPS Number of Average Number (ci) of Average Number (%) of Average tags returned distance (km) tags returned distance (km) tags returned distance (km) 1978 793 3.01 725 (91) 1.71 73 (9) 15.92 1979 1733 1.70 1665 (96) 1.31 68 (4) 11.28 1980 1303 2 09 1257 (96) 1.25 46 (4) 25.17 1981 1478 1.89 1451 (98) 1.49 27 (2) 23 49 1982 2509 2.34 2343 (93) 1.58 166 (7) -13 04 1983 2258 2.88 21:1 (93) 1.70 147 (7) 19.78 1984 1288 2.33 1230 (95) 1.78 58 (5) 13.93 1985 1183 2.84 1077 (91) 1.81 106 (9) 13 40 1986 1172 2.64 1!!2 (95) 1.76 60 (5) 18.82 1987 1157 2.87 1124 (97) 1.77 33 (3) 40.09 1988 1371 3.16 1256 (94) 1.81. 85 (6) 23.72 1989 1165 1.97 1147 (98) 1.79 18 (2) 12.80 1990 1004 2.18 979 (98) 1.80 25 (2) 17.06 1991 1" ' 47 1181 (97) 1.80 41 (3) 21.80 1992 1536 2 68 1485 (97) 1.80 51 ( ) 28 09 a 1993 1209 5.06 1096 (91) 1.90 t 13 (9) 3515 2-Unit 78-85 12550 2.36 11859 (94) 1.57 691 (6) 15.95 3-Unit 86 93 9836 2.89 94 to (9o) 1El 42n (4) 20.82 .
within the range of percentages reported during 2- LIS and Block Island Sound, which suggests a unit studies (9198%), but lower than during migration route for lobsters that exit LIS. A previous 3-unit studies (94 98%; Table 11). number of lobsters (113) were reported caught Lobsters recaptured within 5 km of Millstone Pt. outside LIS along the Rhode Island coast (28), off moved an average of 196 km. during 1993, longer of Block Island (19) and in waters along the south than the distances reported previously (1.25-1.81 shore of Cape Cod (13). Tag returns were aise km; Table 11). An earlier tagging study conducted reported by lobstermen fishing the offshore waters, in eastern LIS by Stewart (1972) demonstrated a in canyons on the edge of the continental shelf strong homing behavior of the nearshore lobster (Block n=7, Hudson n=10 Atlantis n=5, Veatch population. Because lobsters are territerial and n = 2). Similar offshore migrations were noctumal, individuals have a limi ed home range; demonstrated by other researchers working in they leave their burrows at night aad return to the waters from Canada to southern New England same shelters before dawn. Our Jagging studies (Salla and Flowers 1%8; Uzmann et al.1977; indicate a predominance of locatind movement Cooper and Uzmann 1980; Campbell and Stasko which is typical of nearsho;e lobsters in coastal 1985, 1986). waters of castern North America (~lempleman 1940; Wilder and Murray 1958; Wilder 1963; Entrainment Cooper 1970; Stewart 1972; Cooper et al.1975; Fogarty el al.1980; Krouse 1980,1981: Campbell The total number of lobster larvac collected in 1982; Ennis 1984). samples of the MNPS cooling water was '219
- Although our tag and recapture st . dies indicate during 1993, which was within the range of values that most lobsters are nonmigrato9 and remain in for 3 unit studies (157 625), but higher than the the local area, since 1978 1,117 have been number collected in 2 unit studies (102 and 143).
recaptured more than 5 km t,,vay from Millstone Occurrence of larvae in entrainment samples Pt. (Table 11). Of these, several hundred lobsters coincided with the catch of berried females and were recaptured by lobstermen in The Race, a their egg development. Observations of the shape, deep water channel 10.5 km from MNPS between color and development of embryos indicated that 26 Monitoring Studies,1993
1
,x most hatching occurred during late May and June. )
As stated earlier, only a few berried females werc { y* I caught in July, indicating the completion of l Iw U ' hatching. Stage Ilarvac accounted for 949 of the 3 four larval stages collected during 1993 (Fig. 8). j* Similarly, Stage I larvae predominated in the g *c _ collections during previous 3-unit (38 90%) and 2- 1 3, q - unit studies (86 and 87G; Fig. 8). Stage 11 and 111
=
A 4 h q larvae were rarely collected in our entrainment f'"gNgN a _,s.4_n L a v .. o
- e .: .'
._Ng .
samples, and with the exception of the 1988 and 1992 collections, these larval stages have accounted for only 5% of the totallarvae collected since the
" N E ' " " " 50000C* ' ""
studies began in 1984 Only two Stage IV larvae j Fig. 8 Annual number or lotster lanae (Stage I IV) collected were collected during 1993, accounting for < 1G in samples of the MNPS discharges from 1984 to 1993. of the total larvae collected. Stage IV larvae comprised between 4 and 529 of the four larval TABLE 12. Delta mean denuty (number per 1000 m' 2 59 stages collected in previous studies (Fig. 8). Other Cl.) of lohler larvae collected in day and night entrainment researchers in southern New England found similar samples from 1984 to 1993. high variability in numbers and stage composition of lobster larvae (Bibb et al.1983; Fogarty 1983; Year Time Delta mean 95G Cl. et al. IM Wake M M8h of day densitya The A-mean density of lobster larvae collected 3 in 1993 night samples (1.168 per 10lX) m ) was 1984 Day 0.158 0 001 u.256 similar to the density in day samples (0.963/1000 Night 0.737 0.138-1.33" m'; Table 12). However, density of lobster larsac 1985 Day 0.390 -0 041-0 820 night samples had been significantly higher than Ndhi 0.620 u.290-0.951 day samples in four previous 3 unit study years (1986,1989,1990,1991; Table 12). The diel 1986 Day 0 324 0 0o3-0 5s5 variability observed in our studies was similar to Night 1 399" 0.556 2.242 what other researchers found througt.out the range 1987 Day 0 791 0 040 1.542 of lobsters. Positive phototaxis of Stage I larvae Nig'hi 0.667 02051.1;9 Was demonstrated in early laboratory studies by Templeman (1937,1939), which contrasts with 19sa Day 0127 0199 1653 results of more recent field surveys conducted in
- 4 Night 0 688 0271 1106 Canadian waters by Harding et a't. (1987). Their 1989 Day 0 158 0.087-0 229 work on Browns Bank, southwest of Nova Scotia.
Nigr t 1.403* 0 537 2.209 indicated that most Stage I larvac were collected between 15 and 30 m during the day and rarely 1990 Day 0.341 0 101-0.581 found below 10 m at night. Thermal gradients Night 1.I6f 0.569 1.765 were recently shown to innuence the vertical 1991 Day 0 287 0 131 0 442 inigration of lobster larvae, with all four stages Night 0.756' O.502-1.010 seeking the warm water above the thermocline regardless of time of day (Boudreau et al.1991). 1992 Day 1.299 0 043-2 555 Night 1369 0 530-2.209 The 1993 annual A mean density of lobster larvae collected in entrainment samples (1.081 per 1993 Day 09o3 -0.207 2.132 m) m') was the second highest value reported Nighi 1.168 -0 097 2.433 since the entrainment studies began in 1984 (3 unit 0.5251.334; 2-unit 0.409 and 0.504; Table 13). The 3 estimated number of lobster larvae entrained S gn f ni d if r nIe Elween day and mght densities 2-sample ng aler syWm was t-iesis (pc o 05). 389,767, which was within the range of entrained larvae reported in other 3 unit studies (2%,173-l Lobster Studies 27 1
TABt213. Annual mean density (number per 1000 m') or lobster larvae in entrainment samples during their season of occurrence and annual entrainment estimaies with 95% C.I. for MNPS from 1984 to 1993. Year Time period.- Number Mean Cooling included tarvae density
- 95W C.I. Vol.10* Estimate 959 Ct.
1984 2 t May-10Jul 102 0.409 0.184-0.635 189.4 '77.458 34,847-120,259 ? 1985 15May 10ul 142 0.504 0.258-0.749 255.1 128,550 65,806 191,040 1986* 14May-143ul 232 0.857 0.418-1.297 666.2 566,619 278,457-864,017 1987 18May-303un 184 0.943 0.274 1.613 423.8 399.608 116.111-683,529 1983 16May-1Aug 571 0.717 0.296-1.137 837.6 600,573 -247,935 952,372 1989 22May-283ut 237 0.701 0.358 1.044 562.8 394.518 201,3 0-587,556 , 1990 14May-303ul 280 0.748 0.436-1.060 779.1 582,738 339.671-825,805 1991 7May-22Jul 157 0.525 0.365-0.685 564.1 296.173 205.910-386,435 1992 19May.143ul 625 1.334 0.652-2.016 461.2 615.285 300.724 929.846 1993 24May-25Jun 218 1.081 0.273 1.889 360.6 389.767 98.433-081,101
- Mean densities are based on the delta mean (NUSCO 1988b and Penmngton 1983).
- tJnit 3 began commercial operation.
615,285), but higher than the 2 unit estimates of of LIS. Furthermore, Stage IV larvae exhibit - 77,458 and 128,550. Because total entrainment directional swimming behavior and can move tens estimates were based on cooling water volumes and of kilometers from the origin of hatching (Cobb et larval density, the highest entrainment estimates cl.1989; Rooney and Cobb 1991). Lund and were observed in 1986,1988, and 1990 wn:n all Stewart (1970) indicated that the large number of units operated at or near full power from May berried females found in western LIS (27G; Smith through July, and in 1992 when larval densities 1977) may be responsible for recruitment of Stage were highest. Since Unit 3 began operating, IV lanae in middle and eastern LIS. Stage IV entrainment estimates have been substantially larvae in our area may also originate from outside higher, because the cooling water demand of Unit Lis, as Cobb et al. (1989) observed Stage IV !arvae ; 3 alone is approximately the volume required by in Block Island Sound swimming in a northerly Units I and 2 combined. and easterly direction. Recently, commercial Impacts of entrainment of lobster larvae on lobstermen in western Lis reported a 50% decline lobster recruitment are difficult to assess due to in legal lobster abundance and the overall U.S. the unreliable estimates of larval and post-larval landings were 13% lower, which may lead to a survival rates (Phillips and Sastry 1980; Caddy and decline in our area iflocal recruitment depends on Campbell 1986; Cobb 1986; Blake 1991). In larval production in other areas. The decline in addition, researchers disagree on the source and legal lobster abundance is probably related to dispersion mechanism of lobster larvac. As a overfishing, and in western LIS the decline may be result, larval survival estimates are wide ranging. exacerbated by lobster kills due to disease ; In Canadian waters perhaps less than 10 of newly (Gaffkemin), eutrophication, and hypoxia of hatched larvae survive to the fourth stage (Scarratt bottom waters during the summer. i 1964,1973; Harding et al.1982), but in LIS more than 50% were estimated to survive through the Conclusions - 3 entire larval phase (Lund and Stewart 1970; Blake 1991). Most Stage Ilarvac entrained through the Since our studies began in 1978, fishing effort in - l plants cooling water system probably originate Connecticut waters has more than doubled. The ; from the berried females in the MNPS area. fishery is almost completely dependent on new because Stage I larvae are only in .the water animals molting into legal size; each year nearly all column for 310 5 days. It is unlikely that Stage IV the lobsters above the minimum legal size are originate from the local population because they removed by fishing. The total number of lobsters ; are in the water column for between 4 and 6 weeks caught and total CPUE in our study area reached and water currents would carry them to other areas record levels in 1992 and remained high during i 28 Monitoring Studies,1993 )
1993. However, legal lobster catches have Reihences Cited significantly declined since the NUSCO study began in 1978. Legal catches were expected to Aiken D.E.1973. Procedysis, setal deselopment. improve in 1993, after large numbers of lobsters, and molt prediction in the American lobster, observed to be just below legal size in the 1992 (Homarus americanus). J. Fish. Res. Board Can. , catches, molted to legal size. Instead, legal CPUE 30:1337-1344. declined during 1993 in contrast with recruitment Aiken D.E. 1980. Molting and growth. Pages patterns of presious study years when strong 91-163 in J.S. Cobb, and B.F. Phillips, eds. The recruit classes were followed by increased legal biology and management of lobsters, Vol.1, catches one year later. The observation that legal Academic Press, Inc., New York. catches did not increase in 1993 may be strong Aiken, D.E.,and S.L Waddy.1980. Reproductive indication that the lobster resource is currently biology. Pages 215-276 in J.S. Cobb, and B.F. overfished. Phillips, eds. The biology and management of Changes in the size sttucture, sex ratio and lobsters, Vol. I, Academic Press, Inc., New York. proportion of berried females oflocal lobsters, may Anthony, V.C., and J.F. Caddy.1o80. Proceedings be primarily due to increased fishing rates and to of the Canada-U.S. workshop on status of implementation of fishery regulations in 1984 assessment science for N.W. Atlantic lobster (escape vents) and 1988 (increased minimum size). (Homarus americamts) stocks (St. Andrews. The lower incidence of claw loss, and char.ges in N.B., Oct 24 26,1978). Can. Tech. Rep. Fish. recapture rates and size structure of tagged Aquat. Sci. 932.186 pp. ' lobsters caught in NUSCO and commercial traps Bibb, B.G., R.L Hersey, and R.A. Marcello, Jr. during 3-unit studies were attributed to the use of 1983. Distribution and abundance of lobster escape vents. The percentage of berried females larvae (Homarus americanus) in Block Island collected nearly doubled during 3-unit studies and Sound. NOAA Tech. Rep. NMFS was probably related ' to the increase in the SSRF-775:15-22. minimum legal size. Both of these regulations Blake, M.M. 1984. Annual progress report were implemented to improve lobster sursival and Conneeticut lobster investigations, appear to be effective. However, fishing effort January-December 1983. NOAA-NMFS Project (number of fishermen and traps and frequency of No. 3-374-R. 47 pp_ trap hauls) continues to increase and fishery Blake, M.M. 1988. Final Report Connecticut' managers question the stability of the resource lobster investigations January 1,1983-December under that kind of fishing pressure. 31, 1987. NOAA-NMFS Project No. 3-374.R. The density of lobster larvae was higher during 103 pp. 3-unit studies due to the higher percentage of Blake, M.M.1991. Connecticut lobster (Homams berried females. Estimated numbers of larvae americam<s) population recruitment studies entrained through the MNPS cooling water systems January 1, 1988-December 31, 1990. were also higher during 3 unit operation,in part NOAA NMFS Project No. 31J4. 87 pp. due to the higher cooling water demand of Unit 3. Blake, M.M., and E.M. Smith. 1984. A marine Higher larval entrainment may affect subsequent resources plan for the state of Connecticut. legallobster abundance, but quantification of this Connecticut Dept. of Environ. Protection, Mar. impact is difficult given the uncertainty of larval Fish. 244 pp. l origin and larval survival and recruitment rates to Boudreau, B., Y. Simard, and E. Bourget. 1991. legal size. Since lobsters require 4-5 years of Behavioural responses of the planktonic stages growth before they are vulnerable to capture, and of American lobster Homarus americanus to an additional 2 years of growth to reach legal size, thermal gradients, and ecological implications. a decline in local lobster abundance caused by Mar. Ecol. Prog. Ser. 76:13423. larval entrainment would not be apparent for Briggs, P.T., and F.M. Mushacke. 1979. The several years. Continued monitoring of lobsters American lobster in western long Island Sound. and lobster larvae will demonstrate the effects, if NY Fish Game J. 26 59-86. any, of 3-unit operation on the local lobster Briggs, P.T., and F.M. Mushacke. 1980. The -' population. American lobster and the pot fishery in the Lobster Studies 29
inshore waters off the south shore of Long Pages 97-142 in J.S. Cobb, and B.F. Phillips, eds. Island, New York. -NY Fish Game J. ' The biology and management oflobsters, Vol 11,~ 27:156 178. _ . Academic Press, Inc., New York. Brigt,s, P.T., and F.M. Mushacke. 1984. The Dow, R.L 1966. The use of biologicalc American lobster in western - Long Island environmental and economic data . to predict - Sound: Movement, growth and mortality. NY supply and to manage a selected marine Fish Game J. 31:21-37. resource. The Amer. Biol. Teacher 28:26-30. Caddy, J.F., and A. Campbell.~ 1986. Summary of Dow, R.L 1969. Cyclic and geographic trends in session 9: s u mma ry of research seawater temperature and abundance of recommendations. Can. J. Fish. Aquat. Sci. American lobster. Science 164:1060-1063. 43:2394-2396 Dow, R.L 1976. Yield trends of the American ' ' campbell, A.1982. Movements of tagged lobsters lobster resource with increased fishing effort. released off Port Maitland, Nova Scotia, Mar. Technol. Soc. 10:17-25. 4 1944-80. Can. Tech. Rep. Fish. Aquat. Sci. No. Ennis. O.P.1971. Lobster (Homarus americanus) . 1136. 41 pp. fishery and biology in Bonavista - Bay, Campbell, A.,and A.B. Stasko.1985. Movements Newfoundland. 1966-70. Fish. Mar. Serv. Tech. of tagged American lobsters, Homarus Rep. 289. 46 pp. americanus, off southwestern Nova . Scotia. Ennis, G.P. 1974. Observations on the lobster-Can. J. Fish. Aquat. Sci. 42:229-238. fishery in Newfoundland. Fish. Mar. Serv. Tech. , Campbell, A., and A.B. Stasko 1986. Movements Rep. 479. 21 pp. . of lobsters (Homarus americanus) tagged in the Ennis, G.P.1980. Size-maturhy relationships and Bay of Fundy, Canada. Mar. Biol. 92:393-404. related observations in ' Newfoundland ~ Cobb, J.S.1986. Summary of session 6: ecology of populations .of Ihe lobster . (Homarus population structures. Can. J. Fish. Aquat. Sci. americanus). Can. J.. Fish. Aquat. Sci. 43:2389-2390. 37:945-956. Cobb, J.S., D. Wang, R.A. Richards, and M.J. Ennis. G.P. 1984. Small-scale seasonal-Fogarty. 1986. Competition among lobsters movements of the American lobster, Homams and crabs and its possible effects in americanus. Trans. Am. Fish. Soc. I13:336-338. Narragansett Bay, Rhode Island. Pages 232 290 Fair, J.J., and B. Estrella. 1976. A study on the in G.S. Jamieson and N. Bourne, eds. North effects of sublegal escape vents on the catch of Pacific Workshop on stock assessment and lobster traps -in five . coastal f areas 1.of management of invertebrates. Can. Spec. Publ. Massachusetts. Unpublished manuscript, Mass. Fish. Aquat. Sci. 92. Div. Mar. Fish. 9 pp. Cobb, J.S., D. Wang, D.B. Campbell, and P. Flowers, J.M., and S.B. Saila.1972. An analysis of .? Rooney. 1989. Speed and direction of temperature effects on the inshore lobster , swimming by postlarvae of the American fishery. J. Fish. Res. Board Can. 29:1221-1225. lobster. Trans. Am. Fish. Soc. 118:82-86. Fogarty, M.J. 1983. Distribution and relative Cooper, R.A.1970. Retention of marks and their abundance of American lobster, A urus effects on growth, behavior and migrations of americanus larvae: New England investigations the American lobster, Homarus americanus, during 1974-79. NOAA Tech. Rep. NMFS Trans. Amer. Fish. Soc. 99:409-417. SSRF-775. 64 pp. Cooper, R.A., R.A. Clifford, and C.D. Newell. Fogarty, M.J.. and D.V.D. Borden. 1980. Effects 1975. Seasonal abundance of the American of trap venting on gear selectivity in the inshore lobster, Romarus americanus, in the Boothbay Rhode Island American lobster, Hamarus Region of Maine. Trans. Amer. Fish. Soc. americanus, fishery.- Fish. Bull., U.S. 77:925-933. 104:669-674. Fogarty, MJ., D.V.D. Borden. and H.J. Russell. Cooper, R.A., and J.R. Uzmann. 1971. 1980. Movements of tagged American lobster, Migrations and growth of deep-sea lobsters, Homarus americamis, off Rhode Island. Fish. ; Homarus americanus. Science 171:288-290. Bull., U.S. 78:771 780. Cooper, R.A., and J.R. Uzmann. 1980. Ecology Gilbert, R.O. 1987. Statistical methods for of juvenile and adult Romarus americanus, environmental pollution monitoring. Van 30 Monitoring Studies 1993 b
. _ _ _ _ . _- , _ _ _ _ . _ --_a ---t
Nostrand Reinhold Co., New York. 320 pp. Maine coast. Fish. Bull., U.S. 73:862-87L Harding, G.C.; W.P. Vass, and K.F. Drinkwater. Krouse, J.S., K.H. Kelly, D.B. Parkhurst Jr., G.A. ' 1982. Aspects of larval American lobster Robinson, B.C. Scully, and P.E. Thayer. 1993. (Homarus americanus) ecology in St. Georges Maine Department of Marine Resources Bay, Nova Scotia. Can. J. Fish, Aquat. Sci. Lobster Stock Assessment P.oject 3-1J-61-1. , 39:1117 1129. . Annual report April 1,1992 6 rough January 31. Harding, G.C., J.D. Pringle, W.P. Vas.i, S. Pearre 1993. 61 pp. Jr., and S.J. Smith.1987. Vertical distribution Kurata, H.1962. Studies on the age and growth and daily movement of larval lobsters Romams of Crustacea. Bull. Hokkaido Reg. Fish. Res. . amcricanus over Browns Bank, Nova Scotia. Lab. 24:1-115. Mar. Ecol. Prog. Ser. 49:29-41. Landers, D.F., Jr., and M.M. Blake. 1985. The Herrick, F.H. 1911. Natural history of the effect of escape vent regulation on the American American lobster. Bull. U.S. Bureau Fish. lobster, Homarus americanus, catch in castern 29:149-408. lang Island Sound, Connecticut. Trans. 41st Hollander, M., and D.A. Wolfe. 1013. Annual Northeast Fish Wild. Conf 9 pp. Ncnparametric statistical methods. John Wiley Lund, W. A., Jr., and L.L. Stewart. 1970. and Sons. New York. 503 pp. Abundance and distribution of larval lobsters. Hudon, C., and G. Lamarche. 1989. Niche Romarus americanus, off southern New England. segregation between American lobster Romarus Proc. Natl. Shellfish. Assoc. 60:40-49 americanus and rock crab Cancer irrorams. Lux, F.E., G.F. Kelly, and C.L. Wheeler. 1983. Mar. Ecol. Prog. Ser. 52:155 168. Distribution and abundance of larval lobsters Keser, M., D.F. Landers, Jr., and J.D. Morris. (Homarus americanus) in Buzzards Bay, 1983. Population characteristics of the Massachusetts, in 1976-79. NOAA Tech. Rep. American lobster, Romams americanus, in NMFS SSRF-775:29-33. castern Long Island Sound, Connecticut. Mauchline,J. ,1976. The Hiatt growth diagram for - NOAA Tech. Rep. NMFS SSRF-770. 7 pp. Crustacea. Mar, Biol. 35:79-84. " Krouse, J.S. 1973. Maturity, sex ratio, and size McConnaughey, R.A., and L.L Conquest. 1993. composition of the natural population of Trawl survey estimation using a comparatise American lobster, Homcms americanus, along approach based on lognormal theory.' Fish. the Maine coast. Fish. Bull., U.S. 71:165 173. Bull., U.S. 91:107 118. Krouse, J.S. 1976. Incidence of cull lobsters, McLeese, D.W., and D.G. Wilder. 1958. The Romarus americanus, in commercial and activity and catchability of the lobster (Homarus research catches off the Maine coast. Fish. americanus)in relation to temperature. J. Fish.- Bull., U.S. 74:719 724. Res. Board Can. 15:1345-1354. Krouse, J.S. 1978. Effectiveness of escape vent Miller R.J. 1989. Catchability of . American shape in traps for catching legal. sized lobster, Lobsters (Homarus americanus) and Rock Crabs Homarus americanus, and harvestable-sized (Cancer irroratus) by traps. Can. J. Fish. Aquat. crabs, Cancer borealis and Cancer irroratus. Sci. 46:16521657. Fish. Bull., U.S. 76:425-432. NMF4 (National Marine Fisheries Service).1993. Krouse. J.S. 1980. Summary of lobster, Homarus Report of the 16th Northeast Regional Stock americanus, tagging studies in American waters Assessment Workshop. Northeast Fish. Sci. (1898-1978). Can. Tech. Rep, Fish. Aquat. Sci. Cen. Ref. Doc. 93-18. NOAA/NMFS Northeast 932:135-140. Fisheries Science Center, Woods Hole, MA. Krouse, J.S. 1981. Movement, growth, and 118 pp. mortality of American lobsters, Homarus NUSCO (Northeast Utilities Service Company). americanus, tagged along the coast of Maine. 1982. Lobster Population Dynamics.A Review NOAA Tech. Rep. NMFS SSRF-747,12 pp. and Evaluation. Pages 1-32 in Monitoring the Krouse, J.S., and J.C. Thomas. 1975. Effects of marine environment of Long Island Sound at-trap selectivity and some population parameters Millstone Nuclear Power Station, Waterford, on the size composition of the American Connecticut. Resume 1968-1981. lobster Homarus americanus, catch along the NUSCO.1986. The effectiveness of the Millstone Lobster Studies . 31
-1 Unit -1 sluiceway _ in _ returning impinged Fish. Bull., U.S. 81:51-60.
organisms to Long Island Sound. Enclosure to Richards, R.A., and J.S. Cobb. 1987. Use of , letter D0ll85 dated May 27, 1986 from R.A. avoidance responses to keep spider crabs out of Reckert, NUSCO,10 S.J. Pac, Commissioner, traps for American lobsters. Trans. Amer. Fish. CTDEP 18 pp. Soc. I16:282-285. l NUSCO. 1987a. ' Lobster population dynamics. Rooney, P, and J.S. Cobb. 1991. Effects _ of time ! Pages 1-42 in Monitoring the marine of day, water temperature, and water velocity on . 1 cmironment of Long Island Sound at Millstone swimming by postlarvae of the . American J Nuclear Power Station Waterford, Connecticut. Lobster, Homarus americanus. Can. J. Fish.' ; Summary of studies prior to Unit 3 operation Aquat. Sci. 48:1944 1950. 1987. . Saila, S.B., and J.M. Flowers. 1968. Movements NUSCO.1987b. The effectiveness of the Unit 3 and behavio; of berried female lobsters '
- fish return system 1987. 20 pp. displaced frot offshore areas to Narragansett NUSCO. 1988a. The usage and estimation of Bay, Rhode Island. J. Cons. Int. Explor. Mer. j DELTA means. Pages 311-320 in Monitoring 31:342-351.
the marine environment of long Island Sound Scarratt, D.J.1964. Abundance and distribution , at Millstone Nuclear Power Station, Waterford, of lobster larvae (Homarus americanus) in Connecticut. Three-unit operational studies Northumberland Strait. J. Fish. Res. Board , 1986-1987. Can. 21:66168tL NUSCO. 198Sb. The effectiveness of the Scarratt, D.J.1970. Laboratory and field tests of-Millstone Unit 3 fish return system. Appendix modified sphyrion tags on lobsters,(Humarus I to Enclosure 3 to letter D01830 dated January amencanus). J. Fish. Res. Board Can. 29, 1988 from EJ. Mroczka, NUSCO, to L. 27:257 264. Carothers, Commissioner, CTDEP. 21 pp. Scarratt, D.J. 1973. Abundance, sursival, and , NUSCO. 1988c. Hydrothermal Studies. Pages vertical and diurnal distribution of lobster larvae 323-355 in Monitoring the marine environment in Northumberland Strait' 1%2-63, and their - of I.ong Island Sound at Millstone Nuclear relationships with commercial stocks. J. Fish. Power Station, Waterford, Connecticut. Res. Board Can. 30:1819-1824. Three-unit operational studies 1986 1987. Scarratt, D.J., and P.F. Elson. ' 1965. Preliminary NUSCO. 1993. Lobster studies. Pages 7 32 in trials of a tag for salmon and lobsters. J. Fish. Monitoring the marine environment of Long Res. Board Can. 22:421-423. , Island Sound at Millstone Nuclear Power Sen, P.K. 1968. Estimates of the regression Station,Waterford, Connecticut. Annualreport coefficient based on Kendall's tau. J.' Am. Stat. 1992. Assoc. 63:1379-1389. > Pecci, K.J., R.A. Cooper, C.D. Newell, R.A. Skud, B.E., and H.C. Perkins. 1969. Size Clifford, and R.J. Smolowitz. 1978. Ghost composition, sex ratio and size at maturity of fishing of vented and unvented lobster, offshore northern lobsters. U.S. Fish Wildl. , Romarus americanus, traps. Mar. Fish. Rev. Spec. Sci. Rep. Fish. 598.10 pp. 409-43. . Smith, E.M. 1977. Some aspects of catch / effort, Pennington, M. 1983. Efficient estimators of biology, and the economics of the Long Island abundance, for fish plankton surveys. lobster fishery during _1976. NOAA.NMFS, Biometrics 39:281286. Commer. Fish. Res. Dev. Act Project No. Phillips, B.F., and A.N. Sastry. 1980. Larval 3-253 R-1. 97 pp. ecology. Pages 1157 in J.S. Cobb, and B.F. Smith, E.M., E.C. Mariani, A.P. Petrillo, L.A. Phillips, eds. The biology and management of Gunn, and M.S. Alexander. 1989. Principal - Lobsters, Vol 11, Academic Press, Inc., New fisheries of Long Island Sound, 1961-1985. York. Connecticut Dept. ' Environ. Prot., Div, of Richards, R.A., J.S. Cobb, and M.J. Fogarty. 1983. Conservation and Preservation, Bureau of Effects of behavioral interactions on the Fisheries, Mar. Fish. Prog. . catchability of American lobster,' Homarus Snedecor, G.W., and . W.C. Cochran. 1967. americanus, and two species of Cancer crab. Statisticsl methods. The lowa State University 32 Monitoring Studies.1993 i ______________.:1
I Press, Ames, IA. 593 pp. Stewart, LL 1972. The seasonal movements, population dynamics and ecology of the lobster, , Romarus americanus (Milne. Edwards), off Ram Island, Connecticut. Ph.D. Thesis, University of , Connecticut, Storrs, CT.112 pp. Templeman, W. 1935. Local differences in the body proportions of the lobster, Homarus americanus. . J. Biol. Board Can. 1:213 226. I Templeman, W. 1936. Local differences in the life history of the lobster (Homams americanus) . on the coast of the maritime provinces of Canada. J. Biol. Board Can. 2:41-88. Templeman, W.1937. Habits and distribution of , larval lobsters (Homams americanus). J. Biol. Board Can. 3:343 347. ' Templeman, W.1939. Investigations into the life history of the lobster (Homarus americanus) on ; the west coast of Newfoundland. 1938. . Newfoundland Dep. Nat. Resour. Res. Bull. (Fish) 7. 52 pp. Templeman, W. 1940. Lobster tagging on the ' west coast of Newfoundland 1938. . Newfoundland Dep. Nat. Resour. Res. Bull. I (Fish) 8.16 pp. Thomas,J.C.1973. An analysis of the commercial lobster (Homams americanus) fishery along the coast of Maine August 1966 through December 1970. NOAA.NMFS Tech. Rept. SSRF-667. 57 PP- r Uzmann,'J.R., R.A. Cooper, and K.J. Pccci.1977. Migrations and dispersion of tagged American ' lobsters, Homarus americanus, on the southern New England Continental Shelf. NOAA Tech. Rep. NMFS SSRF-705. 92 pp. Wilder, D.G. 1953. The growth rate of the American lobster (Romams americanus). J. Fish. Res. Board Can. 10:371-412 ' Wilder, D.O. 1%3. Movements, growth and . survival of marked and tagged lobsters liberated in Egmont Bay, Prince Edward Island. J. Fish. , Res. Board Can. 20:305 318 - Wilder. D.G., and R.C. Murray.1958. Do lobsters move . offshore and. onshore in the fall and { spring? Fish. Res. Board Can. Atl. Prog. Rep.
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[ Ecigrass Introduction the natural senescence of plants in late summer and early autumn. l.ocal residents attributed the Ecigrass (Zosicra marina L) is the predominant die off of celgrass to the operation of Mi!! stone marine flowering plant in the northern hemisphere. Unit 1. Northeast Utilities initiated studies in 1973 to address these concerns; the studies It has colonized estuaries and lagoons of temperate and warm boreal coasts in the Atlantic and Pacific included mapping of celgrass beds in Jordan Cove Populations of this and measurement of environmental (e.g., water Oceans (Setchell 1935). species have successfully adapted to wide ranges of temperature and sediment characteristics) and t I temperature, salinity and water depth (Osterhout celgrass population parameters (e.g., shoot lengths 1917; Setchell 1929; Uphof 1941; Burkholder and and reproductive status) (Klotz and Knight 1973; Doheny 1968; Dillon 1971; Thayer et al.1984) Knight and Lawton 1974). These studies found no 1 Although few animal species consume the plant relationship between MNPS operation and. the l directly, eelgrass provides large quantities of errpy phenology of eclgrass populations. In addition, L and nutrients to consumers through the al hydrographic and hydrothermal studies indicated food chain. Besides providing habitat for loper that the thermal plume of Millstone Unit I did not j trophic level fish and crustacean consumcrs, reach the eclgrass populations in Jordan Cose or ! celgrass beds have physical, chemical and biological the Niantic River (VAST 1972; NUSCO 1979). effects on coastal ecosystems. These include: wave The present study was initiated in 1985 following the prediction that the 3 unit thermal plume would action and water movement reduction (Fonseca et al.1982) and hence prevention of erosion; trapping extend into Jordan Cove (ENDECO 1977). l and binding of sediments (Scoffin 1970) and Throughout the range of celgrass, researchers base organic detritus (Walker and McComb 1985); demonstrated that high water temperature affects provision of surfaces for colonization by epiphytes populations by reducing growth rate, lowermg (Harlin 1975); high rates of production (Hillman resistance to disease, and reducing the production et al.1989); contribution of calcium carbonate to and germination of seeds (Butkholder and Doheny sediments via epiphyte decomposition (Walker and 1968; Phillips 1974,1980; Orth and Moore 1983). Woelkerling 1988); and nutrient trapping and The objectives of the presem study are to identify recycling (Hemminga et al.1991). These functions temporal patterns of celgrass ' distribution, were interrupted when the
- Wasting Disease" of abundance and reproduction and to determine the the early 1930s destroyed most of celgrass extent to which these patterns may be affected by populations in castern North America and western natural variability or by MNPS operation.
Europe (Tutin 1942; Rasmussen 1973, 1977). Following the destruction of these populations, Materials and Methods increased wave scour and changes in current patterns caused shoreline erosion, and declines in Three celgrass study sites in the vicinity of abundance of many animal species, including MNPS were sampled during 1993 (White Point-commercially important fishes and lobster were WP, Jordan Cove-JC, Niantic River NR) (Fig. lj. observed (Stauffer 1937; Dexter 1947; Milne and The WP and JC stations are located 1.6 km and Milne 1951; Orth 1973,1977; Rasmussen 1973, 0.5 km east of the power plants discharge, 1977; Thayer et al.1975; Zieman 1982). respectively, and are within the area potentially Recovery of castern North Atlantic celgrass influenced by the 3-unit thermal plume (ENDECO populations began in the late 1950s, and by the 1977; NUSCO 1988). The NR site, located about early 1970s populations in the Niantic River were 3 km from Millstone Point, is a control station in so dense that dynamite was used to clear areas an area unaffected by power plant operation (Fig. through eelgrass beds to maintain water circulation 1). Water depths (measured below mean low (Klotz and Knight 1973). Eelgrass populations water) were 2.5 m at WP,1.5 m at NR and 1.1 m were also dense in the vicinity of Millstone atJC. . Nuclear Power Station (MNPS), and large amoums The WP and JC sites have been sampled since of celgrass washed ashore at local beaches due to 1985. The NR site has been relocated several Eclgrass 37
)
t Nionti Rever North Ikm 0: 1' mi 23 Neontic Boy pg
- x JC 4 White Po.nt WP Block Point
( Fig. t. Map of the Mdistone Point area showing the location of celgrass samphng stations. JC= Jordan Cose p), NR=Niantic Rwer (t = sampled 1985 June 1966 and 1993. 2= sampled July 19% september 19% 3-sampled 1901992, was sampled m 1993. but no celgrass was present). WP= White Pomt p). times . since 1985 due to shifts in eclgrass through September 1993, the period of maximum abundance patterns in the Niantic River. The standing stock and plant density. At each station, original sampling site (#1, also designated 'old' in 16 samples were collected by SCUBA divers this and previous reports), located midway between randomly tossing a quadrat (25x25 cm,0.0625 m2) Camp Weicker and the navigation channel (Fig.1), within a 10 m radius of the station marker. The was sampled throughout 1985 and in June 1986. upright shoots from plants within each quadrat A substantial population decline at site #1 was were harvested, placed in a 0.333 mm mesh bag, noted in July 1986, so another NR sampling site and taken to the laboratory for processing. A 3.5 was established (#2) 50 m to the south, nearer the em diameter x 5 cm deep core was taken together navigation channel. Site #2 was sampled for the with eclgrass samples for analysis of sedimentary remainder of the 1986 season; however, by characteristics at each station. Temperature in September 1986, the eclgrass populatfan at this Jordan Cove was measured by submerging a self. site had also disappeared. In June 1987, a new NR contained thermistor recorder. Continuous sampling site was established at the nearest viable teraperature measurements have been. recorded population located in the lower river (#3). A there since 1991. Temperatures reported herein slower, but steady, decline of the eclgrass cover the period from June 1 through September population at site #3 has been documented since 30, when additional temperature increases above 1987 (NUSCO 1993), and by June 1993, no ambient from the 3-unit operation of MNPS could , celgrass shoots were observed at this site. In be most detrimental to eclgrass in Jordan Cove.- J contrast, an extensive recovery of the celgrass All shoots collecica were counted in the population at the old NR site (#1) was noted in laboratory and the longest blade of each shoot (up 1993, and NR samples were again taken at this to 20 plants per sample) was measured to the station during the 1993 season (June-September). nearest centimeter. The number of reproductive Samples were collected monthly from June shoots in each sample was recorded and used to .j 38 Monitoring Studies,1993 l l I 1 1
36 I
/N p 5
33 \
/
Discharge; , ,/ i, 30 'y ,e sfj / g . j '
- , i o
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- i, i
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E* Jordan Cove
' I h 2'- ,..,,,.... - .
y is. ,',' ' ~ < Intake
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!5 ! ! !
d3 36886660 0 000 i !!!!
;;;;;h ! ! ! i iii i i i i i ;
3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Fig. 2. Daily average water temperature at the Jordan Cove celgrats station and al the MNPS intake and dacharge June 1993 through ' September 1993. Units 1. 2. and 3 operation are also indicated for the r.ame period estimate the percentage of reproductive shoots in is highest during the summer (Roman and Able the population. Shoots were rinsed in freshwater 1988). Mean sediment grain size and silt / clay J to remove invertebrates and at the same time, all content were determined using the dry sieving epiphytes were removed. Because the presence of method (Folk 1974). Sediment samples .were , epiphytes on eclgrass shoots uns minimal heated to 500 *C for 24 h to determine organic throughout the study, epiphyte weights were not content, estimated as the difference between dry- ' recorded. Eelgrass standing stock was estimated as weight and ash-weight. Both silt / clay and organic _ l the weight of the shoots taken from each quadral ~ content %cre recorded as a percentage of the total "; From 1985101987, shoots were weighed, then sediment sample weight. Additional sediment dried in an oven at 80 *C to a constant weight. samples collected at the NR site #3 were analyzed Because dry-weights closely correlated with wet. to evaluate whether any sediment changes noted weights (r 2=0.94-0.99), dry weights from 1988 to could be connected to the decline of eclgrass at 1993 were estimated from the wet-weight / dry- this site. weight relationship and presented in this report as grams dry weight /m2 (g/m 2). Nonparametric Results methods were used to examine trends in the time series of eclgrass shoot density and standing stock. The distribution free, Mann-Kendall test pah , (Hollander and Wolfe 1973) was used to determine whether the time series of mean monthly standing Water temperatures at the JC celgrass site have stock biomass or shoot density exhibited significant been measured with continuous temperature trends. The slope of the trend, when significant, recorders from May 1991 through December 1993. was estimated by Sen's estimator of the slope (Sen Daily average water temperatures during 1993 1968). Ecigrass shoot length was not statistically (June through September) at JC and the MNPS analyzed because growth occurs at the base of the intake and discharge are shown in Figure 2. shoot (from a basal meristem) and tips Temperatures at JC and the intakes ranged continuously erode,and because leaf turnover rate between 13.4 Cand 23.5*Cand between 13.5 Cand i Eelgrass . 39
a
,, xnann covf E, 40 0 h soo d so o E io v \ 3 to ..%:R* n s..g.?,%v.~<.% g, % f .Dd Yt os V V +
f o6 k a e4 1
,, pv .__ : - - A - . -h oo........,__J..__... J.,....,
MANTC RfVfD $'TE j i e
- f *o.o a I' f so.o s- -g
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^l as.
- ,, \. ,,l i
o2 -
,b a ao A, 485 Joo M6 467 847 J80 ma6 J84 Ada Jso ago J., ali JB2 a92 483 A93 gg kaNnC RWD $r'f J 3 7
- eo.o h no ?
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lt\s
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v = d as y as { 04 h 88 N h ^w,% k/ g .% 5 so as as, me aa6 41 as, as asa Jos us ao aeo ai asi m aez as a.3 Mo wH;T 0N E .c o h soo t to o ?A i A E ic e. , [ N , **/ i . ~. ./
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{ ,, .....,-+.*s...~....-.-.......,,. [ oo f o4 {a oa l
-. =__ _.. :%_ __ __/%
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Fig. 3. Mean grain Sire (a), organic content (*) and sih/ clay content (o) of sediments at Millstone ee! grass stations at Jordan Covec Niantic Rrver (Site #1 and Site #3) and White Point sampled dunng the period June September from 198$ through 1993. 40 Monitoring Studies,1993
V
~
2 TADI.E 1. Annual and monthly average shoot density (no/m ),2 length (em) and dry weight standing stock (gm/m ) for celgrass sampled near MNPs dunng the June to september period. ANNt f Al. MEANS ,},,992 1985 1986 1987 1988 1989 1990 1991 1992 1993 .Jun Jul - Aug sept
? $bont Density
, Jordan Cove 572 713 542 468 411 338 603 630 484 493 510 516 417 Niantic River 413 72 294 307 240 225 249 233 385 607 387 350 190 - , White Point 286 218 227 161 335 185 242 204 310 403 313 368 156 Shnnt t_ength Jordan Cove 57 57 77 75 74 38 48 53 54 65 60 47 43 Niantic River 50 39 81 88 94 73 51 48 58 68 64 57 31 White Point 107 116 12n 86 110 106 87 72 107 104 107 121 82 Standing Stock Jordan Cove 243 276 258 2.M 202 105 169 210 100 211 179 169 81 Niantic River 156 32 184 181 183 143 81 79 125 177 147 143 .31 , White Point 265 260 201 90 236 180 148 -110 275 358 209 388 85 22.2*C, respectively, and were slightly warmer than Values for all sediment parameters measured at - those measured during the 1992 study (JC range NR site #3 in 1993 were also within the range of 13.1-22.5'C and intakes ll.9 20.4*C). Daily previous years (1987-1992). Mean grain size in average water temperature at JC was up to 2.5 *C 1993 ranged between 0.12 and 0.23 mm compared warmer than at the intakes. to 0.10 - 0.28 mm during the previous six years. The ranges in silt / clay and organic content in 1993 , Sediments were 5.121.39 .and 2.3-7.0E respectively,- compared to 2.6-36.0% and 1.415.5% respectively Sediment mean grain size, silt / clay and organic during 1987-1992. content for the months June through September from 1985 to 1993 are presented in Figure 3. Shoot Density Mean grain size at JC and WP during 1993 ranged from 0.21 to 0.24 mm and from 0.12 to 0.25 mm, Spatial patterns of eclgrass shoot density among respectively. Silt / clay content at JC (3.2-9.9%) was sampling stations during 1993 (June-Sept.) were lower than at WP (6.410.7%). Sediment organic similar to results from 1985 to 1992. Average content at JC was also slightly lower (1.2;2.0%) shoot density during 1993 was highest at JC (484 than at WP (1.7-3.0). With the exception of the shoots /m2 ) and lowest at WP (310 shoots /m ; Table high mean grain size value at WP in June, all of . 1). The nine year time-series (1985-1993) of shoot - a the above 1993 values at JC and WP were within density at JC and WP showed noAignificant trends the range of previous years (1985-1992). . (Fig. 4). The average density at NR' #1 (385 Mean grain size at NR site #1 in 1993 ranged 2 shoots /m ) was similar to that in 1985 (413 from 0.12 to 0.37 mm. Organic and silt / clay 2 shoots /m ), but annual trend analysis was not content were 1.7-6.4% and 6.5-15% respectively. performed on NR #1 shoot- densities, due to Values for all sediment parameters observed in insufficient data for that site. . 1993 at NR site #1 were within the range of Monthly shoot densities were highest in June at previous years (1985,1990-92). NR #1 (607 shoots /m 2) and WP (403 shoots /m2 ), Ecigrass 41 b
k[ , l
'l s2m ,,33 ,,,u ,, in, #,0,^7, 9,,o ,,,, , ,,2 ,m l
. ion I
1 **
!~
I-llI I{ i fli oii ll I ill I i { l ,
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o
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E 800
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( l il l{gt II III, }}4 { 0 i///////fJfJfJfJfJ 2 Fig.4. Mean numberof eclgrass shoots per m
- 957c C.I. at Millstone celgrass stahons sampled dunng the period June. September from 1985 through 1993.
and highest in August at JC (516 shoots /m 2; Fig. 4). Shoot densities in June, July and August 1993 Yearly (1985-1993) and 1993 monthly (June-2 at NR (607,387 and 350 shoots /m , respectively). September) average shoot lengths are presented in and ' at WP (403, 313 and 368 shoots /m 2, Table 1. During 1993, shoots were longest at WP ' , respectively) were, for each station, among the (107 cm), shortest at JC (54 cm) and intermediate:.- - highest observed for those same months over the at NR #1 (58 cm). The 1993 average shoot length-entire study period (Fig. 4).- The 1993 monthly values at JC and WP stations were within the 2 l densities at JC (417 516 shoots /m ) were ranges of values from previous years, (43-65 cm ; comparab!c to those from other years. and 82-121 cm, respectively). The 1993 shoot length average at NR #1 (58 cm) was within the
- overall range of all annual means in the Niantic ~ '
42 Monitoring Studies,1993 1 r
JORDAN CCVE 7" iss5 seu tes t ises isas tsso tie s tse2 essa en .s i30 its 'l i g in 1 ,, O f///f///f///////// mace evtp 2* ins ... in, som in . .w .... in .n3
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' ll 4
g t .I tI g, no s,
- 25 1
f///fJfff#f/////// Fig. $. Mean shoot length (cm) 2 95% Cl. at Millstone celgrass stations sampled during the period June Septemtier from 1983 through 1993. River since 1985 (39-94 cm), and was wry similar - Standing Stock to the 1985 average (50 cm), when 1: tis site was L _ last sampled. Eelgrass standing stock during 1993 was highest Monthly shoot lengths in 1993 at JC and NR #1 at WP (275 g/m2) followed by JC (160 g/m 2) and . > declined from June (65 and 68 cm,' respectively) _ NR (125 g/m 2; Table 1). ' Annual mean standing. through September (43 and 31 cm, respectively; stock at WP during 1993 was the highest recorded Fig. 5); shoot length at WP increased from 104 cm to date (previous range,90-265 g/m'), but the 1993
' in June to 121 cm in August, then declined to 83 mean standing stock at JC was the second lowest cm in September. reported since 1985 (previous range,105 276 g/m2 ). i The 1993 standing stock at NR'#1 (125 g/m 2) was slightly lower than in 1985 (156 g/m2 ), but within Eelgrass. 43
- I
r Y JO@AN CCVC
- i$ ie in: # ,a .w. im mi ina ma aco r
_JM e 3* hm f ' f 5- i I j l So
) i{} l i 0-
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_JM T, m 2$0
!= 'l 5 iso
{ { { W l fj { ff kji f g f/f/f/f///f/f/f/f/
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_* f
', m 250 l m.
Em
; il g i L1 ;
e f/////f///f///f/f/ 2 fig. 6. Mean dry weight (grams, per m ) 2 95% Cl. at Milhtone celgrass sianons sampled dunng the penod June-September from 1985 through 1993. the range of annual means at NR #3 from 1987- (1993) at NR and JC were within the raage of 1992. Trend analysis indicated that standing stocks monthly means reported since 1985 (Fig. 6). The had significantly declined since 1986 at JC September 1993 mean at NR (although within the (slope =.3.180, p<0.002). There was no significant range of previous years) was among the lowest trend in standing stock at WP during the nine year reported during the study; the September _1993 (19851993) period. Trend analysis was not mean at JC was also among the lowest standing performed on the NR data, due to frequent station - stock measurements made at this site in the last relocation. nine years. In contrast,1993 June, July and Standing stocks in 1993 were highest in June at August monthly means at WP were among the 2 JC (211 g/m ) and NR (177 g/m2 ) and highest in highest reported at that site to date (Fig. 6). August at WP (388 g/m2 ) (Table 1). Monthly However. September standing stock at WP was mean standing stocks for June. July and August among the lowest reported at this site. 44 Monitoring Studies,1993
l
-l l
')
I TABLE 2. Number of reproductwe shoots, total number of shoots and percentage of reproductne shoots at celgrass sampling stations j from June 1985 through September 1993. ) 1 1 Annual June July August September
** % # Total' 4 # Total %
- Total ek #- Total 9 Jordan Cove 1985 44 1.9 10 561 1.8 23 591 3.9 11 514 2.1 0 622 0.0 1986 70 2.5 23 756 3.0 21 585 3.6 13 1046 1.2 13 . 464' 2.8 1987 72 3.3 18 581 3.1 24 537 4.5 19 496 3.8 11 555 2.0 '
1988 58 3.1 20 469 4.3 11 502 2.2 2 415- 0.5 25 487 5.1 1989 30 1.8 lb 534 3.0 12 526 2.3 2 356 0.6 0 228 0.0 1990 9 0.7 2 167 1.2 7 365 1.9 0 395 0.0 0 424 0.0 . 1991 24 10 14 448 3.1 10 647 1.5 0 654 00 0 662 0.0 1992 17 0.7 9 558 1.6 8 643 1.2 0 708 00 0 611 0.0 1993 93 4.8 56 493 11.4 36 510 7.1 1 516 < 0.1 0 417 0.0 Niantic River 1985 53 3.2 33 414 8.0 19 308 6.2 1 398 0.3 - 0 532 0.0 1986 15 5.3 1 3 33.3 14 170 8.2 0 95 0.0 0 18 0.0 - 1987 21 1.8 4 401 1.0 11 242 4.5 6 239 2.5 0- 294' O0 1988 44 3.6 19 356 5.3 ' 17 309 5.5 0 290 0.0 -8 273 2.9 1989 68 7.1 36 333 10.8 21 28H 7.3 11 187 5.9 0 150'. 0.0 1990 53 5.9 19 225 8.4 32 20o 12.0 2 189 1.1 0 218 0.0 1991 12 1.2 5 197 2.5 7 27o 2.5 0 290 0.0 0 227 0.0 1992 5 0.5 1 229 0.4 4 442 1.0 0 181 0.0 0 81 ' 0.0 1993 134 8.7 94 607 15.4 38 387 9.8 350 . < 0.1 0 196 0.0 White Point 1985 27 2.4 8 394 2.0 17 290 5.9 2 222 0.9 0 238 0.0 1986 79 - 9.1 51 293 17.4 14 161 8.7 6 234 26 8 182 4.4 1987 53 5.8 20 305 6.6 12 238 5.0 13 180 7.2 - 8 184 4.3 1938 30 4.7 3 186 16 13 161 8.1 5 133 3.8 9 104 5.5 1989 63 4.7 31 461 6.7 32 480 6.7 0 194 0.0 0 204 0.0 1990 77 10.4 47 199 23 0 2$ 212 11.8 5 186 2.7 0 144. ' U.c 1991 28 29 16 441 3.6 12 308 39 0 112 0.0 0 105 0.0 1992 4 04 1 270 < 0.1 3 194 1.5 0 195 00 0 ' 155 0.0 1993 4R 39 20 40'4 50 17 313 $4 11 W TO 0 156 00
- Total number of reproductive shoots.
b Total number of shoots (vegetative + reproductive). Reproductive Shoots WP. No reproductive shoots were collected at any station in September. Annual reproductive shoot Percentage of reproductive eclgrass shoots in percentages in 1993 were the highest values 1993 was highest in June at JC (11.4%) and NR observed since 1985 at JC (4.8G) and all NR sites (15.4%) and highest in July at WP (5.4%) (Table (8.7G). The 1993 value at WP (3.9G) was within 2). Percentage of reproductive shoots declined by the range of previous years (0.410.4%). August to <0.1% at JC and NR and to 3.0% at Eelgrass 45
5 k Discussion plants through germination of seeds transported - from healthy beds at the mouth of the river or in Density, length and standing stock of eclgrass Niantic Bay, and the subsequent vegetative shoots were examined during 1993 as part of a rhizome propagation. Although celgrass meadows long-term sampling program to assess whether any persist mainly by vegetative growth (Tomlinson changes in eclgrass populations have resulted from 1974), seed production and dispersal are important i
- 3. unit operation at Millstone Nuclear Power mechanisms for maintenance of a healthy Station At WP, no significant trends were evident p pulation, and are the only recolonization in the nine year time-series of plant density or mechanisms. Such patterns of recolonization were standing stock since 1985. In 1993, the WP study documented in the Chesapeake Bay (Orth 1976; parameters (i.e. - shoot length, percentage of Orth and Moore 1981,1983,1986);'as long as reproductive shoots and sediment characteristics) nearby populations remain healthy, and a source of were within the ranges of previous years. No long. seeds (e.g., at the re-established NR #1), il_is term changes, either power plant-induced or reasonable to expect similar recolonization in the ,
natural, have been identified with this population. lower Niantic River. Continued monitoring will L Niantic River celgrass populations are not pr vide information concerning celgrass exposed to the MNPS cffluent. Therefore, factors populations at these sites. Other than the effluent discharge were responsible In Jordan Cove, density, growth and standing for the climinations of populations at NR #1 and stock of celgrass shoots were higher during the - NR #2 in 1986 and early 1987, and the gradual first year of 3. unit operation (1986), followed by a loss of plants at NR #3 from 1987 to 1993. general decline from 1987 to 1990; in recent years, Eelgrass populations throughout the North these population parameters .have ' exhibited j Atlantic are characterized by high variability and considerable recovery. Jordan Covc is shallow,and fluctuations in abundance. Therefore, the eclgrass has large sand flats that are exposed to heating in population losses in the Niantic River are not summer, and freezing in. winter. As a result,~ considered to be merely a local phenomenon, but natural fluctuations in water temperature create a rather, are examples of such large-scale variability more stressful environment in Jordan Cove than at - in population parameters. Loss of eclgrass has White Point. been attributed to a variety of causes, ranging from The importance of temperature in regulating natural, e.g., ' wasting disease' (den Hartog 1987), eclgrass growth and development was first stressed severe storms (Patriguin 1975) to human activities, by Setchell (1929). It was later shown that. celgrass e.g. eutrophication (Bulthuis 1983; Orth and is sensitive to small temperat ure variations (Thayer Moore 1983; Cambridge and McComb 1984; et al.1984). Eelgrass plants do not produce seeds. Neverauskas 1985; Burkholder 1993), land at temperatures above 15-20 *C (Burkholder and - reclamation, or changes in near-shore land use Doheny 1968; Orth and Moore 1983). Higher (Kemp et al.1983). The disappearance of eclgrass water temperatures, e.g., from heated effluents of ' from the Niantic River in the late 1980s was power plants. could eliminate ccigrass from nearby attributed to a decline in water quality and the areas (Phillips 1974; Thayer et al.1984). The high presence of Labyrinthula (Short 1988), b'ut none of annual percentage of reproductive plants at JC these factors were implicated in the recent loss of during 1993 suggests that temperature increases plants from the lower river (NR #3). Instead, from 3-unit operation did r ot affect the their loss was associated with a heasy Myri/us set in reproductive cycle at this site. Studies of another 1991, which may have aided in uprooting, scagrass, Thn/assia, in Florida (Roessler and smothering or reducing light availability to plants. Zieman 1969; Wood et al.1969; ~Zieman 1970;' Recovery of the eclgrass population at NR #1, Roessler ~1971) and of Sportina altermporn in , firrt observed in 1989 and continuing through Maine (Keser et al.1978), showed a significant . 1993, was a relatively quick process. Others ha've decline in abundance of these plants in the vicinity suggested that recolonization on a global scale can of p wer plant effluents.- Elevated water - ,: take from 80-200 years (Clark and Kirkman 1989). temperatures increased respiration beyond levels l The apparent full recovery of the NR #1 that could be supported by plant photosynthesis. population is attributed to recruitment of new Recognizing that eclgrass meadows are among the E 46 Monitoring Studies,1993
most productive of marine systems (Marm 1973; den Hartog in Western Port, Victoria, Australia. McRoy and McMillan 1977; Zieman and Wetzel J. Exp. Mar. Biol. Ecol. 67:91 103. 1980) and act to stabilize sediments (Wood et al. Burkholder, P.R., and T.E. Doheny. 1968. The 1%9; Zieman 1972; Orth 1977), changes in biology of eclgrass. Contribution No. 3. Dept. eclgrass abundance at Jordan Cove could also Conservation and Waterways, Town' of affect the movement of sediments and species Hempstead, long Island. Contribution No. abundance of associated infaunal communities. 1227 Lamont Geological Observatory, Palisades, Further recognizing the importance of water New York.120 pp. , temperature in regulating celgrass populations, and Burkholder,J.1993. Botanist Investigates impact that the thermal plume resulting from 3-unit of Nitrate on Seagrasses. Coastlines 3:6.' , operation was predicted to extend into Jordan Cambridge. M.L. and A.J. McComb. 1984. The Cove (NUSCO 1988), the JC celgrass station has loss of seagrass from Cockburn Sound, Western been closely monitored for the past nine years. To Australia. l. The time course and magnitude of 3 date, the temperature extremes at this site appear seagrass decline in relation to industrial to be more related to insolation of the shallow- development. Aquat. Bm 20:229-243. water sand flats than to incursion of the thermal Clark, S., and H. Kirkman. 1989. Scagrass plume. However, when eclgrass plants are near stabilhy and dynamics. A.W.D. Larkum, A.J. their physiological li.mits, even a slight increase McComb and S.A. Shepherd (eds). Pages 304-above ambient temperature could be detrimental. 345 in Seagrasses: A Treatise on the Biology of Further monitoring at various levels of power Seagrasses with Special Reference to the plant operation, will allow determination of the Australian Region. Elsevier. North Holland. effects of temperature on the JC eclgrass den Hartog. C.1987.
- Wasting Disease" and other population, and the extent to which MNPS affects dynamic phenomena in Zostera beds. Aquat.
those temperatures. Bot. 27:314. Dexter, R.W. 1947. The marine communities of Conclusions a tidal inlet at Cape Ann, Massachusetts: A study in bio-ecology. Ecol. Monogr. 17:261-294.' Eelgrass population parameters and sediment Dillon, C.R. _1971. A comparative study of the , characteristics. sampled during 1993,were generally primary productivity of estuarine phytoplankton consistent with those sampled since 1985. At WP, and macrobenthic plants. Ph.D. Dissertation'. most parameters in 1993 were within the range of Univ. North Carolina, Chapel Hill.112 pp, previous years, and none appear to be influenced ENDECO (Environmental Devices Corporation). by MNpS operation. At NR, wide Ductuations of 1977. Postoperational Units 1 and 2, abundance have occurred, including localized preoperational Unit 3 hydrothermal survey of climination of plants from NR #1 (1986-1987). the Millstone Power Station. Rpt. to Northeast , from NR #2 (1987), and from NR #3 (1987-1993). Utilities Service Co. However, in recent years NR #1 has been Folk, D.1974. Petrology of Sedimentary Rocks. - recolonized, and the celgrass population apparently Hempshill Pub. Co., Austin, Texas. ' 192 pp. recovered completely. These Ductuations were Fonseca, M.S., J.S. Fisher, J.C. Zieman and G.W. related to factors other than MNPS operation. At Thayer. 1982. Innuence of scagrass Zostcra JC, changes in celgrass abundance may be related marina L on current Dow. Estuar Coast, and to changes in water temperature, but, at least to Shelf Sci. 15:387 364. date, these changes appear to be the result of Harlin, M.M. 1975. Epiphyte-host relationships natural variability rather than an impact of 3-unit in seagrass communities. Aquat. Bot. 1:125- , operation. 131-Hemminga, M.A., P.G. Harrison and F. Vanlent. References Cited 1991. The balance of nutrient losses in seagrass meadows. Mar. Ecol. Prog. Ser. . 71:85-96 Hillman, K., D.I. Walker, A.J. - McComb and Bulthuis, D.A. 1983. Effects of in situ light A.W.D Larkum. 1989. Productivity and - reduction on density and growth of the seagrass nutrient ava0 ability. Pages 635-685 in A.W.D Heterosastera rasmanica (Martens er Aschers.) Ecigrass 47
Larkum, A.J. McComb and S.A. Shepherd (eds). Unit Operational Studies 1986-1987. Seagrasses: A Treatise on the Biology of NUSCO. 1993. Eelgrass. Pages 33-48 in Seagrasses with Special Reference to the Monitoring the marine environment of lemg Australian Region. Elsevier, North Holland. Island Sound at Millstone Nuclear Power Hollander, M., and D.A. Wolfe. 1973. Non- Station, Waterford, Connecticut. 1992 Annual parametric statistical methods. John Wiley and Report. Sons, New York. 503 pp. Orth, R.J. 1973. Benthic infauna of eclgrass, Kemp, W.M., W.R. Boynton, R.R. Twilley, J.C. Zostera marina, beds. Chesapeake Sci.14:258 Stevenson and J.C. Means.1983. The decline 269. of submerged vascular plants in Upper Orth, R.J. 1976. The demise and recovery of Chesapeake Bay: summary of results concerning celgrass,Zostera marina,in the Chesapeake Bay, possible causes. Mar. Tech. Soc. J. 17:78-89. Virginia. Aquat. Bot. 2:141-159. Keser, M., B.R. Larson, R.L. Vadas, and W. Orth, R.J. 1977. The importance of sediment , McCarthy. 1978. Growth and ecology of stability in scagrass communities. Pages 281300 Spanina alterni/7 ora in Maine after a reduction in B.C. Coull (ed). Ecology of Marine Benthos, in thermal stress. Pages 420-433 in J.H. Thorpe Univ. South Carolina Press, Columbia, SC. and J.W. Gibbons (eds). Energy and Orth. R.J., and K.A. Moore. 1981. Submerged - Environmental stress in Aquatic Systems. DOE aquatic vegetation of the Chesapeake Bay: past, Symposium Series (CONF-771114). Nat. Tech. present and future. Trans. N. Am. Wildl. Nat. Infor. Ser., Springfield, VA. Resour. Conf. 46:271 283. Klotz, R.L. and J.L Knight. 1973. The ecology Orth. R.J., and K.A. Moore. 1983. Chesapeake of eclgrass (Zostera marina). Rpt. to Northeast Bay: An unprecedented decline in submerged Utilities Service Co.14 pp. aquatic vegetation. Science 222:51-52. Knight, J.L. and R.B. Lawton. 1974 Report on Orth, R.J., and K.A. Moore.1986. Seasonal and the possible influence of thermal addition on year-to-year variations in the growth of Zostera the growth of eclgrass (Zosrcra marina) in marina L. (eclgrass) in the lower Chesapeake Jordan Cove, Waterford, Connecticut. Rpt. to Bay. Aquat. Bot. 24:335-341. Northeast Utilitics Service Co. Osterhout. W.J.V.1917. Tolerance of fresh water Mann, K.H.1973. Seaweeds: Their productivity by marine plants and its relation to adaptations. and strateg for growth. Science 182:975-981. Bot. Gaz. 63:146-149. McRoy, C.P., and C. McMillan.1977. Production, Patriguin. D.G.1975. ' Migration
- of blowouts in ecology and physiology of seagrasses. Pages 53- seagrass beds at Barbados and Carriacou, West 81 in C.P. McRoy and C. Helfferich (eds). Indies, and its ecological and geographical Seagrass Ecosystems: A Scientific Perspective. implications. Aquatic Bot. 1:163 189.
Marcel Dekker Inc., New York. 314 pp. Phillips, R.C.1974. Transplantation of scagrasses Milne, LJ., and M.J. Milne. 1951. The eclgrass with special emphasis on' eclgrass, Zostera catastrophe. Sci. Am. 184:52 55. marina L Aquaculture 4:161-176. Neverauskas, V.P. 1985. Port Adelaide sewage Phillips, R.C. 1980. Responses of transplanted treatment works sludge outfall. Effect of and indigenous 7halassia testudmum Banks ex discharge on the adjacent marine environment. Konig and Halodu/c wrightii Aschers. to Progress report, July 1982 May 1984. EWS Rpt, sediment loading and cold stress. Contrib. Mar. 85/6. Sci. 23:79-87. NUSCO (Northeast Utilities Service Company). Rasmussen, E.1973. Systematics and ecology of 1979. Millstone Point Units 1 and 2 the Isefjord marine fauna (Denmark). Ophelia , hydrothermal survey report, July 25-August 2, 11:1-495. 1977. Submitted to Nuclear Regulatory Rasmussen, E. 1977. The wasting disease of Commission, January 1979. celgrass (Zostera marina) and its effect on NUSCO. 1988. Hydrothermal Studies. Pages environmental factors and fauna. Pages 151 in 323-355 in Monitoring the marine environment C.P. McRoy and C. Helfferich (eds). Seagrass of Long Island Sound at Millstone Nuclear Ecosystems: A Scientific Perspective. Marcel Power Station, Waterford, Connecticut. Three- Dekker Inc., New York. 314 pp. 48 Monitoring Studies,1993
1 i l 1 Roessler, M.A. 1971. Environmental change November 1971. R p t. to Millstone Point 'j ' associated with a Florida power plant. Mar. Company. . Poll. Bull. 2.87-90. Walker, D.L. and A.J. McComb. 1985 Roessler, M.A., and J.C Zieman, Jr. 1969. The. Decomposition of leaves from Amphit>olis 1 effects of thermal additions on the biota of antarctica and Posidonia australis, the major southern Biscayne Bay, Florida. Pages 136-145 scagrass species in Shark Bay, Western . in Proceed. Gulf and Caribbean Fish. Inst. Australia. Bot. Mar. 18:407-413. , Contrib. No. 1165,22nd Ann. Sess. Walker, D.I. and Wm.J. Woelkerling. 1988. A Roman, CT., and K.W. Able 1988. Production quantitative study of sediment contribution by ecology of eclgrass (Zostcra marina L) in a epiphytic coralline red algae- in seagrass. . Cape Cod salt marsh-estuarine system, meadows in Shark Bay, Western Australia. Mar. Massachusetts. Aquat. Bot. 32:353-363. Ecol. Prog.Ser. 43:71-77. Scoffin, T.P. 1970. The trapping and binding of Wood. E.J.F., W.E. Odum, and J.C Zieman.1969. - subtidal carbonate sediments by marine influence of scagrasses on the productivity of vegetation in Mimini Lagoon, Bahamas. J. coastal lagoons._ Pages 495-502 in A. Ayala Sedim. Petrol. 40:249-273. Castanares and F.B. Phleger (eds). Coastal . Sen, P.K. 1968. Estimates of regression Lagoons. Universidad Nacional Autonoma de coefficients based on the Kendall's tau. J. Am. Mexico Ciudad Universitaria, Mexico. D.F, 4 Stat. Assoc. 63:1379-1389. Zieman, J.C Jr. 1970. The effects of a thermal Setchell, W.A. 1929. Morphological and effluent stress on the scagrasses and macro-algae phenological notes on Zostcra marina L Univ. in the vicinity of Turkey Point, Biscayne Bay, Calif. Publ. Bot. 14:389-452. Florida. Ph.D. Dissertation, Univ. Miami. Coral Setchell, W.A.1935. Geographic elements of the Gables. Fla.129 pp. marine flora of the North Pacific Ocean. Am. Zieman, J.C Jr.1972. Origin of circular beds of
- Nat. 69:560 577. Thalassia (Spermatophyta: Hydrocharitaceae) in Short, F.T.1988. Ecigrass-scallop research in the Southern Biscayne Bay, Florida, and their Niantic River: Final report to the Waterford- relationship to mangrove hammocks. Bull. Mar.
East Lyme Shellfish Commission.' November 15, Sci. 22:559-574. 1988.12 pp. Zieman, J.C Jr. 1982. The ecology of the , Stauffer, R.C 1937, Changes in the invertebrate seagrasses of South Florida: A community ; community of a lagoon after disappearance of profile. U.S. Fish and Wildlife Service, the ec! grass. Ecology 18:427-431. FWS/OBS-82/25.124. 26 pp. Thayer, G.W., S.M. Adams, and M.W. LaCroix. Zieman, J.C Jr., and R.G. Wetzel. 1980. , 1975. Structural and functional aspects of a Productivity in scagrasses: Methods and rates. _. recently established Zostera marina community. Pages 87-116 in R.C Phillips and CP. McRoy Pages $18 540 in LE. Cronin (ed). Recent (eds). Handbook of Seagrass Biology: An Advances in Estuatine Research. Academic ecosystem perspective. Garland STPM Press, Press, New York. New York. NY. Thayer, G.W., W.J. Kenworthy, and M.S. Fonseca. 1984. The ecology of eclgrass meadows of the Atlantic coast: A community profile. FWS/OBS-84-02.147 pp. Tomlinson, P.B. 1974. Vegetative morphology and meristem dependence-the foundation of I productivity in scagrasses. Aquaculture 4:107 130.- , Tutin, T.G. 1942. Zostcra. J. Ecol. 30:217-226. Uphof, J.CT. 1941. Halophytes. Bot. Rev. 7:1 58. VAST, Inc.1972. Thermal survey and dye study Millstone Point, Connecticut, September-Ecigrass 49 l l
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1 4 1 Rocky Intertidal Studies Introd uction . . . . . . . . . . . . . . . . . . . . . . . . . . ... ....................... 53 Materials and M ethods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Q ualitative Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 i Abundance Measurement . . . . . . . . . . . . . . . . . . . . . . . . . ............. 53 Ascophyllum nodosum Studies ................................... 54 , Data Analysis ............ . .............. .... .. ........ 55 l Results and Discussion . . . . . . . .. .. .. . . .......... ............ 55 : Qualitative Studies . . . . . . . . . . . . . . . . . . . . ....................... 55 ; Abundance Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ........ 64 Barnacles ....... ....... .. . ..... ................ . 64-Fucus ...................... .. .. .. .... . . .... . 67 Chondms and common epiphytes . . . . . . .
... .... ... .. .. 67 Similarity Dendrograms .............. ................... 72 Ascophyllum nodosum Studies . . ........... .... ... .......... 74 ;
G rowt h . . . . . . . . . . . . . . . .... .. ............... ....... 74 Mortality .... .. .. ....... .... ........... . . . . . . . . 75 Conclusions . . . . . . .......... .. .. ......................... . . 77 - References Cited . . . . . . . . . . . . . .. ... ... .. ...... .. ..... ..... 77 . i, i i l
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Rocky Intertidal Studies ' Introduction prevailing winds and storm forces: Bay Point (BP), Fox island-Exposed (FE), Millstone Point (MP), Shore communities are particularly vulnerable to Twotree Island (~lT), White Point (WP), Seaside-anthropogenic impacts, particularly thermal effects Exposed (SE), Seaside Sheltered (SS), Giants Neck of heated effluents from coastal power plants. In (ON),and Fox Island-Sheltered (FS). The MP and the vicinity of Millstone Nuclear Power Station TT stations were added in September 1981; all (MNPS), as with much of coastal New England, a ther stations have been sampled since March substantial proportion of the shoreline is 1979. Each ' year' of qualitative sampling extends composed of rock ledge and boulders supporting a from March of that year to the following February, rich and divarse community of attached biota. i.e., the latest year of qualitative algal data (1992) Rocky shore community studies have been, and comprises collections from March 1992 to continue to be, an important aspect of biological February 1993< The 1985 sample year (3/85 - 2/86) monitoring programs associated with nuclear terminated the 2-unit operational period; the 1986 power plants along the New England coastline sample year (3/86 - 2/87) was the first of the 3-unit (Vadas et al. 1976, 1978; Wilce et al.1978; NAl operadonal period. 1993; NUSCO 1993). The FE stathm, approximately 100 m east of the Studies of plants and animals that live on rocky MNPS discharges,is directly exposed to the 3 unit
~
shores in the vicinity of MNPS continue to be part thermal plume (during part of the tidal cycle): FS, of an extensive environmental monitoring program WP, TT, and MP are between 300 and 1700 m whose primary objective is to determine whether from the discharges, and potentially impacted by differences that exist among communities at several the plume. Stations at GN, SE, and SS are sites in the Millstone Point area can be attributed unaffected by MNPS operation. to construction and operation of MNPS, in Qualitative collections were used to characterize particular since Unit 3 began operation in 1986. the attached flora at each site during each To achieve this objective, studies were designed sampling period. Algal samples were identified - and implemented to identify the attached plant and fresh or after short-term freezing. Voucher animal species found on nearby rocky shores, to specimens were made using various rnethods: in describe temporal and spatial patterns of s turated Nacl brine, as dried herbarium mounts, occurrence and abundance of these species, and to 1 as microse pc slide preparations. identify the physical and biologul factors that induce variability in local rocky intertidal Abundance Measurement communities. This research includes qualit2tive algal sampling, abundance (percentage cover) The abundance of rocky intertidal organisms was measurements of intertidal organisms, and growth expressed as percentage of substratum cover. At and mortality studies of Ascophy//um nodosum. each qualitative collection station except TT The following report discusses results of sampling (because of insufficient exposed bedrock), five and analysis in the 1993 study year, and compares permanent strip transects were established these results to those of 2 unit operational studies perpendicular to the water line. 0.5 m wide and (Mar.1979-Feb.1986), and 3-unit operational extending from '. dean High Water to Mean Low studies to date (Mar.1986 Sep.1993). Water levels. Each transect was subdivided into j 0.5 m x 0.5 m quadrats and was non-destructively Materials and Methods sampled six times per year, in odd numbered months (or a total of 46 times in the Unit 3 -! Oualitative Sampling perati n 1 peri d t d t ). These transects are considered ' undisturbed'..as they experienced no ; Qualitative algal collections were made monthly #Y# * """ Y " "' * '* "' "" * "' " at nine rocky intertidal stations (Fig.1). These qu drats m each transect depended on the slope of ; stations are, in order of most to least exposed to the transect. The percentage of substratum cover of all organisms and remaining free space in each ' - Rocky Intertidal 53
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percentage value that approximately corresponded to their actual substratum coverage. Each quadrat
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or Zone 3 (low intertidal). S v.., Ascophyllum nodosum Studies w O( - . . . , rb ,, Growth and mortality of tagged individuals of n~ coi the perennial brown alga, Ascophy//um nodosum, [\ were studied at two reference stations (GN,6.5 km west of the discharge and WP,1.5 km cast of the , discharge, Fig.1) and an experimental station (FN, ca.150 m from the quarry discharges, northeast of l)et.nl niap of the Mh"S sicinity. I O = onginal the Fox Island. Exposed sampling site,. Fig. 2). Fig 2. Ascophyllum populations at GN and WP have been **P"""'"'d"F"""'""d'""""**P"""'*"'** Ascophy#um site (1985 preseni). MP. FL. FS as in Fig 1. monitored since 1979, and those at FN since 1985. Ascophyllum was also monitored at FO, ca. 75 m clevated temperatures from the thermal plume cast of the original Millstonc quarry cut, from discharged through tv,o quarry cuts (NUSCO
~
1979-1984. The FO Ascophy//um population was 1985). climinated in the summer of 1984 by exposure to Ascophylh4m plants were measured monthly, 54 Monitoring Studies,1993
n after onset of new vesicle formation, from April to period groupings. the following April. At each statioa, each of fifty Data from Fox Island Exposed were also plants was marked at its base with a numbered analyzed separately to determine relationships plastic tag, and five apices on each plant were among qualitative algal collections and qua ntitative marked with colored cable ties. Linear growth was percent-coverage values. Similarity indices were determined by measurements made from the top of calculated between each possible pair of yearly the most recently formed vesicle to the apex of the collections at FE; these annual comparisons developing axis, or spices if branching had permitted better resolution of the community occurred. Monthly measurement of tagged plants changes that have occurred at this site. began in June; in April and May, vesicles were not A Gompertz growth curve was fitted to yet sufficiently large to be tagged, and five tips Ascophy//um length data using - non linear were measuted on each of 50 randomly chosen regression methods (Draper and Smith 1981). The plants. Tags lost to plant breakage were not Gompertz function form used (Gendron 1989) has 4 replaced, and the pattern of loss was used as a four parameters, related by the formula: measure of mortality. Loss of the entire plant was _a, . g assumed when the base tag and all tip tags were L' g g -' missing. Tip sutvival was based on the number of remaining tip tags. where L,is the predicted length at time r, a is the asymptotic length (limit of total increase for the Data Analysis growing season), k is the rate of decrease of specific growth (shape parameter), and to denotes Analysis of qualitative algal collections includes the time at which the inflection point occurs (time a calculation of a frequency of occurrence index, when length is increasing most rapidly). Growth based on the percentage of collections in which curve parameters were compared among stations each species was found out of_ all possible and between periods using 2 sample t-tests collections (e.g., at a station,in a month, during 2- (P=0.05), based on the asymptotic standard errors unit or 3 unit operation). This index was used to of the parameter estimates. Growth data calculate similarities among collections, using the representing the latest growing season (1992-1993) Bray-Curtis formula (Clifford and Stephenson were plotted for all stations together and for each 1975): station separately,with summaries of 2-unit (1979-n 2 M X 0,Xa) 1986) and 3 unit (1986-1993) operational data. S g Because the FN station was established in 1985,2-f a) 1 m (X X unit operational data from this site included only the 1985-86 growing season. where Xg is the frequency of occurrence index for species i in collection j, X, is the index in Results and Discussion collection k, and n is the number of species in common. A flexible sorting (a=-0.25), clustering Qualitative Studies algorithm was applied to the resulting similarity matrix (Lance and Williams 1967). Spatial and temporal occurrence patterns of the Quantitative analyses included determination of local benthic marine flora were - documented abundance ofintertidal organisms as percentage of through various floristic analyses, based on substratum covered by each taxon. Unoccupied monthly qualitative algal collections. This floristic substrata were classed as free space. Cover values tabulation includes all attached, macroscopic algal . of selected species were plotted against time. species. Excluded from these studied are diverse Similarities of communities among stations and diatom taxa, blue-green algae and some crustose, between operational periods were calculated using endophytic or endozooic species. These elements the Bray Curtis coefficient formula cited above, of the microbiota are present but too difficult to substituting untransformed percentages for consistently collect, and, for many species, to frequency of occurrence indices. The same identify. Also included were taxa that are, or may clustering algorithm was used to form station! be, conspecific or subspecific forms, or alternate Rocky Intertidal 55 1
life history stages of erect macroalgae. For major groupings, relative to recent previous years , simplicity, we refer to each of these entities as a (e.g., NUSCO 1992, 1993). Excluding the FE 3-species throughout this report. Except where unit collection, primary groupings of all other roted, nomenclature follows that of South and collections are distinguished by floras which Tittley (1986). . develop on differing substrata. Collection areas at A summary of results from qualitative sampling sites comprising Group I are composed of bedrock studies conducted since 1979 is presented as ledge, with subgroups separated into exposed sites , percent frequency of species occurrence during 3- (WP, MP, BP and FE 2-unit; Subgroup la) and unit and unit operational studies by month sheltered sites - (GN and FS; Subgroup lb). , (Tab!c 1) and by station (Table 2). A total of 126 Collection substrata at Group 11 sites (TT, SS and taxa were collected and identified during 1992, SE) are primarily large boulders and relatively which was within the range of annual totals for 2 unstable cobble with few horizontal surfaces. The unit (101 -131) and 3-unit (118-126) years (NUSCO strong dissimilarity of the FE 3-unit collection 1993). Three species, new to our studies, were (Group'III) to all other collections is due.to the collected during 1992; Phyllophora traillii was unique floristic assemblage shat has developed at ' collected once at FS, Eudesme rirescens once at this site in response to exposure to the 3-unit WP, and Grifpthsia globulifera was collected four thermal plume. times, twice at both WP and SS. These additional A similar analysis was applied to annual three species bring the overall total of species collections at FE (Fig. 3b) to illustrate yearly collected since 1979 to 161. changes to the algal community brought about by-These floristic analyses have been successful in important power plant operational events. Group documenting occurrence and distributional trends I represents collections made during 2-unit 1-cut of attached algal species throughout the Millstone operation, when the unimpacted flora at FE was , area. Manyof these floristicdifferences, identified similar to that observed at other exposed sites (see over time (among seasons or years, or between Fig. 3a and NUSCO 1987). Temperature operational periods) and among stations, provide conditions ,were altered substantially due to I information on natural factors which produce operational changes occurring in 1984 (2-unit,2 variability in the local flora and establish a baseline cut operation) and 1986 (Unit 3 start up), and this from which power plant impacts can be assessed. situation was reflected in the characteristic For example, seasonal floristic groupings or suites disturbed or early successional st:;ge flora collected of species characteristic of warm water collections at FE from 1984 to 1987 (Group 11). Elevated , (e.g., Champia pamda, Lomeraaria baileyana, temperature conditions persistrd, but.were more Ceramium diaphanum, Dasya baillouriana, consistent in subsequent years comprising Polysiphonia novae-angliae, Giffordia mitchcl/iae, collections in Group 111. These conditions allowed and Enteromorpha clathrata) and cold-water for more long-term deulopraent of the unique collections (e.g., Dumontia contorta, Popsiphonia flora now observed at FE, characterized by the urceolata, Spongonema tomemosum, Desmarestia presence of warm water-tolerant species not typical viridis, Spongomorpha arcia, Afonostromapulchrum of other sites (Agardhiella subulata, Gracilaria and Af. grevillei) noted in 1992, were consistent rikvahine and Sargassum flipendula), absence of with those identified over the entire study period common cold water species (Afastocarpus stellatus, and discussed in detail in previous reports Dumontia comorta and Polysiphonia lanosa) and (NUSCO 1992, 1993). Similarly, consistent extended or reduced periods of occurrence of the occurrence of species which have historically seasonal species mentioned previously with warm exhibited site specificity (e.g., Prasiola stipitata and water and cold water affinities, respectively.
- Gelidium pusillum) was also observed during 1992. Similar floristic shifts have been observed by other Relationships among composite collections made researchers studying attached algae near thermal-during 2-unit and-3-unit periods at each station effluents (Vadas et al.1976; Wilce et al.1978; were examined using cluster analysis' techniques Schneider 1981).
and illustrated by the resulting clustering dendrogram (Figure 3a), in short, the addition of 1 1992 data has resulted in no substantive change in 56 Monitoring Studies,1993 i
9 TAllLE1 Quahtahve algal collechons (Mar.1979 Feb 1993) by motuh, dunng 2' unit (3n9-256) and 3 umt (ho 2/93) opeistmg pern>Js Values reproent humber of hmes found, as a percentage of pmoble Omn found Tau enchwed in quotes are,or may tr.conspecific or 6ubstrofic e formt or ahernate I fe history stagn (see teu for addmonal esplanrhon), a dash leforc a species end. rain that n u mduJed in milechons made in the latest regort yeer. 2-l)mt Operation 3 lino Operation itin.fophyta laj [c jh M & LiLq lui aug 5,g pch Dcg En b ? h M M Ja i g uf, hey g g N wlice stylonema alsidu 5 2 2 2 0 4 9 12 21 33 7 5 3 $ 2 2 0 2 2 8 10 10 3 5. Erythrotrichopelta cilians 32 18 18 12 to 11 11 18 32 49 32 25 24 21 13 17 13 6' 8 19 29 46 25 29 Erythrotnchia carnea 4 4 0 0 2 2 0 0 9 4 4 2 2 $ 3 11 2 0 5 3 14 14 6 8 Erythmdadia subintegra 0 0 2 0 0 2 0 ? 2 5 5 5 2 0 0 2 0 0 0 3 2 3.3 0 Erythrolchia dacigera 7 4 2 0 4 0 2 2 7 5 5 5 2 3 5 2 2 0 2 0 5 10 8 5 i
!!angia atropurpurea 65 79 77 86 26 11 4 7 IH 21 35 54 60 73 95 75 38 17 6 6 30.27 35 44 Porphyra leuamticta 46 M 61 65 44 20 12 9 9 19 18 25 68 78 86 64 75 32 11 6 6 30 32 43 Porphyra umbihcaha 46 53 77 77 93 72 58 40 25 14 23 2M $9 57 76 90 83 59 43 37 29 3M 43 59 Porphyra hneans 0 0 0 0 0 0 0 0 0 0 0 2 2 2 3 0 0 0 0 0 0 0 0 3 Porphyropsis coccinen 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0'0 o o Audounclla purpurea 4 4 0 4 2 2 2 4 2 0 $ 2 0 0 0 0 2 0- 0 0 0 0 0 0 Audoumella secundata 35 53 37 35 35 40 25 23 21 37 18 19 30 30 25 35 25 17 10 11 10 13 8 3
-Audouinclla dannii 9 0- 2 7 4 4 5 2 2 2 7 0 0 0 3 2 3 0 5 3 0 $ 2 0
-Audouincue sanana 10 $ 14 12 9 11 5 5 19 18 7 11 6 5 8 24 16 3 3 5- 17 16 I r. M Audouinella sp. 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 Audouinella d,nyac 0 0 0 0 0 2 0 2 0 0 0 0 0 0 0 0 0 0 0 30 0 0 2 Gelidium pusilium 7 9 4 9 i 9 11 9 9 14 12 12 25 22 21 19 19 16 21 22 22 25 34 32 Semation helminthoides 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 11 3 0 0 0 0
,llonnemaisonia hamifera 9 9 18 18 26 Si 33 9 0 0 5 5 2 6 6 13 25 33 37 10 3 2 0 5 Trailliella intricata' O O 2 0 0 4 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0
-Agardhiella subulata 5 5 5 4 11 14 12 12 18 11 12 12 13 13 to 5 3 to 11 11 14 13 16 to Polyido rotundus 5 11 0 7 11 4 !! 12 14 14 19 12 5 3 3 2 3 n n 8 3 0 3 5
-Cyntrwloniurn purpurcum N1 77 68 74 79 79 4u 23 12 47 56 6H 68 6N $7 $6 M 65 29 . I l 14 19 43 48 Gracilaria tavahiae 0 0 0 0 0 0 0 2 2 0 0 0 10 6 3 3 2 0 0 3 5 3 6 M
-Ahnfelun phcata 47 51 49 49 42 44 37 37 37 an 47 Sn 22 22 17 14 19 22 21 13 la 13 la 22 Phyllophora pseudoccianoides 23 14 16 16 11 11 12 12 4 19 16 in 8 11 2 3 o N 3 1 5 N 4 10
+Phyllophora tradhi 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2.0 '
Phyllophora truncata 12 18 7 5 V 12 12 9 18 il 16 19 5 6 14 6 6 l0 4 3 2 2 5 3 6
-Chondrus crispus 96 96 W 98 W 98 98 98 9o 94 un 94 98 94 97 97 97. 97 98 98 98 97 W 98 i Mantocarpus stellaius 74 Sh $3 47 $6 58 60 56 58 b5 77 h$ 67 70 65 M 65 70 63 07 (A 60 bM 08 Petmecht tniddendortu O O O O O O O O O O O 2 0 0 0 0 0 0. 2 0 0 0 0 0 I4htstophysema georgir 0 2 7 2 9 2 2 4 4 0 0 0 0 0 3 0 6 3 0 0 0 0 0 0 +
4hrallma offirmahs 60 61 58 So 51 51 61 63 60 68 58 07 71 76 57 62 ' 63 68 59 67 00 62 62 76 Dumontia contoria 46 65 81 62 81 47 5 2 2 0 2 7 33 49 65 76 75 32 10 2 0.0 0 6 }
-Oloniphonia capinaris 2 0 2 0 0 0 0 0 6 0 0 0 0 0 0 0 3 20 0 0 0 0 0 l
-Chorcocolax polysiphomac 9 12 12 9 9 2 4 4 2 5 0 9 14 11 8 10 .. 6 5' b 3 n 10 5 o >
Ilildenbrandia INbra 4 2 2 2 0 0 2 0 2 5 0 2 2 0 0 0 0 5 2 0 3 0 2 Palmana palmata 32 33 49 44 39 46 33 28 21 12 28 30 19 27 22 19 22 19 29 21 14 14 10 19 Champia parvula 35 21 11 7 4 4 35 65 74 79 65 4h 14 e a 5 3 8 .49 76 79 67 49 38 slementans luileyana 4 0 0 0 0 0 5 10 49 29 7 2 0 0 0 0 0 2 n 19.2J I4 3 0
-loroentaria dAellosa 11 5 9 In 7 2 2 4 7 4 7 4 5 5 M N 6 0 2 2 0 0 2 2 ,
tomentana orudensis 2 2 4 0 0 0 0 0 2 5 0 0 2 2 0 0 0 0 0 0 2 0 0 2 Anathamnion cruelatum 47 25 5 IN 7 16 46 63 70 74 74 67 24 in - 10 ll 17 22- 41 $2 29 ' 3% 30'lh ,
-AnthhamnKm nipponicum 0 0 0 0 0 0 0 0 0 0 0 0 73 71-43 25 35 40 51 63 75: 70 79 81 Calkthamn on corymbohum 0 0 0 0- 0 2 0 1 9 5 5 0 0 o 0 .0 0 0 3 0 0 0 -. O J0 0 Calkthamnion rmeum 7 2 2 0 0 0 9 1R 35 1M 14 5 0 0 3 2' 3 5 6 17 22 . 8 ' 8 5
-Caththamnion tetragonum 65 46 23 33 21 11 25 26 44 46 72 53 to 17 14 17 10 3- 5 8 to 13 to 13 [
Calkthamnion tysoides 0 0 0 0 0 0 4 4 2 0 0- 0 0 0' O o 0 'O.2 0 ,O. 0 0 0 t
/Caththampion baHeyp 0 0 0 0 0 0 0 0 0 ~ $ 7 2 43 29 21 13 8 11 27 25 32 .38 52 38 Ceramium desiongchampa 4 4 0.2 0 2 0 4 4 4 4 9 3 2 0 2 3 0- 0 0 2 . 3' 3. 2
-Cera%um diaphanum 7 0 0 2 0 0 25 M 49. 51 11 12 - 0 0 0 0 2 5 30 57 52 33 14 ~.2 -[
-Ceramium rubrum 88 88 74 81 89 91 95 84 95 93 91 M 89 92 75 79 81 R9 90 90 89 86 87 87 Ceramium fastigiatum 0 0 0 0 0 .0 0 0 2 0 0 0 0 0 0' O O O O-0 0 0 0 0
.Spermothamnion repens $4 33 28 26 18' 28 28 35.40 72 74 70 43 29 27 17 24 41 30 4R .32 4l l 40 49
$ppsdia (damenhwa 0 0 0 0 0 2 2 4 . 12 4 2 2 0 0 2 0 0 0 0 3 n 10 'n 3
-Scageha pylanaci 5 2 2 4 5 0 0 2 2 4 4 4 0 o 5 1 1 2 2 3 0 0 0 2 ,
-Onffdhaia globuhlera 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 2 2 0 t
Rocky Inicflidal 57 1 l a . .s. p ..,y gg n y ,r--v.w->.-,,-w ,y.wm 4 7 , ,, ,e, --,n.- , - ,m,e . + , , e- +- m
' TABLE 1. (cont.)
' 2-Unit Operation 3 Umi Operanon Ithodophyta Jyr! M pjpr g May Jun M &g M Osth Ecs Jan Fetgr &May Jun Jule,ug M Oct, Nov!ke '
-Onnnelha mmericanum 4 0 0 2 2 0- 4 9 2 11 12 7 5 0 2 0 0 3 8 n 13 11 to 6
-Phycodrys rubens 2 4 5 12 7 7 4 5 5 7 7 0 0 0 2 4 6 8 3 2 2 -3 2 5
-Dasya baillouviana 7 2- 0 0 0.0 7 39 30 25 23 11 6 2 0 2 0 2 13 35_ 27 38 30 27
-Chondria sedifolia 0 0 0 0 0. 0 0 4 5 5 0- 0 0 0 0 0 0 0 0 2 5 2 0 0
-Chondria buleyana 2 0 2 0 2 0 0 4 16 11 0 5 2 0 0 0 .0 0 3 $ .11 6 3 2 ,
-Chondria tenuissima 0 0 0 2 0 0 4 2 4 0 0 0- 0 0 0- 0 0 0 3 ~5 2 2 0 0 Chondna dasyphylla 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 'O O o-0
-Polysiphonia denudata 0 0 0 0 0 0 5 0 4 9 5 7- 2 2. 2 0 5 3 2 3 0 2. 0 3
-Polysiphonu harveyi - 70 39 25 23 19 53 82 95 91 65 68 63 - 17 8 6 8 11 27 35 '40 38 21 29 17
-Polysiphonia lanosa 82 74 68 60 70 63 61 60 65 72 65 74 73 70 70 65 71 76 70 65 68 67 75-76 Polysiphonia nigra 5 9 7 11 18 to 2 4 2 4 4 7 2 .5 to 8' 17. 13 0 0 0.3 2 3
-Polysiphonia nigrescens 19 . 14 18 32 19 28 23 16 18 25 23 21 13 22 5 13 16 '19 16 16 16 11 11 17 ,
-Polysiphonia urceolata 19 16 30.54 60 32 18 4 4 2 2 4 14 21 19 24 32 22 5 5 3 2 2 11 1 Polysiphonia clongata 0 0 0 0 0 2 0 2 0 0 0 4 2 0 0 0 0 '2 0 0- 0 0' 0 0 Polysiphonia fibnikna 5 2 0 0 0 0 2 0 0 2 0 12 3 0 0 0 o' 0 0 0 2 2 03 3- 0 8 ~ 3 5 Polysiphonia ficxicauhs 0 0 0 0 0 0 t' O O O O 2 13 2 0 0 0 0 0 Polysiphonia novac-angbac 70 61 42 30 39 41 68 74 74 88 84 84 94 87 Sh 40 40 7o 90 97 98 97 vs 9x Rhodomela conferwades 7 9 30 19 4 4 0 2 2 0 2 2 2 3 '1 6 3 0 0 ~ 0 0 0 0 0.
2-Umi Operanon . 3 Unit Operanon Phaconhvta Jan Feb Mar ghjn M1 M3,u M Oct Nov Rei Jan l'eb Mar &Mn Jun Jul3ug SED 2d No@CC
-Ectocarpus fasciculatus 7 18 12 26 33 35 25 16 28 32 19 9 0 3- 16 21 30 32 17 14 22 19 25 11 '
Ectocarpus siheulosis 19 32 47 53 60 70 60 39 28 26 23 la 16 32 J0 51 44 46 32 30 22 17 29 19 Ectocarpus sp. 5 12 9 7 0 5 7 4 7 2 5 4 2 0 3 2 0 2 2 2 0 0 0 2 Giffordia granukna 5 2 4 4 4 7 2 0 5 2 5 4 2 3 2 5 8 13 3 0 2. 0 8 3
' Giffordia mitchelhae 4 7 2 5 14 19 19 32 32 28 14 7 10 8 5 3 14 13 13 32. 43 43 22 11
-Pilaycita htiorahs 21 18 25 35 51 32 12 16 14 21 12 18 'll 16 22 27 38 38 6 II 3 19 8 16
Spongonema tomentosum 18 28 42 30 19 0 2 4 0 7 2 2 3 22 43 25 14 3 2 3 0 6 0 5
- Entonema accidioides 0 0 0 4 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
-Acinciospora sp. 0 0 0 4 2 0 0 2 0 0 0 0 0 0 0 0 0 2 0 0 00 0 0' -i Feldmannia sp. 0 0 0 0 0 0 0 0 0 2 2 0 0 0- 0 0 0 0 0 0 0 0 0 0- >
Ralfsia verrucosa 42 56 37 39 46 47 58 65 6S 67 54 44 b5 65 52 59 43 44 67 78 79 c3: 70 c5 Elachista fucicola 42 51 61 72 86 82 70 81 77 49 35 26 54 59 67 79 75 87 87 ' 81 73 60 59 52
-ilalot hra lumbncahs 0 2 0 0 5 4 2 0 2 2 0 0 0 0 3 3 n 2 2 0 0 u. 0 0 trathesta dtfformis 0 2 0 9 19 20 26 11 0 0 0 0 0 0 0 16 35 46 37 5 0 0 0 0 'i Chordana flagelliformis. 0 0 0 5 19 49 37 30 19 5 2 4 0 0 2 2 11 . 19 '22 13 6 3 0 0' i
-5phaerotrichia dwancata 0 0 0 2 5 11 2 0 0 0 0 0 0 0 2 0 3 0 0 0 0 0 0 0 Cladosiphon taterac 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Eudesme virescens 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0. 0'0-0
-Pogotnchum fikforme 0 14 5 2 5 0 0 0 2 0 0 0 0 3 3 3 0 0 0 0 0 0 0 0
-Desmotrichum undulatum O 2 14 7 4 2 0 0 0 4 0 4 0 H 6 6 6 5 2 0 'O O O O I
-Phacosamon colknsii 0 4 2 0 0 0 0 0 0 0 0 0 0 2 5 0 0 0 0 0 0 0 0 0
-Punctana laufolia 2 9 16 12 4 9 0 0 0 5 4 4 3 5 8 3 8 o 2 0 0-0 3'6 Punctana plantaginea 2 4 4 2 5 7 7 5 4 0 2 0 0- 3 0 2 6 3 3 2 2 2 3 3
-Petalonia fascia 70 84 68 80 84 84 72 9 5 12 42 63 70 90 84 97 92 81 51 8 2 6 38 54 -
-$cytosiphon lamentana 46 79 93 95 93 95 86 18 5 9 21 32 27 70 90 98 94 90 65 8 0 2 o 17 Delamarca attenuata 0 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 'O O O O.O !
-Desmaresua aculcata 7 2 9 16 9 12 2 7 4 7 11 4 8 8 5- 8 13 8 19 3 5 8 6 5- l
-Desmarestia vindis 2 4 30 44 49 39 2 0 0 0 2 0 0 5 24 48 54 35 0 2 0 0 0 0
-Chorda fitum 0 0 0 2 9 19 to 0 0 0 0 0 0 0. 0 2 8 25 17' 5 0 0 0 0: )
Chorda tomentosa 0 0 5 18 28 2 9 0 0 0 0 0 0 5 to 29 21 e 0' o 0 .O' o 0. _i laminana digitata 2 0 0 0 '4 0 0 2 0 0 0 4 0 2 25 -o 0 0 0 2 20-0 l
-Laminana longieruns 9 12 9 14 14 11 12 11 12 18 12 7 11 13 11 14 17 16. 17 '25 17 '22 16'13 (j
-Laminana saccharina 53 37 53 63 82 77 82 75 60 58 49 58 51 38 57 68 67 97 78 75 62 63 59.54 30 16 - 9 12 .16 16 19 21 21 32 37 39 33 27 22 17 27- 22 24 19 30 ,37 ' 37 41 Sphacclaria cirrosa
-5phacclaria rigidula 0 0- 0 0 0'0- O. O' 2 0 0 0 0 2 0 0 2- 0.'O '2 0 -2: 3'O 4
-Ascophyllum nodasum 96 96 98 98 98 98 98 98 96 96 96 96 95 95 95 95 95 95 - 95 95 95 95 95 95 :l Fucus datichus s edentatus 7 11 18 21 16 4 2 2 0 2 3 4 6 '8 13 13 3 3 0' 5 ' 6 ' f2 0 3
' ')
-Fucus datichus s evanescens 14 12 21 19 23 7 2' 5. 0 4 9 0 2 8 13 13 . 3 2 5 5.2 3 2 - 2 i l -Fucus spirain 2 2 2 9 5 11 7 7 14 7 7 4 10 -5 6 11 10 14 11 to 16 ' 13 6 10 Fucus vesiculosus 90 % 98 98 98 100 100 100 96 96 96 94 100 100 100 100 l00 100 100 100 100 100 100 100 a
,{- -Sargassum fikpendula 0 0 0 0 0 0 0 2 0 0 0 0 M M n n 6 n 6 8 8 8' N.M ! . 58 Monilofing Studies,1993 4. e
. ~ ,_ . - _ _ - . _ _-- . - , , ,
;I
. TABLE 1. (cont.)
2-Umi Operation 3 Umt Opration Chinrophyt a _ lag M g g g g gig g O g M y J M h gr g Jy lui g gpf)g Novt)ec
. Ulothru flacca 53 61 74 70 47 7 5 0 2 9 23 32 51 70 70 70 29 8 6 2 5 8 16 30
-Urospora penicilbformis 61 72 74 70 30 7 2 4 2 7 28 44 60 57 02 46 25 8 10 8 14 16- 30 48 Umspora wormsLJ oldii 9 .7. 9 16 2 7 4 0 0 0 0 2 8 6 17 6 Il 5 h o 5 to ~ $ 16
'Urospora collabens' 7 19 9 2 5 2 2 0- 0 0 0 4 2 2 2 0 3 0 2 0 0 0 0 0 Acrochaete viridis 2 2 02 0.0 0 0 0 2 2 2 0 0 0 0. 2 2 2 0 0 0 0 0 ,
-Monostroma grevillei 25 58 54 60 $1 12 2 2 2 0 7 5 3 51 54 73 46 2. 0 0 'O O O3 ,
.Moncatroma pulchrum 19 44 88 91 86 16 4 0 0 4 2 2 0 24 76 79 71 5 0 0 0 0 0 0
-Monastroma nrysperma 2 0 0 -2 2 0 0 0 0 0 0 0 0 2 3 6 6 2 0'O O O O O Spcmgomorpha arcta 7 18 39 51 54 32 5 0 0 0 4 4 5 17 24 30 46 22 5 0 0 0 0 2
-Spongomorpha aeruginosa 4 2 7 14 18 16 5 4 4 0 0 0 2 0 2 21 33 25 3 0 0 2 0 0
'Codsolum gregarium' O O O O O O 2 0 0 0 0 0 0 0 0 0 .0 0 0 0 0. O UO r Capsosiphon fuhescens 0 2 0 5 4 4 2 0 4 0 0 0 0 0 0 0 0 0-0 0 0 0.0 0 l Capsosiphon groenlandicum 2 12 12 14 11 7 2 0 0 0 2 11 3; 2 2 2 2 2 0 0 2 0-0 2
-Blidmgia minima 58 44 44 53 70 65 47 67- 38 49 47 53 65 78/65 75 79 81 73 81 78 62 71 67 Illidingia marginata 9 4 0 0- 2 0 4 0 04 2 2 0 0 0 0 2 2 3 0. 0- 0 0O c Enteromorpha clathrata 4 5 2 12 18 19 37- 46 37 28 5-4 3 0 3 5 8 10 25 37 41 16 32
-Enteromorpha flexuosa 33 33 25 28 37 40 40 32 46 60 53 35 52 51 59 40 St. 38 44 51 70 56 63 60
-Enteromorpha intestinahs 25 26 35 44 49 47 46 51 35 25 21 16 17 17 25 40 32 37 46 35L.30 29 11 14 Enteromorpha ILua 51 30 32 56 67 63 65 60 60 70 63 49 48 49 54 76 76 76 70 68 76 73 65 56-Enteromorpha prohfera 42 39 33 28 35 37 25 33 32 47 44 47 14 14 6 16 16 21 10 14 10 22 17 24 Enteromorpha torta 2 0 0 0 4 7 5 7 2 5 2 0 0 0 0 0 2 5.3-0 0 0' O O
-Enteromorpha ralfsii 0 0 0 0 0 11 7 4 5 2 2 0 0 2 2 0 2 5 6' 6 33 0 0-Percururia percursa 2 0 0 5 4 9 4 2 2 2 0 0 0 0 2 0 0 0 0 0 2 2- 0 0 Ulva lactuca % $8 77 84 89 98 93 91 90 98 94 '96 94 94 in 83 H9 97 97 98 100 95' 95 94 ,
-Praslota stipitata 19 21 23 23 23 23 28 25 25 25 19 30 37 35 24 27 . 30 32 35 29 32 27- 29 32
-Chaetomorpha knum 79 58 40 37 56 89 91 95 96 95 84 74- 56 33 19 21 48 70 90 90 86 81 70 54 Chaetomorpha melagonium 0 2 0 0 0 'O O O O O O O O O O O 2 0 0 0 0 0. 0 0
-Chaetomorpha aerea 30 25 20 21 19 2n 37 28 42 30 37 30 44 46 27 JI 46 40 51 51 38 48 46 44
-Cladophora albida 0 0 2 2 11 9 16 11 12 4 4 2 0 0 0 3 0 3: D 5' 5 2 0-0 .
+ Cladophora Dexucsa' 14 2 4 7 14 25 37 26 18 28 12 11 5 2 2 5 24 59 78 40 44 33 14 8
'Cladophora glaucescens' O -0 0 0 2 2 2 2 0 u o 0 0 0 0 2 0 0 0 2 2 0 o'O C!adophora lacioirens 0 0 0 2 2 4 4 0 4 2 0 0 # u o0 0 0 2 0 0 0-0 0
- Cladophora refracta' 9 7 2 2 5 32 33 26 28 37 18 le 3 5 5 2 5 11 3 3 2 3 2 6
-Cladophora sericea 12 5 5 25 53 42 35 37 23 21 18 14 11 2 14 24 35 27 35 35 24 22 14 22 ,
'Cladophora crystalhna' O O O O O 22 0 0 0 0 0 0 0 0 0 0 0 0 5 3 0 0 0
-Cladophorn hutchinsiae 2 4 4 2 9 9 7 12 12 14 11 2 3 3 2-3 5 11 10 6 6 5 $~ 2-Cladophors rupestris 0 2 0 2 5 2 9 1 0 2- 2 0 2.2 2 0 10 10 6 .5 3 2 3f0 ,
-Cladophora ruchingeri 0 0 0 0 0 o o 2 0 0 0 0 0 0 2 0 $ 6 14 22 11-- 13 10 0 <
-Rhaoclonium ripanum 9 30 25 to 18 18 ' 30 30 28 23 12 16 8 0 10 5 8 25 24 27 -13 14 3 8
. Rhizoclonium kerneri' 2 0 4 0 0 4 0 0 0 01 0 2 0 0 2-0 2 2 3- 2 0 0 0 0-
'Rhuoclomum tortuonum' O O O O O 5 0 0 0 0 2- 0 0 0 0- 0 o 0 0 0- O. 0 -0 0 Bryopis plumosa 7 0' O O 4 2 12 to 11 12 7 7 o 3 0 0 u 2 13 6 11 3 6 -Bryopm hypnoides 0 0 0 0 2 5 9 2 5 7 2 4 2 0 2 0 6 13 22 17 3 8 10 5-Derbesia manna 7 5 4 9 0 0 2 4 4 9 12 11 0 0 0 0 2 0 2 2 2 5 0 ' 2. !
..Codium fragoe 89 79 68 75 75 82 81 84 88 95 89 86 94 92 73 75 Hi 89 95 97 9s 90 89 90
.i 1
i l
.i i
u i Rocky intertidal: 59' l j q
I TAHLE 2. - Quahtative algal collections (Mar.1979-Feb.1993) by station. during 2.ums (3/79 2>86) and 3.umi (3sh-2N3) operatmg periods. Taxa eneksed in quoies are, or may be, conspecir e or subspecific torms. or alternate bre history wages. see text for addiuonal czplanation. Values represent number of umes found, as a perecntage of poss%Ie times found. De last three columns represent 2-umt 3-urut, and overall study summanes (T= present. < 1%) 2 Umt Operation 3-Unit Operation Summanes Rhodonhyta ' M N E H E DS M SE SS ON llP g H [Jfi D WP $1 % 111 lif M Stylonema alsidii 14 11 6 2 12 11 10 1 6 13 4 0 1 10 2 7 0 0 8 4 h Erythrotrichopchis cilians 32 20 19 23 26 20 27 11 23 40 14 8 12 46 19 29 4 14 23 21 22 Erythrotnchia carnea 4 2-0 2 1 4 4 4 0 12 1 6 1 17 10 - 5 1 2 2 6 4 Erythrocladia subintegra 1 4 4 2 4 0 0 1 2 0 0 2 0 8 0 0 0 0 2 1 2 Erythropeltis discigera 4 6 6 0 $ 2 1 2 5 0 7 2 2 10 0 2 4 4 4 3 3 Bangia atropurpurea 48 45 54 35 42 30 49 38 25 50 50 46 40 42 32 48 43 30 40 42 41 Porphyra leucosticta 42 27 56 44 32 23 37 31 24 50 43 62 46 51 49 40 42 30 33 46 40 , Porphyra umbilicalis 64 42 50 54 54 42 52 64 33 42 50 73 50 76 49 54 74 37 50 56 53 Forphyra lineans 0 0 0 0 0 0 1 0 0 0 0 2 1 0 0 1 2 0 T l T Porphytopds coccinea 0 0 0 0 0 2 0 0 0 0 0 1 0 0 1 0 0 0 T T T Audoumella purpurea 2 0 0 0 14 0 1 0 1 0 0 1 0 0 0 0 0 0 2. ' T I Audoumella secundata 39 49 44 23 24 24 30 27 25 24 32 27 8 -15 10 10 24 18 31 19 25 Audouinella davieui 5 4 2 6 2 2 4 4 4 2 2 1 0 2 1 2 2 2 4 2 3 Audouir.cIla saviana 17 12 19 15 12 13 8 2 6 17 8 5 7 18 13 14 2 10 11 11 11 Audouinella sp. I 1 0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0 T T T Audouinella dasyac 0 2 0 0 0 0 0 0 0 0 0 0 0 0 2 1 0 0 T ~1 T Gelidium pusilium 7 0 0 4 1 63 1 0 0 71 0 1 0 24 100 10 1 1 9 23 17 Nemation helminthoides 0 0 0 0 0 0 0 0 0 0 7 4 2 0 0 0 0 0 0 1 1 Bonnemaisonia hamifera 1 20 2 33 0 1 20 29 33 1 2 2 33 0 1 14 21 37 15 13 14
*Trailliella intricata' O O O O O O O O 1 0 0 0 0 0 0 0 0 1 1 T T Agardhic!!a subulata 5 7 8 2 24 8 17 4 12 0 2 1 0 60 0 6 1 4 10 11 11 Polyides rotundus 4 8 8 8 5 8 18 2 26 1 0 5 8 o 0 5 1 10 10 4 7 Cyuoclomum purpurcum 58 50 67 65 58 58 71 49 62 61 24 52 68 7 32 54 52 57 59 45 52 '
Gractlana tikvahiae 0 1 0 0 1 0 0 0 0 0 0 1 0 33 1 1 0 0 'l 4 2 Ahnfehia phcata 20 39 58 92 73 19 52 24 55 8 7 31 42 1 6 33 14 18 45 18 31 Phyllophora pseudoceranoides 3 7 10 29 10 8 40 7 11 5 1 5 11 2 l 17 4 to 14 0 to Phyllophora traillii 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 I Phyliophora truncata 11 11 13 10 11 11 21 5 13 4 2 2 18 I i 12 4 5 12 5 8 Chondrus crispus 100 100 100 100 79 100 100 100 100 100 100 100 100 80 100 100 100 100 97 98 ~ 98 Mastocarpus ucilatus 25 61 90 100 17 21 65 90 98 29 43 95 100 0 43 100 95 95 60 67 64 - Petrocelis middendorDi 0 0 0 0 0 0 o 0 1 0 0 0 0 0 0 0 0 1 T 1 T Rhodophysema georgii 0 1 0 0 0 2 4 1 12 0 1 0 1 0 1 0 1 5 2 1 2 Coralbna officinals 2 100 100 31 95 70 82 32 27 1 98 99 31 94 100 94 54 18 60 65 63 Dumontia contorta 39 19 40 48 20 45 33 32 39 39 10 31 50 0 42 25 19 45 35 29 32 Gloisiphorus capillaris 0 0 2 0 1 0 0 0 0 0 0 0 0 1 0 2 0 0 T T T Chorcocolax polysiphoniae 14 21 4 2 2 0 5 0 o 11 2n 14 4 0 0 2 0 12 o 8 7 lhldenbrandia rubra 1 0 0 15 0 1 1 O 1 0 0 0 8 0 0 1 0 1 2 I I Palmana palmata 36 39 17 69 8 s 44 25 58 15 12 o 58 2 2 23 15 42 33 20 2o Champia parvula 37 35 15 33 31 38 c1 20 4o 30 25 27 3a 42 35 42 2o 40 37 34 35 Lomentana baileyana 21 7 2 6 17 13 17 2 2 11 0 0 0 12 la 10 1 4 10 4 8 Lomentana clavellosa 5 5 0 10 2 5 10 7 12 1 0 5 4 0 0 to 1 8 6 3 5 lamentana orcadensis 1 0 0 8 0 0 2 0 1 0 0 ~0 1 0 0 2 0 1 1 1 1 Antilhamnion cruciatum 44 52 33 40 33 40 62 30 43 19 27 29 27 25 23 33 18 :o 43 25 33 l Aritithamnion nipponicum 0 0 0 0 0 0 0 0 0 38 69 85 65 68 52 61 46 45 0 59 31 Calkthamruon corymtu.um 0 7 0 2 2 1 5 1 '1 0 0 0 0 0 0 0 0 0 2 0 1 Calhthammon roseum . 10 6 10 4 18 11 10 4 8 4 2 4 7 29 5 h 1 2 9 7' 8
' Calhthamnion tetragonum 38 37 52 63 50 25 45 23 31 2 21 20 18 1 8 17 0 10 39 11' 24 -j Calbthamnion byssoides 1 5 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 T T .I
'Caththamnion haileyi' 2 2 2 2 0 0 1 0 1 25 49 45 39 1 21 37 18 17 1 28 15 l Ceramium destongchampii 13 1 0 4 0 4 1 1 0 2 4 1 1 0 0 2 2- 1 -3 2. 2 I Ceramium diaphanum 18 29 2 33 8 13 26 19 19 8 20 5 20 4 5 29 24 24 19 in 17 Ceramium rubrum 88 95 88 92 87 77 94 87 66 85 99 76 89 7o 87 vo 83 85. 88 8n 87 Ceramium fastigiatum 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 U T ;
5permothamnion repens 46 58 40 46 21 27 68 2r. 48 44 44 19 27 II 25 co k 45 T ~ 34 V 42 'j Spvndia filamentosa 12 1 0 0 0 4 1 0 0 15 2 I i o 1 I O O 2 3 2 Scageha pylaisaci 1 4 6 2 0 1 6 1 4 0 2 0 1 1 1 1 5 2 3 2 2 i Gnffithna globulifera 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 2 0 i T ! 60 Monitoring Studies,1993 l
, , ,--. - - - , a-- 4
F TABLE 2. (cont.) 2-Unit Operanon 3-Umt Operanon Summanes Rhodorihyta M J1P tiP H g [S M $JG M GN itP MP 1T Q D E g Ss 21) 311 101 Ortnnellia amencanum i 1 2 2 1 1 13 2 12 0 0 'O 4 23 2 10 2 12 4 6 5
- Phycodrys rubens 0 0 2 8 1 2 18 6 11 0 1 0 10 0 0 ,10 1 7 5 3 4 +
Dasya baillouviana 8 14 2 10 11 21 18 4 13 19 13 10 6 45 13 21 2 6 12 15 14
- Chondria sedifolia 5 1 0 2. 0 1 0 0 1 4 0 0 0 0 2 0 0 0 .i. I 1 g 3 3 3 Chondria baileyana .5 5 13 4 0 4 4 0 1 10 1 4 1- 1 6 0 0 1 Chondria tenuissima 5 0 0-0 1 1 0 0 0 1 'O O O 1 6 0 0 0 1 1 1 Chondria dasyphylla 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 T 0 T Polysiphonia denudata 0 4 0 2 5 2 6 1 1 0 5 1 1 5 0 2 I I 2 2 2 ~ Polysiphonia harveyi 58 63 50 50 70 54 60 51 57 11 20 29 19 39 21 20 14 19 58 21 39 Polysipbonia lanosa 86 86 100 44 46 27 81 50 94 80 99 100 39 0 40 98 81 98 68 71 69 Polysiphonia nigra 1 17 0 2 4 7 12 6 11 11 5 1 1 4 1 15 0 2 7 5 6 Polpiphonia nigrescens 19 23 4 15 15 20 55 10 20 25 17 '1 4 11 '4 49 7 '14 21 15 18 Polysiphonia urceolata 42 20 23 27 24 5 29 4 13 26 18 24 7 0 0 36 6 2 20 13 17 Polysiphonia elongata 0 0 0 0 0 0 5 0 0 0 0 0 0 0 0 1 0 1 1 T T' '
Polysiphonia fabrillosa 5 1 0 2 4 0 2 1 1 0 1 1 1 1 0 0 2 0 2 1 1 Polysiphonia llexicaulis 0 0 2 0 0 0 0 0 0 2 7 -1 2 1.0 5 h o T 3 2 Polysiphonia novae-angliae 60 62 73 58 70 60 6R 57 64 80 85 81 77 99 75 87 70 75 63 81 73 Rhodomela confervoides 14 8 2 to 5 2 6 5 10 1 2 0 2 0 0 1 2 4 7 1 4 21Umi Operation 3-Umt Operanon Summanes Phaeophyta GN RP MP H Q FS WP SE SS GN BP MP H Q D WP SE SS '211 31 Jg Ectocarpus fasciculatus 17 20 48 33 27 10 20 20 15 17 27 10 39 5 1 21 17 15 22 18 20 Ectocarpus siheulosis 49 38 25 50 44 37 45 35 29 48 31 26 3o 24 23 45 32 19 39 31 35 Ectocarpus sp. 2 6 17 13 2 4 2 4 8 2 1 2 1 -0 0 'O l- 1 o 1 3 Giffordia granulosa 2 4 8 6 5 2 2 1 4 5 1 2 8 to .I 6 2 0- 4 4 4' Giffordta mischelliac 18 13 6 8 32 15 25 6 6 23 21 12 17 56 11 20 1 1 15 18 17 ' Pilayella httorahs 65 7 6 21 6 58 20 7 6 40 5 1 26 5 51 20 5 8 23 18 20 ' Spongonema tomentosum 17 20 10. 17 12 5 11 13 11 13 8 11 12 13 7 12 12 7' 13.11 12 ' Entonema accidioides 0 2 0 0 0 0 0 1 0 0 0- 0 0 0 0 0 0 0 1 0 T Acinetospora sp. 0 1 0 0 0 2 0 1 0 0 0 0 0 0 1 0 0 0 1 T T l Teldmannia sp. 0 1 0 0 1- 0 0 0 0 0 0 0 0 0 0.0 0 0 'l 0 T ! Ralfsia verrucosa . 76 58 42 15 61 60 68 27 42 ' 73 M1 67 69 11 70 79 61 51 52 62 57 Elachista fucicola 70 62 69 58 61 45 61 73 54 76 76 71 70 SM $7 73 80 63 61 ov' M 'i llalothnx lumt ncahs 1 4 0 0 0 0 4 0 2 2 4 2 4 0 0 0 0 0 1 1 1 Leathesia difformis 12 1 27 4 14 1 12 1 4 25 8 25 12 5 11 15 1 .1 8 12 10 - Chordaria llagelbformis 15 23 27 15 5 2 27 12 7 2 25 12 10. 1 0 6 1.-l' . 14 6 to Sphaerotnchia divaricata -0 1 2 4 0 0 4 4 1 0 1 1 1 0 0 0 0 0' 2 T 1 Cladcmiphon 20sterae 0 1 0 0 0 0 0 0 0 0 0 0- 0 0 0 0 0 0 T -. 0 T Eudesme virescens 0 0 0 0 0 0 0 0 0 0 0' O O O O 1 0 0 0 T 'l Pogoinchum fikforme 4 1 4 4 0 2 5 1 1 0 1 0 2- 1 0 I o 1 2 l. 2 Desmotnchurn undulaturn 7 6 0 0 0 2 5 0 4 5 4 0 M 5 1 l' O 1 3 3-Phaeosaccien colhmn 1 0 0 0 0 1 1 0 0 0 0 1 1 0 0 1 0 1 T I 'l Punctaria lanfoha 5 5 2 10 2 11 3 5 4 2 5 1 6 5 4 4 4 4 3 ~4. 4-Punctana plantaginea 5 4 4 0 0 8 7 0 1 11 2 0 1 0 o 1 0 0 3.2 3- i Petalonia fascia 54 74 63 46 54 56 70 55 38 61 6M 60 64 48 57 61 50 37 57 '56 56 Scytosiphon lomentaria 64 74 48 4s 49 64 60 49 40 - 50 58 55 45 39 55 52 42 30 So 47 51 Delamarca auenuata 0 0 2 0- 0 I O O O- 'O O O O O O O O O- T 0 'l .; Desmarestia aculeata 2 1 4 13 5 10 17 5 11 12 1 1 21 u a 15 11 10 7 8 6 Desmarestia vindis 12 17 17 25 8 11 17 8 19 13 7 ~ 13 26 ' $ ' 11 ' 19 13 18: 14. 14 14 , Chorda fitum 2 'l 0 13 1 '1 11 4 4 1 2 1 14 0 0 -12 5' 7 4 5 -4 ,
~
Chorda tomentosa 0 4 2 23 2 4 6 4 8 2 5 2 27 0 1 5 7 .7 5 6 6 Laminaria digitata 0 0 0 13 0 0 0 0 0 0 00 7 0 0 0 -0 I- 1: 1 i - 1aminaria longieruns 11 4 13 42 1 1 19 14 14 .7 0 7 62 0 -5 25 .18 21 12 16 14 ,
~ Laminaria sacchanna 62 69~ 63 % 60 50 61 62 54 71 76 70 88 39 :48 75 .73 51
~
h2 ' 06 64 . Sphacclaria cirrosa 49 25 10 6 49 27 18 0 . 4 ! 65 17 7 0 75 52 25 8 2 .22 -28 25. Sphacclaria rigidula 0 0 0 0 0 0 1 0 0 2-0 1 0 0 2 0 1 0 'T 1 T , Ascophyllum nodosum - 100 100 100 100 79 100 100 100 100 100 100 100 100 57 100 100 100 100 97 95 90 -) Fucus distichus s edentatus 6 7 13 23 l' 6 2-7 1 2- 5 10 17 1 0 4 t. 2 7 5 n'. ] Furus distichus s evanescens 11 12 2 23 . 6 6 8 10 12 2 10 7 14 0 0 2 4 4 '10 5 7 i Fueus spiraks _ 5 33 8 0 0 1 4 2 l 8 46 29 4 0 0 0 0 '4 6 lu 8 fueus veuculosus 100 100 100 100 82 .100 100 100 100 100100100100100 im 100100100 98 100 '99-Sargassum fikpendula 0 1 0 0 0 0 0 0 0 0 0 0 0 M 0 0 0 0 T 7 '4. Rocky Interiidal 61 l
i TAllLE 2. (cont.) i 2.Una Opera 0on 3 Una Operanon ~ Summanes -l Chfomphyta - Q{ pP Q H E D M g SS ON llP MP TI' g $ M & M M $ g Utothrix Dacca l 37 37 27 17 32 29 45 31 24 40 32 31 3n 18 31 32 26 2n 32 30 31 l Urospora penicilliformis 38 42 40 33 31 21 43 31 24 35 45 36 27. 29 33 31 31 17 33 31 32 Urospora wormskjoldii 5 8 6 0 7 4 7 2 0 12 5 '6 2 24 8 13 4 4 5-9 7
'Uros[nra collahens' 6 6 6 4 4 1 2 2 6 0 4 0 0 2 0 1 0 0 4. I 2 ,
Acruchacte viridis 0 2 6 0 0 1 0 0 0 1 1 0 0 0 0 1 0 0 1 T I l Monastroma grevillei 26 23 19 19 23 32 23 15 25 20 21 18 27' 1 19 19 20 21 23 19 21 ' Monastroma pulchrum 32 33 25 29 24 23 33 33 31 20 19 23 30 5 24 26 26 25 - 30 21 25 l Monastroma oxysperma 0 1 0 0 0 0 0 0 2 0 1 1 1 0 0~ l 2 7 T- 2 I ; 5pongomorpha arcta 29 27 31 25 18 4 18 to 7 19 12 32 18 5 6 12 7 2 18 13 15 ! Spongomorpha seruginosa 10 5 15 0 6 6 8 5 1 N 14. 17 5 1 2 7 o 5- 6 7 7 'i
'Codiolum gregarium' 1 0 0 0 0 0 0 0 0 0 0 0 'O. 0 0 0 0 0 T 0 T '
Capsosiphon fulvescens 1 .I 0 0 0 2 6 0 2 0 0 0 0 0 0 0 0 0 2 0. 1 , Capsosiphon groenlandicum 6 . 20 8 2 2 2 5 2 5 0 1 0 2 1 2 1 1 1. 6- 1 3 Bhdingia minima 61 55 71 71 70 8 64 43 62 67 68 89 83 81 49' 70 00 83 55 73 64 ' -]
' 11hdingia marginata 1 2 0 2 4 1 4 1 2 4 1 0 0 0 0 0 0 0 2 1 I Enternmorpha clathrata 27 4 10 4 25 33 33 1 14 18 14 6 0 ' 14 21 23 4 14 ' 18 13 15 Enteromorpha flexuosa 38 40 35 27 63 37 54 12 33 63 50 58 42 85 40 60 30 49 38 53 46 Enteromorpha intestmalis 52 39 40 19 32 27 $5 15 30 38 36 30 15 19 20 39 18 35 35 28 31 Enteromorpha linza 50 74 75 40 71 35 67 48 42 68 ' 85 So 55 83 60 73 50 32 55 en 61 Enteromorpha prolifera 42 37 35 40 35 35 54 15 40 21 12 10 10 15 15 23 12 20 37 15 2n Enteromorpha torta 5 1 2 0 .1 6 6 0 2 1 0 0 1 1 1 2 0 0. 3 1 2 Enteromorpha ralfsii 4 1 0 0 4 8 4 0 0 5 0 1 2 1 7 2 2 0 2 2 2 Percursaria percursa 4 1 0 0 1 8 4 0 1 0 1 0 0 0 0 2 0 0 2 T. I Ulva lactuca 9n 90 96 94 90 89 98 86 86 93 vn 95 90 90 92 95 93 88 92 93 92 Prasiola stipitata 51' I 4 90 1 1 0 75 8 61 0 0 92 l- 0 I 7o 44 24 31 27 Chaetomorpha linum $6 81 88 79 69 ed 75 79 85 n2 no 57 71 11 52 t1 eo 76 75 no n7 Chaetomorpha melagoruum 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 T T T Chaetomorpha aerea 23 26 29 2 74 40 45 2 10 $5 3s 65 x 7: 52 no ? U 29 44 37 Cladophora albida 5 4 4 0 6 8 14 2 6 1 1 1 0 2 5 2 0 0 o 1 4 ,
'Cladophora ficxuosa' 8 26 31 17 13 11 19 17 12 19 32 29 18 19 29 39 23 27 16 2n 21
'Cladophora glaucescens' O O 2 0 0 0 4 0 0 0 0 0 0 0' 2 1 0 0 1 T T '
Cladophora lactevirens 0 0 2 0 0 1 2 1 5 0 0 0 0 0 0 0 o 1 i T I
'Cladophora refra:ta' 8 37 23 8 18 12 24 17 12 1 6 6 2 o 5 4 6 1 18 4 11 Cladophora sericca 24 20 13 2 40 32 40 11 20 35 17 14 5 25 43 33 5.'23 24 22 23
'Cladophora crystallina' 0 0 0 0 0 0 0 2 0 1 0 0 0 1 1 2 0 0 T I T Cladophora hutchmstae 5 1 10 2 13 7 12 2 11 10 4 10 1 5 o 4 2 5 7 5 '6 -
Cladophora rupesms 2 2 2 4 2 4 4 0 2 1 2 4 2 8 5 5 1 4 2 4 1-Cladophora ruchmgeri 0 0 0 0 1 0 0 0 0 4 5 4 0 19 18 11 1 1 'l
- 4 Rhiznclomum riparium 29 19 8 6 19 49 29 to 10 31 10 8 4 5 20 20 8 2 21 12 In
'Rhtroctonium kernerf 2 1 0 0 0 1 0 I i 4 0 0 0 0 I 'l 1 0 l i I i llhizxlomum lortuosum' 1 0 0 0 2 0 1 0 0 0 0 0 0 0 0 0 0 0 .I O T r Dryopsis plumosa 7 5 0 6 19 4 5 6 4 2 2 2 n 21 2 4 0 4 n s n <
[1ryopsis hypnoides 2 4 4 0 4 6 1 1 4 10 2 2 8 17 7 to 5 5 3' 7 5 Dertuia marina 6 2 0 2 25 7 0 0 2 1 0 0 0 5 0 1 0 2 5' 1 3- .( Codium fraple 81 85 83 100 100 67 81 64 69 92 81 86 88 100 98 96 75.80 83 88 86 i 7 62 Monitoring Studies,1993 y y -. 9 W'- ,
,'i 1 l I f i
.l 40 - - 40 50 - - 50 c 60 '- - 60 e'
E II l 11 Ill E70 - f . - 70 ,
.i Iol Ibl 80 - - ,
I '- so I , 90 - - 90 4;0 % 0 4J N:o Oo %? #c? CpJ Cp? 'SJ 'S? DJ D? ^Es Es Et Et 'eJ J J ? ? J J' J ? P Fig. 3a. Clustering dendrogram of percent similanty of qualitaine algal collections. by sia! an and operational perud (2 unii 3 unit).
- m. -m ,
- a. -a w- . so ,
Ijac - .o
.- I 11 111 h- i , . . ,o E
h I so - ; , . .o
, i
- 9. - . go
' Fig. 3b. Clustenng dendrogram of percent similaniy of qualitative collecisons. by year, at Fox island-Exposed.
Rocky intertidal 63
t Abundance Measurernent lowest at FE (249.) and highest at GN (779); minimum cover was lowest at FE (12%) and A variety of interacting physical and biological highest at GN and FS (43G). Low intertidal processes influer;ce abundance and distribution of (Zone 3) maxima during 1992 93 ranged from 1% rocky shore organisms. In the local intertidal (FE) to 38% (GN): minima were lowest at FE and zone, these include tidal fluctuation, degree of MP (0%), and highest at GN and SE (6%). exposure to wave energy, annual cycles in many Relationships among barnacle abundance physical parameters (e.g., light, nutrients, air and patterns at NUSCO study sites (excluding FE) water temperatures), predation, competition, have been remarkably consistent over the study reproduction, propagule transport and behavior, period, including the present sampling year. and recruitment. Much research has been Variability among study populations has been conducted describing the effect of these processes considerable and primarily attributed to natural on community organization, both singly and, to factors. Degree of site exposure to wind and waves some degree, in combination, as reviewed in and slope of available substratum appear to be the NUSCO (1993). The purpose of these quantitative most important controlling mechanisms and their. studies was to sample organism abundance over an effects on local barnacle population dynamics are { area cufficiently large to accurately Jescribe large described in detail in NUSCO (1993), 1 scale patterns of abundance at each sampling site, These natural controlling mechanisms play an to relate these patterns to site-specific physical wd important role in community organization at our biolagical controlling mechanisms and, of primary study site nearest the discharge (FE) as well; concern, to determine if any of these mechanisms however, the effect of periodic thermal plume lesult from, or are influenced by, the operation of incursion is superimposed on these natural MNPS. Subsections describing abundance patterns mechanisms and has resulted in significant impacts - of important intertidal organisms, i.e., barnacles, to the shore biota there, including barnacles. Duc Fucus, and Cnondrus, are included below. to the influence of tides, these impacts are most - notable in the low intertidal (Zone 3). Zone 3 Barnacles barnacles are exposed to elevated. discharge temperatures for 910 hours each tidal cycle during i Intertidal barnacles (primarily Semibalanus 3 unit operation,whereas barnacles in Zones 1 and l balanoides) occupy much of the pnmary space on 2 are exposed to air during times of maximum 3-l local rocky shores and are most abundant in the unit thermal plume incursion. These conditions mid intertidal (Zone 2). Barnacle abundance also have directly and indirectly modified the pattern of ) varies seasonally through an annual cycle of barnacle abundance in Zone 3 at FE. Elevated l reproduction and settlement in early spring, rapid temperatures directly impacted low intertidal growth and increases in surface cover in summer, barnacles by causing complete population mortality and cover decreases through autumn and winter in late summer every year since Unit 3 start-up, due to competition for space, predation and including the present study 3 car. Reduced early physical disturbance (Connell 1961; Menge 1976; summer maxima is an indirect effect of 3 unit i l L Bertness 1989; NUSCO 1993). conditions and resulted from the development of i Barnacle and predatory snail abundance patterns an extensive low intertidal Codiun fragile at eight sites in the Millstone area are presented in population at FE, which persists to the present. Figure 4 as time series covering the fifteen year As with Chondrus at other sites, Codium and ; study period (1979-93). At all sites, and in all associated silt accumulated on adjacent areas three zones, the annual abundance cycle was exclude barnacles and other species from Zone 3 characterized by minimum coverage in late through preemption of habitat space (Underwood winter /early spring and maximum in summer, and Denley 1984; NUSCO 1993). The return of Maximum barnacle cover in the high intertidal- predatory snails Urosalpint cinerca and Anachis (Zone 1) during 1992-93 ranged from 4% (GN) to lafresnayi in recent years to pre-1984 levels (Fig. 45% (FE). Minimum coverage in Zone I ranged 4), coupled with other impacts mentioned above, . from 1% at FS and GN to 22% at FE In the riio may have also contributed to reduced barnacle intertidal (Zone 2), maximum barnacle covet was abundances observed in Zone 3 at FE. M Monitoring Studies,1993 l
100 - Unit 3 start up 90 BP 60; . 70< 60 30 40
^ f A , /
~ <\ I /\ /\ /\ n ,'r . !'\. l'N /3 /
h*x- <. Q.u /%.J %I \_%lB('t'V
' Y% j x;'f "4 't\ p.;. N
\ l . !*-(-f y\l
;.. .hl \ --l I
\/ l \ {\ ,
s
,.p l l l J
... .a _ s _ _ _ ,., u. a _
Alu s.,
"Ll'
_ a _ ,., _ s.O _ ,., ... ,., w ,. o u
~
,.o _ ,o 1979 1980 1981 1982 1943 1984 198$ 1986 1987 1988 1989 1990 1991- 't992 1993
....... sone 1 sone 2 --- tone 3 _ prodotors 100 Unit 3 stort.up 2nd cut 90 FE openea 80<
70 , 4 ?- f 60 s. .' 50 ,*- . . ./ 4
,-t ~ \ ,, ,
40 .'g - l g 30- It - f /\ h(t . { s I l's l 1 l\ \ l t' s ,) !\ 1979 1980 k! k'! 1981 I 1982 1983 lk \Y 1964 1985 t uor se, por seg us sep uor $,p uve- Sep w a< 5ep _ 5ep uw See por Sep War Sep um Sep u2r Sep uw Sec uor Sep me Sep 1966 l5! nebul\!\ - a 1987 1988 1989 1990 - 1991 1992 1993
......- rone t zone 2 --- Kone 3 1 prodotors 100- Unit 3 stort-up 90- FS 80 70 - 3 ,k 60 [g en - so .
v ,g n ,
.7 , , ,\ s ,8 h 4Q. *I t r f\ ' \ \ fs I l\ . 1 l\\ l\
l l i 30-l\ ,I \ ! \ l \ l\ l'\ l' \\ h y 2010- /\ i \ J I l ll \\ s l'# r s n i lI\ \
\
l \ li \\, s i fa
' t I
' 6 l.
\
l\ * ; l \ ! \ I i t I I t =' i~ h , _' , \ g g i
} e
- 4. l f e. \ l \,,i ' \ l '.
? \ lt
- gf '
2: l y \ 10 \ il\ b\ 1l. l Ih %t '. lf. \ lI'- Nll % 1 ., \ ,,8 0:. .. A .
\I? , ; .
~,f
.i
- f ,,g .N l , - l _ , .' l\ f jg ', f. l_,
us Sep mer $ep uor seg uo, sep wa see _ 5, _ seg uos sep we, see uo, $,, nor sep vo, Sep vor $,, nor $., uo, sep 1979 1980 1981 1982 1983 1964 1985 1986 1987 1928 1989 1990 1991 1992 199)
....... sone 1 tone 2 --- gone 3 . pr eootors 100< Unit 3 stort.vp 90 GN BO.
70 ; 60< g 50 40 - < n< l \, n rs us
. ~
- i. e t tv I \ ,' 'Y '
l l l Y ' ' 4 l\ , I t
\/ - - -
j j i
' , , , ,- '.'j 2l g]gj \j A -- a
\,
v
- n. .>
- a. ..%. . . .. , ... nA. ;A _ ._ .>
une sep w seg ua, s., w s ee . ua, sep wee sep wae sep we, sep wo, S , uo, see vor see so, ser use 50 we, 5., we, S., 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993
....... rone I rone 2 --- sone 3 - ; preootors flg. 4 Abundance of barnacles in each tone, and of predatory snails in Zone 3, of undisturbed transects. from 3/79 9%
Rocky Intertidal 65
100- 1,tmt 3 stort-up 90 MP 80-70-60
- 50-40 /s ,} ,
30- !\ :K p '. t <. \
- b. ft . > M ;l ,\\ \
20 - '\ ?. . l ' 'h . ,. .t
" 'i i!\ ii \ ' t}t \\' '..:'l \.i f$t \v. lJ Y' ' I'l p\\
\*
10 - \\
!s's
.\ t g \\ ? .
ll[.. lt)t. t t \ ; \u .a s i i;lE{,Nl INN'O] u.r sep u.e lb & fds
~
W.r 5., we s., w 5., r 5., s., u.< se, u. 5.s e 5e, uo, 5., n..r se, uor 59 u.r 5., u., se, u.e se, 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993
- - - - - - - tone i rone 2 --- rone 3 preootors 100- Umt 3 stori-up 90 SE 80 70 60- . ,s s
b 'n 0-l\ \ 30- le\ , 8 y 20- s t# i n Isr - :s . s s
< - -r s in
\-: . k- - <. ,
3 t 'Oi 7 % .;. oi r - ly c
's : <\.. 's l\_ ,' \ :/> ; ,,' -. 'fs, f r r\ .
s- i ,-_l \, i l s , s a- ' '\a*so/5,f \-~ if N'\\. fx.\N ' i/ ..f\ 4- s i i i s 5 s si~ o s a s
' ' ' 't e '\ ,
r s"u
\
ivr 8 o' 's i 's i x i < '\ t'PN; A- - ? b' ^ b' ,/ o}5 N- h Y-, A s., s., - _
- s.,
m
. s., ...
w _.WL' s., m. s., . s., - s., -. s., . s., ... s., s., ... s.,
"s.,
1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993
------- zone 1 tone 2 --- torse 3 : , preootors 100- g,ut 3 start-up 90 SS 80-70 -
e0 - .i a 50 - E 40 3 30- P e 2 ) '\ d 'r'i !\ ^ . .' ri.. t l i- ~
'0 -JV,'b .y/ \
l,'. . f,y\.y ,l,Q
~ ,s. j ! ', l -
l4 l \, ;l'j ,j't h,.~ ,/,i%G,-
,- \,lq> .. ie y
u
~ ..
v se ha .,.MU/A
, 5., s., 5., -
. s.,..s. _.w.' A s., _ 5., ~ s., ..e s., -
A 1 's. ,,, % . m e ?t 5., . s., - s., , s., - 3., ... s., - 5., 1979 1980 1981 l982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993
- - - - - - - tone I tone 2 --- rom 3 .- _ preootors 100 - Urut 3 stort-up 90; WP ,
80-70 so - 5 50 - 6 40 ;
- x. A A l' * ,
3 20 40% ). Similar, species are often outcompeted for space by another ahhough less marked, increases in Fucus, fuccid, Ascophy//um nodosum (Schonheck and abundance in recent years have also been observed Norton 1978, 1980; Keser and Larson 1984). At at BP, SE SS and WP. which may indicate an both sheltered and exposed sites, maximum Fucus area. wide trend not related to power ' plant abundance typically occurs in late summer /early operation.
autumn. Local vertical distribution patterns of intertidal Fucus are determined, in large part, by Chondrus and common epiphytes mechanisms similar to those discussed for barnacles (i.e., related to exposure to waves and As discussed in previous sections, power plant ,
slope of available substratum) and are discussed in impacts to the local rocky intertidal have occurred -
previous reports (NUSCO 1992, 1993). primarily in Zone 3 at our sampling site nearest Physical stress from the MNPS discharge,in the the discharge (FE). Documentation of abundance form . of heat, is an important enechanism patterns of the dominant low imettidal alga, -
controlling Fucus abundance in Zone 3 at FE. Chondrus crispus, and its associated seasonally _
Elevated temperatures during periods of thermal abundant epiphytes (e.g., Monostroma spp. and plume incursion have resulted in annual Polysiphonia spp.) is therefore critical to our elimination of Fucus in Zone 3 since the opening assessment of these impacts.
of the second quarry cut in 1983 and throughout 3- Chondrus abundance time-series are presented in unit operation, including 1992-93 (Fig. 5). Figure 6. Perennial populations of Chondrus have .
Thermal stress was most severe at FE in Zone 3, occurred in the low intertidal at all study sites, because organisms there were sebmerged and excluding FE. Abundance maxima at these sites exposed to elevated temperatures for much of the during 1992 93 ranged from 10G at FS to Rocky Intertidal 67
100- Unit 3 start-up 90- BP 80-70-60 S 50-g 40 g 30-20-10- ,qs
%" ..,, ^ *f ;
0;*Y^ " -z e b ^ h - - * - * - * * *
- UN '
un s.o - see uae se uor s., war 5., war see u s., uo, sep ue see ver s., uo, sep uo, s.o uo, s., uor see uo, sen 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993
------. rone 1 tone 2 --- 2one 3 grczers 100- Umt 3 stort-up 2nd cut 90 FE coeneo 80-70-60 * ** S0 , ,
b 40 j "' . B '
& 30 ! '\ ;".l l y 20 . 4 t 'o i
*n .. i
't?1' '% mvtD%, G ,
lft a [i I Qr ! ti /
\
\} g_ l
- u. .. wer s.. _ se. _ s., _ ,, u., 5.. _ s., _ s.. _ s _ 5., _ .. -5 _s.,_,..~,..
1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993
------- sone 1 zone ? --- zone 3 - groters 100
- Umt 3 stort-up 90 FS 80-70-60-g 50 M
$ 40
, /
2 /
,% s s ~ 's,/
, Ir G' m /
\ !N\1rY\%, s t ,'
10-
\ mt p%;
\ l^\ % N .,/
.A. A g -
1, D. - - - - - - - - - - - - ~- - ~
- _ - Sep
- - uor
- -5 s uo' 5eo war seg uor See War Sep wer Sep war See Woe feo Woe Sep uor Sep uor Sep uur sep uor See us Sep 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 t990 1991 1992 1993
------- f orm 1 20ce 2 --- Ioae 3 . grazers 100- umt 3 stort up 90; GN 80; 70 60 -
- 50 h 40-g 30 -
* * /s # - s\^
M 20 '. [ %j \ 'e g M a
- r 4 ^
%/ g e- p- /
g 10- y' 3 s x . p.,3 rN yi V\ t/ N
\
\
iMd7Od 0-un see uo, see uae sep uor --sep f~ ~ ~ 9,sT5.M$, /vy N 'h' A O' N
~ -
_- 5ep wer beo _ 5ep W e*. 5ee per Sep wo< 59 ma, Seo Me, Sep une see uo, Seo u ,o Sep 1979 1980 1981 1982 1983 - 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993
------. rone 1 rone ? --- ror,e 3 : grozers Fig. 5. Abundance of Tucus in each zone, and of grazing snaih in Zone 3 of undaturted transects. from 3/79 933 1 68 Monitoring Studies,1993 e
I00 - , Unit 3 start-up 90- MP 1 60-70 - l 60 -
- l. 50 -
l 40 l 30 < 1 20< l 10 e,& #xtv\ 4 % 4 tN* , f ,
- l. 0-
\ ,-s o- -- -
- -- ( - - - -
. e -
.h*f -
/
War Sep has nep uw hop Mor Soy We bop kor %ep une 3ep wee Ley wy %ep .ee las We See Me %ep Wer Sep war Sep - twp l 1979 1980 1951 1982 t981 1984 1955 1986 1987 6988 1909 1990 1991 1992 1993
-----.- sone i sone t --- none ) - --. grow.
l 100 ' Unet 3 stori-w I co- SE 60 - i 70 ' l 60-5 50 fg 40 30 - - (,
/
t1 20 ,M b A' ( "g'"*~ / n s's [g \ [\/ 10 fj 4,
'f w!V t & % 'f! s\ . ,'
i
'\r g v
~f l
\ \,
/ ,/s lg\/ d q % ' Wg s
l Y !\:_.V * <. 2 1.1 4 \ h 4
.f i A *-
t 4 g, .i . e\ Stwe(N*hM* l i \/ , */s Qdky/ g/.4.;,',A.f ...' \,'2)9*( ,-; / \ i,,, ,A , s.p ... .. . ,e. - - - se. . se, - , . . . . .., ,4. r .. ..r ,e. ..,e. . ,.. .. ,ep ... se. 1979 1980 1981 1982 1983 1984 1985 6966 1987 1968 1959 1990 1991 1992 1993
-.-.--- tone t torie J --- aone3 _ _ grcrets D' Unit 3 stori %p 90- SS 80-70 f,0 ,
30
.or he mee top ww isp uor Lee we bop use Sep wee see mer See wa See wo+ 5ep hos Sep - %se us top was too une See 1979 1960 1951 1982 tone i 1983 1984 1985 rone 2 19P6 1987
- .~ - sone 3 1988 h 1989 1990 1991
. grome 1992 1993
-)
l M' Unit 3 stort %p to: WP 80 70 to . E 50 g 40 r to , %. , a ,, v
. / ' /
** ' / I
....-----................p .
1979. 1980 1981 1942 '1983 1984 1985 1986 - 198? 1986 1989 1990 1991 1992 1993
...---. rone 1 fone 2 --- gene 3 ; _ grosers ng. 5 (coni)
Rocky Intertidal 69
100< Un.t 3 stori-up - 904 BP 80-70-60< ,4* A f., . . . . .
,' *~/\
e sn_ ym . >(*.-~.*,,.- '~,
\5
* ' 'O
\ ..;
h 40 t
'i ~~
/ \,
30, SO '. 10 8{/ kI[% 'n7-' t
's]
i e .]
/g s +
/\
# \
y l
/
%. ;i j
,b, '
$\
f ph
-' 'l I
\
i i lA'y g
'b*
2-q \ f ' \ pr %
' \
( l f ' g ' I \ l
\!
\/
\ o s
l\ ^\ \
, \ >- \l \l r sf 0 ./ t -/ t -! \f \ \-
har See Mor See Mar Sep har Sep War Sep Mer Sep War Sep Wer See Mar Sep Wer Sep Mor ben War Sep Mor See War Sep War Sep 1979 1980 1981 1982 1983 1984 1985 1986 . 1987 1988 1989 1990 1991 1992 1993
------- Choncrus Monostromo --- Polysiphoruo 100' 2nd cut Umt 3 stort -up F0 onnd 90 80 '.
\. - .! a ,,
- - ,7 q . .* 4
(;. . . g. n,, 3,. v ..A p, i f I I \ is , i i , 30 I { l' I
'y 4
t 0\ \ td 1 I s t \ I \ \ i t
/\ t \ l It
\ ;"1 I a
sq: \ A'r [y\ \j r/ \r'/N/ % \\ ll Jfs' ' \/ \ ,) \1 \ \'Lf g 10 \ ,s f\ i
'l 1
% j \ f g i n J %'
Y /\ \/ 4" l V l \ \ l
\ l
; \/ it 4 1 2 g \ \ \ : * '
l ! !? , 1- ' \q ' ! I \ *-
, [ -
g,J LJ j Lp gs a ps_ .. - ' - - .t her See War Sep war Sep w Sep Mor See War 5+p woe See Mor Seo Mor See Wer Sep wer 5ep uor Lep por Sep wer Sep Wor Sep 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993
------- Chonorus MoncStromo --- Polysiphonic 100 < Umt 3 stort-up 90 FS s 80
} 70 + 60-
- S0-f 40 -
30-g 20 10< j , f p,,,, , ,
, , , , , 'j- , , , _~' .' ..-.,_ ,
,,,4q ,
'z "g 7
_e.. I h' m l
$.rq , mkl \ k #
I _J a Mar Sep kor Sep Mor 5eo My Sep Woe See her Sep Mor Sep uor See por sep uor Sep sor Sep uor Sep uor Sep uor See war Sep 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993
+--.--- Choncrus Monastromo --- Folys'phoma 100- Umt 3 stort-up 4 90- GN-80 70- .
60 j .- -
- So. 3 !! . f., e ,
a
- 3 ,, . -
- c
f 40 .% j' ' z ,, ! ' 'i ' ' ' u \, ,
. e 30 \1 y '- ' V,
\i ., , o ;
20 ) N, lI- 4 10 e l, j,s f ** l\ *\ 'i l h' e s p \ \ 0- -t i\ h n /
'l\ ik war See per bes uor see war Sep mor See men ses por sep mer ser por see uor Sep uor Sep met Sep uor sep wer See war 5eo DW't, \h-/\ l \ 'h\n t i s
1979 1980 1981 1982 1983 198- 1985 1986 1987 1988 1989 1990' 1991 1992 1993
.------- Chonorus Monostro.no -- Polysipnorwa hg. 6. Abundance of chmdrus and major epiphvte5 m Zone 3 of undisturbed transceis. trom 3'79 9a/3.
70 Monitoring Studies,1993
100- Unit 3 stort-up 90< MP e0 . .- r -
.s-70:
60-6' k
-3. *.
.qi s
., j
....- >x.. ...-s -
5 S0 V I g 40-M*
/
W l 9 '*- 'O'
,\
I lA\ D l's\t
- l\
W j\ \
\ f 4-
\1 i
\ h q \ f m
is , l\ i p\
/ \
~
\
h.
\\
\
\
r
\, I
\,
\
t I I t- i \ \ 0 l
\ t I\ /
J $ I \ l 0- # # ' '*T --
& d '[ d V ='
Mer Sep Wer f.ep uw See uor Sep Wer Sep Wer See Wor Sep war bop Wer See her Sep _' bep War Sep por Sep _d 5ep Mr Sep 1979 1990 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993
--- --- Chancrvs Monostromo -- - Polypphonso 100- Urut 3 stort-up 90- $$
80- ' ' , ts 70 60 c ', *q , ,, , , ..,,..
. (' (j
,7,,*
. 'g -
'r r . f - . -
i so - \ {Y '\
't
\ (1 \ L\; \ I ,\ l ~%!
j. 5 40 30 ;
'\ f ll \,; A, .
\;l 1
\
2
'*0 ; ,. s
/\ q ,l i ,
Y 0
>M,) q Iy\ IL r
$ ,\
j'\ l l' l\ i m l 's' i, j\ I
'M i s l \ !s\ !
2 ,' I 5- 4 I t g f\\ I \ f l
\
' $ \
! t l \ I l
I f ! ' I i 1 I t I \
\
E g 1 \ l \ f I % 1 0 i I -- a 'l ! V - Il '
- iJ Mor Sep War Sep Mor Sep War hep Mor Sep War Sep Wer Sep Mor Sep War Sep War Lep Mer Sep Wee Sep War $ep Wer Sep Wer Sep 1979 '980 1981 1982 1983 1984 1985 1986 1987 1988 t989 1990 1991 1992 1993
-- --- Chondrus Monostromo - - - - PO*ysiphonto
'00* Umt 3 stort*up 90; $$
80 70 ) 60-SO- p 40-v i / 'q t ,, , g 30 - 20; ily ;i i,g '
?-
-y ,
5, ,-
\l 10 ;
g f [L 8' ' A [g is t 0- '1 1 \ i \ ,
- !\ A i'8 l'\
war sep war ses por sea war sep - Sep war seg uor sep mer see war see uor sep wer sep mer Sep uor see uor sep une see
~
n l1 , , '/s'\;'\/ Nf f- 1979 1980 1981 1982 1983 1984 19 8 *> 1986 1987 1988 1989 1990 1991 1992 1993-
------- Choaorus Monestromo - - - Polysiphonto 100 - Umt 3 stori-up 90 wp
' 80 10- .
, , f ._ , -, ~- /
60 .a . ; . .. - < - . v- -
;y!w\ ,. . ,
..yv so . ,
40 ; . 30 - 20 . s\ / W ' ' / 4. 4 ft es /\ g [g3 .. f
/ \ fg I 19 i f \ g I l
r l \l
,p _ ,o - m _ m ~
l \
\ , l '
,.p I
_ s.p _ sep ... -_
~)\ % Li'\. I
,.p r ,.p _ ,p ..r sep _ sep
\
3
..r s., _ sep 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993
------- Chonorus Monostromo --- Poiys4pnonio Fig. 6. (cont.)
Rocky Intertidal 71
approximately 70% at MP, SE and WP. In that described for Polysiphonin spp, i.e., peak-general, Chondrus abundances obsened during abundance is observed during cold water months 1992 93 al all sites except FE were similar to those (late winter /carly spring) and virtual absence is obsetved throughout our studies. noted during warm water months (July-December; Maximum Chondrus cover at FE during 1992-93 Table 1).Afonostroma spp. occurred at every site , was_only 2%, which was within the range of covers except FE during 1992 93 (Fig. 6); peak abundance recorded at that site after 1984 (0-14%), but well ranged from 1% (BP) to 21% (MP). Abundance below those recorded prior to 1984 (40-75 % ). patterns of Afonostroma at all sites except FE in This extensive population was eliminated in 1984 1992 93 were similar to those observed during by elevated water temperatures from the 2-cut 2- previous 2 unit and 3 unit years. Afonostroma has-unit discharge (NUSCO 1987). Since that time, only occurred once in undisturbed transects at FE only a few scattered plants have been observed in since 1983 (< l% cover in May 1988), where spring upper Zone 3 study quadrats; abundance estimates cold water temperatures required for Afonostroma have generally been less than 1%, and declined to rarely occur. , near 0% during each summer. These declines are no doubt caused by elevated summer water Similarity Dendrograms temperatures from the 3-unit 2-cut discharge. which appear to preclude any successful The Bray-Curtis Similarity Index is an analytical reestablishment of the Chondrus population at FE. technique applied previously to qualitative data The low intertidal community at FE is now and used here to evaluate communities in the composed primarily of an extensive Codium Millstone area based on the abundances of all population and persistent populations of species observed in Zones 2 and 3 of undisturbed
- cphemeral algae including U/ra lacruca, transects. The resulting clustering dendrogram Enteromorpha spp. and Polysiphonia spp. This illustrates multiple pair-wise comparisons. This . ,
warm-water tolerant community may also technique is used to compare communities at all , competitively exclude Chondrus from Zone 3 sites over 3-unit and 2-unit periods, and to _i through preemption of suitable substratum. examine annual communal changes at our Power plant impacts are also reflected in experimental site, FE. temporal abundance shifts of seasonal epiphytes. Similarities of species composition among Polysiphonia spp. (mostly P. norac angliac and P. stations in mid and low inter 'dal zones during-harveyi) are common warm water epiphytes on cach operational period are illustrated in Figure Chondrus Ascophyllum and Codium, and also grow 7a. Similarities were highest (>75%) between attached to rock. The annual abundance cycle of operational collections at the same station for all - Po&siphonia spp. is characterized by a late summer stations except FE, indicating a - relatively peak, with cover declining to near 07< by winter consistent species composition at these sites , (Fig. 6.). Peak abundances during 1992 93 ranged throughout 3 unit and 2 unit operation. from 3% at FS to 60% at MP. In general, these Similarities were less for among station f estimates are consistent with those observed comparisons, but were primarily related to natural, throughout the NUSCO monitoring program, factors affecting abundances of Fucus 'and' again excepting FE. Elevated temperature regimes Chondrus (e.g., Groups I,11 and. Ill; NUSCO at FE since the opening of the second quarry cut 1993). Group IV consisted of the 3 unit (1983) have produced favorable conditions for operational collection at FE, which is greatly these species by extending the season of occurrence dissimilar to all other collections. The community. and increasing the levels of peak abundance, at FE during 3 unit operation reflects power plant These temperature regimes at FE have also impacts, and is characterized by the absence of ; allowed Po@siphonia spp to persist through cold Chondmi and higher abundances of Codium and j water months, when these species are typically ephemeral algae. l absent from other sites, including FE prior to To better illustrate annual community responses -) 1983, to separate operational events, including- those J The annual abundance cycle of Afonostroma spp. prior to Unit 3 start up, a clustering dendrogram l (Af. grcrillei and Af. pulchrum) is nearly opposite to was generated based on annual collections at FE 72 Monitoring Studies,1993 ,i
a . g- - 0 30 - to 20 . - 20 x- -x y 40 - - 40 1
=
.g30- - 30 m
l l 60 - I 11 Ill IV - so a 70 - - 70 80 - - 80 90 - - 90 Sp S #
'eJ J p? QJ Q? Cp J
C p? 'e? %J %? %J %? Os J O.o
?
5J 'S? Fig. 7a. Clustenng dendrogram of percent similarity of undisturbed communstws. tw station and operational perKd (2-unil 3. unit)
.m. ..a
.w. ..m 30 . .to
?
0 .O 90 - . to F
- n. . to a
- m. .x a
40 40 5 .o . I 11 Ill .w M. 60
- w. . to M. I .u 1
DG . .M .
's 4
's 'se, 's . 'se, 's, ' 's, 'sq 's,, 's _
's,, 's 'sp, 's, Fig. 7b. Clustenng dendrogram of percent simitansy of undaturbed communities, by year, at Fox IsLindhi xsed.
Rocky Intertidal 73 _. l 1
-. - .. - - - -- - -.. - .- . - ~
(Figu c 7b). This method showed three groupings Growth at th 509c' similarity level. Group i represented an u.. impacted community at FE and consisted of. Ascophyllum growth, or annual tip clongation
- annual collections made before changes associated described by the a parameter in the Gompertz with the opening of the second quarry cut were growth model fitted to the data, is presented in .
observed. During these years (1979-83), the FE Figure 8. Ascophy//um growth during 1992 93 (Fig. community was similar to those observed at other Sa) was significantly higher (P<0.05) at FN (116.3 moderately exposed sites, with extensive Fucus and mm) than growth at both GN (105.9 mm) and WP Chondrus populations and consistent occurrences (97.8 mm). Growth differences between GN and of species such as Afonostroma, Polysiphonia, and WP were also significant. The inflection point of other local annuals. Group Il consisted of annual the growth curve, which identifies the time of collections made during years of maximum thermal maximum growth rate, occurred earliest at FN in i incursion created by 2-unit 2-cut operating 1992 (July 16). Growth rate peaked later at GN conditions. Chondrus was climinated after 1984, and WP in 1992 (July 24 and July 29, respectively). and barnacle and Fucus populations were Growth at GN during 1992-93 was significantly ' eliminated annually in summer after that time until . higher than growth over both the 3-unit (97.8 mm) 1987. This period was also marked by high and 2-unit (90.l mm) operational periods (Fig.8b). abundances of Po/vsiphonia and ephemeral green The difference between growth estimates during 3 , algae. unit and 2-unit operation at - GN was also , Group 111 represented years of community significant. Although growth at WP over the 19927 ) development at FE under the less stressful thermal 93 season was also higher than growth during 3-conditions of 3-unit operation. Group 111 was unit operation (89.0 mm) and during 2-unit distinguished from Group 11 by the return of a operation (90.2 mm; Fig. Sc), the growth difference substantial Fucus population and small amounts of between operational periods was~ not significant. Chondrus and the persistence of an extensive At FN, growth during 1992-93 was significantly Codium population. Other. significant events higher than the 1985-86 2-unit year (90.5 mm), but during this period were the appearance, persistence was not different from growth over the 3 unit , and expansion of populations of the perennials period (Fig. 8d). Growth during 3. unit years at Sargassum filipendula and Gracilaria rikvahiac, FN was also significantly higher than growth species previously not observed in undisturbed during 1985 86. transects. The high level of similatity among Relatively consistent spatial relationships among annual collections in recent years at FE suggests a Ascophy//um populations studied around MNPS relatively consistent species composition, which has have been observed throughout 3-unit operation. ; developed in response to present operating The most obvious and important aspect of these conditions. relationships is the phenomenon of enhanced <4 growth at the site nearest the discharge cuts, FN, Ascophyllum nodosum Studies when compared to sites farther away. Growth characteristics at GN and WP were more similar , Growth and mortality of three local populations during.the entire study period, including 2 unit . of the perennial brown alga, Ascophy//um nodosum, operational years; when differences were observed, continued to be Lionitored during the 1992-93 such as during the most recent sampling year, most - sampling year. Many factors contribute to the often higher growth occurred at GN, the control overall value of this species as a useful and site well beyond any ' power plant influence sensitive biomonitoring tool. An extensive review (NUSCO 1992,1993). Therefore, we attribute of phenological, ecolog! cal and applied monitoring differences between reference sites to spatial' ; variability of natural environmental factors and not ' studies of Ascophyllum is presented in NUSCO (1993). Growth and mortality results from the to power plant operation. most recent sampling year (1992 93) are presented By contrast, increased growth and accelerated j below and compared with results from overall 2 growth rates of FN Ascophyllum plants are j
~
unit and 3-unit operational periods. considered to be directly related to power plant-operation,in particular, to periodic exposure to i 74 . Monitoring Studies,1993 l 4
l 9 t the discharge thermal plume. Water temperatures at FN are elevated 3-4 C for 3 4 hours each tidal cycle when all three units are operating at full , I ,, a) d.,
~~5 h -
power. This level of temperature increase creates near ideal conditions for Ascophy//um growth at f,3/' FN by: 1) cxtending the period of " normal" or pd " ambient" peak growing ~ conditions for local a
',, # Ascophy//um populations (18 21 C; Kanwisher 1992-93 1966; Chock and Mathieson 1979),2) more closely
* ~
- g * '- ~ synchronizing these periods of optimal growing
_ r.mone . ..cionion. _. .i. Nat temperatures with the period of maximum daily
- solar irradiance (June), and 3) elevating
,o temperatures in late summer above normal maxima but below stress levels (22-25 C), increasing plant
- D) respiration and growth rates without exceeding .
1, f" ., +. .2 photosynthate production (Brinkhuis et al.-1976; f, f Stromgren 1977,1981; Vadas et al.1978). Similar .; p / conditions have been implimted when Ascophyllum , growth enhancement has been reported near other j ". C,ets Nuk ggggg3l pgggy pj 3ggg (ygd35 eg 3[, gg76, gg73;
* " " '~
- O 3.un.t Wilce et al.1976).
2-um .... 1992 93 Year to-year variability in Ascophy//um growth has been noted at FN during 3. unit operation and m appears related to the degree of thermal load
. c) produced by the power plant. In other words, -
y ". y - % growth at FN is highest when periods of 3 unit operation are longer or more frequent during the J. , peak growing season (May. November), compared g r to years when one or more unit outages occurs . s" ** during that time (NUSCO 1992, 1993). The degree of growth enhancement at FN during 1992-
.- 2.ou .... E..t iss2 - 93
* * *"Pd*FM"F*
and likely due to the extended outage of Unit 2 during the second half of 1992, m
. d) .jM -
Mortality [, .. {, Ascophyllum plant breakage, referred to here as 3a ..'.f ' mortality, was assessed by examining patterns of f frond base tag loss (plant loss; Fig. 9) and apical dp ug bss Np h; Rg. @. mm loss at M
'.,,,e ror i.i.n, e., . . during 1992-93 (32 9 ) was lower.than mean plant -
.....rnises-es .... " 3 . ,ot _ i992.,3 loss during the 3-unit period (58%) and the 2. unit
. period (529). Similarly, plant loss at FN in 1992 Fig 8. Anophyllum growth: a) dunng 19921993, b-d) 93 was 58G, which was lower than both the 3. unit'-
Preseni year 3-unii and 2-unit operational penods at each and 1985 86 (2-unit) plant losses of 66% and 80%, " "' C9es are the Gompertz growth model Dtted to tip Tespectively. Converseiy, piant iuss at we during icngth data, metuding innection pomis. Error bars represent monthly mean lengths e 2 $E. 1992-93 (62 % ) was higher than both operational _; ' means (58% and 55% during 3-unit and 2 unit periods, respectively). Tip loss at GN was 51% during 1992-93, lower than 3 unit and 2-unit tip' Rocky Intertidal 75
l
.s T "f.-%L L(,
~
y u, . L.W Kx ,
\
' N i- so ,
I iso L N-
= 2s NA %, [ 12s N, %
,,, x r. N i
~
e is ts *%-s , Cisnta Neck Giants Neck o e u % ost one en w a % ora D. ** w h.te oe's
-t g 2-unit p-, $ 3-urut 1992-93 < .y . g 2 - uvu t e- e- $ 3- unit 1992-93
. % K s %\ "
,. s N !
h 30 N % w_ q . y* is Q , { r as ' N14;; '
" 25 i 's N.
\ N
, 8' M
\1
-l
(* N '- is is [! ,,,
,~ r- i trhite Point erhate Pomt e % on ein e. . - % on w v. .
owe oe.
- t. t.t 2-et pes 1- vest i992-93 ~3-q 2 -wa.t y- t- , 3-un,i 1992-93
) ee toc \t
.'s Mli .
,, s , , ,s s
, N l l [
- s. i a 2S ,1 '
,'*.. i 2S N L....
yN g s s N si g
..y. .g ,
% s ., , I "% % \
g~ 'T " f j 80 se ,, ,
" 1 Fox !sland fox island '
e o j
- % on o r. = u , o.. o., s. w co. Oe.
.. ., m inas-se e,, 3 - wa. iver-es s.. . sm isas-e6 res 3.u i iss2-53 Dg. 9. Asco/ dryllum mortality.as numberof remaining tagged Dg.10. Ascophyllum mortality.as numter of remaimng tagged plants, at each station. isps, ai cach station.
losses (76% and 75%, respectively). Tip loss was somewhat higher mortality rates were observed at also lower at FN during 1992-93 (77%) than FN, our sampling site nearest the discharge, than during the overall 3-unit period (839) and the at reference sites. However, these higher mortality 1985-86 2 unit year (90%). As with GN and FN, rates do not appear to be related to proximity to - the 1992-93 tip loss at WP (71%) was also lower the discharge, but rather to the exposed than both operational means; 72% during 3-unit orientation of this site, in contrast to the more operation,75% during 2-unit operation. sheltered reference sites, An area-wide seasonal Ascophyllum mortality studies during :3-unit pattern of mortality has been observed throughout operation, including the most recent sampling year our studies which further implicates wave-induced (1992-93), have revealed no power plant-related stress as a major cause of mortality. During both mortality to populations around MNPS. Overall, 2 unit and 3-unit operational periods, mortality 76 Monitoring Studies,1993
rates were highest during the months of August continued to document shills in occurrence of the through November, when strong storms and high algal llora at FE during 1992-93, which included energy waves were frequent. Many studies presence or extended season of occurrence for elsewhere point to stress from wave action as the species with warm-water affinity and absence or most important factor and report a strorig abbreviated season for species with cold-water relationship between mortality and degree of site affinity. exposure to prevailing winds and storms Shifts in abundance observed only at FE during (Baardseth 1955,1970; Jones and Demetropoulca 1993 were most pronounced in the low intertidal, 1968; Vadas et al. 1976, 1978; Wilce et al.1978; where cicvated temperature conditions were most Couscns 1982, 1986; Vadas and Wright 1986). pronounced. The low intertidal community at FE, We continue to monitor FO, our original which prior to 1983 was unimpacted and experimental Ascophy//um site, for recovery characterized by populations of Chondrus and following power plant induced population Ascophy//um, has been replaced by a persistent climination in 1984 (NUSCO 1987,1993). Some community dominated by Codium, Ulen, individual plants have settled, grown and persisted Enteromorpha and Polysiphonia. Also, populations at FO during 3-unit operation, however, no of species observed in undisturbed transects only at significant population recovery has occurred to FE (Sargassum, Gracilaria) continued to persist date. Environmental conditions at FO created by and expand during 1993.
- 3. unit operation, although less stressful than those Elevated temperatures (2-3'C above ambient) at during 2 unit,2-cut operation, may be outside the the Ascophy//um station nearest the discharge (FN) extremely limited range of conditions required for caused plants to grow longer and more rapidly at successfui tecruitment of this characteristicallyslow that site during 1992-93, relative to growth of L recolonizer. Ascuphy//um at more distant stations. The degree of growth enhancement at FN during 1992-93 was-Conclusions intermediate, compared to previous years at that site,likely due to lessened thermal plume incursion NUSCO Rocky Intertidal Studies have resulting from an extended outage of. Unit 2 for I successfully characterized attached shore biota by much of the peak growing season Ascophy//um identifying variability in population and community plant and tip mortality were associated primarily parameters and relating this variability to the with exposure to storm forces, rather than with influence of site-specific controlling mechanisms. proximity to the discharge.
At most sites, degree of exposure to wave energy (through site orientation to prevailing wind. References Cited generated waves and ability of available substratum (slope) to dissipate the horizontal force of those Baardseth, E. 1955. Regrowth of Ascophy//um L waves), and the character of that substratum, are nodosum After Harvesting. Inst. Ind. Res. the direct or underlying causes of the most notable Stand., Dublin. 63 pp. among. site differences in the occurrence and Baardseth, E. 1970. Seasonal variation in distribution of local species outside the inthence Ascophy//um nodosum (L) Le Jol. in the of MNPS. Trondheimsfjord with respect to the absolute Community differences which could not be live and dry weight and the relative contents of explained by these natural mechanisms and dry matter, ash and fruit bodies. Bot. Mar. occurred within the thermal plume area, such as 13:13 22. those observed in the Fox Island area (FE and Bertness, M.D. 1989. Intraspecific competition FN), are directly attributed to the operation of and facilitation in a northern acorn barnacle MNPS. Detection of these differences was population. Ecology 70:257-268, accomplished by comparison of present population Brinkhuis, B.H., N.R. *e.npel, and R.F. Jones. and community parameters at FE to those 'at 1976. Photosynthesis and respiration of exposed untrupacttd sites farther away from the discharge salt marsh fucoids. Mar. Biol. 34:349-359. i and to those at FE prior to community breakdown Chock, J .S ., and A.C. Mathieson. 1979 l in 1984. For example, qualitative studies Physiological ecology of Axophy//um noJmom Rocky Intertidal 77 - I
L i
)
(L) Le Jolis and its detached ecad scorpioides heterogeneity. Ecol. Monogr. 46:355 393. (Hornemann) Hauck (Fucates, Phaeophyta). NA1 (Normandeau Associatesi Inc.). 1993. q Bot. Mar. 22:21-26. Seabrook environmental studies, 1992. A Clifford, H.T., and W. Stephenson. 1975. An characterization of environmental conditions in . Introduction to Numerical Classification. the Hampton-Seabrook area during the 1 Academic Press, New York. 229 pp. operation of. Seabrook Station. Tech. Rpt. Connell, J.H. 1%1, Effects of competition, XXIV-1. l predation, by Thais lapillus and other factors on Newell, R.C., V.I. Pye, and M. Ahsanullah. 1971. i natural populations of the barnacle, Balanus Factors affecting the feeding rate of the winkle balanoides. Ecol. Monogr. 31:61-104. Linorina linorca. Mar. Biol. 9:138-144. Cousens, R.1982. The effect of exposure to wave NUSCO (Northeast Utilities Service Company). action on the morphology and pigmentation of 1987. Rocky Intertidal Studies. Pages 1-66 in ; Ascophyllum nodosum (L) Le Jolis in south. Monitoring the marine environment of Long a eastern Canada. Bot. Mar. 25:191-195. Island Sound at Millstone Nuclear Power Cousens, R.1986. Quantitative reproduction and Station, Waterford Connecticut. Summary of reproductive effort by stands of the brown alga studies prior to Unit 3 operation. Ascophy//um nodosum (L.) Le Jolis in south. NUSCO.1992. Rocky Intertidal Studies. Pages , castern Canada. Estuar. Coast. Shelf Sci. 237-292 in Monitoring the marine environment 22:495-507. of Long Island Sound at Millstone Nuclear Draper, N., and H. Smith. 1981. Applied Power Station, Waterford Connecticut. Annual Regression Analysis. John Wiley and Sons, Report,1991. New York. 709 pp. NUSCO.1993. Rocky Intertidal Studies. Pages Gendron, L 1989. Seasonal growth of the kelp 49-92 in Monitoring the marine environment of Laminaria longicturis in Baie des Chaleurs, Long Island Sound at Millstone Nuclear Power Quebec, in relation to nutrient and light Station, Waterford Connecticut. Annual , availability. Bot. Mar. 32:345-354. Report,1992. Jones, J.E., and A. Demetropoulos. 1968. Schonbeck, M.W., and T.A. Norton, 1978. Exposure to wave action: Measurements of an Factors controlling the upper limits of fucoid important ecological parameter on rocky shores algae on the shore. J. Exp. Mar. Biol. Ecol. on Angicscy. J. Exp. Mar. Biol. Ecol. 2:46-63. 31:303-313. Kanwisher, G.W. 1966. Pholosynthesis and Schonheck, M . W., and T. A. Norton. 1980. respiration in some seaweeds. Pages 407-420in Factors controllmg the lower limits of fucoid H. Barnes (ed.). Some Contemporary Studies algae on the shore. J. Exp. Mar. Biol. Ecol. in Marine Science. George Allen Unwin Ltd., 43:131 150.
- London. Schneider, C.W.~ 1981. The effect of elevated Keser M., and B.R.1. arson. 1984. Colonization temperature and reactor shutdown on the and growth dynamics of three species of Fucus. benthic marine flora of the Millstone thermal Mar. Ecol. Prog. Ser. 15:125 134. quarry, Connecticut. J. Therm. Biol. 6:16.
Lance, G.N.,and W.R. Williams.196 . A general South, G.R., and 1. Tittley.1986. A checklist and theory of classificatory sorting strategies,1. distributional index of the benthic marine algae Hierarchical systems. Comput. J. 9:373 380. of the North Atlantic Ocean. Huntsman Marine Lubchenco, J.1980. Algal zonation in the New Laboratory and British Museum (Nat. Hist.), St. England rocky intertidal community: an Andrews and London. 76 pp. , experimental analysis. Ecology 61:333 244. Stromgren. T. 1977. Short term effects of , Lubchenco, J.1983. Linorina and Fucus: effects temperature upon the growth of intertidal i of herbivores, substratum heterogeneity, and fucales. J. Exp. Mar. Biol. Ecol. 29:181-195. plant escapes during succession. Ecology Stromgren, T.1981. Individual variation in apical : 64:1116-1123. ' growth . rate in Ascophyllum .nodosum (L) Le Menge, B.A. 1976. Organization of the New Jolis. Aquat. Bot. 10:377 382. England rocky intertidal community: role of Topinka, J. L Tucker. and W. Korjeff.1981. The ] predation . competition and environmental distribution of fuccid macroalgal biomass along . 78 Monitoring Studies,1993
1 l
.i
.i central coastal Maine. Bot. Mar. 24:311 319.
' Underwood, A.J., and E.J. Denley. 1984.
Paradigms, explanations and generalizations in models for the structure of intertidal communities of rocky shores. Pages 151-180in D.R. Strong, Jr., D. Simberloff, LG. Abele and A.D. Thistle (eds.). Ecological Communities: . Conceptual issues and the Evidence. Princeton Urtiversity Press, Princeton N.J. 611 pp. Vadas, R.L. M. Keser, and P.C. Rusanowski. 1976. Influence of thermal loading on the ccology of intertidal algae. Pages 202 251 in G.W. Esch and R.W. MacFarlane (cds.). Thermal Ecology II. ERDA Symposium Series, Augusta, gal Vadas, R.L. M. Keser, and P.C. Rusanowski. 1978. Effect of reduced temperature on. . previously stressed populations of an intertidal ' i alga. Pages 434 451 m J.fl. Thorp and G.W. Gibbons (eds.). DOE Symposium Scrics. Springfield,- VA. (CONF 771114, NTIS). Vadas, R.L. and W.A. Wright. 1986. Recruitment,- growth and management of . , Ascophyllum twdosum. Actas 11 Congr. Algas Mar. Chilenas:101 ll3. Wilee, R.T., J. Focrtch, W. Grocki, J. Kilar, H. ; Levine, and J. Wilee. 1978. Flora: Marinc ' AlgalStudies. Pages 307 656in Denthic Studies in the Vicinity of Pilgrim Nuclear Power - Station, 1969 1977. Summary Rpt., Boston ! Edison Co. -l l l 1 l l ll 1
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Benthic Infau'na Introduction . . . . . ................................. ... .. . ...... 83 Materials and Methods . . . . . . . . .......... .......... ............... 83 Data Analyses . . . . . . . . . . . ....... ..... .... ... ....... ... 84 Sediments . . . . . . . . . ................. .......... ..... 84 Multiple Regression Analyses . . . . . .. ....... . . .. . .. 85 Response Modeling and Trend Analysis . . . . . .. .. ... . . . . 86 Results . . . . . . . ... ...... . ..... . ... .. .... .. .......... 86 Sedimentary Environment ...... ..... . ...... ...... .... 86 General Community Composition .. . . . .. . .... . 89 Community Abundance . . . . . . . . .. . . 89 Number of Species ..... ... . .... . ... . ... ..... 90 Community Dominance . .. ......... . . ... ... . . 90 Dominant Taxa . . ..... . . ... ... . . . . ... . 91 Cumulative Abundance Curves .. . . . .. . . 97 Discussion . .... . .... . .... . . . .. . . . . . . ... 98 Conclusions . ........ . ...... .. . . ...... . . .. .. ... 99 References Cited . . . . . .... . . ..... . . . ... .. .. . 100 1 I 4 i l l l 1 l 1 4 II 13cmhie Infauna 81
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Benthic Infnuna j Introduction The infaunal monitoring program at Millstone was designed to measure infaunal species Benthic infauna,in soft bottom subtidal habitats composition and abundance, to identify spatial and - in the vicinity of Millstone Nuclear Power Station temporal patterns in community structure and (MNPS), have been monitored since 1973. abundance,and to assess whether observed changes . Environmental variability characteristic of might have been the result of construction and estuarine systems (Holland 1985; Nichols 1985; operation of MNPS. To date, Millstone studies Holland et al.1987; Warwick 1988; Rees and have identified impacts to infaunal communities Eleftheriou 1989), togelher with our inability to that were attributed to Unit 3 intake construction completely understand how physical and biological (NUSCO 1987) and to 3 unit operations (NUSCO factors combine to impose structure on, and 1988a), as well as regional shifts in species control the functions of, benthic communities composition and abundance that apparently were (Diaz and Schaffner 1990), make long term the result of natural events. This report presents monitoring studies necessary to assess the impacts data collected during the 1993 sampling year, and of human activities on marine environments compares them to results of monitoring local (Thrush et al. 19N). Such studies are the infaunal communities during 2. unit (1979-85) and principal means of characterizing species 3 unit (1986-93) operational periods at MNPS. composition and fluctuations in abundance which might occur in response to acute or chronic Materials and Methods climatic conditions (Boesch et al.1976; Flint 1985; Jordan und Sutton 1985), to variations in Subtidal infaunal communities in the sicinity of biological factors such as competition and MNPS were sampled quarterly (September, predation (e.g., Levinton and Stewart 1982; December, March and June) from 1979 through Woodin 1982; Kneib 1988), or to human activities. 1993 at four stations (Fig.1). The Giants Neck Infaanal studies are an important component of station (GN), located 6 km west of MNPS, is environmental impact studies for several reasons. outside the area potentially affected by power plant Infauna are a source of food for numerous operations. This station was used to identify invertebrate and vertebrate species, including possible region wide shifts in infaunal community - demersal fishes (Richards 1963; Moeller et al. structure and composition which occur 1985; Watzin 1986; Horn and Gibsott 1988, independemiy of power plant operations. The Commito and Boncavage 1989; Franz and intake station ON) is located 100 m seaward of Tanacredi 1992). Sediment rewotking resulting MNPS Unit 2 and Unit 3 intake structures, and is from the burrowing and tube building activitics of exposed to xour produced by inflow of cooling infauna can promote nutrient recycling from the water and the effects of periodie dredging. The sediments to the water column (Goldhaber et al. effluent station (EF), located approximately 100 m 1977; Aller 1978; Gaston and Nasci 1988). The offshore from the station discharge into Long close association of benthic communities with the Island Sound, is exposed to increased water sediments, where most pollutants ultimately temperatures, scour, and to chemical or hean accumulate, also make them an effective integrator metal additions to the cooling water discharge, of short and long term environmental conditions The Jordan Cove station (JC) is located 500 m east - (Diaz and Schaffner 1990; Warwick et al.1990). of MNPS and is considered potentially impacted by l Lastly, because many studies have documented 3 unit operations. The area encompassing this l changes . In benthic communities following station can experience increases in water disturbance (Boesch and Rosenburg 1982; Young temperatures of 0.8 to 2.2"C above ambient during and Young 1982; Gaston and Nasci 1988; Regaault certain tidal stages (principally ebb tide) due to the et al.1988; Rees and Eleftheriou 1989; Warwick et 3 unit thermal discharge of MNPS- (NUSCO al.1990), a framework of baseline studies exists to 1988b). At each station, ten replicate samples aid in evaluating impacts of human activities on (0.0079 m2 cach) were collected by SCUBA divers marine benthic systems, using a hand held coring device 10 cm in diameter Benthic Infauna 83 l i
- y North 1km
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0: f mi Niontic Scy WNP3 INS , JCS , pg EFS Block k
.O poini GNS Fig.1. Map of the Millstone Point area showing the kcation of subtidal infaunal stations (EF= Emuent. GN= Giants Neck. IN= intake.
JC= Jordan Cove). x 5 cm deep. Each sample was placed in a 0.333 Data Analyses mm mesh Nitex bag and was brought to the surface. When taken to the laboratory, samples This report summarizes results of the were fixed with a 10'7c buffered formalin / Rose macrofaunal sampling program ' conducted from Bengal solution and after a minimum of 48 h, September 1979 _ to June 1993. The period organisms were floated from the sediments onto a extending from September 1979 through June 1985 0.5 mm mesh sieve and preserved in 70% ethyl is considered the 2-unit operational period while alcohol. Samples were examined using dissecting September 1985 through June 1993 is referred to microscopes (10x) and organisms were sorted into as the 3. unit period. A sampling year encompasses major groups (annelids, arthropods, molluscs, and quarterly collections made from September others) 'for later identification to the lowest through June of the' following calendar year. practical taxon and counted. Oligochaetes and rhynchocoels were each treated in aggregate Sedjments because of the difficulties associated with identifying these organisms. Organisms that were Sediment sieve fraction weights were used to too small to be qucatitatively sampled by our methods (e.g., nematodes, ost racods, copepods, and construct cumulative curves for 2-unit (1980-85)'. and 3 unit (1986-93) operational periods bv igraminifera) were not sorted. Grain size and the ' pooling quarterly weights from each sieve used for silt / clay fraction were determined from a 3.5 cm crain size analysis,in each 2 unit operational year diameter x 5 cm core, taken at the time of infaunal I and each 3-unit operational year, with years serving sampling. Sediment samples were analyzed using as replicates. Shifts in sedimentary environments the dry sieving method described by Folk (1974). over the 2-unit and 3-unit operational periods were then quantitatively assessed using the Gompertz function. This function has a sigmoid shape and 84 Monitoring Studies,1993
can describe cumulative data (e.g., growth data) from the Northeast Utilities Environmental Data that are not necessarily symmetrical about the Acquisition Network (EDAN). Daily averages of midpoint of their range (Draper and Smith 1981). 15-minute values were calculated for the period This feature provides the flexibility. to fit June 1976 to June 1993. cumulative data with or without an inflection point Wind Speed and Direction - Wind speed and (s-shaped versus parabolic) within the direction (at the 33 foot level of the Millstone ' observational range. The form of the Gompertz meteorological tower) were extracted from the function used was: EDAN database for each 15-min interval from June 1976 to June 1993. These values were used C, - 100 exp[-ch] to calculate a wind index, which was the wind speed weighted by wind direction. A navigational where Cycumulative sediment weight at point 1, chart of the sampling area was used to calculate p= location ofinflection point in units of grain size site-specific wind directional weighting coefficients. and x= the shape parameter (Gendron 1989). The directional weight ranged from 0, when wind ' could not influence the station, to a maximum of This function was fitted to data separately for 1, when wind-induced waves could directly affect , 2 unit and 3-unit operational periods using the area. The wind index was then computed by non-linear regression methods (SAS 1985). multiplying the directional weight by the wind Two-sample t tests were used to test for differences speed. Because the effcci of wind was assumed to between the x parameters of curves based on data be cumulative, daily averages were derived using collected during the 2-unit and the 3. unit only wind index values greater than 0 (that is,- operational periods. when the winJ was from a direction which could produce wind effects). Multiple Regression Analyses Climatic Extremes (Destations) - Additional explanatory variables were created to represent Multiple regression techniques were used to unusual climatic conditions which occurred during minimize the unexplained temporal variation in the sampling period. High or low deviations (i.e., community abundance, in number of species and in extrernes) were derived for wind, rain, water and the abundance of numerically dominant taxa. air &nperature data and calculated as the Several explanatory variables (described below) difference between the quarterly mean or daily were used to remove variation that was attributable value and the 16-year mean (1977 93) for that L to fluctuations in sediments, reproductive or - quarter. Deviations based on quarterly means recruitment cycles, or climatic conditions. This reflect the effects oflonger term extremes (e.g., an technique was used to improve the sensitivity of unusually cold winter), while those based on daily analyses later performed to identify and compare values tend to remove the effects of shorter term long-term trends in data from the 2 unit and 3-unit episodic events (e.g., storms). Daily deviations sampling periods. Analyses were based on average were averaged and also summed in each sampling quarterly abundance data after In(x + 1) quarter to assens cumulative effects. transformation and on species number collected Sedimentary Parameters Sediment mean grain from September 1979 through June 1993. size and silt / clay content were obtained as part of Explanatory variables used in the regression the monitoring studies and these quarterly values analyses were as follows- were used directly as explanatory variables in the Freelpitation - Daily precipitation records multiple regression models. ; compiled by the U.S. Weather Bureau at the Iteproductive - Itecruitment Comp (ment - Groton Filtration Plant, Groton, CTwere obtained Infaunal organisms in the Millstone area exhibit , from June 1976 through June 1993. Values to the annual peaks in abundance, often reflecting the nearest 0.01 inch were used as Prain" data. seasonal nature of reproduction and recruitment j Water and Air Temperatures -' Ambient water cycles or periods of favorable climatic conditions. temperatutes (at the intake structures) and air Spectral analyses of quarterly data showed annual I temperatures (recorded at the 33 foot level of the cycles in community abundance and number of i ' Millstone meteorological tower) ec obtained species. To account for this periodicity, harmonic Benthic infauna 85 i I
terms (Imrda and Salla 1986) having a period of 1 taxa collected at each station were used - to year were also included as explanatory variables in construct ' cumulative abundance curus . (k-the regression models. dominance curves) for 2 unit and 3-unit In all,32 variables were initially used during operational periods. Comparison of k-dorainance , model selection steps. These variables included curves has been suggested as a means of assessmg ! two sedimentary parameters. Iwo shifts in the structure of macrofaunal communities seasonal / reproductive components and seven (Warwick 1986; Warwick et al.1987). Curves were climatic variables, each of which had four values constructed by plotting percentages of cumulative representing daily and quarterly high and low abundance (ordinate) versus the natural logarithm extremes. of a taxon's rank (abscissa). To assess possible shifts in infaunal community structure between 2-Response Modeling and Trend Analysis unit and 3-unit operational periods, the same ; Gonvertz function used for sedimem data analysis Quarterly abundance and species number data was f tied to cumulative abundance data : by from September 1979 to June 1985 (2 unit period) substituting species abundance for sediment weight, and September 1985 to June 1992 (3-unit period) and species rank for particle size in the equation. were separately detrended using a linear regression Two-sample t-tests were used Ia compare model. A step-wise multiple regression was then parameters of curves representing data colle led applied to the residuals of quarterly data (i.e., the during the 2-unit and 3 unit operational periods. variability or " noise" about the linear trend) over the entire sampling period to identify explanatory Results factors . and combinations of factors whose regression coefficients were significantly different Sedimentary Envhonment - from zero (ps0.05). This probability lesci was chosen to guard against fitting more parameters Sediments at subtidal sampling stations in the than could be reliably estimated,' given the sample vicinity of Millstone during 1993 were comprised size. The model that minimized the of fine to coarse sands. The finest sediments were mean-square-crror and maximized the R3 was found at IN.where quarterly grain site means were selected to " clean" the original data, and produce 0.18 to 0.30 mm (Fig. 2). Sediments were most a ilme-series free from variation attributable to coarse at EF; the quarterly grain size range was concomitant physical factors or known biotic 0.50-0.62 mm, Intermediate sizes were observed at - ; processes such as reproductive / recruitment cycles. ' JC and GN (ranges of 0.210.25 mm and 0.29-0.50 Linear models were then refitted to the variance- mm, respectively). Quarterly silt clay contents , reduced time-series corresponding to the 2-unit werc highest ut JC (18.7-22.5G ), lowest at EF (1.3- , and 3-unit periods. The nonparametric (l.c., 3.8'?c) and intermediate at GN and IN (12.1 13#4 C distribution free) Mann Kendall test (Hollander and .t710.lG, respectively). Sediment grain st/c and Wolfe 1973) was next used to determine and silt clay contents observed during 1993 were whether these 2-unit and 3 unit series exhibited within the ranges of these two sediment ; significant trends and Sen's nonparametric parameters during both 2 unit and 3. unit J cstimator of the slope (Sen 1968) was used to test operational periods. ' for trend differences. These two tests were Cumulative curves based on sediment sieve suggested by Gilbert (1989) as particularly well fraction weights (Fig. 3) were used to characterize suited for analyzing environmental monitoring data subtidal environments. and allowed us to .i because no distributional assumptions are required. statistically compare sediments collected at each I and because relatively short time series (n < 10) are station during 1993 to those collected over 2 unit l acceptable. In this report, plots of the origina'l (1979 85)and 3 unit (1986-93)operationalperiods. ; quanctly data, adjusted data and a gr phical Dased on t tests of Gompertz parameters derived representation of the linear trend are provided for from these curves, significant differences between community abundance, numbers of species and fot 2-unit and 3 unit periods were noted only at EF :J selected taxa. and JC. Differences between 2 unit and 1993 Abundances of the top ten numerically dominant sediments were also significant at both stations.
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, ~ . - - - . _ m -
TAitLE 1. Annual mean number of species (S). number of indwiduals (N) of each major taxon collected in 1993. Jurmg 2-unit (1960-1985) and 3 unit (19861993) operational yean at Mdistone subtidal stations. 1993 2-Unit Period (1980-1985) 3.Umi Period (19861993) (S) (N) MEAN CV' 'MEAN CV MEAN CV MEAN CV (5) (N) (S). (N) Effluent Potychaeta 60 2433 67 2.7 4675 17.7 62 2.8 - 2579 12 2 Oligochaeta - 2703 - - 2885 13.9 - - 4289 1131
+
Mollusca 23 214 29 4.8 497 29.3 27 4.1 472 19J Arthropda 25 418 39 4.5 723 21.9 30 5.2 416 9.5 Rhynchococia - 532 - - 138 23.2 182 28h -
'Ot hen' 5 51 4 20 4 11 48 7 4 8.5 146 3f. 7 Total 113 6351 139 8930 123 8084 Giants Neck Polychaeta 63 9256 67 4.4 6683 12.9 60 5.1 7128- 8.5 Oligochaeta - 2717 - 1932 126 2253 5.4 Mollusca 29 416 20 9.9 260 20.7 26 5.8 282 9.9 -
Arthropoda 29 1670 35 46 624 5.8 32 8.6 1052 21.6
' Rhynctweela -
172- - 62 20.4 - 74 20.1 '-
'Ot hers' 3 46 3 26.4 8 43.2 3 12 4 17 28.9
- Total 124 14277 125 9569 121 19800 ;
Intate Polychaeta 63 5070 43 3.3 1110 9.3 52 3.9 3000 21 8 Ohgochaeta - 700 253 16.2 . . 397 23.5 Mollusca 22 303 18 10.8 199 27.0 20 46 503 13.8 Arthrop4a 32 858 25 . 8.2 829 47.4 27 5.0 1710 53.1 Rhynchococia 4 39 - 15 26 4 - 25 19.8
'Othen' 1 1 1 68.3 1 74.2 1 33.3 2 35 4 Total 118 6977 87 2405 100 5637 l-Jordan Ome Polychaeta 72 10153 64 4.7 6513 23 2 63 2.7 7887 13 2 Obgochaeta 2070 - .
4124 24.2 - - 2700 7.3 l Mollusca 25 708 24 12.8 446 24.6 28 3.5 717 80 + Arthropula 26 1608 27 6.2 641 55.4 27 60 964 35.1 Rhynchocoela - 172 79 12.3 '13.8 l- - 91 L 'Others' 3 7 3 33 1 4 28.1 4 7.3 12 33.3 j- Total 126. 14718 118 12110 122 12377 l l' !.
- CN. of the mean estimate = (Standard Error /Mean) x 100 l
88 Monitoring Studies,1993
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1 Sediments at IN in 1993 were significantly different (nearly 50% of total individuals). Mollusc and l (coarser) from those collected during both 3-unit arthropod species were not as abundant as .; and 2-unit periods. The shift at EF reflected the polychaetes; ranges of numbers of species were 22 j declining silt / clay fraction and the increasing grain 29 and 25-32, respectively. Numbers of molluscs size since Unit 3 began operation' (Fig. 2). and arthropods were generally similar between the -l Conversely, silt / clay content increased and average operating periods. At EF during 3-unit operation, , grain size decreased over the same time period at including 1993, oligochaetes were dominant. At . J C, GN and J C, oligochaetes were second in i abundance (after polychaetes) followed by ' General Community Composition arthropods and molluscs. Arthropods ranked second in abundance at IN, followed by Mean numbers of species and of individuals in oligochaetes and molluss. Rhynchocoels and major invertebrate groups collected during 1993, "Others" contributed little to total abundance and during 2-unit and 3-unit operating periods are during either operational period. , presented in Table 1. The annual mean numbers Some notable differences in general community of species at subGdal stations in 1993 ranged from composition between operational periods are 113 (EF) to 126 (JC). The 1993 mean at EF was evident, based on species number. During the 3 lower than the means for 2-unit and 3. unit periods unit period, the polychaete dominated community (139 and 123, respectively); during both at EF present during the 2-unit operation was operational periods, mean number of species had replaced by one dominated by oligochaetes. been highest at EF in relation to operational Abundances of polychactes and oligochaetes were ; means at other stations, in amtrast, the 1993 similar during 1993. Also, the number of means at IN (118) and JC (126) were higher than arthropod species at EF was lower during 3-unit 2-unit (87 and 118, respectively) and 3-unit (100 operation than during the 2 unit period. The , and 121, respectively) operational means. Number opposhe trend was observed at JC; i.e., more of species at GN during 1993 (124) was lower than polychaetes and arthropods, and fewer oligochaetes the 2-unit mean (125), but higher than the 3-unit were collected, on average, in the 3-unit period mean (121). than in the 2 unit period. At IN during 3 unit Similar to spatial trends in number of species, operation numbers in all taxonomic groups the largest number of individual organisms was increased. At GN, there was little change in : collected at JC (14,718), and the smal'est at EF numbers between operational periods. (6.351) in 1993. Means were also highest at JC over both 2-unit (12,110) and 3-unu periods Community Abundance (12.376); low 2 unit and 3-unit means were both recorded at lN (2,405 and 5,635, respectively). The Ranges of average quarterly abundance (per 1993 mean number of organisms at IN was higher core) at subtidal stations during 1993 were 134-194 (6,977) than the two operational period means. at EF,279-408 at GN,119 314 at IN, and 292 369 The number of individuals collected at GN in J993 at JC (Fig. 4). At cach station,1993 densities were (14,277) was also higher than the means of 9569 within the range, for their respective 14-year time and 10,806 for 2 unit and 3. unit periods series. In general. infaunal abundance at all-respectively. Fewer individuk were collected at stations during the 3-unit period (1986-1993) was EF in 1993 than over the two operational periods similar to that observed during ' the 2-unit (2 unit mean: 8,930,3-unit mean: 8,084). operational years. Overall, seasonal and annual Polychaetes were the dominant group in terms fluctuations were lowest at EF artl highest at IN: of numbers of species at all stations during 1993, however, no consistent seasonal periodicity was
- ranging from 60-72 species. Polychaetes were also evident in community abundance at any' station the most abundant taxon in the 2-unit and 3 unit during the 14 year period. Analyses of long-term operating periods (ranges 43-67 and 52 63, trends .in community abundance indicated a ,
respectively). Except at EF during the 3 unit significant (p>0.01) increasing trend at EF during period and during 1993, polychactes also 2 unit operation, resulting primarily from peak i dominated in terms of numbers of individuals abundances recorded near the end of that period ' Benthic Infauna 89
, - , ~
l g Numbers of Species . i
, trrtutwf svewca f The mean number of species (per core) collected E , - during-1993 ranged from 21-28 at EF, 26-35 at
.g, 9 ,
"fc,:,, . ^ . GN,25-30 at IN, and 30-38 at JC (Fig. 5). These 5- means were within the range of annual means
- 9. observed at each station over the previous 14-year period, A significant increasing trend in quarterly species number was evident at EF and GN during . f h////////////// 2-unit operation, and coincided with high species- i richness evident at most stations during the period
- 1984-87. During the 3-unit operating period, there wS'e sumn were no significant trends in species richness evident at EF, GN, or JC. However, at IN, there
[
.c.u .
J. _ fJ was a significant increasing trend in quarterly'
,,,, j . ,.,. % - , .- .-_ ..v..** numbers of species _ evident over the 3-unit 7 ,
, operating period (stope=0.194).
- 9. I ,
Community Dominance -
f p p *e *s y *? r
*
- spp*s i *
- The dominant taxa . collected during _1993 at subtidal stations included the polychaete species ae _ Aricidea catherinae, Thanx spp., Prionospio !
f steenstrupi, Polycirrus crimms, Scoletema tenuis, f ~~ , Protodorvillea gaspeensis, Mediomasrus' ambiseta, ,
, f. Pygospio elegans, and- the arthropods Ampelisca l* g"Qy. . ,} ,..
5
,e , "2"~
vadorum, A. verrilli and Leptocheirus pinguis and tepresentatives of the class Oligochaeta (Table 2). 5- i- ' The top four ranked taxa at each station in 1993 i accounted for 50% or more of all individuals, and j j *+ *..* i~s* 1* *e, *i 's"-' +
.s were: Oligochaeta, Protodorvillea gaspeensis, Rhynchococla, Tharyr spp. at EF; 7haox spp., 2 Oligochaeta, Aricidea catherinae, Ampelisca
_~~ n ewt suerm vadorum at GN; Aricidea catherinae, Pygospio f elegans, Prionospio steenstrupi, Oligochaeta at 1N; . g~ , , . Aricidea catherinae, Oligochaeta. Leptocheirus i ' , ., , . ' %'q ,, ' , , , :
, pinguis, Polycirrus eximius at JC (Table 2). In most '
l- cases, these organisms have been the dominant , t - subtidal taxa in both 2. unit and 3 unit operational
** I periods. There was a large increase in relative l abundance of the polychaete Aricidea catherinae at '
jfjffj;jjjffjfj IN and JC in 1993, which accounted for 16.3% and 26.0% of the Individuals collected at these stations, l'ig. ( Quarterty abundance data (dots), and variance-reduced IUSEUUI5YUI Y' data (dashed line), and linear-trends for subsidal cornmuruties Increase in abundances of f)gospio elegans and
. tefore and after Unit 3 operation at MNPS. Prionospio steenstrupi were also noted at IN in 1993, and a decrease in abundance of oligochaetes (19M). During the 3 ur.it operating period, a was observed at JC. Tharyr spp relative signi0 cant increasing trend was detected only at abundance was higher at all sites in 1993, and JC.
particularly at GN, where this taxon accounted for 34.1% of individuals, compared to 13.89 and ., 90 Monitoring Studies,1993 t n w - , y---
. Relative abundances of dominant taxa between :j
(""* 5 ** operational periods have exhibited considerable j consistency, with a few exceptions. For example. { E- .. oligochactes continued to be the most common i E, ; . . )d :. ,; ,, taxon overall during 3-unit operation (accounting i {* g.'h'.-
, .v
. . . *([*(. ' ' . Y' , 0 $.
for 8.0 to 52.8% of individuals), as they .wcre during 2-unit operation (10.3 to 40.8%); however.
- as discussed in the previous section, oligochaetes -
, were more abundant at EF and less abundant at
/////////////// JC during 3-unit operation. Most stations were .
characterized by one or more clearly dominant
. taxon (oligochaetes at EF, GN and JC, Ariciden
"'$ ""d
- catherinne at GN and JC and Tharp spp. at GN)
!" during both operational periods. There has been E- no single dominant taxon at IN during cither E . . ' c. k , . '-
operational period, where mean relative f ,,, Oy.-,U j i D ' *
,d,! abundances of any single taxon collected there y ,
j rarely exceeded 10%. 1 i Dominant Taxa f f p f f f f f f f f, ;; Eight subtidal taxa have been identified as being affected or potentially affected by construction and ' operation of MNPS. Trends in the abundance of , y these taxa were examined using the same g- ! , techniques as those applied to overall community
- 5. i i abundance and numbers of species. For a review 5
- i i . . -
of the general ecology of these dominant taxa, refer to NUSCO (1992).
!". ;%. .3 Ds
,. *.'_ M * '.. . ',.
l _ J Oligochaetes - Oligochaetes were ranked first in
////////////// overall abundance during both 2-unit and 3. unit ,
operating periods, accounting for 10 41% and 8-
' q 53% of total individuals, respectively (Table 2).
During 1993, oligochaetc . abundances were
; j generally highest at GN (35-92/ core) and EF (45
[- g.
, , . .. g,'
,l 75/ core), lowest at IN (14 21/ core) and intermediate at JC (33 65/ core) These densities j ,, 4._/ -ry -
1::...'.' . were within the ranges of densities in previous t ,b .. - study years. Analyses of trends in oligochacte abundances 1 I revealed an increase at EF, and a decline ai GN -
/ / //////////'/ during 2. unit operation (Fig. 6a and b).L . Trend -
analvsis for the 3-unit period indicated a significant l'ig. $. Quanerfy numtier of spenes data (dots), and vanance-inC ase in oligoChacte abundance at IN (Fig. 6c). reduced data (dashed kne) and linear 4 rends for suNidal I communities t,efore and after Unii 3 operation at MNPS. At EF, GN and JC, oligochaete abundance has ; remained at similar level _s during the :3 unit 1 18.5% over 2 unit and 3-unit years, respectively. operating period (Fig. 6a, b and d).- j The increase of Tharp spp. at GN was mirrored by . j a marked decrease in relative abundance of Aricidea catherinae A. catherinae was among the [
. Ariciden catherinne, dominant taxa al' all subtidal stations during 2-unit '1 Benthic infauna 91 i
l H j s a , e n -r ,
TAllt.E 2. Mean relative abundance" (%) and coefficient of variaNlity (C\$ of each of th- ten inost abundant taxa collected at the Millstone subtidal stations during 1993,2. Unit operational yean (1980-1985) and 3 Unit oprational yean (19861993). 1993 2-Unii Period (19801985) 3 Unit Period (19861993) MFAN. CV MEAN CV -
% % g- 1 Ernuent :
3
~l Oligochacta 42.6 32.9 44 52 8 1A -
Prosodonillea gaspecruis 8.9 4.6 13.3 8.0 ' 4.0 '\ , Rhynchococia - 8.4 2.4 12.2 3.0 15.9 Tharp spp. 4.8 2.6 28.1 30 18.2 2 Polgima cumiar 3.2 10.8 10.2 3.3 . 23.7 Aricidca cadurinae 30 4.1 20 6 16 31.4 Ampharete americana 1.9 . l .6 24.1 . Scolczema tenuis 1.9 l9 14.5 Ampelbca radorum 1.7 13 30.8 Cbmencita mucosa 1.6 1.5 32.5 Parapionosyllis lungicirrota 1.b i 8.8 2L i 4.5 i flaliplanella luciae } .3 70.7 2.2 20.8 1 Pagurus acadianus - . - 20 13.4 Prionospio sternstrupi . - 1.9 32.6 I Spitphanes bombp - t .6 28.4 Harmothoc imbricata . . l .4 86 8 Eumida sanguinea .
. l .3 24.5 1
Giants Nect i Thorp spp. 34 1' 13.8 39 18 5 4.8 Ohgochaeta 19 0 20.8 39 22.1 2.2
~
Aricidea catherinac 7.4 19.6 $0 15.3 $1 Ampelisco radorum 48 1.2 18,5 2.7 24.0 Empone dispar 3.5 2.7 19 6 31 7.1 huonospio sicenstrupi 3.0 20 16.1 40 27.9 Ampharete americana 1.9 I .$ 20.1 Scolcremo senus 1.9 3.1 14.1 36 69 Polydora quadnlobain 1.5 18 26.8 Msaella lunata 1.4 . 14 30 8 Capitella spp. 1.x 19 4 1.8 10.7 Trilma agila f .5 25.8 l .5 38.4 Pagurus acadaanus 1.3 34.3 1.6 21.1 Medwmastus ambbeta , 4.8 27.5 4.3 2$.9 ' Phonocephalus halbolli 2.7 13.0 2.0 13.5
- Ilased on log-transfortned data i
" C.V. of the mean estimate = (Standard E.rror/Mean) X (1(K))
- = Not among the dominant taxa
)
i 92 Monitoring Studies.1993 '
. TABLE'2. continued.
-1993 '2-Unit Period (19801985) 3-Unit Period (1986-1993)
MEAN CV MEAN CV
% % W Intake Aricidea cadnerinae 163 6.7 22.4 6.0 173 P)pspio elegans 12.4 - 34 - 28.6 Prionospio stenstrupi 10.5 2.2 35.8 43 ' 29.1 ~r Oligochaeta 10.1 10.3 11.1 8.0 - 10.9 '
TharyTspp. 9.7 - 43 13.4 Erogone hebes 6.8 3.6 29.1 5.2 20,9 Ampelkca nudorum 5.0 - 3.1 22.4 Ampelisca wirilli 2.5 5.1 31.1 3.2 20.5 L* Protodarvillea gaspeensis 2.4 2.6 ^ 22.1 Spiophanes bomb), 2.0 - 2.5 30.s 2.2 16.6 Capitella spp. 30 253 4.2 21.4 Sabellaria vulgaris J3 60.2 Nucula prodma 29 2st2 43 20.s-Mediomasnes ambiseta . - 4.0 27.2 Lqnocheiru.s pinguk - 3.0 39.2 Ampelbca abdaa - 3.0 - 53 0 ' Tellina agilis - 3.9 193 3.9 17.9 Maldanidae - - . 1.5 193 Onenia fusiformis . 2.5 ' [ 26.3 . Gammarus lamncianus 2.2 40.0 l .5 $4.9 : Jordan Ctwe P Aricidea catherinac 26.0 14.6 s. ) 15.9 83 ;; Oligochaeta 14.1 40.8 39 23 0 - 4.0 ; Leptocherruspinguis 93 1.5 34.5 3.9 30.6 , Polvcirrus cdmius 1.8 4.3 14.2 5.0 12.4 Thor)x spp. . 5.2 3.1 133 4.1 5.0 Pisonospio strenstrupi 4.7 1.4 24.8 5.0 .18.6 Scoletema tenuis 4.6 4.7 13 1 5.9 ' 63 Mediomastus ambuesa 3.9 7.2 26 3 83 16.8~ Polwlora quadrilobata 1.5 - - 1.5 38.2 ' Spiophanes bomlyr 1.5 1.4 37.4 ~
^
Nucula prarima . 13 )35 2.s 173 . ;i Capitella spp. - 2.2 17.9 23 '17.2 Tellina ergr/is - 2.2 23.6 1.9 14.9 Microphanalmus aberrans - 1.5 22.6 2.9 ' . )8.6 Cossura longocirrata - - - l .5 26.1 ;
.s I
.]
Di
. . i Benthic Infauna ' 93 . ;
.. i
sW i trrwt.n sa,x e trrwc.o sew j_
.t i l -
o .. . g . .. is,~ , , ,
. L r r_ r_ ,
N ' e yy. . , . .. %.~ ,y.
.,- g .-
- 3. ;. . .
5, w :. ,
- .w'wx I
j m o '. M F. l
'?
/// / / / .* - ^/////// ///////////// // ,
_ ces uta se a e) cuesutc 52swx n .; l y-
.-... g E
E s e ; i s p- p .. a
. . I 8
g a
%.gA Sl rir I f ..",,. ,'. M s
J
; y , ', N ; ..
3 ; x.,
.'A.*.*.g i
. I i ,e ;
+e .s e .,.. .e .e .e ., r i . e ., e .e .,a
..~~ ...<._
+ . . ,
_# <.,,i+ _ es t sveta el j j. g ow .. _ g l' wt swa mw,. .. .a,.m, E
- ,E l. .
9- E 8 E r I- 4 7.. .. i . j l
. . pi
.v.c.A" '
S gm.' . 3
. ... pt.
iA .
, ,1 * .
4 t .,e p 4 p 5 .x .< .s . .s c . ,,e. . - a
. e .i .i . s.
.e .e c i .a .p .e s a
.e ..;
g acou ccut saw o% a.,i. a3 _ l xe-.... tc..esw x r ( } E ! E c ' l e, . , . - ,, , , ' 4 s.,--
, a. . .
x< -y. -1 9 ' _ _ , g . ... . .. g_ , I
; ,l we.=yf+ 7+c:,.
- 1 -
' i
. i .1 i. ,
////'//////////! .
!!/ff////!!////
Hg. 6. Quarterty abundance data (dots), and variance. reduced Fig 6. contmued. data (dashed line), and lancar. trends for selected dommant organisms comprising Millstone subiidal communities before at EF,19-31/ core at IN,20-34/ core at GN, and 84-and after Unit 3 operation at MNPS. ] 103 at JC. 'i operation, and at rnost subtidal stations, except EF, The averag quarterly abundance of Aricidea during the 3-unit operating period (Table 2). The catherinne exhibited several trends over both 2-unit range in average density during 1993 was 4-7/ core and 3-t'ait operating periods (Fig. 6eh). Relationship; among operational period trends at 94 Monitoring Studies,1993 L! l 1 i l
'l
. ~ . . . , - - . - - - .. - - - , ..
,,,, throughout our studies with no apparent trend in
_ uw suem 4 cither operational period. g- ru, w. v. [, Tharyx spp. . Thanx sppc were among the j -,,, ' dominant taxa at most subtidal stations during 2-s ' j unit and 3-unit operating periods. During 1993,
} ,, l densities of Thanx exhibited high variability among a '
, g subtidal stations, ranging from 13/ core at EF,69-
, g;- l. P ',- dy si r 171/ core at GN,3-26/ core at IN and 15-18/ core at
/////////////// JC (Fig. 61-l). ~ At the GN reference station, Thanx spp. densities were consistently high, ranking third,
,,,,, second and first in the 2 unit, 3 unit operating.
**" " "5*
- O ru, n periods and 1993, respectively (Table 2). At EF
, , , and JC, Thanx spp. ranking was also consistent, E but at a lower level over the entire study period,
[. , ,,,- ranking fifth during both operating periods and
$ U C*i.rA ^* '< %*" ~ ,
fourth in 1993 at EF, and sixth during both periods y ,, V M and fifth in 1993 at JC. Thanx spp. were among I the numerical dominants at IN only during the 3-
, unit operating period, ranking fifth in abundance
/// /////////4 // in 1993, and fourth for the overall 3 unit period.
This taxon was virtually absent from that site during the 2-unit period. { [,57 i i Results of trend analysis on Thanx spp.
; ,,,, j abundance during 2 unit operation indicate a : "
E i significant increasing trend at EF, GN and JC,
$ ,,, .; i Trend analysis of 3 unit operating data indicated a j '
continued significant increase in the abundance of i ., ' ~
.j Thanx spp. at JC and the reference station GN.
- g. g,,, g' '7* ,
During the same period . there were no trends .
. g % ,, % ,, f evident at IN, despite increases in recent years, or -
/// / / / / / l / / / /-f / at EF. l
, Polycirrus eximius During 1993 P. crimius was >
_ [ m'uu.o " wmj o' among the dominant taxa at JC and EF, ranking. ; f,,,, ! ! fourth and fifth (Table 2), and averaging 12 72/ core E ! and 212/ core, respectively (Fig. 6m.n). . Trend j, t j analysis indicated significant increasing densities at E both stations during both operational periods.
}~ cs l. However, the 1993 March and June abundances at g'k M 9Y'FY'-
EF were among the logest' values reported for the l" 3 unit operating period.: In contrast, JC densities .
/// //////////// were within the range of values reported for the 3-unit period, with the September value among the Th 6. mnunued. highest reported during both 2-unit and 3. unit EF and IN were similar; at both sites, abundance operating periods. Historically, P. eximius has -
exhibited both seasonal periodicity and regional of A. catherinae significantly declined during 2-unit long-term cycles at all stations except IN (NUSCO - operation, and significantly increased after Unit 3 3993), start up. Abundance of A. ~ catherinne also increased at JC during 3 unit operation. 1
- Abundances have been consistently high at GN Benthic Infauna 95 4
i - 1 9 1
==
grrturm sveth 'I-rn) , cw m %C ,$se' x 0I n% .,. , ( . s i, u . !
.E- ?- .
t g-I 1 9- *
.;4 9 .- i i d * ' ,
- 5 I l b I.4*,' h#5 )s.*.
e :
- g. i, n ,*'.
V ' ;-4^4pe.
,'.s 7 grG A '
%Af l y
- l
, *
- L.yf * * ;* ,
a
/////////////// ///////////////
o e c u sue m o _ me m s;e a ! s, i _g-. u~ . , g 3.~. !
, g >
E E l l c :
$* - $ '*l a, .. .. .,
e, -
'YT. i h.. ;- S . Q, ;., .
' "l .wf. N.b '
fff f f f ,Y fjff;;j ., Q^f,,*lffjff ; ( " Fig. 6, continued-
,_l a n w. w m :
Scoktema tenuis - S. tenuis was a dominant i! *">""""""""* component of infaunal communities during the 2- j' , unit and 3-unit operating period at JC (ranking ( , fourth and third, respectively) and GN (ranking f. , [* ' *. , ,. fifth for both periods; Table 2). Average densities [! l "
~ ' ,)
during 1993 were 3-12/ core and 8-33/ core at GN ' l y, - and JC, respectively (Fig 60-p). These densities ...' ,
,,T ,
~%
were within the range of density values from
# ~"~^
,y previous years. At both GN and JC, an increasing trend was observed during 2-unit operation, likely - - - ~
due to low abundances of S. tenuis at the beginning _ .~. .i w - , of the time series at both sites. Low abundances I ***"~'~""*i in 1993 resulted in a~ significant decreasing trend j ' for the 3. unit period at GN that had not been i . ., i apparent in previous years (e.g., NUSCO 1992, [~{, * -
']- C,[ ~, 4j(N ".1,l 1993). Abundance' at JC have been more ! !, .__ j " .
consistent during 3. unit operation, with no ; ., ' I significant trend detected over that period. i ,
.i a .. , 77
~ , ' '
~
n. s s '. Mediomastus ambheta M ambiseta abundances continued to decline in 1993 relative to the period 1984-87, when an area-wide pulse in abundance Fig. 6, conimued. was reported (NUSCO 1984). The density range at the GN reference station during 1993 was 2-4/ core, and at JC,M ambiseta density ranged from less enreme, pulse / decline cycle was also noted at EF and IN. where, in 1993, M ambiseta was not 8-22/ core (Fig. 6q-r). Trend analysis of 3-unit operating data indicated significant decreasing am ng the dommant taxa. J densities at both GN and JC. A similar, although
% Monitoring Studies,1993
. Protodorvillea 1,aspeensis - P. gaspeensis was ,
among the dominant subtidal organisms at EF g 7",',[,'; I "; ranking third and second in the 2 unit and 3-unit g. ; l operating periods, respectively (Table 2). During E , 1993, P. gaspeensis ranked second in abundance; j, quarterly values of P. gaspcensis were within the y , range of previously reported values, averaging 8- 9 ., j
'16/ core (Fig. 6s). Significant increasing trends /
l occurred at EF during both 2-unit and 3-unit , ag.[., , Ip,,g.-Q"~'7 f - - -
'l operating periods. The increasing trend during the ///////////////
2-unit period was attributed to low values in 1980. The 3-unit trend resulted from continued steady increases in the abundance of this species following Unit 3 start up. y g, ((* ") l l E , p c j i 1 9 [ ruww ww_ . . . , . _ ' rj , . y ,, _. %---Wr.m.m-~ ~ E I i y e.. '
-m. j p '
G ,, l jf;,;;ff;fff; ef , a h ,,
- p. -mp , a , ., 'y' A :j.g y
-e v .- -
fig.6.conunued. presented in Fig. 7. At EF and JC, the location
't/fffffffffffff parameter (i.e., percent contribution of the top ranked organism) was significantly different between the two operating periods, ' reflecting Fig. 6. conunued. changes in the overall contribution. of the dominant Oxon (ie., olipochaeles), Additionally, Nucula prodma This small bivalve ranked only changes in the abundances of other taxa from the seventh at IN during 2-unit operation, but was the 2-unit to 3 unit operational period caused the fourth (tie) most dominant taxon during 3 unit overall shapes of these curves to significantly differ operation (Table 2). N. prorima was not among between the two periods. There was no significant the top ten dominants at IN during 1993; quarterly difference in the shape parameter between the 2-density values tanged from l-2/cate (Fig. 61). This unit and 3-unit periods at GN or IN. This species was the tenth mosA dominant taxon during similarity reflects the consistent contribution of 3-unit operation at JC, but was not among oligochaetes, Aricidca catherinac and Tharyr spp. at dominant taxa during 2 unit operation or during GN. and of oligochaetes. A. catherinac and 1993. Quarterly densities for 1993 at JC were l- Ampelisca rcerilli at IN. The lower position of the 11/ core (Fig. 6u). No significant trends were 3-unit curve at JC reflects a shift toward increased observed at either IN or JC during 2 unit equitability in the taxonomic distribution. In operation. During 3 unit operation, N. proxima contrast, the high starting point of the 3-unit EF exhibited a decreasing trend at IN, and conversely, curve indicates the numerical dominance of the top an increasing trend at JC. ranked taxon, oligochaetes, during that period.
The low starting point of the IN curves in both Cumulative Abundance Curves operating periods indicate that no single taxon was overwhelmingly dominant in either period (see Cumulative abundance curves representing Table 2b subtidal communities at each station sampled over the 2-unit and 3 unit operational periods are Benthic Infauna 97
Discussion Effective long-term monitoring of benthic g- infaunal communities ~is strengthened by r y ' ~,/ ~-'- identification-'of structuring mechanisms which ' y" produce characteristic fluctuations' in species
/
-d l crrwar suercat i no-85-su composition, abundance and dominance. However, -
even the first step in this process;i.e., separation i nswo"** of -naturally induced . physical and biological '
, mechanisms, including naturally varying levels of ,
utund wc or sac >cs s ~,. s mortality, recruitment, competition and vagaries in local physico-chemical conditions is often difficult g '" (Watling 1975; Flint and Younk 1983; Nichols , g - 1985; Watzin 1986; Rees and Eleftheriou 1989). g c' j' An attempt . has been made here (through y modelling and regression analysis) to account for. [ ,,, many of the important natural factors reported to 6 < effect differences observed in local benthic l j' o.w w s tnt'. communities, and thereby isolate other. factors 0 $[$Z1, possibly related to construction and operation of MNPS. Also, the establishment of two control - strategies, f.c., temporal (sampling a potentially
' u v i ccarsAats m / impacted site prior to impacts) and spatial (a site
, well beyond any power plant influence), has further --
g, g F[' improved our ability to separate natural factors from those related to MNPS. These methods of
- 3 impact assessment, integrated into a single study ,
[y. design, have allowed us to document community changes that were independent of power plant operations, as well as those directly attributed to f [ QQ,,"y the construction and operation of 51illstone Unit
/ t ae- a-cm.o 3.
Several significant area wide shifts in species o, , , , , 4 abundance and community structure have been - wr **uoc cr suas 5* observed over the course of these studies, and have been described in. detail in previous reports as 5.. M" ' unrelated to MNPS operation (e.g., NUSCO 1987, ' E ? 1993). These included large increases in 5 / abundance of the opportunistic polychaetc. f y =- l /,' aow., ove seem Mediomasms - ambiseta, and the . amphipods, Leptocheims pinguis and Ampelisca spp, which . occurred over several-years (1983-88; NUSCO dl / ' m -es-so.e
'"" "-D "
1989), as well as annual pulses in species abundance such as the substantial ' increase in i
, abundance of the spionid polychaete, PrionosproH e ,
a > mvauoc or snacs n4%,. steenstmpi, observed in 1992 (NUSCO 1993). i These increases could not be explam.ed by changes in site-specific sedimen:ary or regional climatic Fig. 7. Cumulatwe species abundance curves based on the ten factors (NUSCO 1989,1993): however because . most abundant organisms collected dunng the 2 unit (1980- these changes occurred at 'all stations, meluding 1985) and 3-unit (19861993) operational pend at MNPS. our GN reference station located beyond any. 4 98 Monitoring Studies,1993
effects of MNPS, their cause was assumed to be of A similar, relatively short term, disturbance natural origin and independent of power plant event resulted in sedimentary and infaunal changes construction or operation, at JC. In 1986,' silt was scoured from the area of Along with substantiating the area wide trends the Unit 3 discharge and settled at JC, increasing described above, GN showed long-term stability in silt / clay content of sediments in this area. These sedimentary characteristics and infaunal substratum changes resulted in decreased communities throughout the 14-yr Millstone study, abundances of the previously dominant taxa Sediments showed no significant changes over the oligochaetes and the polychaetes Polvcirms eximius - entire- study, either in terms of grain size or and Aricidea catherinae (NUSCO 198Sa). This silt / clay content, and patterns of total' infaunal depositional event likely occurred over a relatively abundance and community composition were, in short period of time (months), and its impac has general, consistent throughout the study. This evidently lessened since 1986. _ Despite the long-community was numerically dominated by the same term persistence of some of the deposited silt / clay-three taxa (oligochaetes, Thanx spp. and Aricidca at JC, reduced levels of silt / clay relative to those catherinae) in generally the same rank order and observed in 1987 have allowed some community :; relative abundance, during both 2-unit and 3-unit recovery. For example, the abundance in 1993 of # periods. oligochaetes, and the polychactes A. catherinae and
~
la contrast to the temporal consistency observed P. crimius abundances in 1993 were at levels at GN, all stations located near the power plant comparable to those observed during 2 unit years exhibited changes in both sedimentary character (Fig. 6d, h and m). These observations are and infaunal communities beyond those believed to consistent with those of other researchers studying ; reflect natural processes. Rather, these site- the effects of siltation on benthic ' infaunal specific changes are attributable to events communities (Rhoads and Young 1970; Jumars associated with either construction (at IN) or and Fauchald 1977; Turk and Risk 1981; Mauer et operations (at EF and JC) at Millstone (NUSCO al.1986; Emerson 1989; Brey 1991). , 1985, 1986, 1987). The impact of each of these in contrast to the short-term disturbance events events was most severe following initial detection, described above at IN.and JC, scour produced by and lessened in Osequent years, when a degree of the 3-unit discharge continues to affect both the recovery we obscred at each station. sediments and the infaunal community at EF. Impacts were noted earliest at IN, and were increased grain size and decreased silt / clay levels' associated with disturbances resulting from continued to be observed at EF during 1993. dredging and coffer dam removal during Unit 3 However,it appears that in recent years sediment, construction from 1983-85 (NUSCO 1987). Since community and species parameters have stabilized that time, sediments (primarily silt / clay content under the new environmental conditions created by levels) have stabilized and have become more the 3-unit discharge. Oligochacte abundance has similar to pre. impact years, and ongoing been remarkably consistent over the 3-unit period, community recovery is evident. In particular, although at a level considerably higher than during increases in the abundance of common species the 2-unit period -(Fig. 6a). Despite distinctly prior to 1983 (e.g., oligochaetes, Ancidea different sedimentary characteristics, this catherinne; Fig. 6c and g), with concomitant stabilization has allowed for the return of species decreases in abundance of Nucula proxima (Fig. 61) common during 2-unit operation, such as Aricidca and other opportunistic species (NUSCO 1993) catherinae and Po&cimis eximius (Fig. 6e and n). indicate that a recovery process has continued The community at EF should continue to develop through 1993. However, other species which have under 3-unit operating - conditions, but true established post irnpact populations,such as Thanx recovery of this community is not expected until spp. (Fig. 6k), maintained a degree of dominance power plant induced scour ceases. In 1993, which suggests that recovery at this site is . not complete. Changes such as these are typical of Conclusions those in marine benthic communities following disturbance (Kaplan et al.1974; Swartz et al.1980; Benthic infaunal studies continued io monitor Nichols 1985; Berge 1990). subtidal soft' bottom habitats in the vicinity _ of Benthic Infauna 99
-MNPS during 1993 for changes in sedimentary Diaz, R.J., and L.S Schaffner. 1990. .The i parameters -and faunal characteristics (total functional role of estuarine benthos. Pages 25 abundance, species number - and species 56 in Comrib.1595. College of William and composition). We have documented the effects of Mary, Virginia insi, of Mar. Sci. - both ; short-term episodic '(c.g., dredging and Draper,' N., and H. Smith. 198L Applied '
construction activities at'IN, and siltation at JC) . regression analysis. John Wiley and Sons, New , and long term continuous (effluent scour at EF) York. 709 pp. disturbance events, all attributed to MNPS Emerson, C.W, 1989 Wind stress limitation of 1 operation, along with subsequent community benthic secondary production in shallow, soft. recovery and/or development at all impacted sites sediment communities. Mar. Ecol.- Prog. Ser. throughout the period of 3-unit operation. 55:65 77. , Detection of these impacts was enhanced by Flint, R.W.1985. Umg. term estuarine variability 1 successful identification of area. wide community and associated biological response. Estuaries - changes (primarily fluctuations in species 8:159 169. abundance) attributed to natural factors, unrelated Flint,' R.W.,. and J.A. Younk. 1983. Estuarine to power plant operation. Distinction between benthos: long. term communny structure natural and power plant effects on the infaunal variations Corpus Christi Bay. Texas. Estuaries communities is on going and the primary objectise 6:126 141. of this program. Folk D. 1974. Pcuology of Sedimentary Rocks. llempshill Publishing Company, Austin, Texas.. , References Cited 182 pp. Franz. D.R. and J.T. Tanacredi 1992. Secondary Aller, R.C.1978. Experimental studics of changes production of the amphipod Ampchsca abdiin produced by deposit. feeders on pore water, Mills and its importance in the diet of juvenile , sediment, and overlying water chemistry. Am. J. winter flounder (P/curonectes americanux) in Sci. 278:11851234. Jamaica Bay, New York. Estuaries 15:193-203. > Berge, J.A.1990. Macrofaunal recolonization of Gaston, G.R., and J.C. Nasci. 1988. Trophie subtidal sediments. Experimental studies on structure of macrobenthic communitics in the defaunated sediment contaminated with crude Calcasieu Estuary, . Louisiana. Est uaries oil in two Norwegian fjords with unequal 11:201 211. cutrophication status, l. community responses. Gendron, L. 1989.- Seasonal growth of the kelp, Mar, Ecol. Prog. Scr. 66:103 115. Laminarin longicruris in Baie des Chaleurs. Bocsch, D.F, R.J. Diaz, and R.W, Virnstein.1976. Quebec, in relation to nutrient: and.hght Effects of tropical storm Agnes on soft. bottom availability. Bot. Mar. 32:345 354. macrobenthic communitics of the James and Gilbert, R.O. 1989. Statistical methods for , York estuaries ar.d the lower Chesapeake Bay, environmental pollution monitoring. Van. , Chesapeake Sci 17:246 259.- Nostrand Reinhold Company. New York. 320 Boesch, D.F.,and R. Rosenburg.1982. Response pp. to stress in marine benthic communities. Pages Goldhaber, M.D., R.C. Aller, J.K. Cochran, J.K. 179-200in G.W. Barrett and R. Rosenburg. eds. Rosenfield, C.S. . Martens, and R.A. Berner. Stress Effects on Natural Ecosystems. John 1977. Sulfate reduction, diffusion bioturbation Wiley, New York. Long Island Sound sedimentsf Report of the Drey, T. 1991. The relative significance of FOAM Group. Am. J. Sct. 277:193 237. biological and physical disturbance: an exampic Holland, A.F. 1935. Umg.tcrm . variation of from , intertidal and subtidal sandy bottom .macrobenthos in a meschaline . region of communities. Estuar. Coast. Shelf Sci. 33:339 Chesapeake Bay. Estuaries 8:93-113. , 360. Holland, A.F., A.T. Shaughnessy, and M.H. Hiegel. Commito, J.A., and M. Boncavage. 1989. 1987. Umg-term variation in meschaline : Suspension feeders and coexisting infauna: an Chesapeake Bay macrobenthos: Spatial and enhancement counterexampic. J. Exp. Mar. temporal patterns. Estuaries 10:227 245. Biol. Ecol. 125:33-42. Hollander, M., and D.A. Wolf. 1973. Non-100 Monitoring Studies,1993
l parametric statistical methods. John Wiley and 1985. Sons. New York. 503 pp. NUSCO. 1987. Benthic Infauna. - Pages 151 in 4 Horn, M.H., and R.N. Gibson. 1988. Intertidal Monitoring the marine environraent of Long- - fishes. Sci. Am. 256:64 70. Island Sound at Millstone Nuclear Power Jordan, R.A., and C.E. Sutton.1985. Oligohaline Station, Waterford; Connecticut. Summary of benthic invertebrate communities . at two studies prior to Unit 3 operation. Annual Chesapeake - Bay power plants. Estuaries Report 1986. 7:192-212. NUSCO.1988a. ' Benthic Infauna. Pages $9-117 in Jumars, P.A., and K. Fauchald. 1977. Monitoring the marine environment of Long Between-community contrasts in successful Island Sound at Millstone Nuclear Power polychaete feeding strategies. Pages 1-20 in Station, Waterford, Connecticut. Three-unit - B.C. Coull, ed. Ecology of Marine Benthos. operational studies 1986-1987. Univ. of South Carolina Press, Columbia, NUSCO.1988b. Hydrothermal Studies. Pages 323 S.C. 467 pp. 354 in Monitoring the marine environment of Kaplan, E.H., J.R. Welker, and M.G. Kraus.1974. long Island Sound at Millstone Nuclear Power , Some effects of dredging on populations of Station, Waterford. Connecticut. Three-unit ' macrobenthic organisms. Fish. Bull. 72:445-480.
~
operational studies 1986-1987. ! Kncib, R.T.1988. Testing for indirect effects of NUSCO.1989. Benthic Infauna. Pages 38 98 in predation in an intertidal soft-bottom Monitoring the marine environment of L(mg community. Ecology 69:1795-1805. Island Sound at Millstone Nuclear Power levinton, J.S., and S. Stewart. 1982. Marine succession: The effect of two deposit. feeding Station, Waterford, Connecticut. Annual Report j 1988. gastropod species on the population growth of NUSCO.1992.~ Benthic infauna. Pages 187-222 i Parannis litoralis Muller 1784 (Oligochaeta). J. in Monitoring the marine environment of Long Exp. Mar. Biol. Ecol. 59:231-241. Island Sound at Millstone Nuclear Power Imrda, E., and S.B. Saila. 1986. A statistical Station, Waterford, Connecticut. Annual Report [ technique for analysis of environmental data 1991, containing periodic variance components. Ecol. NUSCO.1993. Benthic Infauna. Pages 115-150 Model. 32:59-69, in Monitoring the marine environment of L(mg Maurer, D.,- R.T. Keck, J.C. Tinsman, W.A. ~ Island Sound at Millstone Nuclear Power Leathem, C. Wethe, C. Lord and T.M. Church. Station, Waterford. Connecticut. Annual Report , 1986. Vertical migration and mortality in 1992. marine benthos in dredged material: a synthesis. Rees, H.L and A. Eleftheriou. 1989. North Sea Int. Rev. ges. Hydrobiol. 71:49 63. benthos: A review of field investigations into the , Moeller, P., L Pihl, and R. Rosenberg. 1985. biological effects of man's activities. J. Cons, int. Benthic faunal energy flow and biological. Explor. Mer. 45:284-305. interaction in some shallow marine soft bottom Rcgnault. M., R. E;ucher-Rodoni, G. Boucher, habitats. Mar. Ecol. Prog. Ser. 27:109 121. and P.1.asserre. 1988. Effects of macrofauna Nichols. F.H. 1985. Abundance fluctuations - excretion and turbulence ~ on inorganic ' among benthic invertebrates in two Pacific nitrogenous exchanges at the water sediment estuaries. Estuaries 8:136-144. interface. Cah. Biol.-Mar. 29:427-444. . NUSCO, (Northeast Utilities Service Company). Rhoads. D.C., and D.K. Young.- 1970. The. Benthic Infauna. 1985. Pages 1-39 ' in influence of deposit. feeding ~ organisms on Monitoring the marine environment of Long sediment stability and ' community trophic Island Sound at Millstone Nuclear Power structure J. Mar. Res. 28:150-178. Station,Waterford, Connecticut. Annual Report Richards, S. W. 1963. The demersal , fish - 1984. . population of Long Island Sound. Bull. Bingham , NUSCO. 1986. Benthic Infauna. Pages 1-52 in Oceangr. Coll 8:1 101. Monitoring the marine environment of Long Sen, P.K. 1968. Estimates of ' regression Island Sound at Millstone Nuclear Power coefficients based on the Kendall's tau. J. Am. Station,Waterford, Connecticut. Annual Report l Stat. Assoc. 63:1379-1389. l I i l Benthic Infauna 101 1 I
Swartz, R.C., W.A.' DeBen, F.A. Cole, and L.C. Bentsen.1980. Recovery of the macrobenthos at a dredge site in Yaquina Bay, Oregon. Pages 391-408 in R.A. Baker, ed. Contaminants and Sediments, Vol. 2. Ann Arbor Science Publisher, Inc., Ann Arbor, Mich.' Thrush, S.F.,- R.D. Pridmore, and J.E. Hewitt. 1994. Impacts on soft. sediment macrofauna: the effects of spatial variation on temporal trends. Ecol. Appl. 4:31-41. Turk, T.R., and M.J. Risk. 1981. Effects of sedimentation on infaunal invertebrate populations of Cobequid Bay, Bay of Fundy. Can. J. Fish. Aquat. Sci. 38:M2-M8. Warwick, R.M.1986. A new method for detecting pollution effects on marine macrobenthic communities. Mar. Biol. 92:557 562. Warwick, R.M. 1988. Effects on community structure of a pollutant gradient introduction. Mar. Ecol. Prog. Ser. 46:149. Warwick, R.M., T.H. Pearson and Ruswahyuni. 1987. Detection of pollution effects on marine macrobenthos: further evaluation of the species abundance biomass method. Mar. Biol. 95:193 200.
- Warwick, R.M., H.M. Platt, K.R. Clark, J Agard and J. Gobin.1990. Analysis of macrobenthic and meiobenthic community structure in relation to pollution and disturbance in Hamilton Harbour, Bermuda. J. Exp. Mar. Biol.
Ecol.138:119142. Watling, L 1975. Analysis of structural variations in a shallow estuarine deposit. feeding community. J. Exp. Mar. Biol. Ecol. 19:275 313. Watrin, M. C.1986. Larval settlement into marine soft. sediment systems: Interactions with the meiofauna. J. Exp. Mar. Biol. Ecol. 98:65 113. Woodin, S.A. 1982. Browsing: important in marine sedimentary environments? Spionid polychaete examples. J. Exp. Mar. Biol. Ecol. 60:35 45. Young, M.W., and D.K. Young.1982. Marine
. macrobenthos as indicators of environmental stress. Pages 527 539 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. l
-)
i i 102 Monitoring Studies,1993 l I i l
4 m Marine Woodborer Study i n t rod u c t i o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............. 105 Results a nd Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 Conclusions . .................. ..................... ..... .. . . 108 References Cited . . . . . . .. . . . . . . .......... . . . . . . . . . ........... 108 1 Marine Woodborers 103 c 1 I
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1 i j l-104 Monitoring Studies,1993 1 4 1 v
Marine Woodborer Study Introduction our sites. This report covers the first year of collections and data analysis from a redesigned T. Woodborers fill an important niche in marine ansc 14 l ecosystems by degrading wood that is carried l- downriver into coastal waters. Unfortunately, they Materints and Methods l also destroy wooden structures (e.g., boats, piling, !- lobster pots) that have been intentionally placed in Wood panels were submerged approximately 1 l coastal areas. This study considers the wood- m from the water surface at six sites: Efnuent boring effects in Long Island Sound (LIS) of a (EF), Quarry Cuts (QC) Efnuent Buoy .(EB), single genus of marine woodborer, Teredo, which is High Rock (HR), Jordan Cove (JC), and White represented by two species (T navalis and T Point (WP) (Fig.1). The EF site is on the east l bartschi)in the vicinity of Millstone Nuclear Power side of the MNPS cffluent quarry, and panels at Station (MNPS). Teredo navalis is the only QC are located in the quarry cuts, where the shipworm native to LIS; I hanschi is a discharge waters from all three Units enter LIS; semitropical shipworm common from Texas to panels at these sites are exposed to undiluted j South Carolina (Turner 1966), but capable of efnuent. EB is approximately 100 m outside the establishing isolated populations near thermal quarry cuts, when surface pancis receive undiluted discharges in more northern climates. In the discharge waters during ebb tides and ambient tidal 1970s, T. bartschi caused considerable economic waters during Dood tides. HR and JC are damage to marinas within the in0uence of the approximately 500 m outside the quarry cuts, but warm discharge waters of Oyster Creek Nucleat within the discharge mixing zone (2-4 "C Generating Station, NJ (Turner 1973). In July of isotherms: NUSCO 1988) during ebb tides: HR is 1975, I banschi was first documented in the approximately 100 m closer than JC to the channel discharge waters of MNPS (Battelle 1976) and has and the ebb tide path of discharge waters. Large since persisted in the quarry (NUSCO 1993). rock outcroppings at the HR site conceivably cause Teredo banschi was targeted for a principal eddies and altered water circulation patterns, which monitoring effort because it was not common to result in decreased effluent mixing and increased IAng Island Sound waters and it appeared to be water temperatures, which in turn could enhance able to maintain a resident population in the warm recruitment of T. bantchi. WP is the sample site-discharge water of MNPS. Marine Woodborer most distant from MNPS (approximately 1700 m i Studies were redesigned in 1993 to more from the quarry cuts). { intensively monitor the abundance and distribution At EB, HR, JC and WP, two sets of three panch j of I banschi in the immediate vicinity of MNPS. were attached 1 m below 00ats (double lobster pot i increased number of sites and a modified sampling buoys) at each' site and anchored by a weighted (80 I design were selected as a result of data that !bs.) wire lobster pot with no entry funnels (Fig. , suggested I banschi set most successfully on 2). At EF, the buoyed panels were attached to a surface panels,in contrast to the native shipworm, pulley-and line system to facilitate retrieval, and at I navahs, which appears to prefer panels near the OC, panels were attached to a buoy and stiff-arm bottom (NUSCO 1993), system to ensure that the panels remained , The population of Tercdo banschiin the MNPS submerged at the proper depth in the eddy I discharge waters was postulated to have the currents. P4acement of panels in the water column potential of adapting to the cold water
~
(near the surface versus near the bottom) was temperatures common to the winter months of shown to arket shipworm recruitment beyond the LIS, and thus, widening its distribution in the quarry cuts (NUSCO 1991, 1992, 1993). Surface northeast (Hoagland 1981, 1983). The present locations had ended to reduce Teredo navalis study could detect such an event by monitoring settlement and enhance I hanschi' settlement trends in the abundance of this shipworm at all during the 19901992 Discharge Study. Marine Woodborers 105
_ ._ y . . . as c 14 individuals collected on bottom pancis at 100 m in 1985 (NUSCO 1986)_ and a few hundred
\ j
,-~ individuals on surface panels at 100 m in 1990 "C '"""
, , (NUSCO 1991), from 1985 to 1992, T. banschi had d not been consistently collected in panels beyond
, the quarry cuts, either at bottom or surface
" - (= *,,, locations (NUSCO 1993). The HR site was
'5
,,h '
selected specifically for its reduced exposure to rme camem swo, waves and currents, with the expectation that
, - discharge water might be retained in this area for g,, , longer periods of time and favor the setting of T.
banschi. Doochin and Walton. Smith (1951) and . NUSCO (1993) reported that strong currents Fig.1. Lu:ation of woodborer sampling sites in the vicinity of inhibited shipworm settiement.
' Enstone Nuclear Power Station (EF = Emuent . undiluted discharge waters, QC = Ouarry Cuts - 1 m beyond fish t arriers. Teredo banschi was absent from EF in 1993. A EB = 100 m beyond OC, ifR = liigh Rock between rock complete failure in recruitment of T hadscht.
outeroppings about 500 m beyond OC, JC = 500 m beyond oc. during a May to November exposure period had WP = White Point - 1700 m beyond QC. Only occurred once before in 1981 (a 2. unit operational year). The latest absence of I banschi: Each pane! (clear pine 25.4 x 8.9 x 1.9 cm) was at EF, and the low abundance of this shipworm at - secured in a separate section of PVC pipe (35 cm QC, may be related to an atypical set of physical m length x 10.2 mm diameter). The panel arrays conditions of the.MNPS discharge waters during were deployed in May 1993 and collected in November 1993 (redundant sampling was used t 1993. Unit 3 was off line . from Aucust to November in 1993, representing the longesi period mmimtze data loss). Three panels (replicates 1 of 2-unit operation since Unit 3 start-up in 1986c and 2 from one array and replicate 4 from the This prolonged summer shut-down affected both second array, if present) at each site were water Dow (without Unit 3 cooling water flow, the - processed by scraping fouling organisms and debris discharge volume was approximately halved) and from all surfaces, X-raying (250 kV,5 mA, for 45 water temperature (design Er for Units I and 2 s) each panel, and removing all or at least 70 " are 13.9 and 12.7 "C, respectively, compared to 9.5 shipworms per panel. Radiographs were used to
.C for Unit 3) in the quarry. In 1993, the average -
locate shipworms within the panels and to estimate daily discharge temperature in August and total shipworm abundance; shipworms were ' September exceeded 33 "C for more than 14 days. identified after removal from each panel t Adult T. banschi tolerate temperatures of 6-35 "C, I determine the percentage composition of I < but their pediveliger larvae .only remain alive - bansche and T navalis. Shipworms smaller than 5 between 5 and 32 "C (Hoagland 1983). , mm in tube length were classified only as ju enile Water temperature . is 'not the only factor teredinids and, although included as a component ' affecting 7 credo larval behavior and rectuitment; of shipworm abundance, were not included m the settlement has been reported to be mediated by 70 shipworm subsample used for identifications. phototaxis (Isham et al.1951) geotaxis (Isham e't al.1951; Nair 1962) and chemotaxis (Hillman et al. Results and Discussion 1987). As mentioned previously, T banschi tends - to set on panels near the surface (cf. Edmonson in 1993, Teredo barrschi was collected at QC, 1942; NUSCO 1992), and I navalis on the bottom
. EB, and HR (Table 1). The abundance of T.
(cf. Scheltema and Truitt 1956). Teredo banschi bartschi at these three sites was low compared to has a short planktonic life and larvae can settle
' that reported at EF during previous exposure immediately after release (Isham and Tierney panel studies (NUSCO 1993). However,1993 1953), while T. navnlis larvae may delay settlement represents the first occurrence of this species at a for weeks (Grave 1928; Turner and Johnson 1971).
500 m distance from the quarry cuts (HR). Except Both species are affected by strong water currents for three individuals collect:d in surface panels at (Doochin and Walton. Smith 1951 NUSCO 1993).
. 300 m in 1990 (Discharge Study; NUSCO 1991),
106 Monitoring Studies,1993
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PVC PIPE PROTECTOR :
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'w..k m* ' ;.eF w
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Fig. 2. The double buoyed lobster pot deploymens method used to place wood panels 1 m telow the surface at LF. HR, JC. and WP in f the Woodborer Study at MNPS. Panels at OC are paced in a umpling arrays and held m place by stiff arm assembhes and panets at EH .. are placed in samphng arrays and attached I m below the Eftluent Benthic Duce 3 Marine Woodborers 107. I
~
Table 1. Average densily (Ave ) and standard error or mean for shipworms, and associated wood-loss, using surtace panels m the ucmity of MNPS from May to November 1993. SPECtES EF. OC EB 11R JC WP Ave SE Ave. SE Ave SE Ave. SE Ave. SF Ave SE Terrdo banschl 0.0 0.0 15.7 81 0.7 0.7 3.0 0.6 0.0 00 00 0.0 Teredo navahs 34.7 2.9 26.7 1.9 68 3 6.7 38 3 34 14.7 23 64.0 13.7 Teredinid juveniles 0.0 0.0 03 03 3.0 3.0 2.0 0.0 2.0 0.58 5.0 1.5 Percentage Wood. loss 28 3 1.6 273 8.2 55.0 5.0 45.0 8.7 63 0.9 45.0 2.9 It is unclear to what extent these environmental References Cited cues were altered in the quarry as a result of the atypical operating conditions in 1993. It is also Battelle (Columbus Lab., W.F. Clapp Lab.).1976. unclear what effect the retubing of Unit 1 Exposure Panels. Pages Al A20 in A condensers (and concomitant decrease in the use monitoring program on the ecology of the of wood. chips) will have on the population of T. marine environment of the Millstone Point, banschiin the quarry. Connecticut area. As submitted to Northeast In contrast, the continued absence of Teredo , Utilities Service Company. Ann. Rpt., No. banschi panels at WP indicates that this immigrant N673,1975. species has not adapted to ambient water Doochin, H., and F.G. Walton-Smith. 1951. conditions. Although the abundance of untreated Marine boring and fouling in relation to velocity oak piling at White's Dock provides an attractive of water currents. Bull. Mar. Sci. Gulf Carib. food resource for this shipworm, the cold winter 1:196-208. conditions appear too harsh for this species to Grave, B.H.1928. Natural history of shipworm, establish a resident population beyond the Teredo navalis, at Woods Hole Massachusetts. influences of the warm discharge waters. The lack Biol. Bull. Woods Hole. 55:260-282. I of T. banschi in our panels at WP suggests they Hillman, R.E., C. Werme, and M.J. Kenni>h.1987. have not colonized this area, verifying that the EF Setting of larval shipworms Teredo bonschi' population has not yet adapted to survive at Clapp stimulated by malic acid and woodborer j ambient conditions in the Millstone area. metabolites. Technical report to Environr. ental Controls Department, GPU Nuclear Forked Conclusions River, N.J. 25 pp. Hoagland, K.E.1981. Life history chara;teristics Teredo banschi remains in MNPS discharge and physiological tolerances of Teredo banschi, waters. This shipworm was collected at HR, which a shipworm introduced into two temperate tone is the first time 7. banschi has occurred in panels nuclear power plant effluents. In 3rd int. Waste 500 m from the quarry cuts. Reduced currents Heat Meetings Proc.14 pp. around the rock outcroppings at HR may trap Hoagland, K.E.1983. Ecological studies of wood. discharge water and increase the probability of boring bivalves and fouling organisms in the collecting this warm water immigrant. The absence vicinity of the Oyster Creek Nuclear Generating of T. banschi at EF in 1993 is probably related to Station, Final Report. September 1976 - unusual conditions resulting from Unit 3 being off- December 1932. U.S. Nuclear Regulatory line from August to November, during the peak Comm. Wash. D.C NRC FIN B8138.173 pp. recruitment period for this species. The Isham, L.B., F.G. Walton-Smith and V. Springer, distribution of this warm water immigrant remains 1951. Marine borer attack in relation to closely associated with the discharge waters of conditions of illumination. Bull. Mar. Sci. Gulf MNPS and T. banschiappears not to have adapted Ca rib.1:46-63. to ambient conditions at WP,1700 m from the quarry cuts. ; 108 Monitoring Studies,1993 _ _ - - _ _ _ _ _ - -_ O
I 4 1 Nair, N.B.1962. Ecology of marine fouling and wood. Proc. OECD Workshop. March 1968. wood-boring organisms of Western Norway. Organization for Economic Cooperation and , Sarsia 8:1-88. _ Development. Paris France. I NUSCO (Northeast Utilities Service Company). Turner, R.D.1973. In the path of a warm saline 1982. Exposure . Panels. Pages 1-32 in effluent. Am. Malaeol. Union Bull. 39:36-41. 1 Monitoring the marine environment of Long Island Sound at' Millstone Nuclear Power Station, Waterford, Connecticut. Ann. Rpt. 1981. l NUSCO.1987 Exposure Panel Program. Pages 1-45 in Monitoring the marine environment of Long Island Sound at the Millstone Nuclear ; Power Station, Wa terford Connecticu t, S um ma ry of studies prior to Unit 3 operation. Ann. Rpt. q 1986. ' NUSCO. 1988. Hydrothermal Studies. Pages 323 354 in Monitoring the marine environment i of Long Island Sound at Millstone Nuclear Power Station, Waterford, Connecticut. Ann. Rpt.1987. l NUSCO. 1990. Marine Woodborer Studies. Pages 221-242 in Monitoring the marine environment of Long Island Sound at Millstone Nuclear Power Station, Waterford. Connecticut. Ann. Rpt.1989. I NUSCO. 1991. Marine Woodborer Studies. Pages 201 220 in Monitoring the marine environment of Long Island Sound at Millstone Nuclear Power Station, Waterford. Connecticut. Ann. Rpt.1990. NUSCO. 1992. Marine Woodborer Studies. Pages 295-315 in Monitoring the marine environment of Long Island Sound at Millstone Nuclear Power Station, Waterford, Connecticut. Ann. Rpt.1991, NUSCO. 1993. Marine Woodborer Studies. Pages 95 112 in Monitoring the marine environment of Long Island Sound at Millstone l Nuclear Power Station, Waterford, Connecticut. Ann. Rpt.1992. Scheltema R.S.', and R.V. Truitt. 1956. The shipworm Teredo navalis in Maryland coastal waters. Ecology 37:841843. Turner, R.D. 1966. A survey and illustrated catalogue of the Teredinidae (Mollusca: Bivalvia). The Museum of Comparative 7.nology,11arvard U., Cambridge, MA. 265 pp. Turner, R.D. and A.C. Johnson.197L Biology of marine wood boring molluscs. Pages 259 301 in E.B.G. Jones and S.K. Eltringhom (eds). Marine borers. fungi, and fouling organisms of Marine Woodborers '109
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110 Monitoring Studies,1993 s d
Fisti Ecology Studies In trod uc ti o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 13 Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 Ichthyoplankton program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 Entrainment mortality studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 Trawl program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 15 Seine program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 15 Data analyse s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 15 Abundance estimates ...,.................................115 Entrainment estimates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 Results and Discussion ............... .............................. 117 American sand lance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 A n c h ovi e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 Silversides .................................................122 Grubby ...................................................125 Tau tog . . . . . . . . . . . . . . . . . . ..................... . . . . . . . . . . . 12 6 Cu n n e r . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Entrainment mortality studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 Conclusions ................. ...................................130 References Cited ...... ....... .................................. 131 Appendix .......................................................132
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Fish Ecology Studies Introduction occasional overlap in the occurrence of a species during the May June transitional period, species-Fish populations that inhabited the area around specific analyses are based on actual periods of Millstone Nuclear Power Station (MNPS) were occurrence instead of being constrained to the June 1 monitored since 1976 to determine the effects of endpoint. When the season of occurrence of a species station operations. Abundance and distribution of crossed a calendar year, the year was reported as marine fish populations can be affected by water "1992-93", but when the species occurred only within temperature, salinity, density-dependent growth and a calendar year, the year was reported as "1993". mortality, fecundity of individual species, age Materials and methods of the 1992-93 reporting structure of the population and life history strategies. period are essentially the same as those use41 in earlier Moreover, fish species in the MNPS area could be years. adversely affected by losses due to impingement of juvenile and adult fish on the intake screens, entrain. Ichthyoplankton prograrn ment of fish eggs and larvae or by changes in the thermal regime or physical habitat. Long-term Entrained ichthyoplankton (fish eggs and larvae) monitoring is needed to assess the impacts of power samples were collected both day and night three generation on fish assemblages because of the times each week from June through September 1992 inherent variability of fish populations. and once per week from October through December Changes in the abundance and distribution of fish 1992. Sampling was reduced during 1993 after an species which would affect community structure have evaluation of the ichthyoplankton sampling program been defined as power plant related effects. Ichthyo- demonstrated that sample reductions did not substan-plankton, trawl and seine monitoring programs are tially change &mean indices and therefore, did not used to ascertain these effects on local fish popula- reduce the sensitivity of the program to detect changes tions. Additionally, impingement on the intake related to MNPS operations. During January 1993, screens removes juvenile and adult fish from only one day sample per week was col'ected (a populations, although this impact has been mitigated reduction of one sample per week). In February with the addition of fish retums at Units 1 and 3. 1993, samples were collected both day and night one Fish eggs and larvae suffer mortality when they are time per week (no reduction) and in March through entrained through the condenser cooling water system. June 1993, three times per week (a reduction of two Effects of increased mortality rates on the size of fish samples per week). Generally, samples were collected populations depend on size or age at which mortality each week at only one of the three plant discharges occurs, age structure, and the effectiveness of compen- (station EN, Fig.1), with the location usually satory mechanisms. Spatial distribution of local fish alternating weekly between Unit 1 or 2. To collect populations may vary with thermal addition or habitat samples from the discharge water a 1.0 x 3.6 m alterations. Data from the trawl and seine monitoring conical plankton net with 333-pm mesh was deployed programs, on entrained larvae from June 1976 with the aid of a gantry system. Four General through May 1993 and on entrained eggs from June Oceanic flowmeters (Model 2030) were mounted in 1979 through May 1993, are summarized in this the mouth of this net and positioned to account for report along with a brief synopsis of the corres- horizontal and vertical flow variations. Sample ponding sampling program. volume (about 400 m3 in 1992 and 200 m3 in 1993, except during periods of high plankton or detritus - 1 Lterial.t and Methods concentrations) was determined by an average of the volume estimates from the four flowmeters. Species-specific analyses are based on the actual Fish larvae were also collected in mid-Niantic Bay ! periods of occurrence instead of being constrained to at station NB during 1992 (Fig.1). Two day and two l June 1 as the common starting point. A reporting night samples were taken weekly from April through 1 year comprises the 12-month period from June of one August, and one day and one night sample were taken year through May of the following year. Because of biweekly from September through December. Fish Ecology 113
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1 Samples were collected with a bongo sampler (two of dissecting microscopes. Successive splits were 0.61-m x 3.3-m conical plankton nets). De bongo completely sorted until at least 50 larvae (and 50 eggs -- . sampler was towed at approximately 2 knots for 6 to for samples processed for eggs) were found, or until ~ j 15 minutes using a stepwise oblique pattern with one half of the sample _was examined. ~ Samples equal sampling time at surface, mid-depth, and near- examined for larvae included all NB samples and all.- bottom.- Sample volumes were measured using one EN samples collected from January through May and
-' General Oceanics flowmeter in each net and approxi- July through December. In the June samples, only? ,
mately 300 m3of seawater were filtered for each two (one day and one night) EN samples per week . 1 sample (except during periods of high plankton or were examined. nree _ day and three night EN samples - : detritus concentrations). Net mesh size was 333 pm, collected in April through September were examined '
- except during a period from mid-February through for fish eggs. Fish eggs and larvae were identified to .r March, when 202 m mesh nets were used to . the lowest practical taxon.1. Wrasse (tautog, Tautoga -
., minimize the extrusion of yolk-sac winter flounder onitis and cunner, Tautogolabrus adspersus) eggs 1- larvae. Sampling at NB was discontinued in 1993.' ' were distinguished from a weekly composite sample - Plankton samples were split using a NOAA-Boume - of their eggs using the criterion of bimodality of egg ' splitter (Botelho and Donnelly 1978); ichthyo- diameters (Williams 1967). ' lchthyoplankton {* plankton were removed from the samples with the aid densities are reported as number per 500 m . 114 Monitoring Studies,1993 2 e , , - - - - . , - - . . _ _ - . _ - - - - _ _ _ . _ - _ . _ - _ - - - - . _ _ . - - - - . _ ~ - -
Entrainment monality studies only two replicate tows were taken at a station because of damage to gear or severe weather. A Special studies to estimate wrasse egg entrainment standard tow was 0.69 km and this distance was monality were conducted in 1993. To decrease the measured using onboard radar. When the trawl net volume of water filtered through the plankton net and became loaded with macroalgae and detritus, tow reduce the pressure on the eggs in the net, a 20.5 cm distances were shonened and standardized 100.69 km. Pitot tube sampler was deployed using the same Catch was expressed as the number of fish per gantry system used in regular entrainment collections standardized tow (CPUE) Up to 50 randomly chosen at the discharge (Fig. 2). One General Oceanic individuals of cenain selected species per station were (Model 2030) flowmeter was positioned inside the measured (total length) to the nearest millimeter. Pitot tube to determine the sample volume. A tight mesh nylon sleeve was secured around the net to Seine program reduce the sheer on the net which could damage the eggs already caught in the net. These studies were Shore-zone fishes were sampled using a 9.1 x conducted June 2122, June 22 and June 28-29. 1.2 m knotless nylon seine net of 0.6-cm mesh. Samp!cs were also collected in front of the MNPS Triplicate shore-zone hauls were made parallel to the intakes in Niantic Bay (IN) and were used as a control shoreline at White Point (WP), Jordan Cove (JC), and to determine natural and sampling monality. At IN, Giants Neck (GN) monthly from November through the sampler was placed in a styrofoam float and towed March and biweekly from April through October at a similar velocity as encountered at station EN. (Fig.1). A standard haul distance was 30 m. Samples were brought to the laboratory, placed in Collections were made during a period 2 hours before running seawater and viewed immediately with a and I hour after high tide; generally all three stations dissecting microscope. Approximately 100 wrasse were sampled the same day. Fish in each haul were eggs were removed from samples collected at each identified to the lowest possible taxon, counted, and station. Ten eggs were put into each of ten 30-mL the total length of up to 50 randomly selected Nalgene@ beakers with three 1.5 cm diameter individuals of each species from each replicate were openings covered with Il0-pm mesh netting and measured to the nearest millimeter. Catch was placed in a floethrough sea water bath. Samples expressed as number of fish per haul. were viewed at 1 cast once per day to determine how many eggs had hatched; eggs that had not hatched at Data analyses the end of a 72 hour period were considered to be dead. After hatching, larvae were identified to species. Abundance estimates To determine daily fluctuations in abundance, three 24-hour studies of wrasse egg densities were con- The occurrence, distribution, and abundance of ducted Jurie 8-9, June 15-16 and July 19-20. A total selected potentially impacted fish, as well as their of 39 samples were collected at EN (using sampling observed spatial and temporal fluctuations, were methods described above for the 1 m 333- m mesh analyzed to assess possible plant-related impacts. net) every 2 hours during a 24 hour period. Indices of fish abundance were selected on the basis of Approximately 100 eggs were removed from each underlying distributional assumptions; failure of the sample and identified as cunner, tautog or other data to conform to these assumptions may reduce the species. Densities were reponed as number of eggs precision of the estimates or, worse, provide biased per 500m3. results. Thus, the A-mean was used as an index of abundance and the a parameter from the Gompertz Trawl program function was used to estimate entrainment of fish eggs andlarvae (NUSCO 1990). Triplicate bottom tows were made using a 9.1-m The A-mean was selected to describe annual otter trawl with a 0.6-cm codend liner. Demersal abundance trends because it is the best estimator of i fishes were collected biweekly throughout the year at the mean of a population that approximately follows six stations: Niantic River (NR), Jordan Cove (JC), the lognormal distribution and contains many zeros Twotree Island Channel (TT), Bartlett Reef (BR), (Hennemuth et al.1980; Pennington 1983, 1986). Intake (IN) and Niantic Bay (NB) (Fig.1). Rarely, The calculation of this index and its variance estimate Fish Ecology 115
4 Top View
/ s n 1.52 m e i e ....' K g9 ~.... '
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116 Monitoring Studies.1993
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was described in detail in NUSCO (1988). The A- nonlinear regression methods (SAS Institute Inc. mean was used as an index of abundance for juvenile 1985). He cumulative data .were obtained as the and adult fish collected in trawl and seine prognuns, running sums of the weekly geometric means of the for larvae and fish eggs collected at EN, and for larvae abundance data per unit volume. collected at NB, The A mean indices of ichthyo- A " density" function was derived algebraically by plankton species were weighted by the largest number calculating.the first derivative of the Gompertz of samples collected in a week to standardize data function (Eq.1) with respect to time. This density across weeks and years. For any species that occurred function, which directly describes the larval abundance seasonally, the data used for calculating the A mean over time (abundance curve), has the form: were restricted to its period of occurrence to reduce the number of zero values in the distribution tails. Two- d, = a'k exp(-exp[ k[t -p)] -k[t -p]) (2) unit operational period A-means were calculated from where a' equals 7a because the cumulative densities the beginning of two-unit operation (1976) to the were based on weekly (7-day period) geometrie means, beginning of three-unit operation (1986). d, is density on day I and all the other parameters are as described in Equation 1. Entrainment estimates Daily entrainment was estimated by multiplying these daily densitics di by the daily volume of cooling Entrainment estimates of dominant ichthyo- water that passed through MNPS. Annual entrain-plankton were calculated from daily density estimates ment estimates were determined by summing all daily at EN. These estimates were determined from a estimates during the period of occurrence. Gompertz function fitted to the entrainment data. De distribution of egg and larval abundance over time is Results and Discussion usually skewed because densities inemse rapidly to a maximum and then decline slowly. De cumulative One hundred and twenty species of fish eggs, density over time from this type of distribution larvae, juvenile and adult fish were collected in the resembles a sigmoid-shaped curve, for which the MNPS monitoring programs from June 1976 through inflection point occurs at the time of peak abundance. May 1993 (Appendix 1). Winter flounder ne Gompertz function (Draper and Smith 1981) was (Pleuronectes americanus), anchovies (Anchoa used to describe the cumulative egg and larval mitchilli and A. hepsetus), silversides (Menidia-abundance distribution to insure that the inflection menidia and M. beryllina), grubby (Myoxocephalus point was not constrained to be the mid point of the acnaeus). American sand lance (Ammodytes sigmoid curve as is the case in the frequently used americanus), skates (Raja crinacca, R. ocellata and R. logistic and probit curves. The form of the Gompertz eglanteria), scup (Stenotomus chrysops), windowpane function used was: flounder (Scophthalmus aquosus), tautog and cunner were the most common fish collected. C, = u exp(-exp[-k[t-p)]) (1) Sixty-one taxa were represented in ichthyoplankton where samples and of these 7 egg and 20 larval taxa were C, = cumulative density at time i found in sufficient numbers to calculate A-mean t = time in days from the date when the eggs or densities (Tables 1, 2, and 3). All 1992 93 egg larvae generally first occur densitics at EN were within historic ranges. a = total or asymptotic cumulative density However, densities of winter flounder larvae at EN p = inflection point in days since first occurrence were the lowest ever recorded since sampling began in date 1976 77, and densities of anchovy larvae at EN and k = shape parameter NB were the second lowest recorded with' only densities in 1987-88 lower. Except for winter The origin of the time scale was set to the date when flounder larvae, other egg and larval entrainment-the eggs or larvae generally first appeared in the estimates were within historic ranges. waters off MNPS, least-squares estimates, standard Over the past 17 years,105 fish taxa were caught errors, and asymptotic 95% confidence intervals of in trawls and 50 were captured in seines (Appendix I). these parameters were obtained by fitting the above Six taxa in trawl samples and one taxon in seine equation to the cumulative abundance data using samples accounted for over 80% of the catch in each Fish Ecology 117 l
c TABLE 1. The A-mean* density (noJ500 m ) 3of the most abundant fish eggs collected at EN for each report year from June 1979 through May 1993 (two unit operational period.1976 85; three unit operational penod:1986-93).
'Intm 79-80 8041 8142 Bb83 83 84 84-85 8546 8647 8748 8849 69-90 00-91 91-92 92-93
- 7. adspersar 5,870 8223 5,171 5,501 7,068 5,719 7,484 2,969 5,002 5,395 6,904 4,998 6,954 4,416 <
T. cadis 1.364 2,842 2,647 2,244 2,114 2,157 3,237 2,756 3.011 2,269 2,887 2,060 1,878 1,449 Anchos spp. 1,447 1,245 1,080 765 2.257 4,880 145 910 89 38 54 127 476 107 S.aguosar 50 63 65 34 19 71 365 181 520 178 94 76 64 72 Prionotur spp. 61 206 398 385 425 156 367 82 63 89 64 15 14 52
- 3. chrysops 21 1 133 113 98 194 25 69 31 4 36 19 23 34 E eimhnus 22 11 31 34 8 10 14 55 58 65 65 24 117 86
- Data seasonally restncted to May 224uly 23 for T adspersus, May 23. August 25 for T.oadir, June 15 August 5 for Anchoa spp.,May-August for S. agnosus, July-August for Prionotar spp., MayJuly for S. chrysops, and April August for E. cimbnar.).
S TABLE 2. 'Ihe A-mean* density (noJ500 m ) of the most abundant fish larvae collecte.d at EN for each report year from June 1976 through May 1993 (two-unit operational period:1976-85; three-unit operational period:1986-93). Taxon 76-77 77-78 78-79 79-80 80-81 81-82 82-83 83-84 84 85 85-86 86-87 87-88 88-89 89-90 90-91 91-92 92-93 Anchoa spp. 1,152 931 483 2,168 2,430 5,768 816 1,421 302 1,102 1,244 126 359 619 1,122 799 178 P. americanar 106 143 114 285 129 233 277 210 180 87 109 116 203 106 99 388 21 . A. americanus 94 318 119 111 136 21 27 18 9 3 13 41 31 24 7 18 28 M. senaeus 41 38 36 38 107 72 68 50 68 34 29 95 63 30 24 58 34 P. guamellus 13 13 16 13 58 27 13 14 14 22 4 26 9 6 3 15 8 . B. tyrannus 5 4 4 0 3 1 11 23 2 41 3 2 6 72 18 97 41 T. adspersur 29 58 1 13 58 78 31 49 4 12 4 5 9 14 68 209' 8 T. oruth 37 36 1 11 46 83 44 33 3 15 3 7 17 15 33 99 13 liparis sy, 27 30 10 16 22 5 13 8 36 1 4 42 18 12 3 23 14 U. subbfuncata 5 9 14 14 16 17 6 4 60 7 9 23 41 51 34 28 2 S.fuscus 4 7 4 9 8 13 7 9 9 5 4 6 7 5 3 5 3 E. cimbrius 2 8 6 8 6 1 6 13 5 8 8 12 45 31 37 98 5-S.aguarar 10 11 1 5 5 5 2 13 3 1 4 3 5 3 4 12 2 P. sriacoashar 14 3 1 2 11 17 9 9 1 2 3 0 9 5 29 10 2 Gobiidae 6 3 1 0 1 0 0 1 4 3 3 2 4 8 7 12 2 Prionocur spp. 2 2 0 1 3 18 0 4 1 6 0 0 1 1 7 3 0 M. oefalecemspinarur ! I i 1 1 3 4 4 1 0 0 0 1 1 0 2 0 S. chrysops 5 8 0 4 6 8 1 0 0 0 0 0 0 2 0 0 0 C. krangus 1 1 1 0 6 1 0 1 0 2 1 14 1 1 2 9 7 prerahr 1 3 0 6 0 7 6 3 0 2 1 0 1 1 0 0 0 Data seasonal)y restncted to July-Sepember for Anchoa s March. June for P. amenceaus, December May for A. americanar. February-May for M. assacus, January May for P. gunnellus. Jul cember for B. tyrannus, to June-August for T, a&persus, June August for T. onitis, Marth-May for Liparar spp., April-September for .fuscus, AprilJune ior U. subb(urcato, AprilJuly for E. cimbriur, May-October or S.aquosus, June-September for P.triacanthat, June November for Gobiidat, June September for Prionorus spp., January-May for M. ocialecemspinosar, June August for S. chrysops, February-May for C. krengar and June-August for C. regali.r. s TABLE 3. The A-mean density (noJ500 mS) of the most abundant fish larvae collected at NB for each report year from June 1979 through May 1993 (two-unit operational period:1976-85; three-unit operanonal period:1966-93). Jasm 7940 80 81 8142 8243 8344 84-85 8546 8647 8748 8849 89-90 90-91 91 92 92-93 AncAou spp. 3,801 5,716 7,873 2,103 2,800 327 1,117 1,224 79 3 03 462 1.214 711 181 P. americanar 222 129 158 317 187 85 80 146 147 111 109 128 364 .. b . A. americaans 113 238 20 54 58 8 3 13 83 35 16 5 9 .. b T. adspersur 92 143 96 151 198 37 30 8 10 28 39 .141 282 19 i M. annaeus 31 54 28 39 24 18 26 28 119 44 25 23 72 .. b T. oaitis 49 89 91 110 119 28 44 12 13 29 28 60 123 25 E. cimbrius 19 10 3 24 19 23 9 11 19 54 42 90 - 131 17 B. tyrannar 0 2 2 36 9 24 12 0 1 1 4 1 4 5 S.aguosur 24 12 7 17 30 14 5 8 7 10 7 12 13 5 P. gunnenar 5 24 14 7 8 2 8 1 7 5 5 1 9 ..b P. sriacanthus 9 18 37 31 35 2 18 6 1 11 8 54 15 2 lipars spp. 12 23 4 15 4 14 1 5 59 12 18 3 29 -.b 3.fuscus 5 7 9 5 12 7 2 2 4 4 2 1 5 2 . U.subbfurcara 10 9 20 8 5 7 5 6 11 12 32 9 7 ..b Prionosus sm. 5 4 34 13 8 3 7 5 0 2 2 16 6 2 M. ocsodecemspiaatus 2 3 4 6 4 1 0 1 1 I 1 0 3 b P. oNongus 1 3 8 6 9 1 5 1 1 3 3 4 4 2 C. regatas 6 0 11 ' 13 0 0 1 1 0 0 1 0 1 0 i cArvses 9 16 6 1 0 0 0 0 0 0 1 2 7 1
- Data seasonally restricted to July-September for Anchos spp., to MarchJune for P. americanus, December May for A. americanus, June-August for T. adspersar, June August for T. caitis February Ma May-October for S, aguosus, Jnnuary-May for P. gunnellar,y June-Septemberfor M.foraosaeur, July Decemberfor P. triacanthat, March-May for BJyrannar, Liparis AprilJulyfor E. cimbr September for S.fureur, June-September for Priososur spp., AprilJune for U. subbifurcata, January-May for M. octodecem arar, June-August for P. oblongus, June-Augurt for C. regali.r, June August for S. chrysops, b
Sampling at NB was discontinued aftes December 1992 thus no data was obtained for these species during the report year 1992-1993. 118 Mordtoring Studies,1993 '
TABLE 4. The A means catch (noJ0.69 km) of the most abundant fish couected by trawl for each report year from June 1976 through May 1993 (two-unit operational period;1976-85; three. unit operational period:1986-93), 7677 77-78 7879 7940 8081 81 82 82 83 83 84 8485 8546 8687 8748 8849 8990 9091 9192 92 93 laxon
- f. ameracanar 16.6 13.5 16J 26.8 32.6 24.1 41.8 27.7 29.5 22.u 19.8 19 3 26.2 18.2 19.1 17.1 17.3 S. cArysops 10.6 19.8 13 3 18.5 17.0 20.4 27.5 26.6 223 13.6 30.6 21.7 18,0 14.5 120.9 212.0 63.4 Anchoa spp. 11.1 33 393 0.1 al 4.0 0.2 0.4 0.7 113.8 57 3 1.6 3.1 15.9 0.0 0.6 0.6
- s. oguarar 2.9 2.4 1.8 2.9 3.5 2.9 6.7 5.0 4.4 43 3.8 4.0 5.1 5.7 3.5 1.8 2.9 Raja eg. 1.4 1.2 0.8 0.8 2.0 1.4 6,1 5.3 3.1 8.5 4.5 4.6 63 53 6.3 6.4 3.9 MidA2 rm ' 16.2 97 2.8 6.2 6.5 la 1.5 11 0.5 1.9 17.8 13 34 1.9 1.8 59 13 4
- Data seasonally restncted to June. October for s. chrysopr, August. October for Anchoa spp., October. February for Menad4a spp., and the remaining tasa year-round (June-May).
monitoring program (Appendices 11, Ill, IV and V). May 1993 (Table 5). Anchovies, winter flounder, Winter flounder continued to dominate the trawl American sand lance and grubby accounted for 80% of catches, accounting for 37% of the catch from 1976- the entrained larvac during the same period (Table 5). 77 through 1992-93, and 29% of the catch during Except for winter flounder , entrainment estimates 1992-93 (Appendix II). During two-unit operations of eggs and larvae were within historic ranges (Tables winter flounder accounted for 41% of the trawl catch 6and7). Although the volume of cooling water but only 31% of the catch during the three-unit pumped through MNPS during the 1993 season of operational period. Scup also comprised 29% of the occurrence for winter flounder was the highest catch during 1992-93 and 21% from 1976-77 through recorded, the entrainment estimate was the second 1992-93. During the two-unit operational period lowest recorded. Only the 1977 entrainment estimate scup only accounted for 14% of the trawl catch but was lower but the cooling water volume during the j increased to 28% of the catch durirg the three-unit 1977 larval season was only 40% of the 1993 ' operational period. In 1992-93, wir lowpane flounder volume. The winter flounder entrainment estimate 1 and skates accounted for 5% and 6%, respectively was low due to the low density of lar ne- j which was just below the 17 year (1976-77 through ' 1992 93) average of 7% each. During two-unit operations windowpane flounder accounted for 8% of the trawl catch while skates accounted for 5.8%. TABLE 5. Taxonomic composition of ichthyoplankton coIIected at EN (as a percentage of the total) from June 1976 through May These percentage were reversed during three-um.t 1993 fc.r larvae sad April 1979 through Sepember 1992 for eggs. operations with windowpane flounder accounted for 5.8% of the catch and skates accounting for 8%.
.r-Aachoa s w55.2.- %
6.6 More silversides were collected by trawl in 1992-93 Q','pp,',"8 P
'*"i'd a "'
ly 8j than in the previous 17 years (1976-77 through upoxoc,pha[wsenaur 4.5 0.0 1 1992-93). llistorically (1976-77 through 1992-93) 37 00 8"voo' Tautogolabru '/'aa*"' airper,us 2.4 55.6 silversides have accounted for 4% of the trawl catch raurosa onins 2.1 303 but this year (1992-93) they accounted for 11% of the M',*y#"' ,% [j @j catch. The percent contribution of silversides to the Ulvario subbi/wrcata 13 0.0 trawl catch increased from 4% during two unit operations to 5% during three-unit operations. Only g'g, scophtAatmus , quo,ur [9 2 0.8 gj 2.4 0.2% of the catch in 1992 93 were anchovies, although historically (1976-77 through 1992 93) {'g#iacda'A"' gj y ciupta Aarengw 0.4 RO they have accounted for 6% of the catch. The A-mean y',ioad"'g j32 for each of these taxa were all within the range of s,, oromar cary,opr 0.2 N 0.7 previous trawl catches (Table 4). dominated seine catches accountir:g for 81% of the Silversides {*,'$h'g*6'oasu' @j jj cynarcioa r<garir 0.1 al catch from 1976 77 thrcugh 1992 93 and 93% of the S'aa6" " o=6*"' al at
. . Anguilla rarrata 0.1 0.0 catch in 1992-93 (Appendix IV). During the two-umt Atosa , al as operational period silversides accounted for 85% of Q,u gj gj the catch and 78% of the catch during the three-umt s rois,s macutasar al 0.0 operational period. jP,A it spp. gj gj Cunner, tautog and anchovies accounted for over Atara p,,udohar,ngar 0.0 0.1 90% of all eggs entrained from June 1976 through Fish Ecology 119
'I i
)
TAllLE 6. Estimated number of cunner, tautog, and anchovy eggs entrained each year at MNPS and the volume of cooling water on which j the entramment estimates were based (two-unit operational period;1976 85; three-tuut operational period 1986-92). Cunner 'I autor Anchovy Yeat No. entramed Volume (m3r No. entramed Volume (m3 r No. entrained Volume (m3 r (x106) (x 106) (x106) (x 106) (x106) (x 106) 1979 1,534 728 705 728 215 711 1980 2,302 806 1,273 806 91 795 1981 1,736 816 1,735 816 172 799 1982 2.726 853 1,486 853 234 843 1983 2,631 798 1,180 798 618 786 1984 2,031 827 1.369 827 652 812 1985 2,802 831 1,784 831 20 825 1986 2.932 1,870 3,907 1,870 517 1.846 1987 4,533 1,784 3,740 1,784 37 1,752 1988 4,386 1,953 2,813 1,953 16 1,920 1989 3,885 1,643 3,094 1,643 5 1,611 1990 3,651 1,823 2.185 1,823 28 1,795 1991 4,758 1,265 1,589 1,265 147 1,247 1992 2 736 10'2 1 271 1 022 17 10'2
- Volume was determined from the condenser cooling water flow at MNPS during the season of occunence for each taxa.
TABLE 7. Estimated number of anchovy, winter flounder, American sarid lance and grubby larvae entrained each year at MNPS and the volume of cooting water on which the entrainment estimates were based (two-unit operational period:1976 85; three-unit operadonal period:1986-93). Anch ovv Wmter Flounder American rand lance Grubbv Year No. entramed Volume (m3r No. entramed Volume (m3r No. entramed Volume (m3r No. entrained Volume (m r 3 (x106) (x 106) (x106) (x 106) (x106) (x 106) (xtos) (3306) 1976 419 616 108 663 20 839 13 625 1977 424 570 31 586 84 9s3 32 653 1978 173 657 87 491 190 808 11 446 1979 887 552 48 474 154 941 21 534 1980 918 505 176 633 124 1,090 34 702 1981 1,784 633 48 455 90 713 43 414 1982 464 550 170 674 32 1,065 49 629 1983 623 482 219 648 41 1,127 57 704 1984 169 602 88 574 20 981 41 643 1985 712 601 83 528 10 1,031 37 582 1986 1,328 1,259 131 1,353 5 1,734 56 1,286 1987 124 1,161 172 1,324 48 2,186 55 1,370 1988 396 1,338 193 1,382 126 2,036 124 1,273 1989 546 1,201 174 1,046 55 1,927 72 1,110 1990 1,025 1,272 139 1,303 61 2,242 49 1,335 1991 478 786 121 934 7 1,330 34 1,024 1992 174 1,018 514 1,199 32 1,672 76 1,132 1993 - it - 45 1412 50 2261 54 1 374 a Volume was determined from the condenser cooting water flow at MNPS during the season of occurrence for each taxa. b Not calculated because larvae occur after end of report pericx! (May 1993). Additional data analyses were completed for six taxa trawl or seine. Larval catches are variable and annual that were identified as having a potential for impact entrainment estimates ranged from 5 to 90 million based on their prevalence in entrainment samples or larvae, "Iheir abundance has varied over two orders of susceptibility to thermalimpacts. Winter flounder is magnitude during the past 17 years (Table 8), Larval discussed in a separate section (see Winter Flounder densities during two- and three unit operational Studies), and is not included among these fishes. The periods were compared to assess annual variation A mean densities (no/500m3) for eggs and larvae, A. (Fig,3), Because sand lance larvae were so abundant - mean catches (noJ0.69 km) for trawl catches and from 1976-77 through 1980-81, larval densities in the - (no/30 m) for seine monitoring programs were calcu- three-unit period have been lower than during the two-lated for abundant life stages of American sand lance, unit period. The 1992-93 densities of sand lance anchovies, silversides, grubbies, cunner and tautog. larvae were within the range of densities from recent years, Given the large abundance changes of this American Sand lance species along the Atlantic coast (Monteleone et al, 1987), effects of MNPS operation on sand lance are American sand lance are caught primarily as larvae difficult to ascenain. in the winter and spring and are seldom caught by 120 Monitoring Studies,1993
TABLE B. He A mean sdensity (noJ500 m 8) and 95% confi- TABLE 9. De 4 mean* density (no/500 m3) and 95% cmfi-dence interval for American sand tance larvae collected at EN dence interval for anchovy eggs and larvae collected at EN and during each report year from June 1976 through May 1993 (two-larvae collected at NB during each report year from June 1976 unit operational period: 1976 77 through 1984 85; three unit through May 1993 (two-unit operational period:1976-85; three-opersuonal period: 1985-86 through 1992-93). unit operational period;1986-92). Year EN EGGS LARVAE 1976 77 941 17 Yent EN EN 1977 78 3181117 1976 1,152 1419 1978 79 119125 1977 9311408 1979-80 til1 26 1978 '4831 206 1980-81 136132 1979 1,4471 336 2,1681908 1981 82 21 14 1980 1,245 1 597 2,4301 1,249 1982-83 2718 1981 1,080 1 264 5,768 1 3,326 1983 84 18 14 1982 7651 228 8161240 1984 85 912 1983 2,257 1 1.076 1,421 1 530 1985 86 311 1984 4,880 1 3.680 3021165 1986 87 13 14 1985 145 175 1,102 1453 1987-88 41 113 1986 910 1547 1,2441893 1988-89 31113 1987 89146 1261 69 1989-90 2417 1988 371 33 3591 216 1990-91 712 1989 54147 619 1416 ' 1991 92 1816 1990 127 1 117 1,122 1 853 1992-91 ?8 + 10 1991 476 1 526 7991801
- Data seasonally restricted to December May. 1492 IM + 112 178 + 85
- Data seasonally restricted to June 15 August 5 for eggs and July - September for tarvae.
aso . 200 - e 3-Uf4T S Ut#T C PERIOD PERICO l N- Ecos 350 - , AT EN e E 5 -- : } eooo- :
- __________ t__ :
a ,, a ,e a s, w as aa,oarvu a aa,as A# as. w a. 8- : v y ------- Fig. 3. He annual (-) A-mean densities (noJ500 m3) of American sand lance larvae at EN during two-urut and three-unit oLr4 is is i i ii.iiiii so sa sa se se iso Mier operational periods, he two-unit operational pericd (19761985) sooo. gyg , A-mean density is represented by the flat line ( ) AT EN e which is extended over the 3 unit operational period as a l reference level. Arichovies E aooo- ! t l 2 . The bay anchovy is the most common fish along g acoo _ ; f the Atlantic coast and the most abundant ichthyo. y --------- plankton member within its range (McHugh 1977; , / Leak and Houde 1987). Larval anchovies dominate 4'5'E'a'4'a'E'E'E "^" the plankton collections and anchovy eggs.were ranked third in abundance. The entrainment estimales Fig. 4. De annual (-) A-mean densities (noJ500 m2) of of eggs and larvae for 1992 were within the historic '"',hp,%8 ,lgac al,,unitEN""8N
- range (Table 6 and 7). The 1992 anchovy egg density
,, a $'h8 )
A-mean density is represented by the flat line ( ) was within the range of densities sixe 1984 (Table 9; which is extended over the 3 unit operational period as a
'*#*'** I"*I' Fig.4), All egg densities during the three unit opera-tional period were below the two-unit average because after 1984 (before the three-unit period) densities unit larval A mean densities were below the two-unit declined by one order of magnitude and remained low, A-mean average (Fig.- 4). Juvenile anchovies resulting from the summer spawn are typically Larval densines in 1992 were the second lowestewith only the 1987 densities lower (Table 9). All th:ee- captured by trawl sampling from August through Fish Ecology 121
October, predominantly in Niantic Bay. Even though two-unit A mean average (Fig. 5). All three-unit anchovies rank fifth among fish caught by trawl, A. annual A means were above two unit average at NR. mean CPUE could not be calculated because The A-mean catches of Atlantic and inland silvers *s anchovies catches were highly variable. More than caught in seines were all within historic ranges (Fig. 70% of all the anchovies caught during the past 17 6; Table 11) and all 1992 A means were ateve the years were caught in only 2 years,1985 86 and 1986-77,(Appendix II). Anchovies mature within a few lg g months of hatching and live only 1 or 2 years; such - m short-lived species usually exhibit large oscillations f- \,, l in abundance. ' a l e Silversides E x-h 20 - Along the Connecticut coast, the Atlantic silverside 0
, g { - - - - ~~ ~ ~ ~ ~
and the inland silverside are the most common shore-0 w g_ j zone species. The Atlantic silverside is the most 3' y ' 3'3 ' ,,',,',, ,,' , ' ,' ,',,' ,i,,i ,,',,i ,,',, dominant. Essentially, all the silversides caught by - trawl wem the Atlantic silverside; less than 0.1% N * "' caught in the past 17 years were the inland silverside. r l llistorically, more than 80% of the silversides I so - l collected by seine were Atlantic silversides, although this pmportion has varied from year to year. Both { x_ l g l species are so abundant in the shore zone that they 3
/ l__
can be analyzed separately. Trawl and seine catches '0 -
- are highly variable and annual catch indices ranged o , , ,,,,,,, , , ,
over two orders of magnitude, which is typical of a n n n e>ei aasa e4as eSer esse seei e2.e3 short lived species such as these. The A mean trawl #- Na . CPUE for Atlantic silversides was at a 17 year r 80 - l (1976-77 through 1992-93) high at the two Niantic 2 e. l Bay Stations (NB and IN)(Table 10). This was the R
.l first time in the three unit operational period these E "- l two stations were above the two-unit average (Fig. h 20-l 5). All 1992-93 A-mean trawl catches were above the s
0 to . 0 h ,Y,, l TABLE 10. The a mean catch (noJ0.69 km) and 95% conn. , , r , , dence interval for Atlantic silverside cotlected by tnwl at 7&n 757e sosi 82 s3 e4-as esa7 asas cost e2 e3 selected stadons during each report year from June 1916 through so May 1993 (two-unit operadonal riod; 1976-77 throu h 1985 4 6; .sc , three-tadt operational period: 19 6 87 through 1992 9 ). ,,. ; Broort Year IN JC NB NR $ g. l 19 4 71 15116 131 20 618 772 283 R ' 1977-78 291 92 61612 181 25 101 21 g z. l 1978 79 601 105 918 817 211 . 1979 40 421 276 6117 0.712 416 h 20- ' 1980-81 8117 415 191 42 314 5 l 1981-82 619 110 516 618 to-Q , 1982 41 1983 44 1984 45 214 214 216 112 411 S i ll 1112 411 til 1215 116 111 0- i i ,,,,,,--,,M,,,,--,y', 75n nn sosi s2 3 e4 ss ass 7 saae sosi eres 1985 46 718 618 211- 316 REPORTYEAR 198647 513 817 413 1101222 198748 325 212 314 151 27 Fig. 5. The annual (-) A-mean densides (noJ0.69 km) of 1988 89 211 lio 110 251 14 Atlantic silverside taken by trawl at NR, IN, NB and JC during l l h two unit and three-unit operadonal periods. The two-unit 1991 92 121 10 211 513 19 17 operadonal period (19761985) 4-mean density is represented by 1992-93 115 + 156 7+2 24 + 19 24 + 15 the flat line ( . ) which is extended over the 3-unit
- Data seasonally restricted to November February at IN, NB opendonal period as a reference levet
, and NR, and Octoter January at JC-122 Monitoring Studies,1993
l j l ATLANTIC SILVERSIDE INLAND 84LVEftSJDE 84MT S447 8.UMT SENIT PERICO Pf>1100 PERIOD PERICO JC **' JC . e a
- - = l
[~ '" ~ \ : I :
'\
g ,, . __ ________ g,. .
~
a
# . A n- l 6
=- ! Y 6 l
o , , , , , , . . , , , , . , , , , , , , , , , , . 81 83 85 87 80 81 81 83 85 87 88 81 200 - wp , W wp ,
, e l e-e tw- . .
g . e i . g. . 100., D l D n- l s : a : m- , o . , i
\r ,p ___ , , , , , , , oi i-r- i .- Y"T -
"r =T- -i ' - , - i 81 83 $$ 87 88 81 at 83 85 87 88 81 3
""m ,
"*m .
iso - x k soo. k. l h h m- l a-M________U _____
~
0 -- , , , 81 83 85 87 0
- TT i i i ~i ---______ a a i i i s Sa 81 81 83 85 47 88 Si YEAR YEAR Fig. 6- he annual (-) A mean densides (no/30 m) for Atlantic suverside and inland silverside taken by seine al JC, WP and GN during two-unit and three-unit operational periods. %c two-unit operational period (1976-1985) A-mean density is represented by the flat lanc ,
( ) which is extended over the 34: nit operaticmal period as a reference level. two unit average, except for Atlantic silversides at JC To determine if a change in length-frequency - which was typical for all three-unit operational A- distributions occurred after Unit 3 became operational, means. IIistorically, Atlantic silversides were more the length frequencies (expressed as percentages) were abundant than inland silversides, however during 1990 examined for the periods before and after three-unit and 1991 inland silversides were more abundant than operation and for the 1992-93 study period. The Atlantic silversides at JC (Fig. 7). In 1992, Atlantic length frequency distribution for silversides collected silversides again dominated the catch at JC but by seines and trawls remained similar during these catches of both species were within historic values, two operational periods (Fig. 8). Fish Ecology 123
TABLE 11, lhe A-mean catch s (no/30 m) and 95% confidence interval for Atlantic silverside and inland silverside collected by seine during each nport year from June 1981 through May 1993 (two-unit oper:6 anal period.1976-85; three unit opera 6cnal period:1986-93). Athntie nuvdde inhnd suverside Year JC GN WP Year JC GN WP 1981 152 1 251 83178 321 49 1981 313 lil 113 1982 lidt162 462 109 1571526 1982 6116 112 91 44 1983 3971598 35149 1091153 1983 881243 315 113 1984 291 24 181 11 311 1984 312 til 010 1985 19 112 541 45 514 1985 418 010 010 1986 1721 385 58146 1619 1986 14121 212 115 1987 1091 90 50127 (6 186 1987 312 til 010 1988 M1108 361 34 361 23 1988 27154 lit 110.5 1989 70 13 9 361 34 33 122 1989 141 16 112 6128 1990 83 108 70144 651 52 1990 1331234 14124 431 148 IW1 38111 61115 72134 IW1 74137 1019 917 1992 78155 681 30 101 170 1992 431 27 311 110.3 a Data seasonally restricted to June-November at all stations. soo x jt 70 " sENE CATCH OF ATLANTho 48LVERSCE c3 a ma rmoo j
' so -
O a wa rm [ goo. !gi h -- . .s ., E ,oo. l j h ao-h s
' ,l i ,'s b- -
5 i i s - too - g g y f 's s- % , W 20 - a
~
N to - g ' 'j s s 7 o o E mm s'i E E s'4 a's s's s'7 s's E e'o e's s'2 . ao .o40 so.ao ' so.ioo ' ioatso ' .120
#0" WP SENE CATCH OF INLAND $1LVERSCE 70 -
.o - - ,
f ,, h so-k zoo-h fs y 30 - 5 i s 2o - too - f
\
\ ~- d
/
g es so - g --
' ? g s't --b 5 s'4 a's s's s'7 a's s's s'o e's-5 = so 4o4o so4o ' so.ioo ' sosiao ' .iPo 40* GN 70 -
60 -
. :Do - - INLAe sitvtRs et M
o 40 - - E 200 - h "" - ioo . g 20 - ,
'q , ___ ,
- - io -
o , , '7' , , , ,W, 0- , ' , , , ,h si .2 n u as .7 so ei .2 <a *a e so Sim 2* 120 120 , YEAR umm i Fig. 7. The annual A<nean catch (no130 m) for the Atlantic Fig 8.,siinrside Frequency distribution, by7 20 mm length intervals, for the silverside and mland silverside taken by seine at JC, WP and GN A itse and Wand saverude taken by seine and trawl frocn 1981 through 1990, during two urut (1976 85) and three-unit (1986-92) operational penods and the 1992 93 report year. 124 Monitoring Studies,1993
g hb7 TABLE 13. %e a means catch (noJ0.69 km) and 95% confi-dence interval for grubby collected by traal at selected stadon: The grubby is the fourth most abundant larval during each report year frorn June 1976 through May 1993 (two-taxon entrained, accounting for 4.5% of all larvae unit operational period; 1976-77 through 1985 86; three unit operauonal period: 1986-87 through 1992-93). collected at EN from June 1976 through May 1993. Entrainment estimates ranged from 11 million in Regn p mr 0.910.3 0 120 0.6 0.1 1978 to 124 million in 1988. An estimated 54 19n.78 0.510.1 2.21 n5 1.110.2 million larvae were entrained in 1993, which was in the range of previous estimates. The A-mean larval gy jjijj gjijj jjijj 1980-81 3.811.1 1.110.2 2.110.6 density was low in 1993, but was within the range of lQjj j.5,i g.5 gjigj gjigj historic data (Table 12). Three-unit operational 1983-84 4.1108 1.7 1 0.3 1.720.3 annual A-mean larval densities fluctuated around the 1984 85 5.911.2 1.610.3 0.910.2
. 1985-86 2.310.5 1.4 a 0.3 0.710.1 two-unit average (Fig. 9). The grubby was the 1986-87 7.212.3 1.110.2 0.910.2 seventh-most abundant taxon taken by trawls, account. 1987-88 3.7 i 1.2 1.210.2 1.110.2 1988-89 10.512.3 1.010.1 I .410.3 mg for more than 2% of the catch at all stations over 1989-90 3.612.0 0.4 1 0.1 1.010.3 the past 17 years. The 1992-93 catches were all 1990-91 a.012.0 0.410.1 0.810.2 1991 92 3.410.5 0.510.1 1.010.2 above the two-um,t A-mean average (Table 13; Fig. 1992-93 6.212.0 1.410.3 1.910.3
- 10) and all were within the range of historic values.
- Data seasonally restricted to December-June at IN, and year-TABLE 12. He a mean8 density (na/500 m2) and 95% confi- r und at JC and NR (Jane-May).
dence interval for grubby larvae collected at EN during each s. user m.uNrv report year from June 1976 through May 1993 (two-unit pe=oo reason radonal periW:1976-85: three unit operadonal period:1986- '8- Na Year EN k .. l 1977 4119 E. l 1978 3819 8 e.
- 1979 1980 3617 3817 3 6
*- N --- - -- -
1981 1U71 27 8" 1982 72 113 l' 1983 681 19 !
- y y; , d,, d,. d. da, .:.a d., .c de, d.,
1986 341 10 "C . 1987 2917 , , , l 1981 95135 r . 1989 631 18 $ e. l 1990 3018 e l 1991 241 ti 1 e- 4 1992 581 17 l 1993 3419 s l 8
- e. 7- m l Data St.asonally restnewd to February - May. < - - - ^- ;-=.=wu?.;- - - j-vin ' n',s ' .o'e s ' dea 'd.s 'de, 'dso ' .o'ei ' . ins e.uNf7 a-UNrT ta ., g 1M .= PaMioo PEAtOD g l c soo . b h .. b
!! ,s . ! i e-E 5 h /\f .. l
- g. v ,------- 3 e
~ , -- w
! dn'd='d.i dn'd ' '.,'d 'd.,'d.
, : aspont vaan n, i .7e. . .et. . ,,sa as er se e e2 Fig.10. ne annual (-) a-mean densities (noJ0.69 km) of Fig. 9. De annual (~) o4nean densities (noJ500 m3) of grubby grubby taken by trawl at NR, JC and IN during two unit and larvae at EN during two-unit and three-unit operational periods. three unit operational perioh. He two unit operational period he two-unit operational period (1976-1985) 64nean density is (1976 1985) a-mean density is represented by the flat line represented by the flat line (- ( - . ) which is eatended over the 3-unit operational
) which is catended over the 34mit operational period as a reference level. Period as a reference level.
Fish Ecology 125
. Similar to the larval abundance indices, the three-unit TABt.E 14. ne a-mean density a (no/500 m3) and 95% confi-
, , . , dence interval for tauto eggs and larvae collected at EN during operational annual 4-mean Indices of grubbles taken each repon year from fune 1976 through May 1993 (two urut by trawl fluctuated around the two-unit average (Fig, gati=* Period:1976-85; three-unit operational period:1986-10), The normalized (each period equals 100%) trawl length frequency distributions of grubby were similar , EgS - L^gAE before and after three-unit operation (Fig,11) 1976. 37216 although th'e 1992 93 distribution had higher 1977 36117 frequencies for smaller fish. !$
1980 1,3642 231 2,842 1 623
!!f5 46118 1981 2,647 2 434 83136 1982 2,244 1 434 44121 80 - 1983 2,1141472 33121 U * * " " " * "
1984 2,1571440 . 312 n eo- O sunn = =ico 1985 3,2371 1,073 15112 3F 1986 2,756 1 794 312 y ,- El 8'** 1987 3.011 1 823 2,2691600 713 w n 17110 C
'1968
_I 1989 2,8872 1,000 1517 E 20 - ,
~ 1990 2,060 1 933 33128 1991 1,878 1765 99151 It' io . .
- 1992 1,449 1589 13 14 o
E E . pata seasonally restricted to May 23 - August 20 for eggs and so.?o ri-so ei so ei.too ' toi iio ' .ito . lune - August for larvae. LDdG7H Fig.11. Frequency disuibudon, by 10-mm length intervals, of twrf swrT grubby taken by trawl during two unit (1976-85) and three-unit PE200 ' PEROD 35 2 - EGGS i (1986 92) opendonal periods and the 1992-93 report year. AT EN e Tautog l 2500-g850-v _';--- - --- l The tautog is the second-most abundant egg taxon g ism. l entrained and has accounted for more than 30% of the P ; 8 ,,,, total eggs collected since 1979. Entrainment ranged l from 705 million in 1979 to 4 billion in 1986 and l was estimated at 1,3 billion in 1992 (Table 6). He o , , , , , , ,,,,,,,,,,, n 7e m na s4 m aa e sa 1992 4-mean egg density was the second lowest since sampling began (Table 14). During the four years irs tuivag ; i ATEN ; immediately after three-unit operation began the e '5-annual 4-mean densities of tautog eggs were above l
- the two-unit average, but during the past three years the annual A-mean densides have been declining (Fig, f- "-
g l l 12), Tautog larvae accounted for 2.1% of all fish g ,,, l larvae caught at EN. The 1992 larval densities were P within the range of historic catches (Table 14) but 8 as _ [----- were lower than the two-unit average (Fig.12), Annual A-mean larval densities during the three-unit o , , , , , , ,,,,,,,,,,, operational period had trends which were almost the 7s 7 m a2 s4 ygg
.'u. es m er opposite of the annual trends for egg densities, except 'I for 1992, During the four years immediately after Fig.12. .ne annual (--) a-mean densities (no/500 m5)of .'
three-unit operation began, the annual 6-mean larval tautog eggs and larvae at EN during two-unit and three-unit densities were below the two-unit average, ne 1990 orentimal eriods. P ne two unit operational period (19761985) d'***", d'"'i'Y i8 '* Presented by the flat line ( ..) and 1991 densities were above the two-unit average, ver the 3 t PenGonal penod u a however,1992 density was below the two-unit '[*h"**t[ded g,, average (Fig,12), (NOTE: different vertical scale used for eggs and larvae.) ' 126 Monitoring Studies,1993 - - ~ . . . - _ _. _ _ _
Tautog catches in trawls have always been lffd Aug relatively low. The 1992-93 catch was within the '*- socs .
^*
range of previous catches (Appendix II). Because l f l tautog catches were low and the data contained many zeroes, annual 4-mean could not be calculated. [ ^ -g ll - - - - A - Tautog collected both before and after three-unit E ~~ 'N operation were assigned an age based on their length $ aooo. l acco ding to recent age length work in LIS reported j l by Simpson (1989). Young-of the-year tautog have m- l l accounted for a high propordon of the fish caught l l since three unit operadon began (Fig.13). O i i . . i i i i i i i i i iiii 76 78 So 82 84 to 68 WO 02 R AE
, Q 3 UNR PEROD i a- reo -
o ,oie ,- , l F
!' ~
i E iso. 95o- ' G l g ,o _ _
- 9 i=- :
E to so - A bo l
, n! nn Iln_ na' \/' '
\ 2' a--' ','~~~ a's igis 7 ' i4ogo. ' rogso ' esigao 'soijsa ' gag ,','7, ,'o 'a' Fig.13. Frequency distribution by length (mrn) and age (deter- Fig. 14. De annual (_) A mean densities (noJ500 m3) of imned frorn age-length key of Sam son 1989) for tautog taken by cunner eggs and larvae at EN during two-unit and three-unit trawl during two-unit (1976-8 and three-unit (1986 92) operational penods, he two-unit operational period (1976-1985) operstwnal penods and the 1992-9 report-year.
A-mean density is represented by the flat line ( -) which is extended over the 3-unit operational period as a reference level. Cunner (NOTE: ddferent venical scale used for eggs and larvae.) The A-mean density of cunner eggs in 1992 was the second lowest in the 14 year data series; only the TADtI 15. He A meane density (na500 m )8 and 95% confi-1986 density was lower (Fig.14). Because of the dence interval for cunner eggs and larvae collected at EN and low densities. the 1992 entrainment esumate was the lvae c nected at Na during each .n;cn year in3m June 1976 through May 1993 (two usus operational penod:1976-85; three-lowest since the three-unit operadonal period began, unit operatimal period:1986-93). The A mean densities of larvae were also low but LGGS LARVAE were within the range of previous values (Table 15). Ye a r EN EN The 1992 A-mean densities of both eggs and larvae 1976 291 14 were below the two-unit operational A mean because 1977 582 28 of these low densities (Fig.14). Most (5 of 7 years) jyj 5.870 2 1.301 13N of the annual three unit operational A mean indices 1980 8.223 1 1.645 581 19 i were below the two-tmit average (Fig.14). 08j [jjj i882,,3 j81l6 The trawl catch of cunner has been declining siuCe 1983 7.0681 2,679 49126 1979 (NUSCO 1993). His trend continued at IN and jyj {701yjj 3ji2 9 JC and the 1992 catch at these two stadons was 1986 2.9692 1.082 521 below the two-unit operational 4 mean (Table 16; Fig.15). The A mean catch at NB was above the l$ 1989 [yi,jj56 '4 N 6.904A 3.077 141 12 two-unit operadonal 4-mean. His was the first time 990 l99 g [y gj7
- f. since three units began operating that any annual A- 1992 4.4161 2.238 814
[ means were above the two-unit operational A-mean ( (Fig.15). To determine an age-frequency distribu- a o,ta ,casonauy nstricted to May 22 - July 23 for eggs, and f tion, ages were assigned based on an age-length key June August for larvae. I Fish Ecology 127
i TAlltI 16. %c A.mean catch s (noJO 69 km) and 95'4, confi- provided by Serchuk (1972). A normalir.ed frequency distribution was calculated for both the two and three-Nn'sYEh"1 period:1976 unit operanons y 85;*Uu*rni*u'n'e three. unit - operai onal unit19Y6 periodsihYh and theayY9931992 93 report I?o'.year. The pene198643). distributions for these three periods appeared quite Yen IN JC NB djfferent and over 50% of the cunner caught during 1776- ' 26.04 19.0 4.012.0 1.0 170 three-unft operation were young-of the-year (Fig.16), , 1977 24.02 23.0 3.0 i 1.0 1.0 g 0 6 1978 6.023.7 3.0 i 1.4 0.710.3 "- 1979 29.01 23.0 9015.0 2.011.0 - 1980 23.0116.0 6.012.0 3.0t 1.2 88 a uninse 1981 12.0t 10.0 5.012.2 3.0 19 0 so - g,..,y,,,,,,, 1982 5.013.0 4012.0 2.01a9 y 1983 3.0t 1.3 40120 10106 ao - e ei ** I984 2.011.0 2.011.0 0.4 i a2 1985 1.0 160 1.010.5 0.4 270 so . 1986 0.110.2 0.510.4 0.1201 g , , 1987 0.210.2 0.410.2 0.0ta0 ww. , 1988 0.310.1 3.013.4 0.2101 r - 1989. 0.920.4 0.81 a4 0.2 220 It' ,, ,, " 1990 0.410.1 0.910.2 0.11 a l . fl - 11 0.4 0 2.3107 0.0 10 0 OE Om llE - 1991 n 1992 1.011 0.7 1.410.5 3.811.0 d g ,,,1 7,,, ,, i , , ,, un y ,,, , 3 7,.gon i i
.g AGE O 1 II Al IV AV
- Data seasonally restricted to May August at IN, May-Sepember at JC, and April. November at NB. Fig.16. Frequency distribution by length (mm) and age (deter-maned fran age length key of Serchuk 1972) for cunner taken try mrt trawl denna two-unit (1976-85) and three-unit (1986 92) opera.
panico ,s.ueer anion tional periods and the 1992 93 report year.-
- n. :
( ao. ! Entrainment mortality studies t u. ! D ,, :--------- Fish eggs entrained through the MNPS cooling-0 j
" Y water system are at risk of suffering high mortality
. because ~ they are exposed to elevated. water e; i 4 , ; , ; . ; ?; . 47;is . temperatures, mechanical stresses and intermittent chlorination. Mortality caused by entrainment could .
"~
; cffect local fish stocks because early life mortality ,
; j rates influence adult abundance (Cushing and llarris' >
g "- : 1973; Cushing 1974;. DeAngelis et al.1977), Because over 85% of the eggs entrained at MNPS
.g "*- l
- were wrasse (tautog and cunner) eggs, studies were 3
- a. A. i.,__,,,,,_,., conducted in 1990,1991 and 1993 to determine the. l
,]" ," , " , " , """" j7&C, entrainment mortality of wrasse eggs. Results of.
entrainment mortality studies conducted in 1990 and
" - '*- 1991 (NUSCO 1991,1992) indicated that the wrasse
"- : egg natural hatching rates and entrainment survival g
f m-
,a .
j
. were higher than previously believed (NUSCO 1992).
However in 1991 a comparison of wmsse abundance - D , , , : at EN and QC (located at the second Millstone quarry _ 3 :
*~ cut, see Fig. 2 in the introduction section) indicated
_. . !___,_ .,_,x that about 56% fewer eggs were collected at QC, 4 A ; 4'ar 4A i; This information lead us to believe that wrasse eggs
^a that suffered entrainment mortality died and settled out Fig.15. He annual (-) 4 mean densities (no./0.69 km) of of the water column and were not Avallable for capture
$r""e*N*" ra# ti IE*i'llNs'.Prhei furui * 'EonaN rat n"j at QC, This would result in a disproportionate (1976 198 A mean density is represented y the fla line number of eggs Collected _ at QC hatching, thus
( _ ) mhich is catended over the 3-unit operational period as a reference level. producing an artificially low mortality rate, ..To , 128 Monitoring Studies,1993 i j
correct for this problem, samples were collected at Since there was such a large difference between the station EN during 1993 using the Pitot tube sampler. abundances of wrasse eggs collected during the day Average wrasse egg hatching rates at EN decreased to and at night, three 24. hour studies were conducted to 4% in 1993 compared to 41% for 1990 and 1991 investigate daily fluctuations in abundance. Samples (Fig.17). Some of this decreased hatching may have collected every 2 hours for a 24. hour period showed been due to sampling, since the averq;e hatching rate very inconsistent results in the three 24. hour studies for eggs collected using the Pitot tube sampler at IN (Fig.18). Based on the 24.hout geometric means, were only 59% while previously calculated hatching the average daily abundances were different but their rates using the bongo sampler averaged 91%. 95% confidence intervals overbpped (Table 17). In Because of these discrepancies,entrainment mortality general, abundances were lower prior to midnight and of wrasse eggs will be assumed to be 100% until remained reasonably constant until late aftemoon. A more reliable estimates can be obtained. rapid increase in abundance occurred in the evening 1990 1991 1993 too - -. 100 - too-
~ ~
d no - - so - so - - I" d so - ~ so - so - -
'- ~ ~
40 - ao - _ 4a - y n- n- n-o " " ^ " STAT ON W OC ' N OC ' N OC ' 'N OC 'o IN OC ' IN OC ' M OC ' IN OC ' N OC ' o IN EN W EN IN EN ' N IN TEST toque t s.Jul 23 Jul AVERAGE 174un 1.JJ 0-JJ 24JJ AVERAGE 21-22-Jun 224wi 2s 2IkJun AVERAGE Fig.17. Hatching rate of wrasse (Lautos and cunner) eggs collected before (IN) and after (QC or EN) passing through MNPS during entrainment mortahsy studies conducted in 1990,1991 and 1993, 1.0. CUNNER . 1.0 - TAUTOO u9 . \ ,' ', , p'g o.e l ,.'\.',, o.e :
..... s % is ,'l , '\
o6- , _ , , _ , gyn
*', o65 ', ,
ho42 a -
/.
!,I '\, ,
ho42 'J.,. . , 6,g. a ,
/',
^ j j'
n, jl, ***~ n, ; ', s' Y '*l
\, f
..,1 c.0 ,
Q. : m ' : . .J. . . . : .
, , , , , , , , , , , , 0.0 , , , , , , ,,,,,
# 4 8 8 s# 12 14 64 18 20 22 24 2 4 6 4 to 12 14 16 18 20 22 24 iME Qanr1 TWE (24ht) 2o000 - - so suco - - so
.r-
~
1s000 2
- do { - do {
, troco-. - so g E 5,ex- - so g N
W W sooo -
- g. : 1 ,J a
g- -,J g 420 l c\ - to $ toon .
~~*
- to !
o
, , , , ,i,I, , , ,1, _l i 0 o l
_ , ,., , , , , , , , i l . o 2 4 s a to 12 14 1s is to 22 24 2 4 e e to 12 14 to to 20 22 24 TIME #4hr) TSAE #4ht) Fig.18. Daily proportional abundance (top)(sample densityhnaximum samples density for each study) of cunner and tautog eggs for the three 24 hour studies at station EN and the geometnc mean density of the three 24-hour studies combmed (bottom) compared to frequency of sampling (percent in 2 hour increments) for entrainment collections taken during June through August from 1983 through 1992. Fish Ecology 129
TABLE 17 Geometric mean (no, per 500 m3 and 95% confi- C0dtlSIOnS dence intervals (CI) for cunner and tautog eggs collected at station EN daring ihree 24-hour studies in 1993 Abundance estimates were calculated for various life one c-er tvs* cn Te <9s% cn stages of fish in the victmty of MNPS to help assess kne s-9 1.345 (562-3,216) 386 (205 725) the effects of station operations. Impacts hae 15-16 4,671 (2,343 9.314) 1,167 (547-2,491) (entrainment, impingement and thermal changes) hly 19-20 4,120 (2.596-6,540) 2,639 (I,871 3.723) quantifying the long term effects of these impacts is far more difficult. The numbers of fish eggs and followed by an even faster decrease, suggesting a larvae entrained through the MNPS cooling-water short daily period of spawning for both cunner and system have been reliably estimated. How this loss tautog. The timing of peak -bundance could not be actually affects local populations is influenced by related to tidal stage, because sampling for the June 8- many mechanisms such as compensatory mortality, 9 and June IS 16 studies occurred during opposite density-dependent growth, fecundity of individual tidal stages. Examination of the geometric mean for species, age structure of the population and life each 2-bour sampling period for the sampling dates history strategies. Impingement of fish at the MNPS mtakes can also be measured but, as in the case of combined showed that, on the average, daily peak spawning for cunner and tautog occurred at about eggs and larvae, the implications of removing these 1800 hours (Fig.18). The rapid decline in abundance juvenile and adult fish from local populations are from 1800 hours to 2400 hours for cunner and to difficult to ascertain. In addition to impingement,
.2200 hours for tautog cannot be attributed to hatching fish populations are also affected by natural and sinca egg incubation takes longer than a day. {ishing mortality and, furthermore, fish that only Herefore, this decline could be caused by high natural inhabit the area seasonally can be greatly affected by mortality, such as predation, suggested by Williams events that occur outside the MNPS area. Changes in et al. (1973). Estimated mortality during this rapid the thermal regime oflocal watus are easy to measure decline period was 44% per hour for cunner and 47% and are well-documented. If water temperatures exceed per hour for tautog. Very little mortality apparently the fish's tolerance levels, they can move out of the occurs during the remaining of the 24-hour period. area. He loss of available habitat may alter local Rese high egg mortality rates may account for the Populations, especially if the area the fish vacates is a low number of cunner and tautog larvae collected rnajor spawning or nursery ground. Trawl, seine and compared to the large number of eggs. ichthyoplankton monitoring programs have success.
Because of the daily cycle in wrasse egg abundance, fully measured impacts from MNPS on local fish the time of day when entrainment samples were Populations, provided a good basis for identifytng collected was examined to determine if it could have which taxa could be potentially impacted, as well as resulted in biased estimates of average daily I ng-term abundance trends which can be used to abundance. The period examined was 1983-92,during assess changes in local populations. the months when wrasse eggs were abundant (June Six species (American sand lance, anchovies, through August). The collection frequency distribu. grubby, silversides, tautog and cunner) have been tions were grouped into the 2 hour intervals used for identified as having the potential to be impacted by the 24-hour studies. The geometric mean density of MNPS, either by entrainment or by exposure to all samples collected during the three 24 hour studies elevated seawater temperatures. Annual abundance - was 2,958 per 500 m3 (95% Cl of 1,971-4,440) for estimates, length, and age based on length were ' cunner and 1,059 (705 1,591) for tautog. The analyzed to detennine if changes have occurred during geometric mean density weighted by the historical MNPS operation. Downward abundance trends were sampling frequency distribution using the 2 hour found for some life stages in four (American sand average abundance was 2,974 for cunner and 1,000 for lance and anchovy larvae, and cunner and tautog tautog. He similarity between these two abundance adults) of the six species. Both American sand lance - estimates for both cunner and tautog suggested that and bay anchovy inhabit the area for short periods of the data used for estimating annual entrainment had time, exhibit large year to year fluctuations, and are not been biased by the daily cycle of wrasse egg Probably more affected by events elsewhere. Cunner m and tautog adults have declined in trawl catches 130 Monitoring Studies,1993
concurrently with a shift to juveniles accounting for a Northeast Utilities Service Company (NUSCO), high proportion of the catch. Entrainment of cunner 1988. Delta distribution. Pages 311320 in and tautog eggs was identified as the primary Monitoring the marine environment of long potential impact to these fish because more than 85% Island Sound at Millstone Nuclear Power Station, of the eggs entrained at MNPS were of these two Waterford,Ct. Ann.Rpt,1987, species. Studies conducted in 1993 suggested that the NUSCO. 1990. Fish ecology. Pages 81118 in mortality of these entrained eggs was over 90%. The Monitoring the marine environment of Long shift in age structure from older to younger could not Island Sound at Millstone Nuclear Power Station, be attributed to entrainment, because entrainment loss Waterford, Ct. Ann. Rpt,1989. would be expected to shift the age distribution NUSCO. 1991. Fish ecology. Pages 89125 in towards larger, older fish because of the loss of new Monitoring the marine environment of Long recruits. Island Sound at Millstone Nuclear Power Station, Waterford, Ct. Arm. Rpt,1990. NUSCO. 1992. Fish ecology. - Pages 111156 in References Cited Monitoring the marine environment of Long Island Sound at Millstone Nuclear Power Station,- Botelho, V.M., and G.T. Donnelly 1978. A statisti- Waterford, Ct. Ann. Rpt,1991. cal analysis of the performance of the Bourne NUSCO.1993. Fish ecology. Pages 153180 in plankton splitter, based on test observations. Monitoring the marine environment of Long NMFS unpub. ms. Island Sound at Millstone Nuclear Power Station, Cushing, D.H. 1974. The possible density- Waterford, Ct. Ann. Rpt,1992. dependence of larval mortality and adult mortality Pennington, M.1983. Efficient estimators of abun-in fishes. Pages 103-111 in J.H.S. Blaxter, ed. dance for fish plankton surveys. Biometrics The early life history of fish. Springer Verlag, 39:281 286. New York. Pennington, M.1986. Some statistical techniques Cushing, D.H and J.G.K. Harris.1973. Stock and for estimating abundance indices from trawl recruitment and the problem of density dependen- surveys. Fish. Bull., U.S. 84:519-525. ce. Rapp. P.-v. Cons int. Explot. Mer SAS Institute, Inc. 1985. SAS user's guide: 164:142 155. Statistics. Version 5 ed. SAS Institute Inc. DeAngelis, D.L., S.W. Christensen, and A.G. Clark. Cary N.C. 956 pp. 1977. Response of a fish population model to Serchuk F.M. 1972. The ecology of the cunner, young-of-the-year mortality. Oak Ridge Nat Lab. Tautogotabrus adspersus (Walbaum) (Pisces: Publ. No.1065. Labridae), in the Weweantic River Estuary, Draper, N., and H. Smith.1981. Applied regression Wareham, Massachusetts. M.S. Thesis, Univ, analysis. John Wiley and Sons, New York 709pp. Massachusetts, Amherst, MA.111 pp. Hennemuth, R.C., J.E. Palmer, and B.E. Brown, Simpson, D.G.1989. Population dynamics of the 1980. A statistical description of recruitment in tautog, Tautoga onitis, in Long Island Sound. i eighteen selected fish stocks. J. Northwest Atl. M.S. Thesis, So. Conn. State Univ., New Haven, Fish.1:101 111. Ct. 65 pp. l Leak, J.C., and E.D. Houde. 1987. Cohort growth Williams, G.C.1967. Identification and seasonal I and survival of bay anchovy, Anchoa mitchelli, size changes of eggs of the labrid fishes, l
!arvae in Biscayne Bay, Florida. Mar. Ecol. Tautogolabrusadspersus and Tautog onitis, of I 37:109 122. Long Island Sound. Copeia 1967:452-453.
McHugh, J. L 1977. Fisheries and fishery resources Williams, G.C., D.C. Williams, and RJ. Miller. of New York Bight. NOAA Tech. Rep. NMFS 1973. Mortality rates of planktonic eggs of the q Cire. 401. 51 pp. cunner, Tautogolabrus adspersus (Walbaum), in Monteleone, D. M., W.T. Peterson, and G.C. Wil. Long Island Sound. Pages 181 195 in A. Pacheco, llams. 1987. Interannual fluctuations in the ed. Proceeding of a workshop on egg, larval and ; density of sand lance, Ammodytes americanus, juvenile stages of fish in Atlantic Coast estuaries. larvae in Long Island Sound, 1951 1983. Nat. Mar. Fish. Ser., Middle Atl. Coast. Fish. Estuaries 10, 246-254. Ctr. Tech. Publ. No.1. Fish Ecology 131
i 1
)
1 l l l
. APPEliDIX L List of fishes edlected in the Hsh Ecology sampling programs. i Scientific rame Common rume Trawl Seine Ichthyoplankton l
Acipenser oxyrhynchus Atlantic sturgeon
- Nosa serrivalis . blueback herring *
- Nova medweris hickory shad * ~,
Alara psessioharenge elewite * * * ' Alcas aspidassima American shad *
- Noseapp, river herring * * *
.l Nurerw scAoepf orange filefish
- Ammatyses americanur American sand lance * * * \
Anchos Arpsetur striped anchovy
- Anthoc miscAilli bay anchovy * *
- l Angmilla rarrafa American eel * *
- Apeltas quadracus fourspine stickleback * *
- Bairdiella eArysoura sUver perch * '
Bravoortia tyrannus Atinntic menhaden * *
- Brasma brosma cusk
- Corou crysos blue runner *
- Carau Airpos crevalle jack *
- Centropresh striata black sea bass *
- Chaetondai oceflatu spotfin bouerilyfish *
- Clupcidae herrings *
- Clapea Aarengar Atlantic herring * *
- Conger oceanicus conger cel *
- Cyclopterus lumpur lumpfish *
- Cynarcion regalis weakfish * *
- Cyprinalon wariegatu sheepshead minnow *
- Dactylopterar voluaar flying gumard
- Daryath centrours soughtail stingray
- Decapterns macarellus mackerel scad
- Enckelppus cimbriar fourbeard rockling *
- Erropus microssomus smallmouth flounder *
- Eucinossomur lefroyi mouled mojarra
- Thtularia tabacaria bluespoued cometfish
- Fanfular diaphanar banded killifish
- Fundular heteroclitus mummichog *
- Fundularluciae - spotfinkillifish
- Fundular majalir striped kilhfish
- Gadadae codfishes *
- Gadur morAas Atlantic cod *
- i Casserosseur aculeatus ihreespine stickleback * * *
- Gasterosseus wheatlandi blacksponed stickleback * *
- Godiidae gobies *
- Gobiosoma parburgi seaboard goby
- Hemitripterur americanut ses saven *
- Hippocampus erocra lined seahorse *
- Labridae wrasses
- Lacsophrys spp, boaftsh
- Isiostanur mantAurus spcs *
' Lipyh rm seamall *
- Lophius americanus goosefish *
- Imania parws rainwater killifish *
- Macrosoarces americanus ocean pout
- Melanogennymur meglefinus haddock
- Monticirrhus samaritir northem kingfish * *
- Manidia aeryllina inland suverside *
- Menidia menidia Atlantic suverside * *
- Merluccin bilinearir 'sUver hake * *
- l MicrogaAs amicod Atlantic tarncod *
- j Monacanthur Ahpidus planchead filefish
- MonocentAus spp. fuerish
- i 1
132 Monitoring Studies,1993 i i
1 APPENDIX L (continued). ] Scientific name Canmon name Trs*1 Seine Ichthyoplankton Morone americana white perch *
- j Morone saaatils striped bass *
- Mugilcephalur striped snuHet * *
- Mksil curama white mullet Mullusawatur ' red goatfish
- Murrels cana smooth dog 5sh
- i Myliobatisfeminvillel bullnone rey *
]
Myozocephalar senatur grubby * *
- Myozocephaist octodecomrpinosus longham sculpin *
- Myozocephalus spp, actdpin Ophidiidae cusk <els
- Ophidion marginatum striped cusk<cl * *
- Ophidion welski crested cusk sel
- Op.manut saw oyster toadfish
- Osmerar morda.t rainbow smek * *
- Paralichthyr dentatus summer flounder *
- Paralichthys oblongus fourspot flounder *
- Papritur triacanthat butterfish * *
- Pholk gunnellus rock gurusel * *
- Pleuronectes americanst winter flounder * *
- Pleuronectesferruginess yeDostail flounder *
- Pollachius vivent poDock *
- Pomatomus saltatrh bluefish *
- Priacanthur arenatus bigeye
- Priacanthus cruentatar glasseye snapper
- Pristigenys alta short bigeye
- Prionotar carolinut northem searobin * *
- Prionorar evolans striped searobin * *
- Pungitius pungitiur ninespine stickleback . * *
- Raja eglanteria cleamose skate
- Raja trinacea litde skare * '
Raja ocellata winter skate
- Salmo trutta brown trout
- Scimenidae drums
- Scophthalmur aguosar windowpane * *
- Scomber scombrar Atlantic mackcrel *
- Scyliorhinar retVer chain dogfish
- Sabr crumenorthalmne bigeye scad
- Selene setapinnh Atlantic moonfish
- Selene vomer looLdown *
- Synodurfoetens inshore lizardfish
- Sphyraena borealu northem sennet
- Sphoeroides maculatus northem puffer * *
- Squalar acanthias spiny dogfish
- Stenotomus chrysopt scup *
- Strongylura nurina Atlantic needlefish
- Syngnarhusfuscus northern gipefisb * *
- Taurogobbrus adrpersar cunner * *
- Tautoga onith . tautog * *
- Trachinorarfalcarar permit *
- Trachurus141k mi rough scad
- Trachinocephalar myops snakef1sh
- Trinectes maculatus hogchoker
- Ulvaria subb(urcata radiated shanny *
- Upeneur parvur dwarf gostfish
- Urophyck chuss red hnke * *
. Urophych tenuis white hake *
- Urophycis spp, hake * *
- Fish Ecology 133
APPENDIX IL Total number of samples collected and number of fish caught by trawl for each report year (two-unit operadonal period;197671 through 1985 86, thru-unit operadonal penod:1986 87 through 1992-93).
. Year 76-77 77 78 78-79 79 80 80-81 81-82 82 83 $3 84 84-85 85-86 86-87 87 88 88-89 89-90 90-91 91-92 92-93 Number of samples 468 468 468 468 468 467 474 480 468 468 468 465 468 468 468 468 468 loxon
- P. americanus 7,415 6,045 7,236 11,442 13,296 10,749 19,201 12,5fo 13,260 9,849 9.321 8,877 13,440 8,690 9,378 8,511 9,828 S. cArywps 1,918 4,040 2,556 4,094 3,844 3,403 4.8 % 5.268 4,206 2,640 5,205 3,632 3,294 2,869 10,497 25,287 9,710 S. aquarar 1,480 1,296 875 1,508 2,016 1,518 3.517 2,475 2,199 2,483 1,655 1,966 2,399 2,735 1,656 876 1,519 Raja s;p. 661 579 362 402 954 696 2,797 2,493 1,583 3,801 2,207 2,183 2,864 2,437 2.858 2,872 1,892 Anchoa spp. 979 580 2,226 16 109 578 38 109 157 10,003 8.038 292 496 1,241 31 1,557 80 Manidua spp. 2,152 1,647 1,463 1,340 882 501 518 583 322 519 3,438 698 982 4&5 474 1,346 3,567 M. aenasar 266 636 297 342 632 870 9% 672 477 341 727 434 989 615 640 451 857 Gadidae 112 326 230 211 3,296 1,424 476 481 562 630 168 593 88 84 121 106 207 T, adrpersu 838 875 400 1,309 940 840 611 362 248 119 - 147 63 205 IM ;03 141 401 Prionaar spp. 338 322 138 313 405 (61 1,059 422 371 395 436 159 356 1.277 363 435 327 P. triacanthe 37 44 407 174 44 69 182 244 19 135 132 Ill 1,831 179 1,878 ' 426 1,302 P. dentatur 286 141 92 75 122 240 250 269 1,937 281 653 617 360 80 393 403 634 Urophyen app. 99 87 103 69 163 313 615 286 251 272 286 164 174 . 141 335 91 9M M. bilmearu 425 163 69 134 558 220 382 147 100 175 197 118 73 321 124 179 337 G. aculaatar 30 12 47 77 206 103 63 218 1102 116 354 405 94 10 15 447 172 E. microstomus 43 7 0 3 31 91 94 56 85 218 640 190 359 62 492 394 694
- T. onus 229 283 263 270 146 228 239 140 119 134 215 87 162 85 185 111 131 P.gunnettas 85 106 99 65 251 273 302 145 127 151 186 203 407 189 155 126 152 Sfascus 43 54 49 88 151 264 232 202 254 196 2M 275 321 85 154 134 175 O. mordaz I11 286 90 5 123 63 89 26 227 391 257 249 152 26 48 35 334 H. enericanar 34 48 39 148 278 410 557 377 125 41 45 11 3 7 12 38 1 A. guadracus 10 6 24 27 194 765 76 11 112 130 1W 52 31 11 18 100 69 B. tyrannar i 14 11 I i 1 0 1 0 34 10 4 1 1,320 5 205 M C. striata 33 9 3 4 10 63 23 38 30 80 412 16 53 69 130 94 60 P. oblonsar 31 7 21 11 51 32 138 34 81 66 72 28 123 155 92 28 55 M. octodecemrpinasar 11 10 97 40 30 145 172 51 20 13 12 5 12 18 56 222 9 A. pseudoAaragus !! 272 13 17 4 15 5 26 4 16 208 1 4 3 14 41 35
- 0. rau 98 21 7 18 31 35 25 23 24 32 56 51 58 30 55 17 5 A. americanar 5 59 128 36 117 14 19 11 19 6 11 29 1 1 1 1 2' A rartrata 19 16 8 5 10 37 29 24 22 34 28 22 20 5 15 8 2 C. lumpar 19 11 28 58 11 0 14 1 29 1 1 44 6 1 7 6 21 C. regalu 9 21 4 2 2 45 7 0 1 5 36 5 14 9 6 1 5 Lipars om 9 27 10 10 18 33 15 16 11 3 18 8 12 22 2 3 22 S. maculaiar 16 10 1 0 9 14 16 15 7 7 3 1 9 14 26 50 26 A sapidarima 33 6 1 5 40 12 0 29 0 0 1 1 9 5 3 7 1 r
C. Aurangar i 9 13 0 0 1 0 2 9 63 10 2 1 2 1 10 19 Alasa spp 0 0 0 0 0 0 0 0 0 0 0 4 11 26 26 34 52 Clupeidae 2 1 0 0 0 0 0 0 0 110 0 0 0 0 0 0 0 M. cons 2 5 45 11 1 5 4 6 0 2 2 1 2 2 4 2 0 Hippocamput ereciar 0 0 0 0 0 0 0 1 4 7 20 12 6 4 17 67 4 f.frrruginar 7 5 5 2 3 15 6 0 4 0 0 23 0 3 0 3 0 M. Anpidar 3 6 8 4 0 0 8 I 8 9 2 2 2 11 9 5 1
- 4. assinald 3 11 8 12 4 1 1 17 5 2 4 2 2 0 0 10 4 Gobudae 3 0 0 0 4 0 0 3 9 7 2 5 10 2 23 17 1 N. amaricana 8 17 3 5 8 2 1 0 0 0 0 0 5 11 0 3 3 F. sabacaria 2 3 0 0 3 0 1 0 8 1 2 0 1 3 22 9 5 M. americanar 5 7 9 2 2 2 2 2 3 1 0 6 2 2 0 10 1 S. setapinnis 0 0 0 0 0 0 0 0 1 0 0 0 30 0 0 0 1 A schospfi 0 2 2 1 1 0 0 1 1 2 2 0 3 4 6 1 1 D. volitan.: 3 0 0 0 0 I 3 1 0 1 3 4 1 2 4 3 3 L aanthurar 5 6 0 0 0 0 2 0 0 3 1 0 5 0 0 0 0
- 0. marginatum 0 0 0 0 0 0 0 0 1 2 4 4 4 0 4 3 2 P. cr uentatus 0 0 0 0 0 1 0 2 3 1 1 1 1 0 0 0 0 P. sahatrir 1 1 0 2 1 2 3 3 0 0 0 2 1 0 1 11 .0-Hea. saxatdi.r 0 1 0 1 0 3 1 0 0 0 4 2 1 4 3 0 1 S. vomer i 2 0 0 0 0 0 0 0 0 1 1 11 1 0 0 0 I
134 Monitoring Studies,1993 I J
. . . - - - - - ~ . ~. .- . . . _ . . .. . . . . ,
APPENDIX II (condnuedh Year 76-77 77J/8 78 79 79 80 80-81 8142 82 83 83 84 84-85 8546 b6-87 8748 8849 89-90 90-91 91 92 92-93 Texcai *
- r. pungitim 0 0 0 0 1 2 0 0 5 5 0 0 0 0 1 0 0 Casterosteidae 0 0 0 13 0 0 0 0 0 0 0 0 0 0 0 0' O Fwidutus spp. 0 0 0 0 0 5 2 0 0 2 0 0 0 1 1 0 0 L americanus 2 0 0 0 1 0 1 0 0 0 0 U. subbywcata 0 1 1 4 2' 3 0 2 0 0 1 1 0 0 0 1 1 1 4 0 1 2 3 Mor, saratdir 0 0 2 0 0 0 1 1 1 1 0 0 0 0 0 0 0 5.borealu o 0 0 0 0 0 0 2 0 6- 0 0 1 1 1 0 0 S.forsvar 0 1 4 0 0 3 1 0 0 0 0 0 0 0 0 0 0-C. oceanicus 1 0 0 0 0 0 0 2 0 Af. awasus 0 1 1 1 1 3 0 1 1 0 1 0 0 0 2 0 0 0 0 4 0 0 0
- r. arenatw 0 1 I 0 0 0 0 0 0 0 2 0 0 0 T. lashami 0 1 1 3 1 0 0 0 4 0 0 0 0 0 0 0 0 4 0 0 0. O T. macul.2tus 3 1 0 0 0 0 0 0 0 1 2 1 0 0 0 0 0 C. ocellatw 0 0 0 0 0 0 0 0 G. wAsailandi 0 0 4 1 1 1 I 1 0 3 0. O !
0 0 1 1 1 0 1 2 0 1 0 0 1 1 loctophrys spp. 0 0 0 0 0 0 0 0 3 0 0 0 0 0
- f. alla 0 0 0 3 'O
, 0 0 0 1 0 0 2 1 1 0 0 0 0 0 'O C. crysos 0 0 0 C 0 0 1 1 1 2 0 0 0 0 0 0 0 C. lWppar 0 0 0 0 0 0 0 0 1 1 0 0 0 2 0 0 0 E. cimbriw 0 0 0 0 0 1 0 0 0 0 Af. capA,2lus 1 1 1 0 0 1 3 0 0 0 0 0 0 0 0 2 L parva 0 0 1 0' O O 2 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0
- 5. scombrus 0 1 0 1 0 0 0 0 0 0 0 0 0 1 0 1 0 S.acan Aias 0 0 0 0 0 0 1 0 I O O O O O O 4 0 A. mediocris 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 C. varissatus 0 0 0 0 0 0 0 0 0 0 0 0 -1 D. macarellar 1 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 Afasslafinar 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0~ 0 0 A. exyrhync Aus 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 A. maculatus 1 0 0 0 0 0 0 0 0 0 0 0 B.chrysoura 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 B. brarms 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0' O D, cassrova O 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Monacanthus spp. 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0- 0 0 1 Af.framinvdtsi 0 0 0 0 0 0 1 0 0 -0 0 0 0 0 0 0 Afyozocephalus spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 O 0 0 0 1 0 0 S srutta phidddae 0 0 0 0 0 0 O I O O O O O O 0 0 0 0 1 0 0- 0 0 0 0 0 0 0 0 0
0 0 S. retifer 1 0 0 0 0 0 .0 0 0 0 0 0 0 0 0 0
- 5. crumssopth. Imus 0 0 0 0 0 0 0 0 0 0 0
- 5. naria:
1 0 0 0 0' O. 0 0 0 0 0 0 0 0 0 0 0 0 0 -0 T. myops 0 1 0 0 < 0 0 0 0 0 0 0 0 0 0 0 0 0 f 0 0 1 0 '0 T fakarus 0 0 0 0 0 0 0 0 0 0 0 0 U. parvar 0 0 1 0 0 0 0 0 0 0 0 0 1 0 0 0 .0 0 3 0 local 17,941 18,147.17,497 22,469 29.010 24,T!3 37,699 27,860 28,169 33,546 35,566 21,674 29,529 23,47130,473 44,957 33,768
- Fish idendfied to the lowest pracdcal tanait 5
i Fish Ecology 135 1 I
APPENDIX III. Total number of samples collected and number of fish caught by trawl at each station Gune 1976-May 1993). Stauco JC NR NB TT BR IN TOTAL Number of samples: 1,328 1,327 1.329 1,329 1,329 1,329 7,502 Taxon
- P, americanar 15,247 66,574 21,665 25,605 21,506 28,501 179,098 S. chrysops 9,030 566 34,6 % 15,751 10,101 27,215 97,359 5.aguarar 1,701 3,315 2,823 4,258 14,327 5,749 32,173 Raja spp. 1,867 39 4.918 8,296 11,985 4,536 31,641 Aachoa spp. 3,342 1,177 18,223 339 20 3,429 26,530 Menidia spp. 4,529 6,356 2,176 1,644 457 5,755 20,917.
M. seaasus 1,375 5,040 557 590 860 1,820 10,242 Gadidae 2,084 834 2.840 1,039 279 2,039 9,115 Prionoteip I18 1,013 684 1,341 3,666 955 7,777 T. a hpersar 1,906 386 631 283 527 4,066 7,799 P. dentarar 1,032 1,825 932 1,794 -276 974 6,833 P. triacoathus 73 13 1,001 1854 2,858 1,415 7,214 Urophych spp. 530 82 448 405 2,384 564 4.413 M. bitanors 199 10 532 669 1,558 754 3,722 G. aculeatus 2,076 1,349 17 12 6 11 3,471 T. oaish 745 813 305 206 271 684 3,024 P. gunnellar 1,551 515 322 230 39 365 3,022
- f. micrmsomus 247 35 717 327 1,574 ' 561 3,461 S.fureus 844 1.458 163 100 116 203 2,884
- 0. mord,u 1,421 300 245 174 % 276 2,512 H. americanar 444 82 405 298 540 405 2,174 A. ga2drocar 181 1,557 1 1 1 2 1,743 B. trannus 532 1,056 40 6 1 32 1,673 C. striata 94 212 74 53 74 620 1,127 P. oblongur 0 12 73 12 900 28 1,025 M. ocrodecentplaosur 3 0 20 53 831 16 923 A. pseudoAarsag us 10 67 57 30 274 251 689
- 0. sau 9 565 0 0 0 12 586 A. americaams 20 % 6 19 300 9 460 A. rarrrasa 43 230 0 20 3 8 3 04 C lwyur 161 9 21 8 2 57 258 Lipars 26 11 38 40 97 27 239 S. mac sus 19 101 17 9 18 R) 22?
C. regald 22 1 27 11 77 34 172 A.sapidnsim 8 17 56 12 38 22 153 Hippocampus erecsar 53 63 9 3 2 12 142 C. harangus 69 4 27 12 31 5 148 Clupcidae 0 1 0 1 0 111 113 Alasa spp. 7 31 11 21 73 10 153 M. carus 10 1 40 3 36 4 94 Gobiidae 4 78 2 0 0 2 86 A. sessimlis 1 29 17 11 14 14 86 M. Anpidur 20 2 11 10 22 14 79 P.ferrugiaeum 0 2 0 8 66 0 76 M. ameru:ana 8 23 6 2 6 22 67 M. americanur 0 0 0 1 55 2 58 F, sabacaria 38 13 1 0 0 8 60 S. setapinau 16 0 8 -2 0 6 32 P. salsatru 3 5 6 8 5 1 28 A. scAcepfi 10 0 4 2 4 7 27 D. volitans 2 13 0 0 0 14 29 i L. szathwar 4 0 8 0 4 6 22 -
- 0. marginarum 5 6 2 2 8 1 24 P. cruensaius 2 0 2 5 2 ~8 19 S. vomcr I i 14 0 0 l 17 136 Monitodng Studies,1993
L l APPENDIX III (continued). Stauan JC NR NB Tf HR IN lOTAL Taxon
- Men. saxatJis 1 3 4 5 1 3 17 L. americanus 1 0 2 2 9 1 15 P.pungitic 10 3 0 0 0 1 14 U. subb{urcata 3 0 1 1 1I I I1 Gasterosteidae 2 11 0 0 0 0 13 Fundulw spp. I 11 0 0 0 0 12 C. octonicus 1 4 3 2 2 0 12 Mor. saratar 0 11 0 0 0 0 11 S. borealis 5 6 0 0 0 0 11 S.footens 0 3 0 2- 5 1 11 lociophrys spp. 6 2 0 0 0 1 9 P. arenatur 0 1 1 0 2 5 9 G. wheatlandi 7 2 0 0 0 0 9 M. aurate 1 0 0 l 1 6 9 T. lashami 4 0 3 0 0 1 8 T. macufatw 5 2 0 0 0 1 8 C. acellate 2 2 1 0 0 2 7
- 5. ocantAias 0 0 1 0 6 0 7 P.cha 3 0 0 1 I I 6 C. crysos 0 0 2 0 1 2 5 E cimbrius 2 0 0 0 3 2 7 C. hippas 0 0 0 0 0 4 4 M. esphalus 1 2 1 0 0 0 4 S. scombrus 0 0 1 1 1 1 4
. L. parva 0 0 0 0 3 0 3 A. mediocris 1 0 0 0 1 0 2 C. variegatur 0 1 0 1 0 0 2 D. macareIlus 1 0 1 0 0 0 2 M. aeglefinus 1 0 0 1 0 0 2 A. exyrhynchav 0 0 1 0 0 0 1 A. maculatus 1 0 0 0 0 0 i B. chrysoura 0 0 0 0 1 0 1 B.brarms 0 0 0 1 0 0 1 D. controura 1 0 0 0 0 0 1 Monocanthus app. O I O O O O 1 M.freminvillei 0 0 1 0 0 0 1 Myoxocephale opp. 0 1 0 0 0 0 1 O 0 0 0 0 1 0 P.piududae marinus 0 0 0 1
1 0 0 1 S. #rutta O I O O O O .1. S.resfer 0 1 0 0 0 0 1 S. crwnenopshalmus 0 0 0 1 0 0 1 S. wrina 0 0 0 0 1 0 1 T. mwps 1 0 0 0 0 0- 1 T.fakaius 0 0 0 0 0 0 I fl. parvur 1 0 0 0 0 0 1 Total 51.805 96,057 94,921 65.610 76,451 91,737 476,581 j
- Fish identmed to the los est practical taxcn j i
q 1 Fish Ecology 137
APPENDIX IV. Total nurnber of sarnples collected and nurnber of fish caught by seine for each report year (two unit operational pericxt:1976-77
. through 1985-86; three-unn operational period:1986-87 through 1992 93),
Year 76 77 77 78 78 79 7940 80-81 81 82 82 83 83 84 84 85 85 86 86-87 87-88 88-89 b9 90 90-91 91 92 92-93 I Number of sarnples 66 .72 72 72 72 72 98 120 174 156 156 156 156 180 180 180 13i j l Taxon
- Afsnidia spp. 40,619 18,194 1,335 ' 1,062 7,996 3,186 . 5,413 9,807 1,538 1,375 5,441 8,542 6,107 5,044 11,191 6,596 9,503 rundulutspp. 1,695 1,199 - 815 659 952 613 915 1,081 1,463 906 111 432 3,142 831 859. 1,224 513 A. quadracas 464 603 258 266 49 94 89 1,827 167 106 297 98 152 302 123 1,(T18 55 C. variegatur 48 673 39 30 10 352 146 50 29 28 2 2 21 3 30 1,170 76 i A. amargasus 6 520 16 51 10 318 82 30 21 0 7 1 4 0 47 156 27 !
P.soltatrix 1 0 1 6 0 2 135 4 19 35 12 12 5 6 825 14 0 ..
. B. tyrannus 0 0 17 0 4 0 7 1 0 8 6 6 3 521 2,652 2 I . P.pungitius 5 1 28 2 5 2 10 321 8 11 8 4 30 24 3 6 0 S.furcus 9 3 9 108 6 8 21 12 35 30 33 19 74 11 17 40 11 G. aculeasur 9 154 27 5 3 2 5 53 6 6 19 15 38 8 0 3 0 P. americanur 4 6 4 1 6 5 2 3 17 40 18 17 16 48 9 10 2 (4. caphatur 0 4 3 23 41 1 4 4 1 0 38 4 46 0 0 1 1 ,
A. pseudoharang us 0 0 0 0 0 0 0 1 93 0 0 4 0 6 0 0 0 i Go6dae 2 0 9 2 20 16 11 8 11 11 8- 0 2 2 0 0 1 G. wAnattandi 0 0 0 0 0 8 6 6 19 12 9 22 9 8 0 1 0 Af. curama 0 0 0 0 0 0 0 1 9 0 0 0 43 3 22 1 0 C. harangur 0 0 0 0 0 0 2 0 0 0 30 0 6 1 0 0 0 L. parva 1 2 0 0 0 0 0 2 0 1 0 16 14 2 1 32 7 A rostrata 10 5 12 3 2 0 1 1 0 0 3 0 0 0 0 0 '0 7.fakatus 0 0 1 0 3 0 0 0 0 0 0 0 22 7 0 0 0 Af. asnatur 3 2 1 2 0 0 3 1 3 3 3 2 4 0 0 0 3 , O. mordaz 0 0 0 0 0 0 0 0 0 2 0 0 18 0 0 0 0
. Anchoa spp. 0 0 0 0 2 0 7 2 1 0 0 0 0 0 4 0 0 T. onitir 0 0 0 0 0 0 4 0 0 0 0 0 2 0 7 1 1 A. asstiuslis 2 6 0 0 0 0 0 0 0 0 0 0 0 4 0 0 0 Carrarosteur s;p. 'O O O O O O O O O O 12 0 0 0 0 -0 1 C. Airpar 0 0 1 0 0 1 0 0 0 1 0 0 4 1 3 0 0 $ maculatur 0 0 0 1 0 0 1 0 0 3 3 0 1 0 1 0 0 T. adspersus 0 0 2 0 0 0 3 0 1 0 0 0 0 0 1 0 0 A. sapidissima 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 Afsn sazatilir 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 P. treacanthus 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 P. gunnellus 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 S. aquasus 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 1 0 S. marina 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 1 Clupsida, 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 C. regalir 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 O S.setapinnis 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 S. vomer 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 Prionotur spp. 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 Urophycirspp. 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 Tout 42,881 21,372 2,579 2,221 9,109 4,609 6,869 13,215 3,444 2,582 6,061 9,196 9,763 6,336 13,667 15,012 10,204 Fuh identified to the lowest practical taxon.
t l l 1 1
.I 138 Monitoring Studies,1993
APPENDDC V, Total number of samples collected and number of fish caught by seine at each stance Gune 1976-May 1993). Yeat JC GN WP 'lOTAL Number of samples 693 740 747 2,180 Taxon * - Menidia spp. 99,702 24,200 21,236 145,138 Fudulw spp. 13,413 2,141 1,876 17,430 A.e mdracas 5,992 19 21 6,032 B. tyranna 715 13 2,524 3,252 C. variegata 1,831 845 34 2,710 A. amerranus 4 213 1,080 1,277 ' P.ultatrh 945 50 82 1,071 f.pungitiw 357 102 10 469 S.fucur 94 64 288 446 G. aculeatw 2 71 29 47 353 P. americanur 43 12 154 209 M. cephalar 99 43 29 171 ~i ' A.pseudokarengur 8 % 0 104 Gadidae 66 31 6 103 , G. wheatlandi 36 26 38 100 M. curema 63 14 2 79 L parva 66 7 5 78 Anchoc spp. 16 2 24 42 C. Aarengur 39 0 0 39 A. rastrata 31 2 .4 37 T.fakatur 30 3 0 33 M. senaear 8 13 9 30
- 0. mordas 18 0 2 20 T. cwutir 12 2 1 15 A. aestinath 3 6 3 12 Gasserosteur rpp. 0 1 11 12 C. Airpar 10 0 2 12 S. macul.sts: 0 2 8 10 T. adspersnt 6 1 0 7 5.aquarav 0 0 3 3 A. sapidhrima 0 0 2 2 Men sautilis 1 0 1 2
- f. triscandaar 0 1 1 2
- f. smar//us 0 0 2 2 S. marina 2 0 0 2 Clupeidae 0 1 0 1 C. regata 1 0 0 1 Pri<morar syp. 0 1 0 1 S. setapinnst 0 1 O 1 S. vomer 1 0 0 1 Urophych app. 0 1 0 1 Total 123,890 27,942 27,505 '179,337
- Fhh ideritified to the lowest practical taxon.
Fish Ecology 139 i
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- ._ . . . 4 - - _ , - - . . . - . . . . . - . . . _ . _ . - ,. - . - _ . . , . . , _ . . , , - , . . . . . - - . . . - - -
l l 1 Winter Flounder Studies i l d In trod u c t io n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3 Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 l Samphng programs ........................................... 144 Adult winter flounder sampling .............................. 144 { Larval winter flounder sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 Juvenile winter flounder sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 Indices of abundance ..........................................148 Relative annual abundance of adults ........................... 148 Absolute abundance estimates of adults .........................149 Adult spawning stock size and egg production ....................149 i Development and growth, abundance, and mortality oflarvae .......... 149' l Abundance, growth, and mortality of juveniles in summer ............ 151 i Abundance ofjuveniles during fall and winter . . . . . . . . . . . . . . . . . . . . . 151 Stock and recruitment relationship . . . . . . . . . . . . . . . . . . . . . . . . . .. 151 Assessment of MNPS operation on Niantic River winter flounder . . . . . . . . . . . . 153 ! Estimates oflarval entrainment at MNPS ........................154 Mass-balance calculations ..................................154 1 Stochastic simulation of winter flounder stock dynamics . . . . . . . . . . . .. 156 Results and Discussion ..............................................164 Seawater temperature .......................................... 164 Adult winter flounder .......................................... 164 , Relative annual abundance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 l Absolute abundance estimates ... ...........................167 Spawning stock size and egg production ........................ 171 Larval winter flounder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 Abundance and distribution ......... .......................172 ; Development and growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 - 3 Mortality .............................................183 Juvenile winter flounder ......t................................. 185 l Age-0 juveniles (summer) .................................. 185 Age.0 juveniles (late fall and early winter) ....................... 196 Age-1 juveniles (late winter) ................................198 Comparisons among life-stages of winter flounder year-classes . . . . . . . . . . . . . . 2 00 i Stock-recruitment relationship (SRR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 i MNPS impact assessment ....................................... 207 l Larval entrainment .......................................207 Stochastic simulation of the Niantic River winter flounder stock . . . . . . . . . 214 j Conclusions .....................................................220 References Cited .................................................. 222 l l l WinterFlounder 141 1 l
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l I 142 Monitoring' Studies,1993 .
Winter Flounder Studies Introduction summarized by Klein-MacPhee (1978). Because the early life history of the congeneric European plaice ne winter flounder (Pleuronectes americanus) has (Pleuronectes platessa) has many similarities to that been a focus of environmental impact studies by of the winter flounder, relevant literature was also Nonheast Utilities Service Company (NUSCO) at the reviewed to gain further insights into winter flounder Millstone Nuclear Power Station (MNPS) since 1973. population dynamics. It is an important sport and commercial fish in Con. MNPS operation results in the impingement of necticut (Smith et al.1989) and is an abundant mem- juvenile and adult w!nter flounder on the traveling ber of the local demersal fish community. The winter screens of the cooling-water intakes and the entrain-flounder has been reported from Labrador to Georgia, ment of larvae through the condenser cooling-water but is most abundant in the ccmra! part of its range system. Studies of the winter flounder found near (Scott and Scou 1988), which includes Long Island MNPS staned in 1973 to obtain data needed to assess Sound (LIS). Movement patterns and reproductive power plant effects on the Niantic River stock. Al-activity are seasonally specific and well-documented though knowledge of annual variability is important (e.g., Klein MacPhee 1978). Most adult fish enter for assessing short-term impacts, the most significant estuaries in late fall and early winter and spawn in changes in fisheries tend to occur on longer time upper portions of estuaries during late winter and early scales (Cushing 1977; Steele et al.1980). Therefore, spring. Three years are required for for oocyte matura- the development of a long term assessment capability tion (Dunn and Tyler 1969; Dunn 1970; Burton and was the ultimate research goal of the NUSCO winter idler 1984). In castern LIS, females begin to mature flounder studies. A combination of sampling pro-
~
at age 3 and 4 and males at age 2 (NUSCO 1987). grams and analytical methods is presently used to Average fecundity of Niantic River females is about examine the current abundance of the Niantic River 561,000 eggs per fish. Eggs are demersal and hatch in population for annual assessments of the spawning about 15 days, and larval deveJopment takes about ? stock. A computer population simulation model is months; both processes are temperature-dependent. used for assessing long-term effects of MNPS opera-Small larvae are planktonic and although many remain tion. The impact of fish impingement at MNPS has near the estuarine spawning grounds, others are carried been largely mitigated by the installation and opera-into coastal waters by tidal currents (Smith et al. tion of fish return sluiceways at MNPS Units 1 and 3. 1975; NUSCO 1989; Crawford 1990). Some of the The mortality of entrained larvae potentially has displaced larvae are returned to the estuary on subse- greater significance as the winter flounder, unlike quent incoming tides. but many of them are swept niany marine fishes, is a product of local spawning away frorn the area imo coastal waters, where survival with geographically isolated stocks associated with may be diminished. Larger larvae maintain some individual estuaries or specific coastal areas (Lobell control over their position by vertical movements and 1939; Perlmuucr LN7; Salla 1961). In particular, the may spend considerable time on the bottom. Follow- population of w'mier flounder spawning in the nearby ing metarnorphosis, most demersal young-of the-year Niantic River has been studied in detail to assess the winter flounder remain in shallow inshore waters. long-term effect of larval entrainment through the. Yearlings (age-1 fish) become photonegative and most MNPS cooling-water system. of them are usually found in deeper waters (Pearcy his repon section summarizes data collected during 1962; McCracken 1963). Some adult fish stay in 1992 and updates results reponed previously (NUSCO estuaries following spawning, while others disperse 1993). The 1993 spawning season was the eighth offshore. By summer, most fish leave warmer shal- year in which winter flounder have experienced impact low waters as their preferred temperature range is from the operation of all three MNPS units. The 12-15'C (McCracken 1963). Nevenheless, some NUSCO winter flounder stochastic population dynam-remain in the estuaries and were reponed to avoid ics model (SPDM) was used to simulate the long-term . s temperatures above 22.5'C by burying themselves in effects of historical and projected rates'of fishing cooler bottom sediments (O!!a et al.1969). Other mortality and simultaneous plant operation, resulting aspects of winter flounder life histo y have been in annual mortalities from impingement of juveniles .
- WinterFlounder 143
and adults and the entrainment of larvae through the various life history studies of the winter flounder prior MNPS cooling-water system. The rate of annual to the operation of Unit 3. Ongoing sampling pro-production loss due to entrainment was determined grams that contributed data to the Niantic River winter from updated mass balance calculations, which were flounder studies are shown in Figure 1, which includes first presented in NUSCO (1991b). The effect of the seasonal duration of sampling and timing relative impingement was included in the simulations as an to the annuallife-cycle of Niantic River winter floun-equivalent annual instantaneous mortality rate added to der. Brief descriptions of field methodologies used in fishing and was based on an analysis given in these programs are given below. Information on NUSCO (1992a). water temperature was obtained from continuous temperature recorders at the intakes of MNPS Units 1 Matcrials and Methods and 2; daily mean temperatures were determined from available records of 15-minute average temperatures. Sampling programs Monthly, seasonal, or annual means were calculated using daily means. Data needed to assess MNPS impact on the winter flounder come from several biological sampling Adult winterflounder Sampling programs. Some programs (e.g., Niantic River adult and larval surveys, age-0 survey) were designed to Sampling methodology for the adult winter flounder investigate specific life history stages of winter floun- spawning surveys in the Niantic River has remained der. Other information comes from year-round sam- basically unchanged since 1982 (NUSCO 1987). pling of the entire local fish community, such as the Each survey since 1982 started in February or early trawl monitoring program (TMP) and ichthyoplankton March, after most ice cover disappeared from the river, monitoring programs at MNPS and in Niantic Day, and continued through early April. Sun >cys ceased Additional information used in various assessments when the proportion of reproductively active females was presented in NUSCO (1987), which summarized decreased to less than 10% of all females examined for 5 Trawl rnonttoring
$$%%Q%
4
$h1%hk%%)) Age - 0 Juvenile Survey 3
$$%%\%%% lehthyoplankton Monitoring 2
Q%%k%h% Winter Flounder Larval Survey 1 k%k% Niantic River Winter Flounder Survey F lM lA lM lJ lJ lA lS lO lNlD lJ lF lM lA l y, Year 0 Year 1 y r , r
- 1. February-April sampling (spawning season) for adults and juveniles throughout the Niantic River.
- 2. February June larval sampling at three stations in the Niantic River and one in Niantic Bay.
- 3. Year round rnonitoring of allichthyoplankton at the MNPS discharges.
- 4. May September sampling of age 0 juveniles at two stations in the Niantic River.
- 5. Year-round monitoring of all benthic fishes at six stations near MNPS (juvenile data come from two stations in November, four in December, and six in January-April).
Fig.1. Current sampling programs contributing data for computation of winter flounder abundance indices (hatched area show months from which data were used in thh report). 144 Monitoring Studies,1993
1 I 1 1 2 consecutive weeks, an indication of completion of made with the East Lyme Waterford Shellfish Com- -l most spawning. In each survey, the Niantic River mission to protect habitat of the bay scallop was divided into a number of sampling areas, referred (Argopecten irradians). Winter flounder were collected to as stations (Fig. 2). Since 1979 no samples have on at least 2 days of each survey week using a 9.1-m been taken outside of the navigational channel in the otter trawl with a 6.4-mm bar mesh codend liner, , lower portioa of the river because of an agreement Fish caught in each tow were held in water-filled containers aboard the survey vessel before processing. i Since 1983, each fish larger than 20 cm was measured I to the nearest mm in total length and its gender ascer-tained. Before 1983, at least 200 randomly selected winter flounder were measured during each week of sampling. Those fish not measured were classified into various length and gender groupings; at mini-mum, all winter flounder examined were classified as 54 Niantic smann or largu than 15 cm. h gendu and trpmduc-tive condition of larger winter flounder was determined River by either observing eggs or milt or, as suggested by - g Smigielski (1975), noting the presence (males) or absence (females) of ctenii on left-side caudal peduncle scales. Before release, healthy fish larger than 15 cm 53 (1977-82) or 20 cm (1983 and after) were marked in a i specific location with a number or letter made by a { Keeny N brass brand cooled in liquid nitrogen. Marks and brand Cove location wera varied in a manner such that the year of marking u ould be apparent in future collections. 0 1km 51 Larvalwinterflounder sampling
} Winter flounder larvae entrained through the MNPS '
cooling water system were sampled at the MNPS-6 discharges (station EN, Fig. 3) since 1976. Collec-
)4 tions usually attemated between the discharges cf Units 1 and 2, depending upon plant operation and water flow. Larvae were collected in a 1.0 x 3.6-m plankton net of 333- m mesh deployed from a gantry systern. Four General Oceanic (GO) Model 2030 flow-meters were positioned in the net mouth to account 2 for horizontal and vertical flow variation; sample -
volume was determined by averaging the four volume 3 estimates from the flawmeters. Starting in 1993, the net was deployed for 3 to 4 minutes (filtering about 3
' 200 m ), but this varied depending upon the number of circulating pumps in operation and tidal stage. In previous years, sampling time was longer and filtered about 400 m 3. Sampling frequencies have varied since 1976 (NUSCO 1987). In 1993, samples were collected once per week during both day and night in February and June. During March through May, samples were taken on three days and nights per week.
Fig. 2. Location of stations sampled for adult winter "This was one day and one night sample less per week hunder during the spawning season in the Niantic River than during the same months from 1983 through in 1993. Winter Flounder 145
1KM 0l . 1 MI NIANTIC RIVER [N M NIANTIC BAY EN NB MILLSTONE PT. 0 ( Bl_ACK PT. Fig. 3. Location of stations sampled for larval winter flounder during 1993. 1992. Allichthyoplankton samples, including those based on knowledge gained during previous years and described below, were pn: served with 10% formalin. was designed to increase data collection efficiency Winter flounder larvae have been collected in while minimizing sampling biases (NUSCO 1987). Niandc Bay at station NB since 1979 and in the Larval sampling at the three Niantic River stations Niande River at stations A, B, and C since 1983 (Fig. usually started in mid-February. From then through 3). A 60-cm bongo plankton sampler was weighted the end of Man:h, daytime tows were conducted whhin with a 28.2-kg oceanographic depressor and fitted with I hour oflow slack tide. During the remainder of the 3.3 m long nets with mesh size of 202 m during season, until the disappearance of larvac at each sta-February and March and 333 m during the remainder tion, tows were made at night during the second half of the season. Volume of water filtered was deter- of a flood tide. From 1983 through 1990, sampling mined using a single GO flowmeter mounted in the was conducted 2 days a week. Starting in 1991, center of each bongo opening. The sampler was sampling was reduced to 1 day a week (NUSCO towed at approximately 2 knots using a stepwise 1991a). % rough 1992, station NB was sampled day oblique tow pattern, with equal sampling time at sur- and night every two weeks during February and at face, mid-depth, and near bottom. He length of tow least once a week from March through the end of the line necessary to sample the mid water and bottom larval winter flounder season. Beginning in 1993, strata was determined by water depth and tow-line station NB was sampled during the day from the start angle measured with an inclinometer. Nets were of the larval season though March and at night from towed for 6 minutes (filtering about 120 m 3). One April through the remainder of the larval season. In duplicate sample from the bongo sampler was retained 1991-93, an additional station (RM) was sampled for laboratory processing. The larval winter flounder from March through May at the rnouth of the Niantic - sampling schedule for Niantic River and Bay was River (Fig. 3) and collections at stations NB and RM 146 Monitoring Studies,1993
i
.l l
l
'l i
1 1KM 0l , 1 MI NIANTIC W LR , _\ RM } JORDAN ( COVE l y Sep k 4) Q gj Fig. 4. location of stations sampled biweekly by 1-m beam trawl for age 0 winter flounder from late May through Septem-ber of 1993. were taken consecutively near the time of maximum larval young in summer and during the subsequent fall flood tidal currents. Jellyfish medusae at the three and winter by the TMP. These fish became age-1 river stations were removed (1-cm mesh sieve) from when taken during the February-April adult spawning the samples and measured volumetrically to the near- surveys. est 100 mL The abundance of post-larval age-O winter flounder has been monitored at stations in the Niantic River Juvenile winterfloundersampling since 1983 (LR) or late 1984 (WA), and in Niantic Bay (RM and BP) since 1988 (Fig. 4). Through . Information on juvenile (age-0 and age 1) winter 1992, collections were made weekly, but in 1993 flounder was obtained from three sources (Fig.1). A sampling frequency was reduced to biweekly. River special sampling program specifically targeted post- stations were sampled during daylight from about 2 larval young-of-the-year. A second source of data is hours before to I hour after high tide. Depending the trawl monitoring program (TMP), and the third is upon the time of high tide in relation to sunrise or the Niantic River adult spawning abundance surveys, sunset, stations located in the bay were sampled before . during which winter flounder juveniles are collected or after those in the river, and, thus, were occupied at incidentally. Data on juvenile fish abundance were ] various tidal stages. During most years, sampling - ~j available from about May of their birth year into began during the third week of May, Monitoring con- j April of the following year. Juvenile indices were tinued through the end of September, unless no or few I refetTed to as age-0 when fish were collected as post- (< l m'2) young were taken during 2 consecutive sam-WinterFlounder 147 1 i i
pling periods, in which case the station was dropped. Relative annualabundance ofadults Young winter flounder were sampled using a 1-m beam trawl having two tickler chains and with inter- The relative annual abundance of winter flounder in changeable nets of 0.8 ,1.6,3.2 , and 6.4-mm bar the Niantic River during the late February-carly April mesh. In 1983, triplicate tows were made at LR spawning season is described by trawl catch per-using nets of increasing larger mesh as the season unit-effon (CPUE). An annual CPUE was calculated progressed. Beginning in 1984, two nets of succes- using the median catch following data standardization. sively larger mesh were used during each sampling Components of standardization included tow length, trip; nets were deployed in a random order. A change tow duration, weekly effort, and fish length and gender to the next larger mesh in the four net sequence was categories. Tow distance (with exceptions noted - made when fish had grown enough to become retained below) was fixed in 1983 because using the same tow by it. Use oflarger meshes also reduced the amount length at all stations was expected to reduce variability of detritus and algae collected. At each station, four in CPUE; previously, tows of variable length had replicate tows were made, two each with the two nets been taken at all stations. A distance of 0.55 km was in use. Rarely, because of bad weather or damage to selected as the standard because it represented the the net, only three tows were taken at a station. Tow maximum length of a tow that was formerly possible distance was estimated by letting out a measured line at station 1. Particularly during 1987 and 1989-91, attached to a lead weight as the net was hauled at tows one-half or two-thirds of this length were fre-about 25 m min l. The length of each tow was quently taken in the upper river to avoid overloading increased from 40 to 100 m in 20- or 40-m increments the trawl with macroalgae and detritus. Because catch at a station as fish abundance decreased over time, data from station 2 were used also in the TMP, tows Catches from the TMP (see the Fish Ecology there were made over 0.69 km, the standard for that section of this report for methods) were used to follow panicular sampling. Since 1990, tow distance at the abundance of age-0 winter flounder during fall and station I was reduced to 0.46 km because of the winter. In addidon to the TMP, juvenile winter construction of a new bridge at the mouth of the river flounder smaller than 15 cm in length (mostly age-1) and the destruenon of the old bridge. were caught Mong with adults in the annual Niantic Duration of tows varied and was usually longer in River spawning stock surveys. These fish were the lower river than in the upper river because of processed similarly as adults, although gender was differences in tidal currents and amounts of extraneous usually not specified, and the fish were not branded. material collected in the trawl. To lessen error in the When small winter flounder were abundant, a calculation of CPUE, data from exceptionally long or subsample of at least 200 fish was measured each brief tows made prior to 1983 were excluded from the survey week: otherwise, all specimens were measured, analyses. Catches of winter flounder larger than 15 cm in tows made throughout the spawning surveys Indices of abundance were standardized to either 15-minute tows at stations 1 and 2 or 12-minute tows at all other stations. 'Ihe Data resn!dng from the field sampling programs minimum length of 15 cm used for CPUE calculation described above were used to calculate annual and was smaller than the 20 cm used for mark and recap-seasonal indices of relative abundance. Indices, calcu- ture estirnates described below because of data limita-lated using various sampling statistics, were computed tions from the 1977-82 surveys. Effort was standard-for various life-stages of winter flounder, from newly ized within each year by replicating the median CPUE hatched larvae to adult spawners and also included estimate in a given week as needed so that effort (nutn- . estimates of egg production. Specifics of each abun- ber of tows) was the same for each week sampled. A dance index depended upon the panicular stage of life, 95% confidence interval (Cl) was calculated for each sampling effort, and suitability of the data; a detailed annual median CPUE using a distribution-free method description of each follows. The indices enabled based on order statistics (Snedecor and Cochran 1%7). timely assessments to be made regarding the current A second reladye index of abundance used the gender status of the Niande River winter flounder populadon and size distribution of the fish from aduh spawning and many of these data were used with the SPDM for survey catches standardized by variable weekly and long-term predictions of MNPS impact. 3early effort. Adjustments to the catches were made using sampling effort to insure that each size and sex 148 Monitoring Studies,1993
i l l l I group of fish was given equal weight within each This relationship was used with the annual standard-week of work, among weeks in each survey year, and ized catch of mature females and their length com- l to adjust for varying effort among years. Detailed position to calculate egg production. Annual mean j methods of calculating these values were given in fecundity was determined by dividing the sum of all l NUSCO (1989). To avoid confusion with the CPUE individual egg production estimates by the standardized index, this measure is referred to as " annual standard- catch of females spawning per year. ized catch" throughout the remainder of this report. Absolute estimates of spawning females and corre-The annual standardized catch was the basis for the sponding annual egg production estimates for 1977 calculation of annual recruitment and egg production through 1993 were determined by assuming that the described below. relative values represented 3.5% of the absolute values (see Absolute abundance estimates in Results and Abfolute abundance estimates of adults Discussion for how this fraction was determined). Annual estimates of the number of female spawners Absolute abundance estimates of winter flounder were also used in the derivation of a relationship spawning in the Niantic River were obtained using between stock and recruitment for Niantic River mark-and-recapture methodology and the Jolly (1965) winter flounder. stochastic model. This model is considered among the most useful in providing abundance estimates for open Development and growth, abundance, populations as long as basic assumptions are approxi. andmortality oflarvae mately met (Cormack 1968; Southwood 1978; Begon 1979; Pollock et al.1990). Annual absolute abun- Ichthyoplankton samples were split to at least one-dance estimates for Niantic River winter flounder half volume in the laboratory.- Sample material was larger than 20 cm were calculated by pooling together viewed through a dissecting microscope and winter all fish marked and released during each annual survey flounder larvae were removed and counted. Up to 50 and by observing the recaptures made in subsequent randomly selected larvae were measured to the nearest years. Absolute abundance estimates could not be 0.1 mm in standard length (snout tip to notochord generated for years prior to 1984 because of uncertain- tip). The developmental stage of each measured larva ty in data records and ambiguity in brands used during was recorded using the following criteria: the early surveys. Estimates were made of annual Stage 1. The yolk-sac was present or the eyes population size (N) and other model parameters, . were not pigmented (yolk-sac larvae); including survival ($), recruitment (B), and sampling Stage 2. The eyes were pigmented, no yolk-sac intensity (p), using the computer program ' JOLLY' was present, no fin ray development, (Pollock et al.1990). and no flexion of the notochord; Stage 3. Fin rays were present and flexion of the Adult spawning stock size notochord had started, but the left eye and egg production had not migrated to the midline; Stage 4. The left eye had reached the midline, The propordon of mature female winter flounder in but juvenile characteristics were not each 0.5-cm length increment beginning at 20 cm was present; estimated from qualitative observations of reproductive Stage 5. Transformation the to juvenile stage condition (percent maturity by 0.5-mm size-classes) completed and intense pigmentation made from 1981 through the presenL Pooled esti- present near the base of the caudal fin. mates were adjusted to give condnuously increasing Larval data analyses were based on standardized fractions of mature fish through 34 cm; all females densities (number 500m*3 of water sampled). A this length or larger were considered to be mature. geometric mean of weekly densities was used in - The fecundity (annual egg production per female) was analyses because the data generally followed a estimated for each 0.5-cm size-class by using the lognormal distribution (McConnaughey and Conquest following relationship determined for Niantic River 1993) and weekly sampling frequencies varied among winter flounder (NUSCO 1987): some stations. Because older larvae apparently re- ; mained near the bottom during the day and were not as fecundity = 0.0824-(length in em)* (1) susceptible to entrainment or the bongo sampler, data WinterFlounder 149 i
. - - . . ~. . from daylight sampics collected after March at stations mm was the approximate length at hatching. The EN and NB were excluded from abundance calcula- decline in the frequency of larvae in progressively tions, except for estimating entrainment at MNPS. larger size-classes (in 1 mm groups) was attributed to The distribution of larval abundance data over time both natural mortality and as a result of tidal flushing is usualfy skewed because densities increase rapidly to from the river, liess et al. (1975) estimated the loss a maximum and then decline slowly. A cumulative of larvae from the entire river as 4% per tidal cycle and density over time from this type of dismoution results also determined that the loss from the lower portion of in a sigmoid- shaped curve, where the time of peak the river was about 28% per tidal cycle. Thus, the abundance coincides with the inflection point. The weekly abundance estimates of larvae 3 mm and Gompertz function (Draper and Smith 1981; Gendron smaller at station C in the lower portion of the river 1989) was used to describe this cumulative abundance were re-scaled by a factor of 1.93 to compensate for distribution because the ir.flection point of this func- the 28% decline per tidal cycle (two cycles per day), tion is not constrained to the mid-point of the sigmoid The abundance of larvae in the 7 mm size-class was curve. The forrn of the Gompertz function used was: used to calculate an index of larval abundance just C, = a exp(-exp[ x-(t-p)]) (2) prior to metamorphosis. Because previous studies where C, = cumulative density at time t (NUSCO 1987,1989) showed a net import of larger i = time in days after February 15 !arvae into the Niantic River, the weekly abundance of a = total or asymptotic cumulative density larvae in the 7 mm size-class at station C was not - p = inflection point scaled in days since February adjusted for tidal flushing. To calculate each annual 15 rate of mortality, sums were made of weekly mean x = shape parameter abundance indices (three stations combined) of The time of peak abundance was estimated by the newly-hatched larvae (after adjusting for tidal flushing) parameter p. The origin of the time scale was set to and larvac in the 7 mm size-class. Survival rates from February 15, which is the approximate date when hatching through larval development were estimated as winter flounder larvae first appear in the Niantic the ratio of the abundance index of the larger larvae (7< River. Least. squares estimates, standard errors, and mm size-class) to that of the smaller larvac (3-mm and asymptotic 95% confidence intervals for these parame- smaller size-classes). ters were obtained by fitting the above equation to the The presence of density-dependent mortality was cumulative abundance data using nonlinear regression investigated by relating annual larval abundance in the methods (SAS Institute Inc.1985). The cumulative 7 mm and larger size-classes from station EN to the data were obtained as the running sums of the weekly annual egg production estimate for the Niantic River , geometric means of the abundance data. The a parame- using the following relationship (Ricker 1975): ter of the cumulative curve was used as an index to log,(Ll E) = a + bE (4) - compare annual abundances. where L = annual larval abundance of larvae 7-mm and A
- density" function was derived algebraically by larger at EN as estimated by n (see Eq. 2) calculating the first derivative of the Gompertz func. E = annual estimate of egg production in the tion (Eq. 2) with respect to time. This density func- Niantic River tion, which directly describes the larval abundance a = imercept over time (abundance curve), has the form: b = slope or index of mortality dependence upon d, = a' K-exp(-exp[ x-(t p)]- w-[t -p]) (3) annualegg abundance where d, = density at time t and all other parameters Since the ratio L divided by E represents the fraction are as described for Equation 2, except for n*, which of larvae surviving from eggs to 7 mm, density-was re-scaled by a factor of 7 (i.e., a" = 7a) because dependent mortality may be assumed when the slope
' the cumulative densities were based on weekly geomet. (b)is significantly different from zero. This mortality ric means and, thus, accounted for a 7-day period. is compensatory when the slope b is negative and Larval mortality rates were estimated from data depensatory if positive.
collected at the three Niantic River stations; data from Regression analyses were used to examine possible 1983 were excluded as smaller larvae were under- relationships between variables and, at times, to make sampled because of net extrusion (NUSCO 1987). predictions. Ordinary least-squares linear regression The abundance of 3-mm and smaller larvae was used was used when the independent variable was assumed to calculate an index of newly-hatched larvae because 3 to be measured without error (e.g., water temperature). 150 Monitoring Studies,1993
The test of a relationship was based on the slope Abundance ofjuveniles duringfall and winter being significantly (p 5 0.05) different from zero. Funedonal regression methods developed by Ricker in fall and early winter, age-0 winter flounder gradu-(1973,1984) were used in the cases where the indepen- ally disperse from areas near the shoreline to deeper dent variable was measured with error (e.g., abundance waters. Catch of these fish during this time period at indices). For functional regressions, the probability the TMP stations (see the Fish Ecology section that r (correlation coefficient) was significantly (p s elsewhere in this report for methods) was also used as 0.05) different from zero was the criterion used to an index of relative abundance. Data used included decide whether a valid relationship existed prior to November through February for inshore stations (NR determining the slope and the 95% confidence interval and JC), December through February for nearshore for the slope. Niantic Bay stations (IN and NB), and January and Febmary at offshom stations (TT and BR). In previ-Abundance, growth, and mortality ous reports, sample size varied among years because ofjuveniles in Summer of when samples were taken in these months. For this and subsequent reports, sample size was set at 42, To analyze data and calculate CPUE, the catch of which meant that some annual values were recalc-young-of-the-year winter flounder in each of the three ulated. These catches were pooled and used to calcu-or four replicated 1-m beam trawl tows was standard- late year-class abundance described by a A-mean ized to a 100-m tow distance before taking a mean; CPUE (NUSCO 1988b). This index of abundance is 2 density was expressed as the number per 100 m of the best estimator of the population mean when the bottom. For some comparisons among years, a mov- data come from a distribution that contains numerous ing average of three (1983-92) or two (1993) weekly zero values and is approximately lognormal density estimates was used to smooth fluctuations in (Hennemuth et al.1980; Pennington 1983,1986). abundance. The annual median CPUE ofjuveniles smaller than Nearly all of the age-0 winter flounder collected 15 cm (mostly age-1 fish) taken during the adult , were measured fresh in either the field or laboratory to winter flounder spawning surveys was determined as the nearest 0.5 mm in total length (TL). During the described previously for fish larger than 15 cm. first few weeks of study, standard length (SL) was also Median values were calculated for stations in the lower measured because many of the specimens had damaged Niantic River navigational channel (1 and 2) as well - caudal fin rays and total length could not be ascer- as for all river stations combined, when sufficient data tained. A relationship between the two lengths deter- were avaliable. For comparative purposes, an annual mined by a functional regression was used to convert A-mean abundance index of juvenile fish of similar SL to TL whenever necessary: size was also determined using catch data fmm the five TL in mm = -0.2 + 1.212-(SL in mm) (5) trawl monitoring program stations outside of the Growth of age-0 winter flounder at each station was Niantic River during the period of January through examined by following weekly mean leryths through- April, which temporally overlapped the adult spawn-out the sampling season. Mean Ic.ogths of young ing surveys. taken at the Niantic River stations LR and WA from late July through September were compared using an Stock andrecruitment relations /dp analysis of variance; significant differences among means were determined with Duncan's multiple-range A stock-recruitment relationship (SRR) described by test (SAS Institute Inc.1985). Ricker (1954,1975) is the basis of the life-cycle To calculate a total instantaneous mortality rate (Z), algorithm that drives the population dynamics sim- l all young were assumed to comprise a single cohort. ulation model of Niantic River winter flounder. A catch curve was constructed such that the natural Application of this SRR to MNPS winter flounder logarithm of density was plotted against time in stock assessment was described in detail in NUSCO weeks; the slope of the descending portion of the (1989, 1990). The stock and recruitment data for l curve provided an estimate of the weekly rate for Z. determining the SRR were derived from the catch-at-Once this rate was determined, the monthly mortality age of female winter flounder during the Niantic River rate (Z ) was calculated as (Z)(30.4 / 7). spawning survey. Because the spawning stock is made up of many year-classes, the true recruitment s WinterFlounder 151
consists of the total reproductive contribution over the Niantic River for fish age-3 to 5; all females age-6 and life of each individual in a given year-class (Garrod and older were assumed to be mature. Because the esti. Jones 1974; Cushing and Horwood 1977). herefore, mates of age-3 fish were thought to be unreliable, this the index of annual parental stock size was based on estimation process was only carried through the 1989 derived egg production and the index of recraits or year-class (age 4 females taken in 1993). He adjusted year-class size was based on calculated egg production numbers of mature fish provided an index of the fully accumulated over the life-time of the recruits. This recruited year-class expressed as the aggregated number method accounted for variations in year-class strength of female spawners passing through each age-class. and in fecundity by size and age. The assumptions An implied assumption was that catches in the and methods used to age Niantic River winter flounder Niantic River were representative of the population, and to calculate a recruitwt index expressed as with the exception of immature fish that did not enter equivalent numbers of female spawners were described the river until fully recruited. Although this recruit-in detail in NUSCO (1989,1990) and summarized ment index could be used together with the annual below. number of female spawners to derive an SRR, this ., Stock and recruitmeni indices. Methods would ignore size composition differences that affected used to calculate the annual standardized catch index annual egg production. Therefore, the above index and total egg production of the parental stock were was adjusted for differences in fecundity among fish given previously. The recruitment index was deter- using the length fecundity. relationship for Niantic mined by applying an age-length key described in River winter flounder given above (Eq.1). Finally, NUSCO (1989) to the annual standardized catches of annual egg production was summed up over the life-females partitioned into length categories. A common time of each year class to determine the recruitment age !cngth key was used over all years because index as eggs and, then, converted to equivalent female Witherell and Burnett (1993) reported that no trends spawners at the rate of one female spawner for each were observed in mean length-at-age during 1983-91 561,000 eggs (i.e., the mean fecundity), for Massachusetts winter flounder despite a 50% SRR parameters and biological reference reduction in biomass over that period. Aging the points. The Ricker SRR appeared best suited for ' females allowed for the determination of their numbers use with the Niantic River winter flounder stock ~ by year-class present at ages 3,4,5, and 6+ during because the relationship between recruitment and successive spawning seasons. The age-6+ group was spawning stock indices was a dome-shaped curve with ., further subdivided into the numbers of fish expected to substantial decline in recruitment when the stock was survive to a terminal age of 15 by assuming various larger than average (NUSCO 1989). Furthermore, > annual instantaneous mortality rates as fishing pres- this particular form of a SRR has been applied to sure increased from the 1970s into the 1990s. To other New England flounder stocks (Gibson 1989). follow each year-class from 1977 through 1989 to its The mathematical form of this SRR is: terminal age (e.g.,2004 for the 1989 year-class), R, = a P,.exp( P,) (6) values of Z (= F + M) were used that represented where R, is the recruitment index for the progeny of estimates of current and anticipated annualinstanta- the winter flounder spawning stock P,in year t and a neous rate of fishing (F) as provided by the Connecti- m are parameters estimated from the data. The a a.l cut Department of Environmental Protection (CT parameter describes the growth potential of the stock - DEP). The instantaneous natural mortality rate (M) and log,(a), the slope of the SRR at the origin, is was assumed constant at 0.35 over all years. These equivalent to the intrinsic natural rate of increase were the same mortality rates used in the stochastic (Roughgarden 1979) when the stock is not exploited. population dynamics model, discussed below. From The parameter is the instantaneous rate at which' observations made of abundance and age over the recruitment declines at large stock sizes due to some - years, a large fraction of age-3 females, considerable form of density-dependent mortality. The natural numbers of age-4 fish, and even some age 5 females logarithm of winter flounder recruitment was found were apparently immature and not present in the correlated with mean water temperature during Febru-Niantic River during the spawning season (NUSCO ary at the intakes of MNPS, which is when most 1989). Dus, the total number of females was reduced spawning and early larval development occurs to spawning females using length-specific proportions (NUSCO 1988a,1989). Therefore, the parameters a of mature fish estimated from annual catches in the and were estimated initially by fitting Equation 6 to 152 Monitoring Studies,1993
the data and then re estimated under the assumption The fishing rate for " recruitment overfishing" has been that there was a significant temperature effect; this recently defined for winter flounder stocks as the rate was accomplished by adding a temperature-effect of fishing that reduces the stock biomass to less than component to Equation 6. Following Lorda and 25% of the maximum spawning potential (Howell et Crecco (1987) and Gibson (1987), annual mean water al.1992). temperatures for a particular period were used as an Although the above equations (911) can be used to explanatory variable to adjust the two-parameter SRR calculate equilibrium stock sizes and fishing rates for for temperature effects, which served to reduce recruit- the winter flounder, the results are only deterministic ment variability and obtain more reliable parameter approximations that ignore age-structured effects. estimates for the SRR. The temperature-dependent herefore, these equations are primarily useful to cal-SRR had the form: culate initial values of the corresponding biological R, = a Prexp(- p P,) exp($ Treb) (7) reference points. These are better estimated through where the second exponential describes the effect of simulations using the SPDM or other similar pop-February water temperature on recruitment and the uladon or production models that include age suture new parameter & represents the strength of that effect. and both natural and fishing mortality. This effect either decreases or increases the number of recruits per spawner produced each year because temper- Assesstnent of MNPS operation on ature was defined as the deviation (Treb) of each particu- Niantic River winter flounder far mean February temperature from a long-term (1977-89) average of February water temperatures. Several well-established methods available for stock When the February mean water temperature is equal to assessment are based on stock recruitment theory the long-term average, the deviation (T Feb) in Equa- (Smith 1988). These methods assume constant fish-tion 7 becomes zero and the exponential term equals ing rates and populations with stable age-structure, unity (i.e., no temperature effect). Thus, Equation 7 which result in equilibrium or steady-state stocks that reduces to its initial form (Eq. 6) under average temper- replace themselves year after year. Some analytical ature conditions. Nonlinear regression methods (SAS methods are based on equilibrium equations, such as Institute Inc.1985) were used for estimating the Equations 9 through 11, which have been modified to parameters in the above equations. incorporate effects of mortality caused by activities Fishing mortality (F) is an important factor affect- other than fishing. Several problems may exist with ing the growth potential of the stock (Goodyear 1977) an SRR-based approach to impact assessment at and, thus, is relevant for assessing other impacts. MNPS Because stock recruitment theory (Ricker Because fishing and natural monality of winter floun- 1954) was developed for semelparous fish (i.e., those der take place concurrently thmugh the year, the actual which spawn only once in their lifetime), Equation 11 fraction of the stock removed by the fishery each year may provide unreliable estimates of equilibrium stock (i.e., the exploitation rate) is obtained as: sizes for iteroparous fish (multi-aged spawning u = (F/Z)(1 exp[-Z]) (8) stocks), such as the winter flounder. Although the Stock recruitment theory and the interpretation of parameter a in Equation 9 could be adjusted for the several biological reference points derived from effect of repeat spawning, this equation also assumes Ricker's SRR model were discussed in detail in that no fishing mortality occurs prior to maturation. NUSCO (1989). The equilibrium or sustainable stock This assumption cannot be met in the case of winter size of an exploited stock (i.e., when F > 0) is given flounder because many immature fish (ages-2 and 3) by: are vulnerable to fishing gear. Wigley and Gabriel PE(F) = (log,[a] - F) / (9) (1991) noted that concentrations of immature winter Rearranging the terms and solving for the rate of flounder found off Rhode Island may be subjected to fishing that would achieve a given equilibrium stock significant monality from fishing. Howell and size results in: Langan (1987,1992) found that discard monality rates F = loge (a) - -(PE(F)) (10) of trawl-caught fish in New England waters may be For F = 0 Equation 9 becomes the equilibrium or substantial. Simpson (1989) reported that about 72% replacement level of the unfished stock: of LIS winter flounder landed by the commercial P,y, = (log,[a]) / p (11) fishery were between 28 and 32 cm; many_of these fish would have been age-3, Additional problems are WinterFlounder 153 I
found when applying deterministic models (i.e., direct measure of impact on the local winter flounder assuming steady-state conditions) to fish stocks whose stock. Annual estimates were determined using larval exploitation utes are not stable, especially when auch densities at station EN (Fig. 3) and the volume of stocks increase in abundance, as in the case of the cooling water used by MNPS, ne Gompertz density. winter flounder during the late 1970s and early 1980s function (Eq. 3) was fitted to larval data and daily (Smith et al.1989). Environmental variability also densities (number 500m4 ) were calculated.' Daily results in year-to-year variation of natural mortality entrainment esdmates were determined after adjusting rates, which further weakens the results of de' An- for the daily condenser cooling-water volume and an istic assessments. annual estimate was determined by summing all daily An approach to stock assessment incorporating estimates during the larval season. environmental variability and all types of mortality, both constant and variable, involves the computer MASS-balance calculatiora simulation of fish populations using a simple model of population renewal with spawning stock feed-back ne number of winter flounder larvae entrained de-(e.g., a functional stock-recruitment relationship). pends upon larval densities in Niantic Bay. Potential This approach has two advantages: assumptions of impact to the Niantic River stock from larval entrain-population equilibrium are not necessary, and much ment should be related to the number of larvae in detail can be incorporated into the conditions or scenar- Niantic Bay that originated from the river. Mass. ios used to simulate changes in fish populations balance calculations were used to investigate whether through time. An additional advantage is that Monte the number of winter flounder larvae entering Niantic Carlo methods readily provides the stochastic (as Bay from the Niantic River could sustain the number opposed to deterministic) framework needed for oflarvae observed in the bay during the winter floun-probabilistic risk assessment and for tesdng hypothe- der larval season each year (19M-93). Three potential ses about the probable size of the stock at some future larval inputs to Niantic Bay include eggs hatching in point. This simulation approach was applied in the bay, larvae flushed from the Niantic River, and NUSCO (1990) to assess the impact of larval entrain- larvae entering the bay from LIS across the boundary ment under a simple scenario. In NUSCO (1991b), between Millstone Point and Black Point (Fig. 3). the same approach used various combinations of The few yolk sac larvae collected annually in Niantic , historic and projected fishing and larval entrainment Bay suggested that minimal spawning and subsequent rates to assess more realistically the impact of MNPS hatching occurred in the bay, which was therefore < operations on local winter flounder. In NUSCO considered a negligible source oflarvae. Larvae were - (1992a), the impact resulting from the impingement known to be flushed from the river into the bay and ofjuvenile and adult winter flounder was also simulat- this input to the bay was estimated from available ed. He basic steps leading to the finalimpact assess- data. The number of larvae entering Niantic Bay from ment using this simulation approach are: direct estima. LIS was unknown. Four ways in which larvae may tion of annual larval entrainment rates at MNPS; leave Niantic Bay include natural mortality, entering - mass balance calculations to estimate the fraction of the Niantic River during a flood tide, being entrained Niantic River annual flounder production lost through at MNPS, and flushing from the bay into LIS. Esti-larval entrainment at MNPS; estimation of the equiva- mates could be made for the number of larvae lost lent instantaneous mortality rates of females that were through natural mortality, entering the Niantic River, attributed to impingement; stochastic simulation of and entrained at MNPS, but little was known about the winter flounder stock dynamics to predict stock the number of larvae flushed into LIS. He numbers biomass at selected level! af entrainment and fishing of larvae flushed to and from LIS were combined as rates; and an analyses of simulation results leading to the unknown (Source or Sink) in the mass balance estimates of the probability that the stock would fall calculations. Thus, the form of the mass-balance below selected reference sizes, equation was: NB:,3 = NB: Ent - Mort + FromNR - ToNR t Estirnates oflarval entraintnent at MNPS (Source or Sink) (12) where t = time in days The estimated number of larvae entrained in the NBa 3 = number of larvae in Niantic Bay 5 days ! MNPS condenser cooling water system each year is a after day t (instantaneous daily estimate) 154 Monitoring Studies,1993
NB, = initial number of larvae in Niantic Bay on through 1993 by NUSCO staff. Mortality was parti-day t (instantaneous daily estimate) tioned among developmental stages by comparing the Ent = number of larvac lost from Niantic Bay due rates of decline of predominant size-classes for each to entrainment in the condenser cooling- stage. Each developmental stage was assigned a water system (over a 5-day period) portion of the total annual larval mortality rate (Z); Afort = number of larvac lost from Niantic Bay similar mortality rates were assumed for Stages 3 and due to natural mortality (over a 5-day 4. Although estimating stage-specific mortality in-period) . this manner was not precise, sensitivity analysis on-FromNR = number of larvae flushed from the the mass-balance calculations (NUSCO 1991b) indi. Niantic River (over a 5-day period) cated that larval mortality was the least sensitive - ToNR = number of larvae entering the Niantic parameter. These annual rates were modified to daily River (over a 5-day period) stage-specific mortality rates by assuming 10-day Source or Sink = unknown number of larvae in stage durations for Stages 1,3, and 4 larvae, and 20 Niantic Bay that flush to LIS days for Stage 2 larvac. The proportion of each stage or enter the bay from LIS collected at station EN during each 5-day period was (over a 5-day period) applied to the daily standing stock for Niantic Bay Solving for the unknown Source or Sink term, the (NB,) to estimate the number of larvae in each devel-equation was rearranged as: opmental stage for stage-specific mortality calcu-Source or Sink = NB,,3 - NB, + Ent + Afort - lations. The daily loss due to natural mortality was FromNR + ToNR (13) summed for each 5-day period (Afort). Because these mass-balance calculations were based on 'Ihe 5-day input of lasvae to Niantic Bay from the the change in the number of larvae in Niantic Bay river (FromNR) was based on daily density estimates over a 5-day period: for station C in the river after adjusting for the rate of 5-day change = NB, 3 -NB, (14) flushing between station C and the mouth of the river. Thus: To determine the relationship between the esti.nated Source or Sink = 5 day change + Ent + Afort - daily density at station C and the average density of fromNR + ToNR (15) larvae leavirg the river on an ebb tide, the geometric Daily abundance estimates were derived from the mean density of samples collected during an ebb tide Gompertz density equation (Eq. 3) and the daily densi- for ten import-export studies conducted at the mouth ties for Niantic Bay at two points in time (NB,and of the Niantic River during 1984,1985, and 1988 NB, o) for each 5-day period were calculated fmm data (NUSCO 1985,1986,1989) were compared to the collected at stations NB and EN combined. These estimated daily densities at station C. 'The average densities, adjusted for the volume of Niantic Bay density of larvae flushed from the Niantic River was j (about 50 x 106m 3;E. Adams, Massachusetts Insti-estimated by the significant (r = 0.969; p = 0.001) tute of Technology, Cambridge, MA., pers. comm.), functional regression equation: prcvided an estimate of the instantaneous dsly stand- FromNR =. 9.751 + 0.473-(Daily density at ing stock. The difference between these two esdmates station C) (16) (NB, and NBs ,3) was the term 5-day change in Equa- The 95% confidence interval for the slope was 0.387 - tion 15. The selection of 5 days as the period of 0.579. The estimated average density, the average change was arbitrary and a cursory examination of tidal prism of 2.7 x 106 m (Kollmeyer 1972),and results based on 10-day periods showed that the same about 1.9 tidal prisms per day were used to estimate conclusions were reached with either 5 or 10 day the daily flushing of larvae from the river into Niantic periods. Bay. This daily input to the bay was summed for Daily entrainment estimates were based on data col- each 5-day period to calculate the term FromNR in the lected at station EN and the actual daily volume of mass-balance equation, condenser cooling water used at MNPS. The daily Stepwise oblique tows were collected during 1991 - entrainment estimates were summed over each 5-day in the channel south of the Niantic River railroad period (Ent). Annual stage specific mortality rates for bridge (station RM) during a flood tide to estimate an 1984-89 were determined by Crecco and llowell average density for ToNR (NUSCO 1992a). In 1992 (1990), for 1990 (V. Crecco, DEP Division of Marine and 1993, sampling again was condueted at RM Fisheries Old Lyme, CT, pers comm.),and for 1991 during a flood tide, but the co!!ections were made by WinterFlounder 155 i
t L mooring the research vessel to the railroad bridge and age 1) in the life-cycle simulation, the population taking continuous oblique tows. Comparison of model simply describes the annual reduction of each densities from the paired stations of NB and RM year-class through natural mortality and fishing, showed a poor relationship. Herefore, daily densities together with aging and reproduction. This process at the two stations were estimated using the Compertz occurs at the beginning of each model time-step of i density curve (Eq. 3). For station RM in 1992, tha length equal to 1 year. The projection of adult fish equation could only be adequately fit by smoothNg populations over time has been implemented in many the data using a 3-week running average pr' to models by means of Leslie matrix equations (e.g., calculating a weekly cumulative density. For IW3, Hess et al.1975; Vaughan 1981; Spaulding et al. the Gompertz function could not be fit to the data 1983; Reed et al.1984; Goodyear and Christensen collected at station NB. Therefore, data from both 1984). In the SPDM, adult winter nounder were station NB and EN were combined to calculate the projected over time by grouping fish into distinct age-weekly geometric means prior to fitting the Gompertz classes and by carrying out the computations needed function and estimating daily densities for Niantic (mostly additions and multiplications) iteradvely over > Bay. Daily density estimates for 199193 were com- the age index (1 through 15) and over the number of bined and functional regression was used to determine years specified for each simulation. His approach ' the relationship between abundance at stations NB and was algebraically identical to the leslie matrix formu-RM. The average density of larvae flushed from latica, facilitated the understanding of how the model Niantic Bay into the river was estimated by the signifi- works, and simplified the computer code when des. cant (r = 0.705; p = 0.001) functional regression cribing the fish population either as biomass (allow-equation: ing for size variation within each age-class) or num-ToNR = 128.149 + 2.073WB, (17) bers of fish. A similar implementadon of an adult : De 95% confidence interval for the slope was 1.827 - fish population dynamics simulation was used by 2.351. After being adjusted for the average tidal prism Crecco and Savoy (1987) in their model of Connecti-and the number of tidal prisms per day, these daily cut River American shad (Alosa sapidissima). estimates of the number of larvae entering the river ModtI cornponents. Figure 5 illustrates the during a flood tide were summed over each 5-day components of the computer program used for the period to calculate the tenn ToNR in the mass-balance SPDM. Components depicted by solid line boxes equation. Because of the large intercept in the above constitute the model presently in use and one depicted regression line when no larvae were present in Niantic by a box with dashed lines illustrates a part of the Bay (NBe = 0), the term ToNR was conservatively set model that was not used in the present application, to zero. The term Source or Sink in Equation 15 but could be used in future applications. De function-represents the net loss from or gain to Niantic Bay of ality of most model components should be clear from larvae from LIS during a 5-day period that is required the flow chart and no funher details will be provided, to balance the calculation. For a net loss of larvae Some critical components, such as the one labeled (flushed to LIS), the Source or Sink term would be age 1 cohort and the two random input boxes are , negative and for a net gain of larvae (imported from described below. A list of the actual input data used LIS), the Source or Sink term would be positive. in the application of the model to the Niantic River winter flounder stockis also given. Stochastic simulation of winter ne most criucal aspects m the formulation of a flotuuter stock dynamics stock-recruitment based popuiation modei are the specific equation and parameters used to calculate total Modeling strategy and background. The monality during the first year of life (i.e., frorn egg stochasde population dynamics model (SPDM) devel- through age-1). The equation used for this purpose in , oped for the Niantic River winter flounder stock was the SPDM was derived from Ricker's equilibrium based on the Ricker SRR fitted to the data, even equation for Zo (total instantaneous mortality from though Equation 7 does not explicitly appear in the egg through maturation age). This involved the exten-model formulation. The mechanisms underlying the sion of stock-recruitment theory, which was developed Ricker form of recruitment are incorporated in the set for fish that spawn only once, to iteroparous fish with of equations that the model uses to calculate mortality multi-age spawning stocks. He form of the equation through the first year of life. Beyond that point (i.e., as used in thepresent model was: , 156 Monitoring Studies,1993
.]
'i l
input data and - simulation parameters Y Random
- water temperature
.............. 3 2 e Hatching ari.ii.uval
. . . . . . . . . . . . . . . distribution l. . . . . . .... 3 l i
. . . .k'{ Mas + Lalance '
calcula-l l
, a l..tio.n.s.o.f
. e.n.tr.ainm.e.nt.).
.. J e l
Y 2 Compensation, ' l y Entrainment and 4 --------------------- > Age 1 cohort 1 RanJom noise V Adult cohort calculations with Annual adult Probabilistic impingement, p population y risk natural, and fishing mortality estimates assessment V- V V Spcwning stock size - and. OUTPUT Egg production estimates Fig. 5. Disgram of NUSCO stochastic population dynamics computer model for assessing the long term effect of larval) winter flounder entrainment at MNpS. Dashed toxes and arrows refer to components and calculations which are not an integral part of the model. Zo,, = log,(FEC) + log,(ASF) log (n) + n,- according to the size of the annual spawning sto'c k P,.
$,WT, Z ij + p P, (18) The complete derivation of the above equation was '
where the subscript t denotes the time step (each time- given in NUSCO (1990: appendix to the winter. step represents a year) and non-subscripted terms flounder section). The scaling factor ASF is a multi-remain constant from year to year; a, p, and $ are the plier that converts age-3 female recruits into the total parameters of the SR function (Eq. 7); FEC is the spawning potential of the year-class. This spawning mean fecundity.of the stock expressed as the number potential is defined as the cumulative number'of of female eggs produced per female spawner; ASF is a mature females from the same year-class that survive scaling factor to adjust a for the effect of a multi-age to spawn year after year during the lifetime of the fish. spawning stock; n, and WT, are independent random The algebraic form of this multiplier is identical to - variates from two specified normal distributions - the numerator of Equation A 4 in Christensen and i ., described below; Z ia is the instantaneous mortality Goodyear (1988). . . , through the immature age-classes; and the last term Stochasticity in the winter flounder model (Fig. 5) . ($ P,) is the feed back mechanism simulating stock- has two annual components: a random term that rep-
' dependent compensatory mortality, which varies resents uncertainties associated with the estimate of WinterFlounder 157
Ricker's a parameter and annual eny' onmental vari- Ricker form of SRR, it was assumed that stock-ability in the form of random dev:.itions from the dependent compensation and the postulated effect of long-term mean February water %nperature. These water temperature on larval survival (Eqs. 7 and 18) two components of annual variability are incomorated applied reasonably well to the Niantic River winter into the calculation of each new year-class via the flounder stock. A second assumption was that the mortality from egg to age-1 (Eq.18). The term n,in three parameters of the SRR were correctly estimated Equation 18 (random noise) is simulated as indepen- and that a, in pardcular, was a reliable estimate, dent random variates from a normal distribution with Although the population was not assumed to be at zero mean and variance equal to 2c . De value of a is steady state, the average fecundity and survival rates esumated during the model calibration runs as the for fish age 1 and older were assumed to remain fairly. amount of variance required to generate a values stable over the period corresponding to the time series within the 95% confidence interval of the estimate of data used to estimate the SRR parameters. Although a used in the model (NUSCO 1990). Similarly, the this last assumption can generally be met in the ce term $ WT, in Equation 18 represents the effect of of fecundity rates and adult natural rnortality, fishing annual environmental variability of February water mortality rates are much less stable. Changes in temperatures on larval survival. His effect becomes exploitation rates from year to year should not cause random when the February water temperatures are estimation problems as long as the changes are not themselves simulated as independent random variates systematic (i.e., change in the same direction year from a normal distribudon with mean and variance after year). Because these assumptions are seldom equal to the mean and variance of February water completely met, early applications of the model temperatures at the MNPS intakes from 1977 through (NUSCO 1990) included calibration runs to validate 1989. predictions under both deterministic and stochastic The stochastic simulation of fish population dynam- modes by comparing model results to recent series of ics provides a framework for probabilistic risk assess- stock abundance data. Finally, no temperature trend or ment methodology. This type of assessment is based large-scale environmental changes (e.g., global warm-on Monte Carlo methods (Rubinstein 1981), where ing) were assumed to have occurred during the years many independent random replicates of the time-series simulated in each population projection. are generated so that the mean of the series and its Model input data. The dynamics of the Niantic standard error can be estimated. Monte Carlo replica- River winter flounder stock were simulated using the tions can be used to derive the sample distribution SPDM under a credible real time scenario running function (Stuart and Ord 1987) without assuming a from 1960, well before operation of Unit 1, to 2060, . known statistical distribution. His methodology was long after the projected shutdown date for Unit 3 in used to assess the risk of stock reduction resulting 2025 (Table 1). The scenarios used power plant from the effects of entrainment and impingement at effects based on actual generating units in operation MNPS. The probabilities of stock reductions were each year, concurrently with estimates of F that were empirically derived from Monte Carlo replicates of the based on historic and projected rates of commercial time-series of impacted stocks. exploitation and sport fishing for winter flounder in SPDM assumptions and limitations. Connecticut. Parameters used in the SPDM included: Major assumptions relate to the underlying form of F, with some additional mortality equivalent to losses the SRR used and the rrliability of the SRR parameter from impingement (IMP); conditional mortality rates estimates. Because the SPDM incorporated the (i.e., fraction of the annual production of winter TABLI 1. Couting wster acquirernents and dates of operadan for MNPS Units I through 3, each with an assumed hfe span of 40 yem. Coohng.waier flow Fracuan of MNPS First year of Projected last year Umt (mtsec'8) total flow Start-up date entrainment of operadon 1 29.18 o.227 November 1970 1971 2010 2 37.62 o.292 December 1975 1976. 2015 3 61.91 o.481 Apr01986 1986 2025 MNPS totat 128.71 1.000 158 Monitoring Studies,1993 .~
flounder removed as a result of power plant operation) recent DEP esthnates (V. Crecco, C DEP, Old determined for larval entrailment (ENT); a schedule of Lyme, CT, pers. comm.). These explaitation rates ! changes when any of these rates was not assumed took into account length-limit regulations in effect constant; and the length of the time-series in years, from 1982-93 and from changes in regulations pro- , The combined mortality of F + IMP was used only posed by the DEP to reduce fishing mortality in ! during the simulation period (1971-2025) that corre. Connecticut waters (Tables 2 and 3). Vulnerability i I sponded to MNPS operation (Table 1). factors for age-classes 1 through 5+ were calculated for ! Because the ability of a fish stock to withstand the commercial fishery (60% of the total winter floun. additional stress is reduced by fishing mortality (Good- der catch) that were based on: actual or proposed ; year 1980), simulations of the long term entrainment changes in length limits and minimum commercial ! I of winter flounder larvae also included effects due to trawl fishery codend sizes; the size-at-age of female the substantial exploitation of the stock. The annual Niantic River winter flounder at mid-year (age + 0.5) p schedule of nominal fishing rates was determined from determined using the von Bertalanffy growth equation TABLE 2. Eastem long Island Sound winter flounder length-limit and seasonal closun reguladons in effect or proposed for the commercial i and sport fisheries since 1982. 12ngth linut in inches length lindt in mm Period Commercial fishery Sport fishery Commercial fishery Sport fishery Seasonal closure i 1 l 1982* 8 8 203 203 None l 1983 (Jan May) 8 8 203 203 None l 1983 (Jun-Dec) 8 279 11 203 None l 1984 (Jan-Aug) I1 8 279 203 None 1 1984 (Sep.Dec) 10 8 254 203 None -i' 1985 1986 10 10 254 254 None 1987 (Jan.Aug) 10 10 254 254 Dec I Mar 31 (within Niande River) 1987 (Sep.Dec) 11 10 279 254 Dec 1 - Mar 31 (within Niantic River) 1988 19936 11 10 279 .254 Dnc 1 Mar 31 (within Niande River) 2 19945 12 Il 305 279 Nov 14 - Apr 15 (in all state waten)
- Prior to 1982 there were no sin reguladons. but it was assumed that fish between 6 inches (152 mm) and 8 inches (203 mm) were subjected to about 50% of the nommal fishing monality for each year. Fish larger than 8 inches were fully recruited to the fishery.
- Minimum trawl mesh codmd sin alsoincteased from 4.5 to 5.0 inches,
- At the Ume of preparadon of this report, these changes were proposed by the DSP (P. Ilowell. CT DEP, Old Lyme, CT, pen comm.) for implementadon (also includes an increase in the minimum trawl mesh codend siu to 5.5 inches).
TABLE 3. Vulnerability facton' for eastem IJS winter flounder by age", adjusted for discard mortality of undersind fish vulnerable to the commercial (60% of total landings) and spon (40%) fisheries, according to fhhing regulatims in effect for the periods listed. Commercial Sport Total fishery Period 1 2 3 4 5+ 1 2 3 4 5+ 1 2 3 4 5+ 51981 0.03 0 36 0.60 0.60 0.60 0.06 0.24 0.40 0.40 0.40 0.09 0.60 1.00 1.00 1.00 1982 0.00 0.36 0.60 0.60 0,60 0.06 0.13 0.40 0.40 0.40 0.06 0.49 1.00 1.00 1.00 1983 84 0 00 030 0.60 0.60 0.60 0.06 0.13 0.40 0.40 0.40 0.06 0.43 1,00 - 1.00 1.00 1985 87 0.00 030 0.60 0.60 0.60 0.06 0.06 0.40 0.40 0.40 0.06 0.36 1.00 1.00 1.00 1988 92 0,00 0.12 0.57 0.60 0.60 0.06 0.06 0.40 0.40 0.40 0.06 0.18 0.97 1.00 1.00 1993 0.00 0.04 0.42 0.56 0.60 0.06 0.06 0.40 0.40 0.40 - 0.06 0.10 0.82 0.96 1.00 2 1994' 0 00 0.01 a25 0,50 0.60 0.06 0.06 0.30 0 40 0.40 0.06 0.07 0.55 0.90 1.00
- Rese factors assume discard monatity at 50% the nominal F rate for fish caught by commercial gear and at 15% of the nominal F rate for all undersized fish caught by anglers (CT DEP estimates; P. Ilowell, Old Lyme, CT, pers. comm.).
l
- Re notadon 5+ refen to fish that are age-5 and older.
l ' Bued on ngulations proposed for implernentadon by the DEP at the time of preparadon of this report. WinterFlounder 159 1
(NUSCO 1987); selection curves for ll4-mm (4.5- protective regulations, the effect of commercial fish-in),127-mm (5-in),'and 140-mm (5.5-in) trawl mesh ing on ages-1 and 2 has been or will be greatly dimin. codends provided by the DEP; and a discard mortality ished and many age-3 and 4 nsh should be protected as rate of 50% for undersized nsh. The sport fishery was well. The derivation of the equivalent mortality rate estimated to take 40% of the total catch, having a IMP was given in NUSCO (1992a) and is an addition-discard mortality rate of 15% The values of F used in -al small (0.01) component of mortality added to F - the simulations were stepped up from 0.40 in the during the years of MNPS operation. Other data, .1960s to a peak of 1.30 in 1991 (Fig. 6), which rates, and inputs to the SPDM are summarized on reflected the recent historical increase in fishing and Table 4 and include the number of age-classes, age. the current high exploitation of winter flounder. The specine rates of maturation, natural mortality, average value of F was subsequently reduced to meet a targeted weight and fecundity at age, the three porameter SRR rate of 0.50 by 2001. Although the Atlantic States estimates, February water temperature statistics, and Marine Fisheries Commission management plan for other specific factors for each simulation. inshore stocks of winter flounder (Howell et al.1992) Conditional mortality rates for larval entrainment calls for a further reduction in F to about 0.43, the (ENT) from 1984 through 1993 used in SPDM simula-perhaps more realistically attainable value of 0.50 was tions under actual operating conditions were estimated used for all remaining years after consulting with DEP directly using the mass-balance calculations described staff (V. Crecco and P. Howell, DEP Division of above. Values of ENT determined for other years were Marine Fisheries, Old Lyme, CT, pers, comm.). The varied stochastically. An annual value of ENT was effect of the changing Hshing rates on partially vulner- chosen from the range of values determined from the - able fish is seen in Figure 7. As a result of more mass-balance calculations for full MNPS three-unit
^
1.4 - c- : : 2 - l m , 3 1.2 - ; ; c_- ~ W r
$ 1- f f
$ - l l F i! :
g 0. 8 - ; ; O - O 0.6 - . E : : se - . . a , ,
$ 0.4 - { 3 unit operation h - l l
= : :
g 0.2 - ; . l : 50 , , t e . , 0, , , , , r , , , , , , , , , , , , , , , 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 20GO YEAR l Fig. 6. Ilistoric and projected annual mortality rate due to fishing (F). as determined in consulation with the CT DEP, plus a I small (0.01) component accounting for impingement mortality (IMP) at MNPS as implemented in the SPDM simulations. 160 Monitoring Studies.1993
i 1.4 -
# 1.2 -
G \ r g i m . . O . 0.8 - } 9 . E O u- 0.6 - ' '.'. Age-4 O ' 0.4 - ,
!E 0.2 -
~~~
Age 2 N '. . . ........... Age ,3 , , , , , , , , , , , , , , , , ,
~
Age-1
'i\ [\
0, , , , , , , , , , , , , , , , , , , , 1960 1970 1980 1990 2000 2010 2020 2030- 2040 2050 2060 Year Fig. 7. Estirnated reductions in F (including discard mortality) for age-1 through 4 winter flounder as a result of actual or planned regulations imposed by the CT DEP on the winter flounder commercial and sport fisheries. operation. This was done by resampling with replace- water flow rates calculated for 1971-93 wen: re-used to ment using uniform probabilities to randomize the predict entrainment for 1994-2025 by resampling the process. These estimates were calculated under the . historic flows with replacement using uniform proba-assumption that all three units used cooling water bilities to randomize the process. This approach pumped at maximum capacity (11.1 x 106m day *3). assumed that the existing 23 year record of MNPS The selected value of ENT was then scaled by both the operation adequately described the operational vari-number of units in operation in a particular year ability expected at the station in the future. Except (Table 1) and the fractions of cooling-water flow for those cases where randomly chosen values for a actually used during the annual March-May larval year had all three units operating near 100% capacity, winter flounder season (Table 5). MNPS cooling- annual values of ENT used in the simulations were water use was known for 1976 through 1983 and less than the theoretical maximum under full three-actual flow values were used to scale the randomly unit operation. . . i
- selected value of ENT. Because no data were available Simulation of; MNPS impact. The simula-during 1971-75 for Unit 1, flow values for these years tion output consisted of a time-series of annual stock were estimated from net electrical generation records. sizes generated under a specified set of population Estimates for 1972 and 1975, years in which the unit parameters and conditions (including random variabili- - apparently operated near maximum capacity, were - . ty) that constituted a scenario. All model runs consis-normalized to the value for 1987, the year of maxi- ted of 100 replicates of the 1960-2060 stock projec-mum flow for the Unit I time-series; other years were tion series. The final population projection resulted scaled accordingly. Since the simulation time-series from averaging these identically generated 100 repli-extended to 2060 (including a recovery period follow- cate time-series, except for the random components ,
- ing the end of MNPS operation), historic cooling- used to compute annual fish survival rates." It was WinterFlounder 161 l
.J l
TADLE 4 Data, rates, and other inputs used with the Niantic River winter nounder population dynamics simulation model Modelinput Value used or available Number of age-classes in population 15 Earliest age at which all females are mature 6 ,
~I Fraction mature, mean wt (Ibs), and mean fecundity by age. q Age-1 females 0 0.011 0 .'
Age 2 females 0 0.125 0 Age 3 females 0.08 0,554 223,735 Age-4 females 036 0.811 378,584 Age 5 females 0.92 1.089 $68,243 ! Age 4 females 1.00 1377 .785,897 Age-7 females 1.00 1.645 1,004,776 Age-8 females 1.00 1.873 1,201,125 Age-9 iemales 1.00 2.057 1,366,951 Age 10 females 1.00 2.203 1,502,557 Age !! females 1.00 '2304 1,598,597 Age 12 females 1.00 2.390 1,682,208 Age 13 females 1.00 2.461 1,754,800 Age-14 females 1.00 2 516 1,809,000 Age 15 females 1.00 2.552 1,845,800 Age after which annual mortality is constant 3 Instantaneous mortality rates M and F at age-I 0.50 0' Instantaneous mortality rates M and F at age-2 035 0 Instantaneous monality rates M and F at age 3+ 035 0 Initial num'oer of female spawner: 66,988 6 Mean fecundity of the stock (eggs per female spawner) 871,0006 a from the three-parameter SRR for the virgin (F = 0) stock (numbers of fish) 5.42' S from the three-parameter SRR 2.523 X 10.s e from the three pararneter SRR 0.412 Mean February (1977-89) water temperature (*C) 2.48 standani deviation 1.09 minimum temperature 0.36 maximum temperature 4 02 Number of spawning cycles (years) to simulate .100 Number of simulation replicates per run 100 Fraction of age-O group entrained at MNPS (i.e.,irnpact) 0.00d
- Values are entered here only when mortalities remain constant donng au the spawning cycles or years simulated. Zerr, values direct the model to get a detailed schedule of mortalities frcru an auxiliary input file set up as a look-up table (see Resuhs and Discussion),
b Corresponds to the unfished stock at equilibrium (see Table 32 in Resulu and Discussion).
- 1adirectly calculated from life history parameters (see Stock recruiunent relationship in Resuhs and Discussion).
d A sem simulates a non impacted stod; otherwise the conditional mortality due to entrainment is used. l l previously concluded that 100 replicates were suffi- geometric mean of the replicates was computed. All cient, given the amount of variability present in stock projections are given in units of spawning: SPDM simulations (NUSCO 1990), Thus, the biomass (lbs) because overfishing criteria often rely Monte Carlo sample size was set to 100 and the on measurements of biomass and assessments based i 1 162 Monitoring Studies,1993 i
TADt15. Annual average cooling. water tiow and percent of norrdnal maximum flow at MNPS Units I through 3 during the March May winter flounder larval entrainment season from 1971 through 1993. Unit 1 Unit 2 Unit 3 Nominal flow at 100% capacity: 29.18 m'sec4 37.62 m'sec4 61.91 m3 sec.: Fracthm of total MNPS flow: 0.227 0.292 0.481 March.May March.May March May average flow % of nominal average flow % of nominal average flow % of nominal Year
- in m'.sec 8 muimum in m8 sec4 maximum in m s.sec4 muimum I971 -
67.41 - - - - 1972 - 99.64 - - - - 1973 - 3181 - - - 1974 - 8330 - - - - 1975 - 99.64 - - - 1976 25.39 90.80 29.16 80.83 - - 1977 27.61 98.73 24.61 68.20 - - 1978 17.48 62.53 18 91 52 41 - - 1979 17.18 61.44 21.48 59.53 - - 1980 27.60 98.70 31.75 88 01 - - 1981 1.52 5.43 33.98 94.18 - 1982 27 60 98.70 32.33 89A1 - - 1983 26.79 95.83 30.90 85.63 - - 1984 13.88 49.61 35.83 99.31 - - 1985 27.86 99.64 16.40 45.45 - - 1986 27.21 9125 3689 98 51 49.82 80.48 1987 29 01 99A0 36,99 98.32 47.12 76.12 1988 28C4 98.81 32.83 87.27 $5.58 89.78 1989 13.85 47.46 24.72 65.72 51.33 82.91 1990 27.55 94.39 33 28 88.48 48.71 78.68 1991 10.79 36.98 32.29 85.83 38.65 62.44 1992 25.11 86.06 28.50 75.75 51.10 82.55 1993 27.78 95.21 33.52 89.10 58.82 95.00
- No recordi of cochng water flow were avasable for 197175 Net electrical generancn records were used to estimate flow, with values for 1972 and 1975 normahzed to the value lor 1985 (matimum of the Unit 1 tirne serrs), an6 IV71,1973, and 1974 adjusted accordingly.
on biomass tend to te more conservative dian those three types of anthropogenic mortality (F, IMP, and based on fish nurnbers, Furthe:Tnore, larval entrain. ENT) occurred. The first time series with no fishing ment effects result in long term stock reductions or plant effects was the reference series against which which can be quite different depending on whether the the potential for recruilment failure was evaluated stock is expressed as fish numbers or as biomass, when the largest reductions of stock biomass occurred A complete simulation of MNPS impact consisted during any of the odier simulations. The second time-of three model runs, which provided a set of time- series represented the most likely trajectory of the series Eenerated under the same scenario, but with exploited stock without MNPS operation, ne third different combinations of F (plus IMP) and ENT. time-series was the expected stock uujectory when the
- Rese model runs were designed to simulate the natu. 'onditional mortality rates corresponding to ENT and ral variability of the theoretical unfished stock (i.e , IMP were added to the fishing mortality simulated for with no fishing or plant operational effects); the the baseline. This last time-series was the basis for reduced stock biomass when subjected to fishing quantitatively assessing MNPS impact on the Niantic mortality (i.e., the baseline time-series without River winter flounder population.
MNPS effects); and the expected biomass when all Winter Flounder 163
I 1 l l l l l Results and Discussion luh winter f1Ounder ! Seawater temperature ulative anmtalabundance l On the basis of the coefficient of variation (CV), The 1993 adult winter flounder survey in the I monthly mean seawater temperatures recorded at Niantic River began on February 16 (Table 8). Ice MNPS were rnost variable from January through conditions and storms in 1993 were among the worst i March (CV = 32-47%; Table 6). Winter 11ounder of the 18-year history of this program and resulted in spawning and early larval development occur during reduced sampling during 3 of the survey weeks. Only 1 these months. Temperatures were most stable (CV = 21 tows were completed during the second week of 1 4-6%) during summer, when collections of winter sampling (February 22-26),3 during the third week flounder were dominated by young and other immature (March 15), and 25 during the fifth week (March 15- ;l fish. The annual mean temperature for 1993 was 19); the weekly average for the other 5 weeks of 11.69'C, slightly warmer than the overall average of sampling was 48 tows per week. The total of 288 11.50*C since 1976. Mean water temperature during tows in 1993 was the smallest since 277 were com. winter (3.79'C; Table 7) was the coldest since 1989, pleted in 1987 (Table 9). As found during the past reflecting episodes of inclement weather discussed few years, most adults were concentrated in several below in conjunction with the adult spawning sur- areas, including the northern section of the upper river veys. Ilowever, mean temperatures during spring arm and in Keeny Cove (Fig. 2). Fewer females (11.03*C) and summer (19.91*C), the periods for late spawned earlier in 1993 compared to recent years, larval development, metamorphosis, and development when proportionately more females were spent, prob-of young, were warmer than the respective 17-year ably because of the colder weather this year Neverthe-averages of 10.89'C and 19.61*C. less, spawning was completed by mid-March as the percentage of egg-bearing females larger than 26 cm declined from about one-third of the females examined during the first few weeks of sampling to about 5% TABLE 6. Monthly and annual mean seawater temperature (*C) from January 1976 through December 1993 as calculated from mean daily , water temperatures recorded continuously at the intakes of MNPS Units I and 2. Year Jan Feb Mar Apr May Jun Jul Au8 Sep Oct Nov Dec Annual mean 1976 3.65 331 4.81 7.55 10.75 15.!! 18.29 19.60 18.93 15.04 9.28 4.73 10.90 1977 0.67 036 2.85 5.66 10.72 14 92 19.08 2033 19.41 15.58 12.18 6.72 10.84 1978 3.01 1.09 1.67 4 85 9.10 14.24 17.68 19.82 19.24 16.14 12.47 7.74 10,64 1979 4.53 1.48 335 5.93 10.50 15.57 18.84 20.91 20.05 15.99 12.41 8.60 11.57 1980 5.16 238 1 80 638 10.44 14.76 18.44 20.23 20.16 16.07 10.25 5.73 11.10 1981 1.06 2.63 336 6.40 10.19 15.48 19.51 20.86 19.94 14.75 11.07 6.29 11.01 1982 2.20 1.56 3.04 5.41 10.06 14.16 17.98 21.10 20.01 15.95 12.47 8.97 11.13 1983 5.58 3.74 4.55 7.07 10.50 15 05 19.10 19.17 20.57 17.37 12.57 7.90 11.98 1984 4.84 4.02 3.98 6.58 10.84 15.53 18.90 20.60 19.52 16.41 13.o4 9.07 11.97 1985 4.*36 236 4.17 7.02 10.95 14.99 18.98 21.24 20.44 17.46 13.14 7.95 11.98 1986 4.62 338 4.11 7.25 1132 15.99 18 83 20.62 18.80 16.53 12.43 8.19 11.89 1987 5.28 3.27 4.53 7.51 11.26 15.91 19.19 20.47 1930 15.70 11.10 7.16 11.78 1988 2.65 2.67 4 49 7.01 10.67 14.69 1830 2031 18.86 14.91 11.41 7.20 11.12 1989 4.49 3.24 3.67 6.21 10.59 15.25 18 95 2031 19.92 15.83 12.25 4.87 1134 1990 3.60 4.28 4.% 6.84 10.73 14 93 18.65 20.80 20.23 17.74 12.47 9.12 12.08 1991 5.72 4.76 5.61 8.11 12.26 16.61 19.53 20.48 19.99 17.11 12.00 8.17 12.59 1992 5.20 3.68 4 42 6.80 10.72 15.42 18.43 19.62 19.20 15.17 !!.12 7.28 11.45 1993 5.09 3.10 3.12 6.09 1137 15.64 18 96 20 88 19.88 1535 11.73 8.47- II.69 OveraD mean 3.99 2.85 3.86 6.63 10.72 15.24 18.76 20.40 19.67 16.06 11.84 7.45 !!.50 CV (%) 47 46 32 20 15 10 6 4 5 10 15 27 5 1 164 Monitoring Studies,1993
TABLE 7. Seasonal
- rnean seawater temperature ('C) for 1976 through 1993 as c.alculated from mean daily mater temperatures determined by continuous recorders at the intakes of MNPS l' nits I and 2.
Yeat Winser Spring Summer Fall 1976 3.94 11.14 18.94 9.69 1977 132 10.72 19.61 11.49 1978 1.95 9 40 18.91 12.11 1979 3.17 10.67 19.93 1233 1980 3.47 10.53 19.61 10.69 1981 2.34 10 69 20.11 10.70 1982 2.29 9.88 19.69 12.46 1983 4.65 10.87 19.61 12.61 1984 4.29 10.99 19.68 12,84 1985 3 67 10.98 20.22 12.85 1986 4 06 11.52 19.43 1238 1987 4.40 11.56 19.66 1132 'l 1988 3.28 10.79 19.16 11.17 1989 3.82 10.68 19.72 10.97 l 1990 4.28 10.83 19.89 13.16 1991 5.38 1232 20.00 12.48 1992 4 45 10.98 19.08 11.19 1993 3.79 11.03 19.91 11.85 Overall mean 3.59 10.89 19.61 11.79 CV (%) 44 35 6 34 , I
- Winter is January through March spring is April through June, summer is July through September, and fallis Octr>ber through December.
TAILLE 8. Annual Niantic River winter flounder
- population by the end'of March and early April (Fig. 8). As a i surveys during the spawning seascri from 1976 through 1993.
result, the spawning survey ended on April 7. He mmber of median CPUE in 1993 for winter flounder larger than Year Dates sampled weeks sampled 15 cm was 1.9 (Table 9; Fig. 9). This value is only about 30% of the CPUE of 6.2 for 1992, which had 1976 March 1 - April 13 7 been the smallest CPUE on record, in fact,in 17 ; 1977 March 7 - April 12 6 tows during 1993 (about 6% of the total), no winter
' "^ '
lh ' Nc'h 12. Aprit l7 fl under of any size were taken. The winter flounder 1980 March 17 April 15 5 taken during 1993 were, on the average, larger than 1981 March 2 April 14 7 those collected during the past 3 years (Fig.10), or 1982 February 22 - April 6 7 during any previous survey Most fish taken during 1983 February 21 Apn] 6 7 1993 were larger than 32 cm and, thus, more vulnera-
* ' ^Pnl 4 8 3]4 r' ry Ap,, 9 ble to continued high rates of fishing. The peaks seen in the annual length-frequency distributions from 1990 1986 February 24 April 8 7 1987 March 9. Apnl 9 5 through 1993 were probably fish from the relatively 1988 March 1 April 5 6 strong 1988 year-class, since recruitment has been 1989 February 21 April 5 75 poor in more recent years. This can be better i!!astrat- - 1 l 1990 Fehnaary 20 April d 7 ed by comparing the annual standardized catch of.
19 Fe 8 fema es for 1990 through 1993, which shows relative - 1993 February 16- April 7 3 abundance from year to year by size (Fig.11). The decline in winter flounder abundance during most
- Minimum size for marking was 15 cm during 1976-82 and recent years, particularly among fish smaller than 32 20 cm thereafter, 1.imited samphng during week 2 because of ice formation.
cm, was even more pronounced when catches from Almost no samphng during week 3 and Imuted samphng during par 1 weeks 2 and 5 because ofice and weather conditions. peak abundance for this series),'1985 (after winter j J WinterFlounder 165 . l
.-._. .. _ . . . . m 35-es 30 '
93
- u. ,
h 25- ," s 5 90 - o 92 , s
$ 20; 89 * . , s
;s ,3; -"N" . ' s .
b 88 s 0 g 10- ', o s y
- s
, 9 3. , . -"
5-, 5 = y o , 0-- FEBRUARY MARCH APRIL Fig. 8. Weekly percentage of Niantic River female winter flounder larger than 26 cm that were gravid during the 1987 through 1993 adult population abundance surveys. Data from weeks in 1993 during which few or no tows were taken were not included. TAllLE 9. Annual 9.1 m otter trawl adjusted median CPUE' of winter flounder larger than 15 crre taken throughout the Niantic River during the 1976 through 1993 adult population abundance surveys. Tows' Adjusted Median 9M confidence Coefficient Survey Weeks acceptable number of CPUE interval for of year sampled for CPUE' tows used* estimate skewnessd median CPUE . 1976 7 143 231 37.0 34.2 - 39.6 3.01 1977 6 184 228 23.1 20.4 - 26.4 1.95 1778 6 137 159 21.0 18.8 27.0 - 1.83 1979 5 122 145 33.6 25.5 39.5 1.52 1980 $ 112 145 36.0 30.0 43.2 1.68 1981 7 182 23] $1.6 45.6 - 56.4 3.50 1982 5 118 150 42.6 42.6 - 46.0 1.14 1983 7 232 238 30.2 26.2 31.8 0.85 1984 7 245 287 16.8 15.8 - 18.0 1.17 1985 7 267 280 14.8 14.2 15.4 1.33 L 1986 7 310 336 10.2 9.7 11.1 1.47 1987 5 233 270 14.8 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 13.3 1.08 1990 7 320 343 9.6 8.7 -10.3 3.04 1991 6 302 330 12.3 11.1 13.4 2.62 1992 7 380 406 6.2 5.66.6 1.29 1993 7* 288 392 1.9 1.7 - 2.6 1.92 ' Catch per standardized now (see Materials and Methods).
- Mostly age.2 and older fish.
Only tows of standard time or distance were considered and effort equalued among weeks. d Zero for symmetrically distributed data.
- Because of low effort, data inxn the third week of sampling not used for the computation of CPUE.
166 Monitoring Studies,1993
~;
g trawl survey indices also indicated very low levels of F abundance in recent years. so
@ l y so- y\,
Absolute abundance estimates 40-b - Mark and recapture data were used with the Jolly h 30 - (1965) model to determine absolute abundance esti-5 20- mates of fish larger than 20 cm (N); estimates of
- A survival (@), recruitment (B), and sampling intensity 6 10- M (p) were also generated. Because of the decline in !o \ population size, only 972 winter flounder 20 cm and O
- is ' is ' e'o ' e'2 ' 84 ' ' e's ' 8'8 'do'd2' larger were marked with a freeze brand this year, wluch YEAR was well below the total branded in any other year since 1983 (Table 10), The total of 154 previously Fig. 9. Annual median CPUE (12 standard erro 3)for marked fish that were recaptured in 1993, however, Niantic River winter flounder larger than 15 cm from was not disproportionately low, Most (n = 109; 71%)
1976 through 1993. of the recaptured fish had been marked in 1992. Addition of recapture data from 1993 resulted in an flounder had decreased from peaks observed during the increase for the 1991 estimate of N = $9,165 reported early 1980s), and 1990 (Fig.12). NMFS (1993) in NUSCO (1993) to 62,743 (Table 11), The initial reported that combined sport and commercial fishery abundance estimate for 1992 of about 12,178 winter landings for the Southern New England Middle Atlan-flounder was only 19% of the 1991 population esti-tic stocks of winter flounder declined 35% from 1991 mate, although this value will likely increase to 1992 and were at a 14 year low, NMFS research 7-93 6-W - 92 g # ' o 5-gj <s S e i c . < 90
' 4- , .-
i Z !, % y ' / .., %. s b~ t; i \ i
;.~ l l.
't
~
2- [ V.,'g ,A, l' , '. ., h x : w -
'. a ,
o . . Q- ' ,e t s g 0 rr r rrr, r i i i e i iiiii r iiii,,,,ivi,,iiii,,, 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 30 37 38 39 40 41 42 43 44 45 x ,,iiir - LENGTH (cm) Fig.10. Comparison of percent lengstofrequency distributions of winter flounder 20 cm and larger taken in the Niantic River during the spawning season from 1990 through 1993. WinterFlounder 167
4 m 70- 91 wJ 2 60-. w tL tL O 50-1 O o 40-O W . 92 # 5 30- i ~' C s J g , li 9 0 , ./ . ..(. ../ , . i 5 20- l'.. . ' . !' ~' ' \ 'r~'.+<.., H . l 9 3 .l % m : . : \. a . : .
< 10- .
.5 g -
z : s
< 0 e, 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 LENGTH (cm)
Eg 11. Comparison of annual standardized catch by length of female winter flounder 20 cm and larger taken in the Niantic River during the spawning season from 1990 through 1993. m 180-d 82 2 1602 W tL u, 140-O I o 120-V O 100 i O w
$ 80-e o 60-z 85
$ 40-e $
s . a . . , , .,~~- 99.".., ......, ~ > g 20; ;,*....'...,.,,....,-
.. ,a
. . ~ -
2 ;- . . . . 4 , OA . ,i ~. . r,
~
> > . , , , , , , , , , , , , , T. .
20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 LENGTH (cm) Fig.12. Comparison of annual standardized catch by length of female winter flounder 20 cm and larger taken in the Nian'.ic River during the spawning season in 1982.1985.1990. and 1993. ! 168 Mo-!:nring Studies,1993 I
TABLE 10. Mark and acapture data from 1983 through 1993 used for estimating abundance of wmter flounder larger than 20 cm in the Niantic River dunng the spawning seasort. Total Total not Number Total Survey number previously marked and number Nurnber of fish marked in given year recapured during annual surveys: year observed marked released recaprured 83 84 85 86 87 88 89 90 91 92 1983 5.615 5,615 5,615 0 - 1984 4,103 3,973 4,083 130 130 1985 3.491 3,350 3,4Cr7 141 47 94 i 1986 3,031 2,887 3,010 144 23 45 76 1987 2,578 2,463 2,573 115 2 13 27 73 1988 4.333 4,106 4309 227 7 22 31 63 IN 1989 2,821 2,589 2,752 232 2 11 9 33 32 145 1990 2.297 '.,135 2,275 162 1 7 4 15 14 38 83 1991 4,333 4,067 4324 266 1 5 4 12 27 33 54 130 1992 2,346 2,119 2,336 227 0 0 1 2 3 21 20 $3 127 1993 984 830 972 154 0 0 0 1 0 4 4 15 21 109 TABLE I1, Estimated abundance
- of winter flounder larger than 20 cm taken during the spawning season in the Niantic River from 1984 +
through 1992 as deterrnined by the Jolly (1965) mark r.J recapture model. Abundance Standard Probability Standard estimate error of 95% G of survival error 95 % O Year (N) N forN (c) of o for@ 1983 0.328 0.040 0.251 0.405 1984 57,706 8,370 41,300 74,112 0.538 0.065 0.430 0.686 1985 79,607 10,851 58,338 100,876 0.361 0.041 0.281 0.442 1986 49,287 6.229 37 578 61,497 0.650 0.067 0.518 0.781 1987 75,592 9,746 56,490- 94,695 0.596 0.062 0.474 0.719 1988 66,607 7,247 52,404 - 80,011 0.462 0.049 0.366 0.558 1989 42,534 4,865 32,998 52,069 0.390 0.042 0.308 - 0.472 1990 33,243 3,861 25,675 - 40,810 0.863 0,105 0.657-1.068 1991 62,743 7,872 47,314 -78,171 0.149 0.023 0.104 0.194
- 1992 12,178 1,8 44 8,565 -15,791 ;
Mean 53,277 2,730 48,515 58,(M0 0.484 0.013 0.459 - 0.509 Sampling Standard Annual Standard intensity error of 95% C recruinnent error 95% G , Yest (p) p. forp (B) of B for B . 1984 0.071 0 0103 0.050 0.091 47,428 9,083 29,626 65,231 198% 0.044 0.0060 0.032 0.055 20,550 ' 5,226 10,307 30,794 1986 0.061 0.0078 0.046 - 0.076 43,585 8,464 26,995 60,176 . 1987 0.034 0.0044 0.025 0.043 21,525 6,371 9,038 34,011 1988 0.065 0.0071 0.05I . 0.079 11,762 3,739 4,434 - 19,091 1989 0.066 0.0076 0.051 - 0.081. 16,695 3,114 10,592 22,798 1990 0.069 0.0081 0.053 0.085 34,087 5,772 22,774 -45,400 1991 0.059 0.0087 0.052 0.036 2,839 1,123 638 5,040 1992 0.192 0.0292 0.131- 0.249 Mean 0.074 0.0040 0.066 0.082 24,809 1,175 22,507 -27,111 1
- Estimates may vary from those reported in NUSCO (1993) because of mark and recapure data added from the 1993 adult winter flounder population survey.
WinterFlounder 169
somewhat as additional marked fish are recaptured in future surveys. The standard errors of N given in g g 2o " Absolute abundance l
'go y Tabic 11 are correlated with N because of the particu- o .A, .,
lar form of Jolly's variance formula. Therefore, the E '87 / i. / '" 70 95% confidence intervals computed are generally considered unreliable as a measure of sampling error. l ; . i., 'j k'
., ,.'. -60 z Es 122 \ /\ - 50 5 to:
' ~
except at very high sampling intensities (Manly 1971; ' Roff 1973; Pollock et al.1990). Sampling intensity CPUE N..*s/ -do < g ei ;g (p), or the probability that a fish will be captured, was g 6-i m
- 20 4 relatively high (0.192) during 1992 in comparison to $ % i -
other years (0.034 - 0.071). This was probably the result of intensified sampling on a smaller population g g 2-0' 4 l g', ,5 g's s'7 e's s'9 do d1 d2 of fish that were concentrated m relatively few areas of s yg j the Niantic River, which may have introduced some bias into the estimates if interannual catchability Fig.13. Comparison between the estimates of absolute changed. Sampling intensities of about 0.10 are abundance in thousands of winter flounder larger than 20 recommer:ded to obtain cliable and precise estimates em in the Niande River during the spawning season of population size and survival rates with the Jolly (dashed line) and the conesponding median CPUE (solid model (Bishop and Sheppard 1973; Nichols et al. line) from 1984 through 1992. 1981). Ilightower and Gilbert (1984) found that low sampling effort may give acceptable estimates if population size is relatively large and the number of and Gilbert 1984). If the estimate of o was correct,it marked animals is also relatively high. However, would imply an annual fishing rate equal to about 1.5, Gilbert (1973) and Carothers (1973) reported that N assuming a natural mortality rate of 0.35. As for was underestimated and had low accuracy when sam- other values based on only 1 year of recapture infonna-pling intensities were low (5-9%), regardless of popula, tion, estimates of 4 and B may change considerably don size or number of fish marked. Loss of marks with the addition of data from the next winter flounder because tags were not observed, or from mortality, survey. Nevertheless, the low estimates of B appeared also requires increased sampling effort. Other sam- to accurately reflect low recruitment corresponding to pling errors, model assumptions, and biases inherent weak year-classes that have been produced in recent in the Jolly model that could have affected these yeaa estimates t Because of the reasonable correspondence between
- discussed in NUSCO (1989) and Pollock et al. (1990). Nevertheless, when set to a the median trawl CPUE index and the Jolly abundance similar scale, CPUE and Jolly abundance estimates estimate, the annual standardized catches of all fish appeared to track each other well (Fig.13), even larger than 20 cm for 1984 92 were compared to the though the lauer may be subject to considerable error, t tal abundance estimates from the Je u y model. In The two abundance indices are significantly correlated Previous reports, the relative numbers of females and (Pearson correlation coefficient = 0.85; p = 0.0062). eggs Produced each year were assumed to represent, Thus, based on a median CPUE of 1.9, absolute conservatively, about 3.5% of the absolute values abundance of winter flounder in 1993 was likely less (range of 2.7 4.5%) and a multiplier of 28.571 (the than 10,000 fish. In contrast, by extrapolation the ratio of 100 to 3.5) was used to scale abundance abundance in 1981 could have been greater than indices to absolute numbers. The 1992 annual stan.
200,000 winter flounder. dardized catch index was 8.4% of the corresponding The estimate for survival (c) of fish from 1991 to total population estimate, increasing the geometric 1992 was particularly low (0.149; Table 11), as was mean of the series to 3.8%. Because of uncertainties the estimate of recruitment (B = 2.839). Although associated with the latest population estimate, the - reflecting apparent trends for the Niantic River popula- 3.5% value continued to be used in scaling absolute tion of winter flounder, estimates of these parameters abundance indices. This adjustment also assumed that are considered to be less reliable than those of abun- the ratios of annual standardized catch to absolute dance when using the Jolly model (Bishop and abundance for 1977 through 1983 would have been Sheppard 1973; Amason and Mills 1981; Hightower similar to those for 1984-92, had estimates of abso-lute abundance been available for the earlier period. 170 Monitoring Studies,1993
Spawning stock size and egg production observed females were mature (NUSco 1988a). This is comparable to L50 estimates of 28.3 and 27.6 cm The size of the Niantic River winter flounder t emale reported for Massachusetts waters by Witherell and spawning stock is used in various assessmen;s of Burnett (1993) and O'Brien et al. (1993), respectively. MNPS impact. The annual standardized catch of In recent years, most spawning in the Niantic River female spawners (an index of spawning stock size) and was completed by late March or early April as relative-the production of eggs were determined from available ly few gravid females were found afterwards (Fig. 8). data on sex ratios, sexual maturity,' and fish During most years, ice in the upper river prevented the length. frequencies. The sex ratio of winter flounder start of field work in January or early Febmary, so larger than 20 cm during the 1993 spawning season in approximately two-thirds of the females examined . the Niantic River was 1.47 females for each male during late February and early March had spawned (Table 12), the largest ratio found since 1988 and before sampling began. Apparently, most females somewhat higher than the 17 year average of 1.34. spawned relatively early in mcent years, as few gravid Ratios of 1.50 to 2.33 in favor of females have been fish were taken, particularly after mid March. Spawn-reported by Saila (1962a,1962b) and by Howe and ing was likely correlated with water temperature. In Coates (1975) for other winter flounder populations in relatively cold years (e.g.,1977 and 1978) proportion-southern New England. Witherell and Bumett (1993) ately fewer females spawned during the earlier portion also reported greater proportions of female winter of the survey, compared to warmer years (e.g.,1989 flounder in Massachusetts waters, particularly in older and 1992) when more fish were spent at the beginning age-classes. They believed that males likely have a of sampling. hip',er natural mortality rate, based on evidence of For each year, the proportion of females considered earlier ages of senescence reponed for males by Burton to be mature for each 0.5-cm length increment was and Idler (1984). used with the annual standardized catch of females to obtain relative annual abundance indices for female TABLE 12. Female to male sex ratios of winter flounder taken spawners. Mature females comprised approximately during the spawning season in the Niantic River from 1977 one-third to one-half of each yer.rly total, with relative ' ** h I " numbers of female spawner: ranging from a low of Measured 274 in 1993 to 2.752 in 1982 (Table 13). Varying Year All fish captured fish > 20 an sex ratios and differences in percent maturity due to changes in length-frequency distributions somewhat in7 1.03 1.26 affected average fecundity, which was low during the
}", 8 1980
$7 2.66 2.03 late 1970s when smaller fish were more abundant, but increased during recent years because of increasing 1981 1.42 1.61 proportions of older and larger fish. De relative index 1982 1.16 1.50 of total egg production reflected female stock abun-1983 1.52 1.52 dance and length distribution and was greatest from f9y lj j 1981 through 1983 because of peak population abun-1966 0.92 0.92 dance and moderate average fecundity. Average fecun-1987 0.78 0.78 dity estimates for 1992 and 1993 were the highest of 1988 1.50 1.50 all yean, because of an older age structure and relative-1989 1.32 132 ly poor recruitment from incoming year-classes that
[ 'jj 12 {j would have comprised the majority of the spawners. 1992 1.26 L26 Absolute estimates of spawning females and associ-1993 1.47 1.47 ated egg production were generated by multiplying corresponding relative numbers by 28.571 (see Abso-ccometric mean 133 134 lute abundance estimates, above). Female stock size - l was between approximately 7,821 and 78,629 fish, ! while estimates of annual egg production ranged from ) ne rate of spawning was determined by observing about 6.4 to 45.6 billion (Table 13). The total num. ! ber of female spawners was used as an estimate of 4 weekly changes in the percentage of gravid females parental stock size for the SRR, which is discussed larger than 26 cm, the size at which about half of all WinterFlounder 171 i
l I TABl.,E 13. Reladve and absolute annual standardized catch of female winter flounder spawners and corresponding egg produeden in the ! Mantic River frorn 1977 through 1993. l I Relative index Reladve index Survey of spawning % mature Avcrage of total Total female Total egg year females
- females
- fecundity' egg productiond stock size' production (X 10'f 1977 884 36 446,336 394.6 - 25,2fo 11.274 l 1978 1,412 51 508.096 717.5 40,349 20.501 ;
1979 1,120 37 478,108 $35.3 31,989 15.294 j 1980 903 34 469.976 4243 25,793 12.122 l 1981 2,669 44 518,275 1,383.1 76,248 39.517 1982 2,752 49 580,227 1,596.8 78,629 45.622 1983 1,869 46 578,845 1,082.0 53,406 30.914 1984 871 40 575,822 501.6 24,886 14.330-1985 928 43 609,215 565.2 26,510 16150 1986 655 42 667,065 436.7 18,704 12.477 1987 852 39 624,085 531.6 24,339 15.190 1988 1,279 53 677,910 866.9 36,539 24.770 1989 984 52 728,042 716.2 28,108 20.464 1990 579 42 639,541 370.4 16.546 10.582 1991 1,061 47 603,132 639.6 30,300 18.275 1992 534 52 732,317 391.1 !$,260 11.175 1993 274 54 816.885 223.6 7,821 6.389
- Based on proponion of the relative annual standardized catches of winter flounder that were mature females.
b As a proportion of all winter flounder 20 cm or larger.
- Total egg pralucdon divided by the number of spawning females.
d A relative index for year-to-year comparisons and not an absolute estimate of produenon.
- Calculated on the assumpdon that the reladve annual standardized catches were approximately 3.5% of absolute values, below. Egg production was greatest in the early capelin (Mallotus villosus) eggs, removing up to 39%
1980s, but estimates were relatively high in 1988 and of the production. They suggested that invertebrate 1989 as proportionally older and larger females domi, predation on demersal fist. eggs may be an important nated the moderately-sized reproductive stock. Egg regulatory mechanism for population size in marine production decreased to about 10.6 billion in 1990 fishes having demersal eggs, Morrison et al. (1991) because of a decline in female abundance and in their reported high mortality of demersal Atlantic herring average size, increased by about 50% to 18.3 billion (Clupea harengus) eggs in the Firth of Clyde, Scot-in 1991 as the number of spawners increased, but land because of heavy deposition of organic matter decreased again to 11,2 billion in 1992 and to a series resulting from a bloom of the diatom Skeletonema low of 6.4 in 1993, costatum. The decomposing material caused a deple-Comparatively little is known about the egg stage tion of oxygen and egg death due to anoxia, of. winter flounder, Buckley et al. (1991) noted that Skeletonema costatum was one of the most abundant female size and time of spawning affected various of the phytoplankton collected at MNPS during reproductive parameters, including egg size, fecundity, entrainment sampling from 1977 through 1980 and viability. Embryos produced earlier in the season (NUSCO 1981). However, highest densities occurred appeared to have a survival advantage, particularly in summer, after the winter flounder spawning season. over those from smaller fish late in the season. Egg deposition apparently takes place on gravel bars, algal Larval winter flotlnder mats, eclgrass beds, and near freshwater springs in Rhode Island salt ponds (Crawford 1990), Based on Abundance and distribution estimated egg production and abundance of Stage I larvae, egg mortality may be considerable, DeBlois The at parameter of the Gompertz function (Eq. 2) and Leggett (1991) found that the amphipod was used as an index for temporal (year to year) and Callio@ laeviusculus preyed heavily upon demersal spatial (Niantic River and Bay) abundances of winter 172 Monitoring Studies,1993
flounder larvae. Based on the 95% confidence interval Ar nual spatial abundances of the first four larval around the a parameter estimate, larval abundance developmental stages were based on cumulative week-during 1993 in the river (stations A, B, and C com- ly geometric means (Figs.14 and 15), ne abundance ' bined) and the bay (stations EN and NB combined) distribution of Stage 5 was not examined because so was significantly lower than any other in the 11-year few were collected. In instances where this function series (Table 14), In general, annual abundances in did not satisfactorily fit the data, cumulative density the bay varied less than in the river, in 1985,1988, data (the running sum of the weekly geometric means) and 1989, larval abundance in the river was much was used to compare abundances as a surrogate for the greater than in the bay. Although 1993 had the low- a parameter from the Gompertz function. His usual-est abundance in both the river and the bay, no consis- ly occurred when a developmental stage was rarely tent relationship was found between the annual abun- collected at a station (e.g., Stage 1 at stations EN and dances between the two areas (Spearman's rank-order NB or Stage 4 at station A), Cumulative weekly :! correlation coefficient p = 0.455; p = 0,160) during geometric means and the corresponding a parameters j the 11-year period. This lack of relationship may were found to be highly correlated (Speannan's rank-have at least two possible causes, First, if many of order correlation coefficient p = 0.999; p < 0.001) in a the larvae in the bay came from the river, then highly previous study (NUSCO 1989), suggesing that cumu-variabic annual larval mortality rates occurred prior to lative weekly geometric means could be used as an the period when larvae were flushed from the river to alternative index of larval abundance in some cases, the bay. Secondly, the Niantic River may not be the Stage I abundance during 1993 in the river was one only source of larvae entering the bay and this possi- of the lowest during the Il year period of sampling at bility was discussed in detail in NUSCO (1992a, all three stations. A comparison of annual Stage 1 1992b,1993) and will be addressed again later in this abundance among years showed a similar relative section. Larval abundance in the bay since 1976 ranking at the three stations, with 1988 and 1989 appeared to reflect regional-wide trends as annual ranked the highest and 1983,1986, and 1993 the abundance (a parameter) at EN since 1976 was highly lowest. Except for a slightly greater abundance at sta-correlated (Spearman's rank-order correlation coeffi- tion A in some years, annual abundances at the three cient p = 0.651; p = 0.003) with annual abundance river stations have been similar, This indicated a indices in Mount Hope Bay, MA and R1 (Marine somewhat homogeneous distribution of Stage 1 larvae Research,Inc.1992; M. Scherer Marine Research, throughout the river, Because winter flounder eggs are Inc, Falmouth, MA., pers comm.). However, no demersal and adhesive and the duration of Stage 1 is relationship was found between the abundances in the short (about 10 days), the homogenous distribution Niantic River (1984-93) and Mount Hope Bay suggested that spawning was not restricted to any (Spearman's rank-order correlation coefficient p = specific area of the river or, conversely, that the river. j 0.091; p = 0.803). is well mixed. Low abundance in 1983 was panly , TAllLE 14. Larval winter flounder abundances and 95% confidence intervals for the Niantic River and Bay as estimated by the a parameter i from the Compertz function. Year Niantic River Niantic Bay 1983 1,863 (1,798 1,929) 3.730 (3,670 3,791) 1984 5.018 (4,884 5.152) 2.200 (2,088 2,311) 1985 11,924 (11,773 - 12,(Tl5) - 1,801 (1,717 - 1,886) 1986 1,798 (1,726 1.87I) 1,035 (979 - 1,091) 1987 5.381 (5,172 5,589) 1,301 (1340 1,363) 1983 24.004 (23,644 24,364) 1,784 (1,708 - 1,861) l 1989 18,586 (17,965 19,207) 1,751 (1,696 - 1,806) i 1990 5,544 (5,378 5,709) 1,532 (1,474 1,589) ! 1991 4,083 ' (3,973 4,193) 1,444 (1,388 -1,500) 1992 10.646 (10,184 - 11,108) 4,415 (4,214 -4,617) 1993 1,513 (1,470 - 1.557) 459 (391 526) j I l WinterFlounder 173 1
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0 YEAR 83 84 85 86 87 88 89 90 91 92 93 ' 83 84 85 86 87 88 89 90 91 92 93 STATION EN NB l i 1 Fig.15. Cumulative density of each developmental stage of larval winter floundet at the Niantic Bay stations EN and NB . _i from 1983 through 1993. (Note that the vertical scales differ among the graphs). I WinterFlounder 175
-i
attributed to undersampling because of net extrusion were highly correlated (Table 15). (NUSCO 1987). However, this was rectified in 1984 During 1993, the abundance of all developmental when a net with smaller mesh (202 pm) was used stages at all stations was consistently among the during the early portion of the larval season. Abun- lowest recorded in the 11 year period. Similar annual dance of Stage 1 larvae at the two Niantic Bay stations abundance of Stage 3 larvae at EN and NB suggested was low in comparison to the river, indicating that that the different sampling techniques at the two little,if any, spawning occurred in the bay. Abundan- stadons were comparable, at least for Stage 3 !arvae ces at station NB were consistently greater than at EN, (Fig.15). Generally, Stage 4 larvae were slightly less possibly because NB was located closer to the river abundant at NB than at EN, suggesting that this mouth, the likely source of S tage I larvae, or because developmental stage was somewhat more susceptible - undersampling occurred at EN as a result of extrusion to entrainment than to capture by the bongo sampler. through the 333 m mesh net used there. At station Annual abundance of newly hatched winter flounder NB, ranks of annual abundance indices were similar to larvae should be related to adult reproductive capacity those of the river stations and this suggested that most (egg production) and the fraction of eggs that hatch. Stage I larvae collected in the bay probably originated To examine this relationship, the annual egg produc-from the Niantic River. There was a significant (p 5 tion estimates (Table 13) were compared to the armual 0.05) positive correlation among Stage 1 annual abundance of Stage I larvae. The index of Stage 1 abundances at all stations, except for stations EN and larval abundance was the cx parameter from the NB (Table 15). Gompertz function (Eq. 2) for the Niantic River Stage 2 abundance in 1993 at the three river stations (stations A, B, and C combined). A functional regres-was also among the lowest in the ll year series. In sion indicated a strong positive relationship (t = general, annual ranks of Stage 2 abundance at the three 0.795; p.= 0.006) between egg production and Stage 1 river stations were similar to those of Stage 1. This abundance (Fig.16). 'Ihe abundance of newly hatched implied a similar annual rate of larval loss (mortality larvae was directly related to the adult reproductive and flushing) during larval development from Stage I capacity under the assumption that egg hatchability to 2. Annual abundances at stations B and C were was similar among years. The consistency of this almost identical. Stage 2 larvae occurred predominant- relationship implied that precision in the sampling of ly in the river, but were more prevalent in the bay Stage I larvae and, additionally, that egg production - compared to Stage 1. As with Stage 1, Stage 2 abun- estimates were a reasonable index of annual reproduc-dance at station NB was greater than at EN, which tive capxity, suggested that either station NB was closer to the The dates of peak abundance, estimated from the source of newly hatched larvae or smaller Stage 2 inflection point p of the Gompertz function (Eq. 2), larvae were extruded through the 333-pm mesh net were used to compare the times of occurrence in the used at EN. There was a significant (p s 0.05) posi-tive correlation among all river stations and between stations EN and NB (Table 15). Stages 3 and 4 larvae were generally most abundant C 20- t s 0.795
; p.0.006
/
at station C and their abundance at the two bay sta, y15- 8,8f
/
tions (EN and NB) increased to levels similar to or z sp greater than at stations A and B. In 1993, Stage 3 $go_ larval abundance was the lowest recorded at stations B, 5 C, EN, and NB and low abundance was also evident I 8 90 5- 92 ** for Stage 4 larvae. In previous years,later developmen- 0 tal stages of winter flounder larvae were not found to be homogeneously distributed throughout the river, ju) 0 9,3 93, [ 84
*87 but due to low abundance in 1993 this was not as 5 to 15 20 25 30 8
evident The larval abundance decline at the upper EGG PRODUCTION (X 10 ) river stations (A and B) as development progressed may have represented a gradual flushing to the lower Fig. 16. The relationship (functional regression) be-portion of the river and into the bay. Stage 3 annual tween annual Stage 1 abundance in the Niantic River abundances were similar at the two bay stations and 81 Imm e a Parameter of h Gompem kno tion) and egg production from 1984 through 1993. 176 Monitoring Studies,1993
TABLE 15. Metrh of Spearman's rank. order cornlations among nadons for the annual cumuladve abundance of each devekynental stage of larval winter flounder from 1983 through 1993. Stage Statian B C EN NB 1 A 0.9636 0.9273 0.7654 0.7636 0.0001 " 0.0001 " 0.0060 " 0,0062 " B 0.9182 0.7791 0.8455 0.0001 " 0.0047 " 0.0010 " C 0.7016 0.7727 0.0161
- 0.0053 "
EN 0.5786 0.0622 NS 2 A 0.8546 0.8273 0.3182 0.3636 0.0008 " 0.0017 " 0.3403 NS 0.2716 NS B 0.9000 0.5364 0.6455 0.0002 " 0.0890 NS 0.0320
- C 0.5455 0.5455 0.0827 NS 0.0827 NS EN ft3182 0.D'121 "
3 A 0.9000 0.5091 0.5091 0.3546 0.0002 " 0.1097 NS 0.1097 NS 0.2847 NS - B 0.7364 0.5455 0.4364 0.0098 " 0.0827 NS 0.1797 NS C 0.4909 0.6909 0.1252 NS 0.0186
- EN 0.7636 0.0062 "
4 A 0.3853 0.3119 0.4771 0.5885 0.2419 NS 0.3504 NS 0.1379 NS 0.0568 NS B 0.7182 0.0546 0.3098 0.0128
- 0.8734 NS 0.3539 NS C 0.0636 0.(f175 0.8525 NS 0.8209 NS EN 0.5239 0.0981 NS
- 7he too stadsuca shown in each concladm mauh element are:
conciation coefficient (r), and probabdity of a larger r (NS not significant (p > 0.05),
- significant at p 5 0.05," significant at p 5 0.01).
i river (station A, B, and C combined) and bay (stations because this larval stage was mrely collected there and, EN and NB combined) for each developmental stage similarly, for Stage 4 in the river during 1993 because (Table 16). Dates of peak abundance for Stage 1 of low abundance. In 1993, the dates of peak abun-larvae could not be estimated for the boy stations dance for the first three developmental stages of larvae WinterFlounder 177
TAllLE 16. Estimated dates of peak abundance oflarval winter flounder for each development stage in the Niantic River and Bay and the number of days ocorresponding to the 95% confidence intervat Year - Stage 1 Stage 2 Stage 3 Stage 4 Nimric River 1983 March 5 (3) March 15 (2) April 18 (1) May 2 (4) 1984 March 7 (5) March 9 (5) April 24 (5) May 19 (10) 1985 March 11 (1) March 16 (2) April 25 0) Mayl6 p) 1986 February 26 (1) March 11 (5) April 20 0) May 12 (10) 1987 March 10 (2) March 17 (3) April 20 (2) May 9 (4) 1988 February 29 (1) March 9 (1) April 7 (4) May 1 (5) 1989 March 8 (6) March 12 (5) April 14 (3) May 11 (9) 1990 February 17 (3) February 18 (5) April 21 (2) May 9 (14) 1991 February 27 (3) March 14 (11) April 13 (5) April 29 0) 1992 March 16 (4) April 6 0) April 16 (2) May 2 (2) 1993 March 9 (2) March 14 (8) April 11 p) -' hiie hv 1983 - April 7 (2) April 23 (1) May 10 (4) 1984 - April 8 (2) May 4 0) May 25 (8) 1985 - April ! (4) April 29 (6) May 18 0) 1986 - April 5 (30 April 28 0) May iI (2) 1987 - April 6 (6) April 28 (2) May 16 (4) 1988 March 24 (3) April 22 (2) May 9 (5) 1989 April 13 (1) April 23 (2) May 17 (3) 1990 - April 3 (8) April 23 (2) May 7 (5) 1991 - March 28 (5) April 11 (3) April 29 (4) 1992 - April 15 (4) April 30 (2) - May 7 (4) 1993 - April 3 (44) May 6 (8) May 23 (1I)
- Due to low abundance during the 1993 sampting, the Gompertz function could not be fined to the data.
in the river were within the range of those from the Development andgrowth previous 10-year period. This was also evident for Stage 2 larvac in the bay. Stage I larvae in the river The length-frequency distribution of each larval generally peaked in late February to early March.- stage has remained fairly consistent since developmen-Based on water temperatures of 2 to 3'C during Febru. tal stage determination began in 1983 (NUSCO 1987, , ary and egg incubation times reported by Buckley 1988a, 1989, 1990, 1991 b, 1992a, 1993). Stage-(1982), peak spawning generally occurred in early to specific length frequency distributions by 0.5-mm mid-February. Buckley et al. (1990) reported that egg size-classes in 1993 showed a separation in predomi-incubation time was inversely related to water tempera- nant size-classes for each developmental stage (Fig. ture during oocyte maturation and egg incubation. 17). Stage 1 larvae were primarily (96%) in the 2.5 But a comparison between the 1983 93 February water to 3.5-mm size-classes,87% of Stage 2 were 3.0 to ~j temperatures (Table 6) and the annual dates of Stage 1 4.0 mm,85% of Stage 3 were 4.5 to 8.0 mm, and ; peak abundance in the river did not show a significant 79% of Stage 4 were 7.5 ta 8.5 mm. Larger Stage 3 relationship (Spearman's rank-order correlation coeffi-
.l larvae apparently overlapped smaller Stage 4 fish in j cient p = -0.478; p = 0.137). - The dates of peak total length. These consistent results from year to l
~
abundance for Stage 3 and 4 larvae in the bay were the - year indicated that developmental stage and length of. latest of the 11 year period and they had the largest lan'al winter flounder were closely related. These data 95% confidenceintervals, agreed with laboratory studies on lanal winter floun-der, which showed that there were positive correlations , i 178 Monitoring Studies,1993 l l
50- STAGE 1 between growth and developmental rates (Chambers and Leggett 19871 Chambers et al.1988). This
'O' w relationship was the basis for the estimation of devel- @ 30, opmental stage from length-frequency data.
E The length-frequency distributions of larvac (all stages combined) collected in the Niantic River (sta-h20- tions A, B, and C combined) were quite different from g to- those obtained for Niantic Bay (stations EN and NB g combined)in 1993 (Fig.18). Differences in size-class 0 --
. i i i i i i i i i i i i i i i distribution between the two areas were consistent 20 30 4.0 50 6.0 7.0 80 9.0 with previous findings (NUSCO l987,1988a,1989, 1990,1991b,1992a,1993) and the pattern seen in 50- STAGE 2 spatial distribution by developmental stage, where Stage 1 and 2 larvae were more abundant in the river dU-w than in the bay (see Figs.14 and 15). Smaller S 30, size-classes predominated in the river, which had about $ 82% of the larvae in the 3.5 mm and smaller U 20 size-classes. By contrast, more than 76% of the lan'ae
- h. 10-in the bay during 1993 were in the 4.0-mm and larger size-classes. A slight increase in frequency oflarger g size-classes has been apparent in some previous years 0-"i
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0 0 "
$ " 5-Q 10-2.8 '3.8 '4.0' '5 0' '6 d '7 d '8.0' '9 0' 2.8 3.d '4.8 '5.8 '6.0' '7.d '8.d 9 8 '
LENGTH (mrn) L.ENGTH (mm) Fig.17. Length-frequency distribution of larval winter flounder by developmental stage for all stations com- Fig.18. Length frequency distribution of larval winter bined in the Niantic River and Bay during 1993. (Note fl under in the Niantic River and Bay during 1993. (Note that the vertical scales differ among the graphs), that the vertical scales differ between the graphs). WinterFlounder 179
1992a.1993), suggesting that some older larvae were to estimate larval winter flounder growth rates for imported to the river. This import of larger size. Niantic Bay. Weekly mean lengths during a season classes was apparent in the length-frequency distribu. formed a sigmoid-shaped curve (NUSCO 1988a). The Lion at the river mouth (station RM) in samples linear portion of the sigmoid curve usually occurred collected near maximum flood current during 1991-93 during the middle of the larval season and growth rates - (Fig.19). were estimated by fitting a linear model to individual larval length measurements during that period. This mod :1 adequately described growth and all slopes (growth rate as mm day *3) were significantly (p 5-15- STATION RM 0.001) different from zero (Table 17). In addition. most intercepts of the linear regression were alnur ?, 12-w the approximate size of winter flounder larvae at yg ' hatching. Annual growth rates for station EN were g - variable and ranged from OD48 to 0.100 mm day-1, g6 with 1993 having the lowest value. To validate this estimation technique, growth rates were estimated gs . , _
~
3- from length data collected at station NB from 1979 p through 1989 (NUSCO 1990); annual growth rates o n, , , , , , , , , , , , , , , were highly correlated (r = 0.89; p 5 0.001) with 2h 3.0 4.0 5.0 6.0 7.0 8.0 9.0 those from station EN. LENGTH (mm) In laboratory studies, water temperature affected the Fig.19 Length-frequency distribution of larval winter growth rate of winter flounder larvae (Laurence 1975; flounder collected at the Nianitic River mouth near maxi- NUSCO 1988a). To examine the effect of tempera. 1 mum flood current during 1991 93. ture on estimated annual growth rates, mean water temperatures for Niantic Bay, determined using data Length-frequency data from entrainment collections collected from continuous recorders in the intakes of taken from 1976 through 1993 (station EN) were used Units 1 and 2, were calculated for a 40-day period TABLE 17. Annuallarval wir er flounder growth rates in Niantic Bay as estimated frorn a linear regression fined to length data collected a.t station EN. The 95% confidence intervals and mean water temperatures duririg the first 40 days of the time period are also given. Tirne period Growth rate 95% confidence Mean water Year included * (mm. day 1) interval temperature (*Cf 1976 March 21. May 2 0.100 0.098 0.102 - 7.0 1977 April 3 June 5 0.076 0.073 0.079 6.7 1978 March 26. June 11 0.055 0.052 0.056 4.8 1979 March 25 June 10 0.05 8 0.056 0.0G) 5.9 1980 March 23 - June 8 0.060 0.058 0.062 5.9 1981 April 5. May 31 0.064 0.061 0.067 7.3 1982 March 28.May 30 0.063 0.sou.0.066 5.8 1983 March 6. May 22 0.056 0.054 0.058 5.2 1984 March 25. May 13 0.069 0.066 0.072 64 1985 March 17 - June 2 0.059 0.057 0.061 6.0 1986 March 30. May 11 0.094 0.087 0.101 7.6 1987 March 22. Msy 17 0.079 0.075 0.083 7.0 1988 March 27 May 8 0.088 0.083 0.093 7.1 1989 March 26. May 7 0.069 0.060 0.078 7.0 1990 March 4 May 13 0.071 0.066 0.076 5.3 1991 March 10 April 21 0.059 0.048 0.070 4.7 1992 Marci.15 May 3 0.064 0.059 0.069 5.5 1993 February 28 - May 16 0.048 0.040 0.056 3.3
- Time period of the weekly mean lengths used to estimate growth rate.
- Mean donna a 404ay period starung at the trginning of the week that the first weekly mean length was used in estimating grom1h rate.
180 Monitoring Studies,1993
starting at the beginning of the week when the first 78 o.10 ,, larvallength measurements were used to estimate the r,,, ,0y,2 ,, annual growth rate (Table 17). A positive exponential . relationship was found between growth rate and water _ o.og _ 77 s,7 temperature (Fig. 20). A similar exponential relation. g o,o ship of temperature to Isrval growth was reported for g o2 g A plaice by llovenkamp and White (1991). If tempera- 8'
- 0.06 - . s2 g.'es si ture affects growth rate, then the length of a larva at a specific time during the season should be related to
,3 44 so water temperatures to which it has been exposed. 034 , , , , ,
Therefore, the mean length of larvae collected at 3 4 5 6 7 a station EN during the period of April 1 15 for each MEAN WATER TEMPERATURE ('C) . year was compared to the mean March water tempera-tures (Fig. 21). Again, there was a positive relation. Fig. 20. The exponential relationship between mean ship with larger mean lengths associated with warmer water temperature T (*C) and the estimated growth rate O March temperatures. As concluded previously from (mm per day) of winter flounder larvae at station EN from comparisons of annuallength-frequency distribution 1976 through 1993 (0 = 0.029 e"), and developmental stages, growth and larval develop-ment were found to be closely related. If water temper-ature affects growth rates, then it should also affect 5 oi. q ,, _om larval developmental time. The timing of peak larval --. : p . o.oot a3. ,73 abundance should therefore be related to the rates of recruitment and loss (including mortality andjuvenile ki je 4j so . 64 oo , es
, ,3 metamorphosis), which, in turn, would be affected by g g so
,, ,7 larval development. Annual dates of peak abundance d 3.5 2 .
- 92 as of larval winter flounder collected at EN were negative- z a2 79 i 7a ly correlated to the mean water temperature in March and April (Fig.22). Earlier dates of peak abundance h3/ -
U esi were associated with warmer mean water temperatures. 2.5 ,,,,,,,,,,,,,,,,,,,,,,,,, This agreed with the results of Laurence (1975), who 1 2 3 4 5 6 found that winter flounder larvae metamorphosed 31 MARCH TEMPERATURE (C) days earlier at 8'C than at 5'C. Annual dates of peak Fig. 21. The relationship between annual mean March abundance varied by 41 days during the 17. year period, water temperature (*C) and the mean length during April possibly because of a 3.6*C difference in the March- 1-15 at station EN for 1976 through 1993. April water temperature between the earliest (April 13, 1991) and the latest (May 23,1978) dates of peak 8 . abundance. Despite the wide range in annual growth $ MAY 20 - 7e n rates, a consistent relationship was found between 9 7e 8 length frequency distribution and stage of development 8 g3,1 l MAY 10 - (Fig.17). This was consistent with laboratory obser- r a2 84
' , 02 vations for larval winter flounder as Chambers et al. h APR 30 - .,. .,
(1988) found that, at metamorphosis, age was more g APR 20 - ., se . "s? variable than length and larval age and length were w ,2, m g 83 , independent. 4 P
- 0 001 as 7s et Growth rates were also estimated for Niantic River APR 10 , , , ,
8 larvae using length data from station C with the MARCH APRILWATERTEMPERATURE methods given above. Station C was selected for this analysis because all developmental stages were col-Fig. 22. The relationship between March-April mean lected there in abundance (Fig.14). Estimated growth water temperature (*C) and the annual date of peak abun. 1 rates for larvae from the river were generally greater dance (estimated from the Compertz function) of winter 4 than for larvae from the t iv and the rate for 1993 for flounder larvae at station EN from 1976 through 1993. l WinterFlounder 181 j l l
l. the river was the lowest during the ll-year period significant (p = 0.035; r2 = 0.567), with the coeffi-(Table 18). Again, a linear model provided a good fit cient for temperature positive and the one for Stage 2 and slopes (growth rates as mm day'3) were highly abundance negative, although the Stage 2 coefficient significantly (p $; 0.001) different from zero. . Growth was not significant (p = 0.055). These results sugges- ; of larvae in the river was similar to laboratory growth led that winter flounder larval growth in the Niantic rates of 0.104 and 0.101 mm day'1 at mean water River may be a function of both water temperature and temperatures of 6.9 and 7.5'C, respectively (NUSCO larval density. A laboratory growth study of larval 1988a). An annual mean water temperature was deter. winter flounder held at 8'C showed a decrease in mined from surface and bottom temperatures measured growth rate as prey densities decreased (Laurence at the time of sample collection during a 6-week 1977). "Ihis study, along with the apparent density-period starting the same week from which the first depe' dent growth in the Niantic River, suggested that length measurements were used in the growth rate as LP.e number of feeding larvae increased, the numbers . calculation. Previously, there was no apparent relation- of available prey declined to levels less than optimum ship between growth rates in the river and water - far larval growth. temperature, but a negative relationship was found Slight declines in growth rate caused by less than between growth and the abundance of Stage 2 larvae, optimal food, unfavorable temperatures, disease, or suggesting density-dependent growth (NUSCO 1990, pollution leads to longer developmental times, during 1991b,1992a,1993). The abundance of Stage 2 which high rates of rnortality have a profound effect larvae was examined because it is during this develop- on recruitment (Houde 1987). Food availability and mental stage that larvae begin to feed. With the water temperature appeared to be the two most impor-addition of 1993 data this density-dependent growth tant factors controlling larval growth (Buckley 1982). relationship was no longer significant (p = 0.322) Although Laurence (1975) demonstrated that the when tested with a functional regression. Because metabolic demands of larval winter flounder increased there was a strong relationship between growth and at higher temperatures, the growth rate also increased water temperature in the bay, both Stage 2 abundance if sufficient food resources were available, and other (a parameter; Eq. 2) and water temperature were used laboratory studies (Laurence 1977; Buckley 1980) as independent variables in a multiple regression showed that larval winter flounder growth rates depend model to examine growth rates. Prior to conducting upon prey availability, In summary, growth and ' multiple regression analysis it was determined that the development oflarvae in Niantic Bay correlated with two independent variables were not correlated water temperature, but in the Niantic River growth (Spearman's rank-order correlation coefficient p = appeared to be an interaction of water temperature and 0.145; p = 0.670). The multiple regression was density-dependency. TADLE 18. Annual tarval winter flounder growth rates in the Niantic River as estimated from a linear regression fit to length d sta couected at station C. The 95% confidence intervals and mean wster temperatures during the first 6 weeks of the time period are also given. Ttme period - Growth rate 95% confidence Mean water Year included * (mm-day4 ) interval temperature (*C)* - 1983 March 20 - May 1 0.100 0.096- 0.104 6.1 1984 March 25 May 6 0.100 0.094 0.105 6.4 1985 March 31 May 26 0.084 0.080- 0.088 7.7 , 1986 March 23 May 4 0.109 0.103- 0.115 8.0 1987 mrch 22 May 10 0.099 0.095 0.103 7.2 1988 Wrch 20 - May 21 0.099 0.094 - 0.104 6.8 1989 March 26 Wy 21 0.087 0.082 - 0.092 7.4 1990 March 25 Wy 13 0.106 0.099 0.113 7.5 1991 March 10 Apr0 28 0.123 0.114 - 0.132 69 1992 March 15 - Wy 17 0.088 0.083 0.093 5.7 1993 March 7 Msy 16 0.070 0.065 - 0.075 4.1 I
- Time period of the weekly mean lengths used to estirnate growth rate. j b
Mean during a 6. week period starung the week of the fint weekly mean length used in estimating growth rate. ' 182 Monitoring Studies,1993
Mortality contact predators, including carnivorous copepods and amphipods, enidarians, and ctenophores. Based on length-frequency distributions in the river There are numerous accounts of jellyfish preying during 1993 (Fig.18) and previous years, most winter upon and affecting the abundance of fish larvae. I ounder larval monality occurred between the 3.0- to Several species of hydromedusae and the 4.0 mm size-classes. About a 90% decline in frequen. scyphomedusan Aureliaaurita prey upon Atlantic cy occurred in 1993 between these two size-classes, herring larvae (Arai and Hay 1982; Moller 1984), and which included yolk-sac (Stage 1) and first-feeding laboratory studies with Atlantic cod (Gadus morhua), Stage 2 larvae. This initial large decline was followed plaice, and Atlantic herring have shown that the I by smaller decreases to the 5.0-mm size-class, indicat- capture success by A. aurita increased with medusa! ! ing a reduction in the mortality rate. Pearcy (1962) size (Bailey and Batty 1984). Evidence of a causal reponed a greater mortality for young winter flounder predator-prey relationship on larvae of plaice and larvae (20.7% day'3) compared to older individuals European flounder (Platichthysflesus) by A. aurita (9.14 day'3). In a laboratory study on winter flounder and the ctenophore Fleurobrachiapileus was reponed larvae, Chambers et al. (1988) reported that larval by van der Veer (1985). However, predation by these mortality was concentrated during the first 2 weeks species was believed to only terminate the plaice after hatching. Based on the estimated growth rate in larval season and did not ultimately affect year-class the river for 1983 of 0.077 mm day'3 (Table 18),it strength (van der Veer 1985; van der Veer et al.1990). would require about 13 days to grow from 3 to 4 mm. Pearcy (1962) stated that Sarsia tubulosa medusae The above 90% decline between these size-classes were important predators of larval winter flounder in would be equivalent to a mortality of about the Mystic River, CT, and had greatest impact on 16% day ~I, similar to that reported by Fearcy for younger,less mobile larvae. Crawford and Carey young winter flounder larvae in the Mystic River. (1985) reported large numbers of the moon jelly (A. Laurence (1977) found that winter flounder larvae had aurata) in Point Judith Pond, RI and believed that they a low energy conversion efficiency at first feeding werc a significant predator of larval winter flounder. (i.e., Stage 2) compared to later developmental stages, A possible predator of winter flounder larvae in the and that it was probably a " critical period
- in larval Niantic River was medusae of the lion's mane jelly-development Hjorleifsson (1989) showed that the fish (Cyanea sp.), which was prevalent in the upper i ratio between RNA and DNA, an index of condition ponion of the river at station A. Marshall and Hicks 1 and growth rate, was lowest at the time of first feeding (1962) also reported that jellyfish were abundant in the of winter flounder (about 4 mm) and that these ratios upper river. A laboratory study showed that winter were affected by food availability. The " critical peri- flounder larvae contacting the tentacles of the lion's od" concept, hypothesized by Hjon (1926), was dis- manejellyfish were stunned and ultimately died, even cussed by May (1974) for marine fishes. In many if not consumed by the medusa (NUSCO 1988a).
cases, the strength of a year-class is thought to be During 5 of the 11 years (1983,1984,1986,1989, determined by the availability of sufficient food after and 1990) that larvae were sampled at station A, completion of yolk absorption. weekly mean larval abundance was negatively correla-Predation is likely an important cause of larval ted (p 5 0.05: Spearman's rank-order correlation winter flounder monality. The escape response of coef5cient p range of -0.736 to -0.927) to weekly ) larval winter flounder to predators was studied by mean jellyfish volume during the period when Williams and Brown (1992). They found that escape medusae were collected. In 1993, jellyfish abundance response increased with increasing larval size, but was bimodal with a smaller peak in mid-March and remained slower than that of other larval fishes exam- the larger in late April (Fig. 23). During the time of ined. Larval winter flounder may be vulnerable to both peaks, jellyfish abundance was greater than the both fish and invenebrate predators. Larval winter previous 10-year average. Although the 1993 annual flounder were found to be vulnerable to attacks by larval abundance was among the lowot at station A - planktivorous fishes. However, the occurrence and (Fig.13) and coincident with higher than average abundance of fishes that could potentially prey on jellyfish abundance, larval abundance was also low at larval winter flounder is low, panicularly du ing the the remaining river stations where jellyfish were rarely early portion of the larval winter flounder season. collected. Therefore, the low abundance of larvae in Most predation probably is likely from invenebrate the river could not be directly attributed to jellyfish WinterFlounder 183
I 30 - g 5- r . -0.579
-- 1983-1992 92 p-oms "E75- *,so ;
{ g - 1993 g4 n, g 2o- I g msg . ! 15- 3-
'.' as .
g y
'7 eA 8.' e2 i
s to- g 3 , , 5 2 i i i i i e i i i [#' 10 15 20 25 30 35 40 45 50 5- 5 "b~I' Jf 8 EGG PRODUCTION (X 10 ) o g2. e anonsh ( nct onal r ss n c. 17 24 310172431 7 14 21 28 5 FEB MARCH APRIL MAY Niantic River and the larval recruitment index (logarithm f the ratio of the annual abundance of 7 mm and larger Fig. 23. Comparison of Cyanea sp. weekly rnean vol-anae t the egg prodution) at nation M from N umes collected in 1983-92 (with 95% confidence inter- thr ush 1993, vals) to weekly volumes in 1993. Collections we>e made at station A in the Niantic River, the winter flounder larval period. Because there was increasing evidence that many of the winter flounder predation in the upper portion of the river. Although larvae coliccted at station EN did not originate from during some years there appeared to be a relationship the Niantic River, this compensatory relationship between the temporal decline of winter flounder larval suggested that annual egg production estimates for the abundance at station A in the Niantic River with the Niantic River were consistent with regional trends in occurrence of lion's mane jellyfish medusae, for other winter flounder egg production. years there was no relationship between annual larval Because the egg production estimate was used in abundance at station A and annual mean jellyfish calculating the larval recruitment index above, a volume. The decline in larval abundance at station A Possibility existed of introducing correlation between may also be attributed to a gradual flushing of larvae the independent (egg production) and dependent (recruit-out of the upper portion of the river, ment index) variables. Derefore, another approach for The possibility of density-dependent mortality of winter flounder larvae was examined using a function detecting the presence of density-dependent larval mortality for the Niantic River stock was used, wherc ! (Eq. 4) provided by Ricker (1975) that requires esti, annual larval mortality rates from the river were mates of annual spawning stock size and larval recruit, ment. The annual egg production estimate in the compared to estimates of river spawning stock size (i.e., egg production). Total larval mortality in the Niantic River (Table 13) was used as a rneasure of river for 1984 93 ranged from 82.4 to 97.9%, with a spawning stock size. De a parameter from the Gom. pertz function fit to the abundance of 7-mm and larger mean instantaneous rate Z of 2.77 (Table 19). To determine if density-dependent mortality could be ident-larvac collected from 1976 through 1993 at station EN ified in the larval stage, the values of Z were compared was selected as a measure of larval recruitment. to egg Production estimates using functional regres-Larvae in the 7 mm and larger size-classes were used because they would soon metamorphose into juve. sion. Previously, a significant (p s 0.05) relationship niles. A larval recruitment index was calculated by was apparent,- such that when egg production taking the logarithm of the ratio of the a parameter increased, larval mortality also increased (NUSCO for 7-mm and larger larvae to the egg production 1991b). But with the addition of 199193 data, this estimates. His value was plotted against egg produc- relationship was no longer significant (p = 0.204), The mortality rate for 1991 was lower and the mies for tion estimates and the slope determined with function-al regression (Fig. 24). Although there was some 1992 and 1993 were higher than expected, based on - scatter around the relationship, a significant (t = total egg production estimates (Fig. 25). Therefore. it
--0.579; p = 0.015) negative relationship was found, was no longer evident that density-dependent larval indicating that compensatory mortality occurred during mortality was occurring in the Niantic River.
184 Monitoring Studies,1993
4- , , o.4 3g , TABLE 19. Estimated larval winter flounder total mortality from p - c204 89 . ha&g to 1.% h sMst E 8.s u g 3- , M ance M x g 93 g ,7 Newly 7-mm Mortatity Instantaneou
,. + Year hatched size-class (%) mortality rate 92 .
84 cr 2- 8) 1984 6.500 654 89.9 2.30
. 1985 13.773 452 96.7 3.42 86 h 1986 2,483 438 82.4 1.73 1987 6,480 474 92.7 2.62 1 24,561
, , , , 1988 678 97.2 3.59 5 10 15 20 25 39g9 39,392 394 97,9 3 gg 8 7,915 EGG PRODUCTION (X 10 ) 1990 653 91.7 2.49 1991 3.992 5&) 86.5 2.00 Fig. 25. Lack of relationship between annual winter 1992 8.02o 609 92.4 2.58 flounder egg production and instantaneous larval mortali. 1993 1.874 88 95.3 3.06 ty rate in the Niantic River from 1984 through 1993.
Juvenile winter flounder the result of additional fish entering shallow water once water temperatures began to decrease from late Age-0 juveniles (summer) summer peaks. Saucerman and Deegan (1991) also found that young winter flounder responded to warm Abundance. Although beam trawls are much water temperatures during late August in Waquoit more efficient than small otter trawls for collecting Bay, MA by moving into deeper water and returning juvenile flatfish (Kuipers et al.1992), the densities to the shallows after those areas became cooler. reponed below should be regarded as minimum esti- Catches during th . previous two sampling dates in mates because of inefficiencies in the collecdon pro- September may also have been negatively affected at - cess. For example, using a beam trawl Berghahn LR by large mats of the alga Enteromorpha clathrata, (1986) caught more young plaice at night in compari- which likely reduced sampling efficiency of the 1-m son to samples taken during the day and Rogers and beam trawl, and by a boat moored at WA, which lockwood (1989) showed that replacing tickler chains caused a deviation in the normal tow path to some-norTnally used with even heavier, spiked chains nearly what sha!!ower or deeper water. Bagge and Nielsen doubled catches. The efficiency of the NUSCO l-m (1988) noted reductions in age-O plaice abundance in beam trawl was discussed in NUSCO (1990). In late Demark when filamentous algae covered large parts June of 1983, two tickler chains added to the beam of their shallow nursery area. Pihl and van der Veer trawl considerably increased catch efficiency as older (1992) also reported similar density reductions of and larger fish apparently were able to avoid the net young plaice in a Swedish bay when about half of the without them in place (NUSCO 1987). bottom became covered by Enteromorphaflexuosa and Compared to previous years of sampling, the initial the organic content of the sediments nearly doubled. , numbers of tiewly metamorphosed young-of the-year 'Ihe median CPUE for the first half of the season at winter flounder were relatively low at all stations in station BP was 22.5, the lowest since 1989, and the 1993, particularly in the Niantic River, where abun. CPUE at RM was 8.3, which was the smallest of the dance was only 10-20 fish 100m-2 (Fig. 26). Al- 5 year time series (Table 20). Early season densities - though densities in the bay were greater than in the in the Niantic River were also historic lows (10.6 for river, considerably fewer fish were present than in LR and 5.0 for WAl Table 21). Densities for the 1991 or 1992. As in most other years of sampling, second half of the summer at LR (5.0) and WA (5.5) numbers of young declined quickly at the bay stations were less than or equal to the lowest values found and none were collected by late summer. Similar to during 11 years of sampling in the river. A plot of - observations made in several other years, a small moving average densities for each station illustrated increase in abundance occurred at the river stations the rapid decline of young at the bay stations during ' during the hst day of sampling in September,perhaps all years of sampling, regardless of initial numbers WinterFlounder 185
i ug 30- LR 1993 a E M-23 8 8
~
x 20 x 20- ' W %~ W-5 5 E10- E10- 1 1 2 0s 20. ' MAYJUNE JULY AUGUST SEPTEMBER MAYJUNE JULY AUGUST SEPTEMBER "E l BP - 1993 "E ' RM - 1993 h h1204 e 250i e
$2004 j h 90i N 1504 h 60- ' $1004 $
k504 -
$0 .-W $ O' N-MAYJUNE JULY AUGUST SEPTEMBER MAYJUNE JULY AUGUST SEPTEMBER Fig. 26. Weekly mean CPUE (12 standard enors) of age.0 winter flounder taken in the Niantic River and Bay during 1993.
(Note that the vertical scales differ among the graphs). present (Fig. 27). During many years, a slight in. MNPS was less variable than abundance as the weekly crease in density usually occurred following the first means had relatively small confidence intervals, al-one or two weeks of sampling in the Niantic River though variability increased as sample sizes became (Figs. 28 and 29). As summer progressed, this was smaller. Mean length of young at LR during late followed by much smaller decreases. The average summer (July through September) was 61 mm in-abundance of the 1993 year-class was somewhat less 1993, which was exceeded only by the mean of 66 than that of the 1989 year-class, which previously had mm for 1983 (Table 22). The mean of 51 mm for been the lowest of the ll year time series. WA was also among the highest values observed at Growth. Changes of weekly mean lengths were that station. This 10-mm difference in mean length used to express growth of age-0 winter flounder. A between the two river stations was also the largest consistent, relatively rapid increase .in weekly mean difference observed since 1985, when it was 15 mm. lengths was observed in 1993 for fish in the Niantic The relatively large mean lengths in association with River from May through the beginning of July (Fig. Iow abundance this year and others (e.g.,1983,1984, 30), which was typical for other years sampled. The 1989) may have been indicative of density-dependent rate of increase then decreased through the end of growth. Ilowever, this has not been consistent for all sampling in September. Fast growth after settlement years of study, as other environmental fxtors undoubt-followed by a rapid decline in growth rate was also edly influenced the growth of young winter flounder. reported for young winter flounder in New Jersey bays Almost all fish collected in the bay were smaller by Sogard and Able (1992), who reported nearly than those taken in the Niantic River, especially early - imperceptible growth by the time young reached 50 in the season (Fig. 30). Growth of individuals in mm in length. Growth of age-O winter flounder near both areas was likely affected by water tempemture. 186 Monitoring Studies,1993
i TABLE 20. Seasmal 1.m beam trawl median CPUE (number 100m*2) of ageO winter flounder at two stations in Niantic Bay (RM and BP) frorn 1988 through 1993. Median 95% confidence Coefficient Survey Tows used CPUE interval for of year
- Stanon Season b for CPUE estimate nedian CPUE skewness' 1988 RM Early 39 47.5 30.0 - 72.5 3.68 RM Late 36 7.0 6.0 - 8.0 0.20 BP Early 40 713 32.5-107.5 1.17 BP Late 32 1.6 1.0 - 3.0 0.99 1989 RM Early 40 50.8 26.7 75.0 0.64 RM Late 32 0.0 0.01.3 1.79 BP Early 39 20.0 6.3-32.5 1.78 BP Late 12 0.0 0.0 - 0.0 3.46 1990 RM Early 40 40.0 17.5 55.0 0.81 RM Late 24 0.0 0.01.0 2.40 BP Early 40 32.5 12.5 - 50.0 0.89 BP Late 24 1.0 0.02.0 0.89 1991 RM Early 44 46.3 15.0 65.0 0.63 RM Late 0 - - -
BP Early 44 30.0 5.0 107.5 2.29 BP Late 8 0.5 0.01.0 0.00 1992 RM Early 39 15.0 3.0 - 60.0 1.80 RM Late 0 - - - BP Early 38 110.0 3.0 262.5 1.34 BP Late 0 - - - 1993 RM Early 19 8.3 4.0 67.5 1.69 RM Late 12 0.0 0.0 - 1.0 0.80 BP Early 19 22.5 8.8 172.5 1.21 BP Late 12 0.0 0.02.0 1.44
- For age.o fish. the year-class is the same as the survey year.
- Early seasm corresponds to late May through July and late to August through Septemter.
- Zero for symmetdcally distributed data.
Faster growth occurs in warmer waters unless optimal dependent growth of age-0 plaice in Britain. 'Ihey con-tempentures for growth are exceeded (Sogard and Able cluded that increases in length corresponded to maxi-1992). Water temperature was warmer at the river mum growth expected from prevailing water tempera-stations, particularly in spring and early summer when tures and that growth was not density-dependent. growth was most rapid and probably accounted for Similarly, Pihl and van der Veer (1992) determined some of the differences noted.- Bergman et al. (1988) that growth of young plaice in Swedish bays appeared and van der Veer et al. (1990) noted that growth of to be affected by ambient water temperatures and was young plaice in northwestern Europe was not food- not food-timited. However, Berghahn (1987) and limited, but was related to prevailing water tempera- Karaktri et al. (1989) suggested that food limitation tures and the length of the growing season in different and not water temperature could have been responsible nursery areas. Furthermore, fish grew more rapidly on for gmwth differences of plaice observed among differ-the warmer nursery grounds in embayments than did ent years within the German Wadden Sea. fish settling on beaches in the cooler North Sea. Other factors found to affect growth of young winter Bergman et al. (1988) re-examined reports by Steele flounder include physical location and specific habitat and Edwards (1970) and Lockwood (1972) of density- (Sogard 1990; Sogard and Able 1992). Benthic food WinterFlounder 187
. . . . . ~ . . . . . . ~ . - . . , .. . .-
a TABLE 21. Scanonal 1.m beam trawl median CPUE (number.100m.2) of age # winter flounder at two stations in the lower Niande River (LR and WA)fourn 1983 through 1993. Median 95% confidence Coefficient Survey Tows used CPUE interval for of , y ea r* Statian Season 6 for CPUE estimate median CPUE skewness' 1983 1R Early 30 32.7 20.0 50.7 2.29 m Late 27 10.0 '8.0 133 0.49 1984 LR Early 40 18.8 16.7 25.0 0.63 - LR Late 36 63 3.8 - 7.5 0.58 WA Late - 32 113 8.0 - 17.5 0.94 1985 m' . Early 40 13 3 10.0 16.3 0.91 m Late 32 7.0 6.08.0 0.97 WA Early 40 15.0 10.0 20.0 0.81 WA Late 32 9.0 8.0-10.0 0.70 1936 LR Early 39 33.8' 233 40.0 0.33 LR 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 1987 LR Early 40 59.2 533 73.3 -0.12 LR Late 36 17.9 12.5 26.7 0.70 WA Early 40 283 21.7 383 0.27 WA Late 36 10.6 6.0 13.8 0.83 ~ 1988 LR Early 40 613 52.5 72.5 037 LR Late 36 60.0 50.0 70.0 1.17 WA Early 40 40.0 32.5 - 51.7 0.13 WA Late 36 383 333 51.7 0.22 1989 LR Early 40 17.5 11.7 - 21.7 0.09 m Late 36 8.8 7.0 11.3 0.84 WA Early 40 10.0 8.3 13.8 1.16 WA Late 34 5.5 4.0 10.0 0.66 1990 LR Early 40 156.3 137.5 187.5 . 1.05 m Late 36 20.0 15.0 52.5 1.10 WA Early 40 68.8 50.0 95.0 0.62 WA Late 36 13.5 10.0 19.0 1.20 1991 1R Early 44 77.5 51.7 - 90.0 0.96 1R Late 36 21.7 183 -283 0.75 WA Early 44 37.9 30.0 - 433 1.34 WA Late 36 25.8 213 31.7 1.27 1992 1R Early 40 90.0 57.5 122.5 1.16 IR Late 36 28.1 23.8 333 0.51 WA Early 40 74.6 56.7 82.5 135 WA Late 36 30.0 27.5 32.5 0.23 1993 m Early 20 10.6 7.0 15.0 0.68 LR . Late 20 5.0 - 3.07.0 1.15 , WA Early 20 5.0 3.87.5 2.57 WA Late 20 5.5 4.0 10.0 0.77
- i For age 4 fish, the year. class is the isrne as the survey year.
- Early seancm comsponds to late May through July and late to August through September.
- Zero for symmetricaDy distributed data.
l I 188 Monitoring Studies,1993 I i
t-1000 - 92 Station BP 1988 93 3 900i x W 800- '
$ "E W
8 700i N# l-
$ h 600i w
0 5 500; 91
$Q '
N
< 3q 400i s 9 w '
> s 3002 e= -
s O s 2 200i 93
....,,,s...,, .
100; 88 90 ' s x .. 0, ,89 , , %, , , , , , . . ,,,,,,,,,, MAY JUNE JULY AUGUST SEPTEMBER 250- Station RM - 1988 - 93 WN 200-3 E 58e W u. O Ex 150-W - 0 0 y$ f" 92 4 gw15 100- - g . v..-
@ 93 ,,.- ,, .
s 50- i
. 8 i . *. ,
i 89 '90 .. . s 03 , , , , , ,'"' , ' i'*;,*" N - , - MAY JUNE JULY AUGUST -SEPTEMBER Fig. 27. Moving average of weekly mean CPUE of age-0 winter flounder taken at stations BP and R.M in Niantic Bay from 1988 through 1993. (Note that the vertical scales differ between the graphs). i l WinterFlounder 189 l
Station LR 1983 87 120-100-80-87 60- , l 40-83 84, - j . s - 20- ~. - - m_ . 85 - - . _ w "_ 0 86, MAY JUNE JULY AUGUST SEPTEMBER Station LR 1988 - 93 250 , 200 - 150 -
.s-
..# /
g s 90 ' s 100- e s 92
/ \ . i
.e 50- 91 ,, # .,
~
88 , 89....................,,..'._
.i. _ N _
"..........,...a' 93 . . . , , , , . . .. . . . --- . . . . . . . .- . . . . . . .-~;... . .. ... ... . . , ' " " " " " , , , . .
0 MAY JUNE JULY AUGUST SEPTEMBER Fig. 28. Moving sverage of weekly mean CPUE of age-O winter flounder taken at station LR in the Niantic River from 1983 ' through 1987 and 1988 through 1993. (Note that the vertical scales differ between the graphs). l
.1 190 Monitoring Studies,1993 i
r Station WA- 1985 88 70 - 60-50 - 40-8 7 * """'"... ,*.,. e-s s
~.'.
' i s 30- - <
4 i N.v. . s
.. i s
. 88 .N. i s f,.............a..,, '. ,
i
~
10-85 < . 86 ' 0-. MAY JUNE JULY AUGUST SEPTEMBER Station WA - 1989 93 140-120-100-90 80-92 60-
\
40- ,' '
~ , - ~',
s
,...c.
91-20- B9 '.
****""**"",,.........~.~~.....,'*****..'*.......................,g,....,,
93 ,,-
, * *~ ~..;i;;,g;,,a O-l MAY JUNE JULY AUGUST SEPTEMBER Fig. 29. Moving average of weekly rnean CPUE of age-O winter flounder taken at station WA in the Niantic River from 1985 - 1 through 1988 and 1989 through 1993. (Note that the vertical scales differ between the graphs).
i s
..t WinterFlounder 191 r
g 80 ' production and its availability also likely differed f., 70 4 T among areas in the Niantic River and Bay and from 7 iE LR (solid) , year to year. Karakiri et al. (1989) reported differences
@ 3gj 60 J j,, ~[, ..h -} in the size of young plaice of similar age between
'd v
. J . -I ' Wadden Sea estuarine nursery grounds (larger fish) and f,
j '0i0i coastal waters off Germany (smaller fish). They
- s 3 . suggested that the differences were due to lower water i y 204 M temperature, food limitation, or wave action in the to 104 i WA (dashed) waters outside of the Wadden Sea. Al-Hossaini et al.
E g: (1989) reported greater growth for cohorts of plaice that settled relatively early in Wales, but these fish MAYJUNE JULY AUGUST SEPTEMBER also had higher mortality. Conversely, growth was I slower for late settling cohorts, but survival was higher.
- 80 Mortality. Catch curves constructed from weekly l abundance data by year and station were used to obtain E "7oj i
- estimates of monthly instantaneous mortality rate E RM (solid) (Zmo); this method assumed that young comprised a y 50j J. T single-age cohort throughout the season. With some z 40 : 4 exceptions, the catch curves generally fit the data well h304 with relatively high r2 values (Table 23). No esti-
>- : . . mates could be determined for LR and WA during the
$o yt
, d BP (dashed) high abundance year of 1988 as slopes of these catch curves were not significantly different from zero and -
0 i , , , , , , , , , for WA in 1986 and 1993 because of considerable ; MAYJUNE JULY AUGUST SEPTEMBER variation in weekly abundance during those years. The Zmo estimate for station LR in 1993 was 0.377 (equivalent to a survival of 68.6%) and, except for Fig. 30. Weekly mean length (12 standard errors) of 1988, was the lowest observed since 1983. Long. age-O winter flounder taken in Niantic River utd Bay term averages of Zmo.at LR and WA were 0.634 and during 1993. 0.553, respectively. Mortalny estimates for Niantic TABG 22. Comparison of the mean lengths of age-o winter flounder taken at stadons IR and WA in the Niantic River during late July thmugh Sepemter of 190 through 1993. Mean length
- in mm for statico and year-66 61 59 99 97 % $5 51 51 51 50 48 47 46 45 44 43 43 42 42 42 1R LR 1R 1R tR IR WA WA IR WA WA 1R WA IR 1R WA 1R WA WA WA WA 83 93 84 89 85 91 91 93 88 88 89 92 37 86 87 92 90 84 85 90 86 Difference between the late seasonal mean at LR as compared to that for WA:
i Year 84 85 86 87 88 89 90 91 92 93 Difference in mm 16 15 4 2 0 8 1 1 4 10-
- Means underlined ue not sigrtificantly (p 5 0.05) dJferent from each other as determined by analysis of variance and Duncan's multiple-range test.
c. 192 Monitoring Studies,1993
- .. . -~ . .
- TABLE 23. Monthly instantaneous total mortality rate (Z) estirnates as determined from catch curves for ege4 winter flounder taken at two stations in the Niantic River (M and WA) from 1983 through 1993 and two stations in Niantic Bay (RM and BP) from 1988 through 1993.
Ninntic River $2ntie Bay Standard Standard Year Station n' alope' error r2 Station n* slope 6 error r2 1984 LR 16 -0.129 " 0.017 0.80 BP . . . - 1985 15 -0.118 " 0.015 0.82 . . . . 1986 15 -0.127 " 0.012 0.89 . . . - 1987 15 0.108 " 0.021 0.67 - . . . 1988 19 NS . - 16 0.405 " 0.031 0.92 ' 1989 12 -0.154 " 0.022 0.84 11 -0.485 " 0.044 0.93 1990 13 -0.322 " 0.028 0.92 15 -0.412 " 0.035 0.92 1991 18- -0.140 " 0.016 0.82 12 0.667 " 0.069 0.90 1992 18 -0.129 " 0.019 0.74 10 -1.046 " 0.103 0.93 1993 9 4 087
- 0.028 0.57 7 0.433 " 0.066 0.90 1985 WA* 16 -0.084 " 0.023 0.51 RM - - . .
1987 16 -0.139 " 0.016 0.84 . - . . 1988 19 NS - - I8 -0.235 " 0.025 0.85 1989 13 -0.145 " 0.028 0.71 15 -0.413 " 0.035 0.91 1990 15 -0.235 " 0.028 0.84 13 -0.523 ** 0.051 0.90 1991 18 -0.049 " 0.011 0.54 10 -0.557 " 0.131 0.69 j 1992 16 -0.112 " 0.009 0.91 9 0.871 " 0.07A 0.95 1993 10 NS - - 8 -0.382 " 0.079 0.80 Mortal:ty (2.) Survival (S ) Mortality (Z.) Survival (S ) 1984 M 0.560 57.1% BP - . I 1985 0.512 59.9 % - - 1986 0.552 57.6 % - - 1987 0.469 62.6 % - . 1988 - - 1.759 17.2 % 1989 0.669 51.2 % 2.106 12.2 % 1990 1.398 24.7 % 1.789 16.7 % 1991 0 608 54.4 % 2.879 5.5% , 1992 0.560 57.1 % 4.543 1.1% 1993 0 177 68 6 % 1 902 14.9 % Mean 0.634 53.1% Mean 2.496 8.2% SD 0.298 SD 1.085 CV 47 % CV 43 % 1985 WA* 0.363 69.9 % RM . . 1987 0.604 54.7 % - - 1988 - . 1.021 36.0% 1989 0.630 $3.3% 1,794 16.6 % 1990 1.021 36.0% ' 2.271 10.3 % 1991 0.213 80.8 % 2.419 8.9% 1992 0.486 61.5 % 3;781 2.3%- 1993 - 1.660 19.0% Mean 0.553 57.5% Mean 2.158 11.6 % SD 0.277 SD - 0.937 CV 50% CV 43 % .
- Weekly sampling during 1984 92 and biweekly sampling in 1993, 6
Probabihty level that the slope of the catdi curve differs from aerois shown: ' L. NS not significant (p > 0.05), * - significant at p 5 0.05," significan at p 5 0.01.
- Although having a significant slope, the catch curve for 1986 at station WA did not provide a reliable estimate of Z tecause of considerable variation in weekly abundance.
WinterFlounder 193
.j
River winter flounder were usually greater than the lengths of fish in the bay approach those at WA. equivalent Z,no value of 0.371 reported by Pearcy However, the last few weekly means at RM were (1%2) for the Mystic River, CT estuary, but were based on small sample sizes as only a few fish were d found in the bay by then. The 95% confidence inter-similar to various estimates (0.563 - 0.693 month ) made for young plaice in British coastal embayments vals for weekly means at each station were relatively (Lockwood 1980; Poxton et al.1982; Poxton and small and did not show changes expected if many - Nasir 1985; Al Hossaini et al.1989). Mortality of smaller fish joined the larger young already present at young was much greater in the bay than in the river. WA. Based on the length and abundance data,'it is The 1993 estimates for Z of 1.902 at BP and 1.660 at likely that few or no fish emigrate from the bay to the RM were also below average (2.496,2.158). How- river during summer, in contrast, based on increases ever, except for RM in 1988, no fish have ever been in density generally noted from late May through early found at the two bay stations by the end of summer. June (Figs. 28 and 29), some recruitment to LR and Even in 1988, densities at RM in late summer were WA may have occurred early in the season from other , only 10-15% of those in the river, nearby areas of the river having similar potential for Because the mortality estimates were based on the growth. disappearance of young at a station,it is possible that If no substantial emigration into the river took some of the decrease could have been due to off-station place, lower densities at the bay stations also could emigration as well as mortality (i.e., fish movements have resulted from movements into other areas of the would have been indistinguishable from natural mortal- bay. However, few young have been taken since 1976 ity). However, Saucerman and Deegan (1991) noted by otter trawl or seine sampling in Niantic Bay or in only limited (< 100 m) movements of marked young other nearby offshore waters until late fall or winter winter flounder from various areas of Waquoit Bay, (see following section), when many young winter MA, particularly during the first few months after flounder withdrew from the river in response to decreas-setdement Also using marked fish, Howell and ing water temperature._ At this time, winter flounder Molnar (1993) reported only one fish that moved as small as 30 mm became available for capture by among three different sampling sites within New otter trawl sampling in LIS, Small juveniles are also Haven Harbor, CT. Riley (1973) noted that young caught from February through early April in the plaice moved very little from their location in shallow Niantic River during the adult population surveys (see water during summer and individuals even retamed to Age-1 juveniles [ late winter), below). If young were previous positions if displaced laterally or to deeper present at deeper stations in the bay during mid-water. As noted above, sizes of age-0 winter flounder summer, they hould have been collected during TMP found in the river and bay differ noticeably, it was sampling. Thus, high natural mortality of young therefore assumed that an influx of many smaller fish - winter flounder in Niantic Bay is likely the reason for from the bay likely would have decreased weekly the decline in density following larval metamorphosis means and increased the variability observed in the and settlement to the bottom and it is likely that few length frequency distributions at the river stations, older juveniles are },roduced in the bay. , unless extraordinarily fast growth of emigrating fish The reasons for high mortality of juvenile winter occurred. His characteristic may be used to determine flounder after settlement have not been investigated. if there was any emigration of young from the bay Predation by caridean shrimp (Crangon spp.) has been into the river during summer, which could have ac- suggested as the cause of high mortality after settling counted for a fraction of the observed loss of fish. for both winter flounder (Witting and Able 1993) and Because weekly mean lengths of young have usually plaice (Lockwood 1980; van der Veer and Bergman been somewhat larger at LR than at WA and at RM 1987 Pihl 1990; van der Veer et al.1990; Pihl and than at BP, lengths of fish at stations WA in the river van der Veer 1992). Van der Veer et al. (1990) specu-and RM in the bay should show the smallest differenc- lated that, in general, predation by crustaceans on es when the two areas are compared. At the start of juvenile flatfishes may be a common regulatory sampling in May, fish in the river were about twice process. Witting and Ab!c (1993) found that the size the size of those in the bay (Fig. 31). His large size of age-0 winter flounder significantly affected their differential was maintained between the two areas probability of predation by sevenspine bay shrimp throughout most of the season, it was not until (Crangon septemspinosa), with greatest risk found for nearly the end of the sampling season at RM that smallest fish. Juveniles apparently outgrew predation 194 Monitoring Studies,1993
- 70 - 1988 60- 1989 60 WA (solid) WA (solid) 50
]
g 50.: gg glh' $ 40J 'I' a b 402; 5 d ," 2
- 7. . - - , .a z 3 30; '
@ 30 i ; . :r ' iD y' s 2
> 20J j F'
> 20-!. y '- -
" j 10~
10J Y y RM (dashed) g 0;, RM (dashed) O',, ,,,, , , , ,,,,,,,,,,, ,,,,,,,,,3, ,, , , ,,,, 0 2 4 6 8 10 12 14 16 18 0 2 4 6 8 10 12 14 16 18 WEEK WEEK - 50, 1990 ._, 70- 1991 45] WA (solid),
- 1 60 WA (solid) T .
5 40j 2 g , v i Q 354 , a 50.: , , @ 30-! ? h 402 2 25 -l TA z : 6 20j 2 !
?
s 30i . > 151 ,- > / i h 10j { 20 :3. / ,c " g 5i RM (dashed) g . RM (dashed) 0'i i . . ..i.i i,,i i .,,,, 0 ; m , , , , , 7. , ,,,n ,,,,,, 0 2 4 6 8 10 12 14 16 18 0 2 4 6 8 to 12 14 16 18 WEEK WEEK
.-. 50, 1992 E :
WA (solid) g . g 35 ;
@ 30]
z 25i . , , 6 s 20-i ' 7"'
>, 15 j: ,, j g 10q g 5j RM (dashed) 0-, , ,,,,,,,, ,,, ,,,, , ,,
0 2 4 6 8 10 12 14 16 18 WEEK Fig. 31. Comparison of weekly mean length and 95% confidence interval of age-0 winter flounder taken at stations WA in the Niantic River and RM in Niantic Bay from 1988 through 1992. (Note differing scales among the graphs), by shrimp when they reached 17 mm in length, which vulnerability of young winter flounder to predation by meant that they have to double in size after settlement shrimp and other organisms, Variation in growth, before attaining a size refuge from shrimp predation. which can depend upon specific location of settling, Therefore, the duration of time spent in a vulnerable specific habitat within a location, or. temperature - size range, which is related to growth rate, affects the (Sogard 1990; Sogard and Able 1992) may have I l WinterFlounder 195
significant implications for young winter flounder were well above avera survival after metamorphosis. Greater mortality in never approached 1 m ge, observed densities t the bay may be related to the smaller size of young and the greater numbers of fish available to prey upon Age-Ojuveniles (latefall and early winter) them in these deeper water areas. This is analogous to reports of higher monality for age-0 plaice in Europe, Young winter flounder disperse from shallow waters where survival in the shallow inland Wadden Sea of near the shoreline to deeper watts as water tempera-The Netherlands was greater than that of plaice inhabit- tures decrease in fall and become available for sam-ing the more open and deeper British bays, which had pling by the otter trawl used in the year-round TMP, more resident fish predators (Bergman et al.1988). Young are first regularly captured by trawl at the two Adult recruitment for many fishes is greatly affected shallower inshore stations (NR and JC) adjacent to by density-dependent processes occurring during the inshore nursery grounds in November, the near-shore first year of life following the larval stage (Bannister Niantic Bay stations (IN and NB) in December, and at et al.1974; Cushing 1974; Sissenwine 1984; Ander- the deeper-water stations in LIS (TT and BR) in Janu-son 1988; Houde 1989; Myers and Cadigan 1993a, ary. A A-mean (NUSCO 1988b) index of relative 1993b). Bannister et al. (1974), Lockwood (1980), abundance was developed for these age-O fish using and van der Veer (1986) all reported density-dependent TMP catch data, beginning with these months and mortality for young plaice, although examination of continuing through the end of February. The Novem. their findings indicated that greatest rates of monality ber-February period was a transitional period follow-occurred only when extremely large year-classes of ing the beam trawl sampling of young in summer and plaice were produced (three to more than five times preceding the catch of this cohort of fish as age-1 larger than average). A similar situation may have juveniles during the intensive adult winter flounder existed in the Niantic River as the peak (> l m-2) surveys that take place in the Niantic River from late densities reached during early summer in 1990 and February through early April. 'Ihe most recent abun-1992 (Figs. 28 and 29) resulted in greater rates of dance index given in this report is for the 1992 year-decline than during other years. Although apparent class; the A-mean for 1992-93 was 31,1 (Table 24). survival rates were highest in 1988, when densities TABtI 24. 7he late fall-carly winter seasonal' A-mean CPtJE6of age-08 winter flounder taken at the six trawl monitoring stations in the vicinity of MNPS from 1976-77 through 1992 93. Survey year' Number of samples Non-zero observations A mean 6 95% confidence interval 1976 77 42 36 ti.1 2.0 103 1977 78 42 38 5.1 2.37.9 1978-79 42 36 4.2 2.044 1979-80 42 38 4.2 2.2 - 6.2 198o-81 42 39 10.1 4.3 - 15.9 I981 82 42 39 7.7 2.9 12.5 1982-83 42 37 19.6 9.0 - 303 1983-84 42 39 6.6 3.2 - 10.0 1984-85 42 35 7.4 1.7 - 13.1 1985-86 42 39 8.t 4.4 - 11.7 1 1986-87 42 39 11.7 3.4 - 19.9 I 1987 88 42 41 4.8 2.1 - 7.5 1988-89 42 41 29.6 11.8 - 473 1989-90 42 42 !!3 6.7 - 15.9 1990 91 42 4o 21.7 6.7 36.8 :' 1991 92 42 41 19.0 7.6 303 1 1992-93 42 39 31.1 7.4 - 54.8 1
- Data seasonaUy restricted to November-February for NR and JC, December-February for IN and NB, and January-February for 17 and BR. A few indices differ from those given in NtlSCO (1993) because the number of samples analyzed per year was standardized at 42.
- Catch per standardized tow of 0.69 km (see Materials and Methods of Fish Ecology secticm).
' For age-O fish,the year-class is the same as the first year given.
"I 1% Monitoring Studies,1993 l
l
l
-l Although having a wide confidence interval associa-ted with it, this value is the largest of the 17 year y go series and is indicative of the strength of the 1992 4 soj year-class. Even though winter flounder abundance 9 yod generally has been decreasing, the A means for the last 5 years were among the largest values recorded-h 60d ,
g504 . Since 1983, when data were first available from the g 4o.; beam trawl sampling, the fall-early winter A-means g 3oj , were compared to 1-m beam trawl densities determined 3 20d .[ I.- ! for late summer at stations LR and WA in the Niantie g inj F /,, L, River (Fig. 32). These abundance indices were signifi- Eo 4 i ,
. .'1 cantly correlated (Spea.rman's rank-order correlation 78 78 80 82 84 86 88 90 92 coefficient p = 0.85; p = 0.004). However, there was YEAR-CLASS no apparent relationship found between the median Eg. 33. Comparison between the late fall-carly winter CPUE of winter flounder smaller than 15 cm taken in the Niantic River during the subsequent (late Febru.
uns nal A.mean CPUE (solid line) of age.0 winter ary-carly April) adult winter flounder survey and TMP f1 under (all trawl m ni ring pr gram stations) and the Niantic River (stations 1 and 2) spawning survey median A means (Fig. 33). For the 1985 and earlier year-CPUE (dashed line) of winter flounder smaller than 15 cm classes, more juvenile winter flounder were taken in
. for the 1976 92 year-classes.
the river than at the six TMP stations (five of which are outside of the Niantic River). But since the 1988 year-class was produced, consistently more fish have in the vicinity of the gear (Parrish 1963). Mean been taken by the TMP.
. lengths of age-O winter flounder taken by otter trawl Relationships among abundance m. dices of j.uvenile in fall were about 15 to 25 mm larger than those winter flounder may have been obscured by differences taken during the immediately preceding months by m sampling gear and variations in fish behavior. 1-m beam trawl. This size diffennee was greater than Major biases m abundance estimation can arise from would have been expected from growth alone and size selectivity of the gear, spatial distribution of suggests that CPUE indices were biased because mdividuals m niation to the gear, and behavior of fish smaller individuals were excluded from the catch.
Differences in mean length by year (Table 22) may also have differentially biased the trawl sampling. m The fixed Jocations of the otter trawl sampling sta.
- 60-' tions in relation to the habitat available to juveniles W
6 50j ' also may have affected catches. Movements of small 5 ' juveniles were probably influenced by factors such as ' E 405 water temperature and tide. Moreover, their availabil-8 30j ity to sampling gear in fall and winter appeared to. d g 2H
,[
have varied from week to week and year to year. Relatively large confidence intervals around the 3 c1 A-means were probably a consequence of this varia-5 3o): h_[
~
I tion. In contrast, variation was less in data collected is i8 8'o 8'2 8'4 B'6 B'8 9'O 9'2 E ~
- YEAR-CLASS Furthermore, sampling m summer occurred weekly -
during the same tidal stage and in areas known to be Fig. 32. Comparison between the late fall.carly winter preferred habitat of young winter flounder. Finally, a seasonal A.mean CPUE (solid line) of age-0 winter mixture of juveniles from a number of source areas ' flounder (all trawl monitoring program stations) and the most likely occurs throughout LIS during the winter, 1983-92 la:e summer Niantic River (stations LR and WA and could also have influenced measures of abundance combined) age O l m beam trawl median CPUE (dashed because they are dependent upon unknown contribu-line) for the 1976-92 year. classes- tions from different stocks. Winter Flounder 197
Age ljuveniles (late winier) was 1.9, marking the fourth straight year that relative-ly low values were recorded for this time series (Table Small winter flounder are incidentally captured each 26). Behavior of juvenile winter flounder largely year during the February April adult winter flounder influences their availability to sampling and apparent-surveys in the Niantic River. An annual median ly varies from year to year as a result of changing CPUE was calculated for winter flounder smaller than environmental conditions. Differential distribution 15 cm, which included mostly age-1 fish spawned (and, therefore, relative abundance) of small winter during the previous year; adjustments made to the flounder has been noted to occur between Niantic Bay catch data for the calculation of CPUE were similar to and River from year to year (NUSCO 1993). Trawl those previously discussed for adult fish. In some monitoring program (TMP) data from this spring, annual comparisons, data were restricted to stations I however, are not yet available for determining abun-and 2 in the navigational channel (Fig. 2) because the dance of winter flounder in Niantic Bay during the distribution of small winter flounder generally varied 1993 adult spawning season. A A-mean CPUE was more than for adult fish and, moreover, no tows were computed for winter flounder smaller than 15 cm made in the upper river from 1977 through 1980. taken by the TMP from January throught April at The 1993 median CPUE for age 1 juveniles taken stations outside of the Niantic River. This dme span , in the navigational channel of the lower Niantic River overlapped the spawning period and also served to ' was 4.3, which was a decrease from the CPUE of 5.6 increase sample size. Values of this index were then for 1992, but similar to the value of 4.9 for 1991 compared to the CPUE median for fish found within (Table 25). When tows from throughout the river the river during the spawning season (Fig. 34). ! were considered for the calculation, the median CPUE Generally, the catch of age-1 winter flounder in the TABLE 25. Annual 9.1 m ouer trawl adjusted median CPUE' of winter flounder smatter than 15 cm* taken in the navisadonal channel of the lower Mantic River durmg the 1976 through 1993 adult populadon abundance surveys. Tows Adjusted Median 95% confidence Coefficient - Survey Weeks acceptable number of CPUE interval for of year b sampled for CPUE' tows usedd cadmate - median CPUE skewness' 1976 7 98 154 20.0 19.0 - 20.0 2.77 1977 6 166 229 13.5 12.0 17.0 - 1.50 1978 6 129 156 21.6 15.0 25.0 1.59 1 1979 5 107 136 41.0 27.0 66.3 2.82 1980 5 110 145 49.3 345 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 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 t 1986 7 72 118 4.1 2.75.3 1.57 1987 5 41 50 5.0 4.3 - 6.7 2.08 , 1988 6 49 54 11.2 7.7 - 15.7 1.35 1989 7 50 54 7.9 4.0 + 11.9 1.19 1990 7 65 91 7.4 5.8 13.3 2.06 1991 6 45 60 4.9 3.36.5 2.55 1992 7 31 49 5.6 5.29.4 2.10 1993 7' 36 48 4.3 3.1 - 6.3 2.02 i
- Catch per standardized now (see Materials and Methcxis).
b Mostly age 1 fish, so predominant age class was produced 1 year before the survey year.
- Only tows of standard time or distance made in the savigational channel of the lower river were considered.
- Efrort equatized among weeks.
- 2eno for symmetricatly distributed data. .
.l 8
Because of low effort. data frczn the third week of sampling not used for the computancr.: of CPUE.
)
198 Monitoring Studies,1993
.- . - .. ~_
TABl.E 26. Companson of annual 9.1 rn ouer trawl adjusted median CPUE* of winter flounder smaller than 15 cmbtaken in the navigational channel of the lower Niantic River with those caught throughout the entire sampling area of the river during the 1976 through 1993 adult population abundance surveys. Navientinnal eMel ontv: Entire uma of river umnfed: Adjusted Median Adjustti Median Survey number of CPUE Coefficient of number of CPUE Coefficient of y ear
- town used* estimate skewnesa d tows used* cstimate skewness d 1776 154 20.0 2.77 231 14.4 2.84 1977 229 13.5 1.50 Insufficient tows made in upper river 1978 156 21.6 1.59 Insufficient tows made in upper river 1979 136 41.0 2.82 Insufficient tows made in upper river ,
1980 145 49.3 1.30 Insufficient tows made in upper river 1981 140 71.1 0.79 182 14.0 IM 1982 70 34.4 1.46 118 8.7 2.40 1983 77 43.0 0 55 238 11.5 1.80 1984 71 18.5 2.23 287 6.4 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 1988 54 11.2 1.38 312 3.7 3.03 1989 54 7.9 1.19 318 6.1 1.64 1990 91 7.4 2.06 320 2.0 5.00 1991 60 4.9 2.55 330 1.4 5.41 1992 49 5.6 2.10 406 2.0 4.58 1993 48 4.3 2.02 392 1.9 3.08 i
- Catch per standardtr.ed tow (see Materials and Methods).
- Mostly age.1 fish, so predominant age-class was produced ! year before the survey yesr.
- Effort equalind among weeks.
d Zero for symrnetrically distributed data. U 80-5 7oj river war relatively high while catch outside the river
! c0 ! '. . was low. This trend reversed in 1989 as catch in the m bay was the second highest of that series and showed < so :
l that most juveniles did not remain within or re-enter
'0i
" the Niantic River. As the number of small fish in the h 305 river declined to low levels in recent years, the relative 2 20 4 s 1 pI number outside the river increased. The CPUE of fish l 104 . T.]. ,
egh . found in the bay remained greater than that for fish
- 30: .
76 78 80 82 84 86 88 90 92
. F."2 . I taken in the river from 1990 through 1993. A small-CPUE index in the river may not necessarily indicate YEAR (JANUARY-APRIL) a continued decline in abundance, because even a Fig. 34. - Comparison between the annual January-April relatively small increase in catch from the much larger A-mean CPUE (solid line) for all trawl monitoring geographical area of Niantic Bay and nearby LIS g g g program stations except NR and the Niantic River (sts.
tions 1 and 2) spawning survey median CPUE (dashed M MhNWMWW l ' line) for winter flounder smaller than 15 cm from 1976 abundance of age-1 j.uvemles, perhaps as a result of through 1992. variable environmental conditions influencing their-behavior and availability to sampling, their abundance winter and early spring fluctuated less outside than indices remain generally unreliable predictors of future ; inside the Niantic River. In 1988 catch within the adult population size. j 1 1
)
WinterFlounder 199 l j l l
]
Comparisons among life-stages (107%). This was expected because much of the of wmter flounder year-classes compensatory mortality is believed to occur during this stage of development. Late .* ace Niantic River Abundance indices for various life-stages of the w'mter flounder larvae and juveniles had CVs of 83 to 1976 through 1993 year-classes of winter flounder 91%. Variability decreased to 71% during fall and discussed throughout this report are summarized in early v4nter after young left shallow inshore waterse Table 27. Coefficients of variation (CV) were used to An increase in CV to 91% for age-1 juveniles in the ; examine annual variability in these abundance indices Niantic River during the adult surveys was probably (Table 28). The CVs of all Niantic River winter related to the previously discussed annual differences flounder abundance indices increased over those given in distribution related to their behavior as well as from in NUSCO (1993). 'lhis was likely the result of near actual variation in year-class strength. Rothschild and , or all-time low abundance indices for spawners, egg DiNardo (1987) reported a median CV for recruitment i production, larvae, and juveniles, and a series high for indices of various marine fishes of 70%, although the fall-winter A-mean for age-0 winter flounder. various flatfishes had CV values mostly less than " Variability was lowest (CV = 60%) for the number of 75%. The CV for abundance of European flounder females spawning in the Niantic River and for associa. decreased from 172% (n = 9) in the larval stage to , ted egg production (56%). For the first three adult 99% (n = 8) for newly settled young to 80% (n = 8 - female age-classes, variability decreased from age-3 12) for both young in September and at age-1 (van der . (95%) through age-5 (74%). This likely reflected Veer et al.1991). As summarized by van der Veer variation in recruitment of year-classes as well as the (1986), the highest CV for yearly abundance estimates varying numbers of immature 3- and 4 year old fish of different life stages of plaice in The Netherlands present in the river each year. Miller et al. (1991) occurred during larval development in late winter (n = noted that interannual variability of many flatfishes 4, CV = 95%) and at first settlement of pelagic juve- _ appeared to decrease with age. Over all years, variabili. niles in spring following larval metamorphosis and ty among larval stages was greatest for Stage 2 larvae settling (9. 62%). Less variation was found for post-TABt.E 27. Comparison ofindices of abundance for various life-stages of winter flounder for the 1976 through the 1993 year. classes. Aduh in ket farval inMices Juverdle indices Female Annual Niantic River stadons (FebJun) MNPS Lower Lower River / bay Age-1 Year- spawners egg Stage 1 Stage 2 Stage 3 Stage 4 (EN) river river A mean CPUE class (Feb-Apr)produedan (3 mm) (3.5 mm) (6 mm) (7.5 mm) (27 mm) (May-hl)(Aug Sep)(Nov Feb)(Feb-Apt) 76 - - - - - - 854 - - 6.1 13.5 77 884 394.6 - - - - 567 - - 5.1 21.6 78 1,412 717.5 - - - - 754 - - 4.2 41.0 79 1,120 535 3 - - - 641 - - 4.2 493 80 903 424 3 - - - - LL45 - - 10.1 71.1 81 2,f49 1.383.1 - - - - 561 - - 7.7 4.4 82 2,752 1,596.8 - - - - 610 - - 19.6 43.0 83 1,869 1,082.0 - 749 408 56 1,215 32.7 10.0 66 18.5 84 871 501.6 2,601 1,501 573 67 917 18.8 63 7.4 23.6 85 928 565.2 6.26o 4,676 584 35 3t2 '33
, 7.0 8.1 4.1 86 655 436.7 1,279 176 301 14 310 33.8 13.8 11.7 5.0 87 85 2 531.6 3.218 829 1,036 48 315 59.2 17.9 4.8 11.2 88 1.279 866.9 14,491 4,469 1,531 210 419 613 60.0 3.6 7.9 89 984 716.2 12N3 3,976 s89 73 327 17.5 8.8 11 3 7.4 90 579 370.4 4,728 355 258 57 508 !$6.3 20.0 21.7 4.9 91 1,061 639.6 3,'t4 P 252 343 112 439 77.5 21.7 19.0 5.6 92 534 391.1 5,4~ 6 1,367 2,339 195 1,003 90.0 28.1 31.1 43 93 274 223.6 1,1 57 133 111 6' 130 10.6 5.0 - -
i I
- An approximadon based on cumulative geometne weekly mear's. Gompertz funedon could not be fit to the data as larvae were only collected danns 2 weeks of sampling.
200 Monitoring Studies,1993
TABLE 28. Coefficients of varianon (CV) for annual abundance indices
- of various tJe stages of Niande River winter flounder.
Number of life stage Abundance index used observadons CV Female spaners Annual standardized catch 17 60% Age 3 females Annual standardized catch 15 95 % Age-4 females Annual standardized catch 14 74 % Age-5 females Annual standardized catch 13 67 % Eggs Egg produedan index 17 56 % Stage I larvae a parameter of Gompenz functim 10 83 % Stage 2 larvae a parameter of Compenz function !! 1(TI% Stage 3 !arvie a parameter of Gompenz function 11 91 % Stage 4 larvae a parameter of Gompenz functim 11 83 % Age-O young Median CPUE at station LR (May-July) 11 85 % Age 4 yo:mg Median cpl!E at station tR (August Sept) 11 87 % Age 4 young Fall-winter A-mean at trawl stations 17 71 % Age I juveniles Median CPUE of fish < 15 cm in Niantic River 17 91 %
- Indices used correspond to those given on Table 27. except for age-3 through age 5 females.
larval young during mid-summer (9,30%) and for age- relationships between previously correlated indices 2 recruits (9, 35%). He attributed the decline in were strengthened (Tables 29 and 30). Among these variation of abundance of older juveniles to a density- were female spawners and egg produedon, which was dependent regulatory mechanism that operated during expected because calculation of the latter included and shortly after larval settlement. Both van der Veer female spawner abundance as part of the methodology - (1986) and Bergman et al. (1988) noted that recruit- of estimation. A significant positive correlation was ment variability in plaice in The Netherlands was also found this year between calcuhted egg production stabilized between years as a result of density-depen- and yolk-sac (Stage 1) larvae. Significant correlations dent regulatory processes (i.e., shrimp predation) on were found among most larval stage indices. The newly metamorphosed fish. The CVs for year-class abundance of larvae 7 mm and larger collected at strength of plaice in Swedish bays varied to a greater MNPS (stadon EN), howevet, was not significantly degree (67118%), which was thought related to tem- correlated with any of thejuvenile abundance indices, perature effects during the larval stage and rnore vari- Age-0 juvenile abundance during summer and late fall-able cmstacean predation on newly metamorphosed early winter were also correlated (see Fig. 32). This young in northern waters than in The Netherlands year the late fall-early winter 4-mean abundance index (Pihl 1990; Pihl and van der Veer 1992). was significantly negatively correlated with the abun-Relationships among abundance indices of winter dance of age-1 juveniles taken in the Niantic River flounder for the same year class are of interest for during the adult winter flounder surveys. The relation-impact assessment. Knowledge of the earliest possi- ship between these two indices was shown previously ble measure of relative year class strength is desirable (Fig. 33). The reasons for this inverse relationship because it enables predictions of future recruitment to and the change in patterns of abundance that occurred the adult stock, thus providing an early warning of during the mid-1980nm unknown. decreases in stock abundance. If indices for all life- If catch indices were assumed to be representative of stages are assumed to be accurately and precisely annual relative abundances, Niantic River winter measured each year, they should be correlated after flounder were found to be fully recruited only at about - applying appropriate time la;;s, except when processes age-5 (NUSCO 1990). Thus, age-3 or age-4 fish such as density dependent mortality or size selective probably should not be used as an index of year-class fishing resuh in a lack of colinearity between two con- strength because it is likely that only a fn etion of secutive life-stages. With the addition of data from these fish occur on the spawning grounds each year. 1993, several life-stage abundance indices of Niantic Furthermore, this fraction may vary from year to year. River winter flounder became significantly correlated A few correlation coefficients between the abundance (Spearman's rank-order correlation) this year and of female spawners at ages-3,4, and 5 and those for WinterFlounder 201 'l
-l 1
j TABLE 29. Matrix of Spearman's rsnk-order correlations among various wimer flounder spawning stock and larval abundance indices. Except for larvae 7 rnm and larger taken at the MNPS intakes, all cher indices refer to aduhs or larvae collected in the Niantic River. Adult egg Stage 1 Stage 2 Stage 3 Stage 4 Larvae at MNPS intakes Index* production larvae larvae larvae larvae (27 mm) Female 0.9387* 0.6000 0.4364 0.2727 0.4000 0.2378 l spawners 0.0001 " 0.0667 NS 0.1797 NS 0.4171 NS 0.2229 NS 0.3582 NS 17 10 11 11 !! 17 Aduh egg 0.6727 0.5000 0.4182 0.4000 0.0980 production 0.0330
- 0.1173 NS 0.2006 NS 0.2229 NS 0.7082 NS 10 11 11 11 17 Stage I 0.8061 0.6606 0.6849 4.0303 larvae 0.0049 " 0.0376
- 0.0289
- 0.9338 NS 10 10 10 10 .
Stage 2 0.7636- 0.4546 .o.0909 larvse 0.0062 " 0.1601 NS 0.7904 NS 11 11 11 Stage 3 0.6091 0.0818 larvae OM67
- 0.8110 NS 11 11 Stage 4 0.3636 larvae 0.2716 NS 11
- Indices used correspond to those given m Table 27.
- The three statistics shown in each correladon matrta element are:
correlation coefficient (r), 'i probability of a larger r (NS - not significant [p > 0.05). * - significant at p 5 0.05," - significant at p 5 0.01), and nurnber of annual observations (sample size). 7-mm and larger larvae at MNPS and some juvenile fishing effort, which may occur in overfished stocks. indices were significant (Table 31). The CPUE of Meanwhile, none of these life-stage indices can pres-age-1 fish taken in the river during the adult spawning ently be used as a reliable measure of year-class surveys was significantly correlated with age-3 female strength. spawners. However, the correlations were not signifi-cant for age-4 and 5 females. Significant negative Stock-recruitment relationship (SRR) correlations were found between both age 3 and age-4 , females and the age-O fall-winter A mean CPUE, but Sampling based estimates. Egg production the weakest of the negative correlations (not signifi- estimates from annual spawning were used to deter-- cant) was found between age-5 spawners and the fall- mine recruitment because the abundance of the other early winter juveniles, which should havt' been one of early life-stages have not been reliably correlated with the most reliable as females are fully recruited by this adult spawners. Both recruitment and the parental age. If negative correlations persist in future years, spawning stock indices were scaled to absolute popula-they could be interpreted as an indication of unknown tion size as described previously (see Absolute abun-processes operating after winter flounder become age-1 dance estimates, above). The resulting annual values that result in fewer adults being recruited in spite of were used with the Ricker SRR model as estimates of larger numbers of juveniles. Possibilities include adult female spawning stock and potential female variable discard mortality of juveniles in the commer. recruitment (Table 32). The addition of new catch data cial fishery; high rates of fishing; and non-random from the 1993 adult winter flounder survey and 202 Monitoring Studies 1993
~
t f ... t TABLE 30. Matrix of Spearman's rankerder correlations among various larval and juvenile winter flounder abundance indices. Niande River Iower river Lower river Fall-early winter Niantic River Stage 4 carly age-O late age-O river bay winter spring indea' larvae juveniles juveniles juveniles age ! juveniles MNPS intake 0.3636' O.4727 0.3091 -0.1778 R4485 , larvae 0.2716 NS 0.1420 NS 0.3550 NS 0.4948 NS 0.M09 NS (27 mm) 11 11 11 17 17 Niantic River 0.5727 a6818 0.6242 0.1030 Stage 4 0.0655 NS 0.0208
- 0.0537 NS 0.7770 NS ,
larvae 11 11 10 10 Lower river 0.8909 0.6485 4 2242 carly age-O 0.0002 " a0425
- a5334 NS juveniles 11 10 10 Lower river 0.7212- 4 2364 late age 4 a0186
- 0.5109 NS juveniles 10 10 Fall.early winter -0.5199 river. bay 0.0324
- age-O juveniles 17 l
- Indices used correspond to those given on Table 27.
- 7he three staditics shown in each correladon matrix element are:
concladon coefficient (r), probability of a larger r (NS . not significant [p > 0.05), * . significant at p 5 0.05, " . .significant at p 5 0.01), and number of annual observadons (sample size). ; P TABLE 31 Matrix of Spearman's rank-order comladons among vajous winter flounder larval and female spawner abundance indices. MNPS intake lower river lower river Fall-early winter Niantic River larvae early age-0 late age O river bay winter spring Index* (27 mm) juveniles juveniles juveniles age-1 juveniles Age 3 0360F 0.0000 0.1191 4 5952 0.7124 - female 0.1866 NS 1.0000 NS 0.7789 NS 0.0192
- 0.0028 "
spawners' 15 8 8 15 15 Age-4 0.3758 0.1071 4 1429 4 8889 0.5121 female Q!B54 NS 0.8172 NS 0.7599 NS 0.0001 " 0.0612 NS spawne rs" 14 7 7 14 14 Age.) 0.6154 -0.2571 0.3714 4 4319 0.1813 . female 0.0252
- 0.6228 NS 0.4685 NS 0.1405 NS - 0.5533 NS ;
spawners
- 13 6 6. 13' 13
- Early Ide history indices used conespond to those given m Table 27.
- Determined by applying an age length key (NUSCO 1989) to the length distribudm of annual standardized female abundances.
* '!he three statistics shown in each correladon matrix element are:
- conclation coefficient (r), a probability of a larger r (NS . na significant [p > 0.05], * - significant at p s 0.05," . significant at p 5 0.01), and numter of annual observadons (sample site).
l WinterFlounder 203 l l
.i
TA11LE 32. Armual NianUc River winter flounder stock-recmitment data based on indices of egg production for the 1977 through the 1989 year-ctasses with mean February water temperature and deviadons Up.6) frorn the mean. > Mean February Deviatim from Index of female Index of female IW water - mean February water Year class spawners (P)* recruits (R)* rado temperature (*C) temperature Um) 1977 20.o97 65,125 3.24 036 2.12 1978 36,544 45,750 1.25 1.09 139 1979 27,262 36,757 135 1.48 .l.00 1980 21,608 28.861 134 238 -0.10 1981 70,441 28,101 0.40 2.63 0.15 1982 81,324 32.708 0.40 1.56 -0.92 1983 55,104 35,874 0.65 3.74 1.26 1984 25,544 27,175 1.06 4.02 1.54 1985 28,789 25.666 0.89 236 -0.12 1986 22.241 21,062 1.08 338 0.90 1987 27#76 20,912 0.77 3.28 0.80 1988 44,t53 8.812 0.19 2.67 0.19 1989 36.478 3,194 0.09 3.24 0.76 Mean 38,205 29,415 0.77 2.48 CV 51 % 53 % 44 %
- Scaled number of female spawners and recruits frcm expected egg production; scaling factors used were 561,000 eggs per females and a multiplier of 28.571 to conven reladve abadance to an absolute populadon size. Indices of female spawners and recruits differ from those reponed in NUSCO (1993) because of data added from the 1993 adult winter flounder population survey and changes in the values of Zused in the cateuladans.
changes in the values of Z used in the calculation of for the deviations from the 1977 89 mean February potential recruitment resulted in some differences temperature of 2.48'C) is the solid-line curve. The between present estimates and those reported in outermost two dashed-line curves describe low recruit. NUSCO (1993), ment in the warmest year (1984: T Feb = +1.54) and The two-parameter SRR model (Eq. 6) was initially high recruitment in the coldest year (1977; Treb = fitted to the spawner and recruit data. The stock -2.12). growth potential parameter n (scaled as numbers of The a values determined this year from both the fish) was estimated as 2.329, having a standard error two and three parameter models decreased from corre-of 0.964 (41% of the parameter value). The two- sponding values reported during the past 4 years in parameter model estimates were used as initial values NUSCO (1990,1991b,1992a,1993). This variation for fluing the three-parameter SRR model with temper- could be caused by increasing fishing mortality rates ature effects (Eq. 7). This second fit produced an esti, on winter flounder in addition to the inherent instabil-mate for a of 1.977, with a standard error of 0.566, iry of parameter estimates fitted to small data sets. In which is 29% of the parameter value (Table 33). For particular, the influence of the 1988 and 1989 data the three-parameter model, the pammeter $, which was points on the estimate of a were illustrative of higher an estimate of the effect of February temperature recent exploitation (Fig. 35). Because of relatively deviations (Treb) frorn the 1977 89 mean of 2.48'C, high abundance of juvenile winter flounder frorr: the . was -0.412, an increase from the value of -0.357 1988 year-class, nurnbers of females were expected to reported in NUSCO (1993). The three-parameter SRR increase in 1992 and 1993 and form the bulk of the explained 51% of the variability associated with the spawning populationi However, these recruitment recruitment index. Relationships resulting from fits indices were much below expected values,likely the i of both Ricker models are shown in the central por- result of high fishing mortality rates in recent years. 1 tion of Figure 35 as follows: the unadjusted SRR The estimate of Ricker's parameter, which de- l (two parameter model: Eq. 7) is shown as the brokc> scribes the annual rate of compensatory mortality as a line curve and the three parameter curve (SRR adjusted function of the stock size is important in SPDM 204 Monitoring Studies,1993
TABII 33. Parameters of the Ricker stock recruitment model flued to data for Niantic River female winter flounder spawners from 1977 through 1989 and sane derived paints of reference. Model parameters and reference points Model osrsmeters (detemine3 frnm r umkrs of fiM: Fstimuted value Standard eng g* Go (compensatory reserve for unfished stock) 5,42 . - a (current compensatory reserve) 1.977 6 0.566 3.49 "
$ (stock-dependent compensatory rate) 2.523 X Igs 6.42 X 104' 3.93 **
$ (environmental [ temperature] effect) 4 412 0.1075 3.83 "
Thrived rsts of reference: Numters of fish hg4hs) Unfished stock equilibrium size (P,.p; called maximum spawning patential by Hnwell et al.1992) 66,988* 97.132 Present (through 1989) equilibrium size (Pm) 27,015* 27.015 F for Pm = 26.526 female spawners 1.01 - Estimate of entical stock aire (257 of maximum spawning potendal) - 24.283
- s.statisde for parameter esumate s 0 with d.f = n.3 = 10.
b laciudes the effects of recent explonadan rates. '
- Average weight of female spawner for unfished stock is 1.45 lbs and for current exploited stock is ! lb.
70 - 8,, y *77,.'..**,.......~........,,,""~.""~ M 3 60- /. o - 3 .. .....,'". g / 50-m / w *
. 78 ~..~.'
f 40-j ...".... e 79 *@ m [ 80 m 30-p~~- ' 82 f /e
,g s e 81 o / '
~
i i 4 w 20- :
! / 86
- 87 y /
o W
!i/ ' . . . * * . . . ' ' . . . . .*.88 . . . . . , . . . .. .~.. .. .~ .. -. .- .~. .~. .~. .~. ~ . .~
8 cc 30 !/, . ' . . ' o '
+ 89 p 0- i i i ' ' i > ' ' , , . - ' ' ' ' ,
g ' 20 30 40 50 60 70 80 9O 100 FEMALE SPAWNERS IN THOUSANDS Fig. 35. The Ricker SRRs for Niantic River winter flounder (see text for explanation of the four curves plotted). Calculated recruittnent indices for the 1977 through the 1989 year-classes are shown. WinterFlounder 205
simulations. The parameter estimate of 0.0000252 spawners refers to the sustainable or equilibrium size has remained fairly consistent since 1988. He value to which the stock could converge if present (through for $ (-0.412) was negative and although the relation. 1989) exploitation and other conditions remained ship between winter flounder recmitment and February unchanged. The calculated (Eq.10) value of F that temperatures remain unknown, February coincides would achieve equilibrium stock size was 1.01, which j with most spawning, egg incubation, and hatching. is much higher than the DEP estimates of F for those These processes, as well as larval growth, are all ' years. His difference can mostly be due to the lack of temperature-dependent. Buckley et al. (1990) noted age structure in Ricker's model, which causes fishing that the winter flounder reproductive process appears mortality to be concentrated in a single year for cach to have been optimized for cold winter temperatures year-class; winter flounder year-classes are exploited j followed by gradual spring warming. Adult acclima- during many years. As mentioned previously in the ; tion temperatures and egg and larval incubation temper. Materials and Methods section, these reference points ; ature affected larval size and biochemical composidon. derived from fishery data are only determmistic approx-Cold winters and warm springs produced the largest imations useful for comparative purposes across larvae in the best condition at first feeding. This stocks and, in this study, to compare to the correspond-favored good survival and may partly explain the ing and more realistic values derived through simula-observed correlation between cold years and strong tion using SPDM. year-classes of winter flounder. Townsend and Estimation of a for SPDM simulations. Cammen (1988) noted that the metabolic rates of The above stock-recruitment based estimates of a for pelagic consumers are niore sensitive to lower tempera- the Niantic River winter flounder provided an underesti-ture than rates of photosynthesis by phytoplankton, mate of the true slope at the origin for this stock. which bloom more in response to the amount of solar The method of calculating annual recruitment included radiation received. Therefore, an earlier bloom in a the effects of fishing on winter flounder age 2 and cold year has the possibility of lasting longer before older as well as the entrainment of larvae at MNPS. being grazed down by zooplankton. This allows for a Therefore, these direct estimates of a correspond to a greater contribution of organic matter to the benthos compensatory reserve diminished by existing larval-than in other years, benefiting juvenile demersal fishes entrainment and exploitation rates. The concept of that metamorphose just after the spring bloom of compensatory reserve in fishing stocks and the effect phytoplankton and have to outgrow various predators. of exploitation on the shape of the reproduction curve As noted previously, the effect of temperature on when the recruitment index is based on the exploited potential prey or predators of larvae and newly meta- stock was discussed by Goodyear (1977: Fig.1). morphosed juveniles, such as the sevenspine bay Thus,if tarval entrainment and fishing rates increase, shrimp, may be an additional means for control of the field estimates of recruitment will be smaller and population abundance. Strong year-classes of plaice so will the estimates of a (i.e., the " remaining" were also associated with cold winters, likely because compensatory reserve). To assess impacts appropriate-the predatory brown shrimp (Crangon crangon) suffers ly, the inherent potential of a stock to increase in the - high mortality or migrates out of plaice nursery areas absence of fishing and plant einects must be deter-(Zijlstra and Witte 1985; van der Veer 1988; Pihl mined. Crecco and Howell (1990) investigated the 1990; Pihl and van der Veer 1992), possibility of using indirect methods to estimate the In addition to the above SRR parameters directly true a parameter (i.e., for the unfished stock when F = estimated from stock-recruitment data through 1988 0). Rey used four indirect methods (Cushing 1971; (Fig. 35), Table 33 includes four derived biological Cushing and Harris 1973; Longhurst 1983; Hoenig et reference points. Ricker's stock-at replacement, or al.1987; Boudreau and Dickie 1989) based on different P,ep (Eq. I!), was estimated at 66.988 female spawn- life history parameters. Because these methods do not ers and is the unfished equilibrium spawning stock depend upon direct estimates of recruitment, they size, also known as the maximum spawning potential avoid biases caused by changing fishing rates and (MSP). This reference point, expressed in units of provide independent means of validating SRR-based biomass as 97.132 lbs, is the basis for the critical estimates. The present study used a Ricker SRR a stock size (25% of MSP) below which the stock is parameter estimate derived from the value of 3.74 in considered overfished (flowell et al.1992). The biomass units reported by Crecco and Howell (1990: present equilibrium size PE (F) (Eq. 9) of 27,015 Table 2). This value was re-scaled for numix:rs of fish 206 Monitoring Studies,1993
1 I on the basis of the following relationship: unfished stock as a starting point for simulations also abiomass = a /(mean weight per mature female fish) has other advantages, depending upon the particular (19) scenario selected. For example, simulation in this where the mean weight was calculated for a population report includes initially moderate fishing rates that are at equilibrium and one for which only natural mortali- much lower than those affecting the data on which the ty was assumed to have occurred (i.e., the unfished regression estimate of a was based. The data-based population). A mean weight of 1,45 lbs per female estimates of the other two SRR parameters ( and Q), which do not depend upon fishing and entrainment spawner for the Niantic River unfished winter flounder stock was calculated (Table 34) using population data rates, were used in the population simulations as previously reported (NUSCO 1990). Using this mean given in Table 33, weight, the re scaled a parameter for this study was obtained as: MNPS impact assessment , a0 = abiomass-(mean weight) = 3.74-(1.45 lbs)
= 5.42 (20) Larvalentraintnent This parameter describes the inherent potential of a stock for increase because the natural logarithm of a Estimates of larval entrainment at MNPS.
is the slope of the SRR at the origin for the unfished The number of winter flounder larvae entrained in the ,
~
stock (Ricker 1954) and that slope, in turn, condenser cooling water of MNPS is the most direct corresponds to the intrinsic rate of natural increase of measure of potential impact on the Niantic River the population (Roughgarden 1979). Since the slope winter flounder stock. Annual totals of entrained of the SRR at the origin decreases with increasing larvae were related to larval densities in Niantic Bay exploitation rates, it is useful to think of a as the and plant operations (cooling water volume). Nearly
" remaining growth potential" or " growth reserve" of all winter flounder larvae were collected at station EN ,
the stock. Consequently, the large difference between from February through June, with most (> 90%) the derived value of a (5.42) and the direct regression found in April and May. The entrainment estimate for estimate of a (1.977; Table 33) reflects the different 1993 (45,1 million) was the smallest after 1986, growth reserves of unfished and highly exploited when three-unit operation began, and was among the stocks of winter flounder, respectively, Using an smallest of the 18-year period since 1976 (Table 35). TABl E 34. Biomass calculations for the Niantic River winter flounder female spawning stock at equilibrium based on an instantaneous natural mortabry rate of M = 035 and an insuniancous fishing mortahty rate of F = 0 (virgin stock). Female Number of Weight of Eggs per Spawning stock Egg population Frsction mature rnature females mature bicmass production Age size mature females Obs per fish) female Obs) (millions) 2 1,000.00 0.00 0.00 - . . 0.000 3 704.69 0.08 5638 0.554 223,735 31.23 12.613 4 496.59 036 178.77 0.811 378.584 144.98 67.680 5 349.94 0.92 321.94 1.088 568,243 350.27 182.942 6 246.60 1.00 246.60 1377 785,897 339.56 193.800 7 173.77 1.00 173.77 1.645 1,004,776 285.86 174.6N 8 122.46 1.00 122.46 1.873 1,201,125 229.36 147.086 9 86.29 1.00 86.29 2.057 1,366,951 177.51 !!7.959 10 (4 81 1.00 60.81 2.203 1,502,557 13337 91371 11 42.55 1.00 42.85 2304 1,598,597 98.73 68.503 12 30.20 1.00 30.20 2.390 1.682,208 72.17 50.798 13 21.28 1.00 21.28 2.461 1,754,800 5237 37342 14 15.00 1.00 ' 15.00 2.516 1,809,000 37.73 27.127 15 10.57 1.00 10.57 2.552 1,845,800 26.97 19.505 Total 3,361.05 1,36691 1,980.71 1,191329 Mean weight per mature female fish = (1,980 lbs + 1,367 mature females) = 1.45 lbs (37.6 crn fish) Mean fecundity (virgin stock) = $71,548 eggs per female spammer WinterFlounder 207
TABLE 35. Annual abundance index (a parameter of the Gompertz function) with 95% confidence interval of winter flounder larvae in entrainment samples and total annual entrainment estimates during the larval season of occurrence, and the volume of seawater entrained at MNPS cach year from 1976 through 1993 during an 1364ay period from February 15 through June 30. a Standard 95% confidence Number entrained Seawater volume 6 3 6 Yeer parameter error interval (X 10 ) entrained (m X 10 ) 1976 1,656 32 1,588 1,724 107.6 662.8 1977 751 47 650 - 852 31.2 585 6 1978 1.947 352 1,186 - 2,706* 87.4 490.9 1979 1,296 81 1,121 1,470 47.7 474.1 1980 2,553 37 2,475 - 2,632 175.7 633.3 1981 1,163 23 1,113 1,213 47.7 455.2 1982 2,259 36 2,184 - 2,334 170.4 674.1 1983 2,966 21 2,921 - 3,012 219.3 648.0 1984 1,840 47 1,741 1,939 88.1 573.8 1985 1,585 48 1,483 1,686 83.3 528.1 1986 903 31 837 - % 8 130.6 1,353.4-1987 1.194 23 1.145 1,242 172.0 1,323.6 1988 1,404 42 1,315 - 1,493 193.3 1,381.7 1989 1,677 13 1,650 1,704 175.0 1,045.9 1990 1,073 25 1,021 1,125 138.8 1,302.7 1 1991 1,149 18 1,110 - 1,189 121.3 934.4 1992 3,974 76 3,812 - 4,136 513.9 1,199.3 1993 328 23 280 377 45.1 1,412.3 Even though the seawater volume for 1993 was the were found between the density of winter flounder largest reported during larval winter flounder occur- larvae 7 mm and larger taken at EN and the age-0 rence, the low larval abundance in Niantic Bay account- abundance indices (Table 30). Furthermore, the signif- .; ed for this reduced entrainment estimate. As in previ- icant correlation coefficients were positive, implying ous years, Stage 3 larvae predominated in entrainment no apparent entrainment effect. In general, even collections. In 1993, the percentages of each develop- negative correlations between annual entrainment and mental stage entrained were 5% for Stage 1,16% for abundance of early life history stages do not necessar-Stage 2,70% for Stage 3, and 9% for Stage 4, and ily imply an entrainment impact unless positive were similar to previous years. Overall percentages correlations can be found between those early life for 1983-92 were 3% for Stage 1,22% for Stage 2, history stages and mature female fish. 64% for Stage 3, and 11% for Stage 4 of Mass balance calculations. Themagnitudeof development. the impact of entrainment on the Niantic River winter Effect of entrainment on a year class. To flounder stock depends upon how many of the determine the effect of winter flounder entrainment on entrained larvae originated from this stock. Hydrody-a year-class, the relationship between entrainment namic modeling (NUSCO 1976) and current drogue estimates and various indices of juvenile abundance studies (NUSCO 1992b) showed that much of the were examined. Annual entrainment estimates were condenser cooling-water used by MNPS enters Niantic significantly correlated with two abundance indices of Bay from LIS. Other stocks are known to spawn both juvenile winter flounder (Table 36). These were for to the cast and west of the bay and results from tidal age-O fish taken in late summer at station LR and studies also indicated that a number of winter flounder during late fall-carly winter at the TMP stations. larvae enter Niantic Bay from LIS (NUSCO 1992a, However, the abundance of young at LR in early 1992b). To determine if the number of winter flount i summer, which immediately follows the larval der larvae leaving the Niantic River could support the l entrainment season, was not significantly correlated number of larvae observed in Niantic Bay each year, with estimated entnunment. Although significant, the mass-balance calculations were made for 1984 through form of the relationships between the entrainment 1993; eight of these years (1986-93) occurred during estimates and these two age-0 abundance indices was three-unit operation, The results determined for each , not obvious (Fig. 36). No significant correlations 5-day period in 1993 are provided as an example of I l 1 208 Monitoring Studies,1993 l i
TABLE 36. Spearman's rank order correladons between the annual estimates of larval winter flounder entrainment at MNPS and the abun-dance indices of several posbentrainment early hfe history stages. Lower river tower river Fau carly winter Niantic River Apparent larval en .y age-O late age-O river-bay winter spring survival Index* juvenilen juveniles juveniles age 1 juveniles rate Annual 0.52735 0.6455 0.5675 -0.2514 03237 estimate of 0.0956 NS 0.0320* 0.0175
- O3304 NS 0.2050 NS entrainment 11 11 17 17 37
- Indices used correspond to those given on Table 27, except for the apparent survival rate, which is the age 1 index divided by the index of 7 mm and larger larvae in Niantic Bay, b The three statistics shown in each correlation matrix element are correlation coefficient (r),
probability of a larger r (NS not significant [p > 0.051,
- significant at p 5 0.05). and number of annual observations (sample size).
35 M : these calculations (Table 37). Results for other years y 30.00 4 . were provided in NUSCO(1993). i!; 25.00 4 ' During the 1993 larval season, the sign of the term 8 . 5 day change shifted from positive to negative when 5 2000i . the estimated number oflarvae in Niantic Bay started E 15.00 4 to decline during a 5-day period beginning on May 6
- (Table 37), Also, in late February the sign of the h 10.00 4*
a 50 : S. . Source or Sink term changed from negative to posi-3 tive. A negative Source / Sink term indicated a net loss O'00 ' , , , i i i of larvae from Niantic Bay during the first part of the 0.000 10 000 20.000 30.000 40.000 50.000 60.000 larval season. During the'5 day period starting on ENTRAINMENT ESTIMATE (TENS OF MILLIONS) about February 25, the Source or Sink term became positive, an indication that larvae from other sources (i.e., LIS) were required to support the change in larval abundance and balance the equation. 'Ihe timing so 00 - . of this change in the Source or Sink term in 1993 was earlier than in previous years (NUSCO 1993) and may 5 Q 50 00 : be due to the low larval abundance in the Niantic -
40.00i '
River (Table 14), which serves a source of larvae in k the mass-balance calculation. During peak entrain-g 30 004 . rnent (April and May), fewer larvae were entrained S 20.00 i ' than were imported from LIS, indicating that sources 5 . other than the Niantic River provided larvae found in
$' 10 00 i , . Niantic Bay.
4 o,co - , , , , , , During each 5-day period the proportion.of 0.000 10 000 20.000 30.000 40 000 50.000 60.000 entrained larvae from the Niantic River was esdmated ENTFMINMENT ESTIMATE (TENS OF MILLIONS) from the rado of larvae entering the bay from the river (FromNR) to the total input from both sources Fig. 36. Relstionship between the annual entrainment (fromNR + Source or Sink). This proportion was estimate of winter flounder larvae at MNPS and the late applied to the total number entrained in that 5-day fall carly winter seasonal A-mean CPUE of age-O winter period to estimate the number entrained from the flounder from all trawl monitoring program stations Niande River. During 5-day periods when there was a (TMP) for the 1976 92 year classes, and between the net loss (negadve Source or Sink term) or when the entrainment estimate and the median CPUE of age-O , winter flounder taken at station LR in the Niantic River Propordon from the river was greater than one, all during late summer for the 1983-92 year-classes. larvac entrained were assumed to have on,ginated from - WinterFlounder 209
l TABLE 37. Results of mass-balance cala21stions for each $<fsy period in 1993. Number Loss due Number from the Number to the Start of 5. day entrained to mortality Niantic River Niantic River 5 dsy change (Ent) (Afort) (FromNR) (ToNR) Source or Sink 6 6 8 6 period (X 10 ) (X 10 ) (X 10') (X 10 ) (X 10') (X 10 ) 2 15 0.0* 0.0 0.0 2.7 0.0 -2.7 . 2 20 0.0 0.0 0.0 43 0.0 -43 ! 2 25 0.0 0.0 0.0 5.8 10.4 43 I 342 0.0 0.0 0.0 6.9 10.4 3.6 3G 0.1 0.0 0.0 7.5 10.5 3.1 3 12 0.2 0.0 0.1 7.6 10.6 33 3-17 03 0.1 0.1 7.2 10.8 4.1 3 22 0.4 03 0.2 6.5 11.2 5.5 3 27 0.5 0.6 0.4 5.7 11.6 73 4 01 0.5 1.0 0.4 4.9 12 2 9.2 446 0.5 1.6 0.5 4.1 12.7 11.2 4 11 0.5 2.4 0.7 3.4 13.2 13.4 4-16 0.4 3.0 0.8 2.8 13.7 15.0 4 21 03 3.5 1.0 2.4 14.1 16.4 4-26 0.2 33 1.1 2.0 14 3 16.9 541 0.0 3.7 0.9 1.6 14.4 17 3 5 06 -0.1 3.8 0.7 1.4 14.4 17.4 5 11 -0.2 3.6 0.9 1.2 14 3 17.4 5 16 -0.2 33 0.7 1.0 14.1 16.8 5 21 -03 2.9 0.7 0.9 13.9 16.2 5 26 -03 2.6 0.7 0.8 13.6 15.7 5.31 -03 23 0.5 0.8 13 3 15.1 6 05 -03 2.0 0.5 0.7 . I3.0 14.5 6 10 -03 1.7 0.4 0.7 123 13.9 6-15 -03 1.4 0.4 0.6 12.5 13.4 6 20 -0.2 1.1 03 0.6 12.2 12.8 6 't$ -0.2 1.0 03 0.6 12.0 12.5
' Due to rounding, any zero value represents less than 50.0001arvae.
the Niantic R.iver. This estimate was conservative, The potential impact of larval entrainment to the because the results of a dye study and larval dispersal population depends upon the age of each larva at the modelling (Dimou and Adams 1989) showed that only time it is entrained. Older individuals have a greater about 20% of the water discharged from the Niantic probability to contribute to year-class strength than River passed through MNPS during full three-unit younger ones. Therefore, the estimated number of operation. Estimates of annual total entrainment and each developmental stage entrained during each 5-day the annual number entrained from the Niantic River period was based on the proportion of each stage were determined by summing over all 5-day periods, collected at station EN. By applying the proportion Based on mass-balance calculations for data collected of entrainment attributed to the Niantic River in 19M-93, about 11 to 35% of winter flounder larvae (FromNR / [FromNR + Source or Sink]), the number entrained by MNPS originated from the Niantic River of larvae in each stage was allocated to each of the two (Table 38). For 1993, the estimated number oflarvae sources (Niantic River or LIS) for every 5-day period. entrained that originated from the river was much The annual number of each larval stage entramed from - - lower than previously reponed (NUSCO 1993), poba- each somre was estimated by summing over all 5-day : bly due to low abundance in the river ar.d the low total periods (Fig. 37). Most of the Stage 3 larvae (the entrainment estimate (Table 35). predominant stage entrained) originated from sources 210 Monitoring Studies,1993
i TABLE 38. Esdrnates of total number of larval winter flounder entrained, number of larvae entrained from the Niande River, and the percent-age of total entrainment auributed to the Niande River for 1984-93. Niande River % entrainment Total entraintnent larval entrainment attributed to 6 8 f; Year (X 10 ) (X 10 ) the Niande River 1 [ 1984 88.1 31.0 35.2 1985 83 3 27.7 333 1986 130.6 25.5 19.5 I 1987 172.0 39.9 23 2 f 1988 1933 39.0 20.2 l 1989 175.0 33 0 18.9 l
- l. 1990 138.8 36.3 26.2 i L 1991 1213 33.1 273 )
j? 1992 513.9 79.1 15.4 ; l 1993 45.1 4.8 10.6 i l l other than the Niantic River. As mentioned previous- three unit operation. Therefore, for full three-unit l ly, some of the larger larvae from other areas may operation,20% of the daily density of Stage I larvae '] have entered the Niantic River during flood tides and at station C were used as an estimate of Stage 1 larval l caused the increased frequency noted in the larger size- entrainment from the Niantic River. During periods ' classes (Fig.18). Results from a special bay wide of reduced plant operation, estimates were proportional-sampling during 1991 (NUSCO 1992a) showed that ly reduced based on daily water volume use. in April and May, when f bout 75% of Stage 3 larvae Entrainment esdmates for Niantic River Stages 2,3, were entrained, more tan ae entered Niantic Bay from and 4 !arvae were from the results of mass-balance LIS cast of Millstone Point and passed by the MNPS calculations, which used entrainment sampling densi-intakes during a flood tide than were flushed out of the ties. The estimated percentage of the Niuntic River bay to LIS during an ebb tide. Therefore, greater winter flounder production entrained annually since j densities of Stage 3 larvae w cre expected at station EN 1984 ranged from about 4 to 21.1% and had a geomet- J during a flood tide than during an ebb tid. This w,s ric mean of 8.5%. Thus, based on several special' confirmed in NUSCO (1993), wnere significantly (p $; studies (NUSCO 1992a,1992b) and the empirical 0.05) girater Stage 3 densities found in April and May I mass balance calculations, a large number of larvae . from 1983 through 1992 at station EN were from entrained at MNPS likely came from areas other than collections made during flood tides as compared to ebb the Niantic River, 1 tides. The above mass-balance calculations were based on Estimated production loss from the actual daily condenser cooling water volumes. To de- l Niantic River stock. Estimates of larvae termine the production loss for projected full (100% l ' entrained by stage from the river were compared to caprity) three unit operations, these calculations were annual abundance estimates for each larval stage in the recomputed based on a maximum daily condenser Niantic River to determine the percentage of produc- cooling-water volume of 11.1 million m3. day'I (Table tion loss from the Niantic River stock (Table 39). 39). To increase the time-series, three-unit operation . Estimates of Niantic River Stage I larvac entrained was simulated to include 1984 and 1985, prior to Unit were calculated from daily abundance estimates (Eq. 3) 3 start.up. Estimated annual percentages of the at station C, following an evaluation presented in Niantic River winter flounder production that would NUSCO (1993). This study indicated that entrain- have been entrained since 1984 under simulated three-ment sampling may underestimate Stage I larval unit operation ranged from 5.2 to 23.9% (geometric abundance because of net extrusion. Based on dye mean = 11.5%). These estimated annual reductions in studies (Dimou and Adams 1989),20% of the Niantic . year-class strength were used in impact assessment River discharge passes through MNPS during full simulations with the SPDM as described below.- WinterFlounder 211
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k 302 202
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0 -' i i i I O -- - I A J l 1 l 1 2 3 4 1 2 3 4 { 80 -- 1990 - 80 - 3ggg E60 - 60 .- y 40- 40 - g - 20 - s g 20-
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W l I i l 0 l I l l 1 2 3 4 1 2 3 4 4 ~ 30 1992 7 1993 25 - E300 _ - 7 y . 20 - g 200 - 15 - K . 10 - g 100 - W 0 " bIi # 0 - I~~ - I i .I l l 1 1 2 3- 4 1 2- 3 4 STAGE STAGE Fig. 37. Estimated number of winter flounder larvae entrained at MNPS by developmental stage from the Niantic River and I other soures, based on mass-balance calculations for 1984 through 1993. (Note that the vertical scales differ among the i graphs). 212 Monitoring Studies,1993
.I i
i l 1 l l TAllLE 39. Estimated abundance of winter flounder larvae in the Niantic River and the number and percentage of the production entrained fran the Niandc River by developmental stage for 1984.93. Numbers of larvae from the Niande River were based on the most recem mass- l balance calculadons. Projected full MNPS Agpal MNPS onentine mnitieme three. unit onenthe ermonime Niande River Entraintnent from Entraimnent from Suge of abundance
- the Niantic Rive / % of the the Niantic River % of the 8 8 Year development (X 10 ) (X 10 ) producdan (X 10') - producdon 1984' Stage 1 2864 103 0.4 22.6 0.8 Stage 2 685 14.6 2.1 313 4.6 Stage 3 337 13.5 4.0 33.2 9.9 Stage 4 235 2.7 1.1 7.8 33 Total 41.1 7.6 95.1 18.6 1985* Stage 1 3228 15.6 0.5 44.2 1.4 Suge 2 773 17.3 2.2 43.2 5.6 Slage 3 380 6.6 1.7 14.4 3.8 S'. age 4 265 03 0.1 8.8 03 Totat 39.8 4.6 102 6 11.1 1986 Stage 1 2494 11.6 0.5 14.4 0.6 Stage 2 700 6.9 1.0 7.6 1.1 Stage 3 366 14.2 3.9 14.8 4.0 Suge 4 255 3.8 1.5 4.0 1.6 Total 36.5 6.8 40.8 73 1987 Suge 1 3036 34.4 1.1 39.8 13 Stage 2 853 14.7 1.7 17.1 2.0 Stage 3 445 22.8 5.1 23.8 53 Stage 4 311 1.7 0.5 1.8 0.6 Total 73.6 83 82.5 9.2 19AB Stage 1 4951 83.7 1.7 92.1 1.9 Suge 2 741 93 13 9.9 13 Stage 3 267 24,1 9.0 25.9 9.7 Stage 4 192 1.4 0.7 1.4 0.7 Total 52.8 12.7 129.3 13.6 1989 Suge 1 4091 66.5 1.6 84 3 2.1 Sta8e 2 570 11.0 1.9 13.9 24 Stage 3 ILS 18.7 9.9 23.1 12 3 Stage 4 126 a4 03 04 0.5 Total %.6 13J 121.9 17.3 1990 Suge 1 2115 33 2 1.6 36.7 1.7 Stage 2 869 59 0.7 7.1 0.8 Suse 3 239 26.2 11.0 29.8 12.5 Stage 4 206 33 1.6 3.8 1.8 Total 68.6 14J 77.4 16.9 1991 Stage 1 3653 8.0 0.2 13.0 0.4 Stage 2 2549 3.4 0.1 4.8 0.2 Stage 3 715 25 3 33 33.4 43 Stage 4 628 4.2 0.7 5.5 0.9 Total 40.9 43 56.7 . 5.7 WinterFlounder 213
TABLE 39. (cont). Projected full MNPS Actual MNPS menine emdatione th ee-uait wrnCn, conditienc Niantic River Entrainment from Entisinment from Stage of abundance
- the Niantic River b % of the the Niantic River % of the 8 8 8 Year development (X 10 ) (X 10 ) production (X 10 ) production 1992 Stage 1 2234 23.0 1.0 28.6 13 Stage 2 936 103 1.1 11.6 1.2 Stage 3 344 54.7 15.9 61.5 17.9 Stage 4 276 8.5 3.1 9.8 3.5 Total 96.5 21.1 111.5 23.9 1993 Stage 1 1277 11.7 0.9 13 3 1.0 Stage 2 660 0.9 0.1 1.2 0.2 Stage 3 119 3.2 2.7 3.9 33 Stage 4 83 0.5 0.6 0.6 0.7 Total 163 43 19.0 5.2 Geometric mean 8.5 11.5
' Abundance estimates for 1984-89 were fram Crecco and flowell (1990) and those for 1990-93 were calculated by NUSCO staff. b Entrainment estimates attributed to the Niantic River are higher than those in Table 38 due to adjustments made for Stage 1 entrainment.
- Ahhough only MNPS Units 1 and 2 operated in 1984 and 1985, the projected values assume full three-unit operation for all years.
Stochartic simulation of the Nianfic a larval winter flounder season as it had in the past. River winterflounder Stock Expected changes in the values of F over time were determined after consultation with DEP Marine Fisher-Model simulation of MNPS impact. 'Ihe les (V. Crecco and P. Howell, CT DEP, Old Lyme, initial input data used to run the SPDM were described CT, pers. comm.) and reflect recent clunges in regula-in the Materials and Methods section (Tables 15; tions to considerably reduce F (see Table 2). Figs. 5-7). The model accessed a secondary input Simulation results. The stochastic baseline file,which included fishing (plus impingement) rates generated for impact assessment purposes describes the and the larval entrainment losses assumed for each female spawning stock sizes and annual variability of year of the simulation (Table 40). The combined Niantic River winter flounder since 1960 and includes mortality of fishing (F) and impingement (IMP) was only the effect of fishing. Because the baseline stock used only during the simulation period (1971-2025) projection included no power plant effects, it was used that corresponded to MNPS operation. Rates of larval as the reference against which the impacted stock entrainment (ENT) for 1971-93 were based on actual projection was compared. Therefore, the baseline' MNPS cooling-water flow and entrainment rates for needed to be a fair representation of past and projected Niantic River winter flounder larvae during three-unit trends of the local winter flounder abundance. Accord- , operadon as derived from the mass-balance calcula- ing to the simulation schedule (Table 40), nominal , tions discussed above. Entrainment rates shown in fishing rates started at F = 0.40, remained unchanged Table 40 for 1994 through 2025 were based on random- through the 1960s, increased gradually to 0.62 in ized values of ENT and nominal plant cooling-water 1988, and thereafter increased more rapidly to a maxi-flow, which also depended upon the number of units rnum rate of 1.31 in 1991 (see also Fig. 6), Note that i remaining in operadon in a particular year. The the tabled rates included an additional mortality equal values used in simulation years after 1993 were gener- to 0.01 that accounted for fish impingement during ated by randomly re-sampling those calculated through years of MNPS operation. After 1991 and as a result 1993 and adjusting them to account for varying frac- of proposed regulatory changes to the commercial tional flows for each unit and season. For this pro- fishery, F was projected to decrease fairly substantially cess,it was assumed that MNPS would operate during through the late 1990s, reach a low of 0.50 in 2001, 214 Monitoring Studies,1993 i i
T ABLE 40. Schedule of conditional entrainment (ENT) and fishing (F) mortalities with adjustments for impingernent (IMP) and fishing discard rr ortslaes as implemented in the SPDM simulatims.
% of year class reduction
'nrne Sunulation based on calculated or N<xninal F Fractional fishing discard F for :
step year simulated ievels of EN"I' (plus IMPf Age 1 Age-2 Age 3 A ge-4 0 1960 0.0 0.40 0.0360 0.2400 0.4000 0.4000 1 1961 0.0 0.40 0.0360 ' O.2400 0.4000 0.4000 l 2 1962 0.0 0.40 0.0360 0.2400 0.4000 0.4000 i 3 1963 0.0 0.40 0.0360 a2400 0.4000' a4000 i ! 4 1964 0.0 0.40 0.0360 0.2400 - ; 0.4000 0.4000 5 1965 0.0 0.40 0.0360 0.2400 0.4000 0.4000 6 1966 0.0 0.40 0.0360 0.2400 0.4000 0.4000 l 7 1967 0.0 0.40 0.0360 a2400 a4000 0.4000 8 1968 0.0 0.40 0.0360 0.2400 - a4000 a4000 9 1969 0.0 0.40 0.0360 0.2400
)
0.4000 a4000 l 10 1970 0.0 0.40 0.0360 - a2400 0.4000 0.4000 11 1971 0.1530 X ENT value 0.41 a0360 0.2400 a4000 0.4000 12 1972 0.2262 X ENT value 0.42 0.0369 0.2460 0.4100 Q4100 13 1973 n0767 X ENT value 0.43 0.0378 0.2520 0.4200 0.4200 14 1974 0.1895 X ENT value 0.44 a0387 0.2580 0.4300 0.4300 15 1975 0.2262 X ENT value 0 45 0.0396 0.2640 0.4400 0.4400 16 1976 0.4421 X ENT value 0.46 0.0405 0.2700 0.4500 0.4500 .l 17 1977 a4232 X ENT value 0.47 aN14 0.2760 0.4600 0.4600 l 18 1978 0.3018 X ENT value 0.48 0.N23 0.20 a4700 0.4700 19 1979 0.3133 X ENT value 0.49 l 0.N32 0.2880 0.4800 a4800 20 1980 0.4810 X ENT value 0.51 0.N50 0.3000 0.5000 a5000 21 1981 0.2873 X ENT value 0.53 0.0468 0.3120 15200 0.5200 22 1982 0.4857 X ENT value 0.56 0.0330 0.2695 (,5500 0.5500 23 1983 0.4675 X ENT value 0.58 0.0342 0.2451 0 5700 0.5700 24 1984 7.6 0.60 a0354 0.2537 f.5900 0.5900 25 1985 4.6 0.61 a0360 a2160 J.6000 0.6000 26 1986 6.8 0.63 a0372 a2232 0.6200 0.6200 27 1987 8.5 0.64 0.0378 a2268 0.6300 0.6300 28 1988 12.7 0.63 0.0372 0.1116 0.6014 0.6200 29 1989 13.8 0 86 0.0510 0.1530 0.8245 - 0.8500 30 1990 14.8 1.04 0.0618 ' a1854 - R9991 1.0300 31 1991 4.3 1.31 0.0780 0.2340 1.2610 1.3000 32 1992 21.1 1.18 a0702 0.2106 1.1349 1.1700 33 1993 4.3 1.18 0.0702 0.1170 a9594 1.1232 34 1994 Ul, U2, U3 flow X ENTvalue 1.00 0.0594 0.0693 a5445 G8910 35 1995 U1, U2, U3 flow X ENT value 0.77 0.0456 0.0532 0.4180 0.6840 36 19 % Ul, U2, U3 flow X ENT value 0.75 0.N44 a0518 a4070 0.6660 37 1997 U1, U2, U3 flow X BT value 0.70 0.N14 0.N83 a3795 0.6210 3P 1998 UI, U2, U3 0ow X E. Y r value 0.65 0.0384 0.0448 0.3520 a5760 39 1999 UI, U2, U3 flow X ENT value 0 60 0.0354 0.0413 0.3245 0.5310 43 2000 Ul, U2, U3 flow X ENT value 0.55 0.0324 0.0378 0.2970 0.4860 41 2001 U1, U2, U3 flow X ENT value 0.51 0.0300 0.0350 0.2750 0.4500 42 2002 UI, U2, U3 flow X ENT value 0.51 0.0300 ".0350 0.2750 0.4500 43 2003 Ul, U2, U3 flow X ENT value 0.51 0.0300 .0350 0.2750 0.4500 44 2004 U1, U2, U3 flow X ENT value 0.51 0 0300 - 0.0350 0.2750 0.4500 45 2005 Ul, U2, U3 flow X ENT value 0.51 0.0300 0.0350 0.2750 a4500 46 2006 Ul, U2, U3 flow X ENT value 0.51 0.0300 0.0350 a2750 0.4500 47 2007 Ul. U2, U3 flow X ENTvalue 0.51 0.0300 0.0350 0.2750 0.4500 48 2008 Ul. U2, U3 hw X ENT value 0.51 a0300 0.0350 0.2750 a4500 49 2009 Ul, U2, U3 hw X ENT value 0.51 a a100 0.0350 a2750 0.4500 50 2010 U1. U2, U3 flow X ENTvalue 0.51 0.0300 0.0350 o U50 0.4500 51 201I U2, U3 flow X ENTvalue 0.51 0.0300 0.0350 o2750 0.4500 52 2012 U2, U3 flow X ENT value 0.51 0 0300 0.0350 0.2750 0.4500 WinterFlounder 215
TABII40. (continued).
% of year-class reduction Time Simuladm - based on calculated or Nominal F Fractional fishing discard F for :
step year simulated ievels of EN7' (plus IMP / Age 1 Age.2 Age.3 Age-4 53 2013 U2, U3 flow X ENTvalue 0.51 0.0300 0.0350 0.2750 0.4500 54 2014 . U2, U3 flow X ENTvalue 0.51 0.0300 0.0350 - 0.2750 a4500 55 2015 U2, U3 flow X ENTvalue 0.51 0.0300 0.0350 0.2750 0.4500 56 2016 U3 flow X ESTvalue 0.51 a0300 0.0350 0.2750 0.4500 57 2017 U3 flow X ENT value 0.51 0.0300 0.0350 a2750 0.4500 58 2018 U3 flow X ENTvalue 0.51 0.0300 0.0350 0.2750 0.4500 59 2019 U3 flow X ENT valae 0.5\1 0.0300 0.0350 0.2750 0.4500 60 2020 U3 flow X ENTvalue 0.51 0.0300 0.0350 0.2750 a4500 61 2021 U3 flow X EhTvalue 0.51 0.0300 0.0350 0.2750 0.4500 62 2022 U3 flow X ESTvalue 0.51 0.0300 0.0350 0.2750 0.4500 63 2023 U3 flow X ENTvalue 0.51 0.0300 0.0350 0.2750 0.4500 64 2024 U3 flow X ENTvalue 0.51 0.0300 0.0350 a2750 0.4500 65 2025 U3 flow X Eh7value 0.51 0.0300 0.0350 0.2750 a4500 66 2026 0.0 0.50 0.0300 0.0350 0.2750 0.4500 67 2077 0.0 0.50 a0300 0.0350 0.2750- 0.4500 68 2028 0.0 0.50 0.0300 0.0350 0.2750 0.4500 69 2029 0.0 0.50 0.0300 0.0350 0.2750 0.4500 70 2030 0.0 0.50 0.0300 a0350 0.2750 0.4500 71 2031 0.0 0.50 0.0300 0.0350 0.2750 0.4500 72 2032 0.0 0.50 0.a100 0.0350 0.2750 0.4500 73 2033 0.0 0.50 0.0300 a0350 0.2750 0.4500 74 2034 0.0 0.50 0.0300 - 0.0350 0.2750 a4500 75 2035 0.0 0.50 0.0300 0.0350 0.2750 0.4500 76 2036 0.0 0.50 0.0300 0.0350 0.2750 0.4500 77 2037 0.0 0.50 a0300 0.0350 a2750 0.4500 78 2038 0.0 0.50 0.0300 0.al50 0.2750 0.4500 79 2039 0.0 0.50 0.0300 0.0350 0.2750 0.4500 80 2040 0.0 0.50 0.0300 a0350 0.2750 0 4500 81 2041 0.0 0.50 a0300 a0350 0.2750 0.4500 82 2042 0.0 0.50 0.0300 0.0350- 0.2750 0.4500 83 2043 0.0 0.50 0.0300 0.0350 02750 0.4500 54 2044 0.0 0.50 0.0300 0.0350 0.2750 0.4500 85 2045 0.0 0.50 0.0300 0.0350 0.2750 0.4500 86 2046 0.0 0.50 0.0300 0.0350 0.2750 0.4500 87 2047 0.0 0.50 0.0300 0.0350 0.2750 0.4500 88 2048 0.0 0.50 0.0300 0.0350 0.2750 0.4500 89 2049 0.0 0.50 0.0300 0.0350 0.2750 0.4500 90 2050 0.0 0.50 0.0300 0.0350 0.2750 0.4500 91 2051 0.0 0.50 0.0300 0.0350 0.2750 0.4500 92 2052 0.0 0.50 0.0300 0.0350 0.2750 0.4500 93 2053 0.0 0.50 0.0300 0.0350 0.2750 0.4500 94 2054 0.0 0.50 0.0300 0.u150 0.2750 0.4500 95 2055 0.0 0.50 0.0300 0.0350 0.2750 R4500
% 2056 0.0 0.50 0.0300 a0350 0.2750 a4500 97 2057 0.0 0.50 0.0300 0.0350 0.2750 0.4500 98 2058 0.0 0.50 0.0300 0.0350 0.2750 0.4500 99 2059 00 0.50 0.0300 0.0350 0.2750 0.4500 100 2060 0,0 0.50 0.0300 0.0350 0.2750 0.4500
- Ivr 1971-83 and 1994-2025 Eh7 values were randomly selected from projected rates detennined from mass. balance calculations for full threeenis operstian during 1984 93 (Table 39). Actual MNPS flow values were used for 1971-83 and randomly selected values from Table 5 were used for 1994 2025. ENT values for 1984 93 were estimates made under actual MNPS operating conditions as shown on Table 39.
b p values were obtained from the DEP (P. Howell and V. Crecco. CT DEP, Old Lyme, CT, pers. comm.). Impingement mortality was imple-unented es an equivalent instantaneous mortahty rate (0.01) held constant throughout the MNPS operational period (19712025). 216 M0nitoring Studies,1993
and remain unchanged throughout the rest of the ing from larval losses through entrainment at MNPS simulation time period. De unfished stock size used is related to the age structure of the spawning stock. initially in the simulation was 97,075 lbs (eq 2ivalent Fishing reduces biomass of the stock at a greater rate to approximately 66,950 female spawners). B ased on than it reduces the number of spawners because it I the age and size structure of female winter f.ounder tends to select for larger fish and, thus, reduces the ) used in the SPDM, this value was similar o the average weight of the spawners remaining in the deterministic estimate of Pup = 97,132 lbs given in population. However, the most important difference Table 33. The initial stock size represents the MSP between fishing (with an added component accounting for the unfished Niantic River female spawning stock. for impingement) and larval entrainment is that while However, the stochastic mean size of the exploited the former process removes fish from each year-class stock by 1970 (under the starting nominal fishing rate every year for as long as any fish remain, the latter of F = 0.40) was reduced to 48,271 lbs. The simulat- causes a reduction only once in the lifetime of each ed baseline responded as expected to the high rates of generation and, then, very early in the life history of a fishing through 1991 as the stock steadily declined to species. The relative effects of stock reductions due to 12.312 lbs in 1993 (the solid line in Figs. 38A and fishing and MNPS impact can be assessed by compar-39). This biomass is about half of the critical stock ing the unfished stock projection line to those for the - size (defined as a stock biomass equal to 25% of the fished stock with and without plant effects (Fig. 40). MSP) of 24,269 lbs, shown as the dashed line in he majority of biomass reductions are due to fishing. Figures 38A and B. This reference stock size will be Therefore, as fishing mortality is reduced throughout discussed in greater detail below. Even allowing for the 1990s and the baseline biomass increases rapidly, natural variation in the simulation, maximum repli- the absolute annual losses due to MNPS impact (i.e., cate values of stock sizes for several years were below the gap between the baseline and impacted losses in 25% of the MSP and minimum values were as small Fig. 39) become larger. However, these losses repre-as 8.4% of MSP. The simulation illustrated that the sent increasingly smaller fractions of a much larger baseline population could fall below the critical stock baseline. size at any time from 1985 through 1999. However, Stock sizes projected for each simulation scenario at if reductions in F work as planned the stock should seven selected points in time are given in Table 41; recover rapidly following its nadir in 1993. losses relative to the theoretical unfished stock for To determine the effect of MNPS on the Niantic each particular year are shown as percentages. Mini-River female spawning stock, the baseline time-series mum and maximum stock sizes representing the range may be compared to the impacted time-series, shown of stock sizes for the 100 Monte Carlo replicates in Figure 38B and as the dashed line (ENT + IMP) in generated for each year (shown on Fig. 38) are also Figure 39. The impacted series corresponds to projec- given. The theoretical unfished stock in each of the 7 tions of the same initial stock as the baseline, but years shown varied little and averaged about 102,000 with additional annual losses due to MNPS operation. Ibs for each year. Prior to MNPS operation in 1970, In this impacted population projection, the stock did the baseline and the impacted stocks were identical not respond to larval losses due to entrainment until (48,271 lbs) and made up about 47% of the unfished 1974 (the fourth year of Unit 1 operation), when stock. By 1990, winter flounder spawning stocks biomass began to decline below baseline levels (Fig. under full MNPS three-unit operation declined by 39). The lowest projected stock biomass (10,562 lbs) about 50% relative to 1970. However, this was was reached in 1993, whereas the greatest absolute mostly the result of increased fishing as the impacted decline relative to the baseline occurred in 2001 (a stock was only about 1,900 lbs less than the baseline, difference of 7,840 lbs), when the effects of reductions Smallest stock sizes were found in 1993 as a result of in F since 1994 were propagated through the spawn- high rates of exploitation during the early 1990s. The ing population. From this point on, biomass of the baseline and impacted stocks were only 12.3% and impacted stock generally paralleled that of the baseline 10.5%, respectively, of the unfished stock. By 2000, and began to approach it as MNPS units went offline. the baseline stock had responded more rapidly to. The impxted stock moved to within about 600 lbs of decreased fishing than the impacted stock. The gap the baseline in 2031,6 years after the end of Unit 3 between the two began to narrow in 2010 and 2020 operation in 2025, and became virtually identical to it and, as stated previously, were nearly indistinguish-by 2033. able by 2031, when the stock can be considered as The different nature of stock reductions caused fully recovered. directly by fishing and impingement and those result-WinterFlounder 217
80000- . J, w f700002-, . . .* " *
. . ,, e ,*
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- 2 .
Q m 50000. *,*. , C . W 40000- .
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1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 2060 YEAR t 80000- . _ 700002',. .* *
* . o
- j .. *. .,,.
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. / .*. f. . ._ ..
- . ~
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- u.
- 10000i **. B. lMPACTED 0, , , , , , , , , , , , , , , , , , , , ,
1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 2060 YEAR
^
Fig. 38. Stochastic variability associsted with the projected Niantic River female winter flounder stock expressed as biomass (lbs) for: A. The baseline stock with simulated sport and commercial fishing rates, but no effects from MNPS operation. and B. The impacted stock with both fishing effects and MNPS impact. 'Ihe solid lines are the geometric means 1 and 957. confidence interval (100 Monte Carlo replications) of each stock size trajectory and are equal to the baseline'and ) impacted stocks illustrated on Figure 39. The symbols above and below the line correspond to the largest and smallest r stocks among the 100 replicates generated for each year. The dashed line represents the critical stock size (here. 24.269 lbs), defined as when stock biomass has been reduced to 25% of the maximum sptwning potential (Howell et al.1992). 218 Monitoring Studies,1993 1
50000g ' ' '
' No impact ' '
45000i i sr i i .....
- 8. 40000i .,
a f ** . ,,,,8,,,/ ~J s i l i
$ i : I
< 350002 '
i i 1 ' O b # g 30000i i ,i / i i tr i i ! i
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- u. i e e i No i 1, 2 - , i 1, 2 , Recovery period 5000i ops i unit ops e 3-unit ops ' unit ops a (no units online) 0 ', ' ,:
, , , , , , , , l , , J , , , , , , ,
1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 2060 YEAR Fig. 39. Results of the SPDM simulation showing the combined effects of fishing and calculated larval entrainment rate and fish impingement rates (dashed line labeled ENT + IMP) on the biomass of the Niantic River female winter flounder spawn. ing stock. Entrainment rates changed annually according to the number of MNPS units in operation and fishing rates were also variable (see text and Table 40 for details). The solid line labeled "No impact"is the baseline with fishing effects only, All stock sizes are averages of 100 Mome Carlo replicates. ProbabillstIc assessment of MNPS commercial fishery. A stock that has been reduced to effects. The stochastic variability associated with less than 25% of the MSP is considered overfished and stock projections for combined fishing, impingement, its continued maintenance is questionable. Further-and larval entrainment illustrated in Figure 38B more, spawner abundance may decline to even lower formed the basis for probabilistic analyses. These levels. Alternatively, fishing rates that preserve 40% analyses took into account not only the mean stock of MSP allow for the preservation of the stock and biomass predicted for each year, but also the frequency maximize yield to the fisheries. This level may be distribution of 100 replicate predictions both smaller viewed as conservative because the simulations sug-and larger than the mean. To assess effects of MNPS gested that even under moderate exploitation in the operation, the probabilities that the Niantic River .1960s and 1970s, a number of simulated projection: female winter flounder spawning stock would fall were below 40% of MSP. below selected reference sizes were detennined. These Probabilities that the projected baseline and impac-reference sizes were percentages (25,30, and 40%) of ted stocks of Niantic River female spawner biomass the biomass of spawning females for the unfished would fall below 25,30, and 40% of MSP were stock (i.e., the MSP) and were suggested in the Atlan- determined (Table 42). In 1970, the stocks were tic States Marine Fisheries Commission managunent likely (p 2 0.87) larger than 40% of the MSP. How-plan for inshore stocks of winter flounder (Howell et ever, by 1980 both the baseline and impacted stocks al.1992). In castern LIS, values of F ranging from had increased probabilities (0.44,0.53) of falling 0.37 to 0.68 would be necessary to achieve maximum below 40% of MSP. In 1990, the baseline and im-yield, depending upon various combinations of length pacted stock sizes were almost certainly less than 40% (10, i1, or 12 inches) and trawl codend mesh (3.5, of MSP and likely (p 2 0.73,0.80) less than 30%'of - 4.5,5.0, or 5.5 inches) restrictions imposed on the. MSP. 'Ihe impacted stock also had a probability of WinterFlounder 219
i o 1 120000-Unfished stock E 100000- - V E
!?>
$ 80000-9 m
CC y 60000- F shed stock 3: No impact N 40000- , ..... ......."J' tu .
;;;! .. ,.- ENT + IMP
- lE .
@ 20000-
. 1 1 I & I B 3 I l l l l l l 5 4 l l 1 1 4 ]
1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 2060 YEAR Fig. 40. Illustration of the effects of fishing (solid line labeled "No impact") and MNPS operation under calculated larval entrainment and impingement rates (dashed line labeled "ENT + IMP") relative to the theoretical (SRR-based estimate) unfished stock expressed as female spawner biomass in Ibs. All stock sizes are averages of 100 Monte Carlo replicates. 0.45 of falling below 25% of MSP. At the lowest Conclusions point of both stock projections in 1993, all replicates were below 25% of MSP. Reductions in fishing rates The number of winter flounder spawning in the in the late 1990s allowed for a rapid increase in spawn- Niantic River further decreased in 1993 and adult ing biomass above this critical level to more optimal abundance indices were the lowest since sampling stock sizes by 2000. Spawning biomass was then began in 1976. The low level of abundance mirrored likely greater than 25% of MSP and the impacted regional trends reported by the National Marine Fisher-stock had a one in four chance of being greater than ies Service for recent years. Furthermore, the large 30% of MSP By 2010 and 2020, the stocks had high size of spawners and lack of smaller adults observed likelihood of being above 30% of MSP and the im- during the Niantic River surveys may be a forewarn-pacted stock had a better than even probability of ing of still more declines in spawner biomass during being greater than 40% of MSP. Note that these the next few years. The relatively small spawning probabilities may be viewed as conservative because stock produced the smallest densities of larvae yet due to the dynamics of the simulated stock, these found in Niantic River and Bay. Even with three-unit
- years happened to represent local minima in the stock operation, the number of larvae entmined at MNPS size time-series (see Fig. 38). For the stock to reach a was among the lowest in the 17-year series of annual more desirable size, which according to Howell et al. estimates. _ Juvenile winter flounder had somewhat (1992)is greater than 40% of MSP, fishing mortality better than average survival in 1993, but because woukt have to be further reduced. 'Ihe stock stabilized relatively few fish settled in the Niantic river, the at a biomass of about 43 to 44 thousand Ibs following 1993 year-class strength appears to be poor. This was j the shutdown of MNPS in 2025 and probabilities of in contrast to 1992 when, despite very low abundance >!
biomass being smaller than this reference size were of spawners, larval abundance was the highest in 18 about 30 to 40% annually. years and juvenile abundance indices indicated a 220 Monitoring Studies,1993
TABLE 41, Expected biomass in pounds of female winter flounder spawners at seven selected poinu in time during SPDM simuladons of the Niantic River population (see Figures 38 and 39). Expected mean stock sins are geometric means of 100 Monte Carlo replicates and the minimum and maximum stock sizes represent the range for the 100 replicates of each year. Type of populadan sirnulated 1970 1980 1990 1993 2000 2010 2020 Theoretical unfished stock
- s Mean 102,145 100,645 101,306 100,388 104,605 103,016 101,573 Abinuun 75,843 76,274 77.871 71,561 79,448 81,889 69,904 Maximum 141,890 135,589 135,781 137,863 146,M5 132,545 130,058 Baselineb Mean 48,271 40,352 26,413 12,312 40,571 43,988 43,160 Enimum 30,405 28,520 17,487 8,185 25,315 28,575 26,547 Maximum 75,404 62,991 43,190 23,005 63,357 65,211 63,667
% of the theoredcal unfished stock 47.3 % 40.1% 26.1 % 12.3 % 38.8 % 42.7 % 42.5 %
Impact (ENT + IMP)* Mean 48,271 39,094 24,531 10,562 32,890 38,767 39,836 Mmimum 30,405 27,552 16,W2 7,116 20,160 26,061 24,502 Maximum 75,405 61,171 40,040 19,598 52,666 56,634 57,448
% of the theoredcal unfished stock 47.3 % 38.8 % 241 % 10.5 % 31.4% 37.6 % 39.2 %
- No fishing or MNPS cffects.
- Fishing effects, but no MNPS impact.
- Combined effects of entrainment and impingement (ENT + IMP) at MNPS in addidun to fishing.
TABLE 42. Probabilities of Niantic her female spawmns sanck blamus falung below dree selected reference sins at seven selected points in time. Postulated reductions are selative to the maximum spawnma potential (MSP) of $17S75 lbs for the theoretical infished stock (F = 0). Probabihdes were based on 100 Mcmte Carlo replications of she simulations. Type of Reference population simulated stock sina 1970 1980 1990 1993 2000 2010 2020
~
Baschne* 25% of MSP 0.00 0.00 0.33 1.00 0.00 0.00 0.00 Impacted
- 25% of MSP 0.00 0.00 0.45 1.00 0.13 0.00- 0.00 Baseline 30% of MSP 0.00 0.01 0.73 1.00 0.09 0.01 0.02 Impacted 30% of MSP 0.00 0.01 0.80 1.00 0.24 0.03 0.02 Baseline 40% of MSP 0.13 0.44 0.99 1.00 0.41 0.21 0.26 Irnpacted 40% of MSP 0.13 0.53 0.99 1.00 0.78 0.52 0.44
- Corresponds to reference stock sius given in flowell et at (1992) of 25%,30%, and 40% of the MSP (24,269,29,123, and 38,830 lbs, respecdvely).
- Fishing effects, tot no MNPS impact
- Combined effects of entrainment and impingement (ENT + IMP) at KNPS in addition to fishing.
WinterFlounder 221
i relatively stmng year-class. A number of environmen- Arai, M.N., and D.E. Hay. 1982. Predation by 1 tal and biological factors interact to determine reproduc- medusae on Pacific herring (Clupea harengus) l tive success within a particular year. The low abun- larvae. Can J. Fish. Aqual Sci. 39:1537-1540. dance of adult spawners in 1993 combined with low Arnason, A.N., and K.H. Mills.1981. Bias and loss larval production will retard the recovery of the of precision due to tag loss in Jolly-Seber esti. Niande River winter flounder stock. However, newly mates for mark recapture experiments. Can. J. implemented fishing regulations may protect the Fish. Aquat. Sci. 38:10771095. I relatively strong 1992 year-class, helping increase the Bagge, O., and E. Nielsen. 1988. The change in numbers of spawning fish in subsequent years, abundance and growth of plaice and dab in Subdivi-A long-term assessment using the SPDM indicated sion 22,1965-1985. ICES Bal/No. 27. (Not that fishing alone reduced Niantic River spawner seen, cited by Pihl and van der Veer 1992). biomass from somewhat more than 100,000 lbs for Bailey, K.M., and R.S. Batty. 1984. Laboratory the theoretical unfished stock to about half that study of predation by Aureliaaurelia on larvae of amount by the 1960s and 1970s. Large increases in cod, flounder, plaice and herring: development and fishing mortality since then reduced baseline (fishing vulnerability to capture. Mar. Biol. 83:287-291. effects only) stock biomass rather rapidly to about Bannisterc R.C.A., D. Harding, and SJ. Lockwood. 12.000 lbs by 1993. Adding the effects of MNPS 1974. Larval mortality and subsequent year-class operation (primarily larval entramment) further reduced strength in the plaice (Pleuronectesplatessa I .). stock size by an addidonal 1,500 lbs. These stock Pages 21-38 in J.H.S. Blaxter, ed. The early life sizes are considerably below the critical size (about history of fish. Springer-Verlag, New York. 24,000 lbs), defined by the Atlantic States Marine Begon, M.1979. Investigating animal abundance: Fisheries Commission as 25% of the maximum capture-recapture for biologists. University Park spawning potential (i.e., spawner biomass in the Press, Baltimore. 97 pp. absence of fishing). However, the simulation of Berghahn,R.1986. Determining abundance, distribu-substantial reductions in fishing mortality expected to tion, and mortality of 0-group plaice (Pleuronectes occur in the near future as a result of new regulations platessa L.) in the Wadden Sea. J. Appl. Ichthyo1. showed that the stock could recover quickly. By 2: 11-22. 2000, the baseline and MNPS-impacted stocks had Berghahn, R.1987. Effects of tidal migration on high probability of being larger than 25% of MSP and growth of 0-group plaice (Pleuronectesplatessa L.) by 2010 of being greater than 30% of MSP As stock in the North Frisian Wadden Sea. Meeresforsch. abundance increased, the effect of MNPS became 31:209-226. (Not seen, cited by Karakiri et al. larger in terms of absolute losses of stock biomass. 1989). However, the two biomass time-series became identi- Bergman, MJ.N., H.W. van der Veer, and JJ. cal within a few years after the cessation of MNPS Zijlstra.1988. Plaice nurseries: effects on recruit-operation in 2025 and the stock could be considered as ment. J. Fish Biol. 33 (Suppl. A): 210-218. fully recovered. This scenario, however, will require Bishop, J.A., and P.M. Sheppard. 1973. An evalua-that the planned changes in fishing regulations be tion of two capture-recapture models using the implemented as scheduled and that they achieve the technique of computer simulation. Pages 235-253 expected reductions in fishing mortality. In M.S. Bartlett and R.W. Hioms, eds. The mathematical theory of the dynamics of biological References Cited populations. Academic Press, London. > Boudreau, P.R., and L.M. Dickie. 1989. Biological Al-Hossaini, M., Q. Liu, and TJ. Pitcher. 1989. model of production based on physiological and Otolith microstructure indicating growth and ecological scaling of body size. Can. J. Fish, mortality among plaice,Pleuronectesplatessa L., Aquat. Sci. 46:614-623. post-larval sub-cohorts. J. Fish Biol. 35 (Suppl. Buckley, LJ.1980. Changes in ribonucleic acid, A):81-90. deoxyribonucleic acid, and protein content during : Anderson, J.T.1988. A review of size dependent ontogenesis in winter flounder, Pseudopleuronectes survival during pre-recruit stages of fishes in americanus, and effect of starvation. Fish. Bull., relation to recruitment. J. Northw. Atl. Fish. Sci. U.S. 77:703-708. 8:55-66. 222 Monitoring Studies,1993
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