ML20246B717
| ML20246B717 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 11/30/1988 |
| From: | NORMANDEAU ASSOCIATES, INC. |
| To: | |
| Shared Package | |
| ML20246B660 | List: |
| References | |
| XIX-II, NUDOCS 8905090149 | |
| Download: ML20246B717 (408) | |
Text
"
I. m- ,
-]-
i s
1 ATTACHMENT 1 1 I
E i
[-
l 4
SEABR00K' ENVIRONMENTAL STUDIES, 1987.
A CHARACTERIZATION OF BASELINE CONDITIONS
~
! -IN THE HAMPTON-SEABROOK AREA, 1975-1987.
A PREOPERATIONAL STUDY FOR SEABROOK STATION!
s TECHNICAL REPORT XIX-II Prepared for ;
l' NEW HAMPSHIRE YANKEE DIVISION PUBLIC SERVICE COMPANY OF NEW HAMPSHIRE P.O. Box 700 Seabrook Station i Seabrook,'New Hampshire 1
Prepared by !
l I
NORMANDEAU' ASSOCIATES INC.
25 Nashua Road 'l Bedford, New Hampshire 03102.
R-3131 November.1988. > <
R
.g
)
TABLE OF CONTENTS
(
i PAGE l
1.0 EXECUTIVE
SUMMARY
. . . . . . . . . . . . . . . . . . . . . . 1
)
1.1 INTRODUCTION
. . . . . . . . . . . . . . . . . . . . . . 1 1.2 INTAKE MONITORING . . . . . . . . . . . . . . . . . . 2 1.3 DISCHARGE MONITORING. . . . . . . . . . . . . . . . . . 4 1.3.1 Discharge Plume Monitoring . . . . . . . . . . . 4
/ 1.3.2 Benthic Monitoring . . . . . . . . . . . . . . 5 1.3.3 Estuarine Monitoring . . . . . . . . . . . . . 6 2.0 DISCUSSION . . . . . . . . . . . . . . . . . . . . . . 9
2.1 INTRODUCTION
. . . . . . . . . . . . . . . . . . . . . . 9 2.1.1 General Perspective. . . . . . . . . . . . . . . 9 2.1.2 Sources of Baseline Variability. . . . . . . . 9 2.2 INTAKE AREA MONITORING. . . . . . . . . . . . . . 15 2.2.1 Plankton . . . . . . . . . . . . . . . . . . 15 2.2.1.1 Community Structure . . . . . . . . . 15 2.2.1.2 Selected Species. . . . . . . . . . . 20 2.2.1.3 Spatial Variability . . . . . . . . . 25 2.2.2 Pelagic Fish . . . . . . . . . . . . . . . . . 25 2.2.2.1 Temporal. . . . . . . . . . . . . . . 25 2.2.2.2 Spatial . . . . . . . . . . . . . . . 30 2.3 DISCHARGE AREA MONITORING . . . . . . . . . . . . . . . 33 2.3.1 Plume Studies. . . . . . . . . . . . . . . . . . 33 2.3.1.1 Discharge Plume Zone. . . . . . . . . . 33 2.3.1.2 Intertidal / Shallow Subtidal Zone. . . . 40 2.3.1.3 Estuarine Zone. . . . . . . . . . . 47 2.3.2 Benthic Monitoring . . . . . . . . . . . . . . . 56 ;
2.3.2.1 Macroalgae and Macrofauna . . . . . . . 56 2.3.2.2 Demersal Fish . . . . . . . . . . . 61 2.3.2.3 Epibenthic Crustacea. . . . . . . . . . 66 111
I PAGE 'k
.4 3.0 RESULTS. . . . . . . . . . . . . . . . . . . . . . . . . . . 69 4 3.'l~ PLANKTON AND WATER QUALITY PARAMETIRS . . . . . . . . . 69 3.1.1 Water-Quality Parameters-Seasonal Cycles and f Trends . . . . . . . . . . . . . . . .. . . . . 69 l 3.1.2 Bivalve Veliger Larvae . . . . . . . . . .. . . 80 i ik 3.1.2.1 Community.. . . . . . . . . . . . . . . 80 3.1.2.'2 Selected Species. . . . . . . . . . . 86 3.1.3 Macrozooplankton . . . . . . . . . . . . . . . . '88 3.1.3.1 Community Structure . . . . . . . . . . . 88 1 3.1.3.2 Selected Species. . . . . . . . . . . . 98 3.2 FINFISH , . . . . . . . . . . . . . . . . . . . .. . . 107 3.2.1 Ichthyoplankton. . . . . . . . . . . .. . . . . 107 3.2.1.1 Total Community . . . . .. . . . . . . . 107 3.2.1.2 Selected Species. . . . . . . . . . . . 128 3.2.2 Adult Finfish. . . . . . . . . . . . .. . . . . 143 3.2.2.1 Total Community . . . . . . .. . . . . 143 3.2.2.2 Selected Species. . . . .. . . . . . . 161 3.2.3 Finfish Appendix Tables. . . . . . . . . . . . . 178-3.3 BENT 110S . . . . . . . . . . . . . . . . . . . . . . . 185 3.3.1 Estuarine Benthos. . . . . . . . . . . . . . . . 185 l 1
3.3.1.1 Physical Environment. . . . . . . . . . 185l 3.3.1.2 Macrofauna. . . . ... . . . . . . . . . 193 3.3.2 Marine Macroalgae. . . . . . . . . . . . . . . . 205 3.3.2.1 Macroalgal Community. . . . . . . . . . 205 3.3.2.2 Selected Species. . . . . . . . . . . . 223 i iv
PAGE 3.3.3 Marine Macrofauna. . . . . . . . . . . . . . . . 229 3.3.3.1 Algae Covered Ledge Community . . . . . 229 3.3.3.2 Intertidal Bare Rock, Fuccid Ledge, and Chondrus Communities. . . . . . . . 240 3.3.3.3 Subtidal Fouling Community. . . . . . . 244 3.3.3.4 Nodiolus modlolus Community . . . . . . 246 3.3.4 Surface Fouling Panels . . . . . . . . . . . . 248 3.3.4.1 Seasonal Settlement Patterns. . . . . . 248 3.3.4.2 Patterns of Community Development . . . 255 3.3.5 Selected Benthic Species . . . . . . . . . . . . 261 3.3.5.1 Mytilidae . . . . . . . . . . . . . . 261 3.3.5.2 Nucella lapillus. . . . . . . . . . . . 267 3.3.5.3 Aster 11dae. . . . . . . . . . . . . . . 267 3.3.5.4 Pontogenela inermis . . . . . . . . . 269 3.3.5.5 Jassa falcata . . . . . . . . . . . . . 270 3.3.5.6 Ampithoe rubricata. . . . . . . . . . . 271 3.3.5.7 Strongylocentrotus droobachiensis . . . 272 3.3.6 Epibenthic Crustacea . . . . . . . . . . . . . . 274 3.3.6.1 American Lobsters (Fomarus americanus). 274 3.3.6.2 Rock Crab (Cancer 1rroratus) and Jonah Crab (Cancer borealls). . . . . . 286 3.3.7 #ya arenarla (Soft-shell Clam) . . . . . . . . . 292 3.3.7.1 Larvae. . . . . . . . . . . . . . . . 292 3.3.7.2 Reproductive Patterns . . . . . . . . . 294 3.3.7.3 Hampton Harbor and Regional Popula-tion Studies. . . . . . . . . . . . . . 294 3.3.8 Benthos Appendix Tables. . . . . . . . . . . . . 317 4.0 METHODS. . . . . . . . . . . . . . . . . . . . . . . . . . . 347 4.1 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . 347 4.2 COMMUNITY STRUCTURE . . . . . . . . . . . . . . . . . 356 4.3 SELECTED SPECIES / PARAMETERS . . . . . . . . . . . . . . 361 5.0 LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . 369 v
(
LIST OF FIGURES f PAGE i
2.1-1. Schematic of sources and levels of variability in (
Seabrook Environmental Studies . . . . . . . . . . . . 11 2.2-1. Historical dates of occurrence and mean abundance j (excluding rare taxa) for seasonal groups formed by 3 numericalclassificationofmicrozooplangton(No.fm, 1976-1984), macrozoopgankton(No./1000m, 1978-1984), f fisheggs(go./1000m, 1976-1984), and fish larvae \
(No./1000 m , 1976-1984) collections . . . . . . . . . 16 1
2.2-2. Percent composition, seasonal vs. annual variability I (standard deviation) of log (x+1) abundance, and months of peak abundance for selected species of
(
phytoplankton (thogsands.of cells / liter) and micro-zooplankton (No./m ), 1978-1987. . . . . . . . . . . 21 f 2.2-3. Percent composition, seasonal vs. annual variability (standard deviation) of log (x+1) abundance, and m2 nths ofpeakabundanceforlobsterlarvae(No.f1000m)and selected species of bivgive larvae (No./m ) and macro-zooplankton (No./1000 m ). . . . . . . . . . . . . . 22 2.2-4. Percent composition, seasonal vs. annual variability (standard dgvlation) of log (x+1) abundance (No./1000 m ), and months of peak abundance for selected species of fish larvae, 1975-1987 . . . . . . 23 2.2-5. Seasonal and annual changes in composition and abundance of the pelagic fish community, based on catch per unit effort at gill not stations G1, G2, and G3 combined, 1976-1987 . . . . . . . . . . . . 27 f
2.2-6. Percent composition, seasonal vs. annual variability (standard deviation) of log (x+1) abundance (catch per unit effort), and months of peak abundance for selected species of fish, 1976-1987. . , . . . . . 29 2.3-1. Seasonal vs. annual variability (standard deviation) and months of peak values for temperature ('C),
salinity (ppt), dissolved oxygen (mg/1), and nutrients (pg/1) . . . . . . . . . . . . . . . . . . . 34 2.3-2. Monthly mean surface and bottom temperature('C),
surface salinity (ppt), and surface dissolved oxygen (mg/1) at station P2 for each year and over all years (1978-1986, except temperature, 1978-1984 and August 1986-December 1987) . . . . . . . . . . . . . . . 35
(
vi .
i
___._________________a
i
)
PAGE 2.3-3. Annual settlement periods, abundance and survival ,
of major taxa based on examination of sequentially- !
7 exposed panels at nearfield Stations 4 and 19. . . . . . 39
~
2.3-4. Depth and abundance characterizations of species assem- ,
blages identified by discriminant analysis of August collections of algae (g/g of dominant taxa) and marine benthos (thousands per m of dominant taxa) during 1978-1987. . . . . . . . . . . . . . . . . . . . . 41 2.3-5. Percent composition (based on biomass) by depth strata for dominant macroalgae species at marine benthic stations in August, 1978-1987. . . . . . . . . . . . 42 2.3-6. Percent composition and nearfield (.ita. 1MLW & 17) vs. farfield (Sta. 5MLW & 35) annus1 variability (standard deviation) of log (x+1) abundance for selected intertidal and shallow subtidal species of algae and benthos . . . . . . . . . . . . . . . . . 46 i
2.3-7. Mean monthly seawater surface temperature and salinity !
with 95% confidence limits taken at low tide in 1 Brown's River (Sta. 3) in 1987 and over the entire l study period (May 1979 - December 1987). . . . . . . . 48
]
2 2.3-8. Annual geometric mean density (No./m ) and mean number of taxa per station of estuarine benthos, and annual mean salinity, at Brown's River and Hampton Harbor . . 50 2.3-9. Seasonal and annual changes in composition and abundance of the estuarine fish community, based on catch per unit effort at beach seine Stations S1, S2 and S3-combined, 1976-1984 and 1987 . . . . . . . . 51
\
2.3-10. Percent composition by station for abundant species of fish collected in beach seines, all years combined, 1976-1987. . . . . . . . . . . . . . . . . . . . . 53 2.3-11. Annual geans and 95% confidence limits of densities (No./ft ) of Nya arenaria young-of-the-year and spat in Hampton-Seabrook on Flat 1. . . . . . . . . . . . . 55 2.3-12. Number of adult clam licenses issued and the adult clam standing crop (bushels), Hampton-Seabrook Harbor, 1971-1987. . . . . . . . . . . . . . . . . . 57 2.3-13 Percent composition and nearfield (Sta. 19) vs.
farfield (Sta. 31) annual variability (standard deviation) of log (x+1) abundance for selected mid-depth benthic species, 1978-1987 . . . . . . . . . . 60 vii
PAGE 2.3-14. Seasonal and annual changes in composition and abundance of the demersal fish community, based on catch per unit effort at otter trawl stations T1, T2 and T3 combined, 1976-1987. . . . . . . . . . . . . 62 2.3-15. Percent composition by station for abundant species of fish collected in otter trawls, all years combined, 1976-1987. . . . . . . . . . . . . . . . . . . . . . 64 2.3-16. Seasonal vs. annual variability (standard deviation) and months of peak abundance (catch per 15-trap effort) for adult lobsters and crabs . . . . . . . . . 67 2.3-17. Size-class distribution (carapace length) of Eomarus americanus at the discharge site, 1975-1987. . . . . . 68 3.1.1-1. Monthly mean temperature at Station P2, all years' mean and 95% confidence interval for 1978-1987 and monthly mean for 1987 for surface and bottom . . . . . 70 3.1.1-2. Differences between surface and bottom temperatures taken semi-monthly at Station P2, 1978-1987. . . . . . 71 3.1.1-3. Surface salinity and bottom salinity at nearfield Station P2, monthly means and 95% confidence intervalo over all years, 1978-1987, and monthly means for 1987 . . . . . . . . . . . . . . . . . . . 73 3.1.1-4. Dissolved oxygen at nearfield Station P2, monthly means and 95% confidence intervals over all years, 1978-1987, and monthly means for 1987 for surface and bottom . . . . . . . . . . . . . . . . . . . . . . 74 3.1.1-5. Orthophosphate and total phosphorus at nearfield Station P2, monthly means and 95% confidence inter- .
vals over all years from 1976-1984 and 1986-1987, and monthly means for 1987 . . . . . . . . . . . . . . 75 3.1.1-6. Nitrite-nitrogen and nitrate-nitrogen concentrations at nearfield Station P2, monthly means and 95% con-fidence intervals over all years from 1978-1984 and 1966-1987, and monthly means for 1987. . . . . . . . . 76 3.1.1-7. Ammonia concentrations at nearfield Station P2, monthly means and 95% confidence intervals over all years from 1978-1984 and 1986-1987, and monthly means for 1987 . . . . . . . . . . . . . . . . 77 (
i vill
{
l' l
PAGE l 3.1.2-1. Number of years present and number of years in high I
abundance (> 50% of seasonal peak abundar.ce) of bivalve veliger larvae by week at Station P2, 1978-1987. Years enumerated: a. 1976-1987; l b. 1978-1984, 1986-1987; c. 1979-1984, 1986-1987 . . . 82 l
3.1.2-2. Weekly mean abundance and 95% confidence intervals for Nytilus edu11s larvae at nearf.ield Station P2 over all years, 1978-1987. . . . . . . . . . . . . . . 87 3.1.3-1. Log (x+1) abundance por 1000 cubic meters for Calanus finmarchicus copepodites and adults; monthly mean and 95% confidence interval over all years 1978-1984, 1986-1987 and monthly means for 1987 . . . . . . . . . 100 3.1.3-2. Log (x+1) abundance per 1000 cubic meters for Carcinus maenas larvae and Crangon septemspinosa zoeae and post-larvae; monthly mean and 95% confidence interval over all years 1978-1984, 1986-1987 and monthly means for 1987 . . . . . . . . .. . . . . . . . . . . . . . . 103 3.1.3-3. Log (x+1) abundance per 1000 cubic meters for Neomysis americana; monthly mean and 95% confidence interval over all years 1978-1984, 1986-1987 and monthly reans for 1987 and mean parcent composition of Neomysis americana lifestages over all years 1978-1984, 1986-1987 at nearfield Station P2. . . . . . . . 105 3.2.1-1. Mean and 95% confidence limits over all years and 1987 values, by month for log (x+1) transformed 3
abundance (No./1000 m ) for American sand lance and winter flounder larvae at Stations P2 and P3, July 1975 through December 1987 . . . . . . . . . . . . . . 132 3.2.1-2. Mean and 95% confidence limits over all years and 1987 values, by month'3f r 1 g (x+1) transformed abundances (No./1000 m ) for yellowtail flounder and Atlantic cod larvac Stations P2 and P3, July 1975 through December 1987. .. . . . . . . . . . . . . . . 136 3.2.1-3. Mean and 95% confidence limits over all years and 1987 values, by month'3f r 1 g (x+1) transformed abundances (No./1000 m ) for Atlantic mackerel and cunner larvae at Stations P2 and P3, July 1975 through Dect nber 1987. .. . . . . . . . . . . 138 IX
PAGE 3.2.1-4. Mean and 95% confidence limits over all years and 1987 values, by month,3f r 1 g (x+1) transformed abundances (No./1000 m ) for hake and Atlantic herring larvae at Stations P2 and P3, July 1975 through December 1987. . . . . . . . . . . . . . . . . 140 3.2.1-5. Mean and 95% confidence limits over all years and 1987 values, by month,3for log (x+1) transformed abundances (No./1000 m ) for pollock larvae at Stations P2 and P3, July 1975 through December 1987. . 142 3.2.2-1. Catch per unit effort (mean number per 10 minute tow) of all species collected in otter trawls by year, station and all stations combined, 1976-J987 . . 144 3.2.2-2. Catch per unit effort (number per 24-hour set of one net, surface or bottom) of all species combined in gill nets by year, station and all stations combined, 1976-1987 . . . . . . . . . . . . . 150 3.2.2-3. Catch per unit effort (mean number per seine haul) of all species collected in beach seines by year, station and all stations combined, 1976-1984 and 1987 . . . . . . . . . . . . . . . . . . . . . ... . 157 3.2.2-4. Mean and 95% confidence limits over all years and 1987 values, by month, for log (x+1) transformed catch por unit effort (one 24-hr. set) for Atlantic horring and pollock at combined gill net stations G1, G2 and G3 from 1976-1987 . . . . . . . . . . . . . . . 163 3.2.2-5. Mean and 95% confidence limits over all years, and 1987 values, by month, for log (x+1) transformed catch per unit effort (one 24-hr. set for gill nets, one 10-min. tow for otter trawl) for Atlantic mackerel at combined gill net Stations G1, G2 and G3 and Atlantic cod at otter trawl Station 72, 1976-1987. . . . . . . . . . . . . . . . . . . . . . . 167 i
3.2.2-6. Mean and 95% confidence limits over all years, and 1987 values, by month, for log (x+1) transformed catch per unit effort (one 10-min, tow) for hakes and yellowtail flounder at otter trawl Station T2, 1976-1987. . . . . . . . . . . , . . . . . . . . . . . 169 x
L 1 l
! PAGE
(
3.2.2-7. !!can and 95% confidence limits over all years, and 1987 values, by month, for log (x+1) transformed-catch'per unit effort (one 10-min. tow for otter trawls and one haul for beach seines) for winter i flounder at otter trawl Station T2 1976-1987 and .j combined beach seine Stations-S1, S2 and S3 1976- )
1984 and 1987. . . . . . . . . . . . . . . . . . . . . 172 3.2.2-8. Mean and 95% confidence limits over all years and' ,
f 1987 values,.by month, for log (x+1) transfored catch per unit effort (one 10-min.' tow for otter j trawl and one haul for. beach seines).for rainbow l smelt at otter trawl Station T2 1976-1987 and combined beach seine Stations S1,'S2, and S3 from 1976-1984 and 1987 . . . . . . . . . . . . . . . . . . . 175 !
f 3.2.2-9. Mean and 95% confidence limits over all years, and 1987 values, by month, for log (x+1) transformed catch per unit effort (one haul for beach reines) for Atlantic silverside at combined beach seine Stations S1, S2 and S3 1976-1984 and 1987. . . . . . 177 3.3.1-1. Mean monthly seawater surface temperature and salinity with 95% confidence limits talan at low tide in Brown's River over the entire study period (May 1979 -
December 1987) and in 1987 . . . . . . . . . . . . . . 186 3.3.1-2. Mean annual salinity at low tide in Brown's River and in Hampton Harbor, and total annual precipita-tion from 1980 through 1987. . . . . . . . . . . . . . 190 3.3.1-3. Monthly outfall from the Seabrook. Settling Basin from 1978-1987 in millions of gallons per day (GPD). . 191 3.3.1-4. Yearly mean and 95% confidence limits for the log (x+1) density of macrofauna and number of taxa collected at subtidal estuarine stations sampled three times per year from 1978 through 1987 (excluding 1985) . . . 196 3.3.1-5. Yearly mean and 95% confidence limits for the log (x+1) density of macrofauna and number of taxa collected at intertidal estuarine stations sampled three times per year'from 1978 through 1987 (excluding 1985) . . . 197 3.3.1-6. Yearly mean and 95% confidence limits for the log (x+1) density of Herels diversicolor and Hya arenaria collected at subtidal estuarine stations three times per year from 1978 through 1987 (excluding 1985) . . . 200-
)
.i x1 w_-__-_______- ___ . - _ _
PAGE 3.3.1-7. Yearly mean and 95% confidence limits for the log (x+1) density of Nerels diversicolor and Hya arenarla collected at intertidal stations three times per year from 1978 through 1987 (excluding 1985). . . . . . . . 202 3.3.2-1. Number ot' macroalgae species in general collections at each marine benthic station for 1978-1984 (median and range) and 1985-1987 (number collected each year). . . . . . . . . . . . . . . . . . . . . . . . . 206 3.3.2-2. A. Number of taxa and B. mean biomass at intertidal and subtidal benthic stations in August. . . . . . . . 208 3.3.2-3. Mean biomass (g/m 2 ) and 95% confidence limits for macroalgae collected in August at selected near-field benthic stations . . . . . . . . . . . . . . . . 209 3.3.2-4. Relative abundance (% biomass) of dominant macroalgae at marine benthic stations (by station-depth group) in August 1978-1987 . . . . . . . . . . . . . . . . . . . 211 3.3.2-5. Occurrence and peak biomass of the common and abundant macroalgae species over the range of benthic stations sampled in August 1978-1984 . . . . . 215 3.3.2-6. A. Mean and 95% confidence interval of log No./100 m of kelps (1978-1987; Station 35: 1982-1987) and B. Percent frequencies and 95% confidence interval of dominant understory algae (1981-1987; Station 35:
1982-1987) in the shallow and mid-depth subtidal zone. 219 3.3.2-7. Mean percent frequency and standard deviation of fucold algae at two fixed transect sites in the mean sea level zone (1983-1987) . . . . . . . . . . . . . . 222 3.3.2-8. Mean biomass (g/m 2
) and 95% confidence limits of Chondrus crispus at selected stations in May, August and November, Stations 17, 35: 1978-1987, Stations 35 and 1MLW: 1982-1987). . . . . . . . . . . . . . . . . 227 l
3.3.3-1. Number of taxa and overall abundance (No./ square meter) over all years (1978-1987, Stations 1MLW, 17, 19, 31; 1982-1987, SMLW, 35; 1979-1984,1986-1987, 34; 1978-1984, 1986-1987, 13, 4, 16) at intertidal and i subtidal benthic stations. . .. . . . . . . . . . 230 l
3.3.3-2. Annual mean abundance (No./ square meter) and 95%
confidence limits for macrofauna collected in August for nearfield Stations 1MLW (intertidal) and 17 (shallow subtidal) . . . . . .. . . . . . . . . . . 232 i xil q
i PAGE 3.3.3-3. Annual number of taxa collected in August at intertidal l
Stations 1MLW and SMLW and shallow subtidal Stations 17 and 35. . . . . . . . . . . . . . . . . . . . . . . 233 l 3.3.3-4. Annual number of taxa collected in August at Stations
} 16, 19, and 31 (mid-depth); and Stations 4, 13, and 34 (deep) . . . . . . . . . . . . . . . . . . . . . . . . 234 3.3.3-5. Annual mean abundance (No./ square meter) and 95%
l confidence limits for macrofauna collected in August L for nearfield Stations 19 and 16 (mid-depth) and 4 (deep) . . . . . . . . . . . . . . . . . . . . . . 235 3.3.4-1. Faunal richness (number of different taxa over two replicates) in 1987 compared to mean species richness and il 95 confidence limits from 1978-1987 on short term panels. . . . . . . . . . . . . . . . . . . . 249 3.3.4-2. Species abundance (log x+1) in 1987 compared to mean
! species abundance (log x+1; 195% confidence limits) from 1978-1987 for non-colonial fauna on short-term panels . . . . . . . . . . . . . . . . . . . . . . . . 251 3.3.4-3. Annual settlement periods, abundance and survival of major taxa based on examination of sequentially-exposed panels at nearfield Stations 4 and 19. . . . . 256 3.3.6-1. Weekly mean log (x+1) abundance (No./1000 m2 ) og lobster larvae at Station P2, 1978-1987, all year's mean and 95% confidence interval and 1987. (No data collected January 1985-June 1986). . . . . . . . . . . 276 3.3.6-2. Comparisons of legal and sub-legal sized catch of Eomarus americanus at the discharge site, 1975-1987. . 284 3.3.6-3. Size-class distribution (carapace length) of Nomarus americanus at the discharge site, 1975-1987. . . . . . 285 3.3.6-4. Summary of female lobster catch data at the discharge site, 1974-1987. . . . . . . . . . . . . . . . . . 287 3.3.6-5. Monthly mean log (x+1) abundance (No./1000 m3 ) of Cancer spp. larvae at Station P2, 1978-1987. (No data collected January 1985-June 1986). . . . . . . . . . . 288 3.3.7-1. Weekly log (x+1) abundance per cubic meter of tfya arenarla larvae at Station P2, 1978-1987, all years' mean and 95% confidence interval and weekly mean for 1987 . . . . . . . . . . . . . . . . . . . . 293 xiit i
PAGE 3.3.7-2. Log (x+1) abundance per cubic meter of Nya arenaria veligers at neartic1d Station P2, farfield Station P7 and llampton lierbor Station P1, 1982-1987 . . . . . . . 295 3.3.7-3. Abundance (No./ft ) of 1-mm size classes of Nya arenaria in Hampton-Seabrook Harbor during early fall, 1974-1987. . . . . . . . . . . . . . . . . . . . . . 298 3.3.7-4. Annual mean density (number per square foot) and 95%
confidence limits of young-of-the-year Nya arenarla (1-5 mm) at 1(ampton-Seabrook Harbor, 1974-1987 . . . . 300 3.3.7-5. Mean and 95% confidence limits of Nya arenarla spat (shell length 512 nm) densities (No./ft') at two northern New England estuaries, 1976 through 1984 and 1986 through 1987. . . . . . . . . . . . . . . . . 301 3.3.7-6. Means and 95% confidence limits of spat, juvenile and adult log (x+1) densities at Flat 1, Hampton-Seabrook Harbor, 1974 through 1987. . . . . . . . . . . . . . . 303 3.3.7-7. Means and 95% confidence limits of' spat, juvenile and adult log (x+1) densities at Flat 2, Hampton-Seabrook Harbor, 1974 through 1987. . . . . . . . . . . . . . . 304 3.3.7-8. Means and 95% confidence limite of spat, juvenile and adult log (x+1) densities at Flat 4, Hampton-Seabrook Harbor, 1974 through 1987. . . . . . . . . . . . . . . . 305 3.3.7-9. Fall mean catch per unit effort for green crabs (Carcinus maenas) in llampton-Seabrook Harbor and its relationship to minimum winter temperature, 1978-1987. 308 3.3.7-10. Number of adult clam licenses issued and the adult clam standing crop (bushels), Hampton-Seabrook Harbor, 1971-1987. . . . . . . . . . . . . . . . . . . . . . . 312 4.1-1. Plankton sampling stations . . . . . . . . . . . . . . 348 4.1-2. Finfish sampling stations. . . . . . . . . . . . . . . 349 4.1-3. Benthic marine algae and macrofauna sempling stations. 351 4.1-4. Hampton-Seabrook Estuary temperature / salinity, soft-shell clam (#ya arenaria), benthic transects and green crab (Carcinus maenas) sampling stations. . . . . . . . 352
(
4 xiv
_ - _ - - _ _ - _ - _ _ . . _ - _ i
I
- PAGE
! 4.1-5. Locations of lobster and rock crab trapping areas. . . 354 I
4.1-6. Sampling sites for #ay arenarla spat . . . . . . . . . 355 L-1 I
e d
XV
_ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ ___a
LIST OF TABLES PAGE 2.1-1. Summary of Biological Communities and Species Monitored for each Potential Impact Type . . . . . . . . 13 2.2-1. Comparison of Densities of Top-Ranked Fish Egg, Fish Larvae, and Bivalve Larvae Taxa Collected Offshore at Station P2 and in Entrainment Samples at Seabrook Station from July 1986 through June 1987 . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.2-2. Summary of Nearfield/Farfield (P2 vs. P7) Spatial Differences in Plankton Communities and Selected Species. . . . . . . . . . . . . . . . . . . . . . . . 26 P.2-3. Catch Per Unit Effort by Depth for the Dominant Gill Net Species Over All Stations and Dates When Surface, Mid-Depth and Bottom Nets Were Sampled, 1980 Through 1987 . . . . . . . . . . . . . . . . . . . . . . 32 2.3-1. Selected Benthic Species and Rationale for Selection . . 43 2.3-2. Summary of Similarities in Abundance, Biomass, Frequency, or Length Among Years and Between Stations for Selected Macrofaunal and Macroalgal Species at Intertidal and Shallow Subtidal Depths . . . . . . . . . 45 2.3 3. Summary of Similarities in Abundance or Length Among Years and Between Stations for Selected Species in the Mid-Depth Zone . . . . . . . . . . . . . . . . . . . 59 3.1.r-1. Annual Means and Coefficients of Variation of Water Quality Parameters Measured During Plankton Cruises at nearfield Station P2, 1978-1984 and 1986-1987 . . . . 79 3.1.2 1. Overall Percent Composition of Bivalvia Veliger Larvae in 76-pm Net Tows at Stations P1, P2 and P7 from Mid-April Through October, 1982-1987 . . . . . . . . . . 81 3.1.2-2. Densities of Dominant Bivalve Veliger Larvae in 76-pm Mesh Not Collections on or Near the Same Date at Near- {
field Station, P2, and Entrainment Station, Ei, April Through June 1987. . . . . . . . . . . . . . . . . . . . 85 3.1.3-1. Seasonal Groupa Formed by Normal Classification of 4 Macrozooplankton Collections From Nearfield Station P2, 1978-1984, end by Discriminant Analysis of l
Collections From July 1986-December 1987 . . . . . . . . 90 q I
l 1
xvi
i
/
PAGE 3.1.3-2. Mean Abundance and Percent Frequency of Occurrence of Dominant Taxa Occurring in Seasonal Groups Formed by f Normal Classification of Necrozooplankton Collections l
at Nearfield Station P2, 1978-1984, in Comparison to 1986 (July-December) and 1987 (January-December) as l Classified by Discriminant Analysis. . . . . . . . . 91 I
3.1.3-3. Comparison of Percent Composition (and Percent Frequency of Occurrence) of Species in Macrozooplankton Collections Among Stations P2, P5 and P7, January-December 1987. . . . . . . . . . . . . . . . . . . . . 95 3.1.3-4. Summary of 1987 Biweekly Abundance Comparisons Between Stations Made Using Wilcoxon's Two Sample Test . . . . 96 3.1.3-5. Comparison of Rank (and Percent Frequency of Occurrence)
' of Deminant Species in Macrozooplankton Collections Among Stations P2, P5 and P7 January-December 1987 . . 97 3
) 3.1.3-6. Annual Geometric Mean Abundance (No./1000m ) and Upper and Lower 95% Confidence Limits of Selected Species of Macrozooplankton et Seabrook Nearfield Station (P2),
1978-1984 and 1987 . . . . . . . . . . . . . . . . . . 99 3.1.3-7. Results of One-Way Analysis of Variance Among Years for Selected Species of Macrozooplankton at Nearfield Station P2, 1978-1984 and 1987 . . . . . . . . . . . . 101 3.2.1-1. Distribution Among Weeks and Among Seasonal Assemblages of Samples of Fish Eggs Collected at Nearfield Stations P2 During January 1976 Through December 1987. . . . . . . . . . . . . . . . . . . . . 108 3.2.1-2. Distribution Among Weeks and Among Seasonal Assemblages of Samples of Fish Larvae Collected at Nearfield Stations P2 During January 1976 Through December 1987. . . . . . . . . . . . . . . . . . . . 115 3.2.1-3. Comparison of Percent Abundance and Percent l Frequency of Fish Egg Collections at Nearfield l (P2), Farfield (P7), and Discharge (PS) Stations During 1987. . . . . . . . . . . . . . . . . . . . . . 121 3.2.1-4. Comparison of Percent Abundance and Percent Frequency of Larval Fish Species at Nearfield (P2), Farfield (P7) and Discharge (PS) Stations During 1987. . . . . . . . 122 I
l l
i xvil
3 l
1 Pl.GE 1 3.2.1-5. Summary of Monthly Flow (Millions of Gallons per day) through the Seabrook Circulating Water System, ,
January-June 1987. .. . . . . . . . . . . . . . . . . . 123 3.2.1-6. Ichthyoplankton Sampling Dates at Entrainment (E1) and Nearfield (P2) Sampling Stations, January-June 1987 . . . . . . . . . . . . . . . . . . . . . . . . . . 125 3
3.2.1-7. Mean Abundance (No./1000m ) of Fish Eggs per Month at Stations El and P2, July 1986-June 1987. .. . . . . . . 126 3
3.2.1-8. Mean Abundance (No./1000m )'of Fish Larvae per Month at j Stations El and P2 . . . . . . . . . . . . . . . . . . . 129 ;
k 3.2.1-9. Geometric Mean of Seasons of Peak Abundance (Number per i 1000 m ) by Year of Selected Fish Species Larvae at .
Station P2 July 1975'through December 1987 . . . . . . . 133 j 3.2.1-10. Results of One-WayAbundances log'(x+1) Transformed Analysis o'f(No./1000 Variance m among) of years of Selected Species During Selected Months, July 1985 .
Through December 1987. . . . . . . . . . . . . . . . . . 134 3.2.2-1. Total Percent Composition by Year and All Years Combined j for the Twelve Most Abundant Species in Otter Trawls During 1976 through 1987 at Stations T1, T2 and T3 Combined . . . . . . . . . . . . . . . . . . . . . . . . 145 1
3.2.2-2. Total Percent Composition by Station of Abundant Species Collected in Otter Trawls, All Years Combined (1976-1987). . . . . . . . . . . . . . . . . . . . . . . 148 .g 3.2.2-3. Total Percent Composition by Year and All Years )
Combined for the Ten Most Abundant Species _in Gill '
Net Samples During 1976 through 1987 at Stations G1, G2 and G3 Combined . . . . . . . . .. . . . . . . . . . 151 3.2.2-4. Total Percent Composition by Station of Abundant Species Collected in Gill Nets, All Years and Depths Combined (1976-1987) . . . . . . . . . . . . . . . . . . 153 1 l
! 3.2.2-5. Total Percent Composition of Dominant Gill Net Species According to Depth (Surface and Off-bottom), All Years Combined (1976-1987) . . . . . . . . . . . . . . . . . . 154 3.2.2-6. Catch Per Unit Effort by Depth for the Dominant Gill Net Species over All Stations and Dates When Surface, Mid-Depth and Bottom Nets were Sampled, 1980 through t 1987 . . . . . . . . . . . . . . . . . . . . . . . . . . 156 xvill L
I PAGE
)
3.2.2-7. Total Percent Composition by Year for the Ten Most Abundant, Species Collected in Beach Seines During i
1976 through 1987 (excluding 1985 and 1986) at Stations S1, S2 and S3 Combined. . . . . . . . . . . . . 158 r
( 3.2.2-8. Total Percent Composition by Station of Abundant Species Collected in Beach Seines, All Years Combined, l
) April through November (1976-1984, 1987) . . . . . . . . 160 l 3.2.2-9. Annual Geometric Mean CPUE for Selected Finfish Species. 164 3.2.2-10. Results of One-Way Analysis of Variance Among Years of
)- Log (x+1) Transformed Catch per Unit Effort for Selected Finfish Species for all Gill Net Stations Combined l During 1976-1987 . . . . . . . . . . . . . . . . . . . . 165 3.2.2-11. Results of One-Way Analysis of Variance Among Years of Log (x+1) Transformed Catch per Unit Effort for Selected f Finfish Species at Otter Trawl Station T1, During 1976-1987. . . . . . . . . . . . . . . . . . . . . . 170 3.2.2-12. Results of One-Way Analysis of Variance Among Years of Iog (x+1) Transformed Catch per Unit Effort for Selected Finfish Species for all Beach Seine Stations Combined During 1976-1984 and 1987. . . . . . . . . . . . . . . . 174 3.3.1-1 Annual Mean Temperature ('C) and Salinity (ppt) at Beth High and Low Slack Tide from Brown's River and Hampton Harbor from 1980-1987. . . . . . . . . . . . . . . . . . 187 3.3.1-2 Total Precipitation (Water Equivalent in Inches) by
) Month and Year Taken At Logan International Airport, Boston, MA from January 1978 - December 1987 . . . . . . 188 3.3.1-3 Mean Number of Taxa and the Geometric Mean Density (No./m8 ) for Each Year and Overall Years With 95%
l Confidence Limits for Estuarine Stations at Brown's River (3) and Mill Creek (9) Sampled From 1978 Through 1987 (excluding 1985). . . . . . . . . . . . . . . . . . 194 1
3.3.1-4 Results of a paired t-test for Selected Biological Variablaes from Paired Subtidal (Sta. 3-Sta. 9) and Intertidal (Sta. 3MLW-Sta. 9MWL) Stations Sampled Three Times per Year During 1978-1987,(excluding 1985) . . . . 198 3.3.2-1 Relative Abundance of Dominant Macroalgae at Marine Bnnthic Stations in August of the Three Most Recent Years (1985, 1986 and 1987). . . . . . . . . . . . . . . 212 xix
f l
PAGE q 3.3.2-2 Summary of Spatial Associations Identified From Numerical Classification (1978-1984) and Verified with Discriminate Analysis (1978-1987) of Benthic Macroalgae !
Samples Collected in August. . . . . . . . . . . . . . 213 3.3.2-3 Probability of 1978-1987 Macroalgae Sample Membership in Each Station Group Identified From Numerical Classi-fication (cluster analysis) of 1978-1987 August Benthic Data . . . . . . . . . . . . . . . . . . . . .. 217 3.3.2-4 Season and Yearly Mean Abundance and Percent Cover of /
Laminarla Saccharino From Transect Studies in The Shallow Subtidal Zone. . . . . . . . . . . . . . . . . . . . . . 224 3.3.2-5 Results of Significance Tests on Macroalgae Selected Species, Chondrus crispus and Laminaria saccherina . . . 225 3.3.2-6 Mean Blomass (g/m 2
) and Standard Deviation (SD) of Chondrus crispus at Benthic Stations 17, 35, 1HLW, and 5MLW in August from 1978 to 1987 . . . . . . . . . . . . 228 [
\
3.3.3-1 Station Groups Defined by Discriminant Analysis of Non-colonial Macrofauna Collected at Intertidal and j Subtidal Benthic Stations, August 1978-1987. . . . . . . 237 ,
3.3.3-2 Median and Range of Percent Frequencies of the Dominant Fauna at Bare Rock, Fuccid Ledge and Chondrus zone Intertidal Sites at Stations 1 (Outer Sunk Rocks) and 5 (Rye Ledge) Monitored Nondestructively . . . . . . . . 241 3.3.3-3 Estimated Density (per 1/4 m 2) of Helected Sessile l Taxa on Triannual (4 Months' Exposure) Mard-Substrate Bottom Panels. . . . . . . . . . . . . . . . . 245 .
(
3.3.3-4 Annual Mean Density (Per 1/4 m2 ) and Standard Deviation of Nodlolus modlolus observed at Subtidal Transect Stations, 1980-1987. . . . . . . . . . . . . . . . . . . 247 f
3.3.4-1 Dry Weight (g/ Panel) Biomass on Short-Term Surface '
Fouling Panels by Year, Station and Month. . . . . . . . 252 l 3.3.4-2 Differences Observed on 1987 Nearfield Short-Term Panels l Compared to Baseline Period (1978-1986), and to Far-field Stations . . . . . . . . . . . . . . . . . . . . . 253 3.3.4-3 Dry Weight (g/ Panel) Biomass on Monthly Sequential Surface Fouling Pancis by Year, Station and Month. . . . 257 3.3.4-4 Laminarla sp. Counts on Monthly Sequential Surface Fouling Panels by Area, Station, Year and Month. . . . . 260 XX l
PAGE 3.3.5-1 Annual Geometric Mean of the Abundance (No./m8 ) of Selected Benthic Species Sampled Triannually in May, August, and November from 1978 through 1987. . . . . . . 262 3.3.5-2 Results of One-Way Analysis of Variance Among Years for I
the Log (x+1) Transformed Density (No./ms ) of Selected Benthic Species Sampled from 1978 through 1987 . . . . . 263 i
Annual Mean Length (mm) and the 95% Confidence Interval
) 3.3.5-3 l
( (CI) for Selected Benthic Species Sampled Triannually in May August, and November at Selected Benthic Stations from 1982 through 1987. . . . . . . . . . . . . . . . . . 266 3.3.6-1 Percent Composition of Lobster Larvae Stages at i Stations P2, P5 and P7, 1978-1987. . . . . . . . . . . . 275 l l
3.3.6-2 Summary of Total Lobster Catch Per Trip Effort, by 1 Month and Year, at the Discharge Site (4) from 1974 j through 1987 . . . . . . . . . . . . . . . . . . . . . . 279 3.3.6-3 Results of One-way ANOVA at the Discharge Site for Lobster (#, americanus), Jonah Crab (C. borea11s) and Rock Crab (C. Irroratus) . . . . . . . . . . . . . . . . 281 3.3.6-4 Paired t-test Comparisons of the Discharge Site (L1) and the Fairfield Station (L7) for Lobster (N.
americanus), Jonah Crab (C. borealis) and Rock ;
Crab (C. frroratus). . . . . . . . . . . . . . . . . . . 282 1 3.3.6-5 Comparison of Crab Catch Statistics of Jonah Crab (Cancer borealls) and Rock Crab (Cancer 1rroratus) at the Discharge Site and Rye Ledge, 1982-1987 . . . . . 290 3.3.7-1 Average Catch per Unit Effort, Percent Female, and Percent Gravid Females for Carcinus maenas Collected at Estuarine Stations from 1977-1987. . . . . . . . . . . . 307 3.3.7-2 Estimated Distribution (Percent of Total) of Clam i Diggers by Flat at Hampton Harbor, Spring 1980 through Fall 1987. . . . . . . . . . . . . . . . . . . . . . . . 311 3.3.7-3 Summary of Standing Crop Estimates of Adult Nya arenarla in Hampton Harbor, 1967 through 1987. . . . . . 314 xxi
i PAGE 3.3.7-4 Distribution (Percent of Total Standing Crop) of Harvestable Clams by Flat at Hamptcn Harbor, 1979 through 1987 . . . . . . . . . . . . . . . . . . . . . . 316 4.1-1 Benthic Station Locations and Descriptions . . . . . . . 350 4.2-1 Summary of Community Analyses. . . . . . . . . . . . . 357 4.3-1 Analysis of Temporal and Spatial Patterns in Selected Taxa and Parameters: Methods and Data Calculations. . . 362 l
I l
l xxii
i LIST OF APPENDIX TABLES PAGE 3.2.1-1 Finfish Species Composition'by Life Stage and Gear, July 1975-December 1987. . . .'. . . . . . . . . . . . . 179-h 3.3.1-1 ' Month Monthly' Seawater Surface Temperature ("C) and Salinity (ppt) Taken 'In Brown's River and llampton
) Harbor, May 1979.- December 1987 . . . . . . . . . .. . 318 i
I' 3.3.2-1 Macroalgae Species Recorded in General Collections From Benthic Stations Sampled From 1978 to 1987 (a,b,e). 319
/ 3.3.2-2 Sparsely Occurring (< 5% frequency of occurrence)
Macroalgae Taxa in August Benthic Destructive Samples, 1978-1987. . . . . . . . . . . . . . . . . . . . . . . . . 323 3.3.2-3 A. Percent Frequency of Perennial and Annual Macroalgae Species and B. Percent Cover of perennial macroalgae
) species per 0.25 m2 at Fixed intertidal Non-Destructive Sites. . . . . . . . . . . . . . . . . . . . . . . . 324 3.3.3-1 Species Used in Discriminant Analysis of Benthic Macrofauna . . . . . . . . . . . . . . . . . . . . . . 329 3.3.4-1 Number (mean per two replicates) of Selected Non-Colonial Species occurring on Short-term Fouling Panels by Month, Station, and Year. . . . . . . . . . . . . . . . . . . . 330' 3.3.4-2 Percent Frequency Occurrence (mean per two replicates) of Selected Colonial Species occurring on Short-term Fouling Panels by Month, Station and Year. . . . . . . . 340 3.3.6-1 Summary of Legal Lobster Catch at the Discharge Site from 1974 through 1987 . . . . . . . . . . . . . . . . . 343 3.3.7-1 Summary of Nya arenarla Population Densities from l Annual Fall Surveys in llampton-Seabrook Harbor, 1973 through 1987 . . . . . . . . . . . . . . . . . . . . . . 344 !
'i i
xxill
\;
p.
1 1.0 EXECUTIVE
SUMMARY
1.1 INTRODUCTION
Seabrook Environmental Studies began in 1969 to monitor the balanced indigenous marine communities in preparation for assessing the-f ef fects of Seabrook Station operation. As plant operation has not yet begun,-
j the study is in the preoperational or baseline. monitoring phase.
The purpose-of the 1987 Seabrook Baseline Report is to define the f sources and magnitudes of naturally-occurring variability in the physical and biological environment around Seabrook Station. A previous report (The 1986 l-Seabrook Baseline Report) summarized information collected through 1986.
This report updates those results with one additional year of data.
The optimal design of an impact assessment study ensures that a potential impact is delineated from naturally-occurring verlability. The Seabrook Monitoring Program accomplishes this by (1) collecting data before and during operation to provide a " temporal control", and by (2) monitoring areas of potential impact as well as areas outside the influence of the j thermal plume to provide a " spatial control". In each biological community, ,
l the experimental design of the program focuses on the most variable aspect. l For example, the species distributions of plankton and pelagic fish change l radically from season to season, but are similar throughout the coastal. area. )
The sampling program collected data at least twice monthly to monitor. sea- ;
sonal trends in abundance at a nearfield and farfield area. For benthic- l l
macrofauna and macroalgae, seasonality is less of an issue.in comparison to l the marked changes in species composition with depth and. substrate. Benthic collections were made in the predominant substrate type, horizontal hard' l bottom ledge, along nearfield and farfield transects at regular depth inter-vals. The American lobster, soft-shell clam, and certain fish are of partic- :
ular concern because of their commercial or recreational importance. Data on !
all life stages of these species were collected. The discussion of vari-ability focuses on the source of potential impact (intake, discharge) and the
, biological community or physica1' parameter mos't likely to be affected.
1
1.2 INTAKE MONITORING The goal of intake monitoring is to provide information on the number and type of organisms entrained or impinged by the Seabrook Station cooling water system. Zooplankton, ichthyoplankton, and pelagic fish are the organisms which have the greatest potential for exposure to intake effects.
During the study, both the number and type of entrainable organisms varied dramatically among seasons. The microzooplankton community shifted from a community predominated by copepods in spring, to one where bivalve larvae were most abundant in summer, to a low-density tintinnid community in fall and winter. Each year was slightly different from the previous depending on the natural thermal regime. Macrozooplankton assemblages were highly predictable from year to year, reflecting the population dynamics of the dominant copepods and the spring and summer reproductive activities of benthic fauna. Seasonal patterns of the bivalve larvae (including mussel and soft shell clam larvae) and the fish egg and larvae species assemblages were the result of spawning activities of the adults. Species composition reflected the predominance of one or two species which were present during a discrete time period. Fish eggs were most abundant in spring and summer, bivalve larvae in summer and fall, and fish larvae in late winter and summer.
Most of the species that were represented in the zooplankton of the study area are widely distributed throughout the Gulf of Maine; thus entrainment losses can be replenished by the nearshore populations. Two species with local adult populations contributing to the larval pool, cunner and soft-shell clam, have widespread nearshore larval populaticus, which lessens the potential for entrainment impact.
Beginning in June 1996, Seabrook Station operated its cooling water system, although no power or heated discharge were produced. As expected, entrainment samples collected in the last half of 1986 and the first half of 1987 had species compositions of fish eggs, fish larvae, and bivalve larvae that were similar to samples collected offshore. Density levels for most of the entrained fish eggs and larvae were lower because the plant intake is not at the depth where ichthyoplankton are most concentrated. Species diversity 2
l l - - - _ _ - _ _ _ _ _ _ - - _ _ . _ _ - _ _ . . _ _
of ichthyoplankton entrainment samples was lower because of the less inten-sive sampling effort. Density IcVels of bivalve larvae were similar to those offshore except during peak abundance periods, when entrained densities were lower.
Potential intake effects on the pelagic fish community may be apparent from studying the seasonal and annual movements of the six most abundant species, which together constitute over 90% of the population. Of these, Atlantic herring is the most important; from September to April, it makes up from 60-90% of the total gill net catch. The variability in overall catches was directly related to year-to-year variations in Atlantic herring catches. Another important consideration in intake effects is the depth distribution of the pelagic fish. Atlantic menhaden and occasionally Atlantic mackerel were more abundant in the mid-depth area, where intake structures are located, than they were at the surface or at the bottom.
These species may potentially be more susceptible than other pelagic fish to intake effects. Benthic oriented (demersel) fish also may be affected by the intakes if (1) they make excursions off the bottom in search of food and/or (2) they perceive the intake structures as protective or food-bearing habitat. The characteristics of the demersal fish communities in the study area are discussed below.
To evaluate the impact of operation of the Circulating Water System on adult and juvenile pelagic and demersal fish species, impingement samples were obtained and evaluated by Seabrook Station personnel. Monitoring to date has identified that approximately 0.02 fish per million gallons of cooling water flow (1 fish /50 million gallons) will be impinged at Seabrook Station. These studies strongly suggest that the design and operation of the intake structures will protect the balanced indigenous fish population by minimizing the number of individuals entrained within the system and subse-quently impinged upon the travelling screens.
3
1.3 DISCHARGE MONITORING 1.3.1 Discharge Plume Monitoring As the discharge plume will be concentrated in surface and near-surface waters, impact assessment will focus on parameters and organisms which are located primarily in this zone. Surface water quality, phyto-plankton, and lobster larvae have been monitored primarily for determining potential discharge plume effects. Water quality parameters have histor-ically shown distinct seasonal patterns that were important in driving biologic-; e.ycles. Surface and bottom temperatures reached their lowest points from January through March, then steadily increased from August to October before beginning their fall decline. Dissolved oxygen had a seasonal pattern that was inversely related to temperature, with peak values in late winter and lowest values in fall. Year-to-year differences were low.
Salinity values were fairly stab: y but highest in winter and lowest in spring, a result of high runoff. Nutrients had somewhat erratic seasonal cycles, but were generally lowest in summer and highest in fall and winter.
In general, the predictability of seasonal patterns and low year-to-year variability of most of the water quality parameters enhances their suit-ability for impact assessment.
The phytoplankton community has st a the most seasonal and annual variability of any of the species assemblaps .snitored. Species composition during peak periods varied from year to year. However, total phytoplankton abundance and chlorophyll a were relatively similar among years and showed a predictable seasonal cycle. Increases in irradiance typically initiated the spring bloom; densities usually decreased upon the decline in nitrogen-nutrients, coincident with thermocline development. Densities usually showed another increase in late-summer or fall. The phytoplankter Conyaular sp.
produces paralytic shellfish poisoning, or red tide in this and other coastal areas. This organism usually reached toxic levels (as measured in #ytilus edu11s meat) in May or June in Hampton Harbor, closing flats to bivalve shellfish fishing for a period of one to seven weeks each year.
f I
Lobster larvae (Stages 7-IV) have a strictly surface orientation.
In coastal New Hampshire, successful recruitment of larvae is the single
- biggest factor in determining the level of adult catches. All stages were
( rare in the study area, generally occurring from June to October, with highest densities from late June through late August. Evidence suggests that waters off Hampton-Seabrook may be too cold for local production of lobster 5
1arvae, and those collected off Hampton-Seabrook actually originate from elsewhere in the Gulf of Maine and from Georges Bank.
L Subsurface fouling panels, located three meters below the surface, placed in the discharge plume area show timing, type, and abundances of settling benthic organisms. Benthic recruitment and community development have shown a seasonal pattern that was highly consistent from year to year.
Recruitment and settling activity was low in winter end spring but intensi-fled from summer through fall.
The intertidal and shallow subtidal area near Sunk Rocks is outside the immediate plume area but might be exposed to slight elevations in tem-perature. Species composition of benthic macroalgae and macrofaunal com-munities in the intertidal and shallow subtidal areas changed with depth and substrate, but was highly similar among years. Individual species showed significant variations in recruitment levels from year to year and among stations. Macrofauna length measurements, however, were a more stable parameter.
1.3.2 Benthic Monitorin; The mid-depth and deep subtidal areas are monitored to determine if, during operation, any discharge impacts result from increased detritus levels. Year-to year differences in the macroalgae and macrofaunal commun-ities have been small in comparison to variations with depth and substrate.
The species composition was highly predictable and distinct for each depth zonn. Although individual macrofauna species appeared highly variable in 5
their annual abundance levels, these differences were usually not signifi-cant. Length measurements were not as variable as abundances and showed no differences among years.
Demersal fish which inhabit or feed in the discharge area are important because of their predominance in the food chain as well as for their commercial value. Six taxa constituted over 80% of the total otter trawl catch. Long term trends in total catch were evident, as catches in 1980 and 1981 were almost twice catches during the lowest years, 1977 and 1985. The demersal fish species composition basically changed twice per year, from a winter assemblage, when rainbow smelt were abundant, to an extended summer arsemblage (April-November), when hakes and longhorn sculpin were abundant. Other dominants such as yellowtail and winter flounder were present year-round. Most of the fish captured, with the exception of hakes and winter flounder, were juveniles. (
Because of its commercial importance, the American lobster was monitored in the dischargo area. Seasonal patterns in catches were similar from year to year, and were affected by bottom temperatures, which influenced molting and activity levels. Catches usually increased to a peak in August or September, then declined. Decreases in catches in 1984 and 1985 of legal sized lobsters, a primary concern to lobstermen, were a result of natural variation in combination with the effects of the change in the legal size limit instituted in 1984 by the State of New Hampshire. Lobsters which would have been of legal size under the old law were protected from harvest until their next molt. The catches of lobster in 1987 were the lowest of any year during the 1975-1987 study period, showing a low total catch and low propor-tion of the catch that was of legal size, 1.3.3 Estuarine Monitoring Although the likelihood of a cooling water system operational impact on the llampton-Seabrook estuary is low, temperature, salinity, benthos, fish, and the soft-shell clam were all monitored in this area.
6
)
Temperature and salinity both showed regular seasonal cycles.
Maximum temperatures usually occurred in August.with minima in January or February. Salinity levels had a less distinct pattern, but were usually p lowest in spring, a result of increased. runoff, and highest in summer.
Salinity levels in Brown's River were high from'1980-1981 coincident with
~
low precipitation levels and highest discharge volumes of tunnel dewatering through the Seabrook settling basin. By'1986, salinity' levels had returned to pre-1980 levels. The estuarine benthic community was highly variable in species composition and abundance, but predominantly composed of surface and subsurface deposit-feeding polychaetes. The number of species, total abundance, and abundance of some of the dominant species increased during the period when salinity levels were higher than average, but have returned to the levels observed prior to the tunnel dewatering discharge.
Estuarine fish included anadromous species as well as residents.
Alewives and blueback herring pass into the estuary in spring, travelling upriver to spawn. Catch levels were affected by year class strength as well as water temperature and water level, which were influenced by-rainfall and resulting runoff. Young-of-the-year and yearling rainbow smelt were occasionally and erratically caught in the estuary, but never constituted a substantial portion of the total catch. The predominant resident species was Atlantic silverside, which made up over two-thirds of the total catch and over 90% during their most abundant period, August through November. Varia-tions in abundance of this species was the cingle most important factor in year-to-year changes in total catch.
The species of greatest concern in the Hampton-Seabrook estuary is l the soft-shell clam. Density levels of spat, juveniles, and adults have been 1
monitored in the estuary for 17 years. Densities of harvestable clams depend l
on a set of complex, interacting conditions. A successful set of spat is
! crucial, but this factor alone does not ensure high densities of harvestable l
clams. Once settled, survival of young-of-the year clams depends on protec-tion from its two main predators, green crabs and humans, as well as from 7
disease. In 1976, a large spatfall throughout the estuary resulted in high densities of harvestable c: cos in 1980-1982. Increased levels of predation prevented recruitment of the highly successful spatfalls in 1980 and 1981.
Light spatfalls from 1982-1986 in combination with an increase in predation accounted for a precipitous decline in standing stock since 1983 and ensure that densities of harvestable clams will remain low for several more years.
In addition, neoplasia, a cell growth disease fatal to clams, has been detected from clams in Hampton estuary. This may also be contributing to the decline of harvestable clams, 1
(
1 l
l 8
l 1
)
2.0 DISCUSSION I J .-
2.1 INTRODUCTION
2.1.1 General Perspective Environmental studies for Seabrook Station began in 1969 and focused on plant design and siting questions. Once these questions were resolved, a monitoring program was designed which has examined the structure of all the major biological communities as well as the distribution, abundance, and size of selected species within each community. The goal has {
been to assess the temporal (seasonal and yearly) and spatial (nearfield and ]
farfield) variability which has occurred during the baseline period. This report focuses on data co13ccted since 1976 for fisheries studies and since 1978 for plankton and benthos studies as these years have maintained a con-sistent sampling design.
The purpose of this report is twofold: (1) to update results of the preoperational baseline monitoring program, suitmarized in NAI (1987b) with one additional year of data, and (2) provide a perspective on the sources and magnitude of naturally-occurring variability against which impact assessment will be made. Variability is important because it is the issue on 1 which sampling design is focused and can bn a major impediment to meaningful impact assessment. Therefore it is discussed first.
2.1.2 Sources of Baseline Variability The optimal design of an impact study has four prerequisites that ensure that a potential impact is delineated from any naturally-occurring variability (Gretn 1979): (1) knowledge of the type, time and place of potential impact; (2) measurement of relevant environmental and biological variables; (3) monitoring before the potential impact occurs to provide a -
temporal control; (4) monitoring in an area unaffected by impact to serve as 9
i a spatial control. The experimental design of the Seabrook Environmental Program was structured to meet these prerequisites.
A basic assumption was that there are two major sources of naturally-occurring variability: (1) that which occurs among different areas or stations, i.e., spatial, and (2) that which varies in time, from daily to weekly, monthly or annually. In the experimental design and analysis, we focused on the major source of variability in each community type and then determined the magnitude of variability in each community (Figure 2.1-1). In certain communities: particularly planktonic, where circulation patterns provide a similar habitat throughout the area, spatial variability was low in comparison to seasonal. The study design therefore focuses on frequent sampling to monitor seasonal trends at only one nearfield and one farfield station. In other communities, particularly benthic, spatial variability has been higher than seasonal variability. Benthic sampling design has focused l on the dominant substrate type in the discharge area, horizontal hard-bottom ledge, with paired nearfield and farfield stations representing the major depth zones. Finfish catches have shown both seasonal and spatial dif-Cerences. Therefore, these studies make frequent (at least monthly) collec-tions in the area of the discharge as well as farfield areas to the north and south. Because the estuary is an aquatic nursery area and recreationally-important clam flat, baseline collections monitoring seasonal and annual patterns were also made there for operational phase comparison, j Biological variability can be measured on two levels: species and community. A species' abundance, recruitment, size and/or growth are important for understanding operational impact, if any. For this reason, these parameters were monitored for selected species from each community
{ type. Species were chosen for more intensive study based on their commercial or numerical importance, sensitivity to temperature, potential as a nuisance organism, and habitat preference. Overall community structure, e.g., the number and type of species, total abundancc and/or the dominance structure, may also be affected by plant operation in a way not detectable by monitoring 10
SOURCES OF VARIABILITY
)
TEMPORAL PREOPERATIONAL OPERATIONAL
- W P
S o N - .
d N '
g N; . ,
5 N_ ,' -
g s 7
\ 's N '
l
\ ,'
s 's !
g x .
\
\ v i: YEAR. S . .
3 s
\ L. l .n...n..! [.....J.l:.iinnA.l
. .'.. 4 I<lIs Elt. ..msl..'in.n.nl. 6,sl )
l \ -
\\ ' ' ', ,,, , ', . l l s :pe i
\
1d o .
];
s
\ ,,,l,.(l~..,l,, il N l .
\ i
( MONTHS / WEEKS ;
\ l
\ l
\ i l
i LEVELS OF VARIABILITY l SPECIES ASSEMBLAGE l
l l
DOMINANTS NONDOMINANTS MULTIVARIATli NUMERICAL CLASSIFICATION ANALYSIS DISCRIMINANT FUNCTION ANALYSIS i
l
\
SELECTED SPEC!ES
\ ,
f UNIVARIATE TIME SERIES ANALYSIS ANOVA 1
( Figure 2.1 1. Schematic of sources and levels of variability in Seabrook Envimnmental Studies.
Seabmok Baseline Repon,1987.
11
(
single species; therefore, the natural variation in community structure was monitored at regular time intervals, determined by early' studies to be sufficient for this purpose.
1 Appropriate statistical methods must be used in conjunction with a well planned experimental design in order to determine the sources and magnitude of variability. Annual and spatial variability in species abundance and size were tested by using analysis of variance or nonparametric i analysis which will provide a means of evaluating the statistical signifi- i cance of changes in the operational period. Spatial, seasonal, and annual variations in community structure were assessed first with numerical classi-fication and then with discriminant analysis. Discriminant analysis provides a set of criteria using the baseline collections against which operational phase collections may be compared.
Identification of the sources and levels of variability utilizing the methods discussed above has its ultimate focus on the sources of poten-tial influence from plant opera'; ion, and the sensitivity of a community or parameter to that influence (Table 2.1-1). Naturally, a community or species might be affected by more than one aspect of the cc:>1ing water system; however, the focus here is on the aspect of main concern. In general, intake (pumped) entrainment and impingement would potentially affect mainly plankton communities, including fish eggs and larvae, and pelagic fish. If they occur, thermal effects from the disuharge (e.g. plume entrainment) would most likely affect nearshore surface water quality, phytoplankton, and intertidal and shallow subtidal benthos. Although no effects are anticipated in the estuary from the offshore discharge, fish and soft-shell clam populations have been monitored in that area to provide a baseline for coerational phase comparisons. Bottom-dwelling organisms, including macrofauna, macroalgae, epibenthic crustaceans, and demersal fish, may be influenced by detritus potentially arising from moribund entrained plankton which is discharged with the cooling water. A previous impact assessment (NAI 1977e) has shown that the balanced indigenous community in the Seabrook study area should not be adversely influenced by the above factors. Results from the biological 12
TABLE 2.1-1.
SUMMARY
OF BIOLOGICAL COMMUNITIES AND SPECIES MONIl0 RED FOR EACH POTENTIAL IMPACT TYPE. SEABROOK BASELINE REPORT, 1987.
l l
I LEVEL MONITORED
{ SELECTED f MONITORING SPECIES /
AREA IMPACT TYPE SAMPLE TYPE COMMUNITY PARAMETERS l
I Intake Entrainment Microzooplankton x x Macrozooplankton x x
! Fish eggs x
! Fish larvae x x Soft-shell clam larvae x Cancer crab larvae x Impingement Pelagic fish x x Discharge Thermal Plume Nearshore water l quality x l Phytoplankton x x Lobster larvae x Intertidal / shallow subtidal macroalgae and macrofauna x x Subsurface fouling community x x Plume Discharge Mid-depth / deep macrofauna and macroalgae x x Bottom fouling community x Demersal fish x x Lobster adults x Cancer crab adults x Estuary Cumulative Sources Estuarine temperature x Soft-shell clam spat and adults x Estuarine fish x x 13
communities, species and environmental parameters sampled will be discussed in light of the feature of the cooling water system which would have tho greatest potential for affecting them.
i i
l 14 0
?
i 2.2 INTAKE AREA MONITORING 2.2.1 Plankton 2.2.1.1 Community Structure An estimation of the number and type of plankton species affected
! by plant operation will depend on (1) the time of year, and (2) the degree of yearly variability. Results from the community analysis give an indication of the number and type of species present (and thus entre.inable) at any particular time of year. These provide a multivariate " template" against which seasonal assemblages during plant operation may be compared. The l selected species analysis enables a more precise estimate of the entrainable density for key species by examining their annual and seasonal variability.
Knowledge of the within-year and among-year variability allows for more reliable estimates of impact to be made than if entrainment samples were taken in a single season and year.
All of the planktonic communities had species assemblages that changed with season during the baseline period (Figure 2.2-1). These groups were dif ferentiated primarily on the distribution and abundance of dominant species; however, the relative abundance or even absence of other species was also a factor. The type of species entrained will depend on the seasonal assemblage present at the time. Macrozooplankton assemblages have been distinct and consistent, showing high predictability from year-to year.
Macrozooplankton assemblages reflected mainly the population dynamics of the dominant copepods with reproductive activities of benthic organisms affecting spring and summer species composition. In 1987, each macrozooplankton sample j exhibited the same species assemblage that had been present at that time of 1
year during the collections in previous years. There were some shifts in species composition within those assemblages compared to the earlier years.
Centropages typicus in uinter and spring and Calanus finnarchicus in summer both showed reduced importance in the macrozooplankton communities sampled in 1987.
15
3 MICROZOOPLANKTON (NoJm )
, , , , , t 1 I f i t J l F l M l A l M l J l J l A ,l $ l 0 l N l 0 w
O
\ .
U t
3 MACROZOOPLANKTON(NoJ1000m )
, , , , , , , , , , , KEY J l f l M l A l M l J j J l A l $ l 0 l N l 0 MEAN SEASONAL GROUT 6-- ABUNDANCE s
o to-1m v- O 'ot-' o =
1.001 1o.000 FISH EGGS (NoJ1000m 3 )
, , , , , , , , , , , 10 # 1-1 " o
- J l 8 l M l A l M' l J l J l A l $ l C l N l 0 l l
, > 100.000 I '
( . n .
- DATES OF OCCURRENCE v -
FISH LARVAE (NoJ1000m3 )
J l F l M l A l M l J l J l A l 5 l 0 jn j D n
g
. A .
m v
V O-O .
n U
{t--C : :
3 .
Figure 2.2-1. Historical dates of occurrence and mean abundance (excluding rare taxa) i for seasonal groups formed by numerical classification of microzooplankton (No/m ,1978-1984), macrozooplankton (NoJ1000 m ,1978-1984), fish eggs (NoJ1000 m ,1976-1984), and fish larvae (NoJ1000 m 1976-1984) -
collections. Seabrook Baseline Report,1987. ;
16
i
)
Microzooplankton and planktonic fish eggs had several overlapping i groups in spring and summer, indicative of both some year-to year changes in community structure as well as a variable " transition period" in the late j summer assemblage (Figure 2.2-1). The microzooplankton community typically shifted from one characterized rotifers in the spring, bivalve larvae in the f summer, copepods in the fall, and tintinnids in the winter (NAI 1987b). Fish egg collections in 1987 were generally similar to previous years in their species composition and density. Exceptions in 1987 to the previously L
observed pattern were (1) absence of the previously important summer cunner-yellowtail flounder-hake assemblage, and (2) increased importance of two l
previously minor assemblages of late summer and fall species. The former was due to reduced abundances of two subdominant species in 1987, Atlantic mackerel and Atlantic whiting. The latter exception may have been influenced by the change in classification method from cluster analysis to discriminant analysis. Although species composition and abundances did not appear to differ substantially from past years, discriminant analysis placed greater emphasis on subdominant species in making group assignments, whereas cluster analysis emphasized the most abundant species.
Seasonal assemblages of fish larvae could be divided into four major types based on their dominant taxa: fall-winter (predominated by Atlantic herring), winter-spring (American sand lance), spring (winter flounder, sna11 fishes, and radiated shanny) and summer-fall (cunner). Varia-tions in density of the major taxa, especially during transition periods, caused small changes in species composition leading to the formation of overlapping " subgroups". Seasonal patterns observed in 1987 were similar to previous years (Figure 2.2-1). There was increased importance in 1987 of a spring sand lance assemblage and a summer cunner assemblage, both charac-terized by low densities.
The effects of plant operation will also depend on seasonal varia-tions in density. In most months, macrozooplankton densities have histori-cally been over 100,000/1000 m (Figure 2.2-1). The level of entrainment will be fairly consistent, although different species will be involved in each season. Microzooplankton (through 1984) and planktonic fish egg assem-17
blages (through 1987), on the other hand, had their greatest concentration in the spring and summer, when bivalve larvae and copepod nauplii (microzoo-plankton), and cunner eggs (fish eggs), were dominant, and group densities were three orders of magnitude higher than in winter (Figure 2.2-1). Simi-larly, fish larvae were most abundant in late winter, when sand lance pre-dominated, and summer, when cunner predominated. The level of entrainment for these assemblages will vary more dramatically between seasons in compari-son to the macrozooplankton communities. All of the dominant taxa typifying these planktonic assemblages in the vicinity of the Seabrook Station are widely distributed in the Gulf of Maine in either nearshore regions or open water. 'No groups, bivalve larvae and cunner larvae, have local adult populations contributing to the larval production; however, these species also have widespread nearshore populations which contribute to the total larval pool along this portion of the western Gulf of Maine.
Beginning in June 1986, Seabrook Station operated its circulating water cooling system; no power or heated discharge were produced. Initial sampling of entrained fish egg, larvae, and bivalve larvae communities revealed them to be similar to those collected offshore, although the smaller sample volumes and less-frequent sample collection in the plant produced some expected differences. The top-ranked entrained fish egg and larvao species were similar to those from offshore collections (Table 2.2-1); however, the total number of taxa was lower, due to the less-intensive sampling effort.
Abundances of most of the dominant species were lower in entrainment samples than in offshore samples, in some cases substantially so. This pattern is probably a result of the different depths represented by the two types of samples. Geabrook Station's cooling water entrains organisms at a point five meters above the bottom where the total water depth is 17 m, whereas the oblique offshore tows sample the entire water column. The depth distribution of ichthyoplankton is typically uneven, particularly for eggs of some species, which are heavily concentrated near the surface. Entrained bivalve 3 1arvac species were similar to those collected offshore; and, unlike the ichthyoplankton, densitien were very similar to those in offshore samples.
When samples from the same day were compared, no significant differences in bivalve larvae densities were detected.
i 18
{
}
TABLE 2.2-1. COMPARISON OF DENSITIES OF TOP-RANKED FISH EGG, FISH LARVAE, AND BIVALVF LARVAE TAXA COLLECTED OFFSHORE AT STATION P2 AND IN ENTRAINMENT SAMPLES AT SEABROOK STATION FROM JULY 1986 THROUGH JUNE 1987.
i SEABROOK BASELINE REPORT, 1987.
l DENSITY" l
l DOMINANT SPECIES ENTRAINED (E1) 0FFSHORE (P2) a Fish eggs Cunner /yellowtail flounder 169 3390 l Atlantic mackerel 107 1790
! Rockling/ hake 88 142 Atlantic cod / haddock / witch l flounder 73 102 American plaice 55 14 l
Windowpane 43 232 Hake 15 539 i
Pollock ,
12 4 Fourbeard rockling 9 228 a
Fish larvae i
Atlar. tic herring 127 110 Seasnail 23 33 American sand lance 17 56 Grubby 5 2 Rock gunnel 5 2 Winter flounder 5 20 American plaice 4 5 Bivalve larvae
! Hodlolus modiolus 3480 3910 l Heteranomia squamula 2520 2930 Hyt11us edulis 523 646 Mya arenaria 44 65 a
No./1g00m No./m
' Average of monthly averages computed to compensate for unequal numbers of samples 19
1 k
2.2.1.2 Selected Species c Nine species with various lifestages from the pelagic zooplank-ton communities were designated as selected species. The existence of seven to nine years of preoperational data allows an estimation of sea-sonal and annual variability. These species exhibited different degrees f
(
of numerical importance; their relative contributions to their respec-tive communities are shown in Figures 2.2-2 and 2.2-3.
The zooplankton selected species (including various life- ;
stages) historically have constituted less than 40% of the overall k abundances (Figures 2.2-2 and 2.2-3). In both the microzooplankton and macrozooplankton assemblages, other copepods typically have made a large contribution to overall abundances. In the microzooplankton, unidentified copepod nauplii and copepodites have been extremely abundant. In the macrozooplankton, copepods other than the selected species have historically been dominant over the year; however, the noncopepod selected species have 1 been dominants in certain seasons. All of the zooplankton selected species k reached peak abundance in spring and summer, with the exception of Neomysis I americana, which has been most abundant in winter / spring. {
Selected species of fish larvae predominated in every season, f constituting 79% of the total abundance overall (Figure 2.2-4). Generally, each of the species was present only for a brief time period that was fairly I
consistent from year to year. Timing of peaks in abundance in 1987 was consistent with previous years, with only minor variations. Sand lance abundance peaked a month earlier than usual. Atlantic cod, unique among these fish larvae in having two peaks per year rather than one, reached its highest abundance during the winter peak, which is usually secondary to the spring-summer peak.
(
l k
20
,}iIlI l1ll1!
)
gm>X u) A>Uog O " Q X 5 z4X(o -
"f0i .
"Oe .
p.
H c T
N C)
O .
M An
- 0i f
O - , , . , - - -
y gE%omp <>3 >g-[Q
~ Ae
^
7g '
- . 3l: ' -
J.
(.
ge : _- =-" ==
E :0 "
C -
N . .
A .- -
D ~
N o. ,
U t :
}
B . " -
A G = ,-
O ,
L .
is >rog _a a $
, o >r 95 gm* 3 a w R 2 O
AO i h Om4y7Om N
I O
T QO e I
3 rO 9 S
O g g P MO i M
O .
C "O e Oe m p
. i n s p p
p ps .
p u s a u s s s s eit s t s n i a m a e at s l
t et d l s s s at p ad s ri r a ue u n u no nl u o od e C ni t
n o a op o c mp o h st /
sI I lado las t h n h t
e ht de e ep p t
up a p al l l c u l I l a t s u c O Oo O m
y r o r d nu ope oda c e uc oa lea n d o d n E m a c
u e c u
e o o s s t t o P le y d P r
e u u k
E e S s P
1$Cn x
" . yn0mD Ooe3" n 0' mem* ge <m- mp$
- 6 45nwmc*wsn%
r
^ n >3 g-no o$7n+0" om y0 nx+~v m0$ @-ooO- mao ao3n*3m9 0, t@4 m'Oc5 $oe m@ ma 7o eo. mt $ e-$ om ox
- wnoOwmnXno3IL
^ woCm uom m om 7 D wne" ,vc ar0 o o O m3rnop- ^2o ~B v yucpi- pa n 8 m
c- = e $ an 8 # wmmS 7e 2oo0n' Uc9 -
,o H ll1 (,
PEAK SEASON 12 f
g..piipii o i i i z
k
{
l TEMPORAL VARIABILITY s- -
I u, 4- "
n {
g ..
l 3- . AuONG uOsms (n.12) n no o AMONG YEARS (n = 8 or 10) c I I{ ,, A AMONG WEEKS (n. 26) b A AMONG WEEKS (n .18) 3_
O f5 -
f
- m. IMPORTANCE z
O h 40 - ,
@ g BlVALVELARVAE 2
0 20 -
0 I i T-- T--" i i i 4 : : : :: a E.
!E i:
.:$2
!=E gB E o
'. !E eE n! !}$
E."
E o $5:$.
g jogcog 15 55 :E! $5 E a p jaog!} ! d.e n.d g !I a
Figure 2.2-3. Percent composition, seasonal vs. annual variability (standard deviation) of log (x+1) abundance, and 2m nths ofpeakabundanceforlobsterlarvae(No.f1000m)and selected zooplankton species of bivg)ive (No./1000 m .
larvae Seabrook(No./m ) and Baseline macro-Report, 1987.
22
PEAK SEASON O PEAK MONTHS 12 -
10 -
) z 8- E J
E 2- -
) O . . . . . . . . .
t
)
TEMPORAL VARIABILITY
} 3-s AMONG MONTHS (rm12)
, o AMONG YEARS (n=12 or 13)
Ei
} 52-
[
l @
S 1 1-
- ;,1 - "
,, ,;I ,,
J ,,
30 - IMPORTANCE z
h 20 -
a k
10 -
0 PP Y P I g I ig i" o3 5 2 $F t
- El 1 if E 2 RE a j -l 5 fj; $E EI Figure 2.2-4 Percent composition, seasonal vs. annual variability (standard dgviation) of log (x + 1) abundance (No./1000 m ), and months of peak abundance for selected species of fish larvae, 1975-1987.
Seabrook Baseline Report, 1987.
23
l
< The plankton selected species showed varying degrees of year-to-year differences in abundance. For the phytoplankton and microzooplankton, !
among year and within-year (seasonal) variations were about the same (Figure 2.2-2). Macrozooplankton, bivalve larvae, and lobster larvae (Figure 2.2-3) (
and fish larvae (Figure 2.2-4) usually showed higher seasonal variability
. 'than among-year variability. Cancer sp. larvae were an exception, with very high variation among as well as within years. Only three of the nine celected fish larvae species showed significant. differences among years. L These analyses indicate the species composition of entrained organisms may be fairly consistent over the years, although the actual number of organisms entrained could vary widely, particularly among seasons. ,
Bivalve larvae studies were carried out in the intake area to address questions related to the potential reduction in abundances of Mya ;
arenarla larvan because of entrainment. Local current regimes and length of .
time spent in the plankton imply that nearshore Nya larvae populations'origi- '
nate from spawning adult populations in local and more southern estuaries, j e.g., Hampton-Seabrook, Merrimack River and Essex, Massachusetts (NAI 1982b).
Spawning adults have been observed in Hampton Harbor and Plum Island Sound (a farfield site) typically from June through September, but as early as April and as late as the end of October in some years. Although larvae were observed throughout the spawning period, peak densities usually did not occur until August or September (Figure 2.2-3); secondary peaks also. occurred in May or June in some years. Therefore, the magnitude of entrainment will depend on the time of year as well as the overall annual abundance in that particular year. Initial entrainment samples. collected during the period of peak Nya larvae densities were similar in magnitude to those collected off-shore (Table 2.2-1). However, because larval densities in the nearshore area have shown no correlation with spat settlement densities (Section 2.3.1.3),
entrainment estimates cannot be used to determine the impact of plant opera-tion on the Hampton Harbor adult clam population.
24 L__ _ ---- -
)
2.2.1.3 Spatial Variability An optimal impact assessment design (Green 1979) has been used for f-
} intake monitoring where comparisons of nearfield and farfield samples in both the preoperational and operational periods will be made. A determination of f the similarity of nearfield and farfield plankton communities must be made in
)
order to ascertain the suitability of the farfield station as a " control"
( area. Previous analyses of the microzooplankton, macrozooplankton, and fish I
egg and larval communities showed that differences among seasons and even dates within season were greater than those between nearfield and farfield stations (Table 2.2-2). Examination of data collected in 1987 supported thest. results. The communities in all cases were highly similar among stations. At the species level, some spatial differences were detected. In the macrozooplankton, two taxa, Pontogenela inermis, and Diastylls sp., were more abundant at the nearfield intake station. This pattern may be due to a l more complex substrate, cobble and sands, at the nearfield station in com-parison to the more uniform sandy bottom at the f arfield station. Both taxa are tychoplanktonic and are thus closely associated with the substrate.
Spatial differences were also observed between intake (P2) and discharge (P5) stations for those two taxa. No station differences occurred among fish eggs or larvae. Thus, with the exception of two macrozooplankton taxa, the farfield plankton station will provide an effective spatial control when examining post-operational plankton communities for possible impacts of i Seabrook Station.
2.2.2 Pelagic Fish 2.2.2.1 Temporal By studying the six dominant species collected in gill nets, which together make up 90% of the population (Figure 2.2-5), any significant effects of plant operations on pelagic fish populations in the study area 25
i
(
TABLE 2.2-2.
SUMMARY
OF NEARFIELD/FARFIELD (P2 VS. P7) SPATIAL f DIFFERENCES IN PLANKTON COMMUNITIES AND SELECTED l SPECIES. SEABROOK BASELINE REPORT, 1987.
b
(
COHMUNITY DIFFERENCE BETWEEN P2 AND P7
{
(
Microzooplankton Community None j Selected species None q Bivalve Larvae Community None j Selected species None Macrozooplankton Community None Selected species Tychoplankters (Pontogenela inermis, Diastylls sp.) P2>P7 Ichthyoplankton Egg Community None Selected species None Ichthyoplankton Larvae Community None Selected species None l
l 26
SEASONAL VARIATION I
w 20 -
) 5 0 10 -
I 0 , , , . . . ,
l . , , , i JAN RB MAR APR MAY JUN JUL ALG SEP OCT PC/ CEC 100
} ......-
80 oeggggllI% ,
m G Atlantic menhaden
/
O pollock j 2 2
60 //// 0 Atlantic mackerel ,
O 40
- /
~
- E blueback herring E Atlanticwhiting l
' ' ~ -
E Atlantic herring w
O 20 j E O
JAN FEB MAR APR MAY JUN JUL AUG SEP CCT NW EC l
ANNUAL VARIATION 30 -
w 20 -
l S
U 10 -
0 . , , , , , , , , , , ,
1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 100 YEAR z -t' -
j ;; \ g'.,\,,,,.......- g, ,, _ ,,
m O pollock o S, O Atlantic mackerei 40 ,
E blueback herring w . ., ." E Atlantic whiting E Atlantic herring O 20 E ,
0 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 YEAR Figure 2.2-5. Seasonal and annual changes in composition and abundance of the pelagic fish community, based on catch per unit effort at gill net stations G1, G2, and G3 combined, 1976-1987. Seabrook Baseline Report, 1987.
27
(
(
should be visible. The distribution of pelagic fish varied seasonally; two I main seasonal groups of species, summer and winter, were identified from k numerical classification results (NAI 1982c). From September to April, Atlantic herring constituted from 64% to 93% of gill net catches, while in i summer months (May-August), other migratory species such as Atlantic whiting (formerly known as silver hake) and Atlantic mackerel predominated (Figure 2.2-5). Pollock (predominantly age-two fish (NAI 1985b)) is a local resident which also made up a greater proportion of the pelagic nearshore community during summer, l '
In every year, Atlantic herring was the overall dominant pelagic fish in the area; however, it exhibited large annual abundance differences that were reflected in the annual percent composition (Figure 2.2-5). When catch per unit effort (CPUE) peaked in the study area in 1980, Atlantic herring composed 82% of the total catch. From 1984 through 1987, when total ;
catches were at their lowest levels since the inception of the study, Atlantic herring constituted only 26-52% of the total catch (Figure 2.2-5).
~
Atlantic herring are known to show high variability in catches spatially as well as seasonally and annually (Bigelow and Schroeder 1953). Most of the fish collected off flampton-Seabrook were yearlings, particularly in the spring (NAI 1985b). Little is known about the habits of yearling herring, except that they seek out the warm waters of embayments in spring (Bigelow and Schroeder 1953).
Inconsistency in seasonal patterns adds to the overall variability in pelagic fish distribution. Each of the selected species.had its peak abundance during a short but distinct period of time (Figures 2.2-5 and 2.2-6). Ilowever , these seasonal fluctuations were variable among years, compounding the high annual variability, as evidenced by high coefficients of variation (approximately 150-250% for the three selected species). This was particularly important for Atlantic herring, whose abundance was the single biggest determinant of overall catch levels (Figure 2.2-5). The number of individuals that will be impinged by the plant intake would therefore be expected to vary substantially among seasons and, to a lesser extent, among 28
E - - - - -- -
1 PEAK SEASON O PEAK MONTHS ]
12 -
0 i i l
TEMPORAL VARIABILITY l
j 3-3 AMONG MONTHS (n = 12, except n = 8 fw Atlantic siheside) o AMONG YEARS (n = 12. except n = to fw Atlantic saversade)
El 5 q E
S n
< ~
O . T IE
. n i IE " I E nj O
in In ,
go . IMPO,RTANCE z -
O g 60 - O DEMERSALSPECIES(TRAWLS) m 3 ESTUARINESPECIES(SEINES) k 40 3 PELAGlcSPECIES(GILLNETS) 2 o
O 20 -
- ~
0-Y Y --- 7-- - y I
l' i
ti I
E
- 2 E
- o=
5 si o -
AI Es Ej },$ gi* IS :
w a
.=
.8 i 4 .E 2
2 P
Figure 2.2-6. Percent composition, seasonal vs. annual variability (standard deviation) of log (x+1) abundance (catch per unit effort), and months of peak abundance for selected species of fish, 1976-1987. Seabrook Baseline Report, 1987.
29
i years. Because of this high variability of pelagic fish. abundances, predict-ing abundances with high statistical precision would be difficult. s I
Since the Circulating Water System began operation in 1981, fish j entrained within the system and subsequently impinged upon the travelling screens have been collected by Seabrook Station personnel to determine !
I operational impact. During a five-month period in 1985, 970 individuals, representing 32 species, were collected from the' Circulating Water System. 1 N
These were dominated by grubby (Hyoxocephalus aenaeus, 21%), snailfishes (Liparis sp., 21%), and longhorn sculpin (Hyoxocephalus octodecemspinsus, 11%). During a seven-month period of Station operation in 1986, 1212 individ-unis representing 35 species were collected. These were dominated by grubby (21%), windowpane (Scophthalmus aquosus, 12%), and longhorn sculpin (9%).
Intermittent operation of the Circulating Water System during 1987 resulted in a total of 502 individuals representing 21 species becoming impinged upon the travelling screens. Of these, longhorn sculpin, winter flounder (Pseudopleuronecces americanus), and windowpane made up 22%, 14%, and 13%,
respectively, of those impinged. Operation of the Circulating Water System, in terms of both the number of pumps and whether the system operated at all, varied throughout the three year period. -Data obtained during full system operation will be reviewed along with these data to determine operational impacts on demersal and pelagic fish species.
2.2.2.2 Spatial Areal differences will be less important than temporal differences in evaluating potential plant effects on pelagic fishes. Because of their high degree of mobility, pelagic fish were not observed to be associated with any one habitat. As expected, relative abundances of the five most abundant taxa were very similar among stations, although catches were approximately 25% lower at the southern station G1 (NAI 1987b). Differences in the verti-cal distribution of these species may be important, however, because the intake structures are located at mid-depth, 5 m above bottom in 17 m of 30
E
}.
water. Only one of the eight most abundant species, Atlantic menhaden,'was more abundant at the intake (mid-water) depth during the months' sampled than l
at surface.or bottom (Table 2.2-3). However, this species was only'slightly l- more abundant at mid-depth, and it only accounted for 2% of the pelagic fish In the study area. Two taxa,' Atlantic whiting and pollock, were most abundant near the bottom, while Atlantic herring, mackerel and blueback herring were most abundant on the surf ace (Table' 2.2-3). These species may.
I be less vulnerable to intake effects. In 1986, for the first time'since 1980, Atlantic mackerel had highest catches in mid-depth nets (NAI 1987b),
suggesting that they could occasionally be more prone to intake effects.
These results indicated that the most abundant and frequently-occurring pelagic species did not show a preference for mid-depth distribution, verifying earlier results and the rationale for mid-water placement of the intakes (NAI 1975a).
31
i a
TABLE 2.2-3. CATCH PER UNIT EFFORT BY DEPTH FOR THE DOMINANT GILL NET SPECIES OVER ALL STATIONS AND DATES WifEN SURFACE, MID-DEPTH AND BOTTOM NETS WERE SAMPLED,1980 THROUGH 1987. SEABROOK BASELINE REPORT, 1987. <
t
(
CATCH PER UNIT EFFORT SPECIES SURFACE MID-DEPTH BOTTOM q
(
Atlantic herring 6.3 3.5 2.3 Atlantic whiting 0.2 0.6 0.8 Atlantic mackerel 0.9 0.4 0.4 Pollock 0.2 0.1 1.1 Alewife <0.1 <0.1 <0.1 Blueback herring 1.1 0.4 0.3 l
Atlantic menhaden 0.6 0.7 0.2 Rainbow smelt <0.1 <0.1 0.1 a
number per one 24-hour set of one not (surface, mid-depth or bottom) 32
l i
2.3 DISCHARGE AREA MONITORING 1
) 2.3.1 Plume Studies )
i 1
\ l 2.3.1.1 D_ischarge Plume Zone l Because the discharge plume's largest exposure will be to surface
! and near-surface waters, the primary focus in this section will be on param- )
> l eters or organisms in this part of the water column, namely phytoplankton, i l
lobster larvae, and nearfield water quality parameters. Other organisms, such as pelagic fish and ichthyoplankton will, of course, have some exposure t
to the discharge plume, but it is assumed that entrainment and/or impingement are the more important issues for these organisms.
I The water quality parameters measured showed distinct seasonal I patterns that were important in driving biological cycles. Surface and bottom temperatures reached their lowest points from January through March, then steadily increased from April to August; temperatures were generally highest from August to October before beginning their fall decline (Figures 2.3-1 and 2.3-2). Surface temperatures had a more exaggerated seasonal cycle in comparison to bottom temperatures, with higher spring and summer tempera-
.I tures. Temperatures in 1987 were average at the surface and below average at 1 the bottom. Surface temperatures peaked in July in 1987; historically they have typically peaked in August (Figure 2.3-2).
i 1
Surface dissolved oxygen had a seasonal pattern inversely related J to temperature, with peak values in late winter and lowest values in fall l (Figures 2.3-1 and 2.3-2). In 1987, seasonal patterns were similar to previous years, though November values were somewhat higber than the average.
Surface salinity values were highest in winter and lowest in spring, a result of increased runoff. In 1987, salinities were generally lower than the I
average, particularly in April (Figure 2.3-2) as a result of high precipita- 1 1
tion during that month (see Section 3.3.1). !
I 33 l
l
,i
{
PEAK ST;.ASON a PEAK MONTHS i
l TEMPORAL VARIABILIT(
20 -
5 AMONG MONTHS (n = 12) j o AMONG YEARS (n 7 to 10) 15 - .
l nO l 3 10 - irg
'y l if -
11 5- 11 I ll NO E0 .
37
. n .. 0 s i i s E E i- ig i EE i% i=E i. g go ioE ? i R 9
- : ss
- === : E g s, se si" e
isc is
.c 3 ,- Eg . & g- gg = _b a
= b b
~ ~
2t E& 3R E C 5 _s
- g E **
~
j {E go 5 2 5 $ E
} l 8 c 3 E.
Figure 2.3-1. Seasonal vs. annual variability (standard deviation) and months of peak values for temperature (*C), salinity (ppt), dissolygd oxygen (mg/1), and nutrients (pg/1). Seabrook Baseline Report, 1987. (For salinity, total phosphorus, nitrate, and ammonia values, multiply by 10.) 34
aE E
'S -
N A aN C N n R A E Yy aN V O
. ".Y T
~ .' E sT O
C e mtw aC M. d A R a E P S g y x . Y; sE O P S
- E7 O .
- ..* Vm Oi a U G
d . "
/~:. . a G
U
, A e A
- e r - L H v - L H - u - a U T J l o ' ". ' ' a U T t - N s .' J N a - N O is aUN O r . - e - a JU M D
\ M p .
- Y . '.'.* J Y
m
.- aA e .f aA e
d i c M R a .. R T P f r aP aA m o R A S u
\*., aA A
R sM
.r.
t t . M B B B . a R ' a R
. ~
s N . N A a A J J s i 0 1 s 0 2 1 0 g 0 1 1 1 G _ mE3F<Em 3r xW 3 "WA a2<EO3!2 : N A
- E
- M aE
- ~ .- -
- S' R s V
O
.- - A N N ,- E A r Yr T e ,
L : C u , Lw Ai O
, P m
E7 G aE G vm U U e oi A . aA u t r
,..X",- - .
L H T t y
' a U L H T
a r 1 N i n ' J N e !., .
. O i l
- N O P ..- .
M a t J M c Y S e
? a A Y
M c M T R a , [!!;*:I ;l:t R P f 1i t a P A r 1;1 A 8 R u !. R S A U M
.h",,.I.1*; aM a B R
N ~'
- A N
J .- J 0 s, 0 s 0 4 2 0 8 6 4 2 1 3 3 3 2 2 2 G. . g 3 r< x m n. E
- Oye3OIF mwa.ggE<'
wv
Nitrogen and phosphorus nutrients had more erratic cycles than temperature, salinity, and dissolved oxygen, but generally.had lowest levels in summer and highest in fall and winter (Figure 2.3-1). Values in 1987 followed the patterns observed in previous years except for unusually high 1 orthophosphate levels in June and July, high levels of total phosphorus'in September and October, and low levels (below detection limit) of nitrite in ( March through June. I The predictability of seasonal patterns and low year-to-year ; variability of most of the water' quality parameters (Figure 2.3-1) enhanced their suitability for impact assessment. Furthermore, they will provide information which can assist in separating netural biological variability-from impact. The phytoplankton community has shown the most seasonal and annual i variability of any species assemblage. Seasonal assemblages have changed ) rapidly and frequently, diminishing the suitability of the community for I short-term impact assessment (NAI 1985b). Some elemects of the phytoplankton community were relatively stable and predictable. For example, total phyto-plankton abundance was generally similar.among years, with a predictable I seasonal cycle that was closely tracked by biomass (chlorophyll a). Increases , in irradiance typically initiated the spring bloom, and although the species composition varied from year-to year, centric diatoms typically were among the first to appear. Densities usually diminished when nitrogen-nutrients declined and the thermocline developed. Thermal stratification prevents the replenishment of nutrients from deeper waters thereby limiting growth of spring dominants. 1986 was unusual in that there was an uncharacteristic i July peak caused by bluegreens and Leptocy1/ndricus. Phytoplankton assem-blages from 1978 to 1980 were similar, based on the predominance of Skeletonema costatum, Rhizosolenia delicatula, and Phaeocystis pouchetti, while from 1981 through 1984, only'Skeletonema costatus and Chaetoceros spp. :! were consistent dominants. In the latter half of 1986, Skeletonema continued to predominate, along with the above-mentioned bluegreens. No phytoplankton collections were made in 1987; detailed results from previout, studies are l presented in NAI 1985b and 1987b. i 36 1 l _ _ - _ - _ - - - - - _ - i
i e No spatial differences were observed in the phytoplankton community either between intake (P2) and farfield (P7) areas or between intake (P2) and discharge (PS) areas (NAI 1985b, 1987b). I' i Skeletonema costatum was chosen as the selected phytoplankton species because of its consistent predominance. Generally, there was a major i i peak in late summer or fall (Figure 2.2-2) and in some years there was also.a l smaller peak in the spring (NAI 1981f, 1982a) or winter (NAI 1980c, 1983a). 1 I Despite highly-variable peak abundances, no significant differences were. detected among years (NAI 1937b). Furthermore, intake and discharge densities were statistically similar (NAI 1987b). Simultaneous nearfield/farfield comparisons of total phytoplankton abundances and Skeletonema costatem may be the most consistent parameters for monitoring primary producers in the discharge plume area. Paralytic shellfish poisoning (PSP) levels in Myt11us edu11s, as measured by-the State of New Hampshire and Massachusetts Department of Public Health, has exceeded maximum levels allowable for human consumption every-year from 1972 through 1986, usually for a period of 1-7 weeks (NAI 1987b). In 1987, however, PSP toxicity levels in Hampton Harbor mussels were below the detection limit throughout the April-December monitoring season (NAI 1988). In 1972, toxic levels were present in Hampton Harbor for a period of 16 weeks. Although Hampton Harbor flats have been closed each summer since 1976 to soft-shell clam diggers for conservation reasons, high PSP levels caused the closure of the harbor to all bivalve shellfish digging for several 4 1' weeks each summer as well. Peak values in most years occurred in May or June, coinciding in Hampton Harbor and the farfield area, Essex, MA. The maximum value recorded since 1972 was 8398 pg PSP per 100 g meat. -l 1 Of the shellfish in the area with planktonic lifestages (Cancer I crabs, lobster, and soft-shell clam larvae), only lobster larvae Stages I-IV have strictly a surface orientation, typically found in the top few centi-i meters of water. The seasonality and variability of Cancer sp. larvae and l 1 Nya arenaria larvae were discussed in the intake area monitoring section. Successful recruitment of lobster larvae is the biggest factor.in the deter-37 l
i 1 1 l mining the level of adult lobster catches (Harding et al. 1983). Lobster larvae collected off Hampton-Seabrook actually originate from warm waters ; in the Gulf of Maine and Georges Bank (Harding et al. 1983) and are driven into the area by a combination of winds and nontidal currents (Grabe et al. 1983). Temperatures in the study area are not warm enough to allow plank-tonic development (Harding et al. 1983), reinforcing the fact that this area l 4 is probably not important in the production of lobster larvae. Lobster larvae, which were rare throughout the study area, have typically been recorded from the first week in June to the second week in October (Figure 2.2-3). In 1987, lobster larvae first appeared in early June, somewhat earlier than previous years. Maximum densities have occurred over an eight-week period between late June and late August, during the period of maximum surface temperatures. Densities of all life stages were very low, averaging
<2 per 1000 square meters (Figure 2.2-3). In 1987 densities were somewhat low in comparison to previous years. Stage I and IV larvae have predom-insted, and stage II and III were extremely rare. Densities at the farfield station (P7) were consistently higher than at the nearfield station from 1982-1987. Discharge area (P5) densities in the last half of 1986 were intermediate between the nearfield and farfield areas (NAI 1987b).
Subsurface (-3 m) " fouling" panels placed in the projected inner and outer discharge plume area and at farfield areas, show the types, timing and abundances of shallow subtidal organisms which can settle on bare sub-strates. Short-term panels, exposed for one month, estimate recruitment levels while monthly sequential panels, exposed for 1-12 months (Figure 2.3-3), show the development of the fouling community. Biomass, density, and number of species showed patterns that were highly consistent from year-to-year and between nearf'ield and farfield areas, reflecting the increase in settling activity in summer and fall. The individual macroinvertebrate taxa also had a predictable seasonal pattern. Only a few showed heavy recruitment before June (Balanus sp. In April and Elece11a sp. in early summer). In 1987, the overall patterns were similar to previous years, although biomass on September short-term pannis was much higher than in most past years. Surface panels should prove to be an effective monitoring tool for benthic settlement activity, particularly when compared to farfield stations. 38
$7A?!0N 4 $9AT!0N 19 J
J fQAN JJA 80ND J FM ANJJA50N0 nrunene tw2 ......
........ E EUUE Nruiioa, 1982 ...... ...... gamma i
- i,83 ...... _ ...mmmEE 15 *- --
M ) igg 4 _ . . . . . . RE 1984 - ~ - m i986 8 , 1986' M i987 -" gEEa@ 3987 "
"*-MM[E*a a
-aaaaa" Biatelia sp. 1982 .a ~~~~~.~~~.naa Blatella sp. 1982 ~
im ... ......g........~.. im . . . . . . . . . . . .g. . .g im __.................. im .........E E E im a a M Q ((Q 3986' EEETWETH im' _ ......g............ im _ _ ...g............... ) g j Lassa falcata 1982 .aa M W Lassa faicata 1982 a.
.aa.NEI0a E im . . . _.........g im ......H515mD im ..._...E m im H MTP im' _ im* _ . . .
1987 . . .M i987 a.a.a*.' },lT[E Nudibranchia i982 naan.a. .a intIhranchia 1982 .aa g." "* aaaaaaaaa"* 1983 "*aaaa"" - i983
- a. ~~a 1984 a. .~- aa. ~
i384 8 ~~~*a i986' *a aaaaaa i986 a aaa a"* a *" im "*anea."" i987 Tubularia sp. i982 eaa. Tubularia sp. 1982 a gHaQ im ... g 3 ...... im ...g...... im _ . . . . . . im ......g... a a iw ...... iw im m... ~ ~~ 15 NE E - Obella sp. i982 a EUM otetta sp. iS82 Ra EM an im _gE * - im - E-im _ ...g a n a_g.a im a._ g ana.a a. iw i gg . . . . . . . . . . . . im a g__. . . _ iw . . . m. . . . . iw -gg.. .g. . . . . .
.a ana." a. Balanus sp. i982 ........................
Balanus sp. i982 i983 ......gtst...g...... im .. . . ..g g. . .g.. .. . . im ___......__......_...... im . . . . . . . . . 3...g. . . iw a _............... iw i
. . .g- a a a u n i987 **EETIMaaaE3 ,
1987 EaaaEIDUMMID
*a aa" Ne;'is sp. 1982 *aa aaaaa Nereis sp. i962 i9g3 ..................... i983 .....................
- *aaaaa 1954 "waa-1984 8 ****+++=*- -
1%6 * * - - ' ' ' * * * - - i986' i9g1 ..................... igg 7 _.a aa a a a a a. Poiynoidae i382 l[Q ". *a olynnidae 19A2 *aa. aaaan.aa i9g3 .. ... igg 3 . . . . . . _ lW *"-""*"a-"- 1984 ig a .._"a* .....******* i986 8 ana~""*"
,I 1. .. im .....
- present a. 25% frwyney 5 267s E 16 ion !
l
'No fouling panels placed or collected from January 1985 througt. June 1986. l l
l Figure 2. 3-2,. Annual settlement periods, abundance and survival of 4 l major taxa based on examination of sequentially-exposed l panels at nearfield Stations 4 and 19. Seabrook i Baseline Report, 1987. l 39
2.3.1.2 Intertidal / Shallow Subtidal Zone ' An area outside of the immediate surface plume area that is being , monitored for potential plume effects is Sunk Rocks. Intertidal (MSL and MLW) and shallow subtidal (-4.6 m) stations which are representative of the area were monitored on Outer Sunk Rocks (nearfield) and at Rye Ledge (farfield). Benthic algae and macroinvertebrate collections taken annually (August) at Stations 1MLW and SMLW (intertidc1) and Stations 17 and 35 (shallow subtidal) exhibited species assemblages that were consistent and highly similar from year to year at each station (Figure 2.3-4). Each annual collection at a station was grouped (by discriminant analysis) with the majority of those collected in other years at the same station (Sections 3.3.2 and 3.3.3). In 1987, macrofaunel and macroalgal collections were similar to those in previous years (the same species assemblages that were present at each station in previous years were found in 1987). The assemblages identified by this analysis were s*.rongly related to the depths of the stations, particularly for the algae, which exhibited a neticeable difference among depths in which species dominated the algal community (Figure 2.3-5). Colonial macrofaunal assemblages were somewhat less predictable from year-to-year (NAI 1985b). Intertidal colonial assemblages were distinct in their species composition, but those from shallow subtidal areas in most years were similar to those from mid-depth areas. In several years, assem-blages of colonial macrofaunal species were unique and unrelated to any other assemblages. l Fourteen benthic species were selected for more intensive moni-toring because of their trophic position, abundance and commercial or recreational value (Table 2.3-1). Parameters monitored included abund-ance (all taxa), size (fauna only), and reproduction (epibenthic crusta-ceans). All life stages of the commercially-important species were studied. Some of those taxa were monitored in the Sunk Rocks area while others were examined as part of the discharge or estuarine studies. 40
I m 25 - DEPTH OCCURANCE g 20 - O INTERTIDAL (STA.1MLW, SMi.W) O SHALLOW (STA.17,35) 4 u) E uiO-DEPTH (STA. 16,19,31) 15 - ~,s. - 3 DEEP (STA.13,4,34) ggKig cr: 10 - [ 5- f - \ 5 $$l$N$
- r---
0 i 6 5 4 3 2 1 ! ALGAE SPECIES ASSEMBLAGE I 1400< gg ABUNDANCE m 1000'
$ 800'
$ 600<
E 400< 200* O Y-6 5 4 3 2 1 ALGAU SPECIES ASSEMBLAGE 25 - DEPTH OCCURANCE g N 20 - $:l@dh O INTERT10AL(STA.1MLW,5MLW) 2 agsr! g O SHALLOW (STA.17,35)
< M
#@sd;(% 3 MIO.0EPTH(STA. 16,19,31)
M 15 - ln$ DEEP (STA.13,4,34) O E k!$hki 0 -i 6 5 3 1 2 4 BENTHIC SPECIES ASSEMBLAGE 1000 1 ' ABUNDANCE g 100 -l B t Figure 2.3-4. 6 M .5 3 1 BENTHtC SPECIES ASSEMBLAGE s- 2 4 Depth and abundance characterizations of species assemblages identified by discriminant analysis of August collections of algae (g/m' of dominant taxa) and marine benthos (thousands per m 2 of dominant taxa) during 1978-1987, Seabrook Baseline Report, 1967. 41
100 - - b NNs >>>>', ssss
U ists.
////w <g/
$/ / /,y
/ ///e !/ /// i
/ / / / - # ##//
80 - W sys. A- ww i,ssif
/# # # ,
//J # /) ,
tssss ff##/ WW w a,- D OtherTaxa w
'/ y/,N 1
>>>X- O Ptilota serrata !
! 60 -
',I'lO,!'l l
E WW j m e' Q' E Phyllophora spp. ' O Qs>y] , /,w/ g o W W>'
/////
B Corallinaofficinalis l A ///// w ,' ,W, o 40 - ,;,s,;,;, E Phycodrys rubens g - wse
- a. %+x D2'lY
/////
E Chondruscrispus wy
'4W(
h,sX ssss-E Mastocarpus stellatus 20 - l l l l 0
/ 4.6 9.0 11.6 18.3 19.7 MEAN DEPTH (m)
Figure 2.3-5. Percent composition (based on biomass) by depth strata for dominant macroalgae species at marine benthic stations in August, 1978-1987. Seabrook Baseline Report, 1987. 42 l
1 I i TABLE 2.3-1. SELECTED BENTHIC SPECIES AND RATIONALE FOR SELECTION. ) SEABROOK BASELINE REPORT, 1987. 8 SPECIES (COMMON NAME) LIFESTAGE RATIONALE l Macroalgae Laminarla saccharina A Habitat (canopy)-forming primary (kelp) producer i Chondrus crispus A Habitat (understory)-forming l (Irish moss) primary producer; sporelings may be heat sensitive l Benthic Invertebrates l Ampithoe rubricata J,A Intertidal / shallow subtidal (amphipod) community dominant Jassa Is1cato J,A Intertidal / shallow subtidal I (amphipod) ' community dominant Pontogenela inermis J,A Subtidal, ubiquitous community l (amphipod) dominant l Nucella lapillus J,A A major intertidal predator of (dog welk) Hytilus edu11s Asteriidae J Predator, community dominant (starfish) Strongylocontrotus J,A Potentially destructive droebrachlensis herbivore (green sea urchin) Dominant Bivalves Hyci1us edu11s L,S,A Habitat former; spat may be heat (blue mussel) sensitive Mya arenaria L,S,A Recreational estuarine species; (soft-shell clam) larvae entrainable Ep1 benthic Crustaceans Carcinus maenas L,A A major predator of soft-shell (green crab) clam spat Cancer borealls L,J,A Important predator and prey. (Jonah crab) Cancer 1rroratus L,J,A Important predator and prey ; (rock crab) Nomarus americanus L,J,A Commercial species; larvae plume (American lobster) entrainable a A = adult; J = Juvenile; L = Larvae; S = Spat 43
{ J Algal selected species had highly. consistent biomass.or' abundance. levels among years, with differenaus between nearfield and farfield stations observed in the. shallow subtidal but not the intertidal. The algal dominant .i Chondrus crispus had' low annual variability, with no significant differences in biomass among years from 1982-1987 in the intertidal zone and 1978-1987 in the shallow subtidal zone (Table 2.3-2). Intertidal biomass values of ( , Chondrus were significantly different between nearfield and farfield areas in both the intertidal' zone and the shallow subtidal zone (Figure 2.3-6, Table 2.3-2). Densities of the dominant kelp, Laminaria saccharina showed no ; differences among years or between nearfield/farfield stations in the shallow I subtidal (Figure 2.3-6,. Table 2.3-2). Spatial heterogeneity and variations in recruitment success caused i a high degree of variability in abundance of macrofaunal taxa (Figure 2.3-6).
]
Significant differences in annual abundance were found among years for most j of the taxa, and nearfield and farfield stations were almost always signifi- j cantly different (Table 2.3-2). For these species, impact assessment will be ! I icost effective when the preoperational period is compared to the operational period within a given station. Few differences in the historically-observed trends were noted in 1987. The amphipod Ampichoe rubricata, once one of the i intertidal dominants, continued its steady decline in abundance first noticed i in 1982; in 1987, no A. rubr/cata were collected at eith r intertidal station l (1MLW or 5MLW). Abundances of other taxa were within the range of previous. j years. l Length measurements of macroinvertebrates were a more stable and predictable parameter. In most cases, annual mean lengths were statistically similar among years and between stations. Specimens of the gastropod Nucella lapillus were unusually large compared to previous years at the nearfield station (1MLW), but they were smaller than usual at the farfield station (SMLW) . Sea stars (Asteriidae) were smaller in 1987 than in any of the previous five years when measurements were recorded, indicating successful recruitment of young-of-the-year. 44 1 l-
L l i l j TABLE 2.3-2.
SUMMARY
OF SIMILARITIES" IN ABUNDANCE, BIOMASS, j FREQUENCY, OR LENGTH AMONG YEARS AND BETWEEN STATIONS , I FOR SELECTED MACROFAUNAL AND MACROALGAL SPECIES AT IRTERTIDAL /ND SHALLOW SUBTIDAL DEPTHS. SEABROOK BASELINE REPORT, 1987, 1 i AMONG YEARS I NEARFIELD VS. l FARFIELD SIMILAR DISSIMILAR Similar Nucc11a lapillus (L) Ampithoe rubricata (L) Jossa falcata (shallow Mytilidae (shallow sub-subtidal, panels) (L) tidal panels) (A) l
'l Mytilidae (MLW, shallow Mytilidae (panels)(L) I tidal)(L)
Laminarla saccharina (A) Jassa falcata (panels) (A) j Dissimilar Asteriidae (L) Jassa falcata (shallow subtidal) (A) Chandrus crispus (B) Ampithoc rubricata (A) (MIM, shallow subtidal) Nucella lapillus (h) Aster 11dae (A) Myt111dae (MLW) (A) e Results from ANOVAs, paired t-tests, or Wilcoxon's summed ranks tests (A) = abundance (L) = length (B) = biomass 45
l TEMPORAL AND SPATIAL VARIABILITY a AMONG YEARS,NEARFIELD (n 10 except n 9 for Laminaria, and n 7 for Asteriidae) O~ o AMONG YEARS, FAPFIELD (n - u) - 5- { w 4-O - z .. II
- O II 1 E
I[ y g - 3- - m n .. o
<c 8:
2-II 1-
*I I
..o 0
1 80 - IMPORTANCE 2 o 60 - J E E Shallow subtidal j m E Intertidal 2 40 - 2 O 1 U 20 - j Y i N/A N/A N/A o i i "P"' T ""f'" g te
.= s_
3 22; a
=
s s e me=
=4=
3= 5%g 52 28 oo . ti
-a 2_
== v %. 42 2^
z, ; Es E! "" 55 - SE .$ m* En In 15 "Ei% 25 CE i ~n E 5e *E 2 35 E = 2 2 2 o 6 gg g 3 Figure 2.3-6. Percent composition and nearfield (Sta. 1MLW & 17) vs. l farfield (Sta. SMLW & 35) annual variability (standard deviation) of log (x+1) abundance for selected intertidal and shallow subtidal species of algae and benthos. Seabrook Baseline Report, 1987. Abundance is No./m 8 4 except for Chondrus, which is g/m . 8 46 J
I l L-i ( 2.3.1.3 Estuarine Zone 1 h Environmental studies in llampton 1[ arbor estuary include monitoring physical parameters (temperature and salinity), fish populations, benthic d j macrofauna, and juvenile and adult soft-shell clams (#ra arenarla). One of
]'
the main environmental issues in the 11ampton-Seabrook estuary related to
~
L plant operation is whether the offshore intake and discharge will' impact the , t l adult clam population in llampton Harbor. The probability of impact from the l most-likely source, entrainment of Nya larvee, i.s small (NAI 1977e); this is. ] discussed in Section 2.2.2. Natural variability cf Jnvenile and adult Nya arenaria will be discussed in this section. i Temperature and salinity, monitored'in Hamptor: liarbor and Brown's River since 1978, provide valuable information for interpreting biological phenomena. Maximum temperatures usually occurred in August, with minima in 1 January or February (Figure 2.3-7); 1987 was no exception to this pattern. ] Salinity levels had a less distinct seasonal cycle than temperatures, but were usually lowest in spring, coincident with increased runoff. This was particularly true in April of 1987, when heavy rainfall, in addition to melting snow, caused severe flooding in New llampshire and Maine. In Brown's 1 River, average annual salinity values remained high for a three-year period from 1980-1982, coinciding with low precipitation and highest discharge volumes from the settling basin. This was the period when the maximum dewatering of the cooling tunnels took place, and the salinity of the settling pond's discharge water was relatively high. Salinity levels dropped, with fewer fluctuations, from 1983-1987, when discharge volumes l decreased and precipitation returned to pre-1980 levels.- Hampton liarbor salinities, which were not as susceptible to these influences because of the influx cf a large volume of offshore waters, showed higher salinity and lower
. year-to-year variability than Brown's hiver. j 4
1 The benthic macrofaunal community in Mill Creek (Station 9) and Brown's River 18tation 3) was typical of New England estuaries. The species ; composition was also consistent with that from other estuaries on the East ! Coast (McCall 1977; Watling 1975; Santos and Simon 1980; Whitlatch 1977). 47 i
-i
25 - Temperature
....~.,
20 - l . o - w 15 - / e ., . o . . n
@ 10 -
- m m - '.
r . .. .. , 5- OVERAU.MEAN
... .. 1887
. "/
0 , , , , , , , , i i i JAN FT:B MAR APR MAY JUN JUL AUG SEP CCT NCV CEC MONTH 30 - Salinity 25 - .
/ ..
f,,. p' q-'.......
~ .
%g.
- 20 - .- .
g ' Xy .....- t-15 - z 3 ,
< 10 -
m - OVERALL MEAN
. . . . . . . 1967 5-0 , , , , , , , , , , , ,
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT PC/ CEC MONTH I Figure 2.3-7. Mean monthly seawater surface temperature and salinity with 95% confidence limits taken at low tide in Brown's . River (Sta. 3) in 1987 and over the entire study period I (May 1979 - December 1987). Seabrook Baseline Report, ; l 1987. l l I 48 l
l l Surface and subsurface deposit feeders predominated, including opportunistic polychaetes such as Streblonplo benedict 1 and Capitella capitara, with l suspension feeders and omnivores forming an important component (NAI 1985b). l The most numerous species inhabiting estuaries are those which are resistant and resilient to the natural changes in the physical environment, such as fluctuating temperature, salinity, dissolved oxygen, and sediment grain size. In Mill Creek and Brown's River, the biological parameters measured were highly variable seasonally and annually whir.h is typical of this physically heterogeneous habitat; total density, numbers of taxa, and all of the dominant species tested showed significant differences among years and between stations. Some of this variability was related to changes in salin-ity. The combination of lower precipitation and higher levels of discharge from the settling basin from 1980 to 1982 apparently caused higher and less-variable salinities in Brown's River. At the same time, total abundance and number of taxa increased (Figure 2.3-8), along with densities of Stroblosplo benodlcti and Capite11a capitata at that site. Higher salinity levels probably enhanced the habitat for more stenohaline species, and at the same time, opportunistic polychaetes invaded the changing habitat. Following an increase in precipitation and decrease in discharge volumes, these param-eters dropped to their lowest point in 1984; however, they had returned to pre-1980 levels by 1987. Important estuarine fish include both diadromous species as well as residents. Three anadromous fish pass into the estuary: rainbow smelt in winter and alewives and blueback herring (" river herring") in spring, travelling to upper reaches of local rivers to spawn. Rainbow smelt were caught at the entrance to the estuary (Station T2) from December through March or April (see adult fish section 3.2.2). Abundances were significantly different among years, causing moderate baseline variability, making the detection of minor population changes unlikely. In spring and summer, sparse and erratic numbers of young-of-the-year and yearling smelt have been caught in beach seines (Figure 2.3-9), but no one age group (based on length-frequency) has been consistently dominant (NAI 1985b). Rainbow smelt have 49
ESTUARINE BENTHOS j 10000 - - 50 i 8000 - '"'....... -40 1 a ,q p 6000 - . j .
., - 30 l-
- u. _1 H .
m . .
. l '.
' Oi )
Z */ g <
$ 4000 - -20 g 2 i c
z 3 2000 - DENStrY ,
-10
.-. .. NUMBER OF TAXA ,
0 , , , , , , , , , 0 1978 1979 1980 1981 1982 1983 1984 1986 1987 YEAR l SALINITY 32 - l 30 -
)
i
$ 28 -
c. 26 - . na data 24 , , , , , , , , , j 1978 1979 1980' 1981 1982 1983 1984 1986 1987 ) YEAR 3 1 Figure 2.3 8. Annual geometric mean density (No/m2) and mean number of taxa per station of estuarine benthos. and annual mean salinity, at Browns J River and Hampton Harbor. Seabrook Basel^ u e Report,1987. No data ] were collected in 1985. 50 __ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ h
SEASONAL VARIATION 400 - y 200 -
- n. !
o O , , , , , , , , l } JUL CCT fC/ l } APR MAY JUN AUG SEP 1 100
, , , a****woorers,ss---- -
h 80 % , l j 5 %g ,e Q winterflounder l k .
,,e' / O Atiantic herring
( 2 s ,,** G rairbow smet i
~
g posock l O - 40
) 3 Fundulus sp. l g .
z 3 Atlanticsaverside l w 1 0 m 20
.3 7
APR MAY JUN JUL AUG SEP CCT PC/ ANNUAL VARIATION j 400 - j w
@ 200 -
o i 0 , , , , , , , , , , j 1978 1977 1978 1979 1980 1981 1982 1983 1984 1987 YEAR 100 ,.. ...._ 80 <v w ( __ s ; o me,,_e, ! 60 {, , O Anance herring o ' - - O raintzw smett 40 EW y 3 Fundulus sp, W % E Atlantic silverside
@ 20 w "%~t . .
Q. , 0 1978 1977 1978 1979 1980 1981 1982 1983 1984 1987 YEAR Figure 2.3-9. Seasonal and annual changes in composition and abundance of the estuarine fish community, based on catch per unit effort at beach seine stations S1, S2 and S3 combined 1976-1984'and 1987. Seabrook Baseline Report, 1987. 51
never comprised a substantial portion of annual seine catches, and over all years (1976-1984 and 1987) averaged only 3% of the total catch. Data were not collected in 1985 and part of 1986. Catches in 1987 (April through November) were lower than average. River herring, which includes alewife and blueback herring, were monitored both in the Taylor River and in Hampton Harbor from 1980 to 1984. The size and length of the river herring "run" was shown to be variable, with the number of days that fish were observed passing the Taylor River ladder ranging from 31 (1982) to 47 (1981) (NAI 1985b). New Hampshire Fish and Game has estimated run totals to range from 94,000 (1981) to 205,000 (1980) during the 1978-84 period (NAI 1985b). Their staff removed fish from the ladder during peak periods to stock other water bodies. Changes in the run size were affected by year class strength. Periodicity of the run was affected by water temperature and level which were in turn influenced by rainfall and the resulting runoff. Alewives and bluebacks were the third most abundant species caught in beach seines in the Browns River (S2) and Hampton River (S1), respectively (Figure 2.3-10); however, this was caused by large but infrequent catches at these stations. In the estuary as a whole, these species constituted only about 6% of the total catch (1978-1987). Another species which uses the estuary is winter flounder. This species undergoes onshore / offshore migration, depending on the time of year (Bigelow and Schroeder 1953). Juveniles (age one and two, based on length-frequency analysis) were the main constituent in the estuary, primarily collected during the spring and summer (NAI 1985b). Recruitment was evident by the occurrence of young-of-the-year size classes. Total catches were somewhat variable, and catches in 1987 were much lower than average in all months but June and August (see Section 3.2.2). The dominant resident species in the estuary was Atlantic silver-side, which typically comprised 67% of seine catches during the baseline period (1976-1987) and 90% within their abundant period, August to November 1 (Figure 2.3-9). The population was composed primarily of yearling fish but l the occurrence of young-of-the-year size classes in spring indicated recruit-52
100]
- . ey
- ssp W s's's 4
O others 80 - O blueback herring l E rainbow smelt y 60 -- G Atlantic herring E 8 g O American sand lance O O E alewife o
@ 40 -
c. E pollock E mummichog 20 E Atlantic silverside O S1 S2 S3 STATION Figure 2.3-10. Percent composition by station for abundant species of fish collected in beach seines, all years combined, 1976-1984 and 1987. Seabrook Baseline Report, 1987. 53
ment (NAI 1985b). Variability in total seine catch has been the result of f i high variability in catches of Atlantic silverside; catches were high from 1976-1981 (200-360 fish / haul) and much lower from 1982 - 1987 (60-100 fish /- ) I haul) (Figure 2.3-9). Since the Hampton-Scabrook estuary contains the majority of New Hampshire's stock of the recreationally-important species, Nya arenarla, an extensive sampling program (over 13 years) was undertaken in order to f characterize the natural variability in densities of all lifestages. Of the potential impact types, larval stages will be most susceptible to intake effects and therefore are discussed in that section (Section 2.2.1). Spat settlement densities appear to bear no relationship to the abundance or periodicity of Nya larvae in the nearshore waters (NAI 1982c). It would appear that Nya veliger behavior (i.e. their " readiness" or competency to settle) combined with the timing of favorable currents may be more important to settlement success than sheer numbers of larvao in the water column. Such conditions apparently existed in 1976, 1977, 1980, 1981 and 1984 when young of-the-year spat densities were highest at flat 1 (Figure 2.3-11) and other flats. The 1976 year class in particular provided an important and rejuvenating recruitment to the local population as shown by the high den-sities of 13-25 mm clams in 1977 and 1978 (Figure 2.3-11). Continued low densities of spat from 1983 through 1987 at flat 1 (Figure 2.3-11) and other flats suggest that the standing crop of adults will remain low for at least another three to four years. Once settled, survival of young-of-the year Nya depends on both the level of predation from its two main predators, the green crab and human clam diggers, and the absence of diseases such as neoplasia. Despite relatively heavy densities of young-of-the year in 1980, 1981, and 1984 on Flat 1, recruitment to yearling clams was minimal (Figure 2.3-11). This pattern was replicated throughout the estuary. Predation by green crabs, whose densities began to increase in 1980 and from 1983-1987 remained much higher than previous years, may have virtually eliminated the first and second year-class. Human predation is also an importent factor in the level of harves-54
i' l y i 3,g , FLAT 1 YOUNG- OF-YEAR (1 - 5 mm) 2.5 -
~> .
>=>
- E O' 2.0 - ..
- b l 8 -
f pE 1.5 - oD .. xo@' o o f - " g 1.0 - u o w o a n. . 1 o - 0.5 -
.. . o- " $I $ l t
n 0.0 , , , , , , , , , , .. r i , 74 75 78 77 '78 79 80 81 82 83 84 85 86. 87 YEAR SPAT (13 - 25 mm) 2.0 - ..
$g 1.5 -
58 5m . Ow OE oo 1.0 - MO .
~@
85 O.5 -
" . r r ., r, T, 0.0 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 YEAR.
' I Figure 2.3-11. Annual means and 95% confidence limits of densities:
(No./ft') of Mya arenarla young-of-the-year and spat in Hampton-Seabrook on Flat 1. Seabrook Baseline Report, 1987. 55
i 1
-table clams, causing mortality to adults as well as spat and juveniles by '(
disturbance Digging activity has declined sharply from 1982 t'o 1985 with'a I small increase in 1986 as clam diggers switched to other flats in an effort ; to harvest clams. Digging activity resumed its decline in 1987 (Figure 2.3-12). The standing stock has declined precipitously since 1983, lagging . trends.in digging activity by one-year (Figure'2.3-12). Finally, the pres- -) ence of disease may add t'o the effects of predation. Neoplasia, a cell growth disease fatal to Nya, has been detected in 3-27% of the Nya from Hampton Harbor flats'1 and 2; no incidence of this disease was found at flat 4 (Hillman 1986,.1987). , i The ability to assess impact in adult clams in Hampton estuary will depend on close monitoring of all of the factors important to recruitment and predation. Clam seeding by the State of New Hampshire during 1987 in tidal creeks running into Hampton Harbor may enhance spat densities, but the ultimate effect on harvestable clams depends on predation levels and disease, t 2.3.2 Benthic Monitoring 2.3.2.1 Ma_croalgae and Macrofauna ( Monitoring of the benthic organisms (macroinvertebrates, algae, demersal fish, and epibenthic crustaceans) was established to determine the 4 extent' of change (if any) to the community structure in this zone as a result of plant operation. Changes could be manifested by (1) the enhancement of detritivores and suspension feeders, (2) the increased attraction of benthic-feeders caused by locally-increased food supply, and/or (3) impact on organisms sensitive to the increased detritus resulting from moribund entrained organisms. Mid-depth and deep (10-20 m) benthic communities, including macro-algae, macrofauna, and bottom panels, were sampled to monitor the preopera-tional benthic community Year-to-year variations in community structure 56
--__---._7 1
)- -! .. 'I l N
... .. UCENSES )
-15000 - 1
) i i' l y . i . . .... ... ..*..', .* .
* ,s
\
, \
b 10000 - \.
\
\, :
!'f**....,'".....
'W '
o .
..g 3 *
. ?*., \
\
~.
,/.., i J
- f. . .' . .
w .
\. !
/ ..
l .* '.. 5000 - '.
.I '
m '. i'
' \'*.,'...,,**
-\. '\
1
.\
0 ' , , i ' ' ' . ' 3f7g 1973 197' I$ 96 1977 I'T$ 1 62 1983 i $* YEAR Figure 2.3-12. Number of adult clam licenses issued and the adult i clam standing crop (bushels), Hampton-Seabrook ! Harbor, 1971-1987. Seabrook Baseline Report, 1987. i i 1 1 I 5 57 ,
were small in comparison to variations related to depth and substrate. The macroalgae community was highly similar among years, although less so than in the intertidal and shallow subtidal areas. Species composition of sample collections in the mid-depth and deep subtidal areas during 1987 were similar to those taken at the same station in previous years (Figure 2.3-4 and Section 3.3.2). The same was true for macrofauna, where all collections at the six mid-depth and deep stations had species assemblages which resembled those in previous years (Figure 2.3-4 and Section 3.3.3). Colonial macro-faunal assemblages in the mid-depth and deep areas differed from year-to-year, and did not show a distinct association with depth (NAI 1985b). Patterns in abundance and size distribution in selected benthic species were only slightly less predictable than species assemblage charac-teristics. The green sea urchin and the amphipod Pontogenela inermis did not vary significantly in abundance among years, but mussels (Mytilidae) did (Table 2.3-3). There was relatively low variance in abundance among years for most of the species (Figure 2.3-13), compared to some of the more vari-able communities such as zooplankton and ichthyoplankton. Length measure-ments were a stable parameter; no differences among years were detected (Table 2.3-3). Few nearfield/farfield differences were noted in the mid-depth / deep j region. In the macrofaunal and macroalgae community, all farfield stations were more similar to their nearfield counterparts than any other areas, , indicating their suitability as " control" areas (NAI 1987b). Collections made in 1987 in all cases were most similar to the majority of collections from previous years at the same depth stratum (Figure 2.3-4). Most nearfield annual abundances and all nearfield lengths were statistically similar to those from the farfield area (Table 2.3-3). The only irregularity in spatial distributions was in the macroalgae and macrofaunal community structure at mid-depth Station 16, which was more similar to shallow subtidal stations < than those in its own depth zone. The predominance of algae-covered ledge at ; this station caused . increased amounts of algae and correspondingly higher abundances of herbivores. l l 58 t
) a TABLE 2.3-3.
SUMMARY
OF SIMILARITIES IN ABUNDANCE OR LENGTH AMONG YEARS AND BETWEEN STATIONS FOR SELECTED SPECIES IN THE MID-DEPTH ZONE. SEABROOK BASELINE REPORT, 1987. l k AMONG YEARS NEARFIELD VS. FARFIELD SIMILAR DISSIMILAR Similar S. droebachtensis (A, L) Jonah crab Pontogenela inermis (L) hodlolus modlolus Mytilidae (L) Dissimilar Pontogenela inermis (A) Rock crab Lobster Winter flounder Hakes Yellowtail flounder Rainbow smelt Atlantic cod Mytilidae (A)
) "Results of ANOVAs, paired t-tests, or Wilcoxon's summed ranks tests.
Abundance or catch unless otherwise noted. (L) = length (A) = abundance I 59 __-__-__a
- a. h8 <Tg $5b Y a g13 e e k rg5'k~
E C N A D u. N mo H e t H U H B A o. t anu G O L m o
) )
r s)r s ) r e o u r t t ime t os e e o t e r t em ee r ie s lum nm n nm t e o i d i ot e ig e d e s e ch e ty a r ora ie r oc r Muq muq n a lybe eu s s e g uq ge q s u o Js n roe J J lo od o r o N i 5 d tno t
.N(
( o2 P(oN S M0J o N( [TO2 hm N . O I T I S O P 8 M O . C T N o. E C R . E P 3> o ' ' ' -
) ) s r
e r e is) r u ) r t t me t ost e e s e r t ee r i s e om e lum Inm t n nm d io ei e l e d e ch e il t ye r ora Me e r ocr a muq lybe u Muq n a e uq s geq e u -s g nos _ J t o o sJ od r J o _ o l 5 t no r N d t N _ ( o2 oN P( S ( M0J _ o N( - m TneJ r hU meygn o rg3"r" ou $" ue17g n.Cd 4 wc <". mm M M ntg- w.v .- $" <m dwr4 ^ gDomn Oo< 2n omv OH _ n x+, v =&ca.$Q %on 5 eon 1 &D 0eTd *OaD - . O aOoo _ ne y* ema - ' m* oo ne$e~E yjoNM* wem4-o (t'
f I Because of apparent year-to-year stability in the annual community structure demonstrated above, the once per-year August sampling provides a i I good baseline for monitoring potential changes in total numbers of taxa or l ! individuals. Community structure analysis provides a simultaneous view of ,
# )
species numbers, abundance, diversity and dominance, and if changes occur at 1 a particular place or time. Results also indicate that certain species in the study area, because their abundance or size patterns, are predictable and ) changes, if they occur, could be evaluated with these taxa. 2.3.2.2 Demersal Fish ) Demersal fish which inhabit or feed in the discharge area are important not only because of their predominance in the food chain but also because of their commercial value. Six taxa comprised close to 80% of total otter trawl catches both across months and years (Figure 2.3-14). Effects, or lack thereof, should be evident from following the distribution of these 4 i six taxa, although the total number of taxa as well as rare and infrequently- 1 i occurring species have also been monitored. Numerical classification of I 1978-1982 data identified two basic seasonal groups: " winter" (December- l March) and an extended " summer" period (April-November) (NA1 1983b). These ) ) two periods were evident from monthly relative abundances (Figure 2.3-14) which show rainbow smelt were prominent mainly in winter, and hakes (red, 4 white and spotted) and longhorn sculpin composed a greater proportion of the demersal population in summer. The overall com.uunity dominants, yellowtail l and winter flounder, provided some temporal stability to this demersal community (Figure 2.3-14). Long-term trends were also evident; total catches j were highest in 1980 and 1981 when catch per unit effort was'almost twice as high as the CPUE in 1977 and 1985 (Figure 2.3-14), the two lowest years. Total catches steadily declined from 1981 through 1985, then increased slightly in 1986 and 1987. Variations in catch from year to year are lower than seasonal variations (Figure 2.2-6), even for winter flounder, which usually doesn't show a strong seasonal peak. Longhorn sculpin once accounted for an much as 27% of the total catch in 1984, but in 1986 and 1987 accounted for less than 10% (Figure 2.3-14). 61
r 100 - SEASONAL VARIATION w ko 50 - r 0 . . . . . . . . . . . . JAN EB MAR APR MAY JUN JUL AUG SEP OCT FO/ TC 100< Z O - P 80 < " in O Q rainbow smet g 60 " O Asiante cod O El wrnwtioundw . O E * *" 40
- g hakee g 3 yellowtailflounder y
g 20 < E O- < JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NG/ OEC ANNUAL VARIATION < 100 -
< I I
w
@ 50 - #
0 . . . . . . . . . . . . 76 77 78 79 80 81 82 83 84 85 86 87 100 - 2 80 - W ' Q rairnowsmet 2 60 - O Allante cod g winterflounder o E longnom aculpin 40 - g .m y < g yellowtailflounder S 20 - t . 0-7,6 77 78 79 80 81 82 83 84 85 86 87 YEAR Figure 2.3-14. Seasonal and annual changes in composition and abundance of the demersal fish community, based on catch per unit effort at otter trawl stations T1, T2 and T3 combined, 1976-1987. Seabrook Baseline Report, 1987. 62
1 I The age structure of the fish populations is also a factor con- ) tributing to abundance variability. Based en 1983 and 1984 length-frequency data and age-size information from the literature, the dominant age group / collected at the nearfield trawl station (T2) was as follows: RECRUITMENT SPECIES DOMINANT AGE GROUP EVIDEfff? a Atlantic cod Age one and two yes Hakes Several yes , Yellowtail flounder Young-of-the-year yes ; Winter flounder Several yes Rainbow smelt Young-of-the-year yes ) "From presence of young-of-the-year or yearlings during certain seasons (NAI 1985b) As with most of the fish sampled in this study, the majority of fish col-1ected with otter trawls were juveniles. Only hakes and winter flounder had no one age class dominant, although presence of young-of-the-year for these ) as well as the other taxa indicated the timing of recruitment. Spatial differences are another important consideration with ) demersal fish. Farfield stations T1 and T3 were similar in overall catch per unit effort and relatively similar in species percent composition, although the relative contribution of sculpins and yellowtail flounder was reversed at the two stations (Figure 2.3-15). The nearfield station was most unique, with total CPUE (averaged over all years) being 40% lower than at farfield sta-tions. This station also had a noticeable number of dates on which samples could not be collected due to the presence of commercial lobster traps. While CPUE calculations take this into account, the unavailability of data during certain fall months has likely affected catch statistics. Winter flounder and rainbow smalt (together) comprised 43% of the overall catch at T2, compared with 8-11% at the farfield stations. Most of the differences in total catch and species composition can be attributabic to local habitat differences. T1 has a sandy bottom, T3 has sand mixed with cobble and shell 63
I t 100 - O others E pcilock iam,,,,,, E skates { E Atlantic cod I D rainbow smelt
- u .
E winterflounder
~
E longhorn sculpin
, E hakos E yellowtailflounder 20 -
T1 T2 T3 STATION s col ot rt s, 1 o n 1976-1987. Seabrook Baseline Report, 1987. 64
l ) debris,'and T2, althcugh mainly sand, has high currents, often resulting in a great deal of drift algae, The nearfield station is also located off the mouth of Hampton inlet and is influenced by tidal flow from the estuary. Thus, operational comparisons will have to focus on relative changes at a-given station in species composition and'the absolute abundance of selected species. I l All of the selected demersal fish monitored have shown signifi-cantly different abundances (CPUE) among stations, and three of the five species have also differed significantly among years (Table 2.3-3), implying that determination of " control" conditions is difficult. For almost all of.' these tua, precision in impact assessment is only moderate because of among-year variability. Knowledge of the age-structure of the population and use of age and growth parameters (NAI 1985b) can improve the ability to-detect impacts. Age and growth parameters for two species, cunner (1983-1984) and winter flounder (1982-1984), abundant in the nearfield discharge aree were , measured to provide additional precision to the catch estimates and a view of potential sublethal effects. Results for the first three years of life, when impact effects would be most pronounced, can be summarized as follows: ) 3 l SPECIES 1 GROWTH CUNNER WINTER FLOUNDER Sexes different? yes no Year classes different? yes yes (age 1 & 2 only) Percent change detectable 2-5% 3 - 4% Thus, depending on the species, sex and year class differences will have to be considered if measuring age and growth during impact assessment. However,. , variability of age and growth statistics was low, giving better precision than abundance estimates. 65'
I 2.3.2.3 Ep1 benthic Crustacea Because of its commercial importance, the American lobster has been studied in all of its life stages for 10-14 years. Average annual catches of all lobsters was fairly stable, varying less than the average monthly catch (Figure 2.3-16). Catches did not differ significantly among years (Table 2.3-3). Variations in catches of legal-sized lobsters, a primary concern to i lobstermen, were a result of natural variation combined with the effects of f
\
the change in the legal size limit. Catches ranged from 7 to 10 per 15-trap effort during 1975-1986, then dropped to three/15 traps in 1987. Although the variability was lower than that for total catches (Figure 2.3-16), this repre-sented a substantial difference to commercial lobstermen. Catches in the i 67-79 mm size class (2-5/8 to 3-1/8 inches carapace length), lobsters which f are approximately two years old, have been steadily increasing through 1985 despite decreased catches in the smaller size classes (one-year old lobsters) i (Figure 2.3-17). In 1984, the legal size limit was increased by the State of New Hampshire from 3-1/8' (79.4 mm) to 3-3/16" (81.0 mm), and catches of g i legal-sized lobsters decreased to their lowest point in 1984 and 1985. A number of adults which would have been of legal size under the old law were not harvested, causing increased catches through 1985 in the 79-92 mm size class (3-5/8 to 4-1/8 inches), which now contained both legal and sublegal sizes. A decrease in catches in 1986 in the 79-92 mm size class may have f been linked to lower catches in the 54-67 mm size class in 1985. Iobsters have shown consistent seasonal patterns, with catches highest from August through October. Catches to the north (L7) have been consistently (and significantly) higher than at the discharge (L1). Annual catches of other epibenthic crustaceans, Jonah crab and rock crab, were more variable (Figure 2.3-16). Both species had increasing catches from 1982 through 1985, then slight decreases in 1986 and in 1987 (nearfield station only). Catches of Jonah crab were generally highest in August (Figure 2.3-16), with no differences detected between nearfield and farfield stations. Rock crab catches, much lower than those of its sibling species, usually peaked in July or August, and were ::ignific:ntly greater at . I the nearfield station than at the farfield station. 66
l i l PEAK SEASON l 12 - l 8-z e - i 5 PEAK MONTHS
$ 6-2 i f 4-2-
o . . . .
- ~ a n 1 2 2 * :u 1
2 1 ! \ 2= 2 5 % l c& c 8 8 1 55 5 1
- E ;E l
< < j TEMPORAL VARIABILITY !
20 - i g AMONG MONTHS (n = 6 An - Nov) O AMONG YEARS (n .13 for lobsters, n . 6 for crabs) 15 - .. Lu o z 5 < o 10 - no z , D ll m a H
<c .
5- , 3 f S 0 8 3 3 . 2= 2* 2 5 c& c" " 5 E i 55 $5 l 3 3 ~2 E E
< < l I
i l Figure 2.3-16. Seasonal vs. annual variability (standard deviation) and j months of peak abundance (catch per 15-trap effort) for g adult lobsters and crabs. Seabrook Baseline Report, - 1987. (For CPUE of total lobsters, multiply by 10.) 67 '! 4 l
1 1 6 1: l
. , .5 l Y, 4 i- e t . 3 e ik a
. 1 gl E .g ; '
= (
I
,g l- !
E m! in Ei li M: li ;
, . [ E M -! I! ,
i : s a a a a a LM l' g il E"
! -S "4 Es i ,
8
~
8 8 ? FS . Z A W dl81 dVul SL U3d H01Y3 8 fo C 68
3.0 RESULTS i: 3.1 PLANKTON AND WATER QUALITY PARAMETERS Plankton and water quality programs of the Seabrook baseline period ) 'have included' water' quality sampling, phytoplankton, microzooplankton; and macrozooplankton. -During 1987 there was no additional sampling for phyto-l l plankton or microzooplankton. Results of those two programs were updated and: presented in dota11'in last' year's baseline report (NAI 1987b)-and are not- ] repeated here. The' plankton'and water quality programs presented in'this U 1987 baseline. report are those for which sampling was conducted during 1987: water quality (Section 3.1.1), bivalve larvae (3.1.2), and'macrozooplankton I (3.1.3). The.cummulative results-for all plankton programs', including phyto-
. plankton and microzooplankton, are discussed in Section 2.0.
3.1.1 Water Quality Parameters-Seasonal Cycles and Trends Three physical (temperature, salinity and dissolved. oxygen) and . five chemical (orthophosphate, total-phosphorus, nitrite, nitrate and ammonia) parameters were examined our a 10-year period to assess their temporal variability. Generally, parameters exhibited annual. cycles with one or two peaks; ammonia showed no distinct pattern (Figures 3.1.1-1 through 3.1.1-7). Water temperature was monitored in the nearfield both continuously (Station ID, 1978-1986, NAI 1987B) and periodically during the semimonthly. plankton cruises (Station P2, 1978-1987). Monthly.mean values derived from both sampling methods were similar (NAI 1980c, 1980d, 1981f, 1982s, 1984a, 1985a). Continuous temperature data were not available for January 1985~ through July 1986. Irradiance values, collected 1979-1984, and surface temperatures followed the same general annual cycle, with temperature peaks lagging irradiance peaks by one month (NAI 1985b). Bottom temperatures-(depth 16 meters at.MLW) showed truncated peaks which lagged one to three 69
t Surface - 20 -
-(
j ['. ,
/ . . . .]
15 - < '( o ? j.. W /.. D" . h 10 - oc . m O. 3 w 5-e ,, OVERALL MEAN {
.. ... .. 1967 j 0 , , , , , , , , , , , ,
JAN MB MAR APR MAY JUN JUL AUG SEP CLT NOV CED MONTH i 15 BOMom O -- L 10 - "/ . W sc . "3 **.*. g .. a: / w . .'
- n. 5- .,.* -
g ,
=
w OVERALL MEAN
... .. 1987 0 , , , , , , , , , , , ,
JAN RB MAR APR MAY JUN JUL AUG SEP CCT NCN MC MONTH
~
Figure 3.1.1-1. Monthly mean temperature at station P.2, all years' mean and 95% confidence interval for 1978-1987 and monthly mean for 1987 for surface and bottom. Seabrook Baseline Report, 1987. 70
I 8-
~ 6 o
4-4
$ 2-
_E E-
~
h o'." _ _ m. _ E _ __ AP SF / 8~ 1979 g 6-4- ' H I I IJ_
~
! l
!"O c2 m-
$ e JAN FEB MAR APR MAY JUN JLA. AUG SEP OCT NOV DEC 8- j 1980 G 6-L -
4-
$ 0 --
l; ; l;l;;;: : ; ; ; ; ; ; ; ; ;l; JAN FEB MAR APR MAY JW JLA. AUG SEP OCT NOV DEC 8-1981 G 6-4- , H N 2-0- - -
- JAN: FEB
- : MAR
- : :APR: :MAY: :JUN
- :JUL: AUG : : :SEP: :OCT: :NOV Frr DEC 8-
- 1982 o 6-L 4-
$ 2-0 g-g _
"" " " " - Eu, lIlllll!lll!l!;;;;;;;;ll JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Figure 3.1.1-2. Differences between surface and bottom temperatures taken semi-monthly at station P2, 1978-1987. Seabrook Baseline Report, 1987.
71
8-1983 g 6-L ' 4-
.a 2-
$ 0- -""- " " " " "
m
- : : ;;: l : ; ; ; : l: : ;; ;l : :
,JAN FYB MAR APR MAY JW .UL AUG SEP OCT NOV OEC g_ 1984 f., 6-y 4-2 o ,, .. g
_muBm E L___ _
-2 g ,, JAN FEB MAR APR MAY JUN JLA. AUG SEP OCT NOV DEC 5- 1985 G 4-g 3-ei: 2-b 3
$ 0 -- .
E - lA!!IAl!l !l 1l1l!lAl} l llI g, JAN FEB MAR ARP MAY JUN JLA. AUG SEP OCT NOV DEC _ 1986 o 6-
~
_..slI 4-
; . L. -
2-lAIAlIlll5l!!!!!!!l1l5ll 12 - JAN FEB MAR APR MAY JUN JLA. ALG SEP OCT NOV DEC to - 1987 o
- 8-h 6-4-
3
*~
0 --
--mmEE ER_ __
t lI I $ $!5l !$I Il $ IiI $ JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Figure 3.1.1-2, (Continued) i 4 72 ,
t (. (; 34 - Surface Salinity O T
---[,N .,, _.
.:g. 32 -
, y ...,,,4,,,,,;;
p......... ...s...... p . p g ,_ g
~
n : ;. i-: / m Y- w
- a. 28 - .
i / AU. YEAR 8' MEAN
/
tes7
$ .g E 26 -
t < a,
\ :l
- 1 24 , , , , , , , , , , , ,
JAN FEB MAR APR MAY JUN JUL AUG " SEP OCT to/ TC MONTH 34 , Bottom Salinity c . " " z 33 -
< N m -
o .L.....N . o 32 - V x '.*. e ;
-. A.....'l.**..**'.
.y x
31 -
\.
\,
j'...,...***<*...,. m '
. l H i / 1.LL YEARS' MEAN o.
30 -
'./
s. v
~ . . . 1987 29 , , , , , , , , , , , ,
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT PC/ DEC MONTH Figure 3.1.1-3, Surface salinity and bottom salinity at'neerfield station P2, monthly means and'95% confidence intervals over all years,'1978-1987, and monthly means for 1987. Seabrook Baseline Report, 1987. 73 l_________________________________________ _ _ _ _ _ _ _ _ _ _ ____._ __ _]
l ,
- Surface Dissolved Oxygen I
E y 11 - ,
?...% -
- Au. YEARS MEAN 1987 x -
w - 3o. h. . s
.N. :,....
g .'s,^ .*.... -
*~
$ ......"/.....,.M./
9-y x - 8 . , , ,,,,,,,,i JAN FEB MAR APR MAY JUN JUL AUG SEP OCT to/ DEC MONTH Bottom Dissolved Oxygen tt ....*% 5 11 -
/- . g., .,,,
Au. YEARS' MEAN ise7 w to - -
- o. .*. . ..
N, . m m
< o. -
. . .-s,. . /......
m ., . (3 * .. .... 3 y x 8-
--.- .k 7 , , ,,,,,,,,,,
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT POV OED MONTH Figure 3.1.1-4 Dissolved oxygen at nearfield station P2, inonthly means and 95% confidence intervals over all years, 1978-1987, and monthly means for 1987 for surface and bottom. Seabrook Baseline Report, 1987. j l j 74 4 l
i i l l Orthophosphate-30 -
.... *\
- a w . .\. ,,
n . g . 20 - \ / '.
! /
I
$ \ i. ' ./ \ /
% / \. '. .. ..
10 - ,
- , / '.
O ' L $ -
.. AU. YMRS MEAN 1987 g ,
q 0 . . . . . . JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NW DEC MONTH j i l a l Total Phosphorus 60 - , g . w So - l\ .- b '
,/ **.,
- x 40 - : \ ,-
$ l .
/
m 3E 30 - t '. s / 7 20 - ' g N.d../ Au. YEARS
- MEAN so.7 l
O 10 - - 5 0 . . . . . . . . . . . . JAN FEB MAR APR MAY JUN JUL AUG SEP OCT N'V . EC MONTH l Figure 3.1.1-5. Orthophosphate and total phosphorus at nearfield station P2, monthly means and 95% confidence intervals over all years from 1978-1984 and 1986-1987, and monthly means for 1987. Seabrook Baseline Report.1987. No data were collected for August in 1987. 75 l L_________.z__ . _ _ _ _ . . _ _ _ _ _ _ _ _ _ . _
Nitrate-Nitrogen 160 - . g 140 - ; w .
$ 120 - i
. : Au. YEAAS MEAN g ... .. 1987 w 100 - I. .
a ; m 80 - ! l . ,, 1 3 %
$ 60 - . ,
e . . I # 40 - m o
- ' N' ,
l
,f '
5 20 - 1/.* :
.. r O , , ,
W r
.....t...'...
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT to/ CEC MONTH 7, Nitrite-Nitrogen K 6-w /. b 5- CEARS MEAN , w
... .. 1987
/
- a. 4- ; e, m .~. ..- .
l ',- 2 3~ ' ' y \ . [' f 0 2 Y. .. 4 j s?%..
..l. -
0 i , , , , , , , , , , JAN FEB MAR APR MAY JUN JUL AUG SEP OCT to/ EEC MotRH Figure 3.1.1-6. Nitrite-nitrogen and nitrate-nitrogen concentrations at nearfield station P2, monthly means and 95% confi-dence intervals over all years from 1978-1984 and 1986-1987, and monthly means for 1987. Seabrook Baseline Report, 1987. 76
C
,E
'.' '.'... ~
N ,O I F
#' ,C T
=
. O ,r 2 e
- P v
. o
. n d
- . P osn
.E i l a
'.'.' S t a av ,
.'.*. t r7 s e8
,1'*. G t 9 r' .U d n1 l i -
- !l *. A e 6 i e8
- . .:llY .!:=
f c9 r n1 L a e a , U edd nin in J H f a o , .'.~ T t n N a 7 m .'.' O o4 c8 8
. 9 m '.
.N M s 9 7 1 A .' U n % 1 8 o
J i t 5 - 9 9 8 1 7 t o r a d9 r p
*.:: /. Y r n1 o t a f R e
- .A n m e
.'.. M e s os n c nrn i l
.'.'.' naf a oe e e s
- .i R cmsm r B a
N .P aya y A E A i l el k o M S R A E .
~;~. ~. .
,A R
nh yh o ot mnl nb mol o A ma mS t r a e Y. 7 '. t L 9 0 M A 1 . Y'.'.i., 7 1
; ,B 1
- : F .
3 _ '.'.l .N e r u A _ 0 0 0 0 0 0 0
- ~ ~
0 0 J i F g
% "4 0 0 0 3 2 1 0 9 8 7 3 2 1 1 1 1 1 mtF u- u.
mtamE4$E92
~M lIlltIll
/
. /: 1 ( months behind surface peaks. From 1978 through 1987, the temperature peak 4 occurred in July and August at the surface and from August to October at the bottom at Station p2 (Figure 3.1.1-1). Bottom temperatures were similar to surface temperatures October through April (Figures 3.1.1-1, 3.1.1-2). Hinor d temperature inversions occurred each year during winter months (Figure 3.1.1-2). Annual mean temperature at Station P2 in 1987 was similar to previous years at the surface (Table 3.1.1-1), though lower than 1985 and 1986, bottom temperatures were the second lowest observed in the past ten i years. The thermocline, typically est.ablished from May through September, was strongest in August six of the ten years, and in late June and early July the other four years (Figure 3.1.1-2). In 1979, 1980 and 1983, a substantial but temporary breakdown of the thermocline occurred in mid-summer, Other water quality parameters were monitored at Station P2 and Station P7 during fortnightly plankton cruises. Sal.inity concentrations were highest in December and January, reaching levels of >33 ppt, though in 1987 peak salinities occurred in March at the bottom (32.4 ppt; Figure 3.1.1-3). Salinities remained fairly uniform throughout the year, dropping only in spring between March and June, depending on the amount of spring runoff and rain. Significant rainfall in April of 198/ resulted in the lowest observed surface salinity for a single date (21.2 ppt). Spring salinity concentra-tions typically reached lows of 28-31 ppt. Bottom salinity exhibited the same seasonal pattern as the surface, but showed less variation within and among years (Figure 3.1.1-3). Annual mean salinities in 1987 for both surface and bottom were the lowest recorded in this study, reflecting below average salinities throughout the year, especially in April, June (bottom only), November and December (Table 3.1.1-1, Figure 3.1.1-3). Dissolved oxygen peaks occurred February through April in both surface and bottom waters. Dissolved oxygen nadirs varied from August to November near the surface and the bottom (Figure 3.1.1-4). Surface and bottom dissolved oxygen values in 1987 were similar to previous years (Table 3.1.1-1) though November values were somewhat elevated (Figure 3.1.1-4). Maximum orthophosphate and nitrate concentrations occurred in winter (Figures 3.1.1-5 and 3.1.1-6); nittate was consistently lowest in midsummer. Total phosphorous and nitrite showed fall, winter and occasional spring peaks (Figures 3.1.1-5 and 78
S 1 7 82 84 07 83 62 _ I U R C 6 9 1 6 35 99 4 E 54 70 4 t 64 1 2 3i 27 21 38 80 91 1 1 95 831 i N
)
t - I K ) N ) I I ) ) b _ A L 5 35 75 31 08 56 1 2 04 55 72 64 76 1 5 -- -- - - P 8 9 94 87 22 21 90 95 G 1 5 4 3t 31 1 1 N t t 1 t I R U D ) ) ) ) )
) 1 1 1 ) )
D ) 42 34 83 73 1 6 26 96 7 3 28 5 7 7 2 E 7. N 97 90 69 78 00 35 20 1 4 00 74 58 O a98 4 t t I 8 85 65 04 11 02 93 4 56 4 0 1 98 6 7 6 70 S1 T 9 5 4 31 31 1 1 1 1 24 3 1 1 1 A A 1 t 1 ( I t t t I E E , I MT R R A SO V ) ) ) ) ) RP ) 1 ) ) ) ) EE F 84 23 49 22 83 89 3 7 15 54 3 2 2 6 TR O 57 34 03 91 47 99 24 80 03 86 39 E 3 ME T 8 93 74 1 4 1 2 97 81 94 5 5 245 1 6 75 AI N 9 5 4 3t 31 ( 1 1 4 2 3 5 10 21 RD E 1 E ( I t t t 1 AL I 1 t PE C S I YA F .) ) ) ) TB F 1 1 ) ) 1 ) I E 82 63 47 1 1 05 57 24 1 6 04 7 9 0 LK O 80 30 84 05 66 33 1 8 A0 C 2 40 61 21 0-U0 8 83 76 1 3 22 91 96 75 4 8 286 7 7 0 - QR O 9 5 4 3( 3E 1 1 1 5 2 2 3 13 3 8 D 1 E t 1 I 1 t 1 RA A ( EE t TS A N N A ) ) ) 1 ) ) ) 1
. E I ) )
F7 H 24 71 96 21 00 30 2 3 0 3 2 3 21 5 3 O8 9 L 1 8 73 31 81 34 97 49 88 59 91 44 27 N1 A 9 83 79 1 2 21 92 97 1 0 3 2 3 2 3 54 64 O - U 1 6 5 3t 31 1 1 1 2 t3 5 4 9 36 I6 N t t 1 i i ( 4 E T8 N A9 A I1 R . AO VD 1 ) ) ) 1 ) ) ) I ) 1 2 8 A 66 56 74 22 77 58 20 68 7 9 38 7 3 9 F 0 78 07 1 6 45 21 82 1 1 96 1 5 38 17 1 O4 8 8 9 87 72 22 21 01 94 0 76 1 7 3 9 81 4 8 n S9 1 5 5 3i 31 1 1 1 1 ( 3 7 t 5 I 411 04 i tT1- t t ( i 1 t i d D8 I7 e s C9 u I1 F ) ) ) 3 ) ) I ) ) I I s F , 9 65 66 24 77 29 97 5 9 2 9 1 8 34 2 3 d E2 7 78 39 88 47 03 66 75 1 0 75 32 49, o DP 9 h C 1 87 67 1 3 22 03 94 92 5 3 1 6 81 72 t 4 f 5 4 3t 31 1 1 1 5 1 6 6 3 10 44 e Ot t i ( I t t ( i m
) I t AT f A o ST NS ) ) )
1 A ) I ) ) ) ) I I 1 E 8 73 1 2 83 45 80 76 8 9 0 9 21 81 66 / H1D. 7 39 66 63 76 28 08 59 50 1 1 06 49 g E 9 p LI 1 86 65 1 3 21 00 08 9 9 20 26 26 1 0 AF 6 5 3t 31 1 1 1 I 2 34 4 511 521 0 UR 1 I 1 E t t 3 NA I i ( NE AN 1 s
- 1 t
/ i
. g m 1 a i
- t l 1
l n s n 1 C e u o i
) g e r i 3 R t t y t o t E e pe c e a h) c e E. T ec ra n
o pc a m hc t a n h) pl p ) 1
)
1 I e I E o o s1 l t B M uf t iyrf t df t s/ og o/ / g
/ / e A A t r t t er t h g pp ep ep ap g d g d T R au o t u o vu o hp A rs b i s b l s b p( t( tI ii w m P ep n o o l i i a n o i s h a r r o l m l s t t t t m e e a i r o i i m B T S D O T N N A a b l
3.1.1-6). Ammonia maxima usually occurred in fall or spring. In 1980, when ammonia concentrations were exceptionally high throughout the year, the peak occurred in July (Figure 3.1.1-7). Orthophosphate and total phosphorus concentrations in 1987 varied somewhat from baseline conditions. Orthophosphate concentrations in 1987 were bimodal with higher than normal values in February, June and July (Figure 3.1.1-5). Total phosphorus concentrations in 1987 were highly variable with higher than normal concentration in February, May, September, October and December. Nitrite concentrations in 1987 were well below normal March through June when no nitrite was detectable (<1.0 pg/l at Station P2; November nitrite levels were above normal (Figure 3.1.1-6). Nitrate levels were typical of past years with somewhat higher than normal concentrations in February (Figure 3.1.1-6). Ammonia concentrations in 1987 were consistent with previous years, with s]Ightly elevated levels in August and October through December (Figure 3.1.1-7). 3.1.2 Bivalvia Veliger Larvae 3.1.2.1 Community Bivnive veliger larvae were identified and enumerated from oblique tows of 76-pm mesh nets from April through October 1976-1987 at one or more of the Stations P1, P2, and P7 (see Section 3.3.7.1 for Nya arenarla results and Figure 4.1-1 for station locations). Nytllus edulls was clearly the dominant species, while Noteranonia squacula, #1 ate 11a sp., Solenidae and Nodlolus modlolus were secondary dominants (Table 3.1.2-1). l Flate11a sp. was present April through October, with highest abundances usually occurring in June (Figure 3.1.2-1). Nytllus edulls, Solonidae and Nya truncata were usually present by mid- to late May- Nytllus edu11s and Nya truncata peaked primarily in June or July. Solenidae peaks were noted in June, late August, September, and October, possibly due to 80
- 7 82 9P 1 2 6 8 3 1 3 1 0 1 1 4 1 0 1 1 m p 6 - 7 1 4 8 0 2 1 4 1 2 1 0 1 1 H P 7 1 < < < < NG I U O ER AH7 VT8 7 4 5 9 8 1 2 1 2 1 0 1 1 R 9 P 5 1 1 < < < < AL1 6 LI 8 R , 9 _ RPT 1 - EAR 1 1 1 1 1 0 1 1 G - O 2 1 2 0 3 I DP P 6 1 1 1 < < < < < LI E EMR V ME EON 1 1 1 VRI 7 3 3 6 3 1 2 1 1 1 LFL P 8 < < < < < < A E V7 S 4 I PA 8 B _ B 9 D 1 FNK 2 7 4 8 7 1 2 1 1 1 1 1 0 OAO P 7 < < < < O - N2R OPB I A T ,E I 1 S 7 7 7 3 8 1 2 1 1 1 1 1 0 SP P 4 1 1 1 < < < < O PS . 3 M N8 8 - OO7 9 CI 8 1 T9 2 9 4 7 4 1 3 1 1 1 1 1 0 TA1 P 5 1 1 < < < NT - ES2 C 8 _ RT9 EA1 P 7 4 4 8 3 8 4 5 2 1 1 1 0 S , P 5 1 < < LWR LOE 2 ATB 8 - R O 9 ETT 1 VEC 2 4 1 9 9 6 3 4 2 1 1 1 0 ONO P 4 2 < < 1 s
- u 2 c
. i 1 a n l a a 3 u m l c s i l E a u s e L u l s a g B s q o i a c a s A i s i d i i m i T l .
d i a v a h l S u a p o l i l t t n a E d i s m o r a a l e v I e m s e a v c a t a C o a s a n i n b c n E s n l u a d e B u e P u a l l l i r r a p o S l r e o u n a r t m o d i e t i s e e o c e t y t s d i p l a y h a y c a r e i o o t a l e
# R H H S S N O N # P T
a wasPREsen 10 - Hlatells a meAamca f 8A
$ 6- '
4-2- f 0-- ( 34 1 234 1 23 4 1 234 1 23 4 1 234 1 234 APR MAY JUN JUL AUG SEP OCT 12 - Mytilus edulis (a) l *^"8 P '88"1-, 34 1 234 1 234 1 23 4 1 23 4 1 234 1 234 APR MAY JUN JUL AUG SEP OCT 12 - Modlotus modiolus (b) 3 WARSPREEGM 10 - E YEARSHGHABUNDANCE' 34 1 23 4 1 234 1 234 1 23 4 1 234 1 234 APR MAY JUN JUL AUG SEP OCT I Heteranomia squamula (b) j g 7 ABUNDANCE 12 ] 3 4 1 23 4 1 234 1 234 1 23 4 1 23 4 1 2 3 4 APR MAY JUN JUL AUG SEP OCT 12 - Solenidae (b) 3 WARS PRT.SDR 10 3 mM ABUNDANCE O 34 1 23 4 1 234 1 234 1 234 1 234 1 234 APR MAY JUN JUL AUG' SEP OCT Figure 3.1.2-1. Number of years present and number of years in high abundance (2 50% of seasonal peak abundance) of bivalve veliger larvae by week at station P2, 1978-1987. Years enumerated: a. 1976-1987; b. 1978-1984, 1986-1987;
- c. 1979-1984, 1986-1987. Seabrook Baseline Report, 1987.
82
10 - Mya truncata (b) , op. 8- B YEARSHWABUNWCE l 34 1 234 1 23 4 1 23 4 1 2 3 4 1 23 4 1 234 APR MAY JUN JUL AUG SEP OCT 10 - Placopecten magellanicus (b) l E YEWFRESe# 8- g YEARSHOHABUNCMNCE 3 4 1 234 1 234 1 23 4 1 2 3'4 1 234 1 23 4 l APR MAY JUN JUL AUG SEP OCT 10 - Spisula solidissima (c) 3 4 1 234 1 234 1 234 1 23 4 1 23 4 1 23 4 APR MAY JUN JUL AUG SEP OCT 8~ Macoma balthica (c) 1 3 4 1 234 1 23 4 1 234 1 234 1 234 1 234 APR MAY JUN JUL AUG SEP OCT Figure 3.1.2-1. (Continued) 83
i differential spawning of the three component species (Ensis directus, S111gua costata, S111gua squama). Heteranomia squamula was usually present by early ] June, with highest abundances July through September. Nodlolus modfo1us was usually present by mid-June and has been highly variable in terms of peak abundance, with peaks in early June (1978) and in early October (1986). Spisula solidissima and #acoma balthica usually were not observed'until July ; I and August, respectively; these taxa peaked in late summer or fall. Placopecten magellanicus was present sporadically throughout the sampling period, with no clear seasonal peak. In general, larval peak abundances and periods of occurrence in 1987 were comparabic to previous years with some exceptions. In 1987, Sp/sula solidissima peaked in early June, slightly earlier than usual and, as in 1986, Nacoma balthica larvae were not observed (NAI 1987b). Station P1 (llampton Harbor), added to the sampling program in 1986, and offshore Stations P2 (nearfield, intake) and P7 (farfield) all displayed similar patterns of species composition and abundance. Entrainment samples were collected within Seabrook Station (E1) July through December 1986 and April through June 1987. In both years, comparison with intake Station P2 demonstrated similar species composition at Station El but substantially lower larval densities. In 1987, Station El densit.ies for Hlatella sp., Solenidae and Nya arenaria were substantially lower than densities observed at Station P2 (Table 3.1.2-2). Differences between Stations El and P2 may be attributed to dif-ferences in sampling. Station El sampled water from the cooling water intake, at a depth of about ten meters, while Station P2 was sampled via oblique net tows which integrated the entire water column. In general, bivalve larvae are found in near-surface waters for the majority of their planktonic existence, thus fewer larvae would be expected at a depth of ten meters, and consequently lower abundances would be expected at Station E1. Additional variation between stations may have been introduced by sampling at different times or different days, allowing small and large scale patchiness to affect the larval densities. 84
) l TABLE 3.1.2-2. DENSITIES OF DOMINANT BIVALVE VELIGER LARVAE IN 76-pm MESH l NET COLLECTIONS ON OR NEAR THE SAME DATE AT NEARFIELD STATION, P2, AND ENTRAINMENT STATION, El, APRIL THROUGH JUNE 1987. SEABROOK BASELINE REPORT, 1987, i l I APR APR APR MAY MAY JUN JUN JUN 21 22 30 07 26 01 03 08 ALL ! 1 l l 4 i Hytilus edulis P2 <1 - 0 0 0 4 - 79 14 ! E1 -
<1 0 0 0 - 2 61 -- 11 l
#fatella Sp. P2 23 -
1084 1699 866 6433 - 7320 2904 E1 - 4 <1 363 256 - 856 1237 453 q Solonidae P2 <1 - 0 1 33 328 0 26403 4461 E1 - 0 0 0 21 0 32 725 130 hya arenarla P2 0 - 0 0 0 0 - 82 14 . 1 E1 - 0 0 0 0 - 0 6 <1 l l
- Sample not collected i
1 I l 85
3.1.2.2 Selected Species Nya arenarla l l This species is discussed in Section 3.3.7. Nytilus edulis Umboned veligers of Nytilus edulis were usually present by mid- to late May (Figure 3.1.2-1). Once present, they occurred consistently through-out the sampling program. The protracted presence of larvae was due to recruitment patterns and duration of larval lifestages. Major spawning events in Gulf of Maine mussel populations may be limited to temperatures above 10-12*C (Podniesinski and McAlice 1986). Spawning of N. edu11s in Long Island Sound was found to be asynchronous both within and among local popula-tions and to occur over a two to three month period (Fell and Balsamo 1985). Spawning of some Long Island Sound mussel populations was also restricted by limited food availability for most of the year, resulting in sporadic spawning events (Newell et al. 1982). Therefore it is probable, based on the reproductive behavior of #. edu11s, that recruitment of larvae to the plank-ton of New llampshire coastal waters occurred throughout much of the sampling program. Recruitment from non-local sources was probable, as water masses may move large distances over the three to five weeks required for larval development at ambient temperatures (Bayne 1976). Delay of metamorphosis until suitable settlement conditions are encountered can prolong planktonic existence for up to 40 days, depending on temperature (Bayne 1976). These factors suggest that planktonic recruitment to the study area was intermit-tent and prolonged, and that duration of planktonic life varied over the sampling program as temperature conditions changed, liighest abundances of Nytilus edu11s larvae ucually occurred between early June and early July (Figure 3.1.2-2), although in 1980-1982 abundances in late August, September or October were as high as in early 3 summer. Peak abundances ranged from 6 x 10 /m in 1982 to 3.3 x 10 /m in 1979 (NAI 1987b). The difficulty in assessing the variability in this 86 l
) :/.;N'*.y . tc 2-O
- 1
. t c
O
..*.l-4
. p e
S 3
. p N e A : S E !. 2
- M ' l*g . p s N
's' e l 2 o Y. S aP p Q A t ' ,1
- v DE E M '
. p 1
rnR WYL S e eo t i e S M 4 nt n R E '
. g i ai A E '
u E tl Y W A ese L 8 L 9 7 j*.'.* . g 3 c nd a A 1
- A 2
u el B d e iik
- . g
- i. u f f o A nro
% 1 oa
,1 .'e'
- . g ceb A
u K n
~ E %
4 - E 5 tS u . l J u W 9 a .
.. D d e
~
=~N. - .
. l 3
u N A na7 av
. l J
2 J u H T N ea cl n r
.. 1 O a s
.. .l M di u nl
. J uu
.. m
.n 4 -
bd s a e J 3
'n a uy s
. n el u
J mil
~' .*.' .../ 2 - yya t
, ': : . l : I : . . . n J
a l M k
- .*I 1 ere8
*:::.I ! . n eov9
/l J u Wf o 4-
. ~
- .l , y a
M 2 3 - 2
.a y
./ M 2
y a 3 1
./ -
M 1 M y a e r u g i
-/.p 4 r
r A 3
- . rp A
2 -
.r p A - - ~ - * .
6 5 4 3 2 1 0 t ul:csGs O_myO Cu Csa i O23mA eo' mM
l population is probably compounded by patchiness caused by discontinuous recruitment both spatially and temporally (Bayne 1976; Podniesinski 1986). Collections taken within several days of one another, even during peak months, varied by zero to three orders of magnitude (NAI 1981c, 1984a). f a t In 1986 and 1987, bivalve larvae were collected within Seabrook Station in order to estimate larval entrainment. In 1987, offshore and entrained N. odu11s densities over all dates were similar (Table 3.1.2-2). f Ilowever, in 1986, some weekly densities differed substantially between the two stations, probably a result of small-scale spatial and temporal varia-tions. Although variability was high among years, overall spatial vari-ability was low. Ilistorically (1982-1984), no significant differences had been found between Stations P2 and P7 when weekly abundances were ranked (NAI 1985b). 3.1.3 Macrozooplankton 3.1.3.1 Community Structure Temporal Patterns Historical analysis (1978-1984) of the macrozooplankton assemblage at the nearfield Station P2 showed seasonal changes that were heavily influ-enced by the population dynamics of dominant copepods Centropages typicus and Calanus finmarchicus, with other taxa, particularly meroplankton, exerting short-term influences, especially during the spring and summer (NAI 1985b). llistorical seasonal assemblages (1978-1984) established by numerical classi-fication on the basis of similarities in species composition were verified by discriminant analysis, and in turn used to evaluate 1986 and 1987 collections. In all cases, new collections were placed in the group with the majority of historical collections from the same time period. This is an indication of the similarity of 1986 end 1987 assemblages with previous years. 88
)
~ ~
Winter abundances have been. typically' low, with the population composed mainly of copepods Centropages typicus (groups 1 and'2) and #etridia sp. (group 2 only)(Tables 3.1,3-1, 2). Winter abundances of C. typicus in [ 1987 were an order of magnitude lower than previous years, and 1986 and 1987 winter abundances of copepods Tortanus discaudatus and Tomora longicornis were higher than previous years (Table 3.1.3-2). ) The months of March and' April were characterized by the beginning l' of the spring warming trend and initiation of thermocline formation (Section i 3.1, Figure 3.1.1-2). Reproductive activities of barnacles at.this time result in a tremendous influx of Cirripedia nauplii and cyprids, which distinguish this assemblage (group 3). Copepods Centropages typicus and Calanus finmarchicus are also dominant components of this assemblage (Tables 3.1.3-1,2). The late winter-early spring assemblage in 1987 was similar to previous years with the exception of C. typicus abundance levels, which were two orders of magnitude lower than the 1978-84 average (Table 3.1.3-2). Heavy rainfall in April, 1987 caused salinity to drop to the lowest value observed since the study began in 1978 (21.2 ppt at P2, NAI 1988). This may ] have affected C. typicus densities,.as its reported salinity preference is 1 above 30 ppt (Gosner 1971). i i In most years, spri..g collections were marked by.a transitional assemblage (group 4), composed mainly of Calanus finmarchicus along with , other microcrustaceans (C. typicus, Netridia sp., Evadne sp. and Temora long/cornis), the holoplanktonic mollusc Limacina retroversa, and larvaccan Olkopleura sp. (Table 3.1.3-2). The transitional period in 1987 consisted l only of early May_ collections, coinciding with continued low surface salinity. F (Figure 3.1.1-3). Mean group densities of dominant taxa in 1987 were all an l order of' magnitude lower than those historically (1978-1984)(Tetble 3,3.1-2). ! i i Late spring-early summer (late May-July) conditions showed rapidly increasing surface temperatures.along with stabilization of the thermocline (Figures 3.1.1-1, 3.1.1-2). Calanus finmarchlcus was typically the dominant organism during this time period, which along with the larval decapods, 83 - _ _ _ _ - - - _ _ _ _ = _
I e @N _M44 M4 .. . eJ - m o a . M M4 #MtG
. . OM N M & #Med h
N ON m WmMt42 N k 4 NMS hd M 4 DOMNd h N Me C - g 44 ..- b d MM N . M SNt42 N *MM N m GON446 4 OMNM w M 80944n gN N WmN D h. - em OMt4 i t WMM q M t DON 4C N N eOMM C k w N44e 1 I t OM M Wees N OmWM m G&nN4& g & C 00 M end NMm ' b N WM So gM M 4 OMNm M b . f< W @M
.M M OONtn n N WM 8 - eC-Nem , ;
D$ f W M f g M DOMNfC g N MNM ,
- e em ;
e e N' O Nt ag M M a N WMt C W M NC M A $ l g 4 Mt O g e M Wem OMN N N @ 04 4
- a 0-N k i
}. <
k' S
- l I E 0
$ N A
( M
? j g ? ! I-
- up - 3
; a g ,
g L - e y*e 9 - te : i
=
r i
* ~
H TTE i 3 t
- l 0 u l g E23 E 3 & 5 A e [. j
. - N M . M 4 ~ .
90
G9I 0 7 44307 09051 058 1M 0 1 31 1 56 5 41 1 2 L I 1 2 21 4 - A ,R N2C OPS
/
3 1
)
S I d AND e EO u SI Y n TB . i NA Q 0000000 t I TD E 0 00000 n SE R 1 1 1 1 1 1 o G I F c NDF 6 ( I LI 8 RES 9 RI S 1 UFA 3 0000000 CRL s 0 00006 CAC 0 9 7 7 09 9 - OE 0 0 1 7 03 NS 0 1 31 _ A A 1 XT / AA) # T R SE TNB NOM AI E NTC . I CE Q MED E 5300050 00333600000 03030 020 OL - 4 R 930009 9 009 9 9800000 09090 090 DLY 8 F 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 OR 9 FCA 1 O U - NN 8 EOA 7 3 CTJ 9 m 0000000 00000000000 00000 000 NK( 1 N0 0000002 00000000000 00000 000 EN A0 8742923 7 969 1 21 431 1 021 1 9 057 RA7 E0 03221 1 58374332222 2241 9 269 RL8 M1 2 31 1 97 52 1 32 UP9 / 2 2 C01 # C0 OZD . ON7 FRA8 OC 9 A) 1 YMR C ET e NFBR t EOMO i U EP d QNCE o EOER p RI D s e s s s s FT E s u sa p u u su ua AYN u at s us csca t uc cs TCLI c . nai cr .ciin a ci . i r NI UL iap pvs scur ad n p i ep nh a d aih h e EFJE pvs .rccsu vpc s cv CI ( S yr niao yo porina . ryr . ro . RS A t asarcc t rsscaracp at aps arp ES6B S l ugesi . t u imegss l nsu mt s PA8 E s nemig psensgnmei sn n ne L9K I eaal adn seraenialda aeisa i rs DC1 O C gil e o g l gof e r i gfrl f r N O E ad o s su epsec ua ssl aaaaal d a au ALOR P pecaiu i pncp siaue sne ATB S opot sna doiooaust nl poul o uil EM A ridt yar ircdrrnyt ap i r n pd ncp CRNE t ruimt o rt sut oamit o rt aou aao NOOS nregorm rneenml ogrk rnlk e l nk ANS eisaeoe eeiseeaeaoi ieais aii D NYR I CCPSNTT HCLPCTCNSTO CCCOP CLO UBAS B PI 7 ADMS , 8 EOY 3 9 NMCL 8 1 AR A 9 , _ EONN 1 3 MFI A 8 9 9 1
. 7 7 ,
2 982
- 1 98 3 - 1 9 - g 1
8 7 , 1 rn ei 96l 2 t r 3 P 1 8l 8 np U 9 a 9 iS E O r1 W g e ,F . r1 L R e- y n _ B G t4 e t0 el i . A n8 t n8 t r r T aa _ i 9 a i 9 p W1 L W1 LE S _ 1 2 3 4 _ e "- _ I
1 425 21 656465521 81 8 0 81 2 8 84631 1 1 1 3 1 1 _ 3
/
Q 000000000 000360006 000 E 00 00 0 0 000480008 000 R 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 F 6 8 9 1 3 m 000000000 0000000G0 000 0 00 00 0 0 000000000 000 0 00 20 3 8 0001 30006 07 9 0 69 06 3 828 57 67 2 7 2 1 88 66 4 608 1 32 4
/ 51 1 2 Q
E 2303 066806026 000750002 009 4 R 9808 09 980987 9 000980006 007 8 F 1 1 1 1 1 1 1 1 1 1 1 9 1 8 7 3 9 m 0000 000000000 000000000 1 N0 0000 000 000000000 000000000 000 A0 857 0 009 06 307 7 007 9 208 98 056 E0 31 95 1 7 09 65439 36847 31 92 535 M1 221 1 033221 1 1 60751 11 41
/ 1
# 22 1 a
p o l a a ap a e g p t e co o i m il l d ga a o & eg g p a s ves se e as s u rmus sum p eos s s u s c o t u uc o onu u u c i i n& ac ci& c zit c t i n h pa y p r cs saupdi s ih pca .sssm i p a m t o c ru al eeay noct pa n yre puama y a t ao sl neh S E sp i g mo . azsi s sg mz oet t h I es n n i ph e sn siaps s s C g po
. i ssp fu i p desl gre ei gf p .gu esmeesg e g . g e
E aasl pat s sau a spaps a apa P S pi s i c upea ps sp unp psp odea usdyrnol t our osnoo o o rinr nuinearpt rnenruigr rnr t rdo al ract t oi t acotl cnt t ot nt am l ot gnrnk g nl ndnaran nd n eeve aueeaoeia eaaoeuare eoe CMET CEMMCTCOS CCCPCECCC CPC
)
d e u n i t n o C (
)
t - r 2 n ge 3
- o c nm i m P ( ru 1 U pS O g S r 3 R n y e G i el m l E r t r L p m l B
aa u a S LE S F A T 4 5 6 7 u l l
[ euphausiids and small copepods formed the basis of group 5 (Table 3.1.3-2). 1937 collections in this group extended into August, without a definite l transition into the summer assemblage. Average group abundances of several species (Metridia sp., Meganyctlphanes norvegica, Tartanus discaudatus, and Olkopleura sp.) were an order of magnitude lower than 1978-1984 densities, coinciding with higher-than-average surface temperatures and continued lower-than-average salinity (Figures 3.1.1-1,3). The summer assemblage (mid-July - mid-October, group 6) occurred during the period of peak temperatures and maximum thermocline (Figures 3.1.1-1, 3.1.1-2; Table 3.1.3-1). Historically, populations of Calanus finmarchicus and Centropages typicus reached peak or near peak abundances at this time, while abundance levels of other copepods decreased. Meroplank-tonic larval stages of decapods Cancer sp., Carcinus maenas and Crangon septemspinosa, and cladoceran Podon sp. all reached peak abundance during this period. The summer assemblage in 1987 was similar to previous years, with two exceptions. Calanus Ilnmarchicus, an oceanic species (Gosner 1971), mean densities in group 6 were much lower than those observed historically (1978-1984). Estuarine species Centropages hematus, which has a salinity preference of 1-31 ppt (Gosner 1971), had abundance levels that were an order of magnitude higher than historical average (Table 3.1.3-2). Low salinity levels, beginning in spring and continuing throughout the year, may have affected 1987 abundance levels of these two species. The fall macrozooplankton assemblage (group 7) coincided with ! declininy. temperatures and degradation of the thermocline, characterized by l fewer species and lower abundance levels than previous assemblages. Histor-ically, copepod Centropages typicus has been the only taxon which occurred abundantly, with Podon sp. a secondary dominant in the group. 1987 collec-tions in group 7 had a similar species composition, with mean group abundance levels of these two species an order of magnitude lower than those observed historically (Table 3.1.3-2). The estuarine copepod Centropages hamatus, historically not an important component of this group, had fall densities in 1987 that were an order of magnitude higher than those observed historically (Table 3.1.3-2). 93
i Spatial Patterns The spatial distribution of most holo- and meroplanktonic species in the study area are governed primarily by local currents. Hydrographic j studies on temperature and salinity have shown that nearfield Station P2, and farfleid Station P7 are exposed to the same water mass (NAI 1985a). Further-more, bivalve larvae studies suggest that areas at similar depths and dis-tances from shore (such as P2 and PS) have similar species composition (NAI j 1977a). Thus no spatial differences in the mero- or holo-planktonic macro- 5 zooplankton abundances, percent composition, or rank would be expected among Stations P2, P5 or P7. This has been confirmed in examinations of the annual percent composition, percent frequency and rank dominance scores (RDS) of dominant species followed by nonparametric testing of apparent differences (NAI 1985b, 1987b). Species composition among holoplankton was similar among the three l stations in 1987 es well. Percent composition gives an idea of how total l annual abundance compares among the three stations. Copepod Centropages typicus had highest percent composition at P2 and P7, and Cirripedia had second-highest percentages. At Station P5, Cirripedia were highest in percent composition, followed by C. typicus (Table 3.1.3-3). The only other difference noted among stations was a higher percent composition of Tenora long/cornis at P7 in comparison to P2 and PS. These species did not show significant differences among stations in semi-monthly abundances (Table 3.1.3-4). Rank dominance and percent frequency of occurrence give an Indica-tion of hcu frequently a taxon has been a dominant. C. typicus and Calanus linmarchicus were the top two species in ranks at all three stations (Table 3.1.3-5). Stations were sinnilar in species ranks except for Pseudocalanus sp., which had a higher rank at Station PS (3) than at P2 and P7 (6 and 5, respectively)(Table 3.1.3-5). In addition, Tortanus discaudatus had a higher rank (7) at P7 in comparison to P2 (11) and P5 (14)(Tablo 3.1.3-5). These species did not show significant differences in abundances (Table 3.1.3-4). 94
TABLE 3.1.3-3. COMPARISON OF PERCENT COMPOSITION (AND PERCENT FREQUENCY OF OCCURRENCE) 0F SPECIES IN MACR 0 ZOOPLANKTON COLLECTIONS AMONG STATIONS P2, P5 AND P7, JANUARY-DECEMBER 1987. SEABROOK BASELINE REPORT, 1987. P2 P5 P7 l l Centropages typicus 33.0 (100) 22.5 (100) 24.3 (100) Cirripedia 19.6 (42) 34.6 (42) 10.8 (42) Calanus finmarchicus 16.1 (100) 17.1 (96) 14.3 (100) Tomora long/cornis 5.8 (96) 4.5 (96) 16.8 (96) Cancer sp. 5.7 (62) 4.2 (67) 6.5 (62) Podon sp. 2.7 (58) 1.2 (67) 1.4 (67) Pseudocolanus sp. 2.2 (92) 1.5 (100) 3.1 (96) Centropages hamatus 1.9 (75) 1.3 (50) 1.4 (71) Eualus puslolus 1.7 (100) 2.6 (100) 3.9 (100) Carcinus moenas 1.5 (54) 1.2 (58) 1.9 (54) Centropages sp. 1.5 (79) 1.5 (83) 1.8 (88) Tortonus discaudatus 1.1 (83) 0.5 (75) 1.0 (83) Olkopleura sp. 1.0 (92) 1.4 (83) 1.0 (88) Evadne sp. 1.0 (58) 1.3 (67) 0.8 (71) Limacina retroversa 0.3 (67) 0.1 (75) 2.9 (83) Sagitta elegans 0.6 (96) 0.2 (88) 2.2 (92) Obella sp. 0.5 (42) 0.5 (62) 1.9 (58) Nysis mixto 0.1 (29) <0.1 (29) 0.4 (25) Diastylls sp. <0.1 (92) <0.1 (79) <0.1 (62) l l 95
TABLE 3.1.3-4.
SUMMARY
OF 1987 BIWEEKLY ABUNDANCE COMPARISONS BETWEEN STATIONS MADE USING WILCOXON'S TWO SAMPLE TEST. SEABROOK BASELINE REPORT, 198/. TEST PARAMETER TESTED P2 v. P5 P2 v. P7 PS v. P7 Holoplankters Calanus finmarchicus NS NS NS Temora longicornis NS NS NS Centropages typicus NS NS NS Limacina retroversa NS NS NS Tortanus discaudatus NS NS NS Sagitta elegans NS NS NS Meroplankters Crangon septemspinosa NS NS NS Carcinus meenas NS NS NS Cirripedia NS NS NS Tychoplankters Neomysis americana NS NS NS Pontogenela inermis P2>PS* P2>P7** NS Dedicerotidae NS NS NS Blastylls sp. P2>P5** P2>P7*** P5>P7* Other Total Abundance NS NS NS
*significant at .01<p5 05
** highly significant at .001<p50.01
***very highly significant at p5 001 The probability of a type I error (falsely accepting a difference as significant) is 5% for any single test, but the probability of at least one type I error in this whole table (which contains 52 pairwise comparisons) is much greater than 5%. Therefore, only results that are very highly significant should be viewed as true differences.
96
. 1 TABLE 3.1.3-5. COMPARISON OF RANKa (AND PERCENT FREQUENCY OF OCCURRENCE) 1 0F DOMINANT SPECIES IN MACR 0 ZOOPLANKTON COLLECTIONS AMONG STATIONS P2, P5 AND P7, JANUARY-DECEMBER 1987. SEABROOK BASELINE REPORT, 1987, i l l ) l P2 P5 P7 i Centropages typicus 1/2 (100) 1 (96) 1 (100) Calanus finmarchicus 1/2 (100) 2 (96) 2 (100) Temora long/cornis 3 (96) 4 (96) 3 (96) i l Eualus puslolus 4 (100) 5 (100) 4 (100) j Crangon septomspinosa 5 (100) 6 (96) 6 (96) l Pseudocolanus sp. 6 (92) 3 (100) 5 (96) Neowysis americana 7 (100) 11 (92) 11 (92) Olkopleura sp. 8 (92) 7 (83) 10 (83) Pontogenela inermis 9 (100) 12 (96) 19 (79) Sagitta elegans 10 (96) 10 (88) 9 (92) Tortanus discaudatus 11 (83) 14 (75) 7 (88) Centropages sp. 13 (79) 8 (83) 8 (88) Oedicerotidae 14 (92) 9 (96) 13 (88) a based on Rank Dominance Score. 97 l
l l Tycho- and hypoplanktonic species, on the other hand, are often , strongly associated with particular substrate types. Substrate type and complexity, along with proximity.to Hampton-Seabrook estuary, may account for some of the differences observed among tychoplankters. Historically, Neo-mysis americana, Pontogenela inermis, and Diastylls sp. had higher abundances at P2 where substrate is sand and cobble than at P7, the station farthest to the north where the substrate is mainly sand (NAI 1985b). A similar trend was confirmed in 1987, although differences were very highly significant only for Blastylls sp. (the number of tests performed necessitates a more stringent significance level to avoid a type I error) (Table 3.3.1-4). At Station PS, where substrate is largely ledge outcrop and cobble, 1987 den-sities of P. Anermis and Dlastylls sp. were lower than at P2 but did not meet significance level criteria. Amphipods in the family Oedicerotidae showed no significant differences in 1987 abundances among the three stations. 3.1.3.2 Selected Species Calanus finestchicus Over the length of this study (1978-1984, 1987) Calanus finmarchicus has been a dominant species in the macrozooplankton assemblage (Table 3.1.3-2). Historically, copepodites exhibited greater abundances than adults, a trend which continued in 1987 (Table 3.1.3-6). The major peak in copopodit %d adt:M abundance usually occurred April through September. Low abundances, especially of copepodites, occurred dttring winter (Figure 3.1.3-1). In 1987 adults vere not observed in May and November, though copepodites were still abundant. In general, temporal abundance patterns in 1987 were typical of previous years (Table 3.1.3-7). A more detailed description of the life history of Calanus Ifnmarchicus and other selected species is available in the 1984 baseline report (NAI 1984). 98
- 7
. 7 8
560 535 5, 3, 6, 008 67 1 1 3, 243 60 9 01 2 677 37, 834 588 27 8 9 9 1 841 1 1
- 1 4 %K 5O ,
- 9OT 870 RR 966 805 425 953 RBO 4 1 7 1 1 44 62 1 96 548 EAP WEE 8 9 8, 0, 3, 5 8,1 7 35, 7 0, 2 OSR 1 891 1 1 2 L 5 - TE
' DAN N I .
ANL 465 585 345 7 08 484 OE 3 369 561 99 460 984 RTS 8 6, 5, 0, 5 6,1 3, 57 1 4 6,1 EKA 9 - , - PNB 1 21 3 2 1 2 1 PA 1 5 ULK PO
'D 0 O -
N0R 628 665 022 581 1 26 A2B 2 546 862 41 237 550
) RE 0A 8 9 7,3,6 1 3, 5 45, 6 0,2 3 CS 1 43 1 2 2 mA 3 M -
0 0F7. 0O8 962 645 022 746 045 1 9 1 5 91 1 31 49 561 007
/.oIE S1 8 9
1
, 8, 2, 1 8 5 1 4, 41 ,
D 1 333 1 2 NCN 1 5 ( EA P ES4 ' C 8 343 887 232 228 289 ND9 0 589 392 47 521 584 AE1 8 7, 8, 2, 381 5 1 2, 22, DT - 9 NC8 1 904 1 1 UE7 1 9 BL9 AE1 S . N , 496 922 261 235 058 AF2 9 1 1 9 222 27 47 4 49 EOP 7 6 2,4, 17 2 35, 1 M 9 , SN 1 691 2 CTO I I I 2 RMT TIA ELT 948 7 46 163 424 41 5 M S 8 91 6 642 40 005 524 OE 7 9, 6, 5, 7 6,1 4 40, 1 5 - ECD 9 GNL 1 81 1 4 3 EE 5 LDI AIF - UFR N N N N N NNA ALL ALL ALL ALL ALL NOE ECC ECC EC ECC ACN MUL MUL MUM MUL E C C. MUI
. e 6 aa
- s s sv 3 u u or S c c na a 1 E i i il n
. G h h pt as 3 A c c s ss ce E
T S r as a r a n mo ep i g ra L E me m e t et B A F I nt ii i n a m pd en aef ms T L fd f s sa
/ o se si S sp st ua ne il E ue ul nv os syl I np nu ir ge C ao ad ca no ml E
P l c a l a a rl a aZ r oa e S C C C C N
,e
CALANUS FINMARCHICUS f 6-COPEPODUES " i
/*'., -.
gg / ,, w= g ..,......,,.,
- a. m ,, ..
Wh 4- /. '.* QW
- 22 .
l .
<O Q /
2E f
..***=... '
$D 4 0 3-
/
8 / _ ALL YEARS MEAN
.a e 2- ',/ ,
... .. ige 7 uggs 1- . . . . . . i i a i e i JAN FEB MAR APR MAY JUN JUL AUG SEP OCT FO/ [E l
l 1 6-ADULTS j
~
5-E en ' W tr. - 0w 4
-, j m F-uW
- l f / **. ..* '., i oo 3- . / .
,'...- .. ,, .. 1
,',- ,a".,'
i z3 / 1 1 8g
. . . , '; % l .,
2 / .\ l 0@ Oo ,/*
\. .
l
/
j- ',
. .. / _ ALL YEARS MEAN .,
***-. 1987 MEAN
- i l l \li '. . . . * * * , , , .
0 . , . . , i i i i i l JAN EB MAR APR MAY JUN JUL AUG SEP OCT PC/ CE i Figure 3.1.3-1. Log (x + 1) abundance per 1,000 cubic meters for l Calanus finnarchlcus copepodites and adults; monthly mean and 95% confidence interval over all years 1978-1984, 1986-1987 and monthly means for 1987. Seabrook Baseline Report, 1987. 100
S N O 8 F S 7 I O R S A E P 0 I K M 8 CO O EO C PR E SB L A 7 DE P 8 I ES T T L C U E . M L7 1 E8 8 S9 1 R OD FN 3 8 A S R4 A8 E9 Y1 2
- 8 G8 N7 O9 M1 4 A 8 2
EP C NN S AO N S S S II N N N RT F 5 7 5 1 3 AA 6 2 6 7 VT 0
. 5 S 1 0 0 F 3 OD L
SE I I 885 762 67 3 SF S 7 64 494 886 066 YR . 023 056 730 LA S 720 AE . 67 1 02 235 482. 90 7 52 7 75 NN7 22 33 45 89 292 ) A 8 22 1 2 1 T9 s YA1 A d 0) 1 WN , f d 7 85 7 85 7 85 i o 0. 0
- OT 7 8 7 8 7 8 7 85 7 85 r 00 ETR 1 1 1 1 1 1 7 8 7 8 e NKO 1 1 1 1 p )
20 ONP 1 p5 AE FN g 0 FLR OP OO n) 2 p I i50 ( 0E ET S0N CA SRL SRL SRL l 0 p .> 0 1 TZI RI ROA ROA ROA SRL SRL m0 .tn LOL UR ART ART ART ROA ROA a URE OA ERO ERO ERO ART ART s> p0 a SCS SV YET YET YET ERO ERO ( c EAA YET YET yp 2 tf i RMB l (5 ni e h 0 an
. s s aa t t . cg 7 u c u sv or nn0ii - c oa( f s mc 3 i i na a i . h h il n - it ny 1 c c s pt as if n gl r r a ss ce miaih 3
as a n mo ig encsg ne nt n e ep t ra s gi if yh i E n a et L ii fd i c pd en ms ae nsil o nh y B o f sa t ggr A S sp s se f d oiie T E ue st ua ne si eNSHV ul nv il I np nu os s s C E ao l c ad ir ca ge no yl a= = = = B l a rl ml P S a C a a aZ r oA
- S*
N C C e C #
- o"
l A comparison of semi-monthly abundance among stations in 1987 indicated no significant difference (Table 3.1.3-3). Local hydrographic conditions and organism behavior are such that stations do not host independent holoplankton populations. Carcinus maenas 1 i Carcinus maenas larvae first occurred in May and were present l through December (Figure 3.1.3-2). Larvae were most abundant between June and September and declined sharply in abundance during October in most years. Stage I zoeae were abundant from mid-June to early September, following peak abundances of gravid females in Hampton Harbor (see Section 3.3.7). In 1987, zoene I, zoose II and zoese III larvae were most abundant in late July, while zocae IV and megalopa larvae were most abundant in mid-August. The extended period of abundance for all lifestages suggests that spawning and recruitment from local and regional adult populations is asynchronous. Abundances of Carcinus maenas larvae were similar at all stations in 1987 (Table 3.1.3-4). Since adults are common in-shore near all three stations and hydrographic conditions typically do not separate stations, the above observation was not unexpected. Crangon septemspinosa Spawning in Crangon septemspinosa typically commenced in April with Although zocae and post-larvae abundant through November (Figure 3.1.3-2). larvae, including zoese I, were present year round, peak abundances in June through September were two to three orders of magnitude higher than abundances observed November through May. In 1987, peak abundances July Overall, annual mean through September were typical of previous years. abundance for 1987 was well within the range of this study, 1978-1984 (Table 3.1.3-6). A comparison of semi-monthly mean abundances indicated no significant difference between years for Crangon larvae and post-larvae i 102
)
_ N O 7 _ S F I O R A 0 S P 8 E M I K O _ CO C EO PR E 7 SB L 8 A P _ DE I ES T T L C U 1 E . M 8 L7 E8 S9 1 R 3 OD 8 FN A S R4 A8 2 E9 8 Y1 G8 N7 4 O9 8 M1 A ,
" 2 EP C
NN S S S S
- AO N N N N
- I I 5 5 1 3 7 RT F 7 6 2 6 5 AA . . .
VT 0 1 0 0 3 S F OD L SE 885 7 62 67 3 886 066 I I 764 494 023 056 7 30 SF S . . . . . . . . . . YR S 720 1 02 482 752 77 5 LA 67 235 90 89 292 ) AE 22 33 45 22 1 2 NN7. A 8 s 1 0) d 0 T9 o YA1 i 0 A f 7 85 7 85 785 785 7 85 r WN , d 7 8 78 7 8 7 8 7 8 e 2
- OT 1 1 1 1 1 1 1 1 1 1 p )
ETR NKO g 1 p5 0 ONP n) 2 AE FN i50 FLR OO l 1 OP I p 0.> 0 0E ET SRL SRL SRL SRL SRL m0 S0N CA ROA RO! ROA ROA ROA a p0 a TZI RI ART ART ART ART ART s> ( LOL UR ERO ERO ERO ERO ERO 2 URE OA YET YET YET TET YET yp t SCS SV l ( 5 ni EAA h 0 an RMB e t t . c aa nn0ii s s sv oa( f s u c u c or na mc i 7 a - i t ny
- i i il n if n gl 3 h h pt as miaih c c s ss ce encsg 1 r as r
a a mo i g s gi n ep ra if yh 3 me m e t et nsil E nt ii i n a m pd en ms aef o nh y t ggr L fd f s sa d oiie B sp o se si eNSHV A S st ua ne il s T E ue ul nv oa s a= = = I np nu ir ge yl B C ao ad ca no ml # S*
- E l c l a rl aZ oA N
- P a a a r e S C C C C N o~
l '
A comparison of semi-monthly abundance among stations in 1987 indicated no significant difference (Table 3.1.3-3). Local hydrographic conditions and organism behavior are such that stations do not host independent holoplankton populations. Carcinus maenas Carcinus maenas larvae first occurred in May and were present through December (Figure 3.1.3-2). Larvae were most abundant between June and September and declined sharply in abundance during October in most years. Stage I zoeae were abundant from mid-June to early September, following peak abundances of gravid females in Hampton Harbor (see Section 3.3.7). In 1987, zoeae I, zoeae II and zoese III larvae were most abundant in late July, while zoeae IV and megalopa larvae were most abundant in mid-August. The extended period of abundance for all lifestages suggests that spawning and recruitment from local and regional adult populations is asynchronous. Abundances of Carcinus maenas larvae were similar at all stations in 1987 (Table 3.1.3-4). Since adults are common in-shore near all three stations and hydrographic conditions typically do not separate stations, the above observation was not unexpected. Crangon septemspinosa Spawning in Crangon septemspinosa typically commenced in April with zoene and post-larvae abundant through November (Figure 3.1.3-2). Although larvae, including zoene I, uere present year round, peak abundances in June through September were two to three orders of magnitude higher than abundances observed November through May. In 1987, peak abundances July through September were typical of previous years. Overall, annual mean abundance for 1987 was well within the range of this study, 1978-1984 (Table 3.1.3-6). A comparison of semi-monthly mean abundances indicated no significant difference between years for Crangon larvae and post-larvac
]
102
CARCINUS MAENAS 6-
- ALL YEARS MEAN
...~. 1987 MEAN
@ 5-I , , . . . . * "' .....,
4~ .
,. ]
E
/' '
3 5
- a. :
l w '
$ 2> / I.
e o 4-
.u..... ...
0 -- $ d E $ f a 4 $ $ % 1 a 8 E $' $' -$ $' CRANGON SEPTEMSPINOSA
. ALL YEARS MEAN lfi 5- ... .. 1987 MEAN O
s 4- . g .....".,,,., g r ,. [e 3-5..,.
~ $ 2- /
g , 8* a g 1- i [' 0 , , , , , , , , ' ,' ' ' z T > 2 J k $ 5 b l Figure 3.1.3-2. Log (x + 1) abundance per 1000 cubic meters for Carcinus maenas larvae and Crangon septomspinosa zoeae and post-larvae; monthly mean and 95% i l confidence interval over all years 1978-1984, l 1986-1987 and monthly means for 1987. 103 l 1
l (Table 3.1.3-7). There was no significant difference in Crangon abundance between stations in 1987. 1 Neomysis americana ) Neomysis americana was present year round in the macrozooplankton a but was most abundant September through April (Figure 3.1.3-3). The annual cyclo was slightly bimodal, with depressed abundances May through August. 1 i Lifestages of Neomysis americana have historically exhibited distinct ' seasonal patterns (NAI 1985b). Immature and mature individuals were most abundant in winter while ovigerous and larvigerous females were most abundant in April. Juveniles were most numerous in late spring and fall (Figure 3.1.3-3). In 1987, unusually low abundances were observed in September and October, largely due to lower than normal numbers of juveniles and immature adults. A multiple comparison of seel-monthly Neomysis abundance indicated that 1984 was significantly higher than all other years while 1979 was significantly lower than all other years in this study (Table 3.1.3-7). In 1987, Naomysis mean abundance was not unusual, ranking fifth among the eight years involved in this study. In 1987, as in previous years, Neomysis americans was more abundant at Station P2 than at Station P7. As noted in previous baseline reports (NAI 1984, NAI 1986), this difference may be related to the different types of substrate underlying each station. Recruitment from nearby Hampton Harbor may also have contributed to high abundances at Station P2. Station P5 was similar to Station P2 in terms of abundance, though statistically neither was significantly different from Station P7 in 1987 (Table 3.1.3-4). 104
z - S P E n oB
$ ,z T
E H C B U aB : C - S
- O
- s:: ..** .* .
* =
_ M . R E oe -
~
_ P a #
.' .. . / .
E
- C .
r N ., A ot * - _ D t * ; t N U B
.q
^
.' .l
- : (.
A G - I O O L o - - - - - - - - - ~
- N B R R Y L G A
J E F A M P A A M N U J U J U A - T C O E a s< goc
" R s
oo mo T N E C mo R E P ao o to s e N A J B E F R A M R P A Y A M N U J L U J G U A C - T C O
*tOo .
M"o,E , 'f. m"0SomDO* men '*oo 3 weu- ^X + i. L. o n
%2oSN4Am g ,AOSnh- $atx~w 9 e i .. @
+D,ren4m~ { n D ~ wm$m wowos s .
,l- .o 9OatxrM r m >%0n >4e ' u muo. se v iO +r OU O>+i s e l- m e u"2";*O3x 0.aec 3
- o h .S21kOba" 3s o0O=wecu m mr s:eantm,~W.-amcml.
e n * * - 3 o ummUnOOx " .>>+oo lxe3ntr- eC Ho"
3.2 FINFISH 3.2.1 Ichthyoplankton 3.2.1.1 Total Community Nearfield (P2) Ichthyoplankton data collected from 1976 through 1987 were examined for temporal (seasonal and year-to-year) patterns in species assemblages by discriminant analysis. Species composition and frequency of occurrence at the farfield station (P7) and at the discharge station (P5) were compared to data from P2 to detect any differences in ichthyoplankton communities among the sampling areas. Common names recognized by the American Fisheries Society (Robins et al. 1980) are used for fish species in the text. The common and scien-tific names for every species collected from 1975 to 1987 in the Seabrook ichthyoplankton and adult finfish programs are listed with their relative abundances by gear type in Appendix Table 3.2.1-1. No newly-recorded species were encountered during the 1987 surveys, although fourspot flounder, which previously were only captured as adults, occurred in ichthyoplankton samples for the first time in 1987. Temporal Patterns of Nearfield Fish Egg Assemblages Numerical classification of 1976-1984 data had shown that the species composition of fish eggs was highly seasonal in nature, with dif-ferent species occurring at different times of the year and generally the same seasonal succession repeating each year (NAI 1985b). The basic pattern over the 1976-1984 baseline period was summarized by nine groups of samples, each characterized by a particular assemblage of species occurring at a part.icular time of year (Table 3.2.1-1). I 107 )
I I T R D 1 A ( E N /. - T G A O _ S E N M t D I E r I e F d lt A n u E o B k l k c f: :o T S o A G d l d G d i d D E e a e a a E ch ct h T H i / i w/ C S d ad a od I o l o l l o E F c p c p l c L e D T c n c n /y ic C N i k a i a A t c ct c r t S M n o i n i e n G I a l r a r n a G t l l el e n l E R t o mt ( m u t H D A P A A A C A S . I 7 F 8 9 C 4 7 3 4 A B C F 1 E 3 9 3 4 A B C 0 O . D 2 7 0 1 2 4 A B C S T 1 8 1 3 4 A B C R EO P P V% O 9 6 9 0 2 3 4 A B C M E N 2 1 3 4 B A R 0 3 4 S 1 7 8 1 3 4 B E
~
F N T 4 6 2 O I C 3 9 1 L O 2 E 1 S S E A G B P 4 A E 3 L K S 2 BOO 1 DR S B S G 4 S A E U 3 A E L A 2 S P 1 L M A A N . S L 4 O 7 U 3 S 8 F J 2 A 9 O 1 E 1 S N R O N G E I U % NB O T U J 2 1 MD B A C I E R Y 4 OD D T S A 3 M2 1 3 A H I 8 0 4 C G D 7 0 1 2 3 4 A B C U . S O R 4 K R F 3 1 2 4 8 9 3 4 A B E H A 2 4 A 6 9 0 3 A B C ET 1 7 9 0 1 2 4 A 8 3 B l 3 B 6 G 7 R 4 G 9 A 3 8 3 4 A C I 6 8 9 0 O1 I M 21 1 2 3 A B C 7 8 3 4 A B C 2 3 4 B C A Y R N A B 4 6 9 2 3 4 B O U E 3 I N T A F 2 1 A B 1 8 6 Z MBB C U J B I G M 4 7 4 A B 0 3 R N A 3 1 2 4 A B T I J 2 9 4 A B 3 S R 1 7 2 4 B 0 1 I U D D 1 R k
- E c d l 1 r o f o i 2 E l
I l l c a G H o R G e
- - /t 3 A - p E N c G e r w L L - T I i N c e o L d I i n l E E A o N
I P l R a a n l B D F C P" l u e A S N S P S P c y T S . . . A 1 2 3 l l
T N 0 9 1 1 3 9 3 1 _ E 1 G E 0 E N D 1 G A O
/
6 2 2 1 9 8 8 2 3 7 2 3
' EN I t r r r
_ e e e d d d n n n u u u o o o l l l _ f f _ d f S l l G l l i G i e i E a r a a t e t t H w k w w S o c o o l _ I l a l _ F l m l l e e n e e T y c y
/y a N / i / p A r t r r w N e n e e o I n a n e e n d k n n 1 n l n k G u t u a a u i D C A C H H C W C 4 E 3 D 2 1
V 4 O 3 N 2 1 T 4 C 3 O 2 1 P 4 E 3 4 2 S 2 3 A 1 7 8 2 A S G 4 0 1 2 3 A E U 3 6 7 9 8 3 4 A B C L A 2 1 8 2 3 4 A B C P 1 7 9 0 4 3 A B M A S L 4 8 1 3 4 BC U 3 6 7 9 0 3 4 B 2 A A C F J 2 8 9 0 1 3 4 A B C O 1 7 3 4 A B 2 C N O N 4 0 3 4 B A C I U 3 C 8 9 3 4 A B r f S 2 1 C 6 7 0 2 3 4 A B t 1 8 1 2 4 A B C 9 3 B I R Y 4 7 8 O 4 A B C T A 3 6 9 I 2 3 3 4 A' B C S M 2 9 A B I 1 D R P M A 2 1 R 4 A 3 M 2 1
)
BM E F 2 d 1 e u n N i A M t J 2 n 1 o C I
/
. - - r 1 l l el
- i i n i 1 al a n a E / t e / t u t 2 G G r w r R r w R c w A N e o e E e o E - o 3 L I n l k M n l e f f e l E R n l c M n l k a k l E P u e a U u e a t a e L D S C y m S C yh S M y B S A S . . .
T A 4 5 6 wO*
M D 1 h g 0 / h t e E N . g G A O u gd E N o n o M f r i C h n - t i e 5 a c t i g 8 n a 9 ol n 1 , cP i 4 l m 8 s g k o 9 a n S g c g r 1 i G n o n f - d r G i g r g i 6 e p E H l n k i ct d r i t n l k c 1 3 l
. es 7 i S 9 f -
1 i r S oi a d i o - p s e I r h e oh r 4 m m s t F w b e c w 2 a o a n d r n d S rl i T r c u o p a c c r s f cW N ai i i a e A M e t b n f w
/ o t t n n h e t a n s e e e r h I
T e r a ed a a e r d o l e t p w k u l k n l l k u i O a ot ai t t a o = t m D M F A MW A A M F a a) n 4 c s8 i i - n k f r1 i ei o C 4 e s f s t E 3 N s e n D 2 a r t o 1 d l a a c n c e y d a t d _ V 4 ,la O 3 C n y a _ N 2 1 A B C 3 c 2 i o r _ A C i a , - - r .t u 6 T 4 6 e s c n 8 C 3 3 C 3 4 A B C 1 m n e a 9 O 2 4 C 0 4 A B u ol J 1 _ 3 B s n i l _ 1 8 9 1 3 4 C A B 7 e t of d _ t n c c o n a o n P 4 E 3 6 0 1 3 4 A B 9 3 A B C C d u f k d f o e , S 2 9 1 B 4 C = e 1 0 3 4 B C 3 a n i s t t w 8 e4 9 _ b a gt 1 S G 4 C 4 B k n i s E U 3 e s i d r , _ L A 2 e a m i 2 _ P 1 C' W wit f 8 M r s 9 A , s c a e1 _ S L 4 5 e sl h U 3 1 g i t , - F J 2 - ad = 7 O 1 9 l d 7 b yl e9 _ N s mb ot 1 _ O N 4 e e b c I U 3 T J 2 t s s m e s T a s e y l r I 1 d a g sl a B I a o e R Y 4 = ol t b : c T A 3 2 m e s e S M 2 4 a t e h I 1 k 8 s a l t D e9 s d p R 4 N e 1 a g a i m n P 3 h 4 n s A 2 , g8 i 1 6 u9 l , g
- o1 p e a8 R 4 1 rh - ml l 9 s 6 a p b 1 A 3 s t 79 s m m M 21 e a e t 6 1 e x s n i a 7 l e s d 9 e g B 4 A 1 h n r )
E 3 = t i o g 8 d - F 2 m sF g9 _ d 1 A 1 o o e r t a u k f n . _ n M 4 e i s7 c r _ i A 3
&e s t 6 o t J 21 n 1 ed n 9 l e A
l e e1 l yi _ o , p i s = o C h mf eC P et ( . t ai r n s s p .d L L o s e6 o - 1 L L mf a r 8 C n e e ol 9 -
- A A - n
_ 1 F g g a h cl 1 _ F - ct o = e E - n g - n p g a n eb B t g s _ 2 G R i n R i w n e e r m _ A E - l i E / l o i m e y , i l h _ 3 L t ek t I ek d L - t e n n w s 5 W b E L B
?
Mk L a o h ci Mka I c n oi L d i k A oh a i g h i 7 h 9 l e 8 - . E S H r w S H r w F C w h t s 6 c1 l s x B S i s 9 a = a s A S T A 7. 8 9 N A 1 E A F
' b C
Ho
- l. j'
a.
.i Two of the groups (8 and 9) had lower within-group similarity values (NAI 1985b) and lower numbrs of samples than the other seven groups. 'They were characterized by relatively low abundances of s few species that occurred during the fall (NAI 1987b).
Discriminant analysis agreed fairly well with numerical.classifica-tion analysis in the recognition of the nine seasonal assemblages of eggs. Discriminant analysis assigned 196 of the 219 samples (89.5%) to the same group as that assJgned by the cluster analysis. -The seasonal groupings..of samples recognized by discriminant analysis included late fall-early winter-(Group 1), winter-early spring (Group 2), spring (Groups 3 and 4), summer (Groups 5 and 6), late summer-early fall (Groups 7 and 8), and fall (Group 9). Table 3.2.1-1 shows which samples were classified into each group, and what the dominant species and their densities were within each group. l The late fall-carly winter cod pollock assemblage ~(Group 1) appeared in 1987 from late November through the end of December. The Group 1 assemblage is characterized by moderate numbers of Atlantic cod and pollock j eggs (65 and 14 per 1000 m , respectively), with very low abundances of other' species ($ 0.3 per 1000 m ). In previous years most January samples were also classified into Group 1 by both cluster analysis.and discriminant-analysis. The January samples from 1987 had a species composition similar to that of previous years but these samples were excluded from the analysis because of low densities. 1 The second seasonal group, a winter-early spring plaice'and cod /. haddock assemblage, occurred in February and March in 1987, which was typical
' of the baseline years' pattern. Pollock eggs were replaced by American. '!
L plalce eggs as a dominant species during this seasonal period. The spring plalce-cunner /yellowtail assemblage (Group 3) was present in April and May during 1987, similar to previous years. This group was characterized by an increase in the number of abundant species.3 In.1987, 3 fourbeard rockling was the most abundant species (295 per 1000 m ), followed by American plaice and cunner /yellowtail flounder, with relatively few 111
3 Atlantic cod / haddock eggs (7 per 1000 m ) compared to 1976-1984 (NAI 1988). Most of the cunner /yellowtail flounder eggs at this time of year, while not identified to species, are assumed to be yellowtail flounder since this species begins spawning in March, while cunner do not typically begin spawning until June (Bigelow and Schroeder 1953). The spring cunner /yellowtail flounder-mackerel assemblage (Group ( 4), was present the last two weeks of May and the first three weeks of June in 1987, which was similar to the previous baseline summary period (1976 through 1984). It exhibited high abundances of cunner /yellowtail flounder and mackerel eggs. Fourbeard rockling and windowpane eggs were also abundant. A very abundant summer cunner-hake assemblage comprised the fifth group of the 1976-1984 baseline period. Generally, the Group 5 assemblage occurred from early June to late August or occasionally into September. Cunner /yellowtail flounder and hake eggs dominated egg collections during this period. Most of the eggs identified as cunner /yellowtail in these summer sampics were probably cunner because yellowtail flounders spawn primarily in the spring whereas cunners spawn during the summer (NAI 1983b). Windowpane, Atlantic mackerel, fourbeard rockling, and Atlantic whiting eggs were also abundant in this seasonal group. None of the sample collections in 1987 were classified into this group. A second summer group (Group 6) was a hake-cunner /yellowtail flounder assemblage. During the 1976-1984 summary baseline period, this assemblage occurred from early July to mid-September. Only four years were represented (1978, 1982, 1983 and 1984), with the majority of samples coming from the latter three years. During 1987, this assemblage first appeared in late June and was present through the end of August. This assemblage, which temporally overlapped the fifth group, usually had lower abundances of cunner /yellowtail eggs and higher abundances of hake eggs compared with Group
- 5. This assemblage was further characterized by moderate numbers of window-pane eggs. Other species also exhibited a decline from early summer 112
) 1 i abundances. In 1987, cunner /yellowtail flounder eggs were very abundant I during the late June through late August period, while hake eggs were moder-ately abundant (NAI 1988). The discriminant function analysis classified i these samples with Group 6 rather than Group 5 mainly because of the absence of Atlantic mackerel and Atlantic whiting eggs during this period. These two ; ! species are often fairly abundant in July and early August, and are charac- ; teristic of the Group 5 assemblage. In 1987, however, mackerel eggs last l occurred during the third week of June, and whiting eggs did not appear until the last week in August. I The seventh seasonal group, a late summer-early fall hake-rock 11ng-whiting assemblage, was composed of samples' collected from September to mid-October during the 1976-1984 baseline summary period. The only years not ; l represented in this assemblage were 1977 and 1982. During 1987, this assem-j blage occurred during late August through the third week of October. Hake, although diminished in abundance in comparison to its density in Group 6 samples, still dominated egg collections. During 1987, as in the past, other species continued their gradual seasonal decline (NAI 1988).. I A small summer-fall group (8), represented by only three samples l l during the 1976-1984 baseline period, temporally overlapped Groups 6 and 7. ; ) ! This egg assemblage contained most of the taxa occurring in Groups 6 and 7, l 1 but densities were generally lower. Four sampling dates in 1987 were classi- ) fled with this group. A small group of fall samples comprised Group 9. This assemblage was characterized by low to moderate densities of Atlantic cod eggs, along l with modest numbers of eggs of species that are primarily late summer l spawners: hake, Atlantic whiting, and fourbeard rockling. The samples from late October through the third week in November in 1987 were classified with l this group. I I l Overall, the classification of the 1987 samples of fish eggs by ,i discriminant analysis followed a similar seasonal pattern compared with both numerical and discriminant classifications of samples from previous years, i 113
l l with the exception of increasingly more importance being assigned to two j minor groups (8 and 9) consisting of late summer and fall samples, and also .k the absence in 1987 of the major summer assemblage represented in previous
. years by Group 5. {
l 1 Atlantic herring, American sand lance, and winter. flounder, which i
.{
are important components of the larval assemblages discussed below, do not ] appear in the baseline analysis.of fish eggs because these species have j$ demersal rather than buoyant eggs. These eggs are rarely, if ever, collected in oblique tows through the water column. Temporal Patterns of Nearfield Larval Fish Assemblages Numerical classification analysis of fish larva abundances at the' nearfield station (P2) during the period 1976-1984: revealed the same high degree of seasonality as was observed among eggs (NAI 1985b). The seasonal succession of larval assemblages can be summarized by four major' groups, fall-winter, winter-spring, spring, and summer, each containing from one to three subgroups (NAI 1985b). Discriminant analysis placed each of the I 1985-1987 samples into one of nine seasonal assemblages (Table 3.2.1-2). - ( The first major group, fall-winter, consisted of two larval assemblages (Groups 1 and 2). Atlantic. herring larvae were the dominant f species in Group 1, which occurred from early October to mid-November in the 1976-1984 baseline period (Table 3.2.1-2). Only a few other species were 1 present during this period, all in very low abundances (NAI 1985b, 1986, j 1987). During 1987 the Group 1 assemblage extended into the third week.of January. Group.2 (late fall-early winter) was dominated by_pollock and ! Atlantic herring, with the latter displaying decreased abundance from the collections earlier in the fall. 114 i
I E E 0 1 1 - T A T S MD C E N G A O E N 1
/.
D L M E E I F R A E N E T A e a - A V c e _ R n n D A g g a a E L n n l l T i i C H r r d d E S r rd n n d L I e e o a a o L F h h c s s c O n n c C T c c c a _ N i k i i aii E A t ct t c ct f A N n o n n i i n l V I a l a a r r a i R M l l l l e el a A C t ot t m mt n L D A P A A A A A H S . I 7 F 8 C 4 B 7 2 3 4 A 8 9 E 3 9 3 A B 0 F 1 D 21 7 0 1 4 A B C 2 O , B C 8 3 4 A 1 S T E R V 4 A B C 9 0 L 3 4 L O O 3 4 A B C 6 9 I P *. N 2 2 3 4 0 A B C M E 1 7 1 3 4 A C A R S E T 4 6 2 3 4 A B C F N C 3 9 0 1 2 4 B C O I O 21 4 A B L 4 B b E S S E A P 4 G B A E 3 S 2 L K 1 BOO DR S G 4 S B E U 3 S A L A 2 A E P 1 S M L A A S L 4 N . U 3 O 7 F J 2 S 8 O 1 A 9 E 1 N S O fM 4 R I t 3 G E T J 2 T N O E t B 1 MD I R A C Y 4 E T A 3 D D S M 2 N I 1 2 A C A H D G a U R 4 4 S O P 3 B C K R A 2 4 E H 1 E T N 6 R 4 G 7 A 3 8 N 9 M 21 O 1 7 N A Y N O A U R B34 F 2 A 8 4 C GC I N 1 4 6 1 2 A B T A U J B N 4 7 0 4 A B C 3 I G A 3 C A B 9 0 R N J 21 A B 9 3 C T I 7 1 A B - 2 C S R I U D D 2 R
- E 1 T g
N - 2 E I k g - G n W c n R R G 3 A L i - oi E 'e E N L r L l r I d c I I E E L r L l r N n n N R L A e A o e I a a I P B D F H F P h M S l M S A S T S . . . . A 1 2 3 4 we\n
y C T m
)
I I R S 0 5 7 5 S 5 1 3 4 7 9 T N 0 2 4 2 S 4 4 3 1 7 2 E E 0 4 4 MD 1 ( E N G A O E N
/. -
Mt
) )
p p s p p s E s s A e i i V cn r r g n = R a a A a p p y e i g L l i ri l n L eL n c k i H d ( d ( n i ct S n n a a oi I al s u sh l rh F s e n h e o e s p l h d w T N A M I n n s a u i c gf i rk i l f sd n i e a rf t c el ai t i i r r et mt n r a r c ai n d e u M e c a n ad e n ul n ( m o n i n a m u ot C F A i D A R S M SR A t n o - c C E % D 21 V 4 O 3 N 2 _ 1 T 4 C 3 O 2 1 - P 4 1 E 3 C S 2 9 3 A C 1 7 3 4 C S G 0 3 C E U M 6 7 9 3 4 L A 2 8 3 4 P 1 7 9 0 3 4 C M A S F L 4 U 3 J 21 9 4 8 1 3 4 6 7 9 0 8 0 1 3 AB C E3 4 O 2 B 7 3 4 A N O N 4 4 A B 0 3 I U 3 8 9 4 A B 3 C - T J 21 r t 6 8 97 10Z I3 4 2 A3 B 4 A ( BC B I R Y 4 7 8 0 4 A BC T A 3 6 9 1 2 3 3 4 A BC S I M2 1 8 9 0 3 4 A B C 4 7 0 3 B D R 4 8 B 9 3 A P 3 9 0 1 2 3 4 6 A 2 8 3 8 - 2 7 9 0 1 2 3 4 B C R 4 8 3 4 A B C A 3 6 9 0 1 2 3 4 A B C M2 1 1 2 3 A BC 8 3 4 A B C B 4 6 9 O 2 3 4 A B I E 3 1 4 A F 2 0 3 B d 1 C e u n i N A M 2 t J 2 n 1 o C I
. - l 2 e e - c n - h 1 n n r s g E - a u ei - n 2 G R G l g G rd f R ri A E N N e nl E el 3 L T I d k I t ui I n k E
L B D I N R n c P a o R n o a P i l n Mnu I o c W S S r S W f s S C r B S A S . . . T A 5 6 7 a wio
!illi ( ll (rI
E E 0 r g a I N D 1 h n l E N /. t g i G A O u n e E M o i c M ( r a n h t a - t n L _ o G cd t n 9 s a 1 , aS d 4 - E m 8 d r A o 9 e e _ V g r 1 i t _ R n f - f n A i 6 i i - L l . s 7 s M k r 1 e 9 s H c e 3 l 1 a e S o d - p l h I r n 4 m m ct _ F e u 2 a o _ d n o S r e g _ r r a l s f r n , *h a p f e e i A r e w r t . s w n M e b o h e a n e ) i 1 n r d c e n d oi l a 1 n u n t k n p 8 t N E u oii a u = t m - n D C f M M H C a a1 o 4 c i s s c k f r ed ei ot n C e s f a a E % M s d . D 2 a r t , d 1 d l a 6 e n c e y 8 zy a y r9 V 4 ,la a 1 l O 3 n u a N 2 3 c o n d n 1 2 i
.it Ja a n a
- r 6 e s c a T 1 m n ef , x C % A u ol o5 a C 2 3 C s n i l 8 t 1 8 1 3 C e t ok 9 t n c c e 1 l P
a o nu f e l 0 6 3 d w , a E S 21
% 4 9 2 %AA C = es d f o t 8 1
f 8 A 0 2 t t s 9 o 3 a n i r1 b a g i l S 1 A 2 4 k n i f , a I G U % 8 A C e s i d 7 t I A 2 1 2 A C B e a m e7 o P 1 A B N w i t h 9 t M r s t 1 A , s c a e S L B 5 e s l n s h U % A B C A 1 g i i r t F J 2 - a d = a O 1 C 9 l d e f b y l e y o N s mb ot O C e e b c e % I N U % t s s m eh 5 T J 2 a s e y l t U 1 d a g s l t B a o n s I = ol ci a R Y 4 t b e T S A 3 M 2 2 4 e m es s e t e g l I 1 k 8 s a l a t D e9 s d p l a e 1 a mb R N g a m e P % h W n s es . er A 2 , g E i 1 8 u 9 l ,s 7 w
- o1 p e a8 1 r - m l 9 s R 4 h 6 a p l 1 e A 3 s t 7 s m a i M 21 e 9 a v d t t 6 1 e x r n i a 7 l e a a s d 9 e g l n 1 h n r 2 e
)
B E % = t i o g 8 d . F 2 m s F n 9 s d e 1 1 o o i 1 r n e r t a a l u k f n . r s e p n N 4 e i s 7 e r m m i A 3 e s t 8 H a a t J 2 N e d n 9 - e c s n 1 l e e1 k yi o , p i s = c r4 C h m f eC o et 8 ( t a i r l h e9 n s s p , l t m1 o s e6 o o - L m f a r 8 P n e 6 2 L ol 9 - i g 7
- A h cl 1 r 9 1 F g ct o = e e e1 E - n a n e b B t g s 2 G A
R r E e R i E l e e r m m e y , i l h o n a o n 3 L f n 1 k n n w s 5 M b w B 9 f n 9 f c i g 8 - m d E 1 U u U o h i 7 h 9 l e a e L D S C S R t s 8 c1 l s x s B S i s 9 a = a s a a A S . W bA 1 EC A F aT B T A 8. 9 d e wew Ii l
e American sand lance larvae dominat'ed the second major seasonal period, winter-spring, consisting of Groups 3, 4, and 5 (Table 3.2.1-2). 1 Group 3 samples were characterized by moderate abundances of American sand-
. lance'(199 per 1000 m ) and relatively low' numbers of a number.of oth'er 3
winter species (s 6 per 1000.m ), .This assemblage usually occurred.from some time in December to about mid-February. Two samples from 1987 were classi- , fled with this group. The Group 4 assemblage consisted of four samples in winter'and spring of 1976-1984 that had.Iower densities.of larvae and fewer numbers of species than in Group 3, with sand lance still being the dominant i l species. 'An' unusually large number of samples (six) from 1987 were classi-fled into this group, an indication that densities on those dates in 1987 i were lower than typical for most years. Group 5 consisted of a large number of late winter and early spring samples characterized by high densities of 3 American sand lance (425 per-1000 m ) and moderate densities of rock gunnel 3 3 (47 per 1000 m ) and snailfishes (25 per 1000 m , primarily Liparts cobent). ! 1 This larval assemblage usually was present approximately from mid-February to late April. Six dates from early February to early April in 1987 were 1 classified with Group 5. I A spring larval assemblage was usually present during May and' June in 1976-1984. These samples comprised the third major seasonal group, Group
- 6. The spring group, as in previous years,'was characterized in 1987 by moderate numbers of winter flounder, snailfishes (primarily 4/ paris atlanticus), radiated shanny, and American plaice larvae. This assemblage ,
I was present from mid-May to mid-June in 1987. The fourth major neasonal group, summer-early fall, consisting of Groups 7, 8 and 9, typically lasted from early July to early October. Group 7, the largest of the three groups, was mainly characterized by high densi-ties of cunner larvae and moderate densities of fourbeard rockling and Atlantic whiting. Witch flounder, Atlantic mackerel, windowpane,'and hake l u larvae were also important in these samples, which were primarily from July, August, and early September. Group 8 is distinguished from Group 7 by lower l densities and fewer species, with cunner being the only important species. 118
i (. k { l i ! 1 L
.]
1 Group 9 consists of late summer and early fall samples characterized by a ] fourbeard rockling larval assemblage. Besides modest numbers of rockling, a few other species were occasionally important in these samples (windowpane, witch flounder, hake, cunner), although both densities of larvae and numbers. of species were characteristically low. This was also a relatively small group in 1976-1984 (n=14) that received several additions in 1985-1987 (n=10). ] In general, the results of the 1987 discriminant analysis for fish larvae agreed with previous seasonal and species groupings determined by i numerical classification (NAI 1985b): 94% of the 1976-1984 sampics were classified by the discriminant functions into the'same groups as by the cluster analysis, and the classification of 1985-1987 samples followed a , 4 similar seasonal pattern to those from the earlier years. In most cases where the two methods differed, the samples in question had relatively low numbers of larvae. For example, Group 8 was originally a small group (only i seven samples in the nine-year period 1976-1984), but in the last three years. ' t an additional 13 samples have been classified here by the discriminant function analysis, including four from 1987. This tendency of discriminant functions to assign greater importance to minor groups compared to the , original numerical classification was also noted in the analysis of egg data. The two methods use different procedures to evaluate the similarity of individual samples with each other. Discriminant functions sometimes place r greater emphasis on subdominant species in differentiating among groups, whereas the Bray-Curtis similarity index used in the cluster analysis of the 1976-1984 data is strongly influenced by abundance, and thus places greater emphasis on the dominant species. Spatial Patterns of Fish Enns and Larvae Spatial comparison of abundance and species composition from the nearfield and farfield stations was previously done'using numerical classi-fication for both fish eggs and larvae. Spatial (station) differences were 119
found to be less important than short-term temporal differences (NAI 1983b, 1984b). Samples collected on the same date at different stations (nearfield or farfield) more likely resembled each other than if collected one to two weeks apart at the same station. This similarity in species compositic,n and abundance between nearfield and farfield sites was consistent with the known extent of water mass movements in the study area. During 1987, the relative abundance and frequency of occurrence of all taxa in Ichthyoplankton samples were very similar among the three areas sampled for both eggs and larvae (Tables 3.2.1-3 and 3.2.1-4). Tidal currents and longshore (northward and southward) currents in the study area are typically in the range of 0.2 to 0.6 knots about 75% of the time (NAI 1980d). Currents of this magnitude would transport a water mass about two nautical miles during a single tidal excursion, or about 5-15 miles in 24 hours during periods dominated by longshore flow. The distance from Nearfield Station P2 to PS (1-1/2 miles) or to P7 (3-1/2 miles) is relatively short. Considering that, for example, a water mass sampled at Station P2 could very possibly have been located at Station P7 a few hours before sampling, rigorous treatment of these locations as distinct from each other in terms of plankton is not justified. Since previous baseline reports have confirmed statistically that ichthyoplankton densities and species composition do not differ among stations, and data from 1987 are very similar among stations (Tables 3.2.1-3 and 3.2.1-4) no further analysis was con-ducted. Entrainment Species Assemblages Although Seabrook Station was not generating power or discharging heat in 1987, the circulating water system was operated for the entire year, however, pumps were only operating consistently enough to run the entrainment ; sampling apparatus from January through June. The flow rates for the sam-pling dates for the first six months are found on Table 3.2.1-5. Flow rates { per month averaged between 240 and 480 million gallons per day. As a pre-11minary evaluation of entrainment effects, ichthyoplankton samples were ; l 120
I i I l 1I l i TABLE 3.2.1-3. COMPARISON OF PERCENT ABUNDANCE AND PERCENT FREQUENCY OF 1 FISH EGG COLLECTIONS AT NEARFIELD (P2), FARFIELD (P7) AND { DISCHARGE (PS) STATIONS DURING 1987. SEABROOK BASELINE i REPORT, 1987. ) l 1 NEARFIELD FARFIELD DISCHARGE ! l j PERCENT PERCENT PERCENT PERCENT PERCENT PERCENT I ABUN- FRE- ABUN- FRE- ABUN- FRE-DANCE QUENCY DANCE QUENCY DANCE QUENCY j Brevoortia tyrannus 0.00 0.00 <0.01 2.17 <0.01 2.17 Enchelyopus cimbrius 2.34 60.87 3.03 56.52 3.40 52.17 Encholyopus/Urophycis 2.26 32.61 7.75 30.43 3.93 34.78 i Gadidae / Cryptocephalus 0.29 36.96 0.55 39.13 0.37 36.96 l Cadus vorhua 0.26 56.52 0.55 56.70 0.32 58.70 i Cadus/#elanogrammus 0.05 17.39 0.11 17.39 0.05 15.22 Glyptocephalus cynoglossus 0.15 28.26 0.43 36.96 0.31 32.61 , Hippoglossoides l platessoldes 0.16 30.43 0.37 34.78 0.29 39.13 Labridae/Limanda 65.36 50.00 52.84 54.35 35.34 52.17 Limanda ferruginea <0.01 2.17 0.06 4.35 <0.01 2.17
#elanogrammus negleffnus <0.01 4.35 <0.01 2.17 <0.01 2.17 #erlucclus bilinearls 0.34 23.91 1.31 26.09 0.60 28.26 Osteichthyes 0.00 0.00 0.02 2.17 0.00 0.00 Po11achius virens 0.02 19.57 0.04 21.74 0.05 23.91 Scomber scambrus 19.18 13.04 19.57 19.57 26.17 13.04 Scophthalmus aquosus 3.19 43.48 2.82 43.48 2.78 47.83
> Tautogs onitis 0.07 8.70 0.10 6.52 0.02 4.35 Tautogalabrus adspersus 3.96 32.61 7.26 28.26 3.16 34.78 Urcphycis sp. 2.35 45.65 3.20 43.48 3.21 47.83 r 121 s
TABLE 3.2.1-4. COMPARISON OF PERCENT ABUNDANCE AND PERCENT FREQUENCY OF LARVAL FISH SPECIES AT NEARFIELD (P2), FARFIELD (P7) AND DISCHARGE (PS) STATIONS DURING 1987. ONLY COMMON SPECIES ARE LISTED (PERCENT FREQUENCY AT LEAST 10% AT ONE OR MORE STATIONS). SEABROOK BASELINE REPORT, 1987. NEARFIEL.C FARFIELD DISCHARGE PERCENT PERCENT PERCENT PERCENT PERCENT PERCENT ABUN- FRE- ABUN- FRE- ABUN- FRE-DANCE QUENCY DANCE QUENCY DANCE QUENCY Ammodytes americanus 7.70 45.65 5.10 43.48 4.82 45.65 Anguilla rostrata 0.02 13.04 0.02 13.04 <0.01 2.17 Brevoortia tyrannus 1.50 8.70 1.05 10.87 2.23 13.04 Clupea harengus 3.70 54.35 7.17 50.00 4.25 52.17' Enchelyopus cimbrius 5.12 52.17 5.71 41.30 9.18 56.52 Cadus morhaa 0.14 39.13 0.06 36.96 0.14 45.65 Glyptocephalus cynoglossus 0.99 26.09 1.58 36.96 1.68 36.96 Hippoglossoides platessoldes 0.49 23.91 0.15 23.91 0.19 21.74 Limanda ferruginea 0.29 17.39 1.78 36.96 1.18 28.26 Liparis atlanticus 2.99 21.74 0.53 17.39 0.94 21.74 Liparis cohenf 0.39 28.26 0.24 30.43 0.38 36.96 Herlucclus bilinearls 2.10 21.74 1.44 19.57 3.62 21.74
- yoxocephalus aenaeus 0.33 23.91 0.44 26.09 0.18 21.74 Myoxocephalus octodecomspinosus 0.18 19.57 0.25 17.39 0.21 26.09 Hyoxocephalus scorplus 0.03 6.52 0.06 10.87 0.01 6.52 Pholls gunnellus 2.14 28.26 1.68 28.26 2.07 23.91 Pollachius virens 0.09 19.57 0.12 21.74 0.10 21.74 pseudopleuronectes americanus 1.89 23.91 1.65 17.39 1.31 23.91 \
Scomber scombrus 40.82 13.04 48.79 15.22 53.72 15.22 Scophthalmus aquosus 0.24 30.43 0.27 26.09 0.38 36.96 Sebastes sp. 0.20 13.04 0.12 13.04 0.16 15.22 , Tautoga onitis 0.40 21.74 0.09 10.87 0.03 13.04 Tautogolabrus adspersus 25.04 36.96 20.22 36.96 10.61 41.30 Ulvarla subbifurcata 2.38 41.30 0.98 43.48 1.96 41.30 I Urophycis sp. 0.48 21.74 0.35 21.74 0.33 28.26 l l l 122
/ ( TABLE 3.2.1-5. MEAN $10NTHLY FLO97 (MILLIONS OF GALLONS PER DAY) j THROUGH THE SEABROOK CIRCULATING WATER SYSTEM, JANUARY - JUNE 1987. SEABROOK BASELINE REPORT, 1987, 1 MEAN FLOW ) NUMBER OF DAYS (millions of MONTH OPERATING gallons / day) JAN 31 367 FEB 28 480 MARCH 31 432 APRIL 30 411 MAY 31 240 JUNE 30 266 123
collected periodically in the intake pumphouse (Station E1) from January 6 through June 10, 1987. Generally, entrainment samples were collected within hours of the offshore nearfield collections (Station P2), but not necessarily on the same day (Table 3.2.1-6). These two stations were chosen for compara-tive analysis because P2 is the closest offshore station to the intake structure (Figure 4.1-1). More samples were collected at the nearfield station (18 dates vs. 11), contributing to some differences discussed below. Since there were no samples collected at El for the month of March, data from Station P2 for March were not used in any comparisons between stations. Entrainment pump sample volumes averaged 100 m3 (ss designed) as compared to approximately 489 m for offshore towed net samples for the same time period (NAI 1987). Fish egg taxa in entrainment samples had similar species composi-tion to those in offshore nearfield collections (Table 3.2.1-7). Atlantic mackerel, American plaice, cod / witch flounder, fourbeard rockling/ hake, cunner / yellowtail flounder, and windowpane were the six most abundant taxa in the in-plant samples. In general, mean abundances and the total number of taxa at Station P2 exceeded those observed in entrainment samples. Species such as Atlantic mackerel, windowpane, and fourbeard rockling, which have large oil globules, exhibit characteristics similar to other buoyant species in the middle Atlantic bight (Kendall and Naplin 1981) in that they tend to be found more often at surface depths. Because of this tendency to concen-trate near the surface, eggs of these species were less abundant in the entrainment samples than in the oblique offshore tows, because the plant intake draws water from well below the surface. Cunner /yellowtail flounder eggs were two orders of magnitude higher in abundance at Station P2 than at Station E1. Although this species lacks, an oil globule, previous studies (NAI 1980, 1981) have shown that this species is present in much greater i abundances in middle and surface depths. Species such as American plaice and Atlantic cod / witch flounder, which lack oil, may be less buoyant and there-fore more abundant in the bottom portions of the water column, thus' account-Ing for the larger abundances observed in in-plant samples compared with { 1 ( 124 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 1
f: i TABLE 3.2.1-6. .ICHTHYOPLANKTON SAMPLING DATES AT ENTRAINMENT (EI) AND NEARFIELD (P2) SAMPLING STATIONS, JANUARY - JUNE 1987. SEABROOK BASELINE REPORT, 1987. SAMPLING DATES ) MONTH WEEK El P2 l ? Jan._ary 1 6 5 2 -- 12 3 -- 21 4 -- 28 i February 1 3 3 2 -- 12 3 17 18 4 -- 25 ! 1 / March -- 5 1 !j 2 -- 12 1 3 -- 19 ) i 4 -- 25 I April 1 2 8 2 16 -- 3 22 21 4 30 -- May 1 7 7 2 -- 14 3 -- 19 4 26 27 June 1 3 3 . 2 10 9 3 -- 18 4 -- 29
-- = Not sampled r
125 )
9 1 E 1 5 N 2 2 0 U P 2 J
- C E
6 D 6 9 2 9 l 1 6 1 E 1 Y L 1 t J 1 5 7 1 1 1 1 Z < 1 3 < < < G P 5 R F V O 2 N P l 0 5 7 0 0 0 E 3 m A l E S 2 0 2 1 1 9 8 8 6 1 N P 1 1 1 8 < O I 6 T T 8 C A 9 O T 1 S l 0 0 5 0 2 4 2 O 0 T E A M T N O M 6 0 2 4 3 3 0' 3 1 2 9 0 7 0 6 3 R P 4 5 2 E P P S E G S G 0 7 6 6 3 0 2 0 0 E l 2 5 4 E M S I F r 2 6 2 5 3 4 2 4 3 9 1 O 7. 2 6 7 3 1 3 5 2 8 P 8 7 2 4 1 i 9 , 1 1 G m U A 0 T 0 R l 8 8 0 0 0 2 2 2 0 0 0 0 O E 5 2 7 1 P /. ER O N E ( N I 1 0 7 3 1 2 0 E L 2 1 3 7 0 6 5 C E P 6 5 1 0 1 N S 7 4 A A OB D L U t K J B O 2 6 5 4 1 O 7 A O l 5 6 5 3 2 1 R E 5 4 1 1 N B 1 A A E E M S
. r 7 e - d 1 n u
2 o 3 l s f g r e r i e E l n l e c d L i i e d g e n B S a l r n n p u A E t k e u r i s ol T I w e c k o e t C o k d o c l d i d f E l a o r a f n h e P S l H e n c m u w i l e / d h o f i Y g n a p c r c ct l c i a
/ k i a i f i t t r i w c r t e t i t g n w e l o o e n b n H h n o e o n k d e l n a r a / c a t d l k n c n k l n l u l d t l u i l s u o i a o u t o t o i t a n e u C R W M P C A F A C M A T U Y C wJ&
P ill
.l1Ilj
~ N 7 0 5 6 7 3 3 1 9 1 0 A 2 3 3 4 6 4 1 2 E E P 9 7 4 4 P 3 5 N _ U _ J 2 1 4 9 9 4 1 4 0 1 1
- l 3 2 2 8 5 5 1 1 <
N E 2 1 1 - A J . 5 9 8 2 1 6 8 0 8 8 3 7 2 0 1 4 4 - 2 5 1 3 2, 9 2 _ P 1 1 9 8 _ 1 2 . E N U J 4 4 6 9 6 6 0 S 7 1 5 9 1 0 5 I l 1, 2 3 2 2 2 E 1 2 9 8 6 3 7 7 1 8 2 0 7 4 3 4 4 < P 1 5 1 7 Y A t f l 6 5 3 6 2 2 0 0 6 E 4 8 2 2 7 1 1 2 2 6 1 2 8 0 0 4 Z 2 < 1 P 1 L 7 I 8 R 9 P 6 0 5 5 2 1 5 1 A l 6 1 5 2 . E 1 h t n o m
't a
h
't n
2 3 7 2 e Y P 3 k R a. A t U e R r B E l 2 e F E 0 8 2 w s e
'l o p
Z m Y P 1
< 4 6 3 a R s A t U n N e A m J l o 7 7. 2 n E 2 i a .
r t - n
) e d r o e e n u d n n e i u s t o u n l a o f c C r g e
( l e l n b e d i i r e n a l d S e c u t k A e 7 E k i o e w c X d
- I C
c a al l k a o o d A u 1 f l r k o T l 2 E P p p h
/ e n l e c o
c c S c n h c g a r d d c F x - 3 a n /y . h O e i t p a d i k s o w eb a h_ t c i i r t c i R h E n i w l e h n o f E .c L a r / k n d r / a l p r B B l e d c n n u d l l m a. " A T t m o o u i o o t o uL f U t A A C R C. M F C A P N a I [ I llll ll
\
offshore samples. Larger sample volumes and greater frequency of collection contributed to the higher number of taxa found in the offshore samples ( compared to entrainment samples, z
?
f Entrained fish larvae also followed trends in species composition similar to those observed in the offshore nearfield station collections
,]
(Table 3.2.1-8). Abundance of larvae at both stations was virtually identi-cal for all species, except American sand lance, which was four times higher j at the offshore nearfield station than at the entrainment station. American' d sand lance larvae have been shown to prefer surface depths (Dalley and Winters 1987), which might explain the larger abundances for the offshore ' oblique tows at Station P2 (the cooling water-intake Js 5 m above the. bottom in 17 m of water). 'As was the case for fish eggs, offshore collections, which had larger sample volumes and greater sampling frequency,' exhibited a higher number of taxa than found at the nearfield station. I I' t 3.2.1.2 Selected Species Larvae of nine fish species were selected for a detailed analysis-of their within year and among-year patterns of abundance because of their l numerical dominance or importance as a recreational or commercial species. l Analyses were based on a series of monthly means for Nearfield Station P2 samples collected from July 1975 through December 1987. These monthly means I were averages of two to four tows on one to four dates within each month. l l l Each of the nine species displayed distinct seasonal patterns of f abundance. While fish larvae were present in every month, the larvae of'each species exhibited a sharply defined period of only a few months' duration in-which their peak abundance' occurred. Values in other months were typically l much lower and were often zero. Theseseasot$alfluctuationsweretheprimary l' reason for the high within-year variances calculated"for each species (NAI 1983b). To reduce overall variability and improve' statistical power, or-ability to detect significant year-to-year differences in abundance, seasonal 128 1
ll
,.j l
~
- N A 2 E P M 6 9 1 3 6 4 3 1 1 1 1 1 0 2 2 1 1 1 1 1 1
. C 7 E 8
9 D - 1 L l 8 3 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 c U E 2 2 J T R O ~ P E R 2 3 3 3 1 1 5 P 5 < < E N C F U E D S l 4 9 2 0 0 3 A E 8 B K ) 0 t i d B 2 5 7 1 > 0 1 3 1 6 e A P 9 1 < < < u E 6 n S V i O t N n o 2 P l E 3 4 7 0 2 2 0 0 4 ( c 2 D N A l 2 9 2 1 1 1 1 2 1 8 E P 2 1 < < S 4 6 N 8 T O 9 C I 1 O T A 9 0 1 1 O 0 0 0 3 T l 3 S E 0 1 T A . H T. 1 2 1 2 1 1 1 1 8 N 2 < < < < < O P H. P R E E S P l 0 1 1 2 1 0 0 0 4 E A E < < < V R A. ' 1 H 2 8 2 4 1 1 0 8 5 1 1 9 S P 1 < < < < I F G U F A O l
)
E 4 3 2 0 O 1 0 0 0 0 4 m 0 0 0 1 2 6 9 2
/. P 1 1
1 3 1 2 2 7 O N L I U J E C N l 0 0 0 0 0 0 0 0 A E M U B A w N - A m E I s
. g e e r -
c i e 8 g n h n c l d. 1 n i l y i s a ep e g - l r ra u i k- n f s e r i o A 2 r x* n e d k e t y l X S r a p n d c d d i n f A 3 E e r h i a e a n o h n T I h s p s i m uo en c w a l C d f h h i F E E c r d n n i s l c l a c c s a O B P i k a et r ea c t e i i i f p i i t . A S t c r e n a f a t w t t c w R _ T n o e b a h i e d e n a h o n n i o E a l n r i t r d i s s a ct d a al t e l l l n u d r e i d o a l n l c k l B t A P o C u o R a o m n a o eS t i i t t r a e t U F N A U B G A MM A A A M Y N or c,. [e l llllI
N 2 3 5 5 3 2 7 1 8 0 0 A 2 7 2 4 1 E P 1 , M ~ N U J ._ N l 9 6 2 0 o 8 6 3 3 1 1 A E J 4 3 1 1 t < _ . 4 6 5 2 3 5 a Z 1 7 4 _ P E U J l 6 0 4 8 5 4 E 5 4 3 1 1 2 6 6 6 1 1 3 2 1 3 9 P 2 1 < 4 1 <
. 3 1 Y
A M l 5 0 2 0 5 0 0 0 0 3 E 5 7 _ 8 9 1 2 2 2 0 2 1 4 4 1 1 9 . _ P 2 4 2 < < 1 h L t I n R o P m A l 6 9 4 7 0 1 1 1 2 8 t E 3 2 5 3 a h - t n. e 3 1 0 6 2 4 0 0 6 k Y 2 5 2 1 a _ R P 1 t A U e R r B . e E l F E 0 4 1 3 5 1 5 0 4 5 2 7 w s
~
e l p 2 0 m 1 1 4 1 0 6 a Y P R 0 4 2 < 1 s - A t U n N e A m J l E 0 0 0 3 0 7 3 n 1 2 i _ a _ r t n
) e d o e n u
n e i t s n u o a C c e c e ( n n b a g i S l r ec e n p d i h l
- A e 8 E d d i r s u X d
- I C
n n al r e o d i c A u 1 a l u f s T l E s e ol p h c l c 2 P n i e F x 3 S l i a - n n u f n a i i c c a n h c n O e a c y g r c t t s a i R h n i b e i n n t p c E s r b k t r al a f s l r B a e u c n e l u u a A T S e m A G r o i m R M A t A t A l u o c G M S N P B a M. Hw Ii.l? I i lli !
i mean abundances (and upper and lower confidence limits) were calculated using data only from sampling periods which encompassed the seasonal peak in larval abundance. These select periods included the season of maximum yearly abundance and approximately 90% of total yearly catch for each species. Abundances from this subset were used to test for significant differences ( among years with a one-way analysis of variance and when differences were found to be significant they were subjected to a Waller-Duncan K-ratio t-test for multiple comparisons. Because 1975 data only include July-December samples, that year was only included in the analysis of variance for those taxa whose peak season does not include months prior to July: hake, Atlantic herrirg, and pollock. The analysis of pollock data excludes 1987 because each year's peak season for pollock includes January and February of the following year, and 1988 data are not included in this baseline report. Merical Sand Lance f American sand lance larvae continued to exhibit a December through July presence with peak abundance occurring from January through April L (Figure 3.2.1-1). In 1987, abundances dropped off in April but continued through June, then dropped to zero in July. This broad peak was due pri-marily to two factors: an extended hatching period and a long planktonic l stage for larvae (Bigelow and Schroeder 1953). Sand lance, the most abundant species over all years, has been highly variable (Table 3.2.1-9). Starting i i in 1976, with 353 larvae per 1000 cubic meters, abundancas decreased in 1977 to 35 larvae per 1000 cubic meters, the lowest value for any year of the study. In 1978, the abundances of sand lance increased to 384 le.rvae per 1000 cubic meters, then in subsequent years alternately decreased then increased. The highest abundance for sand lance larvae was recorded in 1982 (448 larvae /1000 m ). Abundance for 1987 (87.9 larvae /1000 m ) was'the third lowest abundance during the thirteen years of the study. Using the peak season data, a one-way analysis of variance showed no significant difference among years for log (x + 1) transformed abundances (Table 3.2.1-10). , 131 l l l l
American sand lance 4-m .. w
- o. m 3- ,,
gm " a,h
, ' . . .....s
.. ; N OVERALL MEAN
... .. mr D s zo 2- .
pE '.,
+D .* *
!$. U ,, .,
no ~
.~
3h 'd,
..'..r O , , , , , ,
.x, JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NO/ DEC MONTH 3
winter flounder m w
- 0. m e, g@ 2-
/X g[n co ovERAU.MEAN 1987 za C5
+D 1- ;
ag ..: Oo : . ae : g.....! 0 , , , , , , , ,w, , , , JAN FEB MAR APR MAY JUN JUl. AUG SEP OCT NO/ CEC MONTH Figure 3.2.1-1. Mean and 95% confidence limits over all years and 1987 values, by gonth, for log (x+1) transformed abundance (No./1000 m ) for American sand lance and winter ; flounder larvae at stations P2 and P3, July 1975 through December 1987. Seabrook Baseline Report, 1987. . 132
O H 9 9 2 1 5 9 2 9 4 _ C 0 9 2 1 L S E L I L C A 9 E - N 0 8 6 5 0 4 4 0 P R A 8 4 7 S E E 7 3 3 2 9 0 V M 4 1 4 3 H O 1 S I . F 7 . 8 7 9 4 7 6 5 2 2 8 D9 8 9 7 5 1 0 8 5 3 8 T 1 5 2 I 1 8 1 ' C , 2 IT 1 R E O 6 8 1 3 6 4 4 1 7 2 S P 8 2 6 E 9 4 9 5 1 2 0 1 F R 1 1 2 ~ O 1 1 3 1 1 E R N - A I 5 5 4 2 3 7 7 0 5 8 E L 8 YE 9 1 2 2 1 1 0 0 1 2 3 S 1 7 2 1 4 1 1 Y A - B B I K 4 8 7 8 1 4 7 8 3 8 O 8 MO 3 9 2 2 8 2 7 0 2 9 R 1 7 1 2 4 2 0 B 0 A 0 E 1 S 3 0 4 3 8 0 9 4 3 4 8 R 9 5 4 4 1 2 7 0 9 3 E 1 9 1 1 9 1 P 7. 8 R 9 E 1 2 7 4 3 8 3 6 4 7 1 B 8 R R 9 7 2 0 2 4 2 2 2 2 E 1 4 1 2 6 MB E 4 D R E C A 1 7 9 3 9 4 1 9 0 0 C E E 8 l l D Y 9 3 2 1 9 2 9 5 0 6 A 1 1 1 2 5 eHG t 2 U U B O 0 7 5 5 4 2 7 4 0 3 A R 8 H 9 9 9 6 3 4 7 5 4 7 K T 1 1 2 9 3 A 2 E 5 P 7 9 9 2 9 4 2 0 2 2 4 2 F 1 7 O 9 3 7 2 1 8 6 8 7 9 Y 1 0 1 4 4 N L 2 O U S J A 8 0 6 1 1 3 3 7 1 9 E 2 7 S P 9 4 7 4 6 2 0 2 2 1 1 8 1 1 3 F N 3 OO I N T 7 0 4 2 4 4 5 2* 1 1 A A 7 E T 9 5 0 0 9 5 4 4. 6 5 M S 1 3 1 2 2 1 2 C T I A R 9 5 7 7 6 1 5 7 7 T E 6 E A 7 2 2 3 4 2 1 0 4 7 V 9 5 1 2 4 2 GR E A 1 3 1 G L 5 5 0 2
. 7 a 9 9 - - - - - - 6 7 2 - 1 9 1 1 1 2
3 e r c e E n d l L ) a n e g B d l r u r n A e e o e i T d d d d l k r n u n n f d c I r a l ai u I i o1 a ) p i et t I c s rp ol l g cl m g e p h c b n l u i u - u u S e e e S i n A f J aA cJ cA - S cD F E a - - t - i - i - e - i - k - I s c n r r w y t r t y r n l t t c v C E h t i a e p o a n p n a e u u n c o o r J t A l M a A a M n J eJ a O l N P n et n i l l I l n I k t l ( l ( S o m i e i t t i u a t o m A H Y A A C H A P Hww j
F . 7 9 6 O7 8 7 8 8
) 9 1
m, 9 7 3 8 8 7 0T 0R 0O 1 P 5 7 2 E 8 7 8
/. R O
NE N 6 5 3 E I 8 8 8 SL EE CS 3 A 0 3 7 1 AB 8 8 8 O K 3 O t S BO N 4 0 7 AR O 8 8 7 B S DA _ I EE R MS A 2 4 0 R P 8 8 8 O f F . 57 a C M8 A9 E 0 1 5 R1 L 8 8 7 T P
)
R I E T 1E L U 6 2 5
+D
_ M 7 8 8 _ C (xE D GH 7 6 4 _ OG 7 8 8 LU O FR OH _ T 1 6 6 - S 8 7 7 R5 _ A7 E9 _ Y1 _ 8 5 9 GY 7 7 7 _ NL OU MJ A , S S NT AN H F [ 5 4 4 7
"5 3
N 8 3 6 4 1 2 5 9 5 3 IO Z. RM 1 0 1 2 0 1 1 1 3 _ A VD E FT OC 359 1 67 235 392 932 900 31 4 763 61 7 S 459 820 066 449 71 9 SE IE S 1 78 731 684 089 729 427 066 077 583 1 91 034 796 943 SS 1 89 1 1 1 67 1 45 67 258 1 67 1 67 1 57 Y 1 1 1 1 1 1 LG AN NI AR U f 1 78 1 89 1 01 1 89 I 01 1 78 279 224 1 1 1 YD d 1 01 11 2 1 23 1 1 2 I 23 1 1 2 1 89 1 89 101 A 1 1 1 1 11 1 1 1 1 1 1 1 1 MS E EI MC C E FN _ P OO FS I srl srl srl srl srl srl srl srl srl O D ET CA roa art roa art roa art roa roa roa roa art roa roa SE RI UR ero ero ero eroart art ero art ero ero ero art art ero _ TT LC YET YET YET YET YET YET YET YET YET _ OA U SV SE _ EE RS _ e r c e n d l _ 0 I a n e g 1 D l r u r n _ 1 OE
) D d d e
l o k e i r _ AU n n f d cI r _ 2 E L ai ul i ol ag ) I e! ) _ C sr ol l g cl mu p p h e b 3 SN u p l u i u A e e e e EI I nA a-fJ aA t - cJ c- S S cD F
- i - i y i - k -
E CS cn rr wy t r t a rn l tt cv _ B EH i a ep oa np nM eu u nc oo A PT rJ tA lM aA ai nJ eJ ao lN T SN et n( li l( l nI kI lt l( O m i e t t u a t o M A M Y A A C H A P w W r-
!l
l ! Winter Flounder l^ l Winter flounder larvae, the fourth most abundant over all years of , the nine selected species, are usually present from March through September, I with the highest concentrations occurring in April through July (Figure j 3.2.1-1). Very few specimens were encountered in March, August and September. In 1987, abundances followed the same general pattern as in l l previous years. Winter flounder larvae, highly variable in earlier years, l decreased to an all time low in 1981 (2.9 1arvae/1000 m ) then increased during the next four years to the highest abundance (22.4 larvae /1000 m ) recorded during the study. Since that time, the abundance has decreased in both 1986 and 1987 (Tabic 3.2.1-9). A one-way analysis of variance of the peak month data showed no significant difference among years (Table 3.2.1-10). Yellowtail Flounder Yellowtail flounder larvae normally occur from May through November, with peak abundances occurring from May through August. In recent years there have been an increasing number of larvae present in April, with 1987 recording the highest abundance for that month (Figure 3.2.1-2). In 1987, abundances dropped to zero in May but then increased to normal values in June and followed the general pattern of abundance through November. Yellowtail flounder, like most of the selected species, has been highly variable from year to year (Table 3.2.1-9). Starting with the highest value in 1977 (20.2 larvae /1000 m ) abundances generally decreased to the lowest 3 value in 1982 (0.3 larvae /1000 m ) and then varied from year to year through 3 1987. Abundance in 1987 (1.7 1arvae/1000 m ) was the third lowest abundance observed and was half the overall yearly geometric mean of 3.6 larvae per 1000 cubic meters. The one-way analysis of variance to test overall yearly differences in log-transformed means was not significant. 13!,
- y;il;,wtail ft:undir
, 2.0 -
t E I w- .
}
- o. m 1.5- .
h =W '. t Ex 1.0 - l '. zo -
...~.. 'oVEfMU.MEAN 1987
_g' , f- e, TD . t :.
- 15. o ,! '
o8 05' l '. Oo aw :
..- .j
.... y.._ _
0.0 . , , , , , , . . . . JAN FEB MAR APR MAY JUN JUL AUG SEP - OCT C DEC I
' MONTH i
1 2.0- Atlantic cod jf E W - Q. m OVERALL MEAN 1.5 g E W
. . . - . . 1987 w
zo 1.0 - . j g . .. q
+D ;
xo 1 1 eo 0.5 - / ;, ,* * * * * . . . . . . . , , , j Oo
. t
\./'.
. . . . . . N** . .
Cw. . j l i 0.0 JAN FEB MAR' APR MAY JUN JUL AUG SEP OCT NO/ DEC l 1 MONTH I Figure 3.2.1-2. Mean and 95% confidence limits over all years end 1987 values, by genth, for log (x+1) transformed abundances (No./1000 m ) for yellowtail flounder and Atlantic , cod larvae stations P2 and P3, July 1975 through December 1987. Seabrook Baseline. Report, 1987. ; 136- t i
i l i' l 1 Atlantic Cod l Atlantic cod larvae occurred sporadically from 1976 through 1987 j 1 L exhibiting a bimodal distribution with one peak lasting from November through January (late fall-winter) and the other (usually stronger) peak in April f through July (spring-early summer, Figure 3.2.1-2). Cod larvae also i exhibited a bimodal distribution in 1987, however the April through July peak ) , l wcs not as strong as usual. In addition, this peak extended through August 1 > f instead of decreasing as in previous years. Seasonal geometric mean abund- ) i ance for Atlantic cod was only computed for the spring-early summer peak, due i to the usually higher abundances and the longer period of occurrence in comparison to the late fall-winter peak. In 1987, spring Atlantic cod larvae attained their lowest abundance (0.6 larvae /1000 m ) in the twelve years of , the study, thus continuing to exhibit below-average abundance levels and a l general declining trend which began in 1982 (Table 3.2.1-9). A one-way analysis of variance among years found the differences to be significant l l (Table 3.2.1-10). The Duncan-Waller multiple comparison test shows that 1978 abundances were significantly higher than in 1979 and 1983 through 1987, and q 1977 and 1981 abundances were significantly higher than those in 1987. I l Atlantic Mackerel Atlantic mackerel larvae exhibited a May through August pattern of I occurrence for all years combined, with peak abundances occurring in July and no larvae found in October through April (Figure 3.2,1-3). In 1987, mackerel larvan were only found in June and July, with June having a much larger value , than the overall mean. Seasonal mean abundances for mackerel larvae were variable throughout the study period but have generally been increasing since 1978 (2.3 1arvae/1000 m ). The highest value occurred in 1980 (24.2 larvae / 1000 m ) with the average over all years being 9.0 larvae per 1000 cubic meters. In 1987, the abundance was slightly lower than the overall mean (Table 3.2.1-9). A one-way analysis of variance found no significant dif-ference among log-transformed yearly means. 137
I 4 1 i Atlantic mackerel i 4- 1 I r 1 I. a: : w 3- :
*. . . I am ! *
, j g O' !.
W L 4 w$ a2 : i OVERALL MEAN g=
=s pm 2-l / i,
... .. .7 .
+3 : i EU :
eo
- . I c8 1- .:'
J ,- ,
. I
* \
0 . , , , f - "i , , N' , , , 1 JAN FEB MAR APR MAY JUN JUL AUG SEP CCT PO/ EC j MONTH 4- cunner a:
- w 3- - ~~~~".**
iim[ OVERAU.MEAN ,
/N '
\.*
3 : s2
... .. 1987 . .
. s i zo 2- /
- pij5
. -. + o . :
/. .
i 6U l '. 08 ! '. oo Jr 3 i l :
- 5.
0 , , , ., , , , , , , , 1 I. JAN FEB MAR APR MAY JUN JUL AUG SEP OCT tO/ DEC 1 i MONTH l l Figure 3.2 1-3. Mean and 95% confidence limits over all years.and 1987
- j. values, by genth, for log (x+1) transformed abundances (No./1000 m ) for Atlantic mackerel and cunner larvae at stations P2 and P3, July 1975 through December 1987.
Seabrook Baseline Report, 1987. 138
y i l t j Cunner 1 j -! Cunner larvae were present throughout June through September, - following a pattern of occurrence similar to mackerel larvae. Cunner larvae peaked historically during July and' August and usually disappeared by,0ctober' - (Figure'3.2.1-3). In 1987, values for June through October were all greater ' l than the.overall means for those months. Seasonal mean abundances for cunner ! i
- -larvae'have been highly variable throughout the past twelve years.(Table. ..l 3.2.1-9), with 1987 exhibiting the highest abundance (255.2 2arvae/1000 m )3 .
during this period. Cunner larvae were also the most abundant of the nine l . selected species in 1987-. The.one-way analysis of variance testing ~ j difference between'the log-transformed yearly means showed no significant. ! I difference among the years.
-1 Hakes Hake larvae, like mackerel and cunner, are confined to a relatively ,
short period of occurrence. Ifistorically, they have increased through June and July peaking in August and September, decreasing in October, and almost ; disappearing in November (Figure 3.2.1-4). In 1987, larvae were not caught until August, with the peak abundance not coming until September, and with ; values for October and November higher than the overall means for those months. Seasonal mean abundance was highly variable among years, with the general trend suggesting relatively high abundances followed by two or three years of relatively low abundances (Table 3.2.3-9). The abundance in 1986 (0.1 larvae /1000 m ) was the lowest value in the past twelve years. The 1987 3 abundance was higher (3.2 larvae /1000 m ), but was still below the overall mean of 4.4 larvae per 1000 cubic meters. A one way. analysis of variance 'I
~
showed no significant difference among yearly means. P l' 139
hake 2.0 - 5 1.5 - nm / *, m m '
/ i OVERALL MEAN .,
m= .
. . . . . m7 , .
zo 1.0 - . j ', PE
+3
\*
Eo j- ' 8j a-0.5 - [ .\
~
./: ' ...
s 0.0 .
/ . . .
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT to/ DEC MONTH Atlantic herring 3-M l' . W . Amg ! . g W g ,,, OVERALL MEAN 1987 g/
- w&
m : E2 / zo . pE
+3 6U j. ' . , , * . .,
,I -
\ .
..., l' 0
.N.'. .
l JAN FEB MAR APR MAY JUN JUL AUG SEP OCT PO/ TC MONTH Figure 3.2.1-4. Mean and 95% confidence limits over all years and 1987 values, by gonth, for log (x+1) transformed abundances (No./1000 m ) for hake and Atlantic herring larvae at stations P2 and P3, July 1975 through December 1987. Seabrook Baseline Report, 1987. 140 !
'l
.i Atlantic Herring
- 'l Atlantic herring larvae typically' occurred throughout most of.the 1 year, except during June through September when abundances.were either at or )
near zero (Figure 3.2.1-4). January through May saw medium to low j L abundances, and October through December exhibited the peak values. In l'987, l r . i herring followed a pattern similar to that in previous years except that ! January through May and November abundances were higher and October was lower ~ th'an their overall monthly'means. As is the case with most of the other ! selected species, herring larvae have a highly variable seasonal mean abundance (Table 3.2.1-9). The highest abundances occurred in 1975 and 1976 . (197 and 145 larvae /1000 3m respectively), the lowest in 1978 (2.1 ) 3 i larvae /1000 m ), averaging 30.9 larvae'per 1000 cubic meters over all years. ! The 1987 abundances (28.8 1arvae/1000 3m ) were only slightly below the overall mean. A one-way analysis of variance testing the differences among i years found them to be significant (Table 3.2.1-10). The Waller-Duncan multiple comparison test showed three large overlapping groups of years,-with 1 1978 abundances being significantly lower than those in 1975, 1976,..and 1986, and 1979 abundances being significantly lower than those in 1975. j Pollock Pollock larvae exhibited an abundance pattern similar to that.of ; herring larvae, with large abundances in November through February and I decreasing abundances from March through June (Figure 3.2.1-5). During July i through October few if any larvae were present. The abundance of pollock larvac in 1987 was very low during most months, with only November and May slightly above their overall means. Seasonal peak abundances for pollock were highly variable from year to year (Table 3.2.1-9), with increasing abundances followed by two or three years of decreasing abundances. In 1987, the seasonal mean was not computed for pollock because its period of peak j abundance which began in November would continue into 1988. However, the 1986 data which were not included in last year's baseline report were the 141
1 1 i 1 pollock 2.0 - 1.5- + E
- a. m .
ce cc wW .. == to $ gn - i 1.0 - za < {! U
~
OVERALL MEAN *., M,,,,, . . . . . 1967 *
., j 88 0.5- -
l 0.0 _,... **** ...,, \ ,
.)
l JdN FdB MAR APR MAY JUN JbL AbG SbP . OCT. tb/ Dhc MONTH - l Figure 3.2.1-5. Mean and 95% confidence limits over all years and 1987 ]
. values, by genth, for log (x+1) transformed abundances l- (No./1000 m ) for pollock larvae at stations P2 and P3, July 1975 through December 1987. Seabrook Baseline Report, 1987.
.lE 1
.142
) I ! Iowest encountered during the 1975 through 1986 baseline period (1.2 larvae / / 3 1000 m ). This severe drop in abundance follows the relatively high abundance in 1984 of 22.8 larvae per 1000 cubic meters. The one-way analysis of variance among yearly log-transformed means showed the differences to be i J very highly significant (Table 3.2.1-10). The Waller-Duncan multiple com- ] ) > parison test of the yearly means showed three overlapping groups of years. Abundances in 1976, 1979, and 1984 were significantly higher than in 1978, 1982, and 1986; and abundances in 1979 were also significantly higher than in ) 1977, 1981, and 1983. 3.2.2 Adult Finfish f 1 i 3.2.2.1 Total Community Temporal Patterns in the Demersal Fish Community l Otter trawl catch per unit of effort (CPUE) for all stations and species combined during the 1976 through 1987 period rose from 50 fish / ten- I minute tow (fish / tow) in 1977 to a peak of 95 fish / tow in 1980 and 1981 1 (Figure 3.2.2-1). CPUE subsequently declined through 1985 when an average of l 43 fish / tow were collected. The CPUE increased to 52 fish / tow in 1987, possibly indicating an increase in the low abundances recorded since 1981. Changes in the annual composition of the demersal fish community were compared using percent composition of the dominant trawl species. Six taxa accounted for nearly 80 percent of the trawl catch abundance for all years combined (Table 3.2.2-1). Yellowtail flounder comprised the largest percentage of the annus1 catch (20-36%) in all years except 1983 and 1984, when it ranked second below longhorn sculpin. Beginning in 1980, the per-centage of yellowtail flounder in trawl collections consistently declined until 1934 when that species represented only 18 percent of the total annual catch. Percent contribution of yellowtail flounder increased to 27 percent in 1985 ending a five-year declini , but dropped again in 1986 (20%) and 1987 (19%) to a level approaching the 1984 low. Hake species (red, white and l 143
. 7 D
?*.*.*
8 E _ N .
. .*. f
- N E
., .. 6 M
O 8 C - . l S s . l 2 3 N ., 1 T T T O s , I 5 N N N T A v .*.% , , . 8 O O I I OI T % T T T A A A S. i ., 4 ..s ) T T T l .,. S S S A ~ s
..'.\
s
- 4 8
. . N '
- .- g
- N N 3
.~
s s g 8
.' N
- s' s
- 2 s g%s t .
.'.'g s.'. 8 R
g Yg i's., A E
\
i.s - Y
\
n,s 1 8 p ", ' 0 ['e *;;.f 8
) /
.*;./
- 9 7
./#./ I r p
/
../ j# #
J 'e*
. 7 8
/* - .,
f- ., w N /*.'j s . 7
..v 7 r '
~ .
N ,
.~
s ' r . 6 7 0 0 0 0 0 2 3 6 4 2 1
>EOLEm -
tZ:s EW" oF(*O Hvo
_ SD RE _ AI ) ED 7 5 4 9 7 7 5 3 3 2 3 2 3 3 S L YB 2 1 1 4 ( W A LG LC R A _ T R E ) T - T 7 9 0 9 1 6 5 1 1 3 1 8 1 5 5 O 8 1 1 1 1 1 < < 2 9 1 N 1 I - S7 ) E8 2 7 7 I9 6 0 4 9 0 3 3 4 8 3 1 1 C1 8 2 1 1 1 < 2 - E _ P 1 9 ( . S . TR T
)
NO 7 5 2 9 3 3 5 3 0 AP 5 1 1 1 1 1 8 2 1 2 1 < < < 2 lWE R 9 ( U 1 - BE AN TL I 7 5 7 2
)
6 SE 4 8 3 7 7 5 8 1 1 1 OS 8 1 1 2 < < < 2 MA 9 1 B 1 E VK N LO O ) EO I HR T 3 9 0 4 8 8 9 7 1 3 2 5 1 3 6 TB I 8 1 1 2 2 A S 9 ( EE O 1 HS P T f N R . I C ) OD T 2 2 9 6 9 7 5 3 4 2 1 2 2 8 8 FE
- N 8
9 2 1 1 2 ( DI E 1 EB Nr C R - Ia E ) EC P 1 8 4 7 5 6 6 2 3 2 2 2 1 3 7 G3 CT 8 9 2 1 1 1 < 2 ( _ 1 SO RD AA - E ) Y2 L L , T 0 8 9 1 3 3 8 5 1 2 1 9 4 2 1 1 7 3 4 1 2 2 ( A1 T O D S ) AN 9 4 9 3 7 4 7 2 3 2 4 1 3 2 5 . O 7 3 1 1 < 2 RI 9 ( AT 1 EA YT S Y ) _ BT 8 3 9 9 9 4 0 2 4 3 1 1 1 5 6 A 7 2 1 1 1 < < 2 N 9 ( O7 1 I8 T9 I1 S ) - OH 7 9 0 8 8 3 3 5 3 4 1 2 2 3 2 PG 7 2 3 < 2 MU 9 ( s OO CR 1 se et H ka TT ak N i hs E6 6 6 8 5 5 4 3 3 6 2 1 2 3 3 5 C7 7 3 1 1 < 2 dy R9 9 ( en E1 1 tr P to G oh LN pt - AI TR s d UU s dn TD e na i c a, _
. r e ,e 1 e p el 2 - d n n g s tt it u i r n r hi 2 o p e i e wl l
- l d t s t s h -
3 f s u n d l e i e t ,, e c u o e i h i o dg E l i s o c m c w t e c ei L i c l c s ep u n e f rb B A t a ep n r f i w s i c ep k a p l e p s o ss . T w s o r t o t c w c r ce . o h g e n b e n n o o o r e ad l e t a n t a a l d d e b uu l k n n l i a l e l n d h m ll Y e a o i M L M t A R a k S t A O c o i a P M M t O N u cc nn ii
*b g&u -
I t i spotted hake) were the second-ranked taxon in traw1 collections and comprised 2
~
15% of the catch for all years combined. The percent composit1on of hake. species was variable over the years (8-30%) and showed no consistent long-term trends. Longhorn sculpin comprised 14% of the catch for all years ; combined, and accounted for an increasingly larger percent of the catch from 1976 (5%) through 1984 (27%). In 1986 and 1987, their percent contribution l { ' to the total catch fell back to pre-1979 levels (<10%). Winter flounder ranked fourth in percent abundance over all years (9%) and ranged from 5 to j 15% of the total annual catch. The percentage of winter flounder in otter k trawl collections gradually increased from 7% in 1984 to 11% in 1987. Atlantic cod ranked fifth over all years, and accounted for an average of seven percent of the total catch. Cod percent contribution was highest in 1978 and 1979 (14% each year), and lowest in 1977, 1985 and'1986 (3% each -j year). The percent contribution increased to 6% in 1987, but was still below the 12-year average (7%). . Rainbow smelt, the sixth ranked taxon, fluctuated between 15% (1987) and 1% (1985) of the total annual catch, averaging 6% over i all years. Percent composition in 1987 was the highest during the study l period, with 1976 (13%) ranking second. The number of fish species (species richness) collected annually in l otter trawls ranged from 32 to 40 and totaled 55 for all years combined (Table 3.2.2-1). .j Seasonal changes in the demersal community were examined in past l years by numerical classification of the trawl catches (NAI 1982c). Samples were classified into two mejor groups, reflecting a " winter community" (December through March) and a " summer community" (April through November). Rainbow smelt was the only specit.s that was consistently more abundant in the winter throughout the study area. Catches of' hakes and longhorn sculpins were substantially greater in the summer. I 146
) I L 'l S 2 ntial Patterns in the Demersal Fish Community-Mean annual catch per unit of effort was similar at the offshore' 1 stations (T1 and T3), while CPUE at the shallower nearshore station (T2) was j ( much lower (Figure 3.2.2-1). Derpite the differences, mean annual CPUE for l
.1 the three stations followed the same long-term abundance pattern from 1976 through 1987. As discussed previously, CPUE for all stations was low in l 1977, peaked in 1980 and 1981, declined to lowest levels in 1985, and began I to gradually increase in 1986 and 1987.
i i 1 Otter trawl catches'at the offshore stations (T1 and T3) were i dominated by yellowtail flounder, hakes, and' longhorn sculpin (Table
- j. 3.2.2-2). Collectively, these species comprised over 60% of the catch for I J
all years combined at Stations T1 and T3. Of lesser.importance at these stations were Atlantic cod, Atlantic whiting and skates. The most notable difference in percent composition between Stations T1 and T3 was that yellow-tail flounder predominated at Station T1 while longhorn sculpin was more j abundant at Station T3. In addition, cod, skates, and ocean pout comprised a larger percentage of the total catch at Station T3. This and other. smaller differences in species composition between Stations T1 and T3 may be attribu- j 1 table to different bottom substrates. Station T1 has a sandy bottom, while the bottom substrate at Station T3 is sand, littered with small cobble and shell debris (NAI 1988). Yellowtail flounder prefer any sandy bottom (Bigelow and Schroeder 1953). Otter trawl catches at the nearshore station (T2) were dominated by winter flounder, yellowtail flounder, rainbow smelt, . and pollock, comprising 67% of the catch for all years combined. ' Hake and .j l sculpin comprised a much smaller percentage at Station T2 than at Stations T1 .l 1 and T3 while the opposite was true of winter flounder, rainbow smelt and i l pollock. I l 1 Temporal Patterns in the PelaRic Fish Community , I 1 Catch per unit of effort for gill nets (one 24-hour set) combined J for all species showed a pattern somewhat similar to otter trawl catches l I 147
'l l
TABLE 3.2.2-2. TOTAL PERCENT COMPOSITION BY STATION OF ABUNDANT SPECIES ' COLLECTED IN OTTER TRAWLS, ALL YEARS COMBINED (1976-1987). SEABROOK BASELINE REPORT, 1987. i PERCENT COMPOSITION - SPECIES T1 T2 T3 j ( Yellowtail flounder 39 14 21 IIake species a 16 10 16 Longhorn sculpin 12 5 22 ; 5 Atlantic cod 5 5 10 l Rainbow smelt 5 17 3 l Winter flounder 6 26 5 Atlantic whiting 4 1 3 Windowpane 4 4 2 Skate species b 3 2 8 l Pollock 2 7 1 l Ocean pout 1 3 4 ! I fladdock 1 <1 3 J Other species 2 5 2 I Number of other species (42) (33) (38) a I includes red, white, and spotted hakes l includes big, little, and thorny skates ! l l
)
i 148 l j _ _ - - - _ - - - - - - - - - - - - - - - -- - )
l l 1 (Figure 3.2.2-2). CPUE rose to a peak in 1980 of 29 fish / net and subse-quently declined to lowest levels'in 1985 of 3 fish / net. In 1987 CPUE remained low and was virtually identical to levels encountered in 1984. Sampling frequency for gill nets has been less in recent years, and this change may have impacted the catch statistics. The pattern was not as I distinctive as with trawls, in that annual CPUE only ranged from 3 to 16 with ) the exception of the 1980 peak. In addition, the gill net peak catch 1 l ! occurred only during 1980, while the trawl peak spanned both 1980 and 1981. j I The high 1980 CPUE for gill nets was due to unusually high catches of Atlantic herring and pollock (NAI 1981e). Atlantic herring ranked first in gill net collections during every ) year sampled, comprising from 25 to 82 percent of the total annual catch and averaging 63 percent for all years combined (Table 3.2.2-3). The percent contribution of Atlantic herring to the annual gill net catch was highest in 1978, 1979 and 1980 (74, 80, and 82%, respectively) and lowest in 1984, 1985, and 1986 (26, 25 and 33%, respectively). During all other years, Atlantic herring ranged from 44 to 63% of the total annual catch. In 1987 the percent i of total annual catch for Atlantic herring (52%) was below the 12-year average. Atlantic whiting, blueback herring, pollock, and Atlantic mackerel collectively comprised 27% of the gill not catch for all years combined. l These taxa were fairly consistently ranked among the top five dominant taxa ; during the 12 year period. Blueback herring, which ranked second in percent composition for 1987, was 16% of the total annual catch, the highest level during the 12-year period. Lower ranked taxa (e.g., alewife, Atlantic menhaden, hakes, rainbow smelt and Atlantic cod) comprised a more important portion of the total annual catch during 1984, 1985 and 1986 when catch abundances were below normal and Atlantic herring accounted for a smaller I percentage of the total annual catch. In 1987 none of these species comprised more than 3% of the total annual catch. Species richness ranged from 19 to 31 species annually and totaled 47 for all years combined, with 1987 exhibiting the lowest value (19) in the past 11 years (1976-1986). No ) long-term trend of increasing or decreasing species richness was evident. il 149 i
)
m o t t s 7 os
. 8 b n
...s
- o ri g s.., ot a
s et 6 cs 4 E D N 4 e p m. 8 fl a rl B
, n. ua O
C M
- s. .
s S . 8 5 ,dn N t a t G G 2 G 3 O I _. e N N T
~... n ,
IO T O I T WA l T T S '. eo n A T S S A T A LL T S A
.s
.s.
4
. 8 ni7 ot 8 a9
.
- f t1
- -- - .4 *- os
- .s*\
* .sg .
.. 5 t err
,t
- . # . . 8 sao
.' - . ~
ep
. rye
. u R
~'-g.
s . 2
. 8 oy hb e 4 si n
- H R 2 tl
.,, - A ee E rns
.- 1 Y e a
% pl B 8
ts- g \ l si i 1i \. 't ; t'. g
\
g rik ego ii s *.'; x b o i,*t t'
*.t,.
\ mnr i
.l A 0 uib
! f I
. f .* 1 8 n a
![ s ( d e s eS
!j.! !
s
/ t n
!e;;l ! : .: !/e!i s 9 ri ob .
!e f m7
'. \ 7 f o8 ec9
..*. \v.\' .\
1
.' t s -
i e6
'='.,.' *
- 8 ni7
- 7 uc9 e1 rp
. e sd p e 7 l n
*. hl i s.s' 7 cab t m
'. y af o s'p C oc
* ( 6 7 .
2
- - - - - 2 0 0 0 0 0 0 5 4 3 2 1 2 3
e r u g F@5y
- 2 >E3 - Cn Cn' ZO>4U i F
ewo
P f f A S ) 7 T 8 2 5 6 6 7 2 2 1 3 2 4 9 E 9 5 1 .
< (
N 1 - L L ' - I .
)
G 6 8 3 1 5 8 5 3 5 2 4 2 2 4 N 9 3 1 1 - 1 1 ( I 1 S - E I C E 5 8 5 2 9 2 0 6 6 2 2 1 6
)
4 P 9 2 ~ 2 1 1 1 S 1 ( - T . N7 A8 ) O9 4 D 1 8 6 5 9 0 6 5 5 7 6 3 8 0 U 9 2 1 1 2 B , 1 ( AT R TO SP ) OE '3 - . MR 8 4 1 2 2 5 4 l 1 1 2 7 8 9 4 1 1 i 1 NE 1 ( EN N TI O L I EE T ) HS I 2 2 TA S 8 3 7 0 4 5 2 1 l 1 5 1 B O < 2 9 6 - 1 R P 1 ( OK M FO O O C DR r ) EB 1 NA K 8 5 5 2 8 4 2 1 4 1 1 8 9 IE 9 4 1 1 < . < < 1 BS R 1 ( G. C D E P SE 0 -
)
RN 8 2 6 2 5 2 1 1 1 1 1 1 3 AI 9 8 < < < < < 1 EB 1 ( YI N E LC L A3 9 - 1 G 7 0 4 2 2 2 1 2 1 1 1 5 3 - O 9 8 < < 1 1 AI O I ( A R A2 EG 8 ) Y , 7 4 2 4 1 2 2 1 1 1 1 3 4 - 9 7 1 < < < < 1 Y1 1 ( BG NS ON IO 7 - ) TI 7 8 1 1 4 7 2 3 2 1 1 1 6 ST 9 4 2 1 < < 1 OA 1 ( PT t N S E e CT ) k A 6 a T 7 3 7 5 6 2 1 1 2 1 1 2 0 h N7 9 5 1 1 < 1 E8 1 ( d C9 . e R1 t E t PH o G p LU s AO s TR e d UI I i n TT c a e p e g l n s t 3 g g e e i
- n n n r d r h 2 i i i e a e w r t r k h
- t s h 2 r i r c n s l d e t ,
e h e a e e e o i o d 3 h w h m m i m c c e c s e f r c c k c c e c p o E i i c k i e i p w i s s B t t a c t f t s o t r e A n n b o n i n b n r e d T a a e l a w a e n a e b u l l u l l e l k i l h m l t t l o t l t a a t t u c A A B P A A A N R A O N n i s t.n*
!i
d I Seasonality of pelagic species was analytod in previous' reports , (NAIl1982c;1983b). Two distinct sample groups were observed based on abundances of the dominant species: " summer" (June-August) and " winter" (September-May). Atlantic. mackerel and Atlantic whiting were more abundant ,
.in summer samples, while Atlantic herring were more numerous in winter catches. In 1987 the two summer dominants were more abundant in September j and October, usually characterized.as " winter" months. Blueback herring and pollock showed inconsistent seasonal differences in abundance from 1976 e through 1987.
Spatial Patterns in the Pelagic Fish Community Mean annual catch per unit of effort at the three gill not Stations G1, G2 and G3 showed similar fluctuations across years (Figure'3.2.2-2). Mean annual CPUE peaked in 1980 at all stations. This peak was more evident at Stations G2 and G3 than at Station G1. Percent composition for the dominant species in gill net collections was similar among stations (Table 3.2.2-4). Atlantic herring was the dominant species at each gill not sta-tion, accounting for 58 to 69 percent of the total catch for all years , combined. Blueback herring comprised a larger percent of the total catch at G3 (10%) than at G1 or G2 (6% at each station). Also' numerically important ; at each station were Atlantic whiting, Atlantic mackerel and pollock; each comprising from 4 to 9 percent of the catch at the three stations for all years combined. Depth differences in species composition were analyzed by comparing percent composition in surface nets to that in off-bottom nets (3 m above the bottom) for all years combined (Table 3.2.2-5). Atlantic herring was the dominant species in collections at both depths, with a slightly higher percent contribution in surface nets compared to off-bottom nets. The proportions of blueback herring and Atlantic mackerel were also higher in surface nets. Atlantic whiting, pollock,.and hakes comprised a larger percent of the catch in the off-bottom nets. Atlantic menhaden and alewives l l i 152 l l
-., I TABLE 3. 2. 2-4. TOTAL PERCENT COMPOSITION BY STATION OF ABUNDANT SPECIES COLLECTED IN GILL NETS, ALL YEARS AND DEPTHS COMBINED (1976-1987). SEABROOK BASELINE REPORT, 1987.
l PERCENT COMPOSITION SPECIES G1 G2 G3 l I i Atlantic herring 62 69 58 i Atlantic whiting 8 6 9 Blueback herring 6 6 10 Atlantic mackerel 5 4 5 .j i Pollock 6 5 6 I a Hake species 2 1 1 Atlantic menhaden 2 1 2 Alewife 2 2 2 Rainbow smelt 1 1 1 Longhorn sculpin 1 1 <1 Atlantic cod 1 1 1 1 Bluefish 1 1 <1 All other species 3 2 3 Number of other species (25) (28) (25) includes red, white and spotted hakes i 153 i _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _
TABLE 3.2.2-5. TOTAL PERCENT COMPOSITION OF DOMINANT OILL NET SPECIES ACCORDING TO DEPTil (SURFACE AND OFF-BOTTOM), ALL YEARS COMBINED (1976-1987). SEABROOK BASELINE REPORT, 1987. PERCENT COMPOSITION SPECIES SURFACE OFF-BOTTOM Atlantic herring 69 56 Blueback herring 10 5 Atlantic mackerel 7 3 Atlantic whiting 5 11 Atlantic menhaden 2 1 Alewife 2 1 Pollock 1 12 Rainbow smelt 1 1 liake species a <1 3 Other species 2 7 a includes red, white, and spotted hakes I 154
i l i accounted for a similar percentage in both surface and off-bottom nets. l Trends in 1987 were similar to those encountered during the past eleven years. Since 1980, mid-water nets have been set in addition to the surface l and off-bottom nets during February, June and October. Comparison of CPUE among surface, mid-water and off-bottom nets on dates when all three nets ) were fished revealed that Atlantic menhaden was the only species that was j l slightly more abundant in mid-water catches than in surface or off-bottom catches (Table 3.2.2-6). As was observed with the regular surface and , off-bottom gill net collections, Atlantic herring and Atlantic mackerel were most abundant in surface nets and least abundant in off-bottom nets. Blue- )
)
back herring were also most abundant in surface nets but were least abundant l in off-bottom nets, and intermediate in abundance in mid-water nets. Atlantic whiting, pollock, and rainbow smelt were most abundant in bottom nets. The alewife showed no depth preference, with low CPUE values (<1/ net) at each depth. In 1987, Atlantic herring was most abundant in the off-bottom nets, intermediate in abundance in the mid-water nets and least abundant in surface nets, for those dates when all three nets were fished. Since all three nets were fished only three times during the year and since surface nets shewed a higher abundance than off-bottom nets throughout the rest of the year, the higher bottom-not abundance is probably due to chance i variation. Temporal Patterns in the Estuarine Community 3 Catch per unit of effort for seine stations combined for all species ranged from 60 to 362 fish / haul (Figure 3.2.2-3). Seine CPUE values were lower during the period 1982 through 1986 (60 to 114 fish / haul) than during the period 1976 through 1981 (200 to 362 fish / haul). Annual varia-tions in beach seine CPUE were influenced primarily by annual catches of the Atlantic silverside, which was the most abundant species in seine collections each year (Table 3.2.2 7). The percent contribution of silversides to the total annual seine catch ranged from 47 to 88 percent annually. Atlantic silversido contributed 56% of the total annual catch in 1987, somewhat lower 155
l I h TABLE 3.2.2-6. CATCH PER UNIT EFFORT" BY. DEPTH FOR I1IE DOMIN NT GILL l NET SPECIES OVER-ALL STATIONS AND DATES WHEN SURFACE, ; MID-DEPTH AND BOTTOM NETS WERE SAMPLED, 1980 THROUGH 1987. 'SEABROOK BASELINE REPORT, 1987. k CATCH PER UNIT EFFORT SPECIES SURFACE MID-DEPTH BOTTOM '. Atlantic herring 6;3 3.5 2.3-Atlantic whiting 0.2 0.6 0.8
. Atlantic mackerel 0.9 0.4' O.4 Pollock 0.2 0.1 1.1 l
Alewife . <0.1 ' <0.1 <0.1 ' Blueback herring 1.1- 0.4 0.3 Atlantic menhaden 0.6 0.7 0.2 Rainbow smelt <0.1 <0.1 0.1 number per one 24-hour set of one riot (surf ace, mid-depth or bottom) i l: 1 1 s i , 156 ,. e - _-- _
8 _ d9 e1
.I i 7 t 8 cd en l a l
o4 _ c8 9 4 s1
~-
i 8 e-
'#, - i 6 c7
. e9
. p1 s
, =3 d
, 8 l e l n ai
- b f m oo D - c E 2 N )
=8 e
b O
'.'...'.;'.%. l s un ao C s hi S
N
\*.t'
- s N t 1
S 2 S 3 S O
.*' ,.~_' ea nt I - 1 N N N O AT T .% N i 8 i s O
s.s.s % e I T A OI T A I T S A L
- l: sl l
T T T s S S S A L
. . : X' ;. s ra e
..s. :j s 0 R pd
- s
,'.iq ~
a8 A E Y ra e n
- .' b n mo
~
'.'.1 , ui7
.'t'.
- nt8 a9
,':. ' . .I'e. -
f i 9 7 nt1 s as
.l:li e e l:i.::. e i
m ( rr
,t
/ ao
*'j / s /
8 t ep rye V e7 o A- s f y
- f b e
- % e-
- . s si
- s - t el 7 i ne i- ,
, s i 7 nis
.' uea I*
- :. * \ -
r sB 1,
- i
\'* ~
% ehk s pco
. * ~* ao
- f.1. ,
- 6 her I;!: R- e7 cbb t
- f y a ne
_ CiS
., i 5 7 3 2
_ - - - - - - - 2 0 0 0 0 0 o 0 O . 0 0 0 0 0 o p 0 3 7 6 5 4 3 1 e _ r u g i F n s pEOLmu t73' Eua. rO 4o gR Li~
SD RE AN EI YE ) 7 8 5 4 3 3 3 3 2 2 1 4 K LG LC 6 < 3 ( O A O SR EB NA IE ES 7 S 8 ) 9 f . 1 6 3 2 1 8 0 2 2 2 0 4 2 OD AE 5 < 2 1 ( EN BIl 4 NM I E 8 9 ) . C 1 8 7 1 1 9 1 8 6 3 1 7 4 D 4 < < 1 < 1 T 3 , i I 5 C ) 3 ES LA E 8 9 -
)
D 1 7 8 5 1 4 2 7 7 3 4 3 3 C2 4 < 1 1 5 N 1 S O E s I II T 2 CS I 8 E S 9 ) PS O 1 7 0 7 1 5 8 1 2 6 1 4 2 SN P 5 1 < < 1 O M ( TI I NT C AA E T T ) 1 D S N 8 U E 9 ) BT C 1 8 2 1 1 2 1 4 1 1 1 2 2 AA R 8 < < < < < 1 E ( T) P S6 O8 M91 0 8 N 9 ) E) 1 8 4 1 1 1 1 4 1 3 1 1 9 TM A 6 2 < < < < < < ( E H5 T89 9 R1 7 O 9 ~
)
FG 1 0 3 8 8 5 1 1 1 2 1 2 2 N 6 1 < < < 1 - RI ( AD EU YL C 8 YX 7 BE 9 ) ( 1 5 5 1 1 1 8 5 1 2 1 2 4 N 7 < < < 1 O7 ( I8 T9 I17 S 8 7 OH9 7 PG1 9 ) MU 1 5 3 1 1 5 9 1 4 2 1 1 7 I O , 5 2 < < < < 1 CRT ( h t 1 R s r1O t i P f D6E C7R 6 7 i l - R9 9 ) l E1 E 1 4 5 1 1 4 2 1 1 1 1 3 l i P N 7 1 < < < < < l k GI i LNL d AIE e TRS P UUA TDB i r t s 7 s e d
- k i n 2 c c a e e e e 2 d c b p s 3
i
- s s n
g e s g a l g e r e l n k r n r h E e i i c e i e c v c t d r i d r s h i B l e l n r t n r e t m A i p e a e s u e i o m T s s m s h o h c u s e l e f m c s n c n f k p o i u k e w a i i c s s t l c f o c t p r a r e n u o i b i n s e b r e d a d l w n r a e t e e b u l n l e i e l n n u h m l t u o l a m t i i l t u c A F P A R A A M N B O N n i guO v
than the average for all years combined (67%). Also important numerically were Fundulus species (primarily mummichog), which consistently accounted for more than one percent of the catch (1-23% annually) and ranked among the top five dominant taxa in all years. All other species collected in seines fluctuated from year to year in their ranking and often comp 11 sed less than 1% of the total annual catch. The total number of species collected per year ranged from 19 in 1980 to 27 in 1977. Data for the estuarine fish community for the years of 1985 and 1986 were not included in this year's report. Beach seines were not collected in 1985 and sampling effort was reduced in 1986 (no sampling in April, May and June). Seasonality of the estuarine fish community was analyzed previously using numerical classification (NAI 1983b, 1984b). The estuarine community was highly seasonal in all years, and all three seine stations exhibited similar seasonal changes in their fish assemblages. Catches in the spring were usually characterized by low abundance, and species composition in early summer was highly variable among years. The most distinct group was the late summer-fall assemblage, which occurred yearly from August-November, and in which Atlantic silverside was the overwhelming dominant (NAI 1984b). Spatial Patterns in the Estuarine Fish Community Mean annual catch per unit of effort during the period 1976 through 1983 was usually highest at Station S3 and lowest at Station S1 (Figure 3.2.2-3). During 1984 and 1986, when catches were small relative to earlier years, mean annual CPUE was similar among the three stations, with Atlantic silverside the dominant species at each station (Table 3.2.2-8). Stations S1 and S2 were comparable in their overall species composition, with silversides comprising 55 and 66% of the total catch (respectively) for all years com-bined and Fundulus sp. comprising 13% and 15% respectively. These stations were distinguished from each other and from Station S3 by a relatively high proportion of blueback herring at Station S1 (6%) and American sand lance at Station S2 (4%). Atlantic silverside comprised a larger percentage of the 159
e 7 -e
-f
,I 1
- i. TABLE 3.2.2-8. . TOTAL PERCENT COMPOSITION.BY STATION OF ABUNDANT SPECIES 'f I COLLECTED IN BEACH SEINES,,ALL YEARS COMBINED, APRIL t, THROUGH NOVEMBER.(1976-1984, 1987). SEABROOK BASELINE.
REPORT, 1987. l PERCENT. COMPOSITION 4 SPECIES S1 S2 S3 Atlantic silverside 66' 55 77 ] Fundulus species
- 13 15 <1 1 American sand lance 4 3 2 1 Blueback herring 6 <1" 1, 1 i
l Ninespine stickleback 3 1 3-Atlantic herring 2 5 1
~
Winter flounder 2 1 3- !. Pollock 1 6 5 . 1 y l Gasterosteus species 1 1 1 Alewife 1 10 <1 Rainbow smelt 1 1 6 Smooth flounder <1 <1 <1 All other species <1 <1 <1 Number of other species (22) (19) (25)~ ; i , s includes mummichog and striped killifish. , includes threespine and blackspotted stickleback ! I j l l 160
l } ) i ! l I l catch at Station S3 (77%) than at Stations Si and S2, and mummichogs { ) accounted for o much smaller percentage (<1%). Because of its proximity to l the harbor mouth, onlinity readings were higher at Station S3 than at S1 and i S2 (NAI 1981). Fundulus species prefer a more brackish environment, j exp)aining the larger numbers caught at S1 and S2 than at S3. Rainbow smelt, f 5 l ) a species which prefers a more saline environment, accounted for a larger j percentage of the catch at Station S3 (6%) than at either Station S1 or S2 l (1% for each station). Station S3 was also distinguished by a higher species f
)
) richness (37) than at S2 (31) and S1 (34). Trends in 1987 were similar to 1 i those encountered in previous years (NAI 1988). ! 1 i 3.2.2.2 Selected Species i General i Species selections for examination of seasonal, annual, and spatial j variations in abundance were determined by the following two criteria: high abundance in at least one life stage and gear type, and importance in local commercial or sport fisheries. The nine species selected and their primary collection methods were: Species Gear Type Atlantic herring gill nets Atlantic mackerel gill nets Pollock gill nets Atlantic cod otter trawl llakes (red, white and spotted) otter trawl Yellowtail flounder otter trawl Winter flounder otter trawl and beach seine Rainbow smelt otter trawl and beach seine Atlantic silverside beach seine Comparison of yearly mean catches per unit of effort revealed trends in population size, while comparison of monthly mean catches per unit of effort provided additional information on seasonal cycles. Seasonal and 161
1 annual variability were then used to examine spatial and temporal differ- .! ences. Size-structure of fish populations.also yields important information on. age classes that use the-area and supplies information on recruitment patterns. This information was examined thoroughly in the 1984 Baseline Report (NAI 1985b). Pelagic Species Atlantic Herring -l 4 l Atlantic herring were typically collected in high numbers during , i the spring and fall (Figure 3.2.2-4), with gill net CPUE values greatest March through May and October through December. The 1987 data generally j followed the overall mean with one exception, CPUE for January 1987 was higher than the overall mean. Annuni geometric mean CPUE of Atlantic herring l rose from 1976 (3.4 fish / net) through 1978 (4.9 fish / net), leveled off through 1980 (4.2/ net), and then declined steadily through 1985 (0.6/ net), I the lowest levels observed during the program (Table 3.2.2-9). Annual mean 'f CPUE increased slightly in 1986 and 1987 (0.8 and 1.2 respectively) but were l still below the average mean for all years. A one-way analysis of variance showed significant differences in the yearly log transformed mean CPUE (Table 3.2.2-10). The Waller-Duncan K-ratio t-test for multiple comparison showed that 1978 and 1980, the years with the largest CPUE, were significantly different from 1984-1986, and that 1977 CPUE was significantly higher than that in 1985. j Pollock I Pollock gill net catches were highest during spring and late fall, ; and lowest during winter (Figure 3.2.2-4). The high catches in the spring I and late fall reflected the inshore-offshore movement pollock undergo each year.- CPUE for April, May and August in 1987 were lower than the overall mean CPUE. The low values might have been due to the fact that the gill nets 162 i .l 1
1 l ATLANTIC HERRING i.
, 1.5 -
3 Q. 4 o OVERALL MEAN
- g. g ... .. iss7 ~
w ' I ' 1.0 - .
+ \ .
W
~
o .,
\
l- .3 \ l ., . ) @ 0.5- Y l . . *. ./ \. l
- u. : ..
'. l cn z .
m
' . . . .l
. l 1
' ,:: \..*... ../
.: '. A
- y '
'J g 0.0 , , ,
, . . . 1 i
_, , , i JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC l l MONTH ] 1 l i
)
POLLOCK OVERALL MEAN w 0.5- - .. ~ .- 1987 MEAN - o Q. , U 1 z o,4-w 2 ' 0.3-i / N. ~ 0 ua <- .
- l. .
2 0.2- " .l rz \.' O ! Ik l \ 4' ...'";..~- 5m 0.1 - l \ . c . ..
' i'. . .' . . ' . . * .
3 0.0 I i . .' , , . . . . . JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC i l MONTH l i lI Figure 3.2.2-4. Mean and 95% confidence limits over all years and 1987 values, by month, for log (x + 1) transferred catch per unit effort (one 24-hr. set) for Atlantic herring and Pollock at combined gill net stations G1, G2 and G3 from 1976-1987. Seabrook Baseline Report, 1987. 163
1 R 8596 3 591 0 0597 831 7 481 2 5 9 0 6 6 E CLP NAU EV DR E P 9495 3825 4 3 4843 5335 2 11 3675 6255 0183 31 43 5509 1211 9 1 5 2 4 0 5 0 3 9 2 - IE FIR 2429 8 0692 7860 1606 4381 7 0 2 4 4 NNE 1023 3 3556 6534 1623 7340 6 5 2 3 5 OIH C D 3624 2 0202 3133 2032 0101 0 1 0 0 9 L 2 1 1 RS ER VA 3685 7 4720 4747 6844 0932 2 0 0 4 9 . OE 5159 8 71 99 8043 5898 1 874 2 0 3 4 8 s Y n b 3724 2 2313 4244 2032 1101 1 2 0 0 6 o . NL 2 11 1 i AL t EA a M t s 7 8 9277 9348 0 0 6233 3659 2896 2362 6190 1755 0837 3204 1 6 5 2 4 2 3 2 2 9 l l S a E I C 9 1 4444 1 3278 1 3133 2032 2312 0 1 0 0 9 r o s h E f t P 6 0164 1331 9640 3556 3486 4 5 4 n S H S 8 9 1
. 6750 4324 D
I 5880 41 48 1 1 4234 320 0551 1 011 6338 0100 D I 8 0 1 0 7 0 D I n a e m o 0 m _ I 8 - F a N 5 4588 S 21 07 0138 4401 0474 8 7 7 f I 8 2605 N 8948 2049 9198 3635 S 5 2 4 S ., o - F 9 H N sh 1 3513 4289 3132 0000 0000 0 0 0 nt n ) D 1 on a d - T T i o e e - C 4 1063 t m m l E 8 3366 1 077 1 039 9981 0 5 9 3 0 a p _ 8 7527 8 7066 6458 1631 8641 2 6 1 3 4 t r ) m L 9 sep S a E 1 2523 2 5178 3233 2032 0101 2 0 0 0 9 ( s S 1 l l) s t R . O7 3 9225 0 3271 8917 31 94 1976 7 5 3 ano e n o n F8 8 8 4 3758 9 E1 U 9 9 1 3724 1 0623 8281 4343 3133 9821 3064 4835 1201 4 1 7 1 3 0 6 0 9 2 ft ot o i S e e n - 1 1 1 nb u P , CT a s J R 2 9551 4 3818 3232 6570 2126 5 er s
- O 8 1 5 0 3 mo.h -
3574 9 1236 4393 9769 9270 4 7 2 2 3 st NP 9 denn l _ AE R1 4926 2 2504 6255 31 43 01 01 1 1 0 0 7 ncoo i - ER A 2 1 1 aaim r M E ft p E Y nra3 A CN 3016 7781 + 6 0081 1 0845 5 5 2 7 7 II KL 8 9 4112 9 4690 7 268 8 5'9 3595 1 447 3 7 5 8 7 out4 iss1 ( TE 1 6740 2 0473 7387
. t( s ES 4154 1201 1 1 0 0 4 a lf r 1 1 4 12 2 tll o a P A C B sea e -
E 0 2933 8 8589 911 7 2732 v n y 0003 6 3 6 9 3 h era GK LO AR O 8 9 1 341 3 5750 1 1 6 5 8063 4778 4 22 4189 4233 4467 4185 0683 1101 0 0 2 4 3 0 9 0 0 8 1 cl oe a eren) f m i s u o UB thaG v NA NE AS 9 7 3081 8 9 4320 2792 4091 3373 9 4 3 9 0 at e( i m e r _ 5908 5785 8041 0022 2705 2 8 1 1 7 he t p 9 t ae 2824 4 3411 3133 1 4265 1111 3 2 0 0 6 nf 9 3 22 2 oo,N h t
- m hl i ttl w .
8 _ 2 2801 6 8826 3703 7040 7352 1 9 1 5 4 reni _ 7 8129 0 871 7 6157 7374 661 0 1 8 2 1 5 esoG n _ 2 9 p m o _ 1 2734 3 81 31 6355 3195 1 412 0 4 0 0 9 r t s - 3 1 1 1 2 wurs i .- ooeh r E 7 1 722 t h pt a . L 0 4809 7881 6071 1445 4 2 9 7 7 n p _ B 7 1875 6 3551 5043 2341 7978 7 6 4 3 0 r4l o m A 9 e7 p um o T 1 3413 3 6224 7366 1 01 1 0000 1 3 0 0 8 a c 2 1 1 1 he rh8 3 r - 6 7925 7 0170 71 23 3376 8692 3 3 cpr1 o 7 2735 8 5255 7936 0 5 8 t e f 9 8309 8251 9 4 6 3 0 ahpf 1 1312 1 3400 61 44 1031 1212 1 3 0 0 1 ccth o t a 3 22 3 nacn a _ act a d N e ae O 3 3 3 3 3 3 3 3 3 3 3 mncma dn t . I T 123 - T 5 123 - T 123 - T T T 5 G G G S ) en) ee -
- 1 23 - 123 - - - - - - TmaTli A TTTI 1 TTT1 TTT1 TTT1 TTTI 1 I 1 l I ( eI pc T T 5 T T T T 5 G G C S ) m mi -
S LG l af t W( 1 wsf s d l A 5a u e o e e RT1 rt s r l i c c m d TE Ton - S i r s l i NS nI E e ae e p c cg ce cs R E r _ d td i w i n ir k ir ELNe== I rn wn s t o ti t e c t e TLIt . - C eu ou n b nr nk o nv 1IEtSD E t o l o e a n ar ac - P nl ll k l i l al 0GSOMI l e l a l li _ S if ef a t a th t m o t s t ) ) ) H Y H A R A A P A a bcd H$
m 5 8 - 8 7 T - E 4 9 - O 8 7 - F - F E 6 2 - TK 8 8 IO - f l O - UH 7 7 8 - RA 8 8 - EE - PS t 3 2 6 - t . 8 7 - l 7 . A8 - C9 S - - D-1 t p O 3 8 7 7 - E6 S M79 I l l o1 F R A P 1 8 4 8 SG t NN G AI C RR TU E 9 5
) D L 7 8 P
1D I
+E T L
xN E I U 6 3 B M 7 8 GM DC I C FS 7 6 ON 7 8 O SI RT AA ET 0 1 YS 8 8 GT NE ON 8 0 M 7 8 AL L EI CG N AL IL RA
- A 4 6 2 VR F 2 8 2 O
FF 2 0 2 O S SE II SC 684 235 763 YE S 135 347 865 LP S AS . 572 044 045 N 7 23 ) AH8 1 S9 0) YI1 1 AF 0. 0 MN , IT f 11 2 112 112 00 EFR B O d 134 11 134 11 134 1 1 1
> 0 C DP p6 EE 1 FTR OC )
50 02 p SLN EE F N O O 1 t TEI I srl srl srl 0.> 0 t LSL U E E T C A roa art roa art roaart 0 p0 a
.n SRS EOA R I ero ero ero > ( c U R YET YET YET p2 i RFB O A tf S V I 5 ni
. t 0. ancg 0 n0ii 1 a( fs
- c i 2 l it ny g e f n gl 2 n r i aih i e ncsg 3 r k gi i r c i fyh E e a sil L h m nh y B t ggr A c c oiie T S i i k nshv E t t c I n n o = = ==
C a a l E l l l S*** P t t o N ** S A A P
- gmw l lllll ,t
were only set once a month for two days, thus decreasing the chances of the fish being encountered. Annual mean CPUE (all stations combined) for pollock varied from 0.2 to 1.0 fish / net and averaged 0.4 fish / net over all years (Table 3.2.2-9). The 1987 mean CPUE of 0.2 fish / net was one of the lowest encountered during the study period. A one-way analysis of variance showed a significant difference in the log-transformed CPUE among years (Table 3.2.2-10). Waller-Duncan's multiple comparison revealed that 1982, 1979, and 1978, the years with the lowest CPUE, were significantly different from 1980 and 1981, and that the 1987 CPUE was significantly lower than that in 1980 (the highest year). Atlantic Mackerel Atlantic mackerel were present in gill not collections primarily from May to November with low CPUE January through April (Figure 3.2.2-5). Following a gradual increase in abundance May through July, monthly mean CPUE leveled off and remained at similar levels through November. In July and August of 1987, no Atlantic mackerel were caught, which may have been due to the infrequency of the gill not collections. Catches in September and October were greater than their overall means. Catches for mackerel were variable over the years, with mean CPUE ranging from 0.1 to 0.6 fish / net, and averaging 0.3 fish / net (Table 3.2.2-9). The one-way analysis of variance showed no significant differences among yearly means of log-transformed data (Table 3.2.2-10). Demersal Species Atlantic Cod Atlantic cod were usually present in otter trawl catches throughout the year, with the highest catch per unit of effort (CPUE) in April, May and October through December (Figure 3.2.2-5). The 1987 monthly CPUE at T2 166 I
3 3
.)
r ATLANTIC MACKEREL o 0. o
- k. O.4 OVERAU.MEAN ..,,,,,**.'r
...... .7 c ,
2 - s $,
? ! '. ..
$ 0.3- ! i,
{a J
~ !
i o '
---- i
{ g a: 0.2 - , s ! i* l O e i E .
,/ . 8 e
m i i z e
\ ! '
y 0.1 - ,/ \, /
"g
* . \ ! 'N I C \ ! \ l O p r \
f,
\
J 0.0 , , , , , , , , , JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC W 1 MONTH l w ATLANTIC COD i o 1.2-i Q. j u . , 1 2 1.0 - .. 1 l w a -- OVERAU.MEAN 0.8-y ,, j',,, . . _ . . 3,87 (n, oa o,t ) i 5 l \ 8 x a: S-
/ .
I.. l
.r
@ 0.4 - ., /
i E '.'
.i . .. .. / /l .
5 0.2-M'/ .'! l e O '
.. \ :
y/ a 0.0 , i , , i , , , a JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH i Figure 3.2.2-5. Mean and 95% confidence limits over all years, and 1987 values, by month, for log (x + 1) transformed catch per unit effort (one 24-hr. set for gill nets, one 10-min. tow for otter trawl) for Atlantic mackerel at combined , gill net stations G1, G2 and G3 and Atlantic cod at otter trawl station T2, 1976-1987. Seabrook Baseline Report, 1987. 167
l followed this trend, with peaks in May and December and low periods of abundance in February and March and June through August. No October data were collected in 1987 at T2 because lobster pots in that area prevented trawling. In addition, no cod were collected in November, generally a peak period for this species. Length-frequency data analyzed in past years showed that the spring peak was primarily comprised of immature (age one and two) cod, while the fall peak consisted of young-of-ths-year (age 0) to age five (NAI 1985). The annual mean CPUE (geometric mean averaged over the three stations) for cod rose from 1.1 fish / tow in 1977 to greater than 5.2 fish / tow from 1978 through 1980 (Table 3.2.2-9). Mean CPUE gradually declined from 1981 through 1985, the lowest IcVel recorded during the study (0.8 fish / tow). However, mean CPUE increased in 1986 and 1987 (1.2 and 2.5 fish / tow, respec-tively), indicating a possible reversal in the low abundances. A one-way analysis of variance revealed very highly significant differences among years at Station T1 (Table 3.2.2-11). The Waller-Duncan multiple comparison test showed that 1978 through 1983, the years of high abundance were significantly different from 1977, 1985 and 1986, the years of low abundance. Hakes Hake species (red, white and spotted) were present in high numbers at Station T2 from March through November, and in low numbers from December through February (Figure 3.2.2-6). Hake CPUE increased slowly in March through May, reaching a peak in June through October and then decreased in November. In 1987, mean CPUE followed this general trend. Although catches in May and June were lower than usual, CPUs from July through September were greater than the mean CPUE for all years. Annual mean CPUE (all three stations combined) ranged from 7.9 fish / tow in 1981 to 3.0 fish / tow in 1985, averaging 4.4 fish / tow overall (Table 3.2.2-9). In 1987, mean CPUE (3.3 fish / tow) was lower than the 12-year mean. The results of a one-way analysis of variance showed no significant differences in catch among years (Table 3.2.2-11). 168
l HAKES l w 1.2 - l D i G* U " Z 1.0 - ,-., .
< w *
/ *..'.. *..-
i 2 / .. N _ 0.8- f' I f i 1 5 .. l o 0.6 - ,,
/
w 2 / m l - o u 0.4- ! g cc H 0.2 - *
/7 . ;:/
/ *
,/ ' OVERALL MEAN
/ - --- . 1987 (no Od data) 8 V, : ... *.*..
a 0.0 , , , , , , , , , JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH l YELLOWTAll FLOUNDER 2.0 - m a- 1.8 - U Z 1.6 - OVERALL MEAN 2 1.4 - , j ., 1987 (no oc data)
'.'.?s/ ".
+ 1.2 - '
5
- 1.0 - . "
C . - '
$ 0.8-
- cc .
O 06- - V*.., u,.
- E
< 0.4 -
y / m .
& 0.2 - '. .
0 O 0.0 , , , , , , , , , , i 1 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH Figure 3.2.2-6. Mean and 95% confidence limits over all years, and 1987 values, by month, for log (x + 1) transformed catch per unit effort (one 10-min. tow) for hakes and yellowtail flounder at otter trawl station T2, 1976-1987. Seabrook Baseline Report, 1987. l l 169
*6 7 5 7 8 8 9 6 6 7 8 8 T
I NK 4 5 7 UO 8 8 7 O RR EB PA 8 4 6 t S E 7 8 7 O T A . 7 3 4 C7 7 8 8 8 D9 E1 S M - N 5 8 7 R6 O 8 7 8 O7 S F9 I S1 R N A 3 2 8 AG P 8 8 7 RN M TI O R C ) U 1 D 2 7 2
+ E 8 7 8 x1 P
( T I GN T _ L OO U 6 6 3 LI H 8 7 8 T FA OT S S 7 9 9 RL 8 7 7 AN EA YR T G 0 1 1 NR 8 8 8 OE MT AI C 1 0 0 E 8 8 8 CT NA A IS RE AI VC FP E 6 1 "2 1 OS F 8 7 5 3 6 SH 4 6 0 3 0 IS SI YF LN AI . 61 7 886 820 437 976 NF7 S 538 1 46 977 921 61 8 A 8 S D9 268 471 1 79 348 1 34 YE1 1 44 1 1 33 AT ) MC , 1 ET 01 ELR 01 NEO 0 OSP f 1 23 1 23 1 23 1 23 1 23 00 E d 134 1 34 1 34 1 34 1 34 FRR 1 1 1 1 1 1 1 1 1 1 > 0 OO ) FE 1 p6 S N TTI LkL FN
)
50 02 p UOE OO t SFS I srl srl srl srl srl 0.> 1 EFA REB ET CA roa art roa art roa roa roaart 0 0. nt RI ero ero art ero art P0 a UR YET YET ero ero > ( c
. OA YET YET YET 2 i p tf 1 SV t 5ni 1
2 t 0.cang r n0ii 2 e a( f s c i 3 d it ny n f ngl r u iaiL e o ncsg E d l t gi i B n f d l ifyh A u o e sil T o l c m nh y l i s t ggr f a c oiie S t i w nshv E r w t o I e o s n b = * = = C t l e a n E n l k l i S* *
- P i e a t a N *
- S W Y H A R
- wO l
1 i
'1
-1 j
I Yellowtail Flounder i Yellowtail flounder were collected year round in otter trawls at-j' Station T2 (Figure 3.2.2-6) with monthly CPUE lower in June through' September- ] than in October through May. During June, August, and September of 1987, i yellowtail CPUE was zero,.well below the mean CPUE for these months over all years. No October data were collected in 1987 due to lobster pots in the ] trawling area. No distinct seasonal differences were noted for Stations T1 : and T3 (NAI 1986). Analysis of length-frequency data in previous years revealed the majority of individuals collected at Station T2 were young-of-- the-year fish (< 18 cm) and were most abundant'during November through March (NAI 1984). The low summer CPUE at T2 probably reflects the movement of these young-of-the-year. fish to other. areas. Annual'mean CPUE-(all three stations combined) ranged from 28.4 fish / tow in 1980 to-8.0 fish / tow in 1986. In 1987 CPUE-increased slightly (8.9 fish / tow) but was still below the- 1 ovet-all year mean of 13.9 fish / tow (Table 3.2.2-9). Mean CPUE was greatest at Station T1 (22.7 fish / tow), intermediate at Station T3 (11.9' fish / tow).and lowest et Station T2 (3.2 fish / tow). The one-way analysis of variance among j years was very highly significant, and Waller-Duncan's multiple comparison of yearly means showed six overlapping groups with 1987 CPUE significantly lower than in six of the 11 previous years (Table 3.2.2-10). 1 Demersal and Estuarine Species l Winter Flounder Winter flounder were present in otter trawl collections year-round, 1 though not always at all three stations (NAI 1986). No distinct seasonal' , trend was apparent at Station T2, except mean CPUE was lowest in December and January (Figure 3.2.2-7). In 1987, CPUE for November, December and February l were all below the overall mean. No October data were collected in 1987 due to lobster pots in the trawling' area. ' Annual m-an CPUE (all three stations combined) increased from a low of 2.6 fish / tow in 1976 to'10.3 fish / tow in j
-{
171 ;
l l WINTER FLOUNDER (TRAWLS) w 1.4 - . m !
- a. ..
u 1.2 - 2 - 4
$ 1.0 - # -
%#N .
w* . '. ...h yu 0.8 - '
,/ ... . .. ..u...
/ y-
..f . ..
e :
$ 0.6 - / a. .
. ...... . ., 3 O '.*
I
$ 0.4 - ,
x '. J' 1 g OVERALL MEAN *
- p. 0.2 - ,,,,,,,
,7 g o, ,,,)
8 a 0.0 , , , , , , , , , , , , JAN FEB MAR APR MAY JUN JUL AUG SEP OCT to/ TC MONTH
'l l
w 1.0 - WINTER FLOUNDER (SEINES) i 3 . J Q-1 o .
$ 0.8 - ,
W ; m. E -
/ *.
$ 0.6 - j
'. /
5 '. l. '. e . . l . 1 W '
/ * * * '
2 0.4 - /
- E l o
. . , -i E *
'. *./ .
I w : *<
~ .
Z g 0.2 - -
.4 OVERAU.MEAN
,. ... .. 1987 .
g 0.0 a i , , , , , , j APR MAY JUN JUL AUG SEP OCT NOV MONTH Figure 3.2.2-7. Mean and 95% confidence limits over all years, and 1987 values, by month, for log (x + 1) transformed catch per unit effort (one 10-min. tow for otter trawls and one i haul for beach seines) for winter flounder at otter trawl station T2' 1976-1987 and combined beach seine stations S1, S2 and S3 1976-1984 and 1987. Seabrook Baseline Report, 1987, 172
l-1' 1980 and 1981, averaging 4.9 fish / tow over the 12-year period (Table 3.2.2-9). Annual mean CPUE declined from 1982 through 1985 but increased in 1986 and 1987 to present levels of 4.9 fish / tow. Mean CPUE values were l l highest at T2 (7.2 fish / tow) followed by Station T1 (3.5 fish / tow) and Station T3 (2.6 fish / tow). Results of the one-way analysis of variance among ) years was very highly significant (Table 3.2.2-11). The multiple comparisons of yearly catches showed 1976 was significantly lower than all other years. Winter flounder were also present in beach seine collections from the Hampton-Seabrook estuary throughout the April through November sampling period (Figure 3.2.2-7). In 1987, monthly mean CPUE was much lower than average for all months except June and August. Annual mean CPUE (all three stations combined) ranged from 1.0 fish / tow in 1987 to 5.7 fish / tow in 1980, with an average of 2.9 fish / tow (Table 3.2.2-9). A one-way analysis of variance among years was highly significant, and the multiple comparisons of yearly catches showed 1980 and 1979 to be significantly higher than 1976, 1983, and 1987, ar.d 1987 CPUE to be significantly lower than that in all years except 1976 and 1983 (Table 3.2.2-12). Beach seines were not collected in 1985 and insufficient data were collected in 1986 to use in this comparison. I l l Rainbow Smelt Rainbow smelt were collected in otter trawls primarily during December through March (Figure 3.2.2-8). In 1987, monthly mean CPUE followed this same pattern except catches in November and December were higher than normal. Annual mean CPUE (all three stations combined) ranged.from 2.9 fish / tow in 1978 to 0.5 fish / tow in 1985, averaging 1.4 fish / tow overall (Table 3.2.2-9). In 1987, mean CPUE (2.5 fish / tow) increased over 1986 values (0.9 fish / tow) indicating a possible reversal in the low abundances experienced in 1985. Mean CPUE was greatest at Station T2 (1.9 fish / tow) followed by Station T1 (1.1 fish / tow) and Station T3 (0.7 fish / tow). Results of a one-way analysis of variance showed no significant differences in catch among ysars (Table 3.2.2-11). 173
7 0 7 0 8 F F E . 7 6 T8 I9 7 N1 U Rl s 3 8 EA P Ht M 4 C9 8 T1 A - C6 S 7 N 2 D9 O 8 E1 S M I l G l R oN A 1 FI P 8 5R t N NU I AD C R TD E 8 7 ) E P 1D I
+B T L
(xG C U 7 7 M G OS LN O FI 9 OT 7 A ST t l S A EE 0 YN 8 I GE NS O MH AC A EE CB N AL IL
- RA
- A 4 2 1 VR F 4 0 3 O .
FF7 3 1 0 O 6 S9 SE1 II SC , 166 921 361 YEE LPI S S 785 731 292 ASO 135 21 4 304 N P 22 88 ) AHE SR 1 YI 0) AFE 1 MNN 0. 0 II f 909 909 909 00 EFL d 77 77 77 N E )
>0 ODS EA 1 p5 FTB 02 p OC )
F N 50 SEK TEO O OO I srl srl srl 0. > 1 ( LSR E T roa roa roa 0 0. nt U B C A art art art P0 a SRA R I ero ero ero > 1 c EOE U R YET YET YET 2 i RFS O A ' p tf S V ( 5ni 0 an
. t cg 2 s n0ii 1 e aE f s - d c i 2 i it ny s fngl 2 r r iaih e e ncsg 3 d t v gi i n l l i fyh E u e i sil L o m s nhy B l s t ggr A f c oiie T S w i nshv E r o t I e b n = = ==
C t n a E n i l S
- P S
i W R a t A M * ** ** g w v.
l l i l RAINBOW SMELT (TRAWLS) w 2.2 - , i :p . 0- 2.0 - / U l l z 1.8 - OW.RAU. MEAN / l 4 ... .. 1987 (no Od data) / y 1.6- ,/ I
;:- 1.4 - .,
+ "
( 5 1.2 - " a ; w 1.0 - y J E . 1 2 0.8-
- O '
l
$ 0.6 - ' .* . . * '
1 2 . 4 0'4 - . i lE \ ..
/ j g
a 0.2-0.0 , , , v ... a 4.. . '::- x-s s s a : JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ! i MONTH i 1 I RAINBOW SMELT (SEINES) w 1.8 - l :D . I 1 c. . l O 1.6 - j'., ; k w j4 fk
- ON MN 1987 j l E l \ l 1,2 -
_ l \ 7 l . l 1 o 5 1D' l l \\ . W 0. 8 - ! ' E l \ ., 0; ; \ .. O 0.6 - l
~
u .
\.e 1
m i
"'~
0.2 - l l .
\
/ N/
c '
- O 0.0 , , . . .
APR MAY JUN JUL AUG SEP OCT 'NOV MONTH Figure 3.2.2-8. Mean and 95% confidence limits over all years and 1987 values, by month, for log (x + 1) transfored catch per unit effort (one 10-min. tow for otter trawl and one ; haul for beach seines) for rainbow smelt at otter trawl station T2 1976-1987 and combined beach seine stations S1, S2,' S3 from 1976-1984 and 1987. Seabrook Baseline l Report, 1987. 175 l l
i l I
- j 1
Rainbow smelt were also prevalent in beach seine collections in the llampton-Seabrook estuary. Monthly CPUE was variable with large catches possible any month during the sampling period (Figure 3.2.2-8). In 1987 no I fish were caught from June through November. Annual mean CPUE (all three f stations ccmbined) ranged from 0.1 fish /scine in 1980 to 3.3 fish / seine in 1979, averaging 1.2 fish / seine (Table 3.2.2-9). In 1987 mean CPUE decreased from 1984 values to the third lowest value during the past 12 years (0.6 g fish / seine). Station differences were evident, with mean CPUE much higher at Station S3 (1.7 fish / tow) than at either Station S2 (0.2 fish / tow) or Station ; S1 (0.1 fish / tow). A one-way analysis of variance on the yearly log- i transformed CPUE showed no significant difference among years (Table 3.2.2-12). i l l 1 Estuarine Species
]
Atlantic Silverside g i Atlantic silverside were present in the llampton-Seabrook estuary beach seine collections throughout the April through November sampling season { in most. years, with the largest CPUE values occurring from August through l November (Figure 3.2.2-9). The CPUE for 1987 followed this pattern, except September was much lower than the overall mean. The catches were highly variable throughout the years with annual mean CPUE ranging from 7.3 to 31.1 ; fish / haul and averaging 16.9 fish / haul overall (Table 3.2.2-9). The high variability might be due to the high mobility and schooling characteristics of this species. The one-way analysis of variance showed no significant j difference among years for log-transformed CPUE (Table 3.2.2-12). ) i 1 l l l l l i
-i l 176 1 1
i
l 1 ATLANTIC SILVERSIDE 2.8- ,
~
l l l 2.4- .. m /
\.,
@ 2.0- , j j u .
l '., z '.' . , l '. .l W
* /
/ '. .
1 I '. s
- p. 1.6 - ',
l g ; - V o l < W . l l x : i l g 1.2- l a . m z . 4 :
- I CC
& l l c 0.8- !
O l l 0 ' l l ' j OVERALL. MEAN
/ '. ' " " "
- 1 0.4 -
- 1
./ '.
-l l W 1
( ., ,
. l l .
0.0 , , , , , , , , l APR MAY JUN JUL AUG SEP OCT NOV j l MONTH Figure 3.2.2-9. Mean and 95% confidence limits over all yer;s, and 1987 values, by month, for log (x + 1) transformed catch.per : unit effort (one haul for beach seines', for Atlantic- f silverside at combined beach seine' stations S1, S2 and. ' S3 1976-1984 and 1987. Seabrook Baseline Report, 1987. 177' ! i
- _ - 2_._._.__ _ _ _ . _ . _ _ _ . _ _ _ _ _ _ _ _ _ _ . _ _
l 3.2.3 Finfish Appendix Tables i l
=
178 ;
APPENDIX TABLE 3.2.1-1. FINFISH SPECIES COMPOSITION BY LIFE STAGE AND GEAR, JULY 1975-DECEMBER 1987. SEABROOK BASELINE REPORT, 1987. ICHTHY 0- ADULT AND JUVE-PLANKTON NILE FINFISH l TOWS I GILL a a SCIENTIFIC NAME COMMON NAME EGGS LARVAE TRAWLS NETS SEINES Acipenser oxyrhynchus Atlantic sturgeon R Alosa aestivalls blueback herring R C C Alosa mediocris hickory shad R Alosa pseudoherengus alewife 0 0 0 Alosa sapidissima American shad R 0 0 Amn.odytes americanus American sand lance A 0 R 0 Anarbichas lupus Atlantic uolffish R Anchos hopsetus striped anchovy R Anguilla rostrata American eel C R Apeltes quadracus foutspine stickleback R Archosargus probatocephalus sheepshead R Aspidophoroides monopterygius alligatorfish C 0 Brevoortia tyrannus Atlantic menhaden 0 0 0 R Brosme brosme cusk 0 0 Caranx hippos crevalle Jack R Centropristis strinta black sea bass R R Conger oceanicus conger eel R Clupea harengus barengus Atlantic herring C 0 A 0 Cryptacanthodes maculatus wrymouth 0 Cyclopterus lumpus lumpfish C R R R Enchelyopus cimbrius fourbeard rockling C C 0 Tundulus sp.* mummichog* C Gadus mothua Atlantic cod - C C 0 R (continued) 179 l
l l 1 l APPENDIX TABLE 3.2.1-1. (Continued) l ICHTHYO- ADULT AND JUVE- l l l PLANKTON NILE FINFISH i TOWS l a a GILL ! SCIENTIFIC NAME COMMON NAME EGGS LARVAE TRAWLS NETS SEINES Gadus /Helanogrammus Atlantic cod / haddock C - - - - d Gasterosteas sp. stickleback R C Glyptocephalus cynoglossus uitch flounder C C 0 Hemitripterus americanus sea raven 0 0 0 R Hippoglossoldes platessoides American plaice C C 0 1 Hippoglossus h1ppoglossus Atlantic halibut R Labridae/Limanda cunner /yellowtail flounder
- A - - - -
Limanda ferrugines yellowtail flounder - C A R 0 Llopsetta putnami smooth flounder R R C Liparis atlanticus seasnail C Liparis cohnni gulf snallfish C - - - Liparis sp.' snailfish' - 0 Lophius americanus goosefish C 0 R Lumpenus lampretaeformis 8 snakeblenny 0 R Lumpenus maculatus da'nbed shanny R R Hacrozoarces americanus ocean pout 0 C R Helanogrammus aeglefinus haddock - 0 C B Henidia menidia Atlantic silverside O R A Menticirrhus saxatills northern kingfish R h Herlucclus bilinearls Atlantic uhiting g g g g y (continued) 180
+.
t b !.; APPENDIX TABLE 3,2.1-1. (Continued)l I i ICHTHYO- ADULT AND JUVE- ) PLANKTON NILE FINFISH l
, TOWS GILL a
l SCIENTIFIC NAME COMMON NAME' EGGS LARVAE TRAWLS NETS. SEINES. h.
#1crogadas toscod Atlantic tomcod R' ,0
[ Morone americana white perch R i l Horone saxatillsI striped bass' R R j Mustelus canis smooth dogiish_ R' Hyoxocephalus aenaeus grubby C 0 R O' j- Hyoxocephalus octodocesspinosus- longhorn sculpin C A 0. R- l Hyoxocephalus scorplus shorthorn sculpin 0 0 R R \ Odontaspis taurus sand tiger R Oncorhynchus kisutch coho salmon R R Osmerus mordax rainbou smelt C C 0 C ' Para 11chthys dentatus summer flounder .R Paralichthys oblongus toutspot flounder o C Pepellus triacanthus butterfish o O R 0 ^R Petromyzon marinus sea lamprey R Pholls gunnellus rock gunnel C 0 R R Pollachlus virens pollock C C C C 0 Pomatomus saltatrix bluefish 0 R' Prionotus carolinus northern searobin - - 0 R Prionotus evolans striped searobin. - - R
'Prionotus sp, searobin 0 'R - - -
Pseudopleuronectes americanus winter flounder C C 0 C Pungitius pungitins ninespine stickleback C Raja sp.I skate C R Salma galvdneri rainbow trout R: (continued) 181 ,
APPENDIX TABLE 3.2.1-1. (Continued) ICHTHYO- ADULT AND JUVE-PLANKTON NILE FINFISH TOWS a a GILL SCIENTIFIC NAME COMMON NAME EGGS LARVAE TRAWLS NETS SEINES Salmo trutta brown trout 0 Salvelinus fontinalis brook trout R Scomber japonicus chub mackerel R Scomber scombrus Atlantic mackerel A A *R C R Scophthalmus aquosus uindoupane C C C R 0 Sebastes sp.) redfish 0 Sphaeroides maculatus northern puffer R R Squalus acanthias spiny dogfish R R Stenotomus chrysops scup R 0 R Stichaeus punctatus Arctic shanny 0 Syngnathus fuscus northern pipefish C 0 R 0 Tautogn onitis tautog - 0 R Tautogolabrus adspersus cunner - A 0 0 R Torpedo nobiliana Atlantic torpedo R Triglops .nurray1 moustache sculpin > R Ulvaria subbifurcata radiated shanny V O Urophycis sp. hake A C A 0 C Footnotes: See next page. 182
( ) ( APPENDIX TABLE 3.2.1-1. (Continued) Footnotes:
" Names are according to Robins et al. (1980) unless otherwise noted. Taxa
, usually identified to a different level are not included in this list to avoid I duplication (e.g., Gadidae, Encholyopus/Urophycis, Hyoxocephalus sp., Urophycis chuss, etc.) b l occurrence of each species is indicated by its relative abundance or frequency l of occurrence for each lifestage or gear type: A = abundant (2 10% of total catch over all years) C = common (occurring in 2 10% of samples but < 10% of total catch) 0 = occasional (occurring in < 10 and 2 1% of samples) R = rare (occurring in < 1% of samples)
- = not usually identified to this taxonomic level at this lifestage
'Predominantly Fundulus heteroclitic, mummichog, but may include.a small number of Fundulus majalls, striped killiftsh.
d Two species of Casterosteus have been identified from seine samples: U. aculeatus, threespine stickleback; and C. ubeatlandi, blackspotted stickleback (both occurring commonly).
*May also include a small number of tautog.
I Three species of Liparis have been identified from trawl samples: L. atlanticus, L. coheni, and L. inquilinus (inquiline snailfish). 8 Spelling after Faber (1976). h Previously called silver hake (NAI 1982a); Atlantic whiting was recommended by Kendall and Naplin (1981:707). I Four species of Raja have been identified from trawl samples: R. radiata, thorny skate (common); R. erinacea, little skate (common); R. binoculata, big i skate (occasional); and R. eglanteria, clearnose skate (rare), d Previously called S. marinus. Recently S. mente11a and S. fasciatus have also been reported to occur in the northwest Atlantic (Ni 1981a; 1981b). Sebastes in coastal New Hampshire waters are probably S. fasciatus (Dr. Bruce B. Collette, U.S. National Museum, pers. comm. April 1982), but larval descriptions are insufficient to allow distinction among the three species. k Three species of Urophycis have been identified from trawl samples: U. chuss, red hake (common); U. tenuls, white hake (common); and U. regio, spotted hake (rare). l l l 1, 183 l l
L } 3.3 BENTIIOS 3.3.1 Estuarfne Benthos 3.3.1.1 Physical Environment Salinity and Temperature ) Weekly measurements of salinity and temperature at high and low slack tides in Brown's River and llampton Harbor were taken to investigate annual and monthly patterns. The Brown's River salinity station is just downstream from the benthic transect, and about 0.5 km downstream from the settling basin outfall; the IIampton liarbor station is a control station away from the influence of the outfall (Figure 4.1-4). Low tide collections in Brown's River represent the more extreme environmental conditions in compari-son to llampton liarbor. The water is not as terrpered by tidal influx of sea ) water, as is the liampton liarbor station. Mean monthly salinity at low tide in Brown's River ranged from 17.5 i 4.6 ppt in April to 25.3 i 1.6 ppt in August during the nine year study period from May 1979 through December 1987 (Appendix Table 3.3.1-1, Figure 3.3.1-1, Table 3.3.1-1). In 1987, monthly salinities were within the 95% confidence limits of the nine-year averages except for April, May, and September, which had below-average salinities (Figure 3.3.1-1). Rainfall during April 1987 totaled 9.5 inches (Table 3.3.1-2), and nearly half of that occurred on April 5 and 6 (National Climatic Data Center 1987), which caused flood waters to reach a 10-year high in many New llampshire areas. Rainfall in late April was also well above average, which caused the mean salinity in May 1987 to be well below the nine-year average, despite a total rainfall of only 1.75 inches. Again in September, the total rainfall was very high, and salinities were correspondingly low. In spite of having salinit les which , fell below the lower 95% confidence limit of the nine-year average during three months of 1987, the annual mean salinity was 20.1 ppt, only very ' slightly below the average for the study period (Table 3.3.1-1). Likewise, j the annual precipitation was 45.5 inches, slightly above the average for the study period (42.18 inches). 185
Salinity 30 - 25 - e, ['/ ^ , - y..;,. Q ...- g 20 - y.. ., __. /.. . ..... . * > 15 - '.,
- E v a
< 10 - M OVERAU.MEAN
... .. 1987.
5-0 , , , , , , , , , , , , JAN EB MAR APR MAY JUN JUL AUG SEP OCT t m CEC MONTH Temperature 25 - 20 - / p.... g...... N. 6 2, h \, i w 15 - / a: - D . w .
* . .\
2 10 - - w .,
- n. -
2 ' N *t . b\. 5- ovanAu.MEAN \
. .. ,/ ... .. ,w 0
.y -
, , , ., e -
JAN FEB MAR APR MAY JUN JUL AUG SGo OCT PG Drg MONTH j i Figuro 3.3.1-1. Mean monthly seawater surface temperature and salinity with 95% confidence' limits teken at low tide in Brown's 1 River over the entiro study per.tod (May 1979 - December 1987) and in 1987. Ganbrook Baseline Report, 1987. 186 l
4 - t G R F
)
E - D I T K EIt DL Mt My p 1 2 3 5 1 3 2 1 3 1 0 3 2 0 3 2 2 3 5 1 3 7 0 3 2 1 3
. IA C7 TS A8 L9 H S1 G 3 I
N I IT 3 2 9 4 4 9 4 IR M yC ~ 9 i 1 1 R O 9 9 9 9 0 9 8 9 OP D E O B 1 - AR R A - HE GE H ID N ' ML U E I HS F Yl TA Tt 9 9 3 5 8 1 7 5 7 OB I A I p . B M My- 9 8 7 5 6 9 7 7 7 d ._ e TOK I 2 2 2 2 2 2 2 2 2 L t t - - AO EA u - E R DS I p - m DB A T o __ K E c TAS H s D D
) 6 3 2 4 4 6 0 0 1 a -
. w T7 P 8 L yC i 9 9 0 1
0 1 0 1 0 1 0 1 0 1 0 1 n P 9 a (1 e
- m .
Y0 . T8 l - I 9 a . I M1 u Lt Y n Tl c n AG SR I t M 0 0 0 0 4 6 2 7 6 a . p F I Lp 1 0 0 8 8 0 0 8 9 os _ O D R AE 3 3 3 2 2 3 3 2 2 nh t AO ES e n B D r o
)
CA R I T f om H el I H rI G e EM RI I l 6 3 9 0 6 1 6 b
- 2 h =
t - UP ,n TM AA R H yC t 9 0 1 9 1 1 0 1 0 1 9 0 1 y e - RH E r r E V e a o PO MD I R r uf r e EA u b r T R S t a e e r F h E N t
'M V H Y e r AI ER O
R T I) c1 s o , H L* S B Mt Ip Lp 1 5 2 5 5 2 8 2 2 4 9 1 1 8 1 7 1 2 4 0 2 0 2 6 1 2
" - hno t y r r a a u y
At AE n munbr - Um ES a e 2 a e I o D SR I m 1 JF IAB T y n n N l i i
. D h 1 L ) b t n n n
- 9 6 7 9 9 3 3 - 1 e e 1 pC 0 0 0 1 1 1 0 1 o
n k k a a 3 Tt 1 1 1 1 1 1 1 1 I t t
=
3 e e n r r E a e e L B e ww m A a a T L l t t L a a a 0 8 1 8 2 8 3 8 h t 5 8 6 8 7 8 A R u n d d e 9 9 9 9 9 9 9 9 E h o o 1 1 1 1 1 1 1 1 V A N N O a b C '_ H$
~
Wa - C, _ . u - -
~
e _ , C: J
! 1
7 3 2 7 6 5 2 2 3 9 3 9 2 8 8 2 7 2 4 7 6 8 9 2 7 4 1 4 9 1 7 0 4 9 1 2 0 2 7 2 3 2 5 4 L A R O I T 5 2 3 2 9 1 4 6 2 8 7 1 8 3 A 8 4 8 5 3 7 9 3 0 2 0 3 3 .
*) . 9 4: r R 7 1 3 2 3 1 1 7 3 3 1 3 6 6 4 e E 8 4 b T 9 m N1 e I
, c N T e A R D GO 5 2 3 9 2 6 4 1 7 0 5 9 1 9 y O P 8 1 8 2 6 3 9 5 6 0 6 3 2 5 r L E 9 a R 1 1 1 2 1 3 3 3 6 3 1 6 1 6 u T 3 n A E a
. N J - N I E L y K E r A S a T A 4 1 1 2 3 7 6 3 0 2 8 8 3 4 m B 8 3 8 8 4 7 0 4 6 2 1 6 9 2 m R 9 u A K 1 2 7 6 4 8 3 4 1 1 5 1 2 0 S E O 5 Y O y R l OBA P h t A E n I S o 3 3 0 2 6 4 7 7 8 6 4 9 4 D 8 0 0 7 8 9 0 2 0 M 0 0 7 8 9 6 N
- 9 ,
O 1 5 5 9 6 2 1 3 3 8 3 a M 7. 1 1 4 8 5 t Y 9 S I a B 1 A D T
)
R l S E U a 1 c E H S. Y 2 8 9 6 6 6 7 1 2 4 8 5 2 0 2 2 2 2 7 9 2 7 1 i 5 1 4 2 6 g C N C U L H 9 2 o _ 1 4 2 3 2 3 4 2 1 3 3 1 4 l I E T 1 4 o D N t N O a I - M m T i ( 8 7 l O9 L1 1 3 5 9 5 2 4 7 5 7 4 4 3 8 7 1 C 6 6 1 1 6 4 0 5 4 7 2 7 l A 7 V Y 1 0 6 0 3 a I R 1 1 3 1 2 3 4 6 5 c U A 3 o Q U L E N A R J 7 E t 8 T A P 0 4 8 7 6 0 5 9 N R t 6 7 3 0 5 2 4 1 7 9 1 8 3 3 0 2 5 8 1 0 9 3 ( F 9 1 0 S 5 4 E 3 2 1 0 4 3 0 9 N A 2 r OM e . I _ T , t C A N n N T D e I T C , S e O 9 5 al OD E 7 9 5 6 4 3 0 9 1 4 2 4 6 6 3 2 0 1 6 4 1 9 2 2 4 7 1 t l a i D v N, - 1 0 3 3 3 4 0 2 5 3 3 3 1 4 h 7 1 4 c s i A AL L T ?2 t a , UI m . i g T A l d - C l 8 2 7 6 9 0 3 8 2 0 3 1 3 4 B _ . 7 1 8 4 7 - 2 9 5 5 4 6 3 1 2 6 6
- 1 S 2 2 1 4 'a. l 1
1 1 4 1 3 2 3 7 n a _ 3 o r _ 3 i e t d a e _ 3 N F E _ L B A H e T T N B R R Y L c N A A t
- L G P T V C A r E P A U U U E C O E u M
O H J F M A M J J A S O N D 0
)A s
u o oo scc lli'
l l The mean monthly salinity at high tide in Brown's River ranged from 26.4 i 3.2 ppt in April to 31.5 i 1.1 ppt in January during the nine-year study period (Appendix Table 3.3.1-1, Figure 3.3.1-1). High tide salinity was always higher than low tide salinity due to the influx of more saline water from Hampton Harbor into Brown's River. The influx tempered the extremes which occurred at low tide due to environmental conditions. 1 At the control station in Hampton Harbor, the mean monthly low tide salinity during the nine-year study period ranged from 24.1 i 3.8 ppt in April to 29.9 i 0.7 ppt in September (Appendix Table 3.3.1-1). The salinity in Hampton Harbor was always higher than in Brown's River (Appendix Table 3.3.1-1), due to its proximity to the inlet. Annual precipitation was inversely related to average yearly salinity during every year of the 1980-1987 study period in Haupton Harbor; when rainfall increased, salinity decreased (Figure 3.3.1-2). Brown's River generally followed the same inverse relationship with rainfall except for ) 1981 and 1984. In 1981, average yearly low tide salinity decreased by 1.00 ppt in ihmpton Harbor, but increased by 0.4 ppt in Brown's River (Table 3.3.1-1). In 1984, when average yearly low tide salinity in Hampton Harbor went up 0.3 ppt, it went down by 1.3 ppt in Brown's River. The Seabrook Station settling pond outfall usually contained fresh water from the sta-tion's sewage treatment plant and runoff from rainfall. During the years of highest discharge from November 1979 through November 1983 (Figure 3.3.1-3), the outfall became saline, containing mostly offshore sea water from tunnel dewatering, with salinities of approximately 31 ppt. In 1981, when the amount of discharge peaked, there was a slight (+0.4 ppt) increase in average yearly salinity in Brown's River when the control station showed a decrease (-1.0 ppt) (Table 3.3.1-1). In 1984, when dewatering of the tunnels was terminated and saline discharges ended, the salinity in Brown's River dropped 1.3 ppt from the previous year, while salinity in Hampton' Harbor rose 0.3 Since the salinity changes were small (+0.4 and -1.3 ppt), it is ppt. l J difficult to determine whether they are due to natural variation, or marked the beginning and end of tunnel dewatering, i I 189 _ - - - - - - _ - - - - - - - - 8
Station 3
-60 SAUNITY
** PRECIPITATION _
VJ
.- w 24 - ,.
-50 6
. z
' -. , ,........... c.
g- . p 22 - ,....' *
,,.**.. 40 g n
e .. < z .
*..' b 3
g ,***...* D. u) 20 - -30 0 m a: c. 18 , , i e i i i i 20 1980 1981 1982 1983 1984 1985 1986 1987 YEAR Station 9 30 - - 60 SAUNITY
- - .. PRECIPITATION m
E 29 - ,.***...,'. O
- 50 m o
a.
- a. *
..."" x
~
28 - ,. .
- -40 $
b 27 - ..,
, E: <
p u)
'.*,.**.. -30 26 o w
a: Q. 25 i i i e i i . . 20 1980 1981 1982 1983 1984 1985 1986 1987 I YEAR j Figure 3.3.1-2. Mean annual salinity at low tide in Brown's River (3) and in Hampton Harbor (9), and total annual l precipitation from 1980 through 1987. Seabrook i Baseline Report, 1987, 190 l
)
5-4- O < 0. l C 3 ( ' O m ' Z ) o 2- g J- U
.J 5
l 1-( outfall wth increased salinty 0 , ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,,,,,,,, ONDJFMAMJJA 80NDJFMAMJJA 80NDJFMAMJJA 80NDJFMAMJJA80ND 1978 1979 1980 1981 1982 5-4- O n. C 3-u. O . m z l' C 2-3
~
lE 1-0 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, JFMAMJJA80NDJFMAMJJASONDJFMAMJJASONDJFMAtJJA80NDJFMAMJJASOND 1983 1984 1985 1986 1987 f Figure 3.3.1-3. Monthly outfall from the Seabrook Settling Basin i from 1978-1987 in millions of gallons per day (GFD). I Seabrook Baseline Report, 1987. 191 j
I Mean monthly temperature at low tide in Brown's River ranged from 0.9 i 0.8*C in January to 21.4 1 1.0*C in July during the nine-year study . period (Appendix Table 3.3.1-1, Figure 3.3.1-1). In 1987, average monthly 1 temperatures were within the 95% confidence limits of the nine-year monthly l averages except for May which was slightly cooler in 1987 (Figure 3.3.1-1) and August, which was warmer. The mean average yearly temperature was not computed for Brown's River in 1987 because no data were collected in January or February, traditionally the coldest months of the year. In Hampton Harbor, average monthly temperatures at low tide ranged from 1.0 i 0.7'C in January to 18.6 i 1.0 C in August during the nine-year study period (Appendix Table 3.3.1-1). Hampton Harbor water at low tide was slightly warmer than Brown's River in November, December, January and colder during the rest of the year. The annual mean low tide temperature in Hampton Harbor in 1987 was 10.0'C, very close to the nine-year average of 10.1 C (Table 3.3.1-1). In both Brown's River and Hampton Harbor, the 1987 monthly temperatures were close to the nine-year average (Figure 3.3.1-1). Sediment Yearly and seasonal differences in sediment collected in 1978-1984 indicated estuarine sediments were very patchy with spatial variability often exceeding annual variability (NAI 1985b). Yearly averages at subtidal stations (3 & 9) showed grain size was fine sand, which was usuallv poorly sorted with organic carbon ranging from 0.97 to 2.08% (NAI 1985b). The i l- yearly averages for intertidal stations (3MLW and 9MLW) showed the grain size # varied from fine sand to silt, which was often very poorly sorted. The percentage of organic carbon was higher than at subtidal stations and ranged t from 1.56 to 5.86% (NAI 1985b). Although differences in low tide salinity in Brown's River appeared from 1980-1982, sediment parameters during that period i were apparently within the range of natural variation. I i t 192
p 3.3.1.~2 Macrofauna The estuarine benthic communities in Brown's River (Station 3) and Mill Creek (Station 9) were usual for quiet, tidal creeks with fine-grained sediments, where average monthly salinity ranged from 18 ppt to 25 ppt (Appendix Table 3.3.1-1). Spatial distribution of organisms was very patchy, and large population fluctuations' occurred seasonally, as is typical in estuarine habitats. Deposit and surface deposit feeders predominated, usually' composing over 70% of the fauna at Stations 3, 9 and 9MLW (NAI 1985b). Three taxa comprised the majority of individuals: Streblospio benedict 1, 011gochaeta, and Capite11a capitata. The clam worm, Nerels diversicolor, was very abundant intertidally in Brown's River (3MLW). The-soft-shelled clam, Nya arenaria, was also present in substantial numbers at all sampling locations (Table 3.3.1-3). Total abundance of organisms (number /m 2
) showed year-to-year variations that appear to be related to area-wide environmental trends. The years.of highest overall abundance were 1980-1982, when the geometric mean annual abundance reached a 10-year high of 8424/m 2 in 1981 (Table 3.3.1-3).
The period of 1980-1982 was the period of lowest precipitation, highest salinity and highest discharge flow from the settling basin into Brown's River. The years 1983 and 1984 were the years of lowest salinities, highest precipitation, and highest temperatures for the study period (Tables 3.3,1-1 and 3.3.1-2). By 1984, total abundanc.c at all four stations had declined greatly. In 1986, the total abundance (2980/m2 ) recovered and was close to the abundance in the pre-outfall period, 1978 and 1979 (3514/m and 4099/m2 , respectively; Table 3.3.1-3). -In 1987, total abundance reached all time lows j at three of the four stations (Figures 3.3.1-4, 5). Extremely low salinities in April, May and September, 1987 (Figure 3.3.1-1) may have'affected recruit-ment rate. When total abundances between corresponding subtidal and inter-tidal station pairs in Brcwn's River and Mill Creek were. tested with a paired t t-test,'no significant differences were found (Table 3.3.1-4). 1 1 193
.i.. j m.___ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ . _ . _ _ _ _ _ _' i .
'I
R 0 7 3 5 - 2 6 4 8 5 7 3 8 7 4 5 3 9 9 7 8 2 2 2 5 E 4 3 3 3 6 2 9 9 7 1 4 2 8 3 2 4 6 3 1 1 2 8 0 9 P 1 1 6 8 5 4 3 2 5 5 5 7 4 2 15 2 4 1 3 1 P 4 5 5 7 4 1 1 Z U 5 8 9 7 9 S I 1 R D I 1 A R 4 0 7 7 - 1 3 3 8 9 3 7 2 0 3 9 0 6 0 3 5 8 7 2 7 E E 3 2 2 2 9 7 0 2 0 5 5 8 3 6 8 7 7 1 9 5 1 5 0 0 MG Y N 0 9 2 2 1 1 4 3 2 1 1 1 4 2 1 1 1 R O 2 1 3 3 3 S F L L R ) L A A E 3E Y L . P M 7 3 0 1 - 0 0 1 9 1 3 0 9 3 5 5 6 8 3 9 0 3 2 5 5 L M A 3 3 3 3 5 8 7 4 7 5 4 6 2 7 1 5 8 1 8 1 2 0 7 4 L A E 9 1 2 0 7 2 1 7 7 3 3 3 2 7 3 1 2 1 1 1 A S M 2 3 4 5 3 R E ) V 9 7 O 8 8 3 1 3 6 3 8 6 7 3 5 6 9 6 1 8 3 1 5 1 7 7 3 6 9 2 9 3 2 2 1 2 9 2 2 5 9 6 4 1 1 5 3 3 1 6 5 5 1 2 1 4 OKE D 1 1 7 7 6 9 1 1 3 1 1 2 1 1 1 A E R R C 6 A 8 8 6 2 6 5 2 9 2 2 0 9 1 1 9 5 5 8 8 2 7 3 8 7 4 8 E L 9 3 3 3 3 3 8 1 3 0 6 9 6 2 9 1 9 2 6 4 3 7 0 9 3 2 Y L 1 1 8 6 3 9 1 41 12 4 5 9 7 4 8 1 2 2 I 1 2 5 4 2 HM C A O E P 4 8 7 1 8 1 2 4 0 7 1 5 9 6 5 0 2 A 9 2 2 1 2 2 5 2 2 2 8 6 8 4 3 1 R 7. 1 4 2 8 3 1 3 1 3 6 4 2 6 8 7 9 6 2 2 0 9 2 6 1 1 7 2 5 5 2 2 1 3 5 2 1 3 O ) 8 1 2 5 1 1 F 3 9 f 1
)
2 R , 3 2 6 8 3 2 mE T 8 3 3 2 3 3 5 3 3 1 4 2 8 5 5' 2 6 3 2 7 1 6 6 8 0 1 3 3 2 5 6 5 3 2 1 4 5 0 9 7 3 7 0 0 4
/. VI OR 9 1
6 5 7 2 4 2 1, 43 5 5 5 2 8 3 5 6 2 8 9 1 2 1 2 3 2 8 3 oR P 1 N E 1 I S R Y N' E 7 4 5 6 8 1 5 2 3 6 4 1 4 4 5 9 8 0 5 3 9 1 0 6 3 I N N 2 4 3 3 3 3 3 3 2 8 9 6 8 8 5 2 8 5 5 6 2 T O I 8 3 3 0 8 9 4 7 4 S R L 9 9 4 8 3, 77 0 1 5 3 9 3 2 1 0 3 5 8 2 1 8 2 5 2 4 N B E 1 1 E S 1 D T A A B N A S K E N O 2 4 8 1 1 0 7 3 9 4 5 5 8 0 2 1 9 0 1 6 M O O 1 4 4 3 4 4 6 7 3 8 2 2 2 2 0 1 3 7 4 0 8 I R 8 3 5 6 2 6 4 7 7 4 2 1 C T B 9 5 2, 8 6 1, 84 5 5 9 7 9 2 6 9 3 8 6 4 2 2 3 3 I A A 1 1 2 R T E 1 1 T E SS I E MN E I 0 G R ). 8 8 7 1 5 8 3 4 3 3 3 8 7 5 7 4 7 6 9 4 4 3 6 0 6 4 4 0 8 7 1 3 3 8 5 9 A 5 9 9 6 9 3 9 9 1 6 8 0 1 1 6 7 2 5 3 2 6 E f 8 1 4 7, 5 6 7 1 3 0 4 6 2 9 3 0 6 1 4 1 1 2 H T S 1 n9 4 2 1 2 1 2 1 E 01 G A GIN 1 9 1 4 7 5 7 6 9 6 2 9 3 6 5 4 3 0 0 6 0 3 3 9 9 5 0 A FR C 7 4 3 3 3 3 1 0 3 1 9 9 2 2 0 3 6 7 0 8 1 5 6 2 2 4 4 X I L 1 6 2 1 5 0 1 5 4 1 2 1 1 8 2 A S C 4 2 6 4 4 T T X I E F M I O I 8 5 6 8 8 9 0 9 0 0 4 7 6 9 6 4 2 6 7 4 9 L 7 7 3 2 2 2 2 7 1 6 2 1 6 0 3 6 1 1 8 7 9 0 R 8 9 1 6 2 1 5 4 1 8 7 1 1 3 1 7 6 E E 9 1 3 3 4 3 3 3 1 4 5 3 2 5 1 2 2 B C 1 MNE t H N D G I U N N F O O N N N N N N N N N N N N A N R I L L A L L A L L A N N N E O H T M M E L L A L L A M C T A M M E M M E M M E M M E T 3 9 3 9 M 3 9 3 9 M 3 9 3 9 M 3 9 3 9 M 3 9 3 9 M S 3 1 a 3 t e a 3 t c i n p E a a I. a d o a c B x n i i t A a u T T p t e a b A s c a 1 f oi h 1 o l l d c e b e o t a e n g i o. t o r e i p t b l a N T S O C I lIlll ll
- R E P 3 2 5 8 4 6 4 8 0 6 2 5 2 1 5 6 5 6 6 8 8 1 0 5 0 6 1 6 2 4 P 1 0 2 1 1 2 1 2 1 1 1 U 1 S R A R E E 0 2 1 2 2 6 1 4 0 7 4 9 5 7 0 YW 7 1 8 6 8 1 3 3 2 4 9 3 5 7 O 3 L L L A - N A 7 2 5 4 6 8 7 2 0 2 9 7 1 6 9 E 0 2 4 1 1 1 2 7 9 4 6 5 6 9 8 - M 1 6 1 1 1 7 8 3 2 0 6 8 1 3 7 1 5 0 3 7 3 2 9 4 5 1 8 3 5 2 7 4 1 1 6 8 2 3 7 4 3 9 0 5 7 3 1 4 3 3 9 9 5 4 8 8 4 1 5 0 5 2 3 1 1 1 1 9 1 1 2 3 4 8 0 7 6 3 9 2 7 4 5 4 1 7 2 6 5 9 5 9 1 8 1 4 2 3 3 5 2 8 5 1 2 5 3 1 3 5 7 0 7 5 3 5 2 8 7 5 8 3 0 8 8 4 2 5 4 3 5 7 3 7 6 0 7 9 9 2 2 1 1 1 2 1 5 5 3 2 6 3 4 4 2 8 7 1 4 2 5 4 7 3 2 3 2 3 6 3 4 1 4 3 8 4 9 1 2 1 6 1 1 1 1 1 9 1 1 2 5 3 1 0 1 2 3 3 7 1 6 9 0 7 1 5 0 1 4 1 9 4' 1 8 4 7 0 3 8 3 2 6 12 4 2 1 2 1 4 2 9 1 0 8 1 9 1 7 5 6 7 8 3 2 9 6 2 2 8 5 4 6 0 6 3 4 0 4 8 9 9 2 6 8 9 1 1 1 1 8 6 1 2 1 1 9 2 9 3 4 3 1 0 4 8 7 8 7 4 8 5 e 7 7 2 4 6 8 2 4 7 9 + 5 2 2 2 6 t 9 1 3 1 1 2 1 2 1 1 4 2 3 2 a 1 1 c i l p e 8 7 3 1 0 0 5 0 0 6 8 2 9 5 6 0 8 r s 8 2 0 7 2 3 1 0 4 6 6 0 0 1 s n 9 8 1 1 3 1 2 1 1 1 r e a 1 e t e p a c m sr s r i y a n e l lr ey N a b p
)
d O I N H N L L A H H N L L A W N N L L A e s mn m u r e a e 9 e T M M E M M E M M E o n v u A 3 9 3 9 M 3 9 3 9 M 3 9 3 9 M i s 3 I n T s a l i S n e a = t n os s t o n o r a3 t a C o B e I e ( l s m o . I = c p
. i S = n 's 3 s a r - r a a n e a 1 e l i a m e v l r e y 3 i e a m l d n 3
i a l s r e y n l e r l o a E i 1 a r s r . L e 1 a a e B r u A T N e C a g Y e S e O v _ M a - Wetn
4 Subtidal Subtidal 5-
- 80 -
< Station 3 .
Station 3 - u . 70 -
? -
4 . 4 ' .. M 4 60 - 4-
- i
- / u. 50 -
/ O
/ ""
z 3-g 40 - e
/g \
w ' 3 30 - "
\
Q " ' g 20 - , a . 2 . . . . . . . . . 10 . . . .... . 1978 1979 1980 1981 1982 1983 1984 1988 1987 1978 1979 1980 1981 1982 1983 1984 1988 1987 YEAR YEAR Subtidal Subtidal 6 - Station 9 80 Station 9 y 5- . 70 - n xa 60 - a - d N/^N 4- .. N 50 -
. _ u. .
.. s g ..
O 4o - in 3 - - ' (C
\"' ,
2 - " g 30 - " g .
" ,s 20 -
e 2- z .. O, 10 - 1 . . . . . . . . 0 i 1978 1979 1980 1981 1982 1983 1984 1988 1987 1978 1979 1980 1981 1982 1983 1984 1988 1987 YEAR YEAR i i Figure 3.3.1-4. Yearly mean and 95% confidence limits for the log (x+1) density of macrofauna and number of taxa collected ! at subtidal estuarine stations sampled three times per i year from 1978 through 1987 (excluding 1985). ~ Seabrook l Baseline Report, 1987. ' 196
1 f l l i
'"' "" I 70 - Intertidal g5 Station 3MLW M -
60 - Station 3MLW f d p - L ,
.. 5 50 - ,, i d 4- -
>= -
" j
< f
- u. 40 -
4 l
.g m
30 - h s 2 3- E l w.
.. lE 20 - .
I Q 3 ' i . - Z 10 - - t. 82 , , , , , , , , , 0 , , , , , , , , , 1978 1979 1980 1981 1982 1983 1984 1986 1987 1978 1979 1980 1981 1982 1983 1984 1986 1987 YEAR YEAR i i intertidal g 6 Station 9MLW Intertidal ! 7 E 5- .. Station 9MLW ' F- - 60 - "
- E g 50 -
3- - " - g40 yg ..
~
$ 2- g 30 - ,
'$ $ 20 -
3 m -
@1-Z 10 - . .
a 0 , , , , , , , , , o', , , , , , , , ,--- 1978 1979 1980 1981 1982 1983 1984 1986 1987 1978 1979 1980 1981 1982 1983 1984 1986 1987 YEAR YEAR l l Figure 3.3.1-5. Yearly mean and 95% confidence limits for the log (x+1) density of macrof auna and number of taxa collected at intertidal estuarine stations sampled three times year from 1978 through 1987 (excluding 1985). Seabrook Baseline Report, 1987. 1 197 Illii'I
.. f i
TABLE 3.3.1-4. RESULTS OF A PAIRED t-TEST FOR SELECTED BIOLOGICAL VARIABLES FROM PAIRED SUBTIDAL (STA.3-STA.9) AND INTERTIDAL (STA.3MLW-STA.9MLW) STATIONS SAMPLED THREE TIMES PER YEAR DURING 1978-1987 (EXCLUDING. l 1985). SEABROOK BASELINE REPORT, 1987. 2 STATION DEGREES OF VARIABLE PAIR FREEDOM t-VALUE* PR>ltl
.(
Number of Taxa Subtidal 26 2.12* 0.0441 k Intertidal 26 -0.96 0.3450 Total Abundance Subtidal 26 -0.41 0.6816 Intertidal 26 -0.77 0.4491 Stroblosplo benedicti Subtidal 26 1.31 0.2010 Intertidal 26 0.15 0.8837 Capite11a capitata Subtidal 26 -1.76 0.0906 Intertidal 26 -1.60 0.1215 Nerfs diversicolor Subtidal 26 5.59*** 0.0001 Intertidal 26 5.59*** 0.0001 Cau11erle11a sp. " Subtidal 26 -0.51 0.6129 Intertidal 26 -0.37 0.7169 Nya arenarla Subtidal 26 -3.52** 0.0016 Intertidal 26 -2.12* 0.0442 011gochaeta Subtidal 26 0.33 0.7406 Intertidal 26 -2.62* 0.0144
*The t-value was computed for the difference between the log (X+1) of the abundance (No./m") taken seasonally (May,. August, November) for nine years for a station pair for the important species and the total abundance of all non-colonial macroinvertebrates in a sample. Number of taxa is the mean for a season, and was not transformed. Negative t-values indicate that the station near the settling basin discharge (3 or 3MLW) had a lower mean value than the control station (Sta. 9 or 9MLW).
* = significant differences at alpha = 0.05
** = highly significant differences at alpha = 0.01
*** = very highly significant differences at alpha = 0.001 l
198 Y___ ____ -
The seasonal cycle of total abundance showed density was usually highest in May or August at both intertidal and subtidal stations (NAI 1987b: Figure 3.3.1-4). The usual increase in abundance in spring or summer was probably due to the recruitment of one or more dominant taxa (NAI 1985b). The 1984 densities had no major seasonal peak at any of the four stations. 4 It was also the second consecutive year of very high precipitation (Table 3.3.1-2) and very low salinities (Figure 3.3.1-2). The low densities observei in Brown's River and Mill Creek in 1984 may have been related to spawning and recruitment failures in 1983 and 1984, caused by more extreme natural conditions. Similarly, rainfall in April, 1987 was at a 10-year high, and was also very high in September, and total abundance was at or near an all time low for each of the four stations (Table 3.3.1-3). The mean number of taxa collected annually at all stations combined ranged from 22 taxa in 1984 to 41 in 1981 (Table 3.3.1-3), and significant differences were found among both years and stations (NAI 1987b: Tabic 3.3.1-4). The years 1980 through 1982 had the highest number of taxa collected, while 1984 and 1987 had the lowest number of taxa (Table 3.3.1-3, Figures 3.3.1-4, 5). The seasonal cycle at each of the four stations showed that the highest number of taxa usually occurred in August or May, and the lowest number occurred in November (NAI 1987b: Figure 3.3.1-5). The two subtidal stations had a higher number of taxa averaged over all years than the two intertidal stations. When a paired t-test was done between subtidal stations in Brown's River and Mill Creek, Brown's River was found to have a significantly higher number of taxa than Mill Creek. However, the intertidal stations were not significantly different (Table 3.3.1-4). The annual trend in the number af taxa seems to show a relationship with the mean annual salinity. When annual salinity dipped below 20 ppt, the number of taxa declined. Previous years (1983, 1984) showed decreases in numbers of taxa at most stations coincident with high spring rainfall and low salinity (NAI 1987b; Tables 3.3.1-1, 2), and a similar pattern was noted in 1987. l 199
SUBTIDAL STATION 3 Nerels , Mya 4 >. 3- 3-b - . b m - . 7 / m . 2- "/1 . h 2- b/ N .. - 8 - e o .
\ -
"3 a 3 0- . . . . . . . . . 0 . . . . . . . . 1978 1979 1980 1981 1982 1983 1984 1986 1987 1978 1979 1980 1981 1982 1983 1984 1986 1987 YEAR YEAR SUBTIDAL STATION 9 4 Nerels Mya 3- 4- - D & m m a 2- " e - - " e 2- - O o s 1- - - d 0 . . . . . . 0 ... 1978 1979 1980 1981 1982 1983 1984 1986 1987 1978 1979 1980 1981 1982 1983 1984 1986 1987 YEAR YEAR i Figure 3.3.1-6. Yearly mean and 95% confidence limits for the log (x+1) ; density of Herels diversicolor and Hya arenarla collected at subtidal estuarine stations three times per year from 1978 through 1987 (excluding 1985). Seabrook Baseline Report, 1987. - 200
Stroblosplo benedictl is an opportunistic polychaete (Grassle and Grassle 1974), and one of the first to colonize after a perturbation of the environment (Rhoads et al. 1978). It is the most abundant species in the estuary, exhibiting significant differences in abundance among both years and stations when tested with a two-way ANOVA (NAI 1987b: Table 3.3.1-4). All-time high geometric mean densities were reached in 1981 and 1982, during the period of high salinity and settling pond discharge (Table 3.3.1-3). In 1987 the population decreased dramatically to an overall density of only 58/m 2 . When stations were compared, the two intertidal stations had the highest densities, and the two subtidal stations had the lowest densities. No significant differences were found between station pairs in Brown's River or Mill Creek (Table 3.3.1-4). The seasonal cycle of S. benedleti indicated that extremely high densities occurred during any season at both intertidal and subtidal stations. Such high densities were rarely sustained into the next sampling period, causing tremendous population fluctuations (NAI 1987b: Figures 3.3.1-6,7). The class 011gochaeta was very abundant in the estuary. Compari-sons among years showed the years of highest abundance were 1980-1983 when geometric mean population densities ranged from 646/m 2 in 1981 to 931/m 2 in 1983 (Table 3.3.1-3). The years of lowest abundance included 1978 and 1987 when density (averag;ed over stations) was 119/m 2 and 157/m2
, respectively.
Thus, the years before and after the period of highest salinity and discharge had similarly low densities. Interstation comparisons showed the stations with the highest overall abundance were Station 9MLW and 9 and stations with the lowest abundance were Stations 3 and 3MLW (Table 3.3.1-3), but these differences are too slight to be significant with a paired t-test (Table 3.3.1-4). The seasonal cycle of oligochaetes indicated that peak densities occurred during any season (NAI 1987b: Figures 3.3.1-6,7), but were not sustained. The opportunistic polychaete Capite11a capitata was abundant in the estuary at both intertidal and subtidal stations, but had lower population densities than S. benedicti and 011gochaeta. The highest population den-sities averaged for all stations occurred from 1980-1983, when overall 201
INTERTIDAL STATION 3MLW ' Nereis Mya 5- , 4- . 4- " 3-
, g
! , h -
..\ 2-N - "
8 a 8 / a ,_ 1- , . 0 . . . . .. . o . . . . . . . '.' 1978 1979 1980 1981 1982 1983 1984 1988 1987 1978 1979 1980 1981 1982 1983 1984 1988 1987 YEAR YEAR INTERTIDAL STATION 9MLW Nereis Mya. 4- .. 4 .. 3- ' 3- .. t 2- \ ' 2-N - I 1- , a ' 3 ,
.. 1 0 . . . . . i ' '
O , . . . . . i 1978 1979 1980 1981 1982 1983 1984 1988 1987 1978 1979 1980 1981 1982 1983 1984 1968 1987 j YEAR ' YEAR i i 1 Figure 3.3.1-7. Yearly mean and 95% confidence limits for the log (x+1) density of Herels diversicolor and Hya arenaria k collected at intertidal stations three times per year d from 1978 through 1987 (excluding 1985). Seabrook Baseline Report, 1987. 202
geometric mean densities were between 269-443/m (Table 3.3.1-3). The years ) of lowest abundance were 1978, 1979, 1984, and 1987 when abundance was less than 100/m (Table 3.3.1-3). No significant differences were found between station pairs in Brown's River or Mill Creek using a paired t-test (Table 3.3.1-4), but densities were usually higher in Hill Creek (Table 3.3.1-3). ] 1 Cau11erle11a sp. B is a polychete that was occasionally abundant in } the estuary. Its annual geometric mean density at all stations ranged from 5/m in 1987 to 183/m2 in 1980 (Table 3.3.1-3). 8 It rarely sustained densi- ; ties of over 100 for more than three consecutive years, and in 1987 it had i annual densities of less than 10 at three of the four estuarine stations (Table 3.3.1-3). No significant differences were found between Brown's River ; and Mill Creek (Table 3.3.1-4). The clam worm, Nerels diversicolor, is a highly euryhaline species which can easily adapt to salinities ranging from 1-25 ppt. It is common 1 where there is a mixture of fresh and salt water, and can penetrate up the l 1 estuary further than most " marine" worms (Pettibone 1963). It builds a fairly permanent U-shaped burrow, and unlike many nereids, fertilization and development occur in the burrow without a planktonic larval stage. It lives l for about 18 months, and has one breeding season, Spawning occurs in late winter or early spring with a marked temperature change, and afterwards the females die. By the end of the first summer, juveniles are 10-20 mm in length. Adults may reach up to 200 mm in length (Pettibone 1963). The geometric mean population densities at each of the four stations were usually highest from 1981-1982, and reached an all time low in 1987 (Table 3.3.1-3, Figures 3.3.1-6, 7). Both intertidal and subtidal stations at Brown's River had significantly higher densities than stations of comparable depth at Mill Creek (Table 3.3.1-4). Intertidal stations had higher densities than sub-tidal stations (Table 3.3.1-2), as expected, since the species is primarily intertidal (Pettibone 1963). 203
Nya arenarla, the soft-shelled clam, is a euryhaline species that tolerates rapidly changing salinities, and can survive in sustained salini-ties as low as 4 ppt (Green 1969). In Hampton Harbor, the green crab, Carcinus maenas is an important predator of Nya, and its abundance may affect the success of recently-settled young (Section 3.3.7). Recently-settled Nya were present at all estuarine stations, and overall densities were highest in 1979 and 1981 (265/m and 237/m s
, respectively), and lowest in 1986 and 1987 (19/m and 42/m , respectively) (Table 3.3.1-3).
8 8 Significant differences were found among years and stations (NAI 1987b: Table 3.3.1-4) with the earlier years generally having higher densities, and Mill Creek having higher densities than Brown's River. Likewise when intertidal and subtidal station pairs in Brown's Rivet and Mill Creek were tested with a paired t-test, densities in Mill Creek v9re found to be significantly higher (Table 3.3.1-4). Population densities in 1986 reached an all-time ~ low at all four stations (Figure 3.3.1-6 and 7) and green crab densities in Hampton Harbor were very high (Figure 3.3.7-9). However, in 1984, when green crab densities reached a 10-year high, clam densities were about average. In summary, changes throughout the estuary occurred in total abundance, number of taxa, and abundance of the most dominant species. As these changes were not site-specific, and occurred at Brown's River and Mill Creek at the same time (except in 1983), they were probably related to area-wide environmental variables such as precipitation and corresponding salinity changes, temperature, and abundance of predators and competitors. { The period of high salinity and high settling pond discharge (1980-1983) showed population increases for most of the estuarine worms, total abundance, j and number of taxa. Increases in the settling basin discharge volume probably acted in conjunction with low precipitation to increase salinity in Brown's River slightly. By 1986, physical and biological parameters had returned to the pre-1980 conditions, but in 1987 abundances for five of the ; six dominant taxa were at or near all-time lows in both Brown's River and l Mill Creek. At the same time salinities reached a 10 year low during three I months in 1987, due to heavy rainfall. )
'l 204
\ 3.3.2 Marine Macroalgae 1 3.3.2.1 Macroalgal Community Species Collections 1 From 1978 to 1987, 123 species of macroalgae were recorded from general species collections at 12 benthic stations (Appendix Table 3.3.2-1). l ) As is typical of this region, 52% of these taxa were red algae (Rhodophyta), j 25% were brown algae, and 23% were green algae (Mathieson et al. 1981a,b). Four of these species were collected only in 1985 and 1986: Bevaloraea ramentaceum and Phyllophora traillil, which are red algae; and Petalonia zosterifolla and Sorapion kjellmanfl, both brown algae. D. ramentaccum and S. kjellmanil were collected only from tide pools. All four species have been previously collected from the nearshore open coast between Portsmouth and Seabrook, New llampshire by Mathieson and IIchre (1986). Only one new species, Polysiphonia denudata, was recorded in 1987. This species, which
]
was found only once (Station.5MLW), is an estuarine species and was likely a drif t specimen from llampton Harbor. Spatially, the highest number of taxa collected throughout the historical period were in the mean low water (MLW) zone (a median of 57 at Station SMLW); numbers decreased with increasing depth, with the fewest species collected at the deepest stations (Figure 3.3.2-1). Number of species collected also decreased with increasing eleva-tion from MLW (e.g., at the MSL stations). For the most part, the numbers of taxa collected at nearfield and farfield stations from 1978 to 1987 were similar. Exceptions were the MLW zone where more taxa were recorded at Rye Ledge (5MLW) than at the Outer Sunk Rocks (1MLW) and the mid-depth zone where fewer taxa were recorded at the station near the intake (Station 16) than at the farfield station (Station 31). Numbers of taxa collected in 1987 were within the range collected over the prior baseline period (1978-1985), with few exceptions. 'No additional taxa were recorded at Stations 17 and 31 in 1987; however, these were not species new or unusual in the study area as a whole. 205
l a n MEDIAN
.. RANGE 62 - .. b NUM8ER OF SPECIES 60 - D-1985 m -1987 58 - 0-1986 3
56 - c NF = NEARFIELD 54 - o FF = FARFIELD
~~" '"
50 - V d SEE APPENDIX TABLE 3.3.2-1 A FOR PERIODS OF COLLECTION 48 - AT EACH STATION 46 - b O , 44 ~ 42 - -- 40 - A -- 38 - ga h 36 - g 34 - MLW -- O g 32 - g 30 -
- u. 28 -
26 - @ , E 24 - n f l 22 -
~~
O H z 20 - " o 18 - " 16 - A o N 14 - ,, g A 12 - g3L - -- 10 - 8- - 6- MSL 4-2- 0 , , , , , , , , , , 1 5 17 35 16 19 31 13 a 3a NF' FF NF FF NF NF FF NF NF FF INTERTIDAL SHALLOW MID-DEPTH DEEP 1 j Figure 3.3.2-1. Number of macroalgae species in general collections at each marine benthic station'for 1978-1984 (median and { range) and 1985-1987 (number collected each year). .l Seabrook Bar sline Report, 1987. } 206 j
l !
)
In several cases the number of taxa in 1987 general collections ] represented the highest (Stations 17,16,31,4) or near-highest (Stations i 35 and 19) number collected during the baseline period. However, not all ) I stations were sampled for the entire 1978-1987 period.(See Appendix Table i 3.3.2-1). Only at Station 1MLW were numbers of taxa collected low in 1987, in fact they were the lowest on record. Low numbers of taxa and abundances l were observed at several stations in 1987 for macrofauna in the benthic 1 destructive collections (Section 3.3.3). Annual Biomass Collections The effect of depth on light quality and quantity is reflected in the biomass of macroalgae and the number of taxa collected at the hard substrate (algal-covered rock and ledge) stations sampled from 1978 through 1987 (Figure 3.3.2-2). The numbers of taxa recorded were greatest at the intertidal (MLW) sites, declined to 20-25 taxa as depth increased to about 9.5 m, then declined to approximately 15 as depth increased to 20 m. Biomass values were similar at the intertidal and shallow subtidal stations, then declined until depth reached 18-20 m. Numbers of taxa and biomass values I were generally similar between nearfield and farfield stations. However, mean biomass at Farfield Station 31 (Rye Ledge) was 46% greater than the Nearfield Station 19 (Discharge) and 42% less than Nearfield Station 16 l (Intake). More taxa were recorded in the biomass samples from the farfield intertidal site (SMLW) than from the nearfield station (1MLW). A temporal presentation of annual August biomass levels (Figure 3.3.2-3) at the nearfield stations indicated no consistency among year trends. At the intertidal Sunk Rocks site (1MLW), mean biomass was lower during the 1978-1981 period than during the 1982-1986 period; the 1987 mean was more similar to the earlier period. At the shallow subtidal (17), mid-depth (19) and deep (4) stations there was some variability among years but it was relatively minor and there were no among year trends evident. 207
60 50 h MLW 40 4.6 m Depth (m) below MLW 4.6 m 9.5 m 9.6 m 20 18.3 m 19.7 m 19.7 m 10 0 1MLW SMLW 17 35 16 31 19 13 4 34 STATION i 1500 4.6 m p 4.6 m Depth (m) below MLW { 1000 9.6 m h 500 9.5 m 13.7 m 19.7 m 10.7 m 0 1MLW SMLW 17 35 16 31 518.3mW19 13 4 34
'1
~
STATION i Figure 3.3.2-2. A. Number of taxa and B. mean biomass at intertidal and subtidal benthic stations in August. (See Appendix i Table 3.3.2-1 for years each station was sampled) Seabrook Baseline Report, 1987, 208
i 1 2500 - l 2500 STATION 17 1 STATION 1 MLW } " 2000 2000 - h
~ "
~ -
I m e 7 m 1500 - l m 1500 - ..
< g .. -j -
a N , 9 :w -, , h1000- .. .. .
,b' ,
soo - - 500 - i o , , , , o . . . . . . . i i . 1978 1979 1980 1981 1982 1983 1984 1985 1988 1987 1978 1979 1980 1981 1982 1983 1984 1985 1988 1987 l YEAR YEAR I I 1 i 1000 - 500 - STATION 4 . STATION 19 NS = NOT SAMPLED j g. 750 - 1 y300- $ - g ( 2-0 200 - - 9 i iii . m . V '
/*Yg "
g, 2= - o . . . . . . . . . . , , , , , , , , , , 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1978 1979 1980 1981 1982 1983 1984 1985 1988 1987 l l YEAR YEAR Figure 3.3.2-3. Mean biomass (gms/m 2
) and 95% confidence limits for !
macroalgae collected in August at selected nearfield benthic stations (note differences in scale). Seabrook Baseline Report, 1987. 209
The number of taxa collected at each station in 1987 (NA1 1988) did not excned the number collected during the baseline period (NAI 1987b) with one exception. One more species was collected at Station 19 in biomass sampics than had previously been collected at that station; however, there l were no taxa new to the study' area. The depth differences among benthic stations were also reflected in the relative abundance (biomass) of the six taxa that ware dominant during the baseline period (Figure 3.3.2-4). Pellota serrata was dominant.at the deepest stations, Phy11ophora spp. (P. truncata and P. pseudoceranoides) were most abundant at mid-depth stations, and Chondrus crispus was dominant in the shallow subtidal and intertidal. Relative abundances for 1987 showed this same pattern (Table 3.3.2-1). However, C crispus made up a higher than average percentage of biomass in 1987 at Stations 1MLW, 35 and 16 with' concomitantly lower percentages of Nastocarpus stellatus (Station 1MLW only), Phy11ophora spp. and Phycodrys rubens (Stations 35 and 16 only), respec-tively. The three other taxa listed in Table 3.3.2-1 were frequent sub-dominants. These six dominants combined typically represented more than 90% of the biomass at each station. The greatest exception to this occurred'in 1987, when "other" taxa comprised between 10 and 25% of the biomass at seven of the 10 stations sampled. This was primarily due to the abundance of red algal epiphytes which were higher in 1987 (NAI 1988a). 1 Community Analysis Station differences in the macroalgae community were caused by the depth-related differences in species' relative abundance. Historically, six depth-related station groups had been identified from cluster analysis of i August (1978-1984) samples (NAI 1985b; Table 3.3.2-2). Although several taxa had been found across all depths, each species had a depth zone within which j it reached peak biomass (Figure 3.3.2-5); it was the unique association of species' biomasses that resulted in a different community structure in each depth zone. Within each depth zone, the paired nearfield and farfield ) stations were most similar to each other (Table 3.3.2-2). 210
i 100 AWA sss s s ssssss s%sss A '< A 's 'AWs s' A W AWA 'AWs /AW s's's's's's 's'vs'es vs's's's l sW'A's '/A'A AWJ l A's <A 'vA'A AWV AWA AWA '/AA
'/A A A'/A' A W/A AWA W/A A'<w' vn VAW W/A
'v4'A
'JA'A 80
,',[ [
W/[A
'/A'A A((W/
[
#AW(( '(([
's W A[;
W/6 E Ptilota serrata
'AWs A'/A' 's W A
'AWs A'/A' W/A
'/A'A /AW' 'sWA O Phyliophoraspp.
'/A'A A'/A '/A'A W s' A AW/ 'sWA
- '/A'A AW/ W/A a.t.
W/A ejjne, A,W / '/A'A
,ge/A O corailina offic.inak.s
.. 3 AW,egj w 60 'AWs J '/A'A o 's W A A'/A' 's W A z 's W A
///
A'/A'
/////
's W A
////$
< ,s s,s,s,s s,s,s,s,s, ,s ,s,s,s,' G Phycodrys rubens Q
s's'i's's s's'o's'<
's'i i i s
's's'i i i Ni < i' s's's's',s,
$, sssss s,s,s,s,s, ,s,s,s, ,
" ', ,' E Chondrus crispus l w i i s'i s'
> s'i 's's's' 1
lYl'l E 40 W/A E Mastocarpus stellatus w W/A a: W/A
'/A'A
/////
-lylQl E OtherTaxa
'sWA
'#A'A
'AWs hhhh h hhh 20 :s:#3 :gg:g
#6W
/////
0 MLW 4.6 9.6 11.6 18.3 19.7 MEAN DEPTH (m) Figure 3.3.2-4. Relative abundance (% biomass) of dominant macroalgae at marine benthic stations (by station-depth group) in August, 1978-1987. Seabrook Baseline Report, 1987. 211
Y - $ $ $$ $ $. R$ n-% b; **9 a , -: **- : 1-- 1- -: Y1 g *"* 1 l N
. ~ $42 *$" 668 ??* **Q i
b h ( Q e e e e e tun -- --- -~- t e .e eee t= g - ,,, ,,, ,,, -~- --- ,,, ggg m-u ao- aoa uum yay umu
~
Hl W i . 2 i** i "? i** IR"
,~
i~* i*2 N: gg w g
... -.. .s .~~ ..- - . . .
g a g99 agg ... . aaa agg a s .: aaa l ,0 m f-i . ,, ,,, ,,, ,,, ,,, ,,, g - ... .~. ... uu ayn --- ..- l
. e e >
e e i* iS
- C I !"$' l8$ l* l' ~ $
* . ,~ ,, -: , 4, g,l x i- i I- i-- ixe is: i.=
13 -- ,, ,, ,, 4, -- g
. i, i n i- i- in n, i-= ;
05 g- g- gg- gys ggs gg- m,- 7
-- - -. - -- h-n r
. . 1
% 5 d.
" 3 A -
- t 1 4 # ..
- I g & C % 2 t-o :=
t .
=
e e E i t
= o a 2 :
m . 2 & . g .c e. E :
- [ & J $ 4
. 1 = a o
- i. e . <
6 8 2 2 & t E G . 212 i _ _ _ _ - - _ 1
TABLE 3. 3. 2-2.
SUMMARY
OF SPATIAL ASSOCIATIONS IDENTIFIED FROM NUMERICAL CLASSIFICATION (1978-1984) AND VERIFIED WITH DISCRIMINATE ANALYSIS (1978-1987) 0F BENTHIC MACR 0 ALGAE SAMPLES COLLECTED IN AUGUST. SEABROOK BASELINE REPORT, 1987. a SAMPLE SIMILARITY MEAN MEAN BETWEEN BIOMASS GROUP STA- DEPTH WITHIN STA- GP.0UP b NO. TIONS (m) STATION TIONS DOMIlJANT TAXA (gj,2) 1 13 18.3 .68 - Phy11ophora spp. 63.19 Ptllota,sorrata 12.09 Phycodrys rubens 5.50 Polysiphcas urcoolate 3.50 Scagella corallina 3.32 2 4 19.7 .84 .70 Ptilota serrate 65.09 34 .71 Phy11ophora spp. 8.96 Corallina officinalis 7.75 Scagella corallina 1.15 Phycodrys rubens 1.04 3 19 11.6 .78 .70 Phy11ophora spp. 196.50 31 .80 Corallina 16 officinalis 56.53 (1984) Chondus crispus 53.45 Phycodrys rubens 40.45 Callophyllis cristata 12.86 Ptllota serrata 12.61 4 16 9.4 .87 - Phy11ophora spp. 428.07 Phycodrys rubens 217.92 Cystoclonium purpureum 60.17 Chondrus crispus 53.26 Ceramium rubrum 36.99 Callophyllis cristata 34.74 continued 213
l l l TABLE 3. 3. 2-2. (Continued) l a SAMPLE SIMILARITY MEAN BETWEEN BIOMASS GROUP STA- DEPTH WITHIN STA- GROUP b NO. TIONS (m) STATION TIONS DOMINANT TAXA (g/m 2 ) 5 17 4.6 .78 .78 Chondrus crispus 767.68 35 .78 Phyllophora sp. 204.36 Ceramium rubrum 66.17 l Corallina 1 officinalls 52.63 Cystoclonium l purpureum 28.54 6 11.'LW MIM .65 .68 Chondrus crispus 969.33 SMLW MLW .65 Gigartina stellata 234.51 Corallina officinalis 47.64 Ceranium rubrum 2.62 , Porphyra l 1eucosticta 0.98
" Bray-Curtis similarity, 1978-1984 (NAI 1985b) 1978-1987 period (See Appendix Table 3.3.2-1 for stations / years sampled).
214
GROUP: II I I!! IV V VI 13 19/31 16 17/33 1/3?tLW
$PECIE5 STATIONS:b a/34 16.3m 11.om 9.4m e.6m DEPTH: l 9. 7 m MIN c
Rhodophyllis dichotoso 6 k ilots serrats Scage))s coraillas Polysiphon2s urceelate Antithoenionells floccess * ~
~
Corelline officinalis neacronopcore slots - Cyanogongrus crenulatus Collophyllis cristats Phyllophoto spp. Phycodrys rubens
- Cystoclonium purpureue Coronium rubrun Chaetomorphs melagonlue Chaetomorphs picqustaans ~
Desacrestas seuleets Collitheenion tetragonue Polvides rotundus Chondrus crispus - Chascomorphs sp. Ahnfeltis plicats Rhodomels confervo2 des Ulve lectues Mestocarpus stellatus ~ Pelaarja pelaste Polysiphonis flexicaults Porphyrs leucost2 cts Rhizoclonium cartuosus Polysiphonis lanoss Ulvsels obscurs Leschesto differals tlsch2sts fucicals Ectocarpus fasciculatus Clodopnors serscoe
" Race caxa (less than 3 occurrences tn *93 samples) no: included in this analysis Depth below ?tLW
' Peak biomass Range of occurrence l
a Figure 3.3.2-5. Occurrence and peak biomass of the common and abundant macroalgae species over the range of benthic stations sampled in August,1978-1984 Seabrook Baseline Report,1986. 215
A discriminant analysis was used as a comparative method to confirm results of the cluster analysis and to allow a comparison of 1985, 1986 and ! 1987.results with the previous baseline period. Replicates were averaged in this analysis to avoid the influence of small-scale spatial variability and to be consistent with cluster analysis methods (NAI 1985b) and the macrofauna analysis (Section 3.3.3). Species assemblages identified by discriminant analysis were identical to those identified for the baseline period by cluster analysis. Samples collected from 1985-1987 were placed in the same group as the majority of samples from previous years, verifying the similarity in species composition (Table 3.3.2-3). Therefore, although there may be differences in the biomass of a species from sample to sample or year to year within a station group, the relationship among species biomass has been very consis-tent. The degree of differences at the species level is examined for two dominant macroalgae species in the " selected species" section which follows. In order to monitor the algal community for new or infrequently occurring species which might bloom to " nuisance" levels, the rarer species occurrences were also examined. Twenty taxa occurred sparsely (less than 5% mof the biomass collections) from 1978 to 1987 (Appendix Table 3.3.2-2). The only unusual occurrence reported to date was Bonnemaisonia hamlfera which was new to biomass collections in 1986 (Stations SMLW, 31 and 35), and occurred in greater than 5% of the samples. This warmer water species has been l recorded in Great Bay (Mathieson and Hehre 1986), but not at offshore sites in tS'is study prior to 1986. The recent occurrence may have been related to the increased water temperatures in the nearshore area in 1985 and 1986 (see Section 3.1.1). More of the " sparsely occurring" taxa have also been recorded in recent years (NAI 1985b) and may be related to the same cause. Water temperatures in 1987 were lower than 1985 and 1986; in fact, the bottom i temperatures (at the Intakes) averaged the second lowest over the 1978-1987 period. B. hamlfera was not recorded at any stations in 1987 (NAI 19888). ,
\
i 216
I I TABL1; 3.3.2-3. PROBABILITY OF 1978-1987 MACR 0 ALGAE SAMPLE MEMBERSHIP IN EACH STATION GROUP IDENTIFIED FROM NUMERICAL i CLASSIFICATION (cluster analysis) 0F 1978-1987 AUGUST BENTHIC DATA. SEABROOK BASELINE REPORT, 1987. j l i DISCRIMINANT FUNCTION GROUP CLUSTER ANALYSIS GROUP" 1 2 3 4 5 6 l b 1 100 0 0 0 0 0 (9) I 2 0 100 0 0 0 0 (17) 3 0 0 100 0 0 0 (21) 4 0 0 0 100 0 0 (6) 5 0 0 0 0 100 0 l (16) l 6 0 0 0 0 0 100 (16) a b See Table 3.3.2-2 100 = sample percent probability of group membership (9) = number of samples per group 217
Kelp Transect Survey Spatial differences in kelp species abundance appear primarily I attributable to depth differences. Laminarla saccharina has historically bsen most abundant at the shallower stations (Figure 3.3.2-6). Laminarla digitata has been shown to reach maximum abundance in the study area at Station 31 (9.4 m below MLW), whereas Agarum cribrosum's greatest abundance was at Station 19 (13.7 m below MLW)(NAI 1985b). Significant spatial dif-ferences between nearfield and farfield mid-depth stations (Stations 19 and 31), were found for some species, where L. digitata and A1arla esculenta were more abundant at Farfield Station 31 (NAI 1985b). Abundances recorded in 1987 followed similar spatial patterns to 1978-1984 occurrences (NAI 1988), but densities of L. saccharina were higher than past years in the shallow subtidal (17, 35) while densities of L. digitata were higher at the mid-depth stations (19 and 31). No consistent seasonal variation in abundance was observed for any species of kelp, probably because " juvenile" (<15 cm) plants were not enumerated; these plants are difficult to accurately count in situ because of their small size and high density (NAI 1984a, 1985b). Seasonal variation in biomass was reflected in r,rowth studies conducted prior to 1985; growth closely followed the solar irradiance and nutrient cycles (NAI 1985b). Stand density, which is controlled by sub trate availability, recruitment and environmental conditions (e.g. storm disruption), showed some variability among years. Kelps, particularly Laminarla species, are quick-growing, opportunistic plants. Consequently, they are among the "ploneer" species that colonize freshly exposed substrate, adding to the year-to year vari-ability in distribution. Measurements of percent frequency of occurrence of the three understory algae that were dominant at transect sites (Figure 3.3.2-6), i showed differences among depths that were similar to those observed from biomass collections (Figure 3,3.2-3). Chondrus crispus occurred more q frequently in the shallow subtidal zone whereas Phy11ophora sp. and 218 1
A. Kelps Shallow Mid-depth a 3- E a neew(1s> y, {2 , O farfield(31) I , T l w2- . w2-l e E r*M*kl(17) E _T g O few(as) g m m E j. E 1-E E
$ E l
I I o. h E _ o. -
- E * *
.I *2 AS
- .E zm E= Z2
- EE:
22 E e =: e ia &2 i:s 55 ja &2 E3 {t
<3 3" !=
a.
- <3 3' .:
a. B. Understory algae Shallow Mid-depth 8- *"' r a n.Mw(18)
- O fartw (st)
~
60 - p g neartw(17) > [
!i! O fartw(as) l 30 -
g 40 - 8 T l# . E 20 - 20 - ' 10 - 0- -T- 0- - 3 e .3 . ! .a sa # 3* Ga 2 ga 3" 5: l 84 &$ Et si ** 6" i 6" i' s s Figure 3.3.2-6, A. Mean and 95% confidence interval of log number /100 m ) of kelps (1978-1987; station 35: 1982-1987) and B. Percent frequencies and 95% confidence interval of dominant understory algae (1981-1967; station 35: 1982-1987) in the shallow and mid-depth subtidal zone. Seabrook Baseline Report, 1987. 219
Pellota serrata were encountered more frequently in the mid-depth zone. Pt11ota serrata occurred as frequently as Phy11ophora sp. at Station 19 even. though it was not at'its peak biomass (Figure 3.3.2-5). Fellota serraca was significantly lower and Chondrus crispus significantly higher at Station 31 (which is 9.5 m deep) than at Station 19, which is 13.7 m deep (NAI 1985b). Patterns shown by the 1987 frequencies of occurrence were within the range observed historically, with one exception: Pt11ota serrata showed fewer occurrences at Station 19 than in past years (NAI 1988). Also, the frequency-of this species equalled the lowest recorded value (in 1986) at the counter-part farfield station (31) (NAI 1988). Intertidal Fixed Quadrat and Transect Surveys In situ counts of macroalgae in fixed quadrats at the intertidal stations (Stations 1 and 5) were conducted at mean low water (Site "D") and at mean sea level on bare ledge (Site "C") and fucoid-covered ledge (Site "B") habitats. These quadrats were set up in order to monitor the same exact habitat thus eliminating small-scale spatial variability and focusing on temporal variation. Appendix Table 3.3.2-3 shows the occurrence of those species recorded more than once in a quadrat; other less common taxa (i.e., recorded only once in the study to date), were not-included. Since the quadrats (sites) have unique characteristics, each will be described in turn. The Bare Ledge Site (C), at the upper edge of the MSL (mean sea level) zone, was characteristic of " bare" ledge in the area, that is, ledge not continuously covered by macroalgae. Although highly seasonably variable, barnacles have been common in this. quadrat (see Section 3.3.3 for faunal coverage). During the spring the annual greens, Urospora pencilliformis and Ulothrix flacca (at both stations), and the red algae, Bangla fuscopurpurea (Station SMSL), have been abundant. Small, immature perennial Fucus sp. plants have also been found in this quadrat; although they occurred-fre-quently, their percent cover was usually less than 10%. Temporal variations in these fuccids have been observed over one to two year. periods (Appendix 220
l l Table 3.3.2-2). These variations are apparently not related to any seasonal or yearly trend but likely to plant loss and slow regrowth. Algae settlement ) and growth are controlled by balancing the opportunity for settling on I available space versus the effects of predation. Spatially, the bare rock quadrats have been generally similar, although temporal variations in Fucus sp. appeared spatially independent. The more persistent red, Porphyra sp. was unique to' 1MSL, while B. (uscopurpures was unique to 5MSL (in these fixed quadrats). The Fuccid Ledge Site (B), in the mid-MSL zone, is situated in the area of maximum fucoid algae cover. The perennial, Tucus vesiculosus, has been the major species within the quadrats, although some F. disticus v. edentatus and Ascophylum nodusum (Station 5M5L) have been recorded (Appendix Table 3.3.2-3). These fucoids were quite persistent and frequently occurring, although relatively low (<40%) coverages have been recorded at times, e.g., December 1982 (both stations) and winter / spring of 1984-1985 (at 1MSL). The perennial red algae, Chondrus crispus and Mastocarpus stellatus occurred as understory algae at both stations, but in relatively low amounts (usually <10% frequency); the latter species was more persistent. Few other algae were common in these quadrats, except Porphyra sp. and Spongomorpha sp. both (both at Station IMSL only). Fixed line transects have also been surveyed in the MSL zone from l 1983 to 1987 to quantify the areal coverage of the fucold algae. In the fixed areas studied, the percent frequency of occurrence of Ascopy11um nodosom was similar at both stations (Figure 3.3.2-7) while Fucus ves/culosus was almost twice as frequent at the nearfield station (1MLW). Some I F. distichus var. edentatus was also recorded at IMLW, but none at the farfield site (5MLW). The degree of among year variability was low (21-33% CV) for the two dominant fucolds (Figure 3,3.2-7). I i The quadrat at Site D, in the MLW (mean low water) zone, is situ-ated in the area of maximum red algae cover. Chondrus crispus and Mastocarpus stellatus dominated this zone; together they typically cover 80 l to 100% of the substrate. Spatially, the frequency of occurrences at the two ! l 221
100 - 100 - 100 - Ascophyllum Fucus - Fucus distichus nodosum vesiculosis var. edentatus 80 - 80 - 80 -
@ 60 - 60 - 60 -
W O - E
# 40 - 40 - 40 -
20 - 20 - 20 - 0- 0- 0 , , 1MSL 5MSL 1MSL SMSL 1MSL 5MSL STATION l Figure 3.3.2-7. Mean percent frequency and standard deviation of fucoid algae at two fixed transect sites in the mean sea level zone (1983-1987). Seabrook Baseline Report, 1987. 222
- -- - - - - )
l l
)
l i stations' quadrats were generally similar for these two dominants although there has tended to be a greater frequency of C. crispus at 5MLW. Spatial differences included the occurrence of Tucus sp. which was persistent only at l IMSL as overstory, and Corallina officianalls which was persistent at SMSL as an understory species; small scale vertical differences between stations likely contributed to these species occurrence differences. l i 1 3.3.2.2 Selected Species s Laminaria saccharina l I d Laminarla saccharina has been one of two dominant canopy-forming kelps in the shallow subtidal zone (1 to 9 m deep) surrounding the Inner and Outer Sunk Rocks. Average seasonal densities (1979-1987) of adult plants 8 ranged from 1 to 11 plants /m at the nearfield station (17), while average percent cover ranpd from 3% to 43% (Table 3.3.2-4). Density varied greatly 1 1 due to variability in the amount of substrate available for settlement l combined with the contagious (clumped) distribution of these plants. At l Station 17, annual mean densities were greatest in 1979 (981 plants /100 m 8 ), decreased to 285 plants /100 m' in 1982, and remained at that approximate !1 level through 1987. The most precipitous change in density occurred between I April and July 1982 with an 85% drop in density. There had been a very large and dense stand of kelps in the western portion of this station which has since diminished since 1979; this has contributed to changes observed in 1982. It can be hypothesized that due to scouring from the storm of 1978 1arger amounts of substrate became available for Laminaria settlement, which 1 resulted in higher densities in 1979; over time these stands may have diminished to a more " typical" level (as in 1982) as substrate became recovered with understory algae. Over the last six years (1982-1987) when both nearfield and farfleid stations were monitored, however, annual differences were not significant (Table 3.3.2-5). Average numbers of plants per quadrat were similar between the nearfield (17) and farfield (35) 223 I
a 7ABLE 3.3.2-4. SEASONAL AND YEARLY MEAN ABUNDANCE AND PERCENT COVER OF LAfflNARIA SACCHARINA FROM TRANSECT STUDIES IN THE SHALLOW SUBTIDAL ZONE. SEABROOK BASELINE REPORT, 1987. 2 NO./100 m % COVER NO./100 m % COVER 17 35 17 35 17 35 17 35 1979 Apr 1052 35 1984 Apr 311 209 9 9 Jul 888 43 Jul 252 209 13 18 Nov 2004 34 Oct 555 152 20 8 Mean 981 37 Mean 373 190 14 12 1980 Apr 724 18 1985 Apr 340 159 16 5 Jul 678 32 Jul 212 264 16 19 Nov 754 37 Oct 286 302 19 6
.Mean 719 29 Mean 279 242 17 10 1981 Apr 719 21 1986 Apr 278 757 17 21 Jul 519 24 Jul 167 188 8 16 Nov 500 20 Oct 169 245 7 20 Mean 579 22 Hean 205 397 11 19 1982 Apr 588 25 1987 Apr 71 195 5 13 Jul 88 669 6 36 Jul 433 550 22 21 Oct 179 409 14 14 Oct 367 743 12 17 Mean 285 539 15 25 Mean 290 496 13 17 1983 Apr 83 104 3 5 Jul 217 376 13 18 Oct 693 207 13 11 Mean 331 229 10 11 1>0nly plants measuring 2 15 cm long were counted.
Station 17 = nearfield; Station 35 = farfield. 1 l 1 224
TABLE 3. 3. 2-5. RESULTS OF SIGNIFICANCE TESTS ON MACROALGAE SELECTED SPECIES, CHONDRUS CRISPUS AND LAMINARIA SACCHARINA. SEABROOK BASELINE REPORT, 1987. A. CEONORUS CRISPUS BIOMASS (g/m2 ) Temporal (Year) Comparisons (1978-1987): one-way ANOVA of Log (x+1) means a STATION df SS F VALUE SIGNIFICANCE 1MLW 9 0.495 1,62 N.S. 17 9 0.325 0.67 N.S. Epatial (Station) Comparisons (1982-1987): Paired t test of sample means STATIONS t SIGNIFICANCE COMPARISON 1MLW VS. 5 MLW 2.59
- Nearfield greater 17 VS. 35 2.92 ** Nearfield greater B. LAMINARIA SACCHARINA DENSITIES (No./m')
Temporal (Year) Comparisons (1982-1987): Wilcoxon's Ranks Test STATIONS VARIABLE SIGNIFICANCE 17 and 35 years N.S. combined (1982-1987) Epatial (Station) Comparisons (1982-1987): Wilcoxon's Ranks Test STATIONS VARIABLE SIGNIFICANCE 17 vs. 35 stations N.S. "N.S. = Not significant
* = Significant at p < .05
** = Significant at p < .01 225
stations over the entire 1982-1987 period (Table 3.3.2-5), but the kelp beds were more evenly distributed at Station 17 than at Station 35 (NAI 1985b), evidently because of differences in available substrate. Chondrus crispus Chondrus crispus (Irish moss) was the dominant understory algal l species in the lower intertidal and shallow subtidal zones near the Sunk Rocks (sco Community Analysis section). Destructive samples were collected in May, August, and November from 1978 to 1987 (1982 to 1987 for Stations 35 and SMLW); maximum biomass typically occurred in August at all stations, except 5MLW (Figure 3.3.2-8). Minimum values generally occurred in May at subtidal stations; at 1MLW the lowest values were generally found in the fall. Howevel, confidence limits (calculated for 1978-87) implied a significant difference between minimum and maximum seasonal biomass only at Stations 17 and 35. Blomass values from 1987 generally differed very little from the historical data (NAI 1988). At intertidal Station SMLW, biomass in 1987 wits noticeably (about 50%) lower in May collections than in previous years (N/.I 1988). These data continued to add to the natural variability of the baseline data at this station. l August biomass values at Station 17 ranged from 574.9 g/m' in 1980 q to 1272.7 g/m in 1985 (Table 3.3.2-6). Overall biomass at Station 17 was f significantly higher than that at Station 35 (Table 3.3.2-6). Peak biomass at Station 1MLW was recorded in 1982 (1622.9 g/m'), its minimum in 1978 (459.7 g/m8 ); biomass at 1MLW was statistically different (at p <.05) from the farfield station. ! l l { l 1 226 , j _ _ _ _ _ _ _ _ _ _ _ _ - . - - - - - - - . - - - - - - - - i
n i
)
s7 n8 o9 i1 t -
- a2 t8 s9
- 1 d
- e
- t :
I S cW eL B l M e1 s d t n aa s5 u3 i p ss i n ro ci
- t sa
- ut -
rS d n 1 1 B o7 h8 C91 f - TI o8 s9 7 N t1 O i i I T m i : A l 5 T 3 S e
- - c n7
- e1 d
5 i s 3 f n B no oi . ct7 R a8 E %t9 T O S 5S1 _ U B 9 G , , _ U W A M P i d rt ner ab o E E O mp
) ee
_ - movR
/Ne
_ m gdi n ( nl 7 ae - 1 s s . B st a asB mu o gk i uo bA o r n aya
,b eae MMS 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4
1 2 1 0 1 8 2 4 2 8 2 3 3 e r u g eE$ 58" ' EeE !m 2 i F ll l
2 TABLE 3.3.2-6. MEAN BIOMASS (g/m ) AND STANDARD DEVIATION (SD) 0F C#0NORUS CRISPOS AT BENTHIC STATICNS 17, 35, 1MLW, AND SMLW IN AUGUST FROM 1978 TO 1987. SEABROOK BASELINE REPORT, 1987. SIIALLOW SUBTIDAL INTERTIDAL STATION 17 STATION 35 STATION 1MLW STATION SMLW YEAR (NEARFIELD) (FARFIELD) (NEARFIELD) (FARFIELD) MEAN S.D. MEAN S.D. MEAN S.D. HEAN S.D. a 1978 860.3 535.7 NS 459.7 532.9 NS 1979 713.8 301.8 NS 638.6 138.1 NS 1980 574.9 282.4 NS 797.8 262.1 NS 1981 1113.8 384.2 NS 917.3 558.1 NS 1982 593.6 194.5 491.9 234.9 1622.9 345.3 1147.4 174.4 1983 853.8 243.5 663.4 388.9 1539.6 129.1 994.3 461.8 1984 782.1 251.5 484.7 344.2 1612.4 263.8 457.3 321.7 1985 1272.7 366.2 544.3 428.4 1203.5 179.9 530.9 479.7 1986 1193.3 329.7 523.7 343.2 1154.4 723.1 857.7 258.0 1987 943.5 288.1 673.1 414.2 951.9 263.8 628.6 312.7 ALL YEARS MEAN 890.2 563.5 1089.81 769.4 NS = Not sampled. 228
~
. 3.3'.3. Marine Macrofsuna 3.3.3.1 Algae Covered Ledge Community-General Studies'of the macrofaunal invertebrates off Hampton Beach, NH since 1978 have focused.on the horizontal algae-covered ledge habitat in four
~
depth zones: intertidal _(MIN and MSL), shallow subtidal (5 m), mid-depth (9-12 .n) and deep (18-21 m)(Table 4.1-1). -Nearfield stations near the intake and discharge areas have paired farfield counterparts near Rye Ledge in the ; same depth zone (Figure 4.1-3) for an optimal impact assessment design (Green 1979). Macrofaunal studies include a community analysis of intertidal and subtidal habitats, a detailed examination of key species (see Section 3.3.5 also) and an investigation of the near-surface and bottom fouling community (see Section 3.3.4 also). l l Numbers of Taxa and Total Abundance Numbers of taxa and total abundance have been used to monitor spatial and temporal trends in the macrofaunal community. These parameters have shown broadscale changes in relation to depth. The number of taxa generally increased with increasing depth, and nearfield stations had higher numbers of taxa in comparison to farfield stations (Figure 3.3.3-1). Total abundance showed a general decrease with increasing depth (Figure 3.3.3-1), mainly due to decreased numbers of mytilids (see Section 3.3.5). .j The intertidal area had highest abundance of all of the benthic stations, and nearfield and farfield stations had lower numbers of taxa than subtidal counterparts (Figure 3.3.3-1). Nearfield Station 1MLW had higher numbers of taxa and total abundance than its farfield counterpart, Station SMLW (Figure 3.3.3-1). The presence of boulders at the farfield site may decrease available habitat space, in turn decreasing the total abundance and 229
300 280 260 240 220 - 200 1 g 180 F 160 o 140 g 120 , Z 100 80 60 40 ., 20 , 0 1MLW SMLW 17 35 18 31 19 13 4 34 STATION 200000 g 180000 160000 140000 h 120000
$ 100000 80000 60000 d
2 4o000 20000 0- i i i i i i i EmM i i i 1MLW SMLW 17 35 16 31 19 13 4 34 STATION l Figure 3.3.3-1. Number of taxa and overall abundance (No./ square meter) over all years (1978-1987, stations IMLV, 17, 19, 31; 1982-1987, SMLW, 35; 1979-1984, 1986-1987, 34; 1978-84, 86-87, 13, 4, 16) at intertidal and subtidal benthic stations. Seabrook Baseline Report, 1987. s
,N 230 1
_W. I
l number of taxa. The 1987 abundance levnis at 1MLW dropped from the extremely high levels recorded in 1986 to levels similar to previous years (Figure 3.3.3-2), in part due to decreases in myt111d abundances from their peak 1986 levels (see Section 3.3.5). The number of taxa in 1987 was the lowest ever recorded at intertidal stations: 60 at Station 1MLW and 64 at Station SMLW j (Figure 3.3.3-3). This could be a result of the prolonged period of low salinity in April and May (see Section 3.1.1). Bottom salinities were below 1 31.5 ppt for two to three months at Station P2. In addition, 1987 bottom temperatures at this station were approximately 3 C below average in August and September (Figure 3.1.1-1). The shallow subtidal stations (5 m), Stations 17 and 35, had higher I numbers of taxa than their intertidal counterparts but lower numbers than mid-depth and deep areas (rigure 3.3.3-1). The nearfield station had a higher number taxa (227) in comparison to the farfield area (195) but slightly lower overall abundance (Figure 3.3.3-1). Number of taxa decreased at both stations in 1987, although the decrease was slight at Station 17, remaining within the range of previous years. Total abundance in 1987 decreased at Station 17 following peak levels in 1986 (Figure 3.3.3-2), due to decreases in Mytilidae and Locuna vincta, which were exceptionally high in 1986 (NAI 1987b, 1988). Mid-depth (9-12 m) stations, Stations 16, 31, and 19, continued the trend of increasing numbers of taxa and decreasing abundance with increasing depth. Numbers of taxa were consistently higher at Stations 19 and 16, where algae-covered ledge predominates and mussel beds comprise 25-40% of the habitat (Figure 3.3.3-1). In comparison, Station 31 was predominantly com-posed of mussel beds (60%) with cobble and algae-covered rocks also present (Table 4.1-1). Numbers of taxa in 1987 were the lowest encountered since sampling begal (Figure 3.3.3-4). Abundance levels at Station 16 were higher than at Station 31 which in turn were higher than at Station 19, because of the varying numbers of mytilids (Figure 3.3.3-1). Abundance levels in 1987 at Station 19 decreased from peak 1cvels in 1986, (Figure 3.3.3-5), dimin-ished by lower mytilid densities (see Section 3.3.5). At Station 16, total j abundance was the lowest recorded since sampling began in 1980 (Figure l 3.3.3-5). 231 J _ _ - - _ . _ _ _ _ _ _ _ . _ t
l 1000000 - gg 9g , INTERTIDAL (1MLW) E 800000 - w b 700000 - , 600000 -
$ 500000 - .
= -
1 0 400000 - ,
- 300000 - ,
N j 200000 .. 100000 - " " O , , , , , , , 1985 1986 1987 1978 1979 1980 1981 1982 .1983 1984 YEAR l l 100000 - ' SHALLOW SUBTIDAL (17) 90000 -
@ 80000 -
70000 - ( h y 60000 - , 5 50000 - 40000 - . d 30000 - z y .. 20000 - .. 10000 , , , { 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 YEAR I ( t Figure 3.3.3-2. Annual mean abundance (No./ square meter) and 95% confidence limits for macrofauna collected in August for nearfield stations 1MLW (intertidal) and 17 (shallow subtidal). Seabrook Baseline Report, 1987. 232
J 120 - INTERTIDAL
,00 .
. 4 4 *
..a..* .,
x 80 - -
>= .
l ' I g . ) O g-K W
- l ID 1 3 40 - !
I 1 MLW (nearfield)
... .. 5MLW (farfield) 20 - ,
i 0 , , , , , , , . , , 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 YEAR j I 140 - SHALLOW SUBTIDAL 120 -
< 100 - .... *****"*- ...
' /
x ,
/ .,
4 .
>= /
g 80 - '., O .
,',:,/
@ 60 -
2 3 40 - Z B17 (nearfield) l 20 - O , , , , , , , , , ! 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 ) YEAR .j Figure 3.3.3-3. Annual number of taxa collected in August at intertidal stations 1MI.W and SMLW and shallow subtidal stations 17 and 35. Seabrook Baseline Report, 1987. 233
140 -
. MID-DEPTH 130 -
y 120 - i-
,. i \ 0 ', ;
\ ,so' , .,,
\ BO "
t 9 70 , , r , , , , , , i 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 YEAR 150 - DEEP , 140 - / , '
$ 130 - '.,
H
./ .
120 - ,/ u, O
'*"....,n..,**" -
...=
( c: 110 - /. w 100 *..."%.,*/ m 2 o 90 - Z 4 (nearfield)
******* 34 If'#f *id) 80 -
70 , , , , , , , , , , 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 YEAR 170 - MID-DEPTH TO DEEP 160 - *
- 13 (nearfield) 4 150 - .
16 (tarfield) x .
< 140 - ., (
130 -
- o
' ~~~ " " " * % ..,
120 - .., a: ,'... g 110 - g < 2 100 - D 2 90 - i 80 - 70 , , , , , , , , , , j 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 i YEAR l 1 1 Figure 3.3.3-4. Annual number of taxa collected in August at stations 16,19, and 31 (mid depth); and stations 4,13, and 34 (deep). Seabrook , Baseline Report,1987. { t 234
80000 - MID-DEPTH (19) 60000 - N E { ) - 40000 - 2 . S t . 7 7 ,,
.T. J, m .
0 ! ( , , . . . 1982 1983 1984 i 1985 i i 1986 1987
.i
)- 1978 1979 1980 1981 . YEAR l l 140000 - MID-DEPTH (16) 120000 - ., a 100000 - ] l 80000 - . h 6 60000 - t 40000 - , 20000 - 0 , . . . . I 1978 1979 1980 1981 1982 1983 -1984 1985 1986 1987 YEAR 1 DEEP (4) 12000 - 10000 - 8000 - . E 6000 - 6 ' Z 4000 - .. " , 2000 - 0 , , , . . . , , , i 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 YEAR Figure 3.3.3-5. Annual mean abundance (No./ square meter) and 95% confidence limits for macrofauna collected in August for nearfield stations 19 and 16 (mid-depth) and 4 (deep). Seabrook Baseline Report, 1987. 235
The deepest stations (18-21 m), Stations 4, 34 and 13, had the highest number of taxa and the lowest number of individuals in comparison to shallow and mid-depth areas (Figure 3.3.3-1). The overall number of taxa has consistently been lowest at Station 13, which has a mixture of algae-covered ledge, mussel beds, and cobble, and highest at Station 4, where mussel beds predominate, with some algae-covered ledge present. Station 34, slightly deeper at 21 m, has been intermediate in its number'of taxa, and is pre-dominantly mussel bed (Figure 3.3.3-1, Table 4.1-1). Numbers of taxa in 1987 fell within the range of previous years at all three stations (Figure 3.3.3-4). Density levels were highest at Station 13 and similar at Stations 4 and 34 (Figure 3.3.3-1). The abundance levels in 1987, while within the range of previous years, were slightly lower than average at Stations 4 (Figure 3.3.3-5) and 34 (NAI 1987b, 1988). Elevated abundances at Station 13 in 1986 were due mainly to high numbers of Balanus crenatus (10,323/m2 ) and Lecuna vincta (4000/m )(NAI 1987a). In 1987, total abundances were similar to those observed in 1986, but instead were a result of high densities of Mytilidae, Balanus crenatus, 4 and #1ste11a sp. all averaging from 4000-5000/m (NAI 1988). Community Structure z The noncolonial, macrofaunal, hard-bottom community structure has historically shown changes related to depth (NAI 1987b). Intertidal, shallow subtidal, mid-depth, and deep areas were distinct in both species distri-butions and abundances. The 1987 collections showed highly similar species / composition to collections from previous years (Table 3.3.3-1). In all cases, based on the similarity in species composition, the 1987 collections i were placed in the group with the majority of historical collections from the same station (Table 3.3.3-1). The addition of 1987 data caused only a few j changes in the within group abundance of dominant taxa, underscoring the similarity of 1987 to previous years. 236
)
SI ' A L A 2 012424 75471 732 75284953 9476077 31 3547 04385881 D M 522443 22487641 98650939 1 385543 274240 33899803 563222 47986433 73200654 5342222 790099 63478090 I T /. 1 31 ' 71 1 1 1 844211 1 7454433 R O ' 1 ~ 0 .- - E N 1 f f l I , T A D E s s s _s T i i i i C l l l a l a I a a I n n n n L s o s s o s o so O . i i i i i i i ii - CF A m r s m m r rt t e m r t r s mra rt e 8 r t A9 N1 X A e n n e t u e n e n nu et e n n e u t r
.enr neo t a
U T i t a ai i t a a i .tp ae aith a u aa A , . p n . . pn
.te a ng t ppt an .t FT T a p e e p .tca . ap ee pe ei caesa nipcst p DR RO CP t
l A M i ce naadas ses a- p . ceaas r s .pnie psiea vnd ee is . srpn anasa p csi v iess . rnpc' nisoc ca ndaas s eie avnapa hl er i msnuea aaaavlh il AE I edlil sdl s ei de1 l sa eil1 su d e1 f dmil MR f N gilil a uil auagt i g1 al ul a gil1 aul i ar1 a i nl arol l aoenagl E ol erei nl einnor l oeienun oreeinu l noeea LE D tit erm ait maut e it t mragu t errmac i ut rt s i rtt umoe AN nt nt ro lt aol cnt t naopll c nt ppol s t cnpos t eracmic - II o yi san ayi naaos yoinaaoa osaanau yaoada yauiaal u E L PMMACA BMHABl PA MPMACBML PACCABM MLPCIJ MJTMLGON DE t S oA CB - NK OO NO ,
/
R e h FB d g t OA /p n r pe E a a ek r SS e hl - da ee I e e coe srg e t t y S dd g g d n uR Y . E n r it r r ii O LF A8 T I
-a h a dna
/oh al h o m, / ,
l s N9 S he c hcc cr - e ak A1 / t g s t s st g dc
- M prl il p ,i in ur i o T8 T eao do eed do oa tR N7 P dh r /r dk/
- ap
/p c lh r e A9 E - ct pt l c ekg N1 D d sn en eo dt e ed as t nd I iio ine en hi nue MT Mdc Dc Mid Da Sd ISL IS RU CG SU IA D ,
YS BN / O S DI EP ETA D LU PO 4 9 1 2 3 1 2 2 6 1 IT MR FS AG E S DCI SM PT f Ul CE ) PB 7 G 8 9 NED AL ) )
, 7 1, 7 tII 4 8, 82 8, TT 8 )
AB Tt
- 1
- 6 8,
6 - - 6 8,
) )
77 SS S) 8 ) ) 9 8, 8 1
) )
88 E Nt S 9 4 770 49 773 - - t l 1, 8 888 81, 888 82
. IA ) ) ) ) ) - - - -) - - - - 78 1 TE 8880 873 9994 99 820 99 AY 7 9 8,9 - 7778 8 7778 77 788 1 1 3 Ti 9999 9999 99 999 t t S 11 1 1 1 61 1 1 1 1 1 1 1 1 1 MM 3 t 8t 91 1 t144 t 3 4 891 t t t 36 ( (
44 1 t 1 756 L1 M 3 1 3 3 1 3 1 31 1 3 131 I 9 E L B A T N OP IU TO AR 1 2 3 4 5 6 TG S oW" t
l
~
Differences in' community structure among stations were indicated'by. differences in densities of dominant taxa as well as the species which are restricted to a certain depth zone. The discriminant-analysis relied on only l 32 of the original 89 species used in the cluster analysis to form the-l ' station groups (Appendix Table 3.3.3-1). The most abundant species (i.e., l Mytilidae spat, Pontogenels inermis, Lacuna vincta, Capre11a septentrionalls) were ubiquitous, and contributed little'to the. discrimination among stations. Less-abundant species, such as Nucella lapillus, Callioplus laevlusculus, Jassa falcata, Herels pelagica, Jaera marina, and Musculus niger, accounted. for the majority of the among-station variability. The intertidal habitat (Group 6) was the most distinct of all nreas-because of the overwhelming predominance.of Mytilidae spat (101,630/m8 ) and the presence of species such as Nucella lapillus, Fabricia sabella, Ryale: nilssoni, and Jaera marina, which were restricted to that area. Other dominants included the molluscs Turtonia minuta,~Flatella sp., and Lacuna vincta, and the amphipod Commarellus angulosus. Intertidal collections made in 1987 were placed in this group based on similar species composition. However, a few of the individual species showed decreases in densities from peak levels noted in 1986, decreasing the-overall group density from the 1978-1986 value (NAI 1987b). These included Mytilidae at Station 1MLW only, and #1ste11a sp. and Jaera marina at both 1MLW and 5MLW (NAI 1987b, 1988). 2 Mytilids at Station 5MLW reached their highest density since sampling began in 1982 (see Section 3.3.5). The shallow subtidal station group (5) has included Station 17-and 35 in all years and Station 16 in 1980-1983 and 1986-1987 (Table 3.3.3-1). Mytilidae was still the predominant taxon, although less abundant than in the intertidal area. Aside from gastropod Lacuna vincta, dominants were 1 peracarid crustaceans such as Pontogenela inermis, Capre11a septentrional1s, . Idotea phosphores, and Jassa falcata (Table 3.3.3-1). Relatively high ; densities of the latter two species, along with Callioplus leevlasculus distinguished this area from other areas. The addition of 1987 collections did not change the order of the dominant species, nor drastically alter the ;
.within-group abundance. However, average group abundance levels of all taxa were lower than 1978-1986 levels due to decreases from the 1986 density j- levels (NAI 1987b, 1988). Species composition at Station 16, with depth of j L 10.7 m, was usually more similar to the shallower Stations 17 and 35 becauso~ )
of the predominance of uniform algae-covered lodge, causing increased biomass of algae (see Section 3.3.2). This, in turn, increased numbers of sub-
)
dominant herbivorous species such as Lacuna vincta and Idotes phosphorea, . which increased the similarity of this station's species composition with that of shallow subtidal stations. Furthermore, flat ledge at Station 16 (with fewer mussel beds and boulders) prevented the accumulation of sediment and detritus, making it less suitable than other mid-depth stations for species which rieed sof t substrate such as Nichomache sp. , Cistenides j granulata and Cerastoderma pinnulatum. l I Mid-depth areas (Group 3) were characterized by a predominance of ] Mytilidae spat, with other molluscs (e.g., Elate 11a sp. and Anomla sp.) and amphipods (e.g., pontogenela inermis and Capre11a septentrionalis) occurring in high numbers (Table 3.3.3-1). Stations 19 and 31 in most years were characterized by this assemblage, as were deep Station 13 and mid-depth Station 16 in one or two years. The 1987 collections at Stations 19'and 31 were similar to previous years, and thus placed in the same group. Densities of dominant molluscs Mytilidae ard liiatella sp. In 1987 decreased from the extremely high values recorded in 1985 and 1986 (see Section 3.3.5 and NAI 1987b, 1988). Stations with depths greater than 15 m formed several loosely-associated deep station groups. All differed from shallower stations in the i decreasing influence of molluscs, particular! ' the overwhelming predominance of Mytilidae spat, and the increased importance of crustaceans and other taxa. The majority of collections at deep stations (4, 34, 13) were placed in two groups. In some years, at Stations 4 and 34, peracarids (Pontogenela inermis, Caprella spp.) Astertidae, and molluscs (Anomia sp., Husculus niger) were the dominant taxa, forming Grcup 4 (Table 3.3.3-1). The 1987 collec-tions at Stations 4 and 34 were placed in Group 4 based on the similarity of 239
( { l l their species composition. In other years, at Stations 13 and 34, Balanus spp., along with molluscs (Mytilidae, Anoaria sp., Lacuna vincts and Niatella sp.) were the most abundant taxa, causing these stations to be distinct from other collections, forming Group 2. Collections made at Station 13 in 1987 were placed in this group, in part due to high densities of Balanus spp. (4698/m') (NAI 1988). The high within group .ibundance of Balanus crenatus is i deceptive, however, as it is heavily influenced by Station 34 in 1984, where Balanus crenatus averaged 12,233/m' (NAI 1985a), and 1986 at Station 1?, where this species averaged 10,323/m' (NAI 1987a). A third group of four station collections, including mid-depth 19 and 31 and deep 4 and 34, was formed because they were unlike the other assemblages in having moderate numbers of Mytilidae sp. and Flate11a sp. but low numbers of Balanus spp. No collections from 1987 showed a similar species composition to this group. 3.3.3.2 Intertidal Bare Rock. Fucold Ledge, and Chondrus Communities Important species on fucold-covered and bare rock ledge habitats at mean sea level (MSL) and Chondrus zone habitat at mean low water (MIM) were enumerated triannually at fixed stations on Outer Sunk Rocks (Station 1) and Rye Ledge (Station 5). The bare rock areas supported low percentages of algae such as Porphyra spp. at Station 1 and Fucus spp. mainly at Station 5 f (Section 3.3.2). The predominant macrofaunal resident was Balanus spp., which had slightly higher frequencies in April following the spring recruit- ] ment period, than in July and December (Table 3.3.3-2). Gastropods Littorina littorea (at StatIan 5) and Littorina saxatills (at both stations), chtef consumers of Fucus sp., were also important constituents of the bare rock community, showing lower frequencies in April than in July or December. I Mytilidae spat occurred in low frequencies in July and December. Patterns of faunal distribution in 1987 were similar to those observed in previous years ! with one exception. Nucella lapillus, normally not encountered in the bare 2 rock zone, occurred in all three months in 1987 at Station 5 (NAI 1988). ( 240
1
,I
( - -
- a
.*a ;j2
- - - - - 1
) g "9 a9 =* *a -
*e "" **
e
* : e _
o l - IN e? 3-
?
e i-s E 85 -
?s e
s -s .! l lI i a - i. e e? e s ?i e s ;8 n i? e
-s -s j c .
0 ! i Y - - . l
.e
~1 i 3 8 .E 8 4
.;_ .5a mi g 8 -
~a_. a a 4 ug _ _ _ g - _
g - ; .- - - - - g
.; .; mr n e . ma ..me "sa 3 R_
~
W g
*a _
j e _ _o a_ a
. ; ; - - - - i h g *5 5 ;;f ; 5 *a* 5 [ "fNf g_---
$2 p
u 8 a:
- j ,
2 t 4
~
a et r ~f
~ ~
4 g 1 e e e : - e e e - - N o i i u" W W ; G i eg mt .R a _ a_
~R me
~ag
.?
<s-
.2 af o
r - - ; - 8 "
.? mE se m! .. .R .? s2 .; .?
In. % e a a -
-a_
e a_ e
^ ~ ~
g c ci c; c c7 c c7 ci ci c; gB ar er ar ar ar ar ar er er ar e
- .e i. n t. .e .e .e v. _e _e i. _n - _e N
A A E
$ 5 $
s a lo a :
$ G : 3 g
- 4 4 i 3 E r *
, .a.
. - 2" a 8 8 8 4 : :
$ 2 3 3 3 241
5 9 1 _ 8 8 6 8 - C 8 - 34 6 - 9 - _ E 65 - 50 66 D 1 0 5 5 , t E 1 t 3
# 8 E
E 9 1 N I
) 1 )
Z 5 0 1 4 y 9 6 00 4 l S I 3 - 7 - 00 1 - u U t U 91 23 12 33 J J 7 2 ( - 1 im I t i e 0 c 0 n N i C I ) 1 ) s 5 2 5 0 9 7 7 0 s R 4 - 1 - 5- 41 u P 94 40 70 9 - n A 5 1 5 5 a E I ( 7 l t a B
) ) ) d C 5 5 1 6 n.
a E 27 57 00 05 D 1 - 1 - 1 - e 0 1 0 a I t 1 d i l K i C t O . 1 ) 1 y R I 0 8
)
4 M U 64 63 00 04 - E J 1 - - ( r R 0 0 0 o A t t t f B d o
) ) )
h t 0 5 1 4 e R 02 0 - 00 09 m P - 0 ( - A 0 t 0 t t t c a t n I ) 1 o C 0 0 0 0 0 ) c 5 6 - E 31 31 5 - 0 - t D 8 - - 33 0 n 3 0 1 E i 4 E ( o t r t E G s D ) 1 1 1 e . I 0 0 0 1 i) I L U 0 0 0 8 cs D J 31 9 - 1 1 81 7 - 7 - ee pc
- 43 I
O 5 0 5 1 sn 3 t 2 i a C i ( gt U ns F on
) mi 0
I a 0 1 r R 0 0 5 I se P 21 62 02 0O eh A 8 - - 1 - I it 1 2 2 E 0 ( ro a ( vl l ya 1 i l 1 c ne ag ne ag ne ag ag ne nr in in eo i n in uf da da da da q er er er er ee mi mi mt mI r c f n e
) t r 1 5 1 5 nr . .
d eul r e ccee u rcvt n eoea i p l w t f n goau o n eo C i ysl ( t c s unnn u peaa 2 l l muee oqmm 3
- i p
cer , , a ff77 3 e l o 66 a t99 3 d a d n1 1 i l oe- - I I l i l e h e25 t r66 B t c e A y T M N u a M p911#9 "oM iI ,l
w ' l l Fucold-covered ledge areas at mean sea ~ level were characterized. , by a heavy cover (over 80%) of the perennial algae Fucus spp.-(mainly ) F. vesiculosus), with an understory of.perentilal red algae (#astocarpus stellata and Chondrus crispus). Highly-seasonal annual algae occurred in l spring or spring.and summer, particularly at Station 1 (Section 3.3.2). ) Hytilidae spat was the most' common taxon at Station.1, with high. percentages during all.three sample periods (Table 3.3.3-2). Mytilidae usually did not-
.. 1
,show high frequencies at Station 5, Balanus spp. was'also..an important !
member of the fucold ledge community and was more' frequently encountered at
~
Station 5. As on bare rock,. frequencies were highest in April--following i i spring recruitment and lowest'in December. Balanus frequencies were exceptionally low in 1987 at Station 1 (NAI-1988). Nucella lapillus occurred mainly on the fucold-covered ledge, most commonly encountered in July. Other. Important gastropods were Acmaea testudinalis,and Littorina obtusata (most frequent in July and December) and Littorina littorea (almost exclusively occurring at Station 5).
)
{ The intertidal community in the mean low water zone, the "Chondrus
]
zone", was characterized by rock ledge with'a thick cover of red algae, j mainly Chondrus crispus and Mastocarpus stellata. Fucus spp. uere also fre-quently encountered at Station 1 only (Section 3.3.2). Of the macrofaunal species that were monitored, Nucella lapillus and Mytilidae spat were' the most frequently encountered. At Station 1, Nucella were more abundant in l July than in April or December (Table 3.3.3-2). This is' consistent with other studies which show adult Nucella to be active from May through October, while juveniles tend to be active throughout the year (Menge 1978). On Rye Ledge (Station 5), Nucella was less-frequently encountered in July, a sea-sonal pattern that was reversed from'its nearfield counterpart. Seasonal movements of Nuco11a appeared unrelated to those of its main prey, Mytilidae. Mytilidae had medium-to-high frequencies in April and July at Station'1, with generally lower percentages in December. Mytilidae, historically not common l at Station 5, settled in large numbers between December'1966 and April 1987, only to decrease by August (NAI 1987a, 1988). No relationship with abundance l levels of either species at mean low water or with the fucoid community at 243 i 1
l . 1 I mean sea level.were noted (NAI 1987a, 1988). Another important species in l this community was the gastropod Littorino littorea, which occurred at Station 5 only throughout'the year. Acmaea testudinalis was enumerated in low-to-moderate frequencies at Station 1 in all years and Station 5 in 1985 only (Table 3.3.3-2). Seasonal distributional patterns observed in 1987 were similar to previous years. , 3.3.3.3 Subtidal Fouling Community Data collected from subtidal bottom panels gives information on recruitment of benthic macrofaunal species. Balanus spp. (mainly Balanus cronatus, with some Balanus balanus) typically settled by April. Recruitment continued in some years after the April sampling period so that densities were higher in the August sempics, while in other years April nampling occurred near the settlement peak, so that densities were lower in August (Table 3.3.3-3). Densities in December were consistently low, as Balanus populations disappeared as a result of mortality or disturbance. The 1987 panels showed this same pattern. Balanus spp. densities were higher at Station 31 in all years except 1984. Anomia sp. had a pattern of late-summer-fall recruitment. Although low densities of Anomia sometimes occurred on panels by August, numbers were typically highest by December's collections (Table 3.3.3-3). Similar den-sities in August and December collections in 1984 suggested an earlier set than other years. In 1987, December densities were lower than average at Station 31 suggesting recruitment was late or unsuccessful. Nearfield and 3 farfield stations showed similar levels of Anomla, i Flatella sp., another sessile mollusc, showed highest densities by August collections, with most disappearing from panels by December. Den-sities in 1987 showed a similar seasonal pattern (Table 3.3.3-3). Numbers were generally higher at Station 31 than at Station 19 (1987 was an excep- f
\
tion), a pattern not borne out in the natural environment. Especially bish
\
\
244
1jj IIllllIl) l )' llJ 2 0 9 1 5 3 1 9 C 6 6 5 1 3 t B E 6 . t D 1 T 1 . y E G 0 7 4 7 8 5 1 2 B U 5 1 6 3 9 7 7A 7 1 8 2 3 5 E 6 9 3 1 T A 1 . R 3 0 2 0 1 0 '7 7 T S R 8 6 0 1 1 D o 0' 0 9 8 1 9 5 P 2 0 8 S t 2 4 2 2 6 3 t A 2 4 6 5 S D 6C 7 I 8E 9 9 7 0 4 5 1 - A 9D 1 5 2 6 7 C M 1 0 4 1 E
)
1 D E R C 5 6 5 6 0 8 0 0 M 3 U E 2 4 9 6 2 1 8 8 A 6 6 1 8 4 8 0 S .D 1 1 3 E 1 9 8 2 6 5 _ O 7 M 6 4 P 6 X
~
9 E 0 0 4 4 5 6 9 8 1 - G 6 9 8 0 4 2 0 1 S kUA t 3 2 9 1 1 3 4 2 9 7 0 3 E 9 2 1 2 6 T t 1 1 6 9 n I 0 8 0 0 0 1 1 1 1 6 6 2 , R R 0 7 4 U P 5 9 8 O A 2 1 9 F 1 E - 1 L C 0 0 0 0 2 2 9 5 6 1 0 0 9 1 9 5 8 - A E 4 1 9 D 7 5 8 4 9 4 4 3 D W 3 1 S 0 6 2 3 3 0 S ( 5 5 2 - 0 3. I 1 1 A S I R 3 8G 9 0 4 0 7 2 8 5 0 6 9 6 9 1 0 0 R A _ T' 9U 4 3 1 3 3 E G N 1A 1 4 1 Y U A D L 0 0 1 0 0 O 0 0 L A R 3 0 A 4 4 3 2 1 7 3 3 X P 6 1 N 4 8 4 4 9 7 7 6 A A 2 5 R A 3 6 7 2 3 9 T 3 O E 6 6 2 7 7 E F N L I I C 0 6 7 7 S S S S D . S E 2 9 8 M M M M S - S D 9 3 I E 1 S N ~ O 4 D 0 3 0 0 S S S S I E 2G 5 2 MM MM T T . 6U 2 0 A _ C7 9A 9 3 I 6 1 V E9 E1 1 E D S , 0 3 0 0 S S S S D FT R 0 0 M N MM R 5 4 1 0 1 1 4 1 OR P 6 8 A 2 6 1 O A 1 2 B D 7 8
) P 8 B S 0 6 2 E A mR C
T S 1 2 r . 4E
/ E 1 S M
8 7 S M S M S M S M S M s M-1D D 2 l R t 9 L A P 1 . RE A 6 ES 1 N n8 _ PA 6G 0 S 0 S S S S S A 5 3 1 0 1 1 3 3 i9 _ ( B 9U 5 9 M M M M M M E N 1 4 < < 1 1 - 1A I A 5 4 e ._ Y 7 E 1 6 , .de T I 1 4 ad mu IN S l I R 0 S 0 S S S s S ec D P 0 M M N M t I M rn . DE A 6 D E T . S 7 9 1 1 3 9 1 i 1 3 9 1 1 3 9 1 1 3 ei w sn no s _ AS 9 1 3 9 1 3 9 1 3 9 1 3 a at a ta at a ta at oi MI 1 1 1 1 t t t it IE S S S S S S S S ta . Tl . . . . . . . . ct SA a at a ta at a ta at eu EP t S S S S S S t S S t l p l m 1 d oo cc 3 e
- l rr 3
p bb ee 3 p p p p m p s a mm
. p . s s ee 3 s p e s p e cc s a a s a a t ee E A s l d s l d o DD L X u a l i u a l i N B A n i e l n i e l yy A T a m t i a m t i = ll T l o a t l o a t nn a n i y a n i y S B A H M B A M M M ~ a (O O _
nw
densities on bottom panels in 1984 were reflected in higher densities in the natural environment in 1984 (NAI 1985a). Mytilidae spat generally had settled on bottom panels by August, with numbers diminishing by December (Table 3.3.3-3). In the natural environment, small mytilids appeared from August through October, but information from surface fouling panels suggests that settlement can take place throughout the year. Few of these newly-settled mytilids survived through the winter in the natural habitat or on artificial substrate (NAI 1985b). Densities on bottom panels at Station 31 were usually much higher than at Station 19, a pattern which also occurred in the natural habitat (Section 3.3.5). However, in 1987, densities on bottom panels were similar between the two stations, unlike densities from the natural habitat. 3.3.3.4 Hodlolus modiolus Community As part of the subtidal nondestructive program, Nodiolus modlolus populations were enumerated by divers along randomly pre-selected, radiating transects at selected stations. Previous reports have demonstrated that there has been little seasonal variability in density levels (NAI 1985b). Over the eight-year period 1980-1987, no significant difference was detected { between nearfield and farfield stations by a Wilcoxon's signed rank test (Table 3.3.3-4). Significant differences were detected among years using a . Kruskal-Wallis test (p < 0.001, DF = 7). Densities were highest in 1982 and 1983, averaging over 110/m' (Table 3.3.3-4). In subsequent years, annual ( mean density was less than 100/m 8 at.both stations. The 1987 densities were lower than the 1980-1987 average at both stations (Table 3.3.3-4). Despite year-to-year fluctuations in #odlolus density, the community as a whole can i be relatively persistent and is an important refuge from large predators for macroinvertebrates. At the 8 m depth off Portsmouth, N.H., Nodlolus beds f persisted for over five years. However, survival depended on the ability of Nodlolus to avoid predation by Asterias vulgarls or dislodgement by attached i kelps, which in turn are regulated by grazing sea urchins (Witman 1985). 246
l n S L R L A 1 4 5 2 A E 0 5 9 5 . Y 1 L A D I T B 7 i t 8 S 9 7 0 7 _ 1 9 5 6 % _ T _ A ._
- 1 D 2 T .
M 6 W 8 2 2 M 9 0 9 8 1 9 3 6 4 S U L O I
)
W 5 M 8 9 7 6 3 4 S 1 7 4 9 4 U L_ O I ._ 3 . W 7 M 6 9 4 F 1 8 O , 9 7 5 8 8 1 9 5 8 3 N T O R I O T P A E I R V 3 E E D N 8 I 9 2 6 6 0 D L 1 1 6 1 5 R E 1 1 _ A S _ CAB I A T K S O O 2 ORB I 8 9 2 0 1 4 A A 1 3 6 2 6 E 1 1
)
S 2 m . 4 7
/ 8 1 9 1 1 8 R - 9 8 5 3 4 E 0 1 0 4 9 5 P 8 1
( 9 1 Y T . I S S E N O 0 DI D T 8 9 8 8 9 ) _ A 1 9 4 1 % 8 . N T 1 0 - A S E 0 P T C = L E A St p ul ( _ t S R A _ I N N 1 A T A D A D 3 E S M ES P n o 4 i
- t 3 a t
3 S 3 = N E O 9 L I d 1 B T l d ) A A e) l n T T i 9 e1 o S f 1 r ( i 3 i f ( t a r a e a t _ N F S
)
h&N ll
t 3.3.4 Surface Foulina Panels l The fouling panels program was designed to study both settlement patterns and community development. The short-term (ST) panels provided information on the temporal sequence of settlement activity, while monthly sequential (MS) panels provided information on growth and successional patterns of community structure. Surface fouling panels have been collected at nearfield (19, 4) and farfield (31, 34) stations since 1978 (except 34; since 1982). Panels were not collected, however, for the period January 1985 through June 1986. Panel collection resumed in July 1986 and continued through December 1987. 3.3.4.1 Seasonal Settlement Patterns Historically, species richness (number of taxa) on Seabrook short-term surface panels has increased steadily throughout the summer and early fall and decreased in late fall (NAI 1987b). In 1987, faunal richness increased rapidly to a peak in July (except Farfield Station 34, which peaked in June and September), then declined steeply throughout late fall. In 1987, the mean number of taxa reached the lowest point since sampling began in 1978, with only one taxon reported from Station 31 (farfield) in February (Figure 3.3.4-1). The mean number of taxa was the highest ever reported (19) in July at Station 19 (nearfield). For all baseline years combined, the mean j number of taxa ranged between two (Station 4 in March) and 16 (Station 19 in July and Station 34 in September). Fauna appearing on the panels included i bivalves, amphipods, polychaetes and colonials; all groups that have occurred previously on panels. Overall, in 1987 species richness in the offshore nearfield (Station 4) was slightly higher than at the farfield station (34). i However, faunal richness at nearfield Station 19 (near the discharge) was lower than farfield station 31. Over the baseline period, the greatest mean species abundance occurred in the summer and declined through the fall at all stations (NAI 1987b). Stations 4 (nearfield) and 34 (farfield) have followed similar 248
.W N
,W C N
.N ., T -h ., ' *. ,TC 7
8
.s m .C ~ .
O t - O 9
.'- u e
- 1 P
u m e 7 8
.E G -
m
,E
,SGU P
nm i o v9 .U ' ' ) f 1' o1 A i 8 A s e 1 L H ' .. ' m7 1 9
,UL H
- t
.U T T a i J
- 1
- N .
J N c
- - - N O .
. N O i i
.U M .! !
. ,U M l l J
J p l/ Y . Y ee j .A .
, A rcR M M
' R oe 9 T 1
. , PR wd
.P 1
n -
./. , ,RA A 3 n '
,A A
R tii rn eo f i; . M o l t. M vc t . it #
- a 3 o t
.3B t H %
S . F S . F a5k
*A ,A N - '
,A N
x9 a1 J J t
- - - - - - - - ~ - - - .~ d t n 0 8 6 4 2 0 8 6 4 2 O 2
0 3 6 2 0 8 6 4 2 o na 1 1 1 1 1 2 1 1 1 1 e rs m9om$ u.O mmm13z nm uO gms$ e mm- f e f n ihl d c i f r o re eir b c m u C C n
...s .T ..' .W
( k
.O V \\ .N s
s em
'N N i-N m n
- \
, ' ' . ' ' u' e T C [' . m .T C h o
.O N,. u
.E P ..
u O P i ct rd8 r- m e78 v 9 S G
. m 8
.E G
l r1 aa o1 .UA 9 m7 .U np8
.'j/
1 A um7
.- . - L H - / L H a o
- .U T .
- .U T F c
* - J N ,.. - J N f / -
- .U N O M
N O .
~.e J <.:* - .U J M 1 f*.' / -
.Y A Y
A 4 j.* M M
;: 4 3 d 4 .R P 3 / .P R .
l A d n A 3 e n . l i : .R A e o .R A e f i i t r r it M f a M u a a ..' B r t B g e S t -
.R a S
.E i F
N -' .N - N F -N
.A .N A J J
- - - - - - - - - - - - - - - - - ~ - '
0 8 6 4 2 0 8 6 4 2 0 2 0 8 6 4 2 0 8 6 4 2 0 2 1 1 1 1 1 2 2 1 1 1 1 1 mEOm$ u.O mmm1p2 m m
- o.m u,0 @ m s $
m c. L
v temporal patterns; however, abundances at Station 34 were generally higher that at Station 4, especially in October and November. Species abundance patterns at Stttion 19 (nearfield) and Station 31 (farfield) have remained quite similar. The species abundance values for 1987 were comparable to past years, with a few notable exceptions (Figure 3.3.4-2). In July 1987, abundance values at all stations were higher than the mean of all years combined, as were abundance values in February (except Station 34). Compared to other years, mean species abundances were also higher in the winter and early spring at Station 19 and during the late summer and early fall at Station 34. These deviations from the historical mean are specifically a reflection of differences in Mytilidae,' Niatella sp. , Balanus sp. and Jasso falcato abundances (NAI 1988, 1986, 1987a, 1985a, 1984a, 1983a). The dry-weight biomass (g/ pan,el) for short-term panels followed the pattern observed for the seasonal distribution of density and species rich-ness. Historically, biomass values have been normally highest during August and September (1987b). Seasonal trends in 1987 were similar to baseline years, but in 1987 weights at all stations were exceptionally high in September in comparison to previous years (except for 1981)(Table 3.3.4-1). Stations 4 (nearfield) and 34 (farfield) also exhibited substantial biomass increases in August, unlike past years. Total biomass at Station 31 peaked in October, a value which represents a notable increase over the baseline period at this station. High biomass values in 1987 at these three stations were due to dense Tubularia sp. coverage and several large Nytilus edulis 1 individuals (NAI 1988 and photographs in project file). Blomass values at Station 19 were similar to past years. Several dominant taxa on panels were monitored to determine their long-term recruitment patterns at nearfield (19, 4) and farfield (31, 34) stations. A summary of notable differences for each species on the 1987 short-term panels compared to the baseline period is shown in Table 3.3.4-2. ( ( 250 1
.T
.C
~
.C ~
O - 4 O N.- . M . P E N- M M E L
,E P
S L X,
., A G
~ "
%,,.,,s N7 . G 8
9 1 U A L '.'. R E78 V 9 O1
.U A
L
- .t . .U H .
,U H
.:- J T - J T
- N N
^
.N NO UO
- o ,". ,U J M '
- J M
/ , ,~ . Y Y r
A .A
-- .M
- M
~ ~ 9 1
.P R
1 i .Z.
- . . P R
- A 3 . A n .
R n
. R
- . A o A i
t ' M i .M a .
, t a .\
t S -
. . .B F S t
.B F
., - .N N
~ A .A ~ J J 4 3 2 1 o s 4 3 p 3 0
+x ooJmoz<oz2m4 p+* a mOZ4Q3E<
.E
.E
,', N . . ., / /
.O .O
.N-4 M
E . F T C O ' (.- 'A N E .O P T C M ' . 1 .. M. P
- . l P . -
M .E
- ' A .
E . A S
' . R S -
R E 7 V ,8
.' N E 7 e G V 9
., k o3 . G.L A ,-
O3 U A L
. U H L
U H
.!: j:
J T :/* . J T N ; N
- . N O l .
. .NO UM
.U J M J Y
A .Y A y
.: . M M d e 4 . R R -
i a 4 P d 3 . P l f r n a g. . ' A R l i e n o c,y/ : AR A a i t
. " A f r it M
N S t a
;.'.i I.
.B a
F S t a
,..'M('B N- F . F
.N A
.N A J J
_ ~ 4 3 2 1 o 4 3 2 1 0
;+x oos.. moz<az3m< . 7x - moz<ozS4 3
mwF-i l. l
D , 8 5 4 2 2 5 1 1 1 1 1 1 1 3 1 1 1 1 1 1 1 1 1 1 1 3
< 1 < < <
M 5 6 2 2 3 3 1 1 1 1 1 1 3 5 8 8 1 2 7 2 2 9 1 2 1 3 T M N 1 < < 1 1 4 O M C B A 9 6 4 3 8 6 1 9 0 3 8 1 1 3 3 5 2 3 2 7 8 7 6 2 5 2 O N 2 1 2 2 6 < 1 6 4 1 4 2 O I T A T S 9 6 1 0 0 5 9 0 3 9 4 9 1 8 7 4 2 5 5 8 0 1 3 1 8 1 5 R 1 9 5 9 1 2 2 1 2 1 2 1 1 1 1 1 3 2 6 9 A E Y Y 5 2 7 2 9 7 9 7 0 6 3 1 0 4 3 1 5 1 7 7 3 9 1 1 3 4 B A 2 3 0 1 2 2 1 2 1 3 5 S I 1 E N A ' P 8 6 8 4 6 4 8 6 5 7 3 1 1 3 1 8 1 1 5 2 1 1 J 2 5 9 5 G 1 2 1 1 < < < N I L U O F 5 4 6 2 1 2 1 3 2 3 1 3 3 E C J I. 1 1 3 1 1 1 1 5 A < < F R U S M 4 4 4 2 2 2 4 1 1 2 2 2 1 1 2 5 3 1 2 3 1 1 R M E < T-T R O M S 5 7 6 2 2 2 2 3 3 2 2 1 1 1 1 1 1 1 1 1 1 1
. A -
N 7 < < < O 8 - a
- a 9
S 1 S A , H 5 C Tr 1 1 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 I I M 1 1 1 1 B O P ) E L R E I E A N P I 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 1 / L F 1 1 1 1 I gE S
< c < < < < <
A T B H G K I 0 Et0 J 4 4 4 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 D i B < < < < Y A < < < < R E D S 1 4 N O 3 I 9 1 4 9 1 4 9 1 4 4 T 1 3 1 3 1 3 3 9 1 4 4 9 1 4 4 9 1 4 43 9 1 4 4 3 A 1 3 3 1 3 3 1 3 1 3 3 T E L S B A T b a b R 0 1 2 3 4 A 8 8 6 7 8 8 8 8 8 E 9 9 9 9 9 9 9 Y 1 1 1 1 1 1 1 0n rt"
f i TABLE 3. 3. 4-2. DIFFERENCES OBSERVED ON 1987 NEARFIELD SHORT-TERM PANELS a COMPARED TO BASELINE PERIOD (1978-1986 ) AND TO FARFIELD STATIONS. SEABROOK BASELINE REPORT, 1987. I SPATIAL TEMPORAL (NEARFIELD VS. FARFIELD (NEARFIELD 19 VS. 31 ' SPECIES 4,19) 4 VS. 34) i Anomia sp. Station 19 September Station 19 abundance abundance higher com- higher in September pared to baseline vs. Station 31 Station 34 higher in September and October vs. Station 4 Asteridae No Differences Observed Balanus sp. Abundances at 4 and 19 higher in April, May and June (except in April 1980). Niat ella sp. Station 4 higher abun- Station 4 abundance dance during June and higher in July and July (except in 1981). and lower in August and September vs. Station 34 l Jassa (elcata July through November abundance substantially higher at 31 vs. 19 July, September and l October abundance higher at 34 vs. 4 Lacuna vincta No differences Station 19 lower than 31 observed Mytilidae Station 19 higher abun- Station 19 abundance sub-dance in February and stantially lower than March; lower in June 31 July through December. and August Station 4 higher in January, February, July and November; lower in December (continued) 253
l-TABLE 3.3.4-2. (Continued)
. SPATIAL
. TEMPORAL (NEARFIELD VS. FARFIELD (NEARFIELD. 19 VS. 31 SPECIES 4,19) 4 VS. 34)
Nudibranchia Abundance at 31 higher in July than at 19-Pontogenela inermis Density extremely low Strongylocentrotus 'drobachtensis Density extremely low Diatoms No differences observed Obello spp. No differences July percent frequency observed higher at 31 vs. 19 and at 34 vs. 4 Tubularla sp. Station 19 percent fre- High percent frequency-quency higher in extends into November November at Station 4-vs. 34 Station 4 higher in July, and at Station 19 vs. October and November 31 a except at Station 34 which was 1982-1986 and from-January'1985 through July 1986, when no panels were placed or collected, i i l k u 254 ) 1
\ ! j Monthly mean abundances for these short-term panels species are shown for all years sampled in Appendix Tables 3.3.4-1 and 3.3.4-2. The panels' selected ) species, Mytilidae, and Jossa falcata are discussed in Section 3.3-5. ] l i t i 3.3.4.2 Patterns of Community Development l Monthly sequential panels measure growth and successional patterns ) of community development. Ilistorically, settlement activity has been most intense in the summer months and has continued into fall (NAI 1987b). In 1987, the pattern of community development on monthly sequential panels was similar to that of previous years. A comparison of the settlement sequence and survival of species on nearfield (Stations 4 and 19) monthly panels is shown in Figure 3.3.4-3. Similar to previous years, settlement density in 1987 was high in summer months, especially for Mytilidae, Obella spp. and Balanus sp., and persisted throughout the fall. Densities and settlement patterns of Jossa falcata and Flate11a in 1987 reflect closely recent years in which panels were exposed for up to a full year (1982-1984). The hydroid Tubularia sp. settled earlier and more densely at Station 4 in 1987 than compared to previous years; similarly, settlement at Station 19 was slightly moro dense. Balanus sp. was a regular colonizer April through December in 1987 and exhibited higher frequencies at both Stations 4 and 19 in comparison to previous years. Nudibranchia were present earlier at Station 4 in 1987 than in the past, but summer and fall patterns of settlement and density were l similar to previous years, as were those of Polynoidae and Nerels sp. The patterns of community growth and development are generally reflected in the biomass data from the monthly sequential panels (Tuble 3.3.4-3). Over the baseline period, a pattern of increased biomass dry-weights has normally occurred from summer into the fall months (NAI 1987b). Alowever, a sharp decline in biomass dry-weights in 1987 occurred at Station 19 (nearfield) and Station 31 (farfield) in September followed by increases in subsequent months. Stations 4 (nearficid) and 31 (farfield) also showed decreases in December. Consequently, overall biomass weights in ; I 255
STATION 4 5TATION 19 JfM AN JJA50ND JFM AM JJAf0RD nytnidae 15 ......
. . .. . . ..._... 335B artuidaa tw +-
**J mlu
. sw ...... _ ...mamyn jw ...... _.. m l 1m _...... gg Iw .. .. 8 1986' 1986 im _- ggg...g tw ... ..._g gg...... 81 stella sp. 1982 ** aaaaaaa* gjagila sp. 1982 a ...aaaa a.a aa a* iw ... ......g............ iw . . . . . . . . . . . .g . . .g im _ _ . . . . . . . . . . . . . . . . . . im .........iH E H l im a a m agsg tw a EstmlEETS im _ ......g............ iw _ _...g............... l Laga falcata 1982 g aaa E M Lassa fHeats 1982 a.
~~~$lE (QaSQ 1983 ~* -
"aaa EM 1983 aa-ENTIMTZ im ... ... g u m im ..g......... 75 a
i,86 _ 1986 _ . . . o a aa -aaa 1987 1981 J@E sudibranchia 1982 **M ".41 a.......... ... Nudahranchia 1982 a a.ga. ... igg 3 ..................~. 1983 . . . . . . . . . . . . . . . - igg 4 .......... 1984 *a *a~~~ *a
*-*******'*** 1986* '"aa" 1986' 1987 eaaana.." 1987 **aaaaaa" "*
fubularia sp. 1982 aa" fubula_rja sp. 1982 *a$$@ ag iw . . . g 1g. . . . . . iw ...g...... im _ . . . . . . im ......g... a e ......... im ...... im im ... 15 NE
- E **
- gt,31La sp. 1982 a-
.M op,eJJJ sp. 1982 E a5]S ag im _gE * * * * ** - 1983 -
E**- im _
. ..E * -H * - 15 *-E * -
im a gg. . . . . . . . . . . . im a g ... _ tw .. ... ... im _g g...gg...... Balanus sp. 1982 a* "aaa* a- Balanus sp. 1982 **aaaa aa aaan. im . . . . . .ggg . . .g . . . . . . iw ...... g.. .g. . . .. . , im . . . . . _ . . . . . . _ . . . . . . im ......... g. . .g. . . i. 1986' - * * * * * * * * * * *
- Iw' " Elbe * *""* * **
Im a MEMaaaEIB im HaaaETMINIMD Nerets sp. 1982 a* ""a Nerets sp. 1982 aaaa~~~ k 1983 aaaaaaa" aa 1983 aaaaaaaaaa 1984 - -a a" a a" 1984 ~ ~ a a a-1986' a a a *- """a*- 1986' - 1987 aaaaa*"""a" 1987 -* "
- a a a a a a a Polynoidae 1982 g ** *a Polynnidan 19R2 ana *aaaaaan 1983 a " 1983 aa"-
igg 4 ...... ggg4 a ._a a n . a _ a. gg a . . . . . . . . . . . . - 1986' aa a-a a aa- I 1987 *a 1987 aaa I _ present .a 1-251 [requency N$l 26-75 E 76-100
'No fouling panels placed or collected from January 1985 through June 1986. q Figure 3.3.4-3. Annual settlement periods, abundance and survival of major taxa based on examination of sequentially-exposed panels at nearfield Stations 4 and 19. Seabrook Baseline Report, 1987. .
256
_ D 8 5 4 3 3 6 1 7 5 3 7 0 3 9 8 5 4 7 5 1 5 3 0 1 4 2 4 4 1 3 0 7 3 4 0 1 1 9 6 2
. 7 7 8 2 4 2 2 3 1 2 1 3 1 1 7 3 6 8 H -
T N O - M 6 4 7 3 2 4 6 8 9 1 3 5 2 2 0 6 1 ep M 9 9 2 5 2 2 8 8 0 1 4 3 1 4 0 9 3 A 2 8 9 5 8 5 3 2 4 4 7 7 6 5 6 1 1 5 3 1 3 1 2 4 1 5 N O I . T 9 1 9 1 3 2 1 0 1 9 1 0 0 9 A 2 9 7 T 7 1 8 6 S O 4 4 9 5 4 3 2 3 6 0 3 6 5 9 7 8 0 1 1 3 1 5 9 9 8 7 2 2 2 0
, 9 6 1 4 2 1 1 3 2 1 R
A . E Y . 5 9 5 5 9 3 3 7 8 4 3 5 4 2 6 7 4 - Y 3 1 1 9 7 1 4 1 B S 2 5 0 1 4 3 2 6 5 8 0 1 2 1 7 3 3 9 3 5 3 8 3 3 4 5 2 3 2 5 1 4 1 1 1 . E N A P 5 0 1 5 4 7 1 3 2 8 8 5 2 4 0 6 5 G A 7 2 0 4 5 1 4 2 5 0 3 0 1 4 2 7 4 N 7 9 7 8 5 5 2 3 2 3 4 3 4 5 2 3 I 1 1 L U O F 4 4 0 2 6 0 8 4 7 8 3 5 4 5 8 7 9 E C J 2 6 4 7 7 6 7 0 3 9 0 8 3 O 7 7 0 A 5 4 3 5 4 6 1 2 1 2 1 ' 1 1 F 2 2 - R U S 0 8 5 0 5 1 6 8 0 5 1 1 6 7 0 9 7 L J A 7 8 4 0 9 6 3 3 3 7 9 6 8 1 6 5 I 1 3 1 8 1 1 T 1 N E U Q 0 5 2 1 5 2 1 1 7 8 9 8 9 7 0 1 8 E M S 2 1 2 9 6 4 1 2 2 1 2 5 2 1 1 Y L M T N 5 6 2 8 6 3 3 4 4 5 6 8 0 5 7 6 8 O A M 1 1 2 1 9 2 1 2 N . O 7 8 S 9 S 1 A t 4 6 4 7 9 8 2 1 2 6 9 6 1 6 6 5 7 M GT I R 1 2 1 1 1 B O P l E l R e n E 1 2 1 7 8 7 1 2 1 4 8 2 4 1 1 1 1 a '4 F p L <
/ L g E t S A
T B N G K 1 1 1 1 1 2 1 1 1 1 1 I O J E O < < < < < < MR B Y A R E D S
. N 3 O - I 4 T 9 1 4 9 1 4 9 1 4 9 1 4 9 1 4 4 9 1 4 4 A 1 3 1 3 1 3 1 3 1 3 3 1 3 3 3 T S
3 E L B A T a b C d R 8 9 0 1 2 3 A 7 7 8 8 8 8 E 9 9 9 9 9 9 Y 1 1 1 1 1 1
$w
8 1 2 5 D 7 3 5 6 8 3 1 2 0 3 5 7 1 7 3 6 9 8 7 5 7 9 8 6 1 7 0 2 6 8 9 9 1 1 1 1 1 1 M 9 6 4 2 7 8 3 9 7 3 0 1 _ M 4 9 3 6 4 6 1 6 9 5 4 0 _ - 7 2 8 0 9 1 8 7 2 6 1 7 7 9 5 7 4 7 4 5 1 1 1 1 9 0 6 0 1 7 0 2 7 1 5 9 _ 0 6 4 3 9 1 7 9 3 0 3 5 2 l 6 6 6 4 3 5 9 7 9 7 7 7 a 6 3 3 3 9 8 8 8 1 c 0 1 6 6 4 0 9 3 0 3 1 3 3 5 x 5 3 9 2 2 2 9 7 2 4 0 0 9 0 1 9 3 6 2 4 5 0 5 4 6 2 1 2 1 2 2 4 4 3 5 1 ( s l e 0 4 5 5 3 3 1 9 0 1 3 2 n A 3 6 2 7 a 4 9 7 3 0 0 9 5 p 5 11 5 5 6 7 5 2 2 0 4 9 1 1 1 1 2 1 e t a c i
- 9. 6 8 4 3 1 8 7 6 8 9 8 6 l J 7 6 4 51 3 2 0 9 8 o 1 8 2 2 9 p 1 5 3 2 2 2 3 8 6 6 1 e 1 r e
n o 6 3 7 7 u w 4 6 9 8 . J t J s 8 0 2 9 8 7 1 3 l h m 2 2 1 2 1 e g o n u r a o f p r 1 2 4 1 h d 8 3 7 1 l t e M a t 3 2 1 1 1 3 1 2 i 5 a t 8 l n 9 u e 1 c u l q y a 6 9 2 2 4 3 5 5 e r c A s a 1 1 1 . 1 1 1 u s y n n l a a h J e t m n m 5 2 7 8 o o t M 8 1 1 5 m r n f e 1 1 1 2 1 r s e r e b o r m p e s e c 1 r 1 2 1 2 e 8 F 7 2 5 6 D 9 7
. 1 2 8 1 m 9 8 9 o7 y9 1 r9 r1 f 1 a h u n g y y n i u l 1 1 1 1 l r a o J o I. 1 1 n aJ d r )
c < < < < < o u eh d n n l t e d a i p u eJ m3 n r d a 8 i u r e s 9 t s ol 1 n af p t o N e m s n C O m e a ri ( I l si T 9 1 s b f s 4 4 9 1 4 4 9 1 4 4 s a t t A 1 3 3 1 3 3 1 3 3 al o s h 3 T mi n a g S o a wi 4 i v e e b a r 4 r 3 e3
,t w r 3 8 o n e
' 7 n s ob 9 l i m E R
* *7 1 a et e
- t. 4 6 t n a c S A 8 8 8 n a at e A E 9 9 9 T Y 1 I D P S D 1 1 a e w$
. 1 l
I { ) i 1987 were substantially lower than recent baseline years (1983-1986). Temporal patterns at paired stations, (19 vs. 31 and 4 vs. 34) were similar j In 1987, but over all biomass values were depressed September through l I December, in comparison to 1983-1986 (NAI 1988 and photographs in project flin). Laminarla spp. spore 11ngs (mostly L. saccharina, but occasionally
- 4. digitata) settlement on MS panels has been highly variable from year to l
year, but generally, more Luminarla spp. fronds have been present in July, August and September than later in the year (NAI 1987b). Settlement was dense in 1987, especially at Station 19 and Stations 31 and 34 (Table 3.3.4-4). Settlement at Station 4 was slightly higher compared to recent years. The highest mean density compared to past years occurred at Station 19 in 1987; a value similar to that of Station 31 at which densities have historically far exceeded any other station. Station 34 exhibited notably higher abundances throughout 1987 than those recorded at Station 4. l 1 1 1 I l l 259
' ;11l s.
2 1 1 5 0 9 0 2 8 5 5 9 7 8 6 1 8 7 8 0 0 3 8 6 4 6 D. 2 3 2 3 9 7 8 9 9 8 7 5 4 2 0 0 4 5 8 8 6 8 7 9 9 6 S 0 4 3 3 0 2 2 - 0 57 9 2 57 0 1 6 3 2 7 2 8 1 1 7 1 2 1 1 5 3 1 4 1 5 1 2 1 1 M T E t N f 9 1 1 2 3 2 2 3 4 3 4 2 5 4 3 4 2 7 6 3 7 6 1 9 2 6 R A I E 3 2 1 7 0 3 1 3 4 5 0 1 7 2 0 2 1 1 4 2 7 1 1 4 P 1 6 1 1 7 3 9 1 2 8 1 9 5 2 W f 1 A R A - E Y C 1 0 1 6 6 0 7 9 5 4 8 3 1 8 9 0 2 0 0 0 1 5 0 0 1 3 E 3 51 9 3 6 7 1 1 4 2 9 6 4 E D M I T A T W 3 0 5 1 1 4 3 553 6 1 4 9 8 0 3 0 0 0 6 7 6 0 0 3 S E 2 6 2 6 7 0 2 2 0 1 8 4 2 I 1 1 1 A tE l A T 4 0 8 8 4 3 5 9 0 2 3 6 3 4 5 0 9 2 0 0 2 3 0 0 0 1 Y C 1 4 3 8 7 2 1 2 5 6 5 3 B O 1 1 1 5 1 EI A P 8 0 4 5 6 1 6 2 1 5 5 9 9 1 4 0 7 1 0 1 1 0 1 4 0 5 P E 1 6 2 7 1 9 7 1 4 9 5 3 S 1 1 C I D . L l U i O G 0 0 7 4 2 3 7 9 0 4 6 9 2 1 4 0 5 1 0 0 4 5 1 2 5 4 r F U 1 6 3 2 2 3 0 3 4 6 2 2 6 1 5 p A 1 1 1 1 A E C e A r F R o U L f S U 9 2 61 3 0 18 2 2 9 2 3 2 6 5 5 0 6 1 0 7 0 9 7 5 1 5 . e 1 0 2 1 9 4 2 1 2 1 7 1 6 2 1 a b L J 1 1 1 1 t A a t I t n T i e I d g s D f l 0 0 2 8 4 9 - 6 2 6 3 3 8 0 2 0 2 6 i . e U U 3 3 6 1 0 3 d 6 r G 1 6 - 7 2 2 7 1 1 4 1 1 8 p J 1 1 9 E L 1 ) S . g Y y e n L . l ni f 7 Y 0 3 4 0 1 2 l a t - D8 0 0 8 7 6 a h. A 2 1 0 1 8 0 1 2 1 8 3 9 n 1 5 1 9 9 1 3 2 n f 9 f 0 1 N , M 1 5 oh o i g c u s u N T a o r O R c r o O ch f 5 P R 0 4 3 0 9 0 0 4 8 0 2 ot f E P 5 0 0 3 8 0 2 0 7 0 3 0 h . f l U R A 0 1 4 2 d 5 t 0 n8 g8 a9 n9 O C E 1 e1 D a y l n
.E L i r m ne P S R 0 1 2 3 4 6 7 0 1 2 3 4 6 7 0 1 2 3 4 6 7 2 3 4 6 7 r a u u -
S A A 8 8 8 8 8 8 8 8 8 8 8 8 8 8 a u mJ B E 9 9 9 9 9 9 9 9 9 9 9 9 9 9 8 8 8 8 8 8 8 8 8 8 8 8 h ni A Y 1 1 1 1 1 1 1 9 9 9 9 9 9 9 9 9 9 9 9 c a n1 I K 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 c Ji3 R 0 a m A 0 s mE n I I t i o o I B . r mi . L f ct t r A N a A E O ed 3 t = L S I 9 1 4 4 r e>S T 1 3 3 et A w ce p .o r 4 T S, d l sf el 4 t oa g 3 n ci u r i n n 3 o s a s s D cl n E D ei i D n ma L L D m t 8 A A E E I F L E I E I F L E Aa
- pL a I
T R A R A F R R A F R wo F 0 l I o a D t E A E A 1 D F D F *
~.
u$ ll I lll l
l 3.3.5 Selected Benthic Species Seven macrofaunal taxa from the area of'the discharge (nearfield) and from a control area off Rye Ledge (farfield) (Figure 4.1-3) were selected l for intensive monitoring. Three nearfield/farfield ctations pairs were f sampled: intertidal Stations 1MLW and SMLW, 5-m Stations 17 and 35, and 9 to 12-m Stations 19 and 31. Selection of taxa was based on abundance, and/or trophic level (Table 2.3-1). .t l
.1 3.3.5.1 Mytilidm Mytilidae, composed primarily of juvenile #ytilus edu11s, was the most abundant taxon at all three nearfield/farfield station pairs. Nytilus adulis reaches 100 mm in length (Gosner 1978), and is an important prey species for fish, sea stars, lobster, and gastropods. It clings to hard substrate with strong byssal threads, and is an important fouling organism.
The geometric mean density for the entire 1978-1987 study period was highest intertidally, and generally decreased with increasing depth (Table 3.3.5-1), a trend also reported in NAI (1985b). The highest density (geometric mean over all years) was 112,927/m" at intertidal Station 1MLW and the lowest was 1,553/m 2 at Station 19, which has a depth of about 12 m. , Each station in the three nearfield/farfield station pairs was tested separately for annual differences. Significant differences in annual abundance occurred among years for five of the six stations when tested with l a one-way ANOVA (Table 3.3.5-2). The year 1985 had the highest abundance at both 9 to 12-m stations (Stations 19 and 31), but 1985 had nearly the lowest abundance at the 5-m stations (Stations 17 and 35) and for intertidal station l 1MLW using the Wallsr-Duncan comparison test (Table 3.3.5-2). At the 5-m subtidal stations the abundance was at the all time high in 1979 at Station-17, and was also very high in 1984 and 1987 at both 5-m stations. At inter-tidal Station 1 MLW, the highest abundance occurred in 1982. 261
R E 3 1 V O - N 8 3 4 8 80 7 6 8 9 3 5 2 4 5 9 5 5 A 3 1 5 4 1 2 7 5 5 5 3 5 1 8 7 7 4 51 91 5 1 Y E - 2 1 1 2 2 4 6 3 2 4 1 6 1 9 2 53 L 1 7 L 1 A U N N 0 0 8 5 39 6 4 1 1 1 0 7 6 8 5 9 7 . A 4 4 1 0 9 0 7 8 2 0 3 2 0 0 9 1 I 7 4 2 5 8 93 1 9 5 0 0 3 3 1 R 8 1 5 7 3 8 1 1 T 9 6 7
. 1 2 2 D 7 1 1 E 8 L 9 P 1 .
_ M 1 0 3 9 6 7 8 5 4 4 3 5 9 1 8 3 5 3 _ A . 6 < 7 7 6 8 9 5 4 9 4 9 5 9 0 7 3 2 S T 8 3 1 3 4 4 7 2 9 9 5 6 9 7 1 _ R 9 2 1 4 5 4 2 S O
%20 1 3 E P I
C E E 1 1 P S E I 5 30 2 8 9 9 2 5 2 6 7 0 0
- 5 6 5 6 5 1 7 5 5 0 8 4 0 8 5 8 3
_ C L 8 5 1 6 4 35 50 6 4 5 7 2 3 fh82 1 _ I E 9 1 1 1 6 3 1 _ HS 1 3 7 1 _ TA h B 6 5 8 _ E _ B K _ O _ D O 9 1 2 7 0 1 9 5 0 6 3 2 6 9 6 2 9 3 _ E R 4 < 9 6 6 3 4 9 8 1 9 4 7 0 8 1 2 3 _ T B 8 3 1 6 0 88 9 4 4 8 1 9 3 5 C A 9 2 7 6 5 _ E E 1 8 3 3 7 L S 7 7 1 1 E S F 7. _ 0 8 3 5 8 9 8 0 82 3 8 7 5 6 3 2 0 5 5 _ 9 3 2 1 0 3 9 8 7 5 6 2 4 9 8 8 6 7 1 5
) 1 8 9
2 39 9, 5 9 3 2 0 5 7 5 4 _ 'm GH 1 4 0 0 7 1 1 1
/. 0 6 6
~
o0 N R ( E - T 3 8 9 0 87 5 3 0 6 6 8 4 9 2 4 0 2 E 2 3 8 6 3 9 0 7 1 9 6 7 8 4 4 6 5 8 7 C 8 8 1 6 6 1 3 32 4 5 7 6 9 6 7 5 N 7 9 35 3 1 1 1 A 9 1 3 2 D 1 5 4 N 2~ U M B O AR F 3 - 8 - 9 - 0 - 7 - 9 0 1 - 4 0 1 2 E 1 4 3 8 9 5 6 5 8 5 E R TE 8 9 3 7 1 3 - 3 8 2 2 0 6 2 1 5 6 8 4 2 1 B 1 0 3
&EMV 3 1
1 O
'N A
N - 8 - - - 9 - 0 - 9 - 5 2 3 - 9 0 2 3 ENDA 0 8 9 4 4 7 6 6 7 6 2 0 2 9 4 7 9 9 9 5 3 5 7 1 O 1 1 3 I . 0 3 RT 7 1 T S EG 0 U U 5 - - - 4 - 3 - E A 9 9 - 7 8 7 - 8 0 0 0 4 8 7 8 0 3 8 3 0 7 6 G 7 5 8 9 7 3 3 9 5 4
. 9 8 - 3 2 L Y 1 6 A A 1 U M 1 N )
N N r A I a b e 8 - - - 7 - 9 - 5 - 5 7 5 - 2 0 8 y 1 8 7 1 5 0 0 5 7 7 8 83 4 5 3 0 9 1
% 2 2 r
- 9 1 1 1 1 e 5 1 1 p 6
3 1 s 3 e m E WW WW WW i t A L B A T S EE I S 7 5 1 3 7 5 1 3 EE I S 7 5 1 3 9 1 L M E 9 1 9 1 3 T 1 3 I S 1 3 1 3 n e k a t s e a s t t i s a a m u c c s r t i u e o s l i r a l n ri p b t l i t s e u a i p n n r r e c a e e A a a i ci 3 l e l e oh ( X e d a a n l c A e i f d a e y a 9 T h i i l g gb t r a l l o n e - i e s i e t o o c t s t c n r r n r s a y u o t d A A J M N P S a wlS L
3 7 2 8 8 8 F O 7 4 6 . ) 8 8 8 _ 2 a
/. ~
o 5 3 0 N 8 7 8 I Y I . I 7 4 3 9 3 S 8 S 8 8 7 8 N 9 N ._ E 1 O D , S I - D T R 3 7 1 8 6 3 ERO A 7 8 8 8 8 8 P RP
~
t - O E G F R C S 2 6 6 7 4 _ 6 N 8 8 8 8 8 _ 8 A E E R D P _. T L I E T 7.
)
S L 1 5 9 5 4 1 A U 8 8 7 8 8 8
+ G M lx K O
GO 0 4 5 6 5 5 DR I B 8 8 8 8 8 8 A E t S 1 4 T 8 3 0 2 2 7 7 8 8 8 8 8 R O 7. F 8 9 2 4 1 2
- 1 9 8 8 1 8 8 S 7 -
8 J GH t t E U Y O R S S S G H M M e M N T
- m O 5 4 0 3 8 5 7 8 7 M 8 3 5 9 0 3 0 8 3 6 A 7 F 9 8 5 4 1 2 2 6 4 1 E 1 1 1 .
C N t AG I R 593 506 57 3 909 991 t 81 9 7 41 235 832 J F 832 235 01 2 831 6 6. %. 741 393 796 708 t V D S 775 1 90 59 4 089 786 427 450 764 662 E S 944 31 5 1 23 22 1 12 34 F L 1 O P M S A I S S f 909 583 90 9 583 909 583 662 583 909 Y S d 88 45 8 8 45 88 45 56 45 88 L E ' , A I N C A E P Y S FN A OO MC I srl srl sr l srl srl srl srl srl rl
- I ET roa roa ro ar a roa roaart roa roaartroa roa ro EHT CA RI art ero art ero er t
o art ero ero art ero ero ero art art ero WFE UR OA YET YET YE T YET YET YET YET YET YET F B SV O D S E T T - N N t W N L C AO L u L L 7 U I TI M M M M 5 7 5 9 S 1 ST I S I S 1 3 1 3 1 E E R S
. a 2 t
- a s 5 c u i l 3 r l a b i t 3 u p a a r a c e i l l a e E e a d ns B S o s f i ei A E h l i ga T I t l a s
r or C i e e t e E P e s t nn P m u a s oi S A M J A P wg II I
3 5 8 3 8 8 7 8 5 3 9 8 _ 8 8 7 7 0 0 0 2 8 8 8 8 4 8 6 9 _ S 8 7 8 7 N O S I R 9 1 5 3 6 A 7 8 8 8 8 P t a C 7 2 2 2 7 E 8 8 8 8 8 L P I T L 1 6 6 1 0 U 8 8 8 8 8 H 8 7 3 7 1 7 8 8 8 8 6 4 7 4 4 8 8 8 8 8 2 9 4 5 5 8 7 8 8 8 S S S M M N
- 7 1 "8 7 5 "7
- 6 0 9 5 3 8 6 3 F 0, 1 1 1 2 2 2 4 3 1 1
268 448 1 56 1 90 1 1 1 820 279 145 921 055 785 641 932 449 662 932 I S 472 651 337 179 203 s S 1 68 34 875 720 720 e 1 1 1 45 12 270 225 t 1 a c i l f 909 909 909 p 583 909 583 909 909 e d 88 88 88 45 88 45 88 88 ) r 1 3 0 X 0 FH t 0 OC ss I rl rl rl rl rl de > rl rl rl ) ET A roa art roa art roa art roa roa roa roa roa i ot 1 art art art art rn RI UR ero YET ero ero YET YET ero ero YET YET ero YET ero YET art ero eo) 02 OA YET ps50 SV 1 gr na0 i0.>0
) i p p0 d
e u AO TI N 9 1 N L M N L M 7 l pn mep o>2(t 5 9 1 a n ST 1 3 1 5 1 3 seI 5n i t 1 3 lt 0.c a n 3pn0ii o 4i a1 f s C s t c i 9 lit ny E u = u f n gl t os nmiaih ncsg
. ri rngi 2 t s - nn aaif yh 5 ee ecsil ci yn nhy 3 oh e ut ggr l c a hDoiie 3 S ya d c nshv E gb i ar E I ne l ee====
L C oo i l rlS* *
- B E rr t oaM *
- A P t d y T S S M FM
{ e e>
)
i The Mytilidae. collected usually ranged from less than 1 mm to 30 mm in length, and many of the smallest mytilids had settled on macroalgae rather ; than on the bottom or hard substrate,'a pattern also observed by other l l .I investigators (Bayne 1965; Suchanek 1978). Information from surface fouling ( panels suggests that primary or. secondary settlement _ takes place throughout the year, but'is heaviest from June through October (NAI 1985b). ~The'overall I mean length of intertidal mytilids (3,2 mm) was slightly larger than subtidal ( mytilids, (2.4 mm) (Table l3.3.5-3), even though intertidal population den-f sities were much higher than subtida1' densities. Mytilid lengths showed no significant differences between nearfield and farfield station pairs when tested with a two-way ANOVA (NAI 1987b: Table 3.3.5-4). Yearly differences in mean length for each of the nearfield/farfield station pairs were not ; significant (NAI 1987b: Tabic 3.3.5-4). In 1987, the lengths at the inter-tidal station pair were about average even though the density had increased; at subtidal station pairs the mean lengths in 1987 were below average, and ) I densities decreased at three of the four stations (Tables 3.3.5-1, 3), indicating below average growth and recruitment. The level of mytilid recruitment is indicated by the abundance on short term fouling panels set 3 m below the surface'at Stations 19 and 31 and exposed for one month intervals from 1978 through 1987. Recruitment was the highest ever at Station 31 in 1979, with a yearly average of 4687 spat per' panel, and again in 1981 with 4082 spat per panel (Appendix Table 3.3.4'-1). During the next two years, 1982 and 1983, recruitment was the lowest with just under 60 individuals per panel. Abundance in 1987 was below average at Station 19, but at Station 31, the 1987 abundance was the highest in six years, with 1187 spat per pant 1, Over 90% of the mytilids collected from panels at Stations.19 and 31 in 1987 were 3 mm or less in length (NAI 1988: Appendix Table 9-8). Mytilid lengths at Stations 19 and 31 ranged from <1 mm to 20 mm in 1987 (NAI 1988: Appendix Table 9-7), about the same as previous years. 265
l j,I 36 21 21 11 11 64 34 23 Y L I - - 00 00 00 00 00 00 00 00 L A . 7 C U 7 l 8 8 9 16 85 11 93 80 93 76 77 e9 l 1 N A 1 A - - 34 3s 33 12 12 14 45 11 I R , E I 1 TT R DO I L E P I 66
- f. 7 12 12 13 55 32 32 P R C - - 02 00 00 00 00 00 00 00 M 6 A 2 8 S k 9 I 1 M 31 41 80 57 31 72 72 55 S L A E E E - - 73 44 24 22 24 76 45 11 I S M 1 C A E B P
S K 0 1 40 22 21 21 21 35 33 46 C 0 I I R C 4- 01 00 00 00 00 00 00 00 M 8 5 f A f 8 B DSE 9 1 N A 9 51 55 60 44 45 03 38 75 E 0 - 70 44 23 22 23 56 55 22 D .7 E D 1 1 1 I 8 C9 E 1 L 5 89 21 11 12 11 26 22 32 E H I r S G C 1 - 00 00 00 00 00 00 00 00 e U 4 b R 0 8 m O t i 9 e F H 1 N 99 87 47 79 81 11 09 96 77 v
) T A o E 68 75 43 22 23 E2 46 44 11 N I 2 M C 8 d
( 9 n 1 L a A t 68 74 22 22 11 26 33 53 , V N R t I 11 t t i C 00 03 00 00 00 00 00 00 00 s r E F u a T 3 g N S 8 e I N 9 N u y O 1 A 75 44 37 52 11 39 32 22 83 A E I E t 78 51 43 43 22 21 3 6'. 55 12 , a C T M 1 y h N A a t E T M D I S n F n i N ED 35 35 22 11 11 12 35 32 32 i I d DT C 00 00 00 00 00 00 00 00 00 d e C C e r 2'
%E 8 r u
u s 5 E 9 s a 9 S 1 N 76 03 35 78 98 4 C 07 46 87 a e A f. E M T A M E 67 45 33 22 11 22 85 44 11 e m s m - T s l R l a OEB I a u A u d D 34 24 d i 01 01 v
) 11 11 22 11 11 i V I nD C 00 00 00 00 00 00 00 00 00 v i aM L i d L d n t
A n i H O I R i f TA G E N 08 55 18 12 34 17 19 91 99 l o N , V A l T O E 77 56 43 33 22 22 65 45 11 a r . ESU M f e b N G o m A U u s n EA I N h t l O NN NN NN g a L Y I LL LL LL n t A A T MM 75 75 MM 75 91 MM 91 91 e o UM E A 1S 13 13 1S 13 13 1S 13 13 l t S N T I S d A I e e h t t c 3 5 t a a a n e i s s n e f o m l l o c e 3 a e c i c i u t a l e e e s c o h s e e a d a a a a u n s l c n 3 A o c i f d d d a l e i y s a = o X h i i i i i l l g m g u b n A r E B T t r i b p u t e a s s l i t l i t l i t l e p c a i t o r n n e n t e o o o r r r N A E
= -
A m r s a y y y u l o i t t d M T A A J M M M M P S a b ooe t lll
( }
- 3.3.5.2 Nucella lapillus Nucella lapillus reaches 51 mm in length (Abbott 1974), and is an abundant intertidal gastropod and an important predator, particularly on mytilid spat. Significant differences in abundance between stations were found between intertidal Stations 1MLW and SMLW from 1982 through 1986 (NAI 1987b
- Table 3.3.5-2). The overall abundance at Station 1MLW was more than double the overall abundance at Station 5MLW (Table 3.3.5-1). Very highly significant differences among the years 1978 through 1987 were found for Station 1MLW with 1984 having the highest abundance and 1987 and 1982 having the lowest abundances (Table 3.3.5-2). Farfield Station SMLW was sampled from 1982-1987, and no significant differences were found among years (Table l 3.3.5-2).
Large numbers of small Nucella occurred in August or September, indicating recruitment occurred at that time (NAI 1985b). Larger individuals l (10-25 mm) were collected in most months, but disappeared from November 1983 through June 1984. Previous studies have shown adult snails to be active only from May through October, retreating into crevices in the winter; while juveniles (2-5 mm) are more evenly dispersed throughout the year (Menge 1978). The overall mean length for the 1982 through 1987 study period was 6.1 mm i 0.2 at Station 1MLW, and 5.9 mm i 0.2 at the farfield control (Table 3.3.5-3). The average yearly length ranged from 3.3 mm at Station 1MLW in i 1983 to an unusually large 11.9 mm at Station 1MLW in 1987. No significant differences in the yearly mean length were found between stations or among years (NAI 1987b: Table 3.3.5-4), 3.3.5.3 Asteriidae The Asteriidae collected are juveniles, too young to be assigned to genera. Two species of both Asterfas and Aeptasterfas can occur within the study aren (Gosner 1978). Asteriidae are important predators on bivalves, particularly on the recently-settled stages, as well as other molluscs and I barnacles (Gosner 1978). j f , 267 l 1
Significant differences in annual abundances were found among years and between stations at subtidal Stations 17 sud 35, sampled from 1982 through 1986 (NAI 1987b: Table 3.3.5-2). Station 17 had higher geometric mean densities during all years and the overall average density was over three times higher than at Station 35 (Table 3.3.5-1). Highly significant differences were found among years at both Station 17 and 35 when tested with one-way ANOVA (Table 3.3.5-2). The yearly trend was very similar at both stations: highest abundances occurred in 1982, 1985 and 1987 and lowest abundances occurred in 1983, 1984 and 1986 at both stations (Tables 3.3.5-1 and 2). A successful set of juvenile Aster 11dae occurred in August of 1982 (NAI 1983a), and very little recruitment occurred in 1983 or 1984. In 1985 and 1987 annual densities were relatively high, indicating successful recruit-ment. Spatial and temporal changes in abundance and length seem to be related to the recruitment success of each year's cohort (NAI 1985b). The overall average length at Station 17 was 5.5 mm i 0.2, and at Station 35 it was 6.5 mm 1 0.4 (Table 3.3.5-3). Yearly mean length of sea stars collected at Station 35 was usually greater than Station 17, and the two stations were significantly different according to the results of a'two-way ANOVA (NAI 1987b: Table 3.3.5-4). Likewise, the mean seasonal length from 1982 through 1987 as compared with a paired t test, showed interstation differences were ' highly significant (N = 18 pairs, t = -4.08, probability of a greater t = 0.008), with larger sea stars occurring at Station 35. The average yearly length ranged from 3.1 mm in 1987 to 7.8 mm in 1984 at Station 17, and from
.4.6 mm in 1987 to 13.1 mm in 1986 at Station 35 (Table 3.3.5-3).
A few recently-settled Asteriidae were collected on short term surface fouling panels from 1978 through 1987, and only occurred from July through September. All years except 1980 and 1981 had very low densities averaging less than one per panel per year (Appendix Table 3.3.4-1). i ( 268
(, ~- p i 3.3.5.4 Pontonenela inermis , Pontogenela inermis (maximum' length,-11 mm) is a pelagic, cold water amphipod (Bousfield 1973), and a dominant species in benthic and ; macrozooplankton collections (NAI 1985b). It clings to submerged plants and
.signe from the low r intertidal to depths greater than 10 m (Bousfield 1973). J Population densitie. were remarkably consistent from 1978-1986, and no' significant differences were found among years with two-way'ANOVAs (NAI 1987b: Table 3.3.5-2). Likewise, when a one-way ANOVA was used to test for-differences among' years, including 1987 data,'no significant difference was .)
found for either station (Table 3.3.5-2). However, interstation differences were significant, and the.overall geometric mean abundance from 1978-1987.was 1.5 times higher at Station 19 than at Station 31 (Table 3.3.5-1). Ovigorous and brooding females were collected in low. numbers from January through September (NAI 1985b). ~ Recruitment, as indicated.by a sharp- ] increase in density and increased numbers in the 1 to 3-mm size class, took place between May and July. In fall and winter, abundance decreased, but average size increased as the population grew'(NAI 1985b). The overall mean-length for the 1982-1987 study period was 4.9 mm (95% confidence interval = i 0.1) at Station 19 and 5.1 mm i 0.1 at Station 31 (Table 3.3.5-3). No l significant difference in mean lengths was found between' stations (NAI-1987b: Table 3.3.5-4). The average yearly length ranged from 4.4 mm at Station 19 in 1982 to 5.8 mm at Station 31 in 1985, with no significant difference among years (NAI 1987b: Tables 3.3.5-3 and 4). The 1987 data did not change the range of the annual mean lengths (Table 3.3.5-3). i Pontogenela inermis was common on short term fouling panels, at Stations 19 and 31 from 1979 through 1983, but numbers decreased sharply ; in 1984, 1986 and 1987 (no samples in 1985). Peak abundance usually occurred l from April through June, and annual mean abundances were highest in 1981 (Appendix Table 3.3.4-1). By 1987 the average yearly abundance had declined to zero. l
\
2s9
3.3.5.5 Jassa falcata Jassa falcata (maximum length 9 mm) is a tube-building amphipod, and a dominaat fouling organism on hard substrates in areas with strong tidal and wave currents (Bousfield 1973). It is a suspension feeder and also preys on small crustaceans. Very highly significant differences in yearly abund-ance (1978-1987) were found for subtidal Station 17, but not for Station 35. At Station 17 yearly abundance was low from 1978-1980, peaked in 1981 and 1982, and declined to all time lows in 1983 and 1984 From 1985-1987 popu-lations were rebuilding, and yearly abundance was above average. Station 35 had a higher population density of Jassa than Station 17 during all years except 1985-1987. The mean geometric density at Station 35 for the 1982 through 1986 study period was 2110/m 2 and fluctuated between 809/m8 in 1987 2 and 5307/m in 1982 (Table 3.3.5-1). Most lifestages of Jassa were collected at Station 17 and 35, ranging frcm gravid females to newly-hatched young (NAI 1985b). Gravid females were most abundant from April to November, and newly-recruited juveniles measuring 1-2 mm were most abundant in July, and were collected during the remainder of the year (NAI 1985b). The overall average length for the 1982-1987 study period was 4.1 mm at Station 17 and 3.8 mm at Station 35; interstation differences were not significant (NAI 1987b: Tables 3.3.5-3,4. Average yearly lengths ranged from 3.3 mm in 1982 at Station 17 to 4.5 mm in 1985 at Stations 17 and 35 (Table 3.3.5-3), i Densities on short term fouling panels, exposed for one-month intervals, from 1978 through 1987 give an indication of recruitment or settlement activity. From 1978-1987, substantial numbers of young began appearing in July and continued to settle through October (NA1 198Sb). Record high monthly densities occurred at Station 31 in 1987 from July through October, peaking in September with 541 Individuals per panel j (Appendix Table 3.3.4-1). Mytilid spat densities were also high on short term panels at Station 31 in 1987 (Appendix Table 3.3.4-1). q ( 270
3.3.5.6 Ampithoe rubricata Ampithoo rubricata (maximum length, 14-20 mm) is an amphi-Atlantic ) boreal amphipod which constructs a nest among macroalgae (fucoids) and in mussel beds (Bousfield 1973). Average yearly densities have dropped steadily and significantly during the study period (NAI 1987b: Tables 3.3.5-1, 2), and populations at both Stations 1HLW and 5MLW had virtually disappeared by 1986. Significant differences were found between stations, with Station 1MLW having much higher densities than the farfield Station SMLW (NAI 1987b: Table 3.3.5-2). During the extended study period between 1978 and 1987, the 8 3,cometric mean yearly density declined significantly, ranging from 545/m in 1978 to 0/m' in 1987 (Table 3.3.5-1). Ampfthoe rubricato is a boreal species near its southern zoogeographic limit, Long Island Sound (Bousfield 1973), and it may have been affected by increasing annual temperatures from 1980 through 1986 (Table 3.1.1-1). Ovigorous and brooding females were rare, but were occasionally collected from April through September (NAI 1985b). The largest numbers of small (1-3 mm) individuals were collected from April through September, suggesting recruitment occurred during this time period. In 1983 and 1984, recruitment appeared depressed, accounting for both lower overall densities and larger mean size (NAI 1985b), and the trend continued through 1987. The overall mean length for the 1982 through 1987 study period was 7.0 mm at Station 1MLW, and 7.8 mm'at Station 5MLW (Table 3.3.5-3), and no significant difference in the average yearly length was found between stations (NAI 1987b: Table 3.3.5-4). The average yearly length ranged from 6.7 mm at Station 1MLW in 1982, when young were present, to 10.9 mm at Station 1MLW in 1986, when only a few Inrge specimens were collect ed (Table 3.3.5-3). When mean seasonal lengths were compared with a paired t test, interstation ' differences were not significant (n=6 pairs, t=0.21, probability of a greater t=0.843). I 271
3.3.5.7 Stronnylocentrotus droebachiensis Strongylo6entrotus droebachlensis, the green sea urchin, reaches 75 mm in diameter, and is an important prey species for lobster, cod and other fish, and sea stars (Gosner 1978). It is an omnivore, but prefers Lam /narla saccharina over other common algal species (Larson et al. 1980; Mann et al. 1984). When the macroalgal supply is depleted, it will prey on Nytilus edu11s (Briscoe and Sehens 1988). It is subject to population. explosions which can denude large areas of macroalgae, leaving barren rock (Breen and Mann 1976). No significant differences were found between Stations 19 and 31 (NAI 1987b: Table 3.3.5-2) for the 1978-1987 study period. No significant differences were found among years at either station, when tested with a one-way ANOVA (Table 3.3.5-2). The geometric mean yearly population density over all years at nearfield Station 19 was 75/m', and at farfield Station 31, it was 45/m 2. Yearly geometric mean density ranged from 2 15/m in 1983 at 281/m' in 1981 at Station 19 (Table 3.3.5-1). Most of the individuals collected subtidally were juvenile, mes-suring less than 3 mm in diameter, and recruitment of newly-settled young usually occurred in August and September (NAI 1985b). The average length for the 1982 through 1987 study period was 1.9 mm at both stations (Table 3.3.5-3). Neither yearly nor interstation differences in average length were I significant (NAI 1987b: Table 3.3.5-4). The average yearly length ranged from 1.5 mm at both Stations in 1986 to 2.7 mm at Station 19 in 1985. I I In order to account for adult individuals which were too large to be collected in the destructive program, urchins were enumerated in the subtidal transect program done by SCUBA divers. No more than 13 large (> 10 mm) sea urchins por year were counted in three years of sampling (NAI 1986a, 1987a, 1988). < 4 ( Recently-settled sea urchins occurred occasionally in monthly . samples from short term fouling panels set at Stetions 19 and 31 during the ( 10 year study period (Appendix Table 3.3.4-1). Most were collected at 272 >
Station 19 from June through September 1981, when the yearly density averaged 1 per panel. The yearly density for all other years was less than one. y specimen per panel per year. The geometric mean yearly density from bottom samples reached an all-time high in 1981, at Station 19 (Table 3.3.5-1), and is a reflection of successful recruitment of young-of-the-year, i 1 l l l
~
l l i I l 1 8 i 273 )
+ 't 3.3.6 Ep1 benthic Crustacea l-l 3.3.'6.1 American Lobsters ' Ulomarus americanus)
Lobster Larvae Lobster larvae'have been-relatively rare during'the ten-year study period at. Station P2. Mean density 'of lobster larvae at the intake site was highest in 1978 (1.45/1000 m')'and lowest in 1980'(0.46/1000 m')-(Table 3.3.6-1). The mean number of lobster' larvae caught in 1987 st Station P2 was slightly below the average of the other years sampled but similar to 1986. The maximum abundance of lobster larvae usually occurred in July-September (Figure 3.3.6-1). During 1987 lobster larvae first appeared in early-June at Station P2 which was earlier than most other sampling years and peaked in mid-July.
~
The farfield sampling site, Station P7, was sampled beginning in 1982. The density of lobster larvae collected at this station fell from 1.32/1000 m' in 1982 to the lowest 1cvel in 1984 and' increased again in 1985 and 1986 to the highest levels recorded in this' study (Table 3.3.6-1). Abundances in 1987 were was similar to the 1986 levels. Abundances were always higher at Station P7 than P2; this difference was most pronounced in 1985 and 1986, when abundances at Station P7 were more thon twice those at Station P2. Larvae first appeared at Station P7 in late June during 1987. In 1986, a third station, PS, was added to the sampling regime, located in the vicinity of the intake structure. This station was sampled only from July 1 through October 14, 1986. Larval abundances were inter-mediate between abundances at Station P2 and P7 (Table 3.3.6-1). Larvae were observed from early July through mid-September matching the pattern at the other two stations in 1986 (NAI 1987). l 274
I I TABLE 3.3.6-1. PERCENT COMPOSITION OF LOBSTER LARVAE STAGES AT STATIONS P2, j PS AND P7, 1978-1987. SEABROOK BASELINE REPORT, 1987. TOTAL % NO. OF MEAN PERCENT PER STAGE OF LARVAE NO. OF i STA- STAGES COL- LARVAE } YEAR TION" I II III IV' I AND IV LECTED COLLECTED 1978 P2 10.1 0.0 0.6 89.3 99.4 169 1.45 l ) p7 .. .. .. .. .. NS NS f i 1979 P2 70.8 2.5 1.7 25.0 95.8 120 1.18 i l P7 -- -- -- -- -- NS NS 1980 P2 86.5 0.0 0.0 13.5 100.0 57 0.46 P7 -- -- -- -- -- NS NS 1981 P2 31.8 1.9 6.5 59.8 91.6 107 0.86 py .. .. .. .. .. NS NS 1982 P2 3.2 0.0 0.0 96.8 100.0 161 1.17 P7 3.8 0.0 0.5 95.6 99.4 185 1.32 1 1983 P2 41.4 0.8 4.9 52.9 94.3 115 0.79 3 P7 47.5 0.6 3.5 48.4 95.9 162 1.10 1984 P2 14.6 11.5 21.8 52.1 66.7 79 0.57 P7 37.2 1.0 2.8 59.0 96.2 101 0.73 1985 P2 1.5 2.9 2.9 92.6 94.1 68 0.85 l P7 7.0 2.1 2.1 88.8 95.0 143 1.91 1986 P2 -- -- 1.4 98.6 98.6 69 0.84 P5 3.5 -- -- 96.5 100.0 102 1.79 P7 21.6 -- -- 78.4 100.0 156 2.01 1987 P2 13.0 -- 1.4 85.5 98.5 69 0.92 P7 7.5 -- -- 92.5 100.0 146 1.94 8
= Station P5 sampled from July 1 through October 14, 1986 only.
= X/1000 m 8 NS = Not sampled 275
2l Pl
. 4 nc o
_ ia _ t t _ . 3 T aa C td S _ 2 O tN
- 1 a(
e l a v7 4 r8 a9 l 1
. 3 P rd E en S t a 2 s
- ..1 bl oa1 l v l
. 4 f e ot
- ) i i'* . 3 me g G
;. i - U 0 n
. 2 A
- 0 e 0di
. 1 il
. 1
/.
l oo N c l.:
';i . 4 (
;.i.:1! %
. ! ; . } .* e5 3 L c9
.!:.I '
U n
.::!: 5 adb
!.: *:: J d n g
1; . 2 na 1.' u
. I ..* b n 5
1 aa
* :- :. : .l:" ,
)
N 7 k 4 1 A E g g ,*.\., +' 3 3 x P
,, / N (
/ U
. 2 J g
. o l
. l l -
6
. a l1 n
/N 4 '
a e7 m8 9 Y y1 r 3 A l - M k8 e7 2 e9 W1 2 0 8 6 4 2 0 1 1 0 0 o a a 1 6 3 3 e uaz*OzDm< $ E OOa s r u g i F N*o l ,f! !
l Historically, Stage I and IV larvae have dominated the collections at both Stations P2 and P7, with few Stage II or III larvae collected (Table 3.3.6-1). Stage I larvae dominated the collections in 1979 and 1980, while Stage IV larvae dominated the collections in all other years. Stage II and III larvae collectively constituted 7% or less of the larvae collected except in 1984, when they made up 33% of the total abundance at Station P2, In 1983 and 1985, the majority of lobster larvae were Stages I and IV at Stations P2 l and P7 (Table 3.3.6-1). During 1986, the pattern at Stations PS and P7 was ) similar to previous years. At Station P2, only Stages III and IV were collected and the overwhelming majority of larvae were Stage IV. In 1987, Stage IV larvae dominated the collection at both stations with few Stage I larvan also at each station; a few Stage III larvae were collected only at Station P2. No Stage II larvae were collected in 1987. Stage I larvae usually appeared at Station P2 during July with large peaks also occurring in June in 1980 and 1983. Peak abundance of Stage IV larvae varied in occurrence between July and August (NAI 1985b). Stage I larvae first appeared in 1985 in late May at Station P7 (NAI 1986). Stage IV larvae were observed in late July at Stations P2 and P7. Stage IV larvae appeared at all stations and dominated the collections in 1986. Stage I larvan were observed at Station P2 in early June and early July at P5; however, collections did not begin until July at Station P5. At all three stations, Stage IV larvae were first observed in mid-July. During 1987, Stage I larvae appeared in early June and late June at Stations P2 (Figure 3.3.6-1) and P7 respectively. Stage IV larvae occurred in early July at both stations while Stage III larvae were collected in early July at Station P2 only (NAI 1988). Trends in the occurrence of lobster larvac in this study have generally agreed with other lobster larvae studies in New England (Sherman and Lewis 1967; Lund and Stewart 1970). An extensive review of New England lobster larvan studies (Fogarty and Lawton 1983) indicated that the period of peak abundance in the region coincided with that observed off New Ilampshire 277 l ! 1
waters, as described by this' study. Also, the high predominance of Stage I and Stage IV larvae among years in this study has been shown to vary from year to year in other New England studies'(Fogarty and Lawton 1983). Abundances and occurence of lobster larvae in inshore' areas have been associated with wind direction. Grabe'et al. (1983) reported that 67% of Stage IV larvae were collected off the New Hampshire. coast when winds were on- or along- shore. Thermal differences between air and land masses, com-bined w.ith predominantly light westerly summer winds, produced onshore winds during the day and offshore winds at night. In addition, hydrographic studies in.the Hampton/Seabrook area indicated a net drift northward or. southward along the New Hampshire coastline. Combined, these two actions suggested that lobster. larvae were moved by.nontidal water mass movements into New Hampshire waters, and were then transported onshore by winds. A synthesis of lobster larvae distribution studies.by Harding et al.'(1983) supports this hypothesis. They noted that lobster landings for all regions neighboring on the Gulf of Maine have been very similar since the mid-1940s. They interpret this to indicate a single lobster stock with common recruitment. They further concluded that warm southwestern waters of the Gulf of Maine and Georges Bank supply the Maine coast and adjoining areas with advanced larval stages, evidenced by a preponderance of Stage IV larvae in the cooler surface waters from southwestern Nova Scotia to Hampton, New Hampshire. This may explain the abundance of Stage IV lobster larvae in the f I present study. A recent examination of hydrographic drift studies (Harding and Trites 1988) also supports the theory of lobster larvae dispersion into the region through current transport. ! Adults l I Adult lobsters (legal and sublegal sizes combined) have been ! collected in the vicinity of the discharge site (L1) from 1974 to 1987 (Table 3.3.6-2). During that period, the highest monthly catch usually occurred 278 l i
I ) a l TABLE 3 3.6-2.
SUMMARY
OF TOTAL LOBSTER CATCH PER TRIP EFFORT , BY. f MONTH AND YEAR, AT THE DISCHARGE SITE (4) FROM 1974 THROUGH 1987. SEABROOK BASELINE REPORT, 1987. l MONTH YEARLY YEAR JUN JUL AUG' SEP OCT NOV AVERAGE l . 1974 41.7 51.2 73.6 103.0 78.6 59.7 68.0 1975 .41.1 42.5 73.9 74.0 71.6 55.2 59.7 1976 35.0 40.7 68.6 69.1 63.7 48.0 54.2 1977 45.8 32.3 63.5 67.3 54.5 61.1 53.7 1978 49.7 34.8 63.4 86.4 79.1 65.5 63.2 1979 54.1 57.6 61.5 62.8 69.9 58.8 61.4 ; 1980 32.2 30.2 70.3 59.7 41.3 43.4 46.2 1981 38.1 42.5 80.2 94.3 65.6 59.3 63.3 1982 35.7 52.3 83.9 71.7 88.8 79.1 68.6 1983 49.2 39.9 89.3 128.2 96.3 29.6 72.1 1984 49.9 28.2 72.1 117.9 146.6 140.5 92.5 1985 25.3 45.2 81.3 121.3 131.2 130.4 89.1' 1986 32.4 37.5 75.0 86.9 80.5 99.7 68.7 1987 39.5 26.3 33.3 57.2 83.2 48.2 46.0 MORTHLY AVERAGE 40.7 40.1 70.7 85.7 82.2 69.9 a Catch per trip effort = total catch from 15 traps per trip. l 279 l
- _ - - - _ - i
/
from August through October. Monthly catch was highest in September during 1987. However, in 1980 the. greatest catch was in August; in 1979,'1982, 1984, and 1985, in October; and in 1986, November. June or July have had the lowest monthly catches (Table 3.3.6-3). Data from 1945 to 1973 reported by the New England Fishery Management Council.(1983) for the Haine lobster. fishery also. indicate August, September and October as peak months in lobster abundance. Average yearly catches per fifteen-trap trips at the discharge station ranged from 46.2 in 1980 to 92.5 in 1984 (Table 3.3.6-2). Lobster catch abundance was also high in 1985 (89.1), but dropped to average levels in 1986 (68.7). The average yearly catch for 1987 was 48.0 per fifteen-trap trip, the lowest average since 1980. Results of one-way ANOVAs of lobster catch for years (1982-1987) and months at the discharge site indicated significant differences among months but not for years (Tabic 3.3.6-3). Multiple comparisons among months also indicated August, September, October and November differed from catch during June and July. Among stations, lobster catch was significantly greater at the farfield station (L7) than at the discharge site (L1) (Table 3.3.6-4). The pattern of peak monthly abundances and the greater abundance of lobster catch at the farfield station is consistent throughout the study since sampling at the that station was begun in 1982. Adult lobster abundances have been related to seawater temperature. McLeese and Wilder (1958), Dow (1969) and Flowers and Salla (1972) have I i examined this relationship. In the Hampton/Seabrook study area, continuous bottom temperature monitoring (1978-1984) at Station ID, near the discharge area, was compared to monthly mean lobster catch. A relationship between ' bottom water temperature and lobster catch was establist.ed at the discharge ; station (NAI 1985b). During June, catch declined as bottom water temperature i increased; however, this was probably caused by the onset of molting which j would reduce the catchability of lobsters. Peak catch of adult lobsters j usually occurred after bottom water temperatures reached approximately 10'C and lobsters had molted to legal size (NAI 1985b). As bottom temperatures cooled, catch declined in November, perhaps reflecting seasonal inshore '1 movement patterns (Ennis 1984) or decreased activity level. Lobsters l 280 4
TABLE 3.3.6-3. RESULTS OF ONE-WAY ANOVA AT THE DISCHARGE SITE FOR IDBSTER (N. ANERICANUS), JONAH CRAB (C. BOREALIS) AND ROCK CRAB C. IRRORATUS). SEABROOK BASELINE REPORT, 1987. SOURCE OF MULTIPLE SPECIES VARIATION df ss F-VALUE COMPARISONS 1
~
Lobster Year 12 14011.66 1.62" Error 65 46975.38 l Total 77 60987.04 Month 5 26287.64 10.91*** 9 10 11 8 6 7 Error 72 34699.40 ! Total 77 60987.04 ! Jonah Crab Year 5 405.95 1.70" Error 30 1428.89 Total 35 1834.84 Month 5 892.45 5.68*** 8 9 7 11 10 6 Error 30 942.38 Total 35 1834.83 Rock Crab Year 5 60.99 6.67*** 85 86 84 87 83 82 I Error 30 54.89 Total 35 115.88 Month 5 28.60 1.97" Error 30 87.29 Total 35 115.89 "b
= Not Significant -(p>0.05)
* = significant (0.052p>0.01)
** - highly significant (0.012p>0.001)
*** = very highly significant (p50.001) 281
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ l
TABLE 3.3.6-4. PAIRED t-TEST COMPARISONS OF Tile DISCIIARGE SITE (L1) AND Tile FARFIELD STATION (L7) FOR LOBSTER (R. ANERICANUS), JONAH CRAB (C. BOREALIS) AND ROCK CRAB (C. IRRORATUS). l SEABROOK BASELINE REPORT, 1987. CATCH /15 TRAPS i- MEAN SIGNIFICANT l SPECIES L1 L7 DIFFERENCE n t DIFFERENCES Lobster 46.0 70.1 18.59 36 4.43*** L7 > L1 Rock Crab 10.7 10.4 0.85 36 3.76*** L1 > L7 Jonah Crab 11.2 11.5 0.18 36 0.24NS 1 NS = Not Significant; *** p 5 0.001 l l l typically show a seasonal migration pattern which is thought to maintain the population at the highest local water temperature (Campbell 1986). It is unenrtain whether New Hampshire lobsters undergo seasonal migrations (NHFG 1974). Although the relationship between lobster catch and bottom water temperature has been shown to be significant for some months, the combined effects of molting and other factors such as food availability probably interact, affecting lobster catchability and its relationship to bottom temperature (NAI 1975b). Further, the New ilampshire Fish and Game Department conducted similar studies off the New Hampshire coast from 1971 through 1974 and concluded that bottom water temperature did affect lobster catch, but was influenced by other factors as well (NHFG 1974). Low catches of lobsters in 1987 may be temperature related. Bottom water temperatures at Station P2 were 1 to 3*C lower from July through October than the overall mean temperature (See Figure 3.1.1-1). Also, benthic invertebrate abundances and numbers of taxa at Stations 17 and 19 in the vicinity of the discharge site were lower than previous years (See Figure 3.3.3-2) perhaps further indicating the effect of cooler bottom water temperatures. 282
Catc:i per effort of legal-sized lobsters at the discharge station averaged from 7 to 10 individuals per fifteen-trap trip from 1975 through 1986 (Appendix Table 3.3.6-1), llowever, in 1987, this declined to three individuals per fifteen-trap trip. The catch of legal-sized lobsters consti-tuted approximately 12% of the total catch during 1975-1981, but decreased slightly to approximately 10-11% of the total catch during 1982 and 1983. In 1984 despite having the highest yearly mean catches, the legal-sized lobster catch at the discharge, declined to approximately 7% of the total catch l (Appendix Table 3.3.6-1; Figure 3.3.6-2). Legal-sized lobster catch increased slightly to 7.2 (10%) in 1986. In 1987, 6.7% of the lo!' ster catch was of Icgal size, comparable to 1984 and 1985 catches. Iloweve r , the total catch of lobsters in 1987 was the lowest yearly average since 1980 (Tabic 3.3.6-2). In 1984, an increase in the legal size limit for lobsters from 3-1/8" (79.2 mm) to 3-3/16" (80.9 mm) was enacted. Because of the change in the law, a number of adults which would have been legal-sized under the old sizn limit, were retained in the sublegal size class during 1984 and 1985, adding to those lobsters molting to legal-sized lobsters in 1986. Annual size-class distributions (Figure 3.3.6-3) indicate that the l abundances of lobsters in the 42-54 and 54-67 mm size classes have steadily declined since 1975, while catches in size class 67-79 mm (2-5/8" to 3-1/8") have increased through 1985. Size classes above 79 mm have had low catch l abundances, indicating that commercial fishing in the study area quickly removed the majority of lobsters as they attained minimum legal size. The increase in catch abundance within size class 88.9 mm since 1984 may be attributed to the increase in the Icgal-size limit implemented by the State of New llampshire. Lobsters in this size class, measuring 3-1/8" to 3-3/16" which had been available for harvest through 1983 were now protected until their next molt. New llampshire inshore lobster landings reported for 1984, the first year the change was enacted, had decreased by nearly twenty-four percent based on information obtained from state-required annual reports. Ilowever, adjusting catch for a generally poor catch in the southern Gulf of Maine in 1984, the actual reduction that was due to the change in 283
11 l iIIllllllllll
+ 7 e c 8 h t
t a 6 8 s u n a c 5 i r 8 e m a . 7 s8
" 4 u9 8 r1 a
m , ot Kr 3 o f p 8 oe R h ce 2 t n ai 8 cl e d s ea zB 1 R i 8 A sk E o Y l o ar gb 0 ea l e 8 S b u s . 7 9 d8 7 n9 a1 l 5 a7 8 g9
\ 7 l
e1 L f e A - ot i G 7 sS E L 7 n L oe A B G s g U E ___ i r S L ra 6 a a. 7 pc E E ms oi CD
- 5 .
7 2 6 0 0 0 0 0 3 0 1 8 M 4 2 . 3 e r u g _ i n mV
% mmA oEo r F wE l
i n.
~ &
8 i
. .c:
N 8
- G
} 3 il{WT. .
l.' 1 - E
.l. ,
6-8 i fM- ~
! O a E-E ~
$._I
! M -i is jj Il,!!,I
[ M -s i i i i 8 8 8 ? 8 " g n dlH1 dVH1 SL H3d Ho1VD $ C 285 ~. - _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ .
l size limit was approximately 13% (Edward Spurr, NHFG, pers. comm.). This
~
resulted in an estimated 28%. loss in total. catch weight in.1984 (Perry 1985). Preliminary data reported to the. state in 1986 indicated that the catch-weight had recovered (Edward Spurr, NHFG, pers. comm.). Data for 1987 were- L not available in time to be considered-in this report. This agreed with l results from this study,.which showed'an! increase in legal-sized lobster catches in 1986 to 1983 levels (Appendix Table 3.3.6-1). Female' lobsters have represented nearly 60% of'the total catch for I all years at the discharge (NAI 1984b)Laithough percentages have bean lower j (54-56%) in recent years. Egg-bearing female lobsters comprised 1.'1%~of the. catch in 1987 slightly greater than in 1985 and 1986 but still consistent with previous years' data (Figure 3.3.6-4). i 3.3.6.2 Rock Crab (Cancer >1rroratus) and Jonah Crab (Concer borealis) Larvao Cancer spp. (Cancer borealis and Cancer Arroratus) larvao generally exhibited a pattern for all sampling years of very low or near-zero density from January through April with rapidly increasing numbers in May, reaching peak abundance in August and declining density from October through ! December. At plankton Station P2, Cancer spp. larvae were usually most abundant during August, except in 1981, 1983, and 1987 when density was greatest in July (Figure 3.3.6-5). In 1987, from July through. December, the
-l observed pattern was very similar to previous years.
Adults Adult' rock crab (C. Irroratus) and Jonah crab (C. borealls) catches have been monitored since 1975 at the discharge site (NAI 1985b). Since 1982, these populations have been monitored at two stations, the discharge site (L1) and at Rye I. edge (L7). Historically, catches of Jonah crabs have 286
;! ill)1l1ll1!,
I 11j
~
- c mwJ<EmE 0z E<ma hM $ 7 8 9 6 4 2 0 8 6 4 1 1 1 1 1 0 0- 0 - _ - - - - - . - 4 7 _ 9 7 8 1
.:.:: / 6 t e
.a .
8 i S e 5 g r
- 8 a
. h c
,4 s 8 i s
D
~.
S ' 3 e E , h L % 8 t H A ' C M ' t T A E 2 a F . C G N N I I
."'j 8 t
a a S E RA . 1 8 d _ L E 5 .* h . _ A B .' R c7 MG .i.i.: A t8 0 E a9 _ E G F E e;:l: . 8 Y c1
%% .;.:.:: r ,
et f:'. ' 9 7 t r so
- \.,'.. b p oe
- 8 lR
- ?.~.. i 7
- :"f;. ee l n
.;.:/ : 7 ai ml
; . : . : .1 :1, 7 ee f s
.:.:.::i a
.I I
- 1 ;;: .
- 6 fB o
7 k
'....' yo ro
'.. 5 ar
- 7 mb n a we SS
- i 4 _
7 .
- - - - - - 4 4 2 0 8 6 4 2 6 6 6 6 5 5 5 5 3
3 Ion <o z mm:<1E g e r u g i F __ o oc~ lll! ll ll .Iil,
E
-,'- .E D
~
f
.AC N
~. .
'.,~. T
.C
.'.'.*.I.,." O
.,i i'.*.'. P
.E S
- N
. _ A E .G U M A y S*
R A E Y_ 7 L u 8 9
.U A J 1
H
._ T N
. N O
. .U M
.:: : . J
*.:e ** Y
/ .A
.!::: E M
- . l f;:: R P
A R
.A M
' B N
A J 6 5 4 3 p 1 0 Woz4azD$ O+5 cOs. . w** i !
I s been significantly greatest in August, although catches were occasionally higher in September at both stations (Table 3.3.6-5). Average monthly catches per fifteen-trap trip have ranged from 0.6 to 26.7 at the discharge I station and from 3.0 to 31.5 at Rye Ledge from 1982 through 1987-(Table 3.3.6-5). The total annual catch of Jonah crabs increased from 1982 through h 1985, when catches were significantly higher than other years, and declined ] in 1986 at both stations (Tabic 3.3.6-5). In 1987, the decline continued at ) the discharge station but catch increased at Rye Ledge.
. Catches of Jonah crab at the discharge site from 1982 through 1987 were not significantly different from year to year. However, monthly catch l data during August and September was significantly different than other
} months (Table 3.3.6-3). A paired t-test comparison of the discharge site and the farfield station, Rye Ledge, did not indicate a significant difference between the two sites (Table 3.3.6-4) for Jonah crab, however. Catch of rock crabs has ranged from 0.0 to 6.7 per fifteen-trap trip at the discharge station and from 0.0 to 2.9 at Rye ledge from 1982 l through 1987. The catch of rock crabs has also been generally increasing from 1982 through 1985, when catches were higher than all other years; catches then decreased in 1986 at both stations (Table 3.3.6-3). Rock crab l catches have generally been greatest in July or August, and since 1984 have been greatest at the discharge station, l i Rock crab catches at the discharge site from 1982 through 1987 were d significantly different from year to year (Table 3.3.6-3). Monthly catch l data, however, was not significantly different. Comparin.on of station f t differences between the discharge site and the farfield station, Rye Ledge, indicated that the discharge site had significantly greater catch than at Rye j Ledge (Table 3.3.6-4). j Total catch of rock crabs has been low at both stations relative to t.he catch of Jonah crabs; this may be due to intra-specific competition between the two species of crabs (Richards et al. 1983). Also, rock crabs
)
i 4 289 1
.- _ _ _ _ _ _ _ _ _____o
l 7 0059001 0000000 7 8 8 0072006 0000000 9 1 0540003 0000000 9 0231002 0000000 1 6 2800006 0000000 6 1100006 0000000. 8 - 8 9 1 1200000 0000000 9 3100000 0000000 1 E S H E T GL 5 0000002 0000000 5 2902002 0000000 GA 8 8 T EI 9 2000000 0000000 9 t t 511001 0000000 A D 1 1 TF
)
S N U IG CN 8 4 3190004 0000000 4 9064003 0000000 RI 9 8 T A ER 1 6412002 0000000 9 1012201 0000000 1 R PA O E R B 3 0340006 0000000 3 1320008 R 8 0000000 I 9 8 1 0210000 0000000 9 2110000 0000000 1 R E C 2 N 8040009 0000000 2 4600000 0000000 8 8 A 9 3010000 0000000 9 7400002 C 1 1 0000000 ( B A R 7 6303045 0843005 7 3030393 C 8 8 0431003 9 838741 8 0897005 9 49371 12 K 1 2678897 132 2 0639003 C ~ 1 1 677867 34 3 O R . 7 6 976671 8 0047828 O89 8 6 83781 59 0030308 9 319581 5 8 D A1 0027649 9 0638598 0030305 1 6789888 34 1 5688977 3 8 1
) ,
S Srf I L O f E 5 7667665 0600664 5 5049428 1 090593 A 8 8 A P t 9 4917525 0100757 9 6042401 E E D 1 6588877 541 4060771 R R F 1 3589877 9090358 O 1 1 BE T N N 4 1103675 0935003 4 RI E 8 8 5094005 0507007 E L C 9 3723199 0682001 9 C E R 1 5578866 1026806 0056C03 N S E 1552 1 4568786 1 1 51 A A P C B ( 3 3859232 0100005 3 K 8 0797506 0030001 BO 9 1042818 8 AO 0900001 9 0672600 0060001 RR 1 6779887 1 5578877 CB A HE 2 1970003 0700006 2 AS 8 4238911 0900007 N 9 7164042 8 O 01 00003 9 7091 059 0900001 J . 1 5588877 2 1 3589776 20 2 7 1 F8 O9 1 . S- 7 6252543 2252106 7 3741 633 C2 8 18341 08 a8 9 0956211 8 t 9 1 22 1 0421001 9 1770110 0021000 s1 1 22 1 p a. l AE 6 i r TG 8 5665623 3722724 6 9654431 5022506 t SD 9 7968563 8 r I 1 21 1 2331122 9 5871778 0200000 e HL 1 1 p C TE m s AY T 5 3274770 7376371 5 p CR RR 8 8 7058715 5298697 a EO 9 9461 914 2560354 9 r Be PF 1 1 21 11 1 7619734 1 3 1120111 t Al F 11 RA HE 5 C C 1 E TT 4 6553295 7045223 4 FT AI 8 8 9434350 2756620 m OI CN 9 3419787 0231 001 9 5691880 o ( S U 1 1 1 11 1 0111001 r N f ( E SG h IR RA 3 891 4381 290201 4 3 4668600 c 8 8 4932025 t AH 9 2628416 0010000 9 a PC T 1 1 1 4239438 0010000 c S 11 GI CD l a 2 7994703 0700122 2 t 8 8 6206459 2511011 o 9 2348234 0000000 9 t 5 1 1 3345333 O100000
- =
6 N t 3 O r I NLGPTYE NLGPTVE NLGPTVE o 3 T A UUUECDG JJASONA UUUECOG JJASONA UUUECOG B UUECOG E t LGPTVE f f E T R R JJASONA R JJASONA e S E E R B V V E E t - A E A V V i T G A E A A n R G u A Y Y D Y Y B L L E B L H A R B R L A R L r C R A A A B R e S I D C H A E Y C R E Y E Y R R C H A E Y C A R A E Y h c p K A K N O C O N C t a _ A J R
. O O C B J R w
@o llll
l prefer sandy habitat which is available near the_ discharge site compared to rocky habitat preferred by Jonah crabs (Jefferies 1966; Bigford 1979). The percent of female crabs in the catch has been monitored since j 1982 (Table 3.3.6-5). The highest proportion of females at the discharge station occurred during September in most years, ranging from 83.3% to 95.6%. In 1987 the highest percentage of females was in November (91.4%). At Rye Ledge, they reached their greatest proportion in September or October (81.3 I to 95.1%). Female catch of Jonah crabs generally increased from 1982 through 1987, particularly at the discharge, due to larger catches and higher pro-portions of females. Trends of female rock crab occurrence were less defined than Jonah crabs due to the. low overall catch of rock crabs. In 1984-1986, catches of female rock crabs were generally greatest in the fall, but some earlier months had greater percentages in some years due to a low catch comprised of only female crabs (Table 3.3.6-5). Percentages of females in 1987 were higher than most of the previous years' catch figures. Egg-bearing 1 Jonah crabs were most abundant in 1987 at both stations (about 3% of the i total catch), occurring mainly in June or July, compared to generally less I than 1% of the total catch at both stations from 1982.to 1986. No ovigorous rock crabs were collected in 1987 at either site, similar to findings from 1982 to 1986 (Tabic 3.3.6-5). This is as expected, considering the low catches of rock crabs and the low proportion of the population that would be ovigorous females. Width frequency distributions taken in 1985 and 1986 Indicated that male Jonah crabs were slightly larger than females, although ovigerous females were slightly larger than males in 1986 (NAI 1986, 1987a). This trend generally continued in 1987; however, both females and ovigorous females were slightly larger than males at the discharge site but at Rye Ledge, males were slightly larger than females (NAI 1988). Due to low overall catch, trends in the size class distribution of rock crabs were less apparent. Male rock crabs were generally larger than females (NAI 1988). Gear selectivity had an influence on size distributions reported, since catches from lobster traps do not include the smaller size classes in the crab populations. 291
( 3.3.7 #va arenarla (Soft-shell Clam) 3.3.7.1 Larvae Nya arenaria larvae occurred in plankton samples May through October from 1978 to 1987 (Figure 3.3.7-1). Each year, maximum abundances were recorded in late summer or early fall, while in many years a secondary 3 peak also occurred in early sutuer. Peak densities observed in 1985 (63/m ) were the lowest encountered from 1978-1987. The late-summer peak (99/m ) in 1987 was higher than 1985, but much lower than the remaining years, 1978-1986. A late-summer peak in 1987 occurred from mid to late August, similar to 1981-1983. Factors influencing the timing and magnitude of the observed pattern of larval abundance are not fully understood. N. arenaria is known to spawn in the spring at temperatures greater than 4-6*C with summer spawning at 15-18'C (brosseau 1978). Maximum larval abundances in August and September coincided with water temperatures in llampton liarbor that regularly exceeded 15-18'C. Ilowever, these temperatures also occurred frequently in June and July, which were characterized by much lower larval abundances, suggesting that temperature is a minimum requirement for spawning. In addition, recruitment of larvae of non-local origin is likely due to currents in the Gulf of Maine, which may move water masses and their entrained larvae significant distances before larval settlement. The late-summer peaks have been observed to be coincident with northward-flowing currents. This implies that these offshore larval peaks may in part have a more southern estuarine component. Overall, factors controlling the occur-rence of N. arenarla larvae off flampton Harbor Beach are complex, the result of environmental and biological factors including: adult condition at the time of spawning, temperature at spawning sites, location of spawning sites relative to prevailing coastal currents, water column stratification and larval behavior. 292
7 8 9 1 - 8 7 9 1 5 4 2
' P -
. :' t
..' n
~. . * .
5 3 L o
- 5 2
U J i t a c
. t 5 1 s
.' t7 a8 5
4 9
'.'.'. e1
**I E;..;*
5 3 N U J a vr ro af 5 2 l
. n 5 1 aa 1...;; i e
, : .1;
.t1 rm a
5 4 ny el
- . .:: .:.:t o t 5
3 Y rk ae J A e
- ,':.*x.t ...* 5 2 M aw y
- - Nd
- I n 1 \
1 5 1 f a o 1:\ l
$::;. .
- 5 4 ra
- :.:l:::t: - .*-
5 3 R P ev t r ee mt
- A n 5
2 ci
- i
- b e 1 t.' 5 1 uc ;
%...;.t;;:1 cn -
> ' 5 e'. _
~ 4 rd7 _
/
~ -
' ei8 pf9 N ::* ::.
5 3 R n1 A A eo E .:.:::::: M cc , M. *
- 5 2 n t t
L .\' a%r A .' d5 o - R ' 5 1 n9 p E 7 8 u e V O 9 .l:, bdR 1 5 4 an
.' ae
.. 5 3
)
1 ni n - B + al E xee 5 2 F ( msa g B 5 1 o 's l rk yeo ao 5 4 N l yr A k b 5
'3 J el a el e
- - - - - - - WaS 0 5 0 5* o- 5 0 3 2 2 1 t 0 0 .
1 7 3 _ 3 EmVW;E o m3U mmG - e r moz<ozpm< ne+x~ UO'- . u g i F wmu
, llll , L
'A comparison of larva 1' densities at nearfield (P2) and farfield (P7) stations-Indicated similar patterns at the two stations,. 1982-1984 and l 1986-1987 (Figure 3.3.7-2). Only St'ation P2 was examined in 1985. In~1986 and 1987, llampton liarbor Station P1 added in July 1986, was also similar to patterns at P2 and P7 (Figure 3.3.7-2).
3.3.7.2 Reproductive Patterns Developing stages in the Nya reproductive cycle in the llampton-estuary appeared in March or early April during most years. Alpo individuals were observed between the second week in April and the third week in June'. In most years, ripe individuals occurred at'similar times at both flampton liarbor and Plum Island Sound, with the exception being 1984 (NAI 1985b). The onset of spawning in Hampton !! arbor and Plum Island Sound, as indicated by the reproductive studies, usually occurred following the appear-ance of larvae in offshore tows. Only in 1980 and 1981 was spawning detected before larval occurrence. The peak larval abundance always occurred well
~
after spawning had commenced, indicating both Hampton liarbor and Plum Island Sound clams may contribute to the large nearshore larval densities of late ' summer (NAI 1985b). 3.3.7.3 Hampton liarbor and Regional Population Studies llampton liarbor Spatf all i The soft-shell clam population has been studied through intensive surveys of spat and adults in Hampton Harbor (Appendix Table 3.3.7-1). These surveys have been supplemented by quantitative studies of regional spat' fall in nearby estuaries, where settlement is known to occur. Over a 14-year j period, the llampton Harbor population has gone through substantial changes in abundance. The Nya population structure during the 1984-1987 period j 294
m 4.0 - 1982 g 3.5 * { ," i $g 3.0 - zw 2.5 - / 3g STATION P2 y2 2.0 - ~~.. STATION P7 ,/ O 1.5 -
+ o- 10 uo *
~U g.$ , ***..,... ,..**.. . . . , , . .
~..
gg o.o
.a n.
APR4 W WAV 1 MAV 8 MAY4 MAf 4 AMI JA68 A364 A364 4 t M4 M4 M4 ALS t ut AL44 AUG4 MP1 MP4 W4 8874 M f OCT4 CCT4 MONTH w 3.0 - 1983 o i 2.s - om ,'. zW 2.0 - l. pg m ~~.. STATION P2 STATION P7 l '
<a l
1.5 . , ...,.
,o 1o. . . - - ., ... -* iii *'
x8 o.5 - *~'*..,..** ., ,,, , ' Om o.o - OW
.a n.
AM4 API 44 MAf-t MAf l 16AY4 AA6) JM8 JA6@ A364 M.t M.8 JA4 M4 Aug.g Augg Agg4 g4 gp.1 MP t 8E74 MP4 OCT1 OCia 0C74 QCf4 MONTH w 3.0 - 1984 0 z 2.5 - g A STATION P2
$w z 2.0 - l.*.....',,...a.. ~ ~ . . . STATION P7 mWa m 1.5 - !
N, ..**** j ., O 1.0 - ! . i- iii l '....* . l u +a 0.s - *
~0 l ./
Om o,o_ ** \' 's ; oW
.J G.
i i i i i i i . i i . . . . . . . , , , , . , , , APR4 API 44 MAV4 M49 8 NAV4 MAV4 AJI66 AA6) AA64 AA64 AR,.1 Mj M4 M4 g.g gg g4 g4 gp4 gp.g gp.g g4ggy,g g g MONTH Figure 3.3.7-2. Log (x+1) abundance per cubic meter of Nya arenarla j veligersatnearfieldstationP2,farfieldsgegion P7 and Hampton Harbor station P1, 1982-1987. ' Seabrook Baseline Report, 1987,
- a. Only station P2 was examined for Nya'veligers in 1985.
295
30 1986 w STAT M P2 u a.-.. STAT M P7 2.5 - l- z ... .- STATM P1 1 < . OE 2.0 - .- zW . i 2b m 1.5 - / o
/ i.
'. s $.
! /.*,.* %. ' .'..g
<3 ,/ '.
i ', o 1.0 - , . i ..
'! s.**.
7E x3 0.5 - .'
/ *
. 's. ./
/
. jl
-u '.
. ' ~ . .~ . . , h. .~.
1 1 0x 0.0 -
. .. - .*..V:! ~
.-.- ~
Ow
.J Q.
m m .v., m
.,.4 .,.. .
. = = u.i ui u4 m ai s4 - w wa w. m a m MONTH 3.0 - 1987
$ 2.5 -
STAT W P2 sTarm P7 z .
< ... .- STATm P1 QE 2.0 - f**.)*
zW ;
.e.,'...=,p.'~.\
.i s.
pD a 1.5 - l
! ;\
- s. A !
s*
+
s.g'. 4E l '. *
\ ' j.'.
. . l '., ,! '
....g.***
.' ., lI
o 1.0 - A j 't
\ ~.',*
s.
, t *~..
"m
+ *'.
/ . / 's a. ! /. *
'.....s.* ,! V, uoO 0.5 -
o .
's l '. '
4.s .
..l*.
. t..:
~
Ox 0.0 - - --*- % OW
.a c. . . . . . . . . . . . . . . . .
- m. m us.. i .
us.s u,. s un . m ma m m u.i ua na n a. as ma a wa w.s wa w. ocu m as a
. i . . i MONTH i
i 1 i i I Figure 3.3.7-2. (Continued)
- b. Station P1 was added in June 1986.
296 ,
1 l l resembled that observed in 1974-1975, suggesting long-term trends based on the interaction of spatfall, and disturbance possibly due to natural and human predation (Figure 3.3.7-3). The continuing decline in juvenile and adult l I (>25 mm) clam densities is partially the result of light spatfalls (1982-1987). The size distribution in 1974-1975 also indicated a decreasing L juvenile and adult (>25 mm) population with an absence of any clams between j 5-25 mm in 1974 and 1975 except for the young-of-the-year settlement (1-5 l } mm). In 1976, a large settlement occurred at all flats (Figure 3.3.7-4) l l 1 which initiated changes in the population during the 1976-1982 period. The current state of low juvenile and adult densities is not likely to be reversed without significant spatfall. j l i The 1976 spat settlement was the largest observed in the study; however, other important settlements occurred in 1977, 1980, 1981 and in 1984 (Figure 3.3.7-4). The 1976 recruitment was successful on all flats, while ) the spatfall in 1980 and 1981 was most successful on Flat 2 and in 1984 on Flat 4. In llampton liarbor, the least-successful recruitment years occurred in 1974, 1982, and 1985-1987. I Regional Spatfall The regional spatfall study verified that the large 1976 recruit-ment occurred throughout the region (Figure 3.3.7-5). Generally, spat recruitment was similar between estuaries, though variation between flats l 1 within estucirles was of ten considerable. Overall, 1987 had the lowest . abundance of spat observed in the regional study. In 1987, Flat 4 and Plum l Island Sound spatfalls were the lowest observed during the 1976-1987 period while Flat 2 spatfall was higher than 1982 but lower than all other years. Yearling and Adult Clams Yearling clams (10-12 mm) became numerous in 1977 following the 1976 spatfall and began showing a decline in 1981 at Flat 1 and 1982 at Flat 297
. - .rr .. ..r.
p.. .. . t
/
l l
..I . IlI
. ..i I. u n.n._n u n. n n,n......1
..I .
II
. li.t. illa. n.i.nu.t : n.u.
. . ......n
- a. ............. .. .._..
/ ..,.
..r.
. 'j
... .. fl.l .l............n.
. . . n. ...... ..,..n.nur..nu.u. s .n. su. n,.,.ni.n. .: n... i.. ._
..I
. . . . . .f.Il}}{lli.n.in.i.n
. . .. i
.n........................ _........ ....
,.r.
. l. 0 s
'f 1
. . .. ,. _ l.in...Illl.l.ini.l.l!!flfl!!.f.!ll!.!!!Il.llllf!.IlWLn 1 : I ll ...n : I n..: . . .. . ..-
.. r i i.re
,,l , , , , , , , II[Illilillfitf n .lf..g...g...g ..;g..;g..
1 4
...i
. . . . . ...ilu.lilll.llll.llllll
.. .l .ff !{lIl l.[.llli.lllll.lllil.nnn,.nu.ni..
i ..:................ .... .......... 1 Figure 3.3.7-3. Abundance (No./ft8) of 1-mm size classes of Nya arenaria in Hampton-Seabrook Harbor during early fall, 1974-1987 (Note differences in abundance scale). - Seabrook Baseline Report, 1987. 298
~ 1
, 1983 e j l
.... 1 l
}- I i .. !!llbL.n... ..iNiillll! O!Ill!!!ilifnrNtratu.t..t........r...... ... .. L.
.I 't llIU llll llt!!!!!)}!!!!(.f..t....!....lft!N!!!!!11t!!ill..,
p , , .
. . . . llfff....l. .. Iflillll!$!!!!n!! ,I e.n n s =.
w 1982 l to85
..........[ ' Irvinummuili~n. iiiiiu ni m iiiiifll}lf t fil$liii m u n iiiiiiiiiiiiiiiiiiiiiiiiiiiiiii.,
*.. !!ll!!I!!! !! !!!(flf!!!!!!!!111.. .!!! .if f. ..l.... ,
. . . . . . . . 1 i
_ a l
.... j i
ll . . . !N.N ! !n! .N.N!IN. !!N..N!.I!IN.!
. hN.k.!!!.!.!!I5.N.N!!! nil!.III! !N.N.Y!! l !!.Il l ........_..,!....
... . . .. .. . .. .. . ,. ..NN.I! $N..!!l...
_ lf _l. . l .! . _: l
,eer l
l l
*l l
l l t
'h f [R IIIII liiiiiiiiiiiniiiiEiiiiiRiifIfi;ililii iis I i
....,..... . . ..... l 3
i Figure 3.3.7-3. (continued) .. -
)i 299 l
)
l i
FLAT 1 3.0-p 2.5 -
+
x
~'
2.0- - 0 . O d 1.5-g o o .. in o
' 1.0 - ' "
z . .. o ..
.w " "
Q 0.5- " " {- { j .. . o .- 0.0 i , , , , , , , , , , , , , . 74 75 76 77 78 79 80 81 82 83 84.85 86 87 YEAR FLAT 2 3.0 - n - 2.5 - 5 . x
- o 2.0 - ..
c . O
.J 1.5 -
o . b e.
$ 1.0 - o g .
u w o o o . c 0.5 - " 0.0 i , , , , , , , , , , , , , 74 75 76 77 78 79 80 81 82 83 84 85 86 87 YEAR FLAT 4 3.0 - 2.5 - " P +
!$. 2.0 -
e *
.. o O 1.5 -
a o ,
> .. o
$ 1.0 - , , ..
w J, O . 0.5 - - lI 0.0 l, , , , , , , , , , , , , , 74 75 76 77 78 79 80 81 82 83 84 85 86 87 YEAR l Figure 3.3.7-4. Annual mean density (number per square foot) and 95% i. confidence limits of young-of-the-year Nya arenaris (1-5 mm)'at Hampton-Seabrook Harbor, 1974-1987. Seabrook Baseline Report, 1987. 300 4
4~ f _
- HAMPTON HARBOR FLAT 4 o 3- .. .
x .. . e n . O " n ,d- 2-p ii ii e .. n n E 1- - m o , o i i , , , , , , , i , 1976 1977 '1978 1979 1980 1981 1982 1983 1984 1985 1986 '1987 YEAR I 4- HAMPTON HARBOR FLAT 2 ) . E "
~
3- I -
.o e ..
O d 2- u o o n C '
! 1- .
w Q 50 mm) were recorded in 1980 and have declined from 1983 through 1987 (Figures 3.3.7-6, 3.3.7-7 and 3.3.7-8). The 1980-1982 adult densities reficcted the success of the 1976 and 1977 year classes; subsequent decline resulted from the harvesting of these clams (see below) and the failure to recruit the spatfalls of 1980, 1981 and 1984 into the juvenile and adult size clams. The New Hampshire Fish and Game Department seeded Flat 5 with 45,000 juvenile clams in late June of 1987, but during a qualitative survey of Flat 5 in October, no clams from the seeding experiment were found. In order to better understand the patterns of population structure, growth and survivorship of the one-year and older clams, the size-class density distributions were separated into year classes utilizing NORMSEP (Hasselblad 1966). This method attempts to fit normal distribution curves to complex frequency distributions so that the mean and standard deviation of each cohort can be estimated. A chi square test was also performed to test the difference between actual and predicted distributions. The resulting mean sizes and density for each year class for each year (1976-1984) were utilized to provide estimates of survivorship (density remaining) and growth. The relative paucity of juvenile and adult clams, 1985 through 1987, did not warrant a NORMSEP analysis for those years. The 1976 year class (Figure 3.3.7-3) was most easily traceable as few juvenile and adult clams existed when it? entered the population. By November 1976, the clams reached a mean size of 2.5 mm. It took four years until these clams began appearing as harvestable adults in 1980, with a mean size of 48 mm. Subsequent year classes experienced similar growth patterns, but older years were more difficult to separate successfully. , l An examination of survivorship from the NORMSEP analysis of size density data, indicated that the 1980 to 1982 year classes experienced far 302
2- 13 25 mm SPAT ss . I E8 ww om
;e< 1-So c.
m .. I f $$ .. T - . r 0 ; i i i . . . . =. . . . i 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 YEAR l 2- 26-50 mm JUVENILE
$s 58 ww om "
p<m 1-on m xo m ee Ow T 1 ~ I I I , , 0 . . T . . . . . . . . i i 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 YEAR 0.75 - > 50 mm ADULT Cs .
!w8 w 0.50 -
ow .
?m oo Xo
-m 0.25 -
a, ". .. o Ow * -
.J o. !
0.00 . i i I i I i T i i i . . . i i I i 1974 1975 1976 1977 1978 1979 1980 1981 1082 1983 1984 1985 1986 1987 YEAR j i i l Figure 3.3.7-6. Means and 95% confidence limits of spat, juvenile and adult log (x+1) densities at Flat 1, Hampton-Seabrook Harbor, 1974 through 1987. Seabrook Baseline Report, 1987. 303
15- 13 - 25 mm SPAT
$s 4 ..
1 i8 W u- 1.0 - aw .. m 74 -
+3 E@ 0.5 -
ga .. at - 0.0 i i i , , i i , , , 1974 1975 1978 1977 1978 1979 1980 1981 1982 1983 1984 1985 1988 1987 YEAR 0.6- 26 - 50 mm JUVENILE , ,, ,, y$ 0.5-z W 0.4-ow OE= 0.3 - - ES 0.2-oe .. .. Og 0.1 - - 0.0
. I .
. . T. . . . . . . . T. . .
1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1988 1987
. YEAR
<0.7- > 50 mm ADULT .
b 0.6-m -
@ u. 0.5-e 0.4 - -
jg 0.3 - , g 0.2- - u 3E 0.1- . . 0.0 , , Y , , , , , , , , f 1974 1975 1978 1977 1978 1979 1980 1981 1982 1983 1984 1985 1988 1987 YEAR 1 Figure 3.3.7-7. Means and 95% confidence limits of spat, juvenile and .j adult log (x+1) densities at Flat 2, Hampton-Seabrook Harbor, 1974 through 1987. Seabrook Baseline Report, 1987. 304
2.0 25 mm SPAT i i Cs ..
.l l8 w u.
1.5 - .. I cm l i ! pE 1.0- ..
.. I on .l M, O, ..
a 1 eg 0.5 -
- 3E ; T T 0.0 , i e i .. i s. i e i i i 1974 1975 1978 1977 1978 1979 1980 1981 1982 1983' 1984 1985 1988 1987 YEAR 2.0- 26-50 mm JUVENILE t: H l E 1.5 - '
w aW - pi 1.0 - "
+3 xg <
cg 0.5 - I SE y I I I r 0.0 i . . . . i i i e i i i i i 1974 1975 1978 1977 1978 1979 1980 1981 1982 1983 1984 1985 1988 1987 YEAR l 1 l 0.6 - > 50 mm ADULT " 58 W' O.4 - o cm oc < o3 - - 210 0.2-eg " se " I I 0.0 i i I I I i i i i i i i i i 1974 1975 1978 1977 1978 1979 1980 1981 1982 1983 1984 1985 1988 1987 YEAR Figure 3.3.7-8. Means and 95% confidence limits of spat, juvenile and adult log (x+1) densities at Flat 4, Hampton-Seabrook Harbor, 1974 through 1987. Seabrook Baseline Report, ' 1987. 305 i j j
s. greater mortality during the first two years than was observed for the 1976-year class. The higher mortality for year classes 1980 through 1986 (Figure 3.3.7-3) corresponded to an increase in density of its main predator, the-green crab, during this period. Each year class during 1982-1986 appears-to have been. virtually eliminated by its second year. L Predation and liarvestable Clam Resources s Clams in llampton liarbor are subject to predation pressure from two l' major sources: green crab consumption of spat (1-25 mm) and juvenile (26-50 mm) Nya, and humans who dig adult Nya (>50 mm) but also cause mortality to smaller clams by disturbing the flat. Sea gulls may also be major predators, as they are commonly observed picking ever clamdigger excavations for edible invertebrates, including spat'and juvenile clams, The green crab (Carcinus maenas) is a major predator of Nya, with clams being a major source .of food particularly in the fall months (Ropes 1969). Green crab catches in llampton liarbor have shown a substantial increase in abundance since 1980 (Table 3.3.7-1). Maximum abundances usually occurred in the fall, with the highest number recorded in 1984. Green crab numbers, from 1983 to 1987 appear'to ; have stabilized somewhat at higher densities, with fall abundances fluctu-ating between 69.3 (1985) and 123.9 (1984) CPUE (catch per unit effort). Green crabs generally feed more actively at temperatures above i 9'C, and females are more active predators on Nya than males (Ropes 1969). ! The presence of more females in the catch in llampton liarbor from July through l September (1981-1987) indicated greater predation pressure for the newly-settled spat in the estuary. Continued high catches of males and females occurred until late November or December when temperatures declined below 7"C l and activity decreased. q
- k Welch (1969) and Dow (1972) have shown that green crab abundances increased markedly when winter temperatures were warmer. Green crab CPUE by d season 1978-1987, showed an increase from fall of 1980 through 1984 and again in 1986. The increase in green crab abundance corresponded to elevated winter minimum temperatures observed from 1981-1984 (Figure 3.3.7-9); a \
306
a TABLE 3.3.7-1. AVERAGE CATCH PER UNIT EFFORT , PERCENT FEMALE, AND PERCENT GRAVID FEMALES FOR CARCINUS #AENAS COLLECTED AT ESTUARINE STATIONS FROM 1977-1987. SEABROOK BASELINE REPORT, 1987. AVERAGE FECUNDITY SAMPLE CATCH PER PERCENT (% GRAVID YEAR PERIOD UNIT EFFORT FEMALE FEMALES) 1977 Oct-Dec 17.5 47.4 0.3 1978 Apr-Jun 7.5 76.7 7.0 Jul-Sep 8.6 56.5 3.2 Oct-Dec 7.2 56.5 0.5 1979 Apr-Jun 6.4 50.0 6.0 Jul-Sep 6.0 60.0 0.6 Oct-Dec 22.1 60.0 0.0 1980 Apr-Jun 6.7 52.4 8.4 Jul-Sep 15.8 50.0 2.3 Oct-Dec 53.1 66.7 0.0 1981 Apr-Jun 39.5 60.0 4.6 Jul-Sep 34.0 67.7 1.6 Oct-Dec 39.4 54.5 0.0 1982 Apr-Jun 37.4 61.5 4.1 Jul-Sep 44.6 80.0 0.8 Oct-Dec 56.1 66.7 0.0 1983 Apr-Jun 47.5 61.5 3.7 Jul-Sep 61.8 66.7 1.0 Oct-Dec 117.4 61.5 <0.1 1984 Apr-Jun 84.7 54.5 2.4 Jul-Sep 80.6 73.0 1.2 Oct-Dec 123.9 58.3 0.0 1985 Apr-Jun 58.3 56.5 3.9 Jul-Sep 54.8 68.8 1.0 Oct-Dec 69.3 58.3 0.0 1986 Apr-Jun 52.6 71.4 6.6 Jul-Sep 53.5 73.7 0.7 Oct-Dec 113.5 56.5 <0.1 1987 Apr-Jun 62.0 68.2 6.5 Jul-Sep 76.0 73.9 1.1 Oct-Dec 70.8 66.4 0.0 8 Number of C. maenas per trap per day, eight " box" traps fishing for 24 hours, twice per month. 307
140 - -2 \ . l\ l l \ l . 120 - f i'.
/
l \ E O l \ l \ B n E w 100 - .! . m l \ z S / i -1 x t
- \ . o H l *,.**.
- g . \.
- C 80 - . ! '*
. E A / *. ! *
. 4 1 / '. !
. z l
l . 't n U l l b z l : -
" 80 -
! w
./ \
a x : . : 3 W 4 l '. l
/ '. ! Q
........ 4 .,
j .O g w U H 40 - . a. 4 0
%.*,.**.**.a 3 w
GREEN CRAB CATCH H
...~.. MINIMUM WINTER TEMP, 20 -
i l t 0 . . , , , r , , , , 1 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 . 1 i YEAR ! i Figure 3.3.7-9. Fall mean catch per unit effort for green crabs j (Carcinus maenas) in Hampton-Seabrook Harbor and its ! relationship to minimum winter temperature, 1978-1987. Seabrook Baseline Report, 1987. I i, 308
I i significant correlation (a = 0.05) was obtained between fall abundances (time J of peak activity), 1980-1987, and the previous winter minimum temperature. Close examination of the yearly data indicated the type of response proposed by Welch (1969). Following the winter of 1979-1980 when the temperature minimum was high, the fall cr6b population showed a marked increase (Figure 3.3.7-9). A much lower minimum temperature in winter 1980-1981, and a somewhat higher one in 1981-1982, resulted in a noticeable decrease in crab [ density in the fall of 1981 followed by a moderate increase in fall 1982, liigher minimum winter temperatures in 1983, 1984 and 1986 were associated with a marked rise in fall green crab catches. In 1987 green crab CPUE decreased following a decrease in minimum winter temperature, the lowest since winter of 1981. The increase la green crab CPUE, and associated predation in the years 1980-1987 can be otserved in examination of the 1981-1987 #ya year classes, as estimated by ~lensities of young-of-the-year clams (Figure 3.3.7-4). The 1981 year : lass, which was relatively large, showed decreased survivorship and substantially-reduced first and second year clams (Figure 3.3.7-3). In 1982, settlement was the poorest since 1974 (Figure 3.3.7-4) and the subsequent mortality, probably,related to green crab predation, has virtually eliminated this year class (Figure 3.3.7-3). Recruitment into llampton liarbor clam populations, 1983-1987, has been very low, corresponding to high green crab abundances and low spat recruitment. Welch and Churchill (1983) reported the increase in near-surface temperature at Boothbay Harbor, Maine, in the early 1970s along with an increase in green crab abundance. Although no green crab or temperature data are available for llampton Harbor for this time period, catches from Kittery, Maine, showed a maximum crab occurrence (1973- 1975) corresponding to the reduction in younger year classes observed in llampton Harbor prior to the 1976 settlement. Subsequent reductions in the reported sea surface tempera-ture and related decreases in green crab abundance and piedation along the southern Maine coast (Welch and Churchill 1983) may have also occurred in )t llampton liarbor, which may have contributed to the survivorship of the strong i 1976 and 1977 year classes. 309 I
E Recreational clam digging on the Hampton Harbor flats'is the most-significant source of mortality for clams of >45 mm, but also is a source of mortality to spat and juvenile' clams due to disturbance. Census figures indicate digging activity tripled from 1980 to 1981 (Table 3.3.7-2). This level of effort was maintained through 1982 before undergoing successive reductions 1983-1985. Digging activity increased slightly in 1986 over 1985-levels, but remained-lower than in previous years, 1982-1984. Digging activity in 1987 was the lowest observed in the study 1980-1987. l The changing pattern of clam abundance on the Hampton Harbor flats is reflected in the number of licenses issued by the-State of New Hampshire (Figure 3.3.7-10). Changes in the number of licenses lag the changes in standing crop one to two years illustrating a typical predator prey cycle. Diggers shifted some of their activity in late 1983 and 1984 from Flat 4 to Flat 2 (Table 3.3.7-2.), probably in response to declining resources overall, and particularly at the most accessible area, Flat 4. As clam densities continued to sharply decline in 1985 and 1986 digger activity again shifted, from Flat 2 and Flat 4 to Flat 1, possibly due to slightly greater densities _ 1 at Flat 1. In 1987, nearly 90% of digging activicy was confined to Flat 1 and Flat 4 which had the highest remaining standing crop. Flat ~2, Flat 3 and Flat 5 accounted for the remaining digging activity. ( Morte.11ty to younger clams (<50 mm) from digging is dependent on the depth of burial, the size of the clams, and the time of the year (Glude I 1954). The highest survival is inversely proportional to the depth of burial; the deepest burial tested (13 cm) resulted in the lowest survival. Clams 9-20 mm suffered the greatest mortality (51%) with 36-50 mm clams i:aving only 31.5% mortality. No data has been collected on the amount of dist.urbance caused by digging on the Hampton Harbor flats; however, Flat'1 I and Flat 4, with the highest usage by clammers, would likely have suffered substantial mortality to young clams due to digging. Sarcomatous neoplasia, a lethal form of cancer in Nya arenar.fa, has l i been observed in Hampton Harbor Nya populations (Hillman 1986, 1987). A 310 ;
L l I TABLE 3.3.7-2. ESTIMATED DISTRIBUTION (PERCENT OF TOTAL) OF CLAM DIGGERS BY FLAT AT HAMPTON HARBOR, SPRING 1980 THROUGH FALL 1987. SEABROOK BASELINE. REPORT, 1987. a ESTIMATED ESTIMATED TOTAL NUMBER OF 1 DIGGER BUSHELS l SEASON FLATS TRIPS HARVESTED 1 2 3 4 5 I J Springc 1980 12.5 17.9 1.7 52.5 15.4 3,860 1,200 Felld 1980 11.3 18.4 3.3 55.1 11.8 2,700* 840 j Spring 1981 9.7 15.6 0.8 65.9 7.9 12,500 3,900 Fall 1981 13.9 12.9 0.2 63.8 9.1 7,060 2,200 Spring 1982 12.6 13.0 0.8 67.1 6.4 10,800 3,400 Fall 1982 26.6 8.5 0.7 60.7 3.5 9,300 .2,900 , l Spring 1983 30.7 7.1 1.3 58.6 2.2 7,700 2,400 ! Fall 1983 29.4 14.7 0.5 54.7 0.7 6,690 2,100 Spring 1984 22.1 26.4 0.6 49.9 1.0 6,200 1,950 I 1 Fall 1984 26.9 28.9 0.3 43.2 0,8 5,850 1,830 j Spring 1985 51.6 11.3 0.4 36.1 0.8 6,940 2,169 Fall 1985 63.1 5.0 0.4 31.5 0.0 2,873 898 Spring 1986 59.3 6.4 0.3 33.4 0.6 6,210 1,941 Fall 1986 58.1 6.4 0.4 34.7 0.4 4,713 J,473 Spring 1987 39.4 8.1 1.5 49.0 2.0 1,763 551 Fall 1907 38.8 6.9 0.8 49.8 3.8 1,541 482
- Based'primacily on Friday head counts at time of low slack water; most Saturday counts are assumed from observed Fri: Sat ratio (n=14 pairs) of b2 .24 i .96; seasonal totals have approximate error of i 18% .
Assumes each clammer takes 10 quarts per trip; 1 bushel = 32 quarts or ! 3.2 clammer trips
' Includes the period 1 January through weekend before Memorial Day Includes the weekend after Labor Day through 31 December
- Based on average Spring: Fall ratio for 1981 and 1982 (0.68 i .02) 311
)
1
7
. 98
'.'.*..'.,'i 1
'., \ . .
6 8 9 S SE j - 1 - ES
/. . t 7 HB S
- 5 8
l 8 U C B U . 9 u 9 1 d 1 ak 4 o ,
~
8 eot
~ . 9 h rr tb o
. 1
. a p 3 d ee
~ nSR
~
.~
. 9 8
1 a - ne d on 2 eti
- 8 u pl 9 sn e i
. 1 sas iHa 8
1 s ,B
/ t
. 9 e)k
/
1 s so nl o j:../ 0 eer
. 8 9
chb i s a e ./ 1 l ue l
- bS
_ . 97 9 m( a
- 1 l p .
. co7 r8 8 t c9
. 97 l 1
_ 1 ug- _ ' d n1 _ ai7 7 7 R d9
\ '.' W 9
1 A E f n1 oat , Y
\ . i *.' .
6 rsr
. 97 e o b mb
,'t'.*.*.\: 1 mar ul a i
* 5 N cl s.. . 9 7
1 0 4 1
~~ , 7 -
9 1 7
. 3
- 3 .
. , 7 3 9
.. 1
- e
- r
. 2 7 u 9
g 1 i F
- 1
. . 97 1
0 0 0 D 0 0 0 0 0 0 5 0 5 1 1 mEzmo~3 6
= ma_WIm3a upta I li I
I I' virus, similar to the B-t'ype retroviruses, is known to initiate the disease in Nya (0prandy at al. 1981). Although the infection has been observed.in regions of relatively-pristine. waters, the rate of infection may also be enhanced by pollution-mediated deterioration of the environment'(Reinisch et al. 1984). The infection rate in some #ya populations may reach 100 percent with 100 percent mortality of infected clams (Farley at al. 1986). The incidence of sarcomatous neoplasms in llampton liarbor Nya populations was J observed in October 1986 and February 1987 (Hillman 1986, 1987). Neoplastic infections were more prevalant in February, reaching 6% at Flat 1 and 27% at Flat 2. Infections were absent from Flat 4. Assuming 100 percent mortality of infected clams (Farley et al. 1986), Flats 1 and 2 may suffer significant disease-related reductions in clam production. Ilowever, since no historical data is available on the incidence of neoplasms in llampton Harbor clam population, it is not known if current infection rates are typical or indictative of an increasing trend. In 1987 clam flat surveys did indicate, however, that juvenile and adult densities fell by over 50% at Flat 1 and Flat 2 while Flat 4 remained unchanged. Ilarvestable Clams I l The patterns discussed above have resulted in substantial chenges l in the number of harvestable clams on the llampton flats (Table 3.3.7-3). The greatest adult standing stock in llampton liarbor was reported by Ayer (1968) for 1967. Subsequent years indicated a gradual decline in available adult clams to a low of six bushels / acre in 1977 and 1978. In 1976, the State of l New llampshire applied more stringent clamming regulations, closing the flats for the summer (Memorial Day to Labor Day) and eliminating digging on Sundays and holidays. Survival of the 1976 year class made a substantial increase in the standing crop in 1980, four years after settlement. The number of harvestable clams continued to increase in 1981 as more of the 1976 and part of the 1977 year class became harvestable. 313
l TABLE 3.3.7-3.
SUMMARY
OF STANDING CROP ESTIMATES OF ADULT" #rA ARENARIA IN ifAMPTON HARBOR,1967 THROUGH 1987. SEABR00X BASELINE REPORT, 1987. ESTIMATED NUMBER TOTAL ESTIMATED OF BUSHELS NUMBER OF DATE PER ACRE OF BUSHELS b b November 1967 152 23,400 July 1969 103 15,840 November 1971 94 13,020 November 1972 58 8,920 November 1973 41 6,310 November 1974 56 8,690 November 1975 29 4,945 November 1976 11 1,350 November 1977 6 1,060 November 1978 6 940 November 1979 9 1,400 October 1980 54 8,890 ! October 1981 75 12,400 I October 1982 55 9,200 i October 1983 78 13,020 October 1984 54 8,821 November 1985 39 4,615 October 1986 23 2,793 October 1987 8 976 Shell length >50 mm [FromAyer(1968) I (
)
314
l Through 1984, the number of harvestable bushels had not decreased substantially. Ilowever, in 1985 through 1987, the harvestable standing crop dropped precipitously (Table 3.3.7-3), reflecting poor recruitment observed I in 1980-1984, increased predation by green crabs, and continued human dis-turbance. Since recruitment has remained low through 1987, the trend of decreasing adult standing crop will likely continue for at least another three to four years, assuming a successful spatfall in 1988. } } The distribution of clams by flat has changed since 1980 when the 1976 year class became harvestable (Tables 3.3.7-2, 3.3.7-4). Flat 1 showed a continuous increase in its percentage of adult clams through 1984, while Flat 4 showed a steady decrease. In 1985 the percentage of harvestable clams decreased on Flat 1 and increased on Flat 4, followed by increases on flats 1 and 2 and a decrease on Flat 4 during 1986 (Table 3.3.7-2). In 1987, the percentage of harvestable clams increased at Flat 4, while decreasing at Flat 1 and Flat 2, reflecting the stabilization of clam populations at Flat 4 at low levels, while populations on Flat 1 and Flat 2 continued to decline. 315
TABLE 3.3.7-4. DISTRIBUTION (PERCENT OF TOTAL STANDING CROP) 0F' HARVESTABLE CLAMS BY FLAT AT HAMPTON HARBOR, 1979 THROUGH 1987. SEABROOK BASELINE REPORT, 1987. YEAR FLATS 1 2 3 4 5 1979 33.3 6.2 2.2 55.7 2.5 1 1 1980 45.1 10.5 1.0 39.5 3.9 1981 53.0 7.3 1.5 34.4 3.7 1982 52.2 7.0 1.0 38.4 1.3 1983 62.9 25.6 0.5 10.5 0.5 1984 72.0 13.6 1.9 11.5 0.9 1985 60.2 14.6 NS 25.1 NS 1986 63.0 21.9 NS 15.1 NS 1987 40.0 15.9 NS 44.2 NS I i 316
)
) I 3.3,8 Benthos Anyendix Tables I l 1 l t I i l l l 317 _ _ _ _ _ _ _ - - - _ _ _ _ _ _ _ . _ _ U
I APPENDIX TABLE 3.3.1-1. HEAN HONTHLY SEAWATER SURFACE TEMPERATURE ('C) AND l SALINITY (ppt) TAKEN IN BROWN'S RIVER AND HAMPTON HARBOR, MAY 1979 - DECEMBER 1987. SEABROOK BASELINE REPORT, 1987. t i I BROWN'S RIVER I HAFPTON HARBOR I l l l.......................... 4........................... 1 I HIGH-TIDE I LOW-TIDE I HIGH-TIDE I LOW-TIDE I l ;.............+............ 4.............+.............l TEMPERATURE I MEAN ! CI I MEAN I CI I MEAN 1 CI ! MEAN I Cl ! j
!............... ............................._.............. .............! j IJAN I 1.01 1.261 0.91 0.801 2.51 0.911 1.01 0.691 IFEB I 1.21 0.861 1,91 1.161 2.31 0.891 1.7! 0.681
) IMAR I 3.71 0.881 4.71 0.52 3.71 0.61l 4.l! 0.771 1 IAPR I 7.11 0.771 9.81 0.77l 6.31 0.871 8.11 0.681 IMAY I 13.21 1.811 14.71 0.71l 10.11 0.581 12.81 0.61! , !JUN I 15.81 0.971 19.21 1.14l 13.41 0.741 16.41 0.821 l IJUL I 18.0! 0.991 21.41 0.93l 15.8 0.841 18.41 0.84! IAUG I 18.81 1.05i 20.8! 1.421 16,81 0.851 18.61 0.971 l ISEP I 16.01 0.891 18.01 1.111 14.6l 0.971 16.2! 0.911 10CT I 12.21 1.011 12.3! 1.171 12.31 0.71! 12.21 0.80l lNOV ! 8.21 0.871 7.31 1.581 9.1l 0.761 8.31 1.11! IDEC I 4.81 1.231 2.91 0.611 5.51 0.781 3.81 0.82!
............................................................................ l J
l 1 BROWN'S RIVER I HAMPTON HARBOR I l g...........................+...........................l I I HICH-TIDE i LOW-TIDE I B10H-TIDE I LOW-TIDE I - l 1.............+.............+.............+.............l l SALINITY I MEAN ! CI I MEAN I CI I MEAN I Cl l MEAN I Cl ! l..................+..... 4..... 4......+......+......+...... ..... 4......l lJAN I 31.5! 1.09! 24.01 2.761 32.11 0.671 28.41 2.021 , IEEB I 29.41 2.701 19.51 4.111 31.61 0.761 27.51 2.931 IMAR I 28.71 2.021 17.5! 3.861 31.11 0.981 24.91 2.411 IAPR I 26.41 3.241 17.51 4.56l 30.01 1.84! 24.11 3.821 IMAY l 29.01 1.68! 20.61 3.051 30.01 1.071 26.81 1.891 IJUN I 28.81 1.861 21.21 3.361 30.31 1.061 27.41 2.391 IJUL l 30.31 1.03i 24.11 1.911 31.01 0.561 28.9! 0.811 l lAUG I 30.51 0.431 25.31 1.58! 31.3! 0.43! 29.81 0.621 1 ISEP ! 30.71 1.02l 24.81 2.561 31.51 0.311 29.91 0.721 10CT I 30.41 0.871 23.61 1.48! 31.61 0.311 29.31 0.751 { INOV l 30.11 1.611 21.11 3.291 31.91 0.401 28.31 1.511 l
!DEC I 30.3! 2.061 20.11 3.961 31.71 0.711 27.51 2.441 I
{ 318
u l f APPENDIX TABLE 3.3.2-1. MACROALGAE SPECIES RECORDED IN GENERAL COLLECTIONS , FROM BENTHIC STATIONS SAMPLED FROM 1978 TO 1987 i (a,b,e). SEABROOK BASELINE REPORT, 1987. . { ) SPECIES INTERTIDAL SUBTIDAL 1 5 MSL MLW MSL MLW 17 35 16 19 31 13 4 34 Chlorophyta Acrochaete viridis X* B11dingla minima Xg X X X Bryopsis plumosa X Chaetomorpha sp. X X X X X X Chaetomorpha aerea X l g l Chaetomorpha brachygons X X X X X X X X X jl Chaetomorpha linum X X Xg X X X X X X X X Chaetomorpha melagonium X X X X X X X X X X ] Chaetomorpha picquotlana X X X X X X X X X X Cladophora sericea X X X X X Codlolum petrocelldis Xg Enteromorpha sp. X X X X Enteromorpha intestinalis X X X Enteromorpha linza X X X Enteromorpha prolliere X X X X X Honostroma grevillel X X X X X X Honostroma pulchrum X X X X l Pseudendoclonium submarinum X Rhizoclonium tortuosum X X X X X X X X X X j Spongomorpha sp. X Spongamorpha arcta X X X , Spongamorpha spinescens X X X X X Ulothrix flacca X Ulva lactuca X X X X X X X X X 0 X X X X X X Ulvarla obscura' f Ulvarla oxysperma X X X Urospora penicilliformis X X* X X Urospora wormskjoldll X* Phaeophyta Agarum cribrosum X X X X X X X X X Alarla esculenta X X X X X Ascophyllum nodosum X X Xg X Chordarin flagelliformis X X X Desmarestia aculeata X g X X X X X X Desmarestia viridis X X X X X X X (continued) 319
APPENDIX TABLE 3.3.2-1. (Continued) SPECIES INTERTIDAL SUBTIDAL 1 5 MSL MLW MSL MLW 17 35 16 19 31 13 4 34 Phaeophyta (cont) Ectocarpus fasciculatus X X X X X X Ectocarpus sillculosus X X X X X X X Elachista fucicola X X X g Xg X , Tucus sp. X X X X l Fucus distichus X 1 Fucus distichus esp. l distichus X 1 Fucus distichus ssp. l edentatus X X X X Fucus distichus ssp. evanescens X X X Fucus resiculosus X X X X Fucus vesiculosus v. spiralis X Giffordia granulosa X Laminaria sp. X g X X X Laminaria digitata X X Xg X X X X X X X Laminarla saccharina X X X X X X X X X X X X Leathesla difformis X X X Petalonia fascia X X X X X X Petalonia zosterifalla g g X Petroderma macullforme X X P11ayella littoralis X X X X Ralfsla verrucosa X X Saccorhiza dermatodea X X Scytosiphon lamentaria X X X X Sorapion kjellmanil X Sphacelaria cirrosa X X X X X Sphacelarla plumosa X X X X Sphacelaria radicans X X X X Spongonema tomentosum X X X X Rhodophyta Ahnteltia plicata X X X X X X X X Antithamnionella floccosa X X X X X X X X X X Audoulnclla sp. X X X Audoulnella purpurea X X Bangla atropurpurea X X* X Bonnomaisonia hamifera X X X X X (continued) 320
APPENDIX TABLE 3.3.2-1. (Continued)' SPECIES INTERTIDAL SUBTIDAL f 1 5 1 MSL MLW MSL MLW 17'35 '16 19 31 13 4 34 Rhodophyta (cont) Callithamnion tetragonum -X0^X g X X X X X Ca11ophy111s cristata X X X' .X X X X 1( X. X X Ceramlum deslongchampil
- v. hooperl X X Ceramium rubrum X X X X X X X X 'X X X X Ceratocolar hartzfl X X X X X X X X X Chondrus crispus X X X X X X X X X X X X Choreocolax polysiphonlae X X X X Clathromorphum g circumscriptum X X X X X X X X X X Clathromorphum compactum X Colacanema secundata X X Corallina officinalis X X X X X X X X X X X X Cystccionium purpureum
- v. cirrhosum X X- X X X X X X X X X. X Dermato 11than pustulatum X X X X X X X X X X:
Devalersea ramentacea X Dumontla contorta X X X X X X Erythrotrichia carnea Xg Xg
' g G1olosphoniacapillarfs X X X Hastocarpus stellatus X X Xg X X Gymnogongrus cienulatus Xg Xg X X X X X Halosaccion ramentaceum X 3C g
Hildenbrandla rubra X X X X Leptophytum foecundum X X X X X X X X Leptophytum laeve X X X X ~X X X X Lithophyllum corallinae X X Lithothamnion glaciale X X X X X X X X' X X Helobesla lejollsli X X X X X X X X Hembranoptera alato X X X X X X X X X X d Palmarla palmata X X X X X X X X-Petrocells cruenta X X X X Petroderms macullforme X Peyssonnella rosenvingil g X X X X .X X Phycodrys rubens X X X X X X X X X' X X
'Phy11ophora sp. X X X X X 'X X X X X lhyllophora pseudocera-noldes X X X X X X X X X PhyllopM ra traillil X X Phyllophora truncata X X X X X X X X X Phymatolithon sp. X X X (continued) i 321 i
f APPENDIX TABLE 3.3. 2-1. (Continued) SPECIES INTERTIDAL SUBTIDAL 1 5 MSL MLW MSL MLW 17 35 16 19 31 13 4 34 Rhodophyta (cont) Phymato11thon laevegatlur X X X X X X X X Phymatolithon lenormandil X X X X X X X X X Phymato11thon rugulosum X X X X Plumaria elegans X X X X X Polyidos rotundus X X X X X X X Polysiphonia denudata g X Polysiphonia flexicaulis X X X X X X X Polysiphonia harvey1 X* X* X X X X Polysiphonia lanosa X X X X X X X X X Polysiphonia nigra X X X X Polysiphonia nigrescens X g X X X X X X Polysiphonia urceolata X X X X X X X X X X X X Porphyra leucosticta X X X X X X Porphyra miniata X X X X X Porphyra umb111 calls X X X X X X Pseudolithoderma extensum X Ptilota serrata X X X X X X X X X X Rhododermis elegans g X Rhodomela confervoldes X X X X X X X X Rhodophyllis dichotoma X X X X X X X X 4 Rhodophysema elegans X X X X X X Scagella corallina X X X X X X X X X X Turnere11a pennyl X X a Co11ections from May, Aug, Nov except in 1982-84 uhen: l STA 4, 13, 16, 34 collected Aug. only i b STA 1MLW, SMLW, 17, 19, 31, 35 collected all months STA 1, 4, 13, 17, 19, 31 - 1978-1987; STA 4, 13 not sampled in 1985 STA 34 - 1979-1987, except 1985 STA 16 - 1980-1987, except 1985 STA SMLW, 35 - 1982-1987
'Not collected in 1978-82 period, but recorded in earlier co11cetions Collected in tide pools only. *G. Robin South, 1986 and William Randolph Taylor, 1962 were used for taxonomic nomenclature and identification. ' Species name changes: Hastocarpus stellatus was Gigartina stellata Ulvarla obscura was Honostrona fuscum var. blytil Ulvarla oxysperma was Honostroma oxyspermum 322
l ) APPENDIX TABLE 3.3,2-2. SPARSELY OCCURRING (< 5% frequency of occurrence) MACR 0 ALGAE TAXA IN AUGUST BENTHIC DESTRUCTIVE SAMPLES, 1978-1987. SEABROOK BASELINE REPORT, 1987. Honostroma oxyspermum Enteromorpha sp. Enteromorpha intestinalis Enteromorpha linza Enteromorpha prallfera Ectocarpus siliculosus Giffordia granulosa Sphacclarla cirrosa Desmarestia viridis Petalonia fascia Scytosiphon Jamentaria Dumontla contorta Ceramlum deslongchampli Plumarin elegans}}