BECO-89-053, Marine Ecology Studies Re Operation of Pilgrim Station, Semiannual Rept 33,Jan-Dec 1988s
| ML20246J274 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 12/31/1988 |
| From: | Richard Anderson, Wagner E BOSTON EDISON CO. |
| To: | ENVIRONMENTAL PROTECTION AGENCY, MASSACHUSETTS, COMMONWEALTH OF |
| References | |
| BECO-89-053, BECO-89-53, NUDOCS 8905170036 | |
| Download: ML20246J274 (314) | |
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' nxarineecologyftucfw Related toOperatico ofPti yimitation l l,l 1 Ig SEMI ANNUAL REPORT NUMBER 33 8 JANUARY 1988 DECEMBER 1988 ,
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MARINEEC0LOGYSTUDIES RELATEDTOOPERATIONOFPILGRIMSTATION SEMI-ANNUALREPORTN0.33 REPORTPERIOD:JANUARY 1988THROUGHDECEMBER1988 DATEOfISSUE: APRIL 30,1989 I Compiled and Reviewed by; if42 M M /A h __
Sn M$rn fheriesBiologist l
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25 B n ee il 0 ce Park Braintree, Massachusetts o2184
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TABLE OF CONTENTS -
SECTION l 1
I
SUMMARY
II INTRODUCTION ZII MARINE BIOTA STUDIES IIIA Marine Fisheries Monitoring and Impact IIIA.1 Annual Report on Monitoring to Assess Impact of the Pilgrim i Nuclear Power Station on the Marine Fisheries Resources of Western Cape Cod Bay, January - December 1988 (Char.pcteriza-tion of Fisheries Resources) - (Mass. Dept. of Fisheries, Hildlife and Environmental Law Enforcement; Division of Marine Fisheries)
IIIA.2 Annual Report on Monitoring to Assess Impact of the Pilgrim Nuclear Power Station on the Marine Fisherie3 Resources of Western Cape Cod Bay, January - December 1988 (Impact on Fisheries Resources) - (Mass. Dept. of Fisheries, Hildlife and Environmental Law Enforcement; Division of Marine Fisheries)
IIIB Benthic Monitoring and Impact IIIB.1 Benthic Algal and Faunal Monitoring at the Pilgrim Nuclear Power Station, January - December 1988 (Characterization of Benthic Communities) - (Battelle New England Research Lab)
IIIB.2 Benthic Algal and Faunal Monitoring at the Pilgrim Nuclear Power Station, January - December 1988 (Impact on Benthic Communities) - (Battelle New England Research Lab)
IIIC Plankton Monitoring and Impact IIIC.1 Ichthyoplankton Entrainment Monitoring at Pilgrim Nuclear Power Station, January - December 1988 (Results) - (Marine Research, Inc.,
IIIC.2 Ichthyoplankton Entrainment Monitoring at Pilgrim Nuclear Power Station, January - December 1988 (Impact Perspective)
- (Marine Research, Inc.)
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{ IIID Impingement Monitoring and Impact
)' Impingement of Organisms at Pilgrim Nuclear Power Station: January -
) December 1988. (Boston Edison Company)
IV FISH SURVEILLANCE IVA Overflights j Summary Report: Fish Spotting Overflights in Western Cape Cod Bay in J 1988. (Boston Edison Company)
V Minutes of Meeting 70 of the Administrative-Technical Committee, Pilgrim Nuclear Power Station 11
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SUMMARY
Highlights of the Environmental Surveillance and Monitoring Program re- !
sults obtained over this reporting period (January - December 1988) are presented below. (Note: Pilgrim Station was in an outage from early April 1986 through December 1988, so data reflects a control situation for 1988, with no thermal influence on aquatic resources. For portions of 1988, particularly in April and .May, no circulating seawater pumps were operating).
Marine Fisheries Monitoring:
- 1. In the June-August 1988 shorefront sportfish survey at Pil-grim Station, less than 600 angler visits accounted for under 100 fishes caught. Cunner (40%) and winter flounder (39%)
dominated the sportfish catch. The lack of a thermal component during the 1988 Pilgrim outage resulted in a much reduced sport-fishery success rate, as occurred in 1987 and other outage years covering the shorefront angling season.
! 2. Pelagic fish mean CPUE (Catch Per Unit Effort) for 1988 at the gill net station (241.9 fishes / set) increased 28% from 1987 when 189.6 fishes / set were taken. Atlantic herring (48%) and pollock (33%) were 81% of the total catch. Both Atlantic herring and pollock increased substantially from 1987 and earlier years going back to 1982. A highly significant positive correlation was found for cunner catch (third in 1988) and seasonal, Pilgrim Station opere.tional output (thermal loading to the environment) for 1973-1983, 1985 L 1
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- 3. Shrimp trawl catch for 1988 recorded 31 benthic fish species with winter flounder (51%), little skate (18%) and windowpane (10%) composing 79% of the total. Mean CPUE for all species was 8.3 '(lowest) at the discharge surveillance station, 13.8 (highest) at the intake surveillance station and 10.0 (23 less than in 1987) for all stations pooled in 1988. The presence of substantially larger numbers of small winter flounder caught in the intake embayment, compared to the other stations each year, suggests its attraction as a possible nursery area. Hinter flounder abundance in summer at the intake surveillance station, was significantly greater than at the discharge and reference stations.
- 4. Adult lobster mean monthly catch rate per pot haul, in May -
October 1988, was 0.38 lobsters which is 15% greater than the 1987 rate (0.33). The surveillance area (thermal plume) catch rate was 0.34 while the reference area (control) was 0.25. The seasonal, legal lobster catch rate since 1970 has not been significantly lower in the thermal plume area than in control areas. Signif'. cant negative correlations were noted between legal lobster catch for thermal plume areas, and mean annual and seasonal (May - December) Pilgrim Station output for the !
l period from 1973 - 1983, 1985. The lobster research study, which commenced in 1986, continued to assess two parameters for identifying PNPS impact when the Station resumes operation -
legal catch rate and size frequency comparisons.
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5, In May - October 1988 fish observational dive surveys, 7 species were observed in the thermal plume area. Cunner (77%), pollock (15%) - and tautog (7%) were the most numerous species seen, cunner being most abundant in the direct path of the Pilgrim discharge current. Total number of fishes observed increased 65% from 1987, although still relatively low compared to the early 1980's. Most fishes were in greatest concentra-tions at stations in the discharge zone (50%), followed by the control zone (45%) and the stunted zone (5%). These results are similar to 1984 and 1987 (also outage years with reduced -
discharge current) when most fish were observed relatively evenly divided between discharge and control zones, but unlike 1985 ano 1986 (higher discharge current years) when fish seemed to greatly favor being in the path of the effluent.
- 6. Atlantic silverside accounted for 72% of the 1988 large haul seine (shore zone) fish catch with a total of 21 species collected. The PNPS intake showed relatively higher species
! diversity and seine catches compared to exposed coastal sta-tions. Fish captured in the PNPS intake embayment (second in l CPUE to Long Point) were dominated by Atlantic silverside and sand lance spp., and included blueback herring and winter flounder among the more numerous species. A deeper seine net l
I (10' compared to 6'), to more effectively sample the intake, was utilized beginning in 1984 and results have indicated this area is more similar in fish fauna attraction to an estuary than exposed coastal areas. Results of additional sampling with a smaller foot-seine confirmed the findings from the I-3
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I itrger seines with Atlantic silverside and winter flounder f
l dominating its catch.
Impingement Monitoring:
- 1. The mean January - Decamber 1988 i:npi ngement collection rate was 0.27 fish /hr. The rate ranged from 0.04 fish /hr (June) to 1.13 fish /hr (March) with Atlantic silverside comprising 24.8%
of the catch, followed by Atlantic tomcod 22.0%, rainbow smelt 7.8% and winter flounder 7.8%. Fish impingement rates in 1985 1
and 1986 were several times higher than in 1984, 1987 and 1988 when Pilgrim Station outages had both circulating water pumps off for various periods of time.
- 2. In March 1988, Atlantic silverside impingement accounted for 80.0% of this species collected. They have been one of the most abundant species impinged on an annual basis at Pilgrim Station, predominating in 6 of the last 8 years.
- 3. The mean January - December 1988 invertebrate collection rate j was 2.37+/hr with ctenophores dominating and blue mussel, common starfish and polychaete worms accounting for 26.4%,
19.4% and 13.0% of the enumerated catch, respectively. Four American lobsters were sampled, and the invertebrate impingement rates in 1985 and 1986 were similar to that recorded at Pilgrim Station during the 1987 and 1988 outage years, despite lower circulating water pump availability in the later years.
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- 4. Impinged fish, initial survival at the end of the Pilgrim Sta-tion intake sluiceway was approximately 35% during static screen Washes arid 58% during continuous washes. Only three of the dominant species showed greater than 50% survival, overall.
Fish Surveillance:
Fish overflights in 1988 spotted four of five major species categories: herring, Atlantic menhaden, Atlantic mackerel and baitfish. Three sightings of fish in the nearfield Pilgrim vicinity were made. On May 23, 300,000 pounds of menhaden, and on June 4, 80,000 pounds of menhaden and 50,000 pounds of mackerel were observed near Pilgrim Station, but these occurrences were not reported to regulatory authorities as the Station was in an outage condition witn no thermal plume present. From 1985 - 1988 there have been no observations of pollock.
Benthic Monitoring:
- 1. Six new species of invertebrates were added to the list of biota for PNPS benthic surveys as a result of analysis of the 1988 samples. This brings to 472 the number of invertebrate fauna recorded.
l 2. A notable difference in species richness existed between the Effluent (lower) and Reference stations based on results of the spring 1988 sampling. The reference stations, which have char-atteristically ranked ahead of the Effluent station in species 1
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numbers, appeared more similar to the discharge area in fall 1988 indicating a delayed recovery from PNPS thermal effluent effects.
- 3. Review of overall faunal community structure, via cluster an-alysis, showed that the Effluent Station. had a low degree of similarity compared with the reference stations in spring 1988. Faunal clusterings and algal community overlap values, although somewhat consistent with past observations, show gen-eral recovery of community structure at the Effluent site when compared with reference sites.
- 4. The warm-water species, Gracilaria tikvahiae, decreased in the area of the Effluent station during 1986 and was completely absent in 1987 and 1988, after it had normally colonized in 1985. It was also rare in 1984, indicating a direct relation-ship to the lack of thermal effluent in 1984, 1986, 1987 and <
1988. Additional evidence of PNPS impacts in the Effluent dis-charge zone was the prevalent appearance of the cold-water alga, Laminaria, in the Effluent area during 1984, 1987 and 1988 transect mappings.
- 5. Four observations of the near-shore acute impact zones were performed during this reporting period. Denuded and stunted l zone boundaries were indistinguishable during the 1988 surveys as a result of the PNPS shutdown. These surveys noted greatly decreased near-field impact areas in September and 1
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December although one circulating water pump was consistently in operation the latter half of 1988, resulting in meaningful discharge current flow. Evidence of PNPS-induced scouring im-pacts was most obvious from the results of March and June tran-sect surveys.
Entrainment Monitoring:
- 1. A total of ?' species of fish eggs, and/or larvae were found in the January - December 1988 entrainment collections (18-eggs, 37-larvae).
- 2. Seasonal egg collections for 1988 were dominated by Ameri-can plaice, fourbeard rockling and winter flounder (winter
==rl; spring); mackerel and labrids (late spring - early summer); hake, rockling, labrids and windowpane (late sum-mer - autumn).
- 3. Seasonal larval collections for 1988 were dominated by rock gunnel and sculpin (winter - early spring); winter floun-der, seasnail, Atlantic mackerel and cunner (late spring -
early summer); hakes, windowpane, rockling and cunner (late summter - autumn).
- 4. No lobster larvae were collected in the entrainment samples for 1988, and only nine have been sampled from 1974-1988.
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- 5. In 1988 an estimated 3.532 x 109 fish eggs and 2.581 x 108 fish larvae were entrained at Pilgrim Station, assuming full flow capacity of all seawater pumps. On an . annual basis, eggs were dominated by the' labrid - Limanda group and Atlantic mackerel, and larvae by seasnail, sculpin and rock gunnel.
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- 6. Total numbers of fish larvae collected for similar volumes of water sampled, in spring and summer 1984 and 1987, were lower than for the same periods 1983, 1985, 1986 and 1988.
These results were shown to be related to the fact that both Pilgrim Station circulating water pumps were offline during most of the spring / summer period 1984/1987, but at least one circulating water pump was operating during the majority of this period in other years.
- 7. On two occasions in 1988 high larval densities were recorded in samples as defined by the entrainment contingency plan (" unusually abundant" ichthyoplankton densities). These incidents involved high concentrations of larval sculpin, in February and again in March.
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1 INTRODUCTION l
A. Scope and Objective This is the thirty-third semi-annual report on the status and results of the Environmental Surveillance and Monitoring Program related to the op-eration of Pilgrim Nuclear Power Station (PNPS). The monitoring programs discussed in this report relate specifically to the Cape Cod Bay ecosystem with particular emphasis on the Rocky Point area. This is the twenty-first semi-annual report in accordance with the environmental monitoring and reporting requirements of the PNPS Unit 1 NPDES Permit from the U.S. Environmer.tal Protection Agency (#MA0003557) and Massachusetts Division of Water Pollution Control (#359). A multi-year (1969-1977) report incorporating marine fisheries, benthic, plankton /entrainment and l l
impingement studies was submitted to the NRC in July 1978, as required by j the PNPS Appendix B, Tech. Specs. Programs in these areas have been continued under the PNPS NPDES permit. Amendment #67 (1983) to the PNPS Tech. Specs. deleted Appendix B non-radiological water quality require-ments, as the NRC felt they are covered in the NPDES Permit.
f The objectives of the Environmental Surveillance and Monitoring Program I
are to determine whether the operation of PNPS results in measurable ef-fects on the marine ecology and to evaluate the significance of any ob-
! served effects. If an effect of significance is detected, Boston to ,on Company has committed to take steps to correct or mitigate any adverse situation.
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These studies are guided by the Pilgrim Administrative-Technical Committee (PATC) which was chaired by a member of the Mass. Division of Hater Pollution Control in 1988, and whose membership includes representatives from the University of Massachusetts, the Mass. Division of Hater Pollution Control, the Mass. Division of Marine fisheries, the National Marine Fisheries Service (NOAA), the U.S. Bureau of Sport Fisheries and Hildlife, the U.S Environmental Protection Agency and Boston Edison Company. Copies of the minutes of the Pilgrim Administrative-Technical Committee meetings held during this reporting period are included in Section V.
B. Marine Biota Monitoring
- 1. Marine Fisheries Monitoring A modified version of the marine fisheries monitoring, initiated i" 1981, is being conducted by the Commonwealth of Massachusetts, Division of Marir,e Fisheries (DMF).
The occurrence and distribution of fish around Pilgrim Station and at sites outside the area of water temperature increase are being mon-itored. Pelagic species were sampled using gill net (1 station) col-lectionsc (Figure 1) made at monthly intervals. In 1981, shrimp trawling and haul seining were initiated to provide PNPS impact- 1 related sampling of benthic fish and shore zone fish, respectively.
Shrimp trawling was done twice/ month at 4 stations (Figure 2) and haul seining twice/ month during June - November at 5 stations (Figure 1).
II-2
Monitoring is conducted of local lobster stock catch statistics for areas off Rocky and hanomet Points (Figure 4). Catch statistics are ;
i collected approximately weekly throughout the fishing season {
l (April-October). i A finfish observational' dive program was initiated in June 1978.
SCUBA gear is utilized on biweekly dives f rom May-October (weekly mid-August to mid-September) at 6 stations (Figure 2) in the PNPS thermal plume area.
In 1986, an experimental, lobster pot trawl monitoring effort was initiated to eliminate any biases associated with the collection of lobster stock catch statistics in determining PNPS effects. Ten 5-pot lobster trawls were fished in the thermal plume and control areas around PNPS during 1988 (Figure 3.).
4 Results of the marine fisheries monitoring and impact analysis during the reporting period are presented in Sections IIIA.1 and IIIA.2.
- 2. Benthic Monitoring The benthic monitoring described in this report was conducted by Battelle Ocean Sciences, Duxbury, Massachusetts.
I The benthic flora and fauna were sampled at three locations at depths Quantitative (rock substratum) samples of 10 feet (MLW) (Figure 1).
were collected, and the dominant flora and fauna in each plot were recorded. Sampling was conducted two times per year (March and II-3
September) to determine blotic changes, if any. Transect sampling off the discharge canal to determine the extent of the denuded and stunted zones was conducted four times a year (March, June, Setpember and December). Results of the benthic surveys and impact analysis during this period are discussed in Sections IIIB.1 and IIIB.2.
- 3. Plankton Monitoring Marine Research, Inc. (MRI) of Falmouth, Massachusetts, has been monitoring entrainment in Pilgrim Station cooling water of fish eggs and larvae, and lobster larvae (from 1973-'1975 phytoplankton and zooplankton were also studied). Figure 5 shows the entrainment contingency sampling station locations to be sampled should the numbers of eggs / larvae entrained greatly exceed recorded historical averages. Information generated through this monitoring has been utilized to make periodic modifications in the sampling program to more efficiently address the question of the effects of entrainment.
These modificattoris have been developed by the contractor, and reviewed and approved by the Pilgrim A-T Committee on the basis of ;
i program results. Plankton monitoring in 1988 emphasized consideration of ichthyoplankton entrainment. Results of the ichthy-oplankton entrainment monitoring and impact analysis for this re-porting period are discussed in Sections IIIC.1 and IIIC.2.
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- 4. Impingement Monitoring The Pilgrim Station I impingement monitoring and survival program i speclates quantifies and determines viability of the organisms carried cnto the four intake traveling screens. Since January 1979, Marine Research, Inc. has been conducting impingement sampling with resuits being reported on by Boston Edison Company.
A new screen wash sluiceway system was installed at Pilgrim in 1979 at a total cost of approximately $150,000. This new sluiceway !.ystem j was required by the U.S. Environmental Protection Agency and the Mass. Division of Water Pollution Control as a part of NPDES Permit
- MA0003557. Special fish survival studies conducted from 1980-1983 to determine its effectiveness in protecting marine life were ter-minated in 1984, and a final report on them appears in Marine Ecology Semi-Annual Report #23.
Results of the impingement monitoring and survival program, as well as impact analysis, for this reporting period are discussed in l
Section IIID.
l C. Fish Surveillance Studies March - November, weekly fish spotting overflights were conducted as part f
of a continuing effort to monitor the times when large concentrations of fish might be expected in the Pilgrim vicinity. Regularly from May-October since 1978, dive inspections have been conducted of the Pilgrim ;
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l discharge canal in order to evaluate fish barrier net durability, and effectiveness in excluding fishes from the discharge canal.
The annual summary report on fish overflights for 1988 is presented in Section IVA. Barrier net inspections were not performed in 1988 as Pilgrim Station was in an outage the whole year, and the net has been removed from the discharge canal since August, 1986.
D. . Station Operation History The daily average, reactor thermal power levels from January through December, 1983-1988 are shown in Figure 6. As can be seen, PNPS was in an outage during the 1988 reporting period; however, environmental mon-itoring programs were performed to obtain control data for impact com-parison with past and future high operational years.
E. 1989 Environmental Programs A planning schedule bar chart for 1989 environmental monitoring programs related to the operation of Pilgrim Station, showing task activities and milestones from December 1988 - June 1990, is included as Figure 7.
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ANNUAL REPORT ON MONITORING TO ASSESS IMPACT OF
' PILGRIM NUCLEAR POWER STATION ON MARINE FISHERIES RESOURCES OF WESTERN CAPE COD BAY (CH AR ATERIZATION OF THE FISHERIES RESOURCES)
Project Report No. 46 (January-December,1988) , (Volume 1 of 2) By Robert P. Lawton, Brian C. Kelly, Vincent J. Malkoski, and Mando Borgatti l i l 1 l-l April 1,1989 l Massachusetts Department of Fisheries, Wildlife, and Environmental Law Enforcement Division of Marine Fisheries 100 Cambridre Street Boston, Massach esetts 02202
1 TABLE OF CONTENTS Section - Eag.g i I. EXECUTIVE
SUMMARY
1 II. INTRODUCTION 2 l i III. METHODS AND MATERIALS 3 IV. RESULTS AND DISCUSSION 5 A. Hydrography 5
- 1. Water Temperature 5
- 2. Sallalty 6 B. Fisheries - Lobster 6
- 1. Commercial Lobster Pot-Catch Fishery 6
- 2. Research Lobster Trap Fishery 7 C. Fisherles - Finfish 9
- 1. Nearshore Benthic Finfish 11 1
1 2. Pelagic and Benthl-Pelagic Fishes 15
- 3. Shorerone Fishes 17 l
1
- 4. Underwater Finfish Observations 21
- 5. Sportfishing 23 V. HIGHLIGHTS 25 VI. ACKNOWLEDGEMENTS 28 VII. LITERATURE CITED 29 1 .j L
l l l 11
LIST OF TABLES > Table f.att
- 1. Checklist of finfish species (following classification of Robins 9 et al.1980) collected or obserwed in the adjacent waters of Pilgrim Station,1988.
- 2. Expanded catch and percent composition of groundfish captured by 11 bottom trawling at four stations in the vicinity of Pilgrim Station, January-December,1988.
- 3. Bottom trawl catch data for dominant groundfish in the vicirity of 13 Pilgrim Station, January-December,1988.
- 4. Number and percentage composition of selected finfish species captured 15 by gillnet (7 panels of 3.8-15.2 cm mesh)in the vicinity of Pilgrim Nuclear Power Station, January-December,1988.
- 5. Shore-zone fishes captured by haul seine at four stations in the vicinity 18 of Pilgrim Nuclear Power Station, June-November,1988.
- 6. Shore-zone fishes captured by foot-seine at five stations in the environs 21 of Pilgrim Nuclear Power Stat 80n, June-November,1988.
). 7. Abundance and distribution of finfish species observed during underwater 22 observations, May-October,1988. i
'l I
111
LIST OF FIGURES Fleure fagt
- 1. Location of Marine Fisherles sampling areas for trawl, slll net, 4 haul seine, lobster, dive, and sportfish surveys in the Pilgrim study area.
- 2. Bottom water temperatures (ambient) recorded in Warren Cove during. 5:
spring, 1983-1988.
- 3. Monthly commercial lobster catch per trap-haul la the Pilgrim area,1988. 6
- 4. Size distribution of lobster captured in the research trap study off 8 Pilgrim Station in 1986,1987, and 1988.
5.' Spring Resource Assessment Survey winter flounder abundance in Stratum 12 25 (less than 9.1m) la Cape Cod Bay, 1982-1988.
- 6. Seasonal mean trawl catch rates for winter flounder by station in 12 Pilgrim area,1988.
- 7. Spring Resource Assessment Survey little skate abundance in Stratum 25 13 (less than 9.1 m)la Cape Cod Bay, 1982-1988.
- 8. Seasonal mean trawl catch rate for little skate by station in 14 Pilgrim area,1988.
14
~
- 9. Spring Resource Assessment Survey windowpane abundance in Stratum 25 (less than 9.1 m) in Cape Cod Bay, 1982-1988.
- 10. Seasonal mean trawl catch rate for windowpane by station in 14 Pilgrim area,1988.
- 11. Indices of relative abundance (CPUE) for pooled finfish species 16 captured near Pilgrim Station based on standardized gillnet gear and procedures, 1971-1988.
- 12. Indices of relative abundance (CPUE) for Atlantic herring captured 16 near Pilgrim Station based on standardized gillnet gear and procedures, 1971-1988.
- 13. Indices of relative abundance (CPUE) for pollock captured near Pilgrim 16 Station based on standardized gillnet gear and procedures, 1971-1988.
- 14. Indices of relative abundance (CPUE) for cunner captured near Pilgrim 17 Station based on standardized gillnet gear and procedures, 1971-1988.
l iv l (
I I I. EXECUTIVE
SUMMARY
u A modified version of mar!ne fisheries monitoring, initiated in 1981, was conducted by i the Massachusetts Dielslon of Marine Fisherles in 1988. The occurrence, distribution, and relative abundance of finfish and lobster were monitored according to standardized sampling i schemes to identify trends and relationships la the sampling data collected from the study area over time. We directed most of our efforts to commercially and recreationally important fisherles resources. Nearshore bottom trawling and haul setning sampled groundfish and shorezone fish, respectively, while an experimental gillnet monitored pelagic fish. Monitoring of the local commerciallobster stock catch statistics was conducted during the lashore lobster season. Experimentallobster trapping, also conducted, eliminated many biases associated with the collection of commerciallobster catch statistics. A finfish observational dive program and a sportfishing creel survey rounded out investigations. Catch rates in the Pilgrim area declined from 1987 to 1988 for the top three groundfish (winter flounder, little skate, and windowpane) trawled. The gill net catch of cunner was about the same while pollock catch doubled from last year. The seine catch rates of Atlantic silverside and blueback herring were down from last year. Overall few fish were sighted during the diving study. Sportfish catches were at their lowest level relative to past records. t l l
II. IN_TRODUCTION
- Environmental monitoring was conducted in 1988 by the Massachusetts Division of Marine Fisheries (DMF) in an ongoing effort to assess plant-related impact of the Pilgrim Nuclear Power Station (PNPS) on marine resources in western Cape Cod Bay, under Purchase Order No. 65216 to Boston Edison Company (BECo). Data on the occurrence, distribution, and relative abundance of finfish and lobster were collected following a standardized sampling scheme. Analyses included measurements, enumerators, percentages, and Indices which were used to identify trends and relationships in the data for the study area as a whole. Volume 1 is a characterization of fisherles' resources in the Pilgrim area.
This report highlights pertinent findings in a nwdified overview. Detailed analyses including sta:isticalinformation and supportive data with synoptic results are available from the Division of Marine Fisherles upon request. Only essentialluformation is presented in order that the volume of written material be substantially reduced. The reporting of environmental studies at PNPS has evolved in steps beginning as a progress report which included much raw data growing to an exhaustive scientific report, and finally being reduced into the present format. Our latent is to condense subject matter but maintain clarity of technical data reporting and laterpretation. Hopefully the end result is a more readable report. i l
)
l
III. METIIODS AND MATERI ALS For a complete description of the sampling design including techniques and gear / equipment, the reader is referred to Semi-Annual Report No. 31 (January-December 1987): section Ill.A.1; pages 3-13 in the report series entitled Marine Ecolocv Studies Related 1 I Jo Operation of Pilcrim Station published by Boston Edison Company. The general sampling area is depleted in Figure 1 while figures of specific sampling statina locations appear in section II of this report. The econornic importence of the Amerlean lobster (Homarus gtmericanus) fishery in the vicinity of Pilgrim Nuclear Power Station has dictated a sampling program of commercial pot j catches. The study's objectives are to determine w hether power plant operation has measurably l 4 affected the local lobster population and fishery ac well as provide additional information i on the lobster population of western Cape Cod Bay. An index of harvest was obtained from biweekly sampling the catch of a local commercial lobsterman. An outgrowth of this work is a controlled experimentallobr,ter study which was implemented in June 1986 to better measure the impact of the thermal discharge from Pilgrim Station on the local lobster population / fishery. By conducting standardized research trap fishing, we gained control o+er the selection of fishing grounds, gear, and distribution of effort. Qualitative and quantitative sampling was conducted of the finfish community in the vicinity of the power plant with the emphasis on commercial, recreational, and forage stocks. Studies have been scoped to detect changes in occurrence, distribution, behavior, and population abundance of dominant finfish species. To monitor nearshore groundfish in the I Pilgrim area, we conducted small vessel (Sm) bottom trawling. Via gill net sampling, we monitored pelagic and bethl-pelagic fish. To countervail gear seleciliity in bottom trawling and gill netting, haul seining was conducted at intertidal and shallow subtidal sites. This year all seining was done at i 2 hours of low tide, and station 6 was deleted herause an alteration l In substrate presented us from seining there. An underweter observational program provided { direct visual data on fish numbers, sizes, location, behastor, and condition just outside the discharge canal; invertebrates and algae were also monitored for gross effects. Sportfishing l at Pilgrim Station's Shorefront recreational area was monitored by Boston Edison Company l l _3_
g. l :, i s' f i .' public relations personnel at the water front in a cooperative effort with us to maintain a database on the recreational fishery of the area.
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l I IV. RESULTS AND DISCUSSION ] I A. HYDROGRAPHY j
- 1. Water temperature In the inshore waters of western Cape Cod Bay, ambient surface water temperatures have ranged from - 1 C recorded in mid-winter to 23 C in mid-summer, while bottom temperatures of -1 C (mid-winter) to 21 C (late summer) have been the bounding limits (Lawton et al.1983). Water begins warming in March or April (March in 1988), and a -
thermocline normally forms in June at a depth of between 5 and 10 m. Surface to bottom temperature differentials have ranged from a low of 0.5 to a high of 4.7 C. The highest Individual surface temperature (23 C) was recorded in August of 1973 and 1984. Wa ter' temperatures during spring and summer were higher in the estuary of Plymouth, Kingston, Duxbury Bay, warming to about 25 C in the shallows during summer. Over the last six years (1983-1988), water temperatures in the Pilgrim area were highest in 1983 and 1985,latermediate in 1987 and, on the whole, temperatures were somewhat lower in 1986 and 1988. Most noteworthy was the markedly lower temperature regime during all seasons of 1984. Temoeraw c Plotting bottom water temperatures 12 - ,-D- ..# j for spring was insightful (Figure 2). 7 Cooler springs are evident for 1984 3 o-f and 1987. It appears that cooler e- ; spring temperatures in those years 4
,,l , j,, ' ,,, ,j,l ,,3, ,, ,3 ,,3g resulted in lower commercial lobster
- 1983 ~4- 1994 -*-- 1985 catch rates in the Pilgrim area + iose - 1987 -+- 1988 which is related to reduced molt probability and resultant lower figure 2. Bottom water temperatures (ambient) recorded in Warren Cove recruitment to legal size, during spring, 1983-1988.
) -s-
- 2. Salinity Salinities in the study area were high, ranging from 28-35 '/,. The average was 31
*/,. There is minimal influence of fresh water drainage from watersheds. Efficient tidal exchange in Cape Cod Bay accounts for its waters exhibiting little salinity variation f rom those 'of Massachusetts Bay and the Gulf of Maine (Davis 1984).
l' B. FISHERIES - LOBSTER
- 1. Commercial lobster not-catch fisherv Monitoring the commercial American lobster (flomarus americanus) fishery in 1988 in the Pilgrim study area began in May and concluded in October. Lobster catch statistics and biological data (i.e., carapace length - CL, sex, shell hardness) were collected for the six month investigation during 11 sampling trips aboard a commerciallobster boat. Data were recorded on 2,237 lobster taken from 1,409 lobster pot-hauls.
Overall catch per pot for all lobster (comprised of legal - CL 1 81.8 mm - and sublegal lobster) for the Pilgrim area was 1.6, up very slightly from last year's CPUE of 1.5. Twenty-four percent (542) of the total catch were legal lobster for an annual legal catch rate of 0.38
' lobster / trap-haul, a small increase from last year's value of 0.33. The lowest monthly legal catch rate occurred in October (0.26), and the highest (0.67) in August (Figure 3 ).
The monthly catch rate of both sublegal MONTHLY LOBSTER CPUE and legal lobster paralleled that of the overall CATCH PER TRAP HAUL lobster CPUE. The ratio of sublegal to legal A lobster was 3.1:1. eo- F-r... , -. Females comprised 49% of the annual - catch. Monthly sex ratios were stable at 1:1. e g g - gJ There were 23 origerous (egg-carrying) females " " #^ ^a $5' "' i
,g sampled (2.1% of the female catch), of which 13 ~ * ^' *"8'E" N' 88 8" ^
(1.2% of all females and 56% of all oilgerous Figure 3. Monthly commercial l lobster catch per trap-haul females) were sublegal. The overall percentage of in the Pilgrim area, 1988. ovigerous females was greatest in early fall l
(September at 15.5% and -October at 4.0%) and lowest in summer (0.4% in July). The 1 l seasonality of origerous females is typical of the two-year reproductive cycle of the American i lobster (Alken and Waddy 1982). Female lobster generally breed af ter the summer molt, but
. do not extrude fertillred eggs until fall of the following year. The eggs are then carried I throughout the winter and hatch out in the spring,
- 2. Research lobster tran fishine From 8 June through 30 September 1988, we conducted research lobster trap fishing for the third year in the discharge area of Pilgrim Station and at two reference areas n6rby. j i
In 50 sampling days,6,456 lobster were captured from 2,457 trap-hauls. Sample collections were comprised of 85% sublegals (i.e., <S1.8 mm carapace length-CL) and 15% legals (i.e, t 81.8 mm CL). In 1988, the legal lobster size in Massachusetts was increased from E 81 mm CL to a 81.8 mm CL. The increase in gauge size resulted in a shif t of 4% in the 1988 catch, where 4% of the catch that would have been legal in 1987 were sublegal in 1988. The ratio of sublegal to legal in the catch was 5.8:1. ) The number of lobster (pooled for legal and sublegal) caught per trap-haul ranged from 0 to 13, with sublegals ranging from 0 to 11 per trap-haul and legals,0 to 6. In 16% (393 traps) of the trap-hauls, no lobster were caught. The overall mean catch-per-trap-haul (CTH)in the study area for lobster of all stres and sexes combined was 2.6 in 1988; this is up from 1987 (2.1) I l and 1986 (1.2). The mean CTH of sublegals was 2.2 - up somewhat from 1987 (1.9); whlie CTH of legals averaged 0.4 in 1988 and 0.3 in 1987. Males comprised 52% of the research catch as was the case last year. Conversely, females have predominated in the commerciallobster catches sampled in the deeper waters of I western Cape Cod Bay (Lawton et al.1987). Our finding of a higher percentage of male lobster in the inshore catch agrees with results of work in Long Isind Sound where Briggs and 1 Muschacke (1979) found males outnumbering females in shoa; water catches. We captured only 22 origerous (egg-bearine.) females /or 0.7% of the total catch of females. The percent females otigeroas in commercial catches of the area was 2.1%. The proportion of ovigerous females in trap catches has been higher in Burrards Bay, constituting l
up to 14% of the catch there; whereas,in Cape Cod Bay the proportion generally has been below 1% (Collings et al.1983). The percentage of culls,i.e., lobster with missing and/or regenerating claw (s), sampled in research lobster fishing in 1988 was 23%. In 1987, cull rates were 20% in research catches and 21.4% in commercial catches of the area. Cull rate generally has increased during this decade in the Pilgrim area as fishing effort has Intensified. Carapace lengths of lobster sampled in research trap catches ranged from 41 to 121 mm, averaging 74.9 mm, which is 2 mm greater than means for the last 2 years. A length-frequency histogram of all lobster sampled in research catches for 1986-1988 was compiled (Figure 4). The effects of availability, vulnerability, and high rate of exploitation are manifested in this histogram of our catches. The stepwise lucrease in lobster catch from 50 to 75 or 76 mm CL suggests that at the latter size, lobster are fully vulnerable to our gear; the modal length was 80 mm CL. Reduced catches below this size probably result from gear selectivity (escapement) and the reduced availability of small lobster ( <50 mm CL). The marked reduction in numbers of lobster of just legal size and greater reflects the latencIve fishery, commercial and recreational, of the area. Relative Frequency (%)
/
10-a ~a 5-f [L 1 i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i . 64'N4. .W 0 . . . . 55 60 65 70 75 80 85 90 95 100 50 Carapace Length (mm) In 1 mm increments i 11986 E 1987 E 1988 Figure 4. Size distribution of lobster captured in the research trso study of f Pilgrim Station in 1986.1987, and 1988. 1 s C. FISHERIES - FINFISII A species check list (Robins et al.1980) with scientific names is found in Table 1, which includes all fish observed or collected by all gear types in the Pilgrim study area in 1988. 1 Table 1. Checklist of finfish srecies (following classification of Robins et al.1980) l collected or observed in the adjacent waters of Pilgrim Station,1988. ] Class: Chondrichthyes Order: Squaliformes Family: Carcherinidae - requiem sharks Mustetus san 11 (Mitchttt) - smooth dogfish Family: Squalidae - dogfish sharks 1 Saustus acenthies (Linnaeus) - spiny dogfish Order Rajlformes Family: Rajidee - skates Baja erinaces (Mitchill) - tittle skate Ella ocettate (Mitchill) - Winter skate Ctess: osteichthyes' Order: Clupelformes ; Family: Clupeidee - herrings 1 8.l211 mestivalis (Mitchitt) - blueback herring 8t21A oseudoherennus (Wilson) - alewife erevoortie tYrennus (Letrobe) - Atlantic menheden E13333 herenaus parennus (Linnaeus) - Atlantic herring Family: Engraulldne - anchovies 8,nghgg mitchitti (Valenciennes) bay anchovy Orderi Salmoniformes Family: Generldne - smelts Osmerus grsigx, (Mitchill) - rainbow smelt Orders Gediformes Family: Gedidae - codfishes fea5lWE morhur (Linnaeus) - Atlantic cod Merluccius bilineeris (Mitchill) silver hake gj,gIpgggiyg 153Egs! (Walbem) Atlantic toscod Pottschius virens (Linneous) pollock Urochysis tenuis (Mitchitt) White hake Family: Zoarcidae - eelpouts Macrozoarces americenus (Bloch and Schneider) - ocean pout Order Gasterostelformes i Family: Gesterosteidae - stickleback I Gasterosteus seuleatus (Linneous) spine stickleback Femily: Syngnathidae - pipefishes and seahorses ! I Synenethus fuscus (Storer) - northern pipefish orders AtherInlformes Family: Atherinidae - silversides )- Menidio menit;ff e (Linnaeus) - Atlantic silverside J-Family: Cyprinodontidae - killifishes Furdutus molelf s (Walbem) striped kittifish Fundulus heteroctitus (Linnaeus) - manichog j .,.
i-Orders Percifones Family: Percichthyldne tosperate besses
!!g,tgng saxatitis (Walbeum) - striped bass Family: Serrenidae ses besses centraoristes striste (Linnaeus) - black sea bass Family: Pomatomidae - bluefishes Pomatomus saltatrix (Linnaeus) - bluefish Family: Secobridae - mockerets and tunes Sconber scambrus (Linnaeus) Atlantic meckeret Family: Speridae - porgles Stenotomus chrysops (Linnaeus) - scup Family: Labridae - wresses Tautone sch],1 (Linnaeus) - toutog -
Teutonotebrus odspersus (Walbem) - cunner Family: Mugilldee ,
!!6gL.L I cechatus (Linneeus) - striped mullet Family: Pholidae g e nets th2111 nunnettus (Linnaeus) rock gunnel Family: Stremoteldee - butterfishes Peorilus tef acenthus (Peck) - butterfish Family: Triglidae - searobins Prionotus carolinus (Linnaeus) - nothern Jearobin Family: Cottidae - sculpins Hamitrioterus americanus (Gmelln) - sea reven i Myoxocechatus eeneous (Mitchitt) - grubby Myogocechstus octodecomspinosus (Mitchill) longhorn sculpin Mvonocechstus scorpius (Linnaeus) shorthorn sculpin i
Family: Cyclopteridae - luupfishes and shellfishes cvetooterus tunous (Linnaeus) - ltspfish Liperf s attenticus (Jorden and Evermann) - seasnall . I Fami!y: Anunodytidee - send iences ! Anmodytes m order Pleuronectiformes . Family: Bothidae - lefteye flounders 1 Paratichthys dentatus (Linnaeus) - summer flourder (fluke) Paratichthys oblongus (Mitchill) - fourspot flouixier Scochthalmus eauosus (Mitchill) - Windowpane l Family: Pleuronectidae - righteye flomders Liesnde ferruninea (Storer) - yellowtait flounder Pseudocteuronectes americanus (Walbem) - Winter flounder q Order: Lophilformes Family: Lophildee goosefishes Lochius americanus (Valenciennes) - goosefish
' Order: Tetroodontiforses Family: Tetraodontidae - puffers Schoeroides moeutetus (Block and Schneider) northern puffer i
- 1. Nearshore benthic finfish i
We completed 110 bottom trawls in the study area in 1988. A total of 1,097 fish, representing 31 species, was collected (Table 2). Three groundfish - winter flounder, little skate, and windov. pane - comprised 79% of the catch.The average catch per tow (our measure of catch-per-unit-effort, or CPUE) for the study area (all species and stations pooled) was 10.0, a decline of over 56% from last year.The intake embayment (Station 6) and the Priscilla
' Beach site (Station 4) yleided the highest CPUI's (pooled species) of 13.8 and 10.7, respectively.
1 Table 2. Expanded catch and percent composition of groundfish captured by bottom trawling at four stations in the vicinity of Pilgrim Station, January-Decenber,1988. Station 1 3 4 6 Warren Pilgrim Priscilla Pilgrim Percent of Species Cove Discharge Beach Intake Totals total catch Winter flounder 161.4 N0554 165.9 (1N[d;f 564.7 51.4 Little skete 31.8 '156.3% 80.3 L 32.6 : 201.0 18.3 Windowpene 34.2 522.5 % 31.5 'l: 14'. 4 i 102.7 9.4 Yellowtail flounder 1.0 19.72 25.2 ::4.8 % 40.7 3.7 Atlantic silverside 7.0 ? 9.2 ::l 6.0 112.41 34.5 3.2 Cunner 23.5 3 2.3 l 0.0 Tc7.0 ? 32.8 3.0 White hake 0.0 iL1.4% 7.0 bl.8 ? 17.1 1.6 Atlantic cod 2.0 18.5% 2.0 s3.2 ': 15.8 1.4 Butterfish 9.8 J 0.0;;i 1.0 s0.03 10.8 1.0 Atlantictomep 0.0 iii.01 2.0 F 8.4 t 11.4 1.0 other species 23.3 , 4 9.7/: 10.2 .: 22.0
- 65.2 6.0 Number of species 17 R17i 17 M 31 Ntaber of tows 34 .? 27:t . . 31 (186 110 Total fish 293.9 i224'.02 331.1 1247.69 1096.6 Catch per tow 8.6 + 4.3 :;; 10.7 z13.5::; 10.0 Percent cf catch 26.8 $ 20.4 J 30.2 ;.22.6 I
Catch rates were expanded for tows less than the standard 15-minute duration. 2 Represents pooled totals from 21 species of low catch abundance. Shaded columns are data collected at surveillance stations. Winter flounder ! Winter flounder again ranked first in catch (51%; all stations pooled) for the study area l and was numerically dominant at each station. The mean CPUE for the study area declined for the second consecutive year from 7.7 (1987) to 5.1 winter flounder / tow in 1988. The index of winter flounder abundance (mean number of fish per tow) for water < 9.1 meters deep in f Cape Cod Bay generated from the coastal spring bottom trawl survey, conducted by the f
Reurce Assessment Project of the Spring Survey Abundance: Winter Flounder Massachusetts Division of Marine Fisheries, Stratum 25 - Cape Cod Bay a i s o u n d e r w e n t 120 "*# " 100 a substantial decline this year (Figure 5). , 80-The Intake again ranked first in , 60-
~'
winter flounder catch with an annual mean ,g. CPUE of 7.4; however, this is down 50% 20 from last year. The Discharge site (Station 1982 1983 1984 1985 1988 1987 1988
- 3) had the lowest winter flounder catch ure ng s uce Assessment index of 3.8 - a decline of 48% from 1987. Survey winter flounder abundance Annual mean CPUE at the other two stations in Stratum 25 (less than 9.1 meters) in Cape Cod Bay, 1982-1988.
(Warren Cove and Priscilla Beach) declined slightly this year. Seasonal trawl catch rates of winter Winter flounder seasonal catch / tow flounder (Figure 6) followed a pattern of lowest Nuvoen or riss/ Tow 22 catches in winter, moderate catches in spring, [ uns srcon i+crEncucc g
,3 t"2 STAh0N MSCHAAGE =
slightly depressed summer catches with the excep- u. gum SIMlON 4-AErERENCE g 12- 8 STA40N 64NTAKE 3 tion of the very high CPUE in the Intake, io- g
- e. g; = g_
followed by generally declining catches in the e. psi = g p- g $ 4- e ; s .
!y a a a i fall.The markedly high summer catch rate in the 'E-o b
SPRING b k II!! SUMMER b FALL 5 WINTE R Intake was derived from limited sampling data SEASON (only 2 tows), as lobster gear precluded comple. Figure 6. Seasonal mean trawl catch ratas for winter founder tion of other tows of the minimally acceptable by station in Pilgrim area, 1988. duration of 10 minutes.The smaller annual mean size of winter flounder at this site (24.3 cm; Table 3) reflects the preponderance of smaller flounder caught here. l 1
Table 3. Bottom trawl catch data for dominant groundfish in the vicinity of Pilgrim I station, January-December, 1988. Winter Little flounder skate Windowpene STATION.1 Mean catch / tow 4.7 0.9 1.0 Mean size (cm) 30.2 42.2 24.1 size range (cm) 14-44 25 55 10-33
-STAT!aN3i . . . . . ......[
- Neon catch / foil fli 3 18if: . 52 Nil ..k O$
Noon sIse (cm)i. f 29.83 $33,3 :! f2247: [streirangel(ce)f6 s117 41) g:4Q7-52.!j 615t30; STATION 4 Mean catch / tow 5.4 2.6 1.0 Mean size (cm) 31.1 33.3 23.9 Size range (cm) 11-46 20-52 13-28
? STATimi 65
.Nean catch / tow!!: ,f 73 3: M3j jfD.'8 s Mean tize :(cm) lit. f24.3i i34.31 ..;;23.8
! size:rangetem)( iil3p43j;: i:;23:50 ;! 11E33 I
catch rates were expanded for tows less than the standard 15-minute duration. Shaded rows are data collected at surveillance stations. Little skate Little skate ranked second, comprising 18% Spring Survey Abundance:Little Skate of the overall catch. Mean annual catch per Stratum 25 - Cape Cod Bay 120 m declined 74% to 1.8 as compared with 7.0 in 8o. 1987.The spring Resource Assessment Project l Bo -- abundance index for little skate in Cape Cod 4o Bay waters of less than 9.1 m increased to-o . kuut7 slightly in 1988 (Figure 7). 1982 1983 1984 1985 1986 1987 1988 Year Unlike preceding years, this species was not figure 7. Spring Resource numerically dominant at any of the stations. Assessment Survey little skate ) abundance in Stratum 25 (less The highest annual station catch ratt of 2.6 I than 9.1 m) in Cape Cod Bay, 1982-1988. little skate / tow occurred at the Priscilla ) .
Beach site, which is down 61% from last year; Warren Cove had the lowest annual CPUE of 0.9, which represents an 84% decline from 1987. Catch rates for little skate exhibited a similar overall seasonal pattern at all stations: very low values in winter, peak catches in spring, precipitous declines la summer, followed by Little skate seasonal catch / tow further declines in fall (Figure 8). The highest , S i
)=
catch rate was obtained in the Intake (9.7) in e-e. GE
=prias- ;: ;s p . . . _ . . . _
ca.w...+ , Wind owna ne t !m=M as .- ~ ean= 4-g g;g e .-,- -. Windowpane was third overall in the trawl [ }j j catch (9%) for the sixth consecutive year. Mean [ - WINTER 0N
$PRINO SUMMER
! -n F4LL annual CPUE for all stations combined declined 76% from 3.7 windowpane / tow in 1987 to 0.9 this Figure 8. Seasonal mean trawl catch rate for little skate year; this is the second consecutive annual decline. by station in Pilgrim area, 1988.
Conversely, the spring Resource Assessment project abundance index for windowpane increased in 1988 (Figure 9). l Spring Survey Abundance: Windowpane Windowpane seasonal catch / tow Stratum 25 - Cape Cod Bay NUMBEA OF FISH / TOW
,, Fish / tow 4-so f 3 @
a
- s. swion mernatact is- : c3 sw on eesc>.4aos <
, y 5 BFJ swioN 4 4EFERENCE
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SUMMER _J!!!L FALL f Wet 1943 1964 1966 9 69 1887 1944 Year SEASON Figure 9. Spring Resource Figure 10. Seasonal mean trawl Assessment Survey windowpane catch rates for windowpane by abundance in Stratum 25 (less statio~ in Pilgrim area, 1988. ( than 9.1 m) in Cape Cod Bay, j 1982-1988. l I I Annual CPUE for windowpane varbd little amongst the sites, ranging from 0.8 - 1.0. l Warren Cove had the greatest CPUE for the sixth consecutive year. Seasonally, windowpane were nearly absent from winter groundfish catches (Figure 10). Catches were by far the I highest in spring, followed by reduced levels in summer and f all. Yellowtail flounder Yellowtail flounder ranked fourth comprising 4% of the total catch.This flatfish was most abundant at Priscilla Beach. The annual mean CPUE of 0.4 for all stations pooled represents a 33% decilise from last year. I 2. Pelaric and benthi-nelacle fishes Gill-net collections from 13 overnight sets in 1988 yielded 29 finfish species totalling 3620 Individuals (Table 4). No sampling was performed during April and December due to inclement weather. Two sets were made during the months of May, June, and October. Table 4. Nwber and percentage composition of selected finfish species captured by gill net (7 penets of 3 815.2 cm mesh) in the vicinity of Pilgrim Nuclear Power Station, January December, 1988. Percent of species Wmber total catch I Atlantic herring 1742 48.1 Potiock 1184 32.7 Cunner 220 6.1 Other* 474 13.1 Total 29 species 3,620
*The remaining species were not found in abundance.
I Annual mean catch per unit effort (CPUE) for pooled species (5 panels of 3.8-8.9 cm mesh) was 241.9 fish / set (Figure 11), the highest recorded for the study since 1977 and a notable increase over last year. A marked increase in catch abundance of Atlantic herring and pollock as compared with 1987 catches, contributed to the higher overall catch rate. The dominant species were Atlantic herring, comprising 48% of the total catch, pollock (33%), and cunner (6%). These three species have dominated the gill-net hierarchy since I
- b. .
1971, with the exception of 1985, when the relative - sa-.
,~~
abundance of Atlantic herring was unusually low. ,,..
~
Atlantic herrinc Most of the herring catch (86%) came from two sets, one in February and one in November. A e,,,,,,,,,,,,,,,,.,,,,,,,,,,,,,,,,,,,, traditional dominant in our gill-net collections, Figure 11. Indices of relative abundance (CPUE) for pooled Atlantic herring were all but absent from project finfish species captured near Pilgrim Station based catches in 1985 (5 fish), with continued low abundance on standardized gillnet and procedures, 1971-through 1987 (Figure 12). A marked resurgence in , 1988 (1742 fish), is indicative of their highly migratory nature and wide variation in local
~ ~ ' ' ~ ~ ' "
abundance (Bigelow and Schroeder 1953). ; Pollock - A comparison of annual CPUE values of pollock " reveals that relative abundance in 1988 greatly " increased from 1987 and was at its highest level since Figure 12. Indices of relative 1981 (Figure 13). However, as with Atlantic herring, abundance (CPUE) for Atlantic herring captured pollock are subject to wide fluctuations in local near Pilgrim Station based on standardized gillnet abundance. gear and procedures, 1971- l 1988. ! Cunner ; CPUE for cunner in 1988 was 16.9 fish / set. . - ~ As seen in Figure 14, relative abundance of cunner in a.O . the Pilgrim area has experienced a marked downward ! trend since 1984. Also noted by project divers, the l decline perhaps is partly due to mortality from *,,,,,.4.,,,,,,,,, , , . , recreational fishing pressure over the years at Pilgrim figure 13. Indices of relative bundance (CPUE) for Shorefront. pollock captued near Pilgrim Station based on standardized gillnet gear and procedures, 1971-1988. l
{ Other Snecies The remaining species captured by gill net in ,o "~ a"* *
- 1988 were taken in relatively low numbers, with no .o-single species comprising more than 2% of the total a-catch. Some, such as tautog, experienced increased relative abundance. Others, such as striped bass and bluefish, have a known affinity for the thermal '""""""""g '" '8 m * ** * *' "
effluent (Lawton et al.1986); their numbers are Figure H. Indices of relative a a ce W Q h cunnu generally low in the Pilgrim area when the plant is captured near Pilgrim not operational. The mejority of these species are Station based on standardized gillnet gear captured only sporadically and never have occupied and procedures, 1971-1988. positions of dominance in gill-net records.
- 3. Shore-rone fishes A total of 16,815 finfish representing 21 species was captured in the 45.7 meter haul seines from June-November,1988 (Table 5). Five taxa - Atlantic silverside, sand lance spp.,
blueback herring, winter flounder, and Atlantic menhaden - comprised 98% of the overall catch. The mean catch of finflah per standard seine set (168.2) for all stations and species pooled decreased 54% from 1987. Substantial decreases in catch rates (pooled stations) of several of the dominant shore-zone finfish species - Atlantic silverside, blueback herring, and alewife - contributed to the overall decline. In contrast, o>erall winter flounder and sand lance spp. catch rates increased slightly from last year. Station catch rates for pooled species decreased at three sites from last year, with declines at Manomet Point (15%),the Pilgrim Intake Beach (46%), and Long Point (73%). 1 { Conversely, catch rate Ircreased at Warren Cove by 36%, primarily due to latge catches of Atlantic silverside in September. Seine catches were highest overall at Long Point where 36% of the total was obtained (Table 5).This was primarily a result of the abundance of sliterside there. Overall, catches in 1988 were again relatively low at Manomet Point. In terms of total fish caught, catch rate, and
species diversity, the Intake station was for the third consecutive year most similar to Long Point, an estuarine location. Catches at the exposed coastal beach stations at Masomet Point and Warren Cove reflected the lack of cover.The catch rate at Warren Cove was anomalously higher relative to the previous two years. Table 5. Shore :one fishes captured by haut seine at four stations in the vicinity of Pilgrim Nuclear Power Station, June + November,1988. Station 2 3 4 5 Warren PilgrigManometLong Total Percent species cove Intake Point Point Number of total Atlantic silverside 4192 6061h 1087 5830 12170 72.i Sand lance spp. 0 12948s 0 3 2951 '17.6 Blueback herring 1 ' g 5881 118 0 707 4.2 Winter flomder 36 2:354 i 48 58 496 3.0 Atlanticmenhf 4 :> 122 3 5 1 132 0.8 other species 15 j.210j 28 106 359 2.0 Total rumber of fish 4248 $52831 1286 5998 16815 Nunber of seta 24 3 261:. 24 26 100 Catch / set 177.0!f203.21 53.6 230.7 168.2 Total nLaber species 8 11 17 21 Percent of total 25.3 :. }:: 31.4 216(. 7.6 35.7
^45.7 m x 3.0 m seine; other sites sanpled with 45.7 m x 1.5 m seine 2
Represents pooled total for 10 species of infrequent occurrence in haul seine Shaded colunn is data from surveillance station. Atlantic silverside The Atlantic silverside dominated seine catches again as it has every year since the j implementation of seining in 1981, accounting for 72% of the fish caught. Of the totaf ' silverside catch,48% came from Long Point and 34% from Warren Cove. Silversides did not ! appear in the catch in any numbers until August at all sites, when both juveniles and adults were captured. This species dominated catch-per-unit-effort (catch per set) at all stations except Pilgrim Intake, ranking second there. In percent frequency of occurrence of total catches,it ranked first at Warren Cove and Manomet Point, and second to winter flourhr at the other two sites. Catch rates for Atlantic silverside were down from 1987 except at Warren , Cove, with the greatest decrease at Long Point (down 73%), suggesting a decline in the local population.
. {
Sand lance sno. Ranking second, sand lance spp. were caught almost exclusively ( > 99%) in the Intake embayment at Pilgrim Station within the months of June through August. Sand lance spend a substantial proportion of their time burrowed in sand bottoms and may undertake seasonal migrations to deeper waters of Cape Cod Bay in winter (Bigelow and Schroeder 1953). The mean catch rate of sand lance at the Intake increased 10% from 1987. Blueback herrine Juvenile blueback herring comprised only 4% of the total and were captured primarily in the Intake followed by Manomet Point. Although ranking third in numerical abundance,it was fif th in frequency of occurrence.This species' schooling behavior affects its availability .l to capture by haul seine in any given year. Winter flounder and Atlan11g menhaden Winter flounder and Atlantic menhaden (all juveniles) ranked fourth and fif th, respectively,in catch. Winter flounder displaced Atlantic silverside this year for the top rank in frequency of occurrence, reflecting its relatively ubiquitous distribution. Catch rate for this i flatfish was again far highest at Pilgrim Intake (13.6), an increase of 50% from 1987. Winter flounder occurred in 92% of the sets made in the Intake in 1988. Menhaden was likewise most . l abundant in the Intake. 1 Seasonality and Diversity Seine catches (all species pooled) were highest in August and September, concomitant ! with the highest water temperatures of the year. This relationship occurs every year. By November, moderate catches were made at the Intake, Manomet Point and Long Point stations; silverside, winter flounder and blueback herring still inhabited the cooler shallow waters in late fall. I l Annual species diversity was highest at Long Point (17 species) and Pilgrim Intake (16 species). In terms of percent frequency of occurrence of dominant species, Pilgrim Intake was most like Long Point. Of the 21 species seined,5 were taken at all stations while 5 were taken at only one of the four sites. By contrast, of 29 species seined in 1987,12 were seined only at one station.
In summation, Pilgrim Intake was most similar to Long Point in total catch and finfish diversity. Both stations share two characteristics which may account for these similarities: they provide habitats which offer protection from heavy surf, and possess some degree of cover,lacluding vegetation which provides suitable habitat for small fishes.This contrasts with the exposed coastal stations, Warren Cove and Manomet Point, which have sand substrate with little cover and are periodically subject to heavy surf; species diversity was lower there. The I:nportance of vegetation in shore-zone areas that serve as nursery grounds for fish was reported by Reid (1954), who found the least populated areas were those whose substrate was composed of just sand, where protection was lacking and food not abundant. However, unlike preceding years, the total catch at Warren Cove approached that of the Intake and Long Point sites, due primarily to the larger than usual catches of Atlantic silverside at this site in September and October. Briggs and O'Connor (1971) found the Atlantic silverside preferred sand-filled bottoms, although large numbers were also taken in some vegetated areas. Additional Small Foot-seine Samoline Using a smaller foot-seine (6 m) also at low tide, a total of 3,326 fish representing 16 species was sampled in the shore-zone June through November (Table 6). The mean catch per standard seine haul of 28.2 for all stations and species pooled declined 29% from 1987. With a small salinity variation (range 28-35% ) amongst stations, temperature (range 8 - 23 C) is a more important factor influencing the seasonal occurrence and abundance of fish along the shoreline. Overall catch of the 6m seine was highest at Long Point followed by the Intake at Pilgrim Station. Species diversity was highest at the Intake, followed just behind by Long Point. Two taxa - Atlantic silverside and winter flounder - comprised over 97% of the catch. The silverside was reported as the dominant species in the shore zone of Long Island Sound at Millstone Point, Connecticut (Birely 1984).The Atlantic silverside was by far the dominant fish in numerical abundance caught in the shore zone of the Pilgrim area; over 94% of the fish captured with the foot-seine were silversides. Collected at all setning stations, this species comprised 85% or more of the catch at each site. Catch per standard seine haul (Index of relative abundance) was highest at Long Point at 53 per/ haul, followed by the Intake at 32 and
J l 1 then Long Beach at 27. : Relative abundance was similar at Warren Cove and Manomet Point ; at 12.2 and 7.5 per standard haul, respectively. 1 Table 6. Shore-zone fishes captured by foot seine at five stations I in the environs of Pilgrim Nuclear Power Statf or, Jure-Novenber,1988. Station 1 2 3 4 5 Long Warren PilDrip Manamet Long Total Percent of j Species Beach Cove intake Point Point Ntaber Total catch l l Atlantic silverside 642 294 [Y70ll 166 1262 3134 94.2 Winter flomder 4 16 1539$ 25 30 114 3.4 cener 0 0 ' !!!25li 0 0 25 0.8 Windowpane 5 4 lol 3 6 18 0.5 Northern pipefish 2 2 141 0 1 9 0.3 Orubby 0 0 15[ 0 3 8 0.2 LuupfIsh 0 0 .55 ? O 2 7 0.2 Other species I O 2 T4h 2 3 11 0.3 Total rumber of fish 653 318 [852? 196 1307 3326 Total rumber of sets 24 24 b 241 . 22 24 118 Catch per set 27.2 13.2 1 35.5 ? 8.9 54.5 28.2 Number of species 4 6 [ 10 t 5 9 16 Percent of total catch 19.6 9.6 125.6 i 5.9 39.3 I Represents pooled totals for nine species of low catch abundance, including little skate, blueback herring, alewife, white hake, Atletitic tomcod, rock gunnel, mtanichog, striped killifish, and shorthorn sculpin. j Shaded coluun is data from surveillance station. l Winter flounder were captured in greatest numbers in the Intal,e, followed by Long Point, which parallels the finding obtained with the larger seines. Overall, considering the much reduced area swept by the smaller foot-seine relative to the larger haul-seines and the actual number of flounder sampled by the respective nets, the foot-seine is proving to be an efficient i l sampler of juvenile flatfish. 1
- 4. Underwater finfish observations i
Observational diving began in early May, with a total of 13 dives made through mid-October. Nearly 900 fish, comprising 7 species (Table 7) were observed in the study area.
.w 1
Invertebrates noted included blue mussel (Mytilus edulls), lobster, starfish (Asterias spp.), and
, rock and Jonah crabs (Qgggr. borealis and Girroratus). Qualitative observation of Irish moss (Chondrus crisnus) growth and distribution in the discharge area continued as in 1987.
Table 7. Abundance and distribution of finfish species observed during underwater observations, May - october, 1988. Ntsuber station (s) Species observed % of where e st by divers total abundant Cunner 679 76.9 Dg Pollock 136 15.4 Cg Teutog 58 6.6 Dg + D2 other* 10 1.1 - Total 7 species 883
- Lunpfish, Rock gunnel, sea raven, Winter flounder Estimates of lateral visibility (obtained with a diver-held secchi disk and metered line) ranged from 3 - 10.5 m (averaging 6.3 m), depending on sea condition and incident light.
The number cf fish sighted in 1988 increased from 1987 (536 fish) but was far less in comparison to pre-1985 levels (2000+ fish). Sightings were fairly evenly distributed between
. the discharge (50%)-D1 and D2- and control areas (45%)-C1 and C2, with only 5% of the !
total observed in the stunted area - S1 and S2. Cunner Cunner was the species most of ten seen by project divers, comprising 77% of the fish recorded (Table 7). Found at all stations, cunner were most common in the discharge area at l Station D g. The total number observed was still far less than in the early '80's, reflecting a decline la local stock abundance as reported by Kelly et al. (1988). j Pollock <
- Observed primarily in the control zone (61% of all sightings), pollock ranked second (Table 7). The number sighted was 136 fish, which is a slight increase from 1987 (93 fish). However, it is worth restating, diver observation of highly mobile species, such as pollock, is problesnatical and does not necessarily equate to being representative of local abundance or distribution.
I Tautor Ranking third in fish sighted (Table 7), tautog were found nearly exclusively in the , discharge area. Although local abundance appears to be down, observations of tautog in the i discharge area have fluctuated widely since the inception of observational diving. j Other Snecies The remaining species comprised only 1% of the total sightings (Table 7); these fish were observed infrequently. l S. Soortfishine During the 1988 informal creel survey of sportfishing at Pilgrim Shorefront, conducted June-August, reportedly under 600 angler trips were made by shore fishermen to the area. Five l species of finfish were caught totaling less than 100 fish. Cunner (40%) and winter flounder (39%) comprised 79% of the total, while pollock, tautog, and striped bass accounted for the remainder of the recorded catch. Cunner has led the sportfish catch at the Shorefront since its opening in 1973. The relationship of this species to inshore structure makes this groundfish highly available to shore-based anglers, but at the same time places it in proximity to potential effects of inshore pollutants. I The opening of the Shorefront to the public was delayed from the 1st of April to the 20th. Quantitative catch data were first obtained on June 11, when BECo personnel were stationed at the Shorefront. Pilgrim Station has been in an extended outage sin:e early in 4 1986, which has negated waste heat removal and resulted in reduced discharge flow throughout l this period. Although no creel data were collected systematically in April, May or September-November, our observations in the area indicate that relatively few anglers fished there during these months, with catches being extremely low. At times the Shorefront area was closed to ) l the public. Fishing occurred principally from the outer intake breakwater and to a lesser extent from the two discharge jettles and the head of the intake embayment. Bottom fishing with I natural bait was by far the rnost popular angling method. I I I Fishing pressure increased over the spring, being highest in July, when over 50% of the fishing trips took place. Angling activity declined thereaf ter but was still relatively high in August. This pattern of fishing effort has been consistent over the years and le apparently influenced by favorable weather conditions and the traditional summer vacation period (Lawton et al.1987). Highest sportfish catches were recorded in July (82%) as was the case last year. Of the five species caught during the fishing season, each appeared in the July catch in greatest numbers. Cunner and winter flounder predominated with 70% and 92%, respcetitely, of their totals obtained that month. Only a few striped bass were taken; while bluefish were conspicuous by their absence in the recorded catch. Catches were markedly down overall from last year as was effort, with both parameters; reaching all time lows in 1988.
)
I i e t
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V. HIGHLIGHTS Lobster - Commercial Fisherv
- 1. Catch statistics and biological data for the commerr:lal lobster fishery in the Pilgrim area were collected from over 2,200 lobster taken from May through October 1988.
- 2. Catch per unit effort of total lobster essentially did not change from 1987.
- 3. Legal catch rate was slightly up, averaging 0.38 for 1988; the range was from 0.26 in October to 0.67 in August.
Lobster - Research Study
- 1. Fif ty sampilng days of research pot fishing (June-September 1988) yielded 6,456 lobster (52% male; 48% female) captured from 2,457 trap-hauls, with legals comprising 15% of the*
catch.
- 2. Catch rates (i.e., mean catch per trap-haul-CTH) of legals (t 81.8 mm carapace length-CL) and sublegals (< 81.8 mm CL) in the study area were somewhat higher than in 1987 but were substantially higher than in 1986.
- 3. Only 0.7% of the research catch of female lobster were ovigerous (carrying eggs) as
. compared to 2.1% of the commercial catch.
- 4. Carapace lengths of lobster la research catches ranged from 41-121 mm, and averaged 74.9 mm, which is 2 mm larger than means for the last 2 years.
Groundfish
- 1. Thirty-one fish species were collected by bottom trawling in the nearshore area of Pilgrim Station.
2.The average catch per standard tow for all species and stations combined decilned over 50% to 10.0 fish / tow. !
- 3. Winter flounder ranked first in total catch (51%) and was the numerical dominant at each j l
j station; total flounder catch declined 25% from last year.
- 5. Little skate again ranked second in total catch (18%), but its overall abundance declined -)
74% from last year. l 2s.
Pelanic and Benthl-nelante Fishes
- 1. Comprising 29 species, 3,620 finfish were netted during 13 overnight sets.
l
- 2. Annual mean CPUE of pooled species (241.9) was the highest recorded since 1977.
- 3. Atlantic herring ranked first, comprising nearly 50% of the catch. Pollock was second (33%) and cunner was third (6%).
Shore-rone Fish
- 1. Twenty-one fish species were captured in the 45.7 m haul seine study from June-Nooember 1988.
- 2. Declines in the catch rates of Atlantic silverside, blueback herring, and alewife greatly contributed to decrease the overall 1988 mean catch per seine haul for all species 7:ombined by over 50%; station catch rates for pooled species dropped at three of the four sites.
- 3. Atlantic silverside continued to dominate cat.:hes, comprising 72% of the total catch and ranking first in both overall CPUE and overall percent frequency of occurrenace.
- 4. Sand lance spp. were second in numerical abundance (18%) but low in frn.uency of occurrence; they were caught almost exclusively at the Intake station.
i'
- 5. Two species (Atlantic silverside and winter flounder) ccmprised 97% of tive (6 m) footseine catch with silverside far dominating.
- 6. Total number of fish, CPUE, and species diversity were highest at Lo9.g Point and the 1 Intake stations. 1 Underwater Finfish Observations
!. Nearly 900 fish, comprising 7 species were observed during 13 dives in 1988.
- 2. Total number of fish observed increased over 1987; 50 % were sighte:d in the denuded zone, 45% in the control rone, and 5% in the stunted zone.
- 3. Cunner was the most common species (77% of the total) and war found at all stations.
Sportfishine
- 1. An Informal creel survey of sportfishing was again conducted at the Pilgrim Shorefront recreational area but was attenuated (June-August) because r:.f financial constraints.
- 2. Reportedly under 600 angler trips were made by shore fisherraen to the area and less than 100 fish, representing 5 species, were caught.
Y
~ 3. Cunner (40%) and winter flounder (39%) led the catch with most anglers bottom fishing from off the outer breakwater.
- 4. Catches of all sportfish species were markedly down from last year, as was effort; both parameters' reached all time lows la 1988.
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VI. ACKNOWLEDGMENT We acknowledge the contributloss of numerous staff mesabers of the Division of Marine Fisheries (DMF), who assisted la varlons phases of data collection, compster programming, and data saa!ysis, especia% loseph Battaglia, Kevin Creighton, Theresa Ritchot, Virgiata Fay, and Karen Begley. W ; thr.ak Chris Kyranos, commerciallobsteranas, for allowing as to sample his lobsier catches, and Rayasond Dand nad Robert Ellenberger, Boston Edison (BECo) public relations' personnel, for gatherlag sportfish data at the Shorefront area. Also greatly appreciated is the work of Kim Trotto of DMF for word-processlag sections of this report. Finally, we thank Robert D. Anderson, BECo Semier Marine Fisheries Biologist, W. Leigh Bridges, Assistaat Director of Research for DMF, and the Pilgrim Adaalaistrative-Technical Comaalttee for their helpful suggestless and editorial comments while overseelag the entire study prograan. l i 1 l j VII. LITER ATURE CITED Aiken, D. E., and S. L. Waddy.1982. Cement gland development, ovary maturation, and reproductive cycles in the American lobster, Homarus americanus. Journal of Crustacean Biology 2 (3): 315-327. Bigelow, H. B., and W. C. Schroeder,1953. Fishes of the Gulf of Maine. U.S. Fish and Wildlife Service Fishery Bulletin 53:577 pp. Birely, L.E.1984. Multivariate analysis of species compostion of shore-mone fish assemblages found in Long Island Sound. Estuaries 7(3): 242-247. Boston Edison Company.1980. Benthic map overlays and assessment of beathic monitorlag programs, Vol. 2. Nuclear Engloeerlag Dept., Environmental Sciences Group. Boston Edison Company, Boston, MA, USA. 25 pp. Briggs, P. T., and J. S. O'Commor.1971. Comparison of shore-rone fishes over naturally vegetated and sand-filled bottoms in Great South Bay. New York Fish and Game Journal 18 (1): 15-41. Briggs, P. T., and F. M. Mushacke.1979. The American lobster in western Long Island Sound. New York Fish and Game Journal 26 (1): 59-86. Collings, W.S., C. Cooper-Sheehan, S.C. Hughes, and J.L. Buckley. 1983. The spatio-temporal distribution of American lobster, Homarus americanus. larvae in the Cape Cod Canal and approaches, p. 35-40. h M.J. Fogarty (ed.), Distribution
'and relative abundance of American lobster, Homarus americanus. larvae: New England investigations during 1974-79, 64 pp. NOAA Technical Report, NMFS SSRF-775.
( Conover, D.O., and M. R. Ross.1982. Patterns in seasonal abundance, growth, and biomass of the Altantic silverside, Menidia menidia. in a New England estuary. Estuaries 5 ! (4): 275-286. Davis, J.D.1984. Western Cape Cod Bay: hydrographic, geological, ecological, and meteorological backgrounds for environmental studies, p 1-18, h: J.D. Davis and ) D. Merriman (editors), Observations on the Ecology and Biology of Western Cape Cod Bay, Massachusetts. Springer-Verlag, j Berlin, FRG. 289 pp. Kelly, B. C., V. J. Malkoski, S.J. Correia, R.P. Lawton, M. Borgatti, and B. Hollister.1988. Annual report on j monitoring to assess impact of Pilgrim Nuclear Power Station J on marine fisheries resources No. 44. h: Marine Ecology Studies Related to Operation of Pilgrim Station. Semi-Annual Report No. 31. Boston Edison Company, Braintree,MA. } _ __
I Lawton, R.P., E. Kouloheras, P. Brady, W. Sides, and M. Borgatti. , 1983. Distribution and abundance of larval American lobster, Homarus americanus. (Milne-Edwards), in the western inshore region of Cape Cod Bay, Massachusetts, E
- p. 47-52. In: M.J. Fogarty (editor), Distribution and 5 relative abundance of American lobt,ter, Homarus gJnericanu,1, larvae: New England investigations during 1974-1979, 64 pp.
NOAA Technical Report, NMFS SSRF-775. Lawton, R. P., V. J. Malkoski, S. J. Correia, J. B. O'Gorman, and M. R. Borgatti.1986. Annual Report on monitoring to assess impact of Pilgrim Nuclear Power Station on marine fisheries resources of western Cape Cod Bay. Project Report No. 40 (Jan.-Dec.1985). In: Marine Ecology Studies Related to Operation of Pilgrim Station. Semi-Annual Report. 27. Boston Edison Company, Braintree, MA. Lawton, R.P., V. Malkoski, S. Correia, B. Kelly, C. Sheehan, M. Borgatti, and P. Brady.1987 Final report on Marine l Recreational Fishing at the Pilgrim Station Shorefront: 5 1973-1975, 1983-1986. Pilgrim Nuclear Power Station Marine Environmental Program Report Series No. 3. Boston Edison g Company. 53 pp. g Reid, G.K., Jr.1954. An ecological study of the Gulf of Mexico fishes le the vicinity of Cedar Key, Florida. Bull. Mar. Sci. Gulf and Caribbean 4 (1): 1-94. Robins, C.R., R.M. Bailey, C.E. Bond, J. R. Brooker, E. A. Lachner, R.M. Lea, and W.B. Scott,1980. A list of Common l and Scientific Names of Fishes from the United States and B Canada 4th Edition. Special Publication No.14. American Fisheries Society.174 pp. I I I 1 I I I I s 3
l I l i ! l ANNUAL REPORT i' ON I. MONITORING TO ASSESS IMPACT OF PILGRIM NUCLEAR POWER STATION ON MARINE FISHERIES RESOURCES I OF WESTERN CAPE COD HAY (IMPACT ON FISHERIES RESOURCES) ! Project Report No. 46 (January-December,1988) (Volume 2 of 2)
-I By I Robert P. Lawton, Brian C. Kelly, Vincent J. Malkoski and Mando Borgatti I
I I I April 1,1989 Massachusetts Department of Fisheries, I Wildlife, and Environmental Law Enforcement Division of Marine Fisheries 100 Cambridge Street Boston, Massachusetts 02202 I l I I
I TABLE OF CONTENTS Section ERIT. I. EXECUTIVE
SUMMARY
1 II. INTRODUCTION 2 III. RESULTS AND DISCUSSION 3 A. Physical (Ablotic) Factors 3 l
- 1. Power Output and Thermal Capacity 3
- 2. Discharge Current 3
- 3. - Water Temperature 4 I
B. Impact of Pilgrim Station on Fisheries Resources 4
- 1. Commercial Lobster Pot-Catch Fishery 4
- 2. Research Lobster Trap Fishing 10
- 3. Nearshore Benthic Finfish 13
- 4. Pelagic and Benthl-Pelagic Fishes 18
- 5. Fishes of the Shore Zone 22
- 6. Underwater Finfish Observations 25
- 7. Sportfishing 27 IV. IMPACT PERSPECTIVE 29 t
- V. CONCLUSIONS 32 VI. ACKNOWLEDGEMENTS 35 VII. LITERATURE CITED 36 I I I 1 i I 1 II
l I l I LIST OF TABLES Table P_ngg a
- 1. Catch per unit effort froma experimentallobstering in the Pilgrim 11 area for 1988. CTII represents catch per trap haul; CTIISOD Indicates catch per trap haul per set-over-day. Catch data area I presented in muunbers of lobster caugth. Memm i2 standard errcrs is an estirmate of precisloa.
I 2. Mens catch per standard gilleet set (5 panels of 3.8 - 8.9 cm 19 meesh) for various time periods and the percent differences for l selected species caught in the vicinity of Pilgrim Station, 1971-1988.
- 3. Mena catch per standard haul selse set for selected species 23 collected along the Plyanouth shorellae, western Cape Cod Bay, 1983-1988.
- 4. A suussmary of impact assessament by study of Pilgrim Nuclear 30 Power Stattom (PNPS) om nearine fisherles' resources la western Cape Cod Bay during the operational history of the power plant.
I I I I I I I I l I l I I g m
I LIST OF FIGURES Fleure P_Agt
- 1. Annual mean cumulative Pilgrim Station Unit I Capacity 5 Factor (MDC Net %) for 1972-1988 and circulating water pump operation at the plant for 1983-1988.
- 2. Surface water temperatures in the Sicinity of Pilgrim 6 l Station averaged by season area fer the years of high plant E5 operational status (1983 and 1985) and for one of the lowest (1988).
- 3. Lobster pot sampling grid for the commercial lobsterman 7 monitored in the Pilgrim Power Plant area surveillance (11-11,11-12, I-11, and I-12) and reference (E-13, E-14, g and F-13) quadrats are shaded] and distribution of his g traps sampled in 1988.
- 4. Annual legal lobster catch per trap-haul in control and 8 l Impact areas near Pilgrim Station, 1983-1988. 5
- 5. Mean annual catch per standard tow of dominant 14 groundfish by bottom trawl at reference Station 1 and surveillance Station 3, 1982-1988.
- 6. Seasonal mean trawl catch rates with vertical error bars 15 for winter flounder by station in the Pilgrim area,1988.
- 7. Seasonal mean trawl catch rates with vertical error bars 16 for little skate by station in the Pilgrim area,1988.
- 8. Seasonal mean trawl catch rates with vertical error bars 16 for windowpane by station in the Pilgrim area,1988.
- 9. Length frequency distributions by station for winter 17 flounder trawled in spring, summer, and fall 1988, near Pilgrim Station.
- 10. Average gill-net catch for Atlantic herring arid yearly 19 MDC Net % at Pilgrim Station, 1971-1988.
- 11. Average gill-net catch for pollock and yearly MDC Net % 20 at Pilgrim Station, 1971-1988.
- 12. Average gill-net catch for cunner and seasonal MDC Net % 21 at Pilgrim Station, 1971-1988. {
- 13. Distribution of finfish observed by divers off Pilgrim 25 Station, 1983-1988. l
)
- 14. Indices of relative abundance (fish /dite) for cunner observed 26 l by divers at Pilgrim Station, 1981-1988.
I ! i iv
I
- 15. Distribution of cunner observed by divers off Pilgrim 26 Station, 1983-1988.
27 I 16. Index of relative abundance (fish / dive) for tautog observed by divers at Pilgrim Station, 1981-1988. 27 l
- 17. Distribution of tautog observed by divers off Pilgrim Station, I 1983-1988.
I I I ' I I I I l I I , I 1 I I 1 l I . I I I " l
I LIST OF PLATES Plate 1. Biologist collecting length-frequency data from the catch of a commerciallobsterman in the proximity of Pilgrim Station. Lobsters constitute the area's most valuable fishery resource. Plate 2. Operations aboard a fishing vessel used during the 1988 experimental lobster study. l This investigation is designed to better assess the impact on lobsters of the thermal W effluent at Pilgrim Station. Plate 3. Retrieval of the experimental gill net af ter a standardized overnight set in the thermal plume area. Caught in the net is a smooth dogfish, a common summer migrant in the Pilgrim area. Plate 4. Fishes caught by gill-net in the area of the thermal plume at Pilgrim Station. l Gill-net catches include commercially important species, e.g., Atlantic cod, pollock, i Atlantic mackerel, striped bass, and winter flounder. Plate 5. Bottom trawl being set to sample groundfish in the inshore waters of western Cape Cod Bay. Catches are used to measure potential impacts of Pilgrim Station on the l bsnthic fish community. 3) Plate 6. Typical trawl catch is processed which includes identifying, enumerating, and gi measuring the different species for environmental assessment. Catches of winter flounder have been consistently larger at the Pilgrim Station intake trawl station. Plate 7. Haul setning in the intake embnyment at Pilgrim Station: the net is being set from a powered-skiff to enclose a rectangular area. Seine catches can be integrated with impingement data for a more comprehensive evaluation of potentialimpact on shorczone l fishes. E Plate 8. Haul seine catch processed on the beach near the Pilgrim Station intake (fish g are enumerated and measured). Among the shorczone fishes are important forage fish such as the Atlantic silverside and sand lance, and the juvenile stages of several g commercial species such as the winter flounder and Atlantic menhaden. Plate 9. Biologist-diver deploying a transect line between observational stations. Diving observations have recorded the greatest number of fishes in the " denuded" zone directly off the discharge canal. Plate 10. A tautog foraging at the mouth of the discharge canal (Station D) et Pilgrim Station. A popular catch of recreational fishermen, tautog are in the Pilgrim area from spring through autumn and have been used as an " indicator" organism to assess stress imposed by the release of the heated effluent. Plate 11. Pictured is the thermal effluent discharging into Cape Cod Bay and anglers fishing off the discharge jettles and from boats in the plume which is visible in the E f background by the calm water. Striped bass ana bluefish, which are attracted to and 5 concentrate in the thermal current, are the dominant species sought by sport fishermen at this location. Plate 12. Anglers seeking sportfish at the mouth of the discharge canal. Casting artificial lures is the most popular method of fishing ti:e discharge current which attracts a variety of species. I I e I
I
- 1. EXECUTIVE
SUMMARY
In accordance with the PILGRIM NUCLEAR POWER STATION NPDES PERMIT requirements of the U.S. Environmental Protection Agency and the Massachusetts Division of q Water Pollution Control, marine fisheries ecological monitoring and reporting were continued I in 1988. Marine Fisheries monitoring was recommended and approved by the Pilgrim Administrative-Technical Committee established to insure that Pilgrim Station has the benefit of quallfled scientific input and is responsive to regulatory agency concerns. Fisheries sampling data were collected from comparable reference and surveillance stations to assess plant operational impact. Emphasis was placed on comparing data from 1983 and 1985, years of high power plant thermat output (>80% capacity), with 1984 (outage),1986 (Iow output), 1987 and 1988 (outage). The extended power plant outage has underscored several findings. Sportfish catches of striped bass and bluefish were almost nonexistent without the thermal discharge current. Cunner are apparently attracted to the current at Pilgrim Station based on diving observations. There is evidence of an inverse relationship between the commercial legal lobster catch rate in the Pilgrim discharge area and the release of a cooling water discharge. I I I 1 I I I l _i_
I' 1 II. INTRODUCTION Monitoring studies have been conducted by the Massachusetts Division of Marine Fisheries to assess environmentalimpact induced by Pilgrim Nuclear Power Station. Ecological , investigations of fisheries resources in the surrounding waters of Western Cape Cod Bay for 1988 were funded by Boston Edison Company under Purchase Order No. 65216. Sampling data were collected from reference and surveillance stations throughout the year. Analyses included a summarization of the data and a discussion of findings in relation to the past. It is noted that the plant essentially did not operate the entire year of 1988. This outage negated the discharge of waste heat, while current flow was reduced. Measurements, enumerations, percentages, and indices of abundance are used in this report to identify trends and/or relationships in the data both spatially and temporally. Volume 2 is an assessment of power plant impact on the marine environment. We emphasized data comparisons from 1983 and 1985, years of high power plant therual output (> S0% capacity), with 1984 (outage year),1986 (Iow output year: 17.5% capacity),1987 and 1988 (outage years). Plates 1-12 (found on the next several pages) depict sampling data collection operations which were used to assess power plant impact on fisheries resources in the western lushore region of Cape Cod Bay. I I I' I I 2 g
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Catches of winter flounder have been consistently largest at the Pil-grim Station intake trawl station.
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1 III.- RESULTS AND DISCUSSION ] I A. PHYSICAL (ADIOTIC) FACTORS l l
- 1. Power outnut and thermal canacity j 4
'To assess impact of the thermal discharge at Pilgrim Station on marine fishelles' resources in the receiving waters of Cape Cod Bay, we have analyzed sampling data taking into account the Pilgrim Nuclear Power Station Unit I maximum capacity factor (MDC net %).
The latter is an index of the plant's operational output which approximates thermal loading (waste heat removal) to the marine environment. At 100% MDC there is a temperature rise la the coolant water of 15.1 C above ambient which is referred to as 4T. Since inception of power plant operation in July 1972, the annual MDC factor at Pilgrim Station has ranged from 0.0% in 1987 and 1988 (outage years) to a high of 84.4% in 1985 (Figure 1). The power level capacity was also extremely low (0.1%)In 1984 (essentially an outage year). Other high years when it exceeded 80%, besides 1985, were 1979 and 1983. In this report, we have stressed data comparisons for the pooled years of 1984,1986 (17.5% annual MDC),1987, and 1988 with the two recent years - 1983 and 1985 - of high operational output. Pilgrim Station has operated to date at a cumulative capacity factor of approximately 46%, which is expressed in the environment as a rise in water temperature of l Just under 7C al,ove ambient, or less than half its possible output. With this relatively low operational history, we likely have not realized the full extent of potential plant impact on marine life.
- 2. Discharge Current At Pilgrim Station localized currents are induced by the power plant's circulating seawater intake and discharge. The once-through circulating seawater system, besides removing waste heat from the plant's condenser tubes, releases a current of water which has the physical effect of scouring,i.e., creating an abrasive action on the benthic environment.
I Each of the two circulating seawater pumps draws in 586,739 liters / minute (155,000 gal / minute) of cooling water, discharging it back into Cape Cod Bay; a maximum discharge velocity of 2.1 m/sec (7 f t/sec) is obtained at low tide with both pumps operating. ; )
1 1 Temperature, salinity, and currents acting singularly or in concert are important determinants of occurrence, distribution, and abundance of marine life. During the pitat outage of 1984, one or both (late March to mid-August) circulating water pumps were off (Figure 1), this minimizing or at least substantially reducing the discharge current. In 1.986, both pumps were operated from January to early March; thereaf ter during the outage only one pump was operated. As the outage continued in 1987, the station's two circulating pumps were off frons approximately late February through early September, while one circulating pump was run during the majority of the other months. In 1988, one circulating pump was operated for much of January-March and June-December; from mid-April to early June, both pumps were essentially off. Two pumps were operated for most of 1983 and 1985.
- 3. Water Temneraturg In 1983 and 1985 (>80% power plant capacity), seasonal mean surface water temperatures were highest in the discharge area, as expected, because of the release of waste heat into the receiving waters of Cape Cod Bay (Figure 2). With the plant operating, the extent of the near-fleid area impacted by the discharge current has lucluded a 1,100 m8 - 1,400 m8' denuded' zone, primarily a result of scouring. A peripheral area of ' stunted' algal growth ;
of about 1,900 m8 to 2,900 m 8has resulted from the thermal component of the discharge (Bridges and Anderson 1984). When the plant has been at 100% operating load, we have measured a temperature differential (AT)in the summer of up to ISC between discharge and ambient waters. Temperatures in Pilgrim Station's thermal plume, with the plant fully operational, have peaked at 32C(surface and bottom). Conversely in 1984 (outage year),1986 (outage April-December), and 1987-1988 (outage years), water temperatures in the discharge area mirrored ambient levels (exemplar is 1988; Figure 2). l i B. IMPACT OF PILGRIM STATION ON FISIIERIES RESOURCES (
- 1. Commercial Lobster Pot-Catch Fisherv I Pooled lobster catch statistics from the surveillance (discharge) quadrats (11-11,11-12, I-11, and I-12) were compared with data from the reference quadrats (E-13, E-14, and F-13) 1 C_ _ ____ _ _ _ _ _ _
1 1 l Unit 1 Capacity Factor (%) I 100 1 90-80-70- j 60-50-El N
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) Figure 1. Annual mean cumulative Pilgrim Station Unit I Capacity Factor (MDC Net %) for 1972-1988, and circulating water pump operation at the plant for 1983-1988.
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located in Warren Cove (Figure 3) to assess the impact of Pilgrim Station on the locallobster population and fishery. Realistically, we can compare catch rates from 1984-88 data (1985 being the only on-line year) because the same lobsterman has supplied most,if not all, of the impact / control data (Figure 3); 1983 catch data is included in our discussion for an additional datnm point from an on-line year for the plant. Males slightly outnumbered females in the catch for the entire study area in 1988. Of all the lobster sampled,51% were males. In the surveillance area, males comprised 51% of the catch, while at reference quadrats, males comprised 53%. As in 1986 and 1987, the percentage of culls in the surveillance area in 1988 was markedly lower (14%) than in the reference area (44%). A chi-square test (Sokal and Rohlf 1969) showed this difference to be highly significant (P $ 0.01) in 1988, as it was in 1987. Lobster cull rate is enhanced by both lobster fishing and bottom trawl activity (Keser et al.1983; Estrella and McKiernan 1986). Both study locations are subject to an intensive commercial lobster fishery. However,in Warren Cove (reference area), commercial trawling is seasonally (November-March) conducted for groundfish; this may account for the higher cull rate there. The 1988 mean catch rate (catch in number of lobster per trap haul for legal lobster) la the surveillance area was 0.34 MEAN ANNUggGggSTER CPUE legals / trap-haul, while the reference area's u
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4 legal catch rate was lower at 0.25. Catch o.e - 1" - - rate at the control area increased 20% from "' ~ ' ' '
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during on-line/off-line plant status; online ) year catch rates (1983 and 1985) are figure 4. Annual legal lobster catch [ comparable with offline year rates of 1984 Per trap-haul in control and ; impact areas near Pilgrim and 1986 (Figure 4). Mean legal catch rates Station, 1983-1988. in the discharge (Impact) area have declined slightly over the last six years, ranging from 0.47 in 1983 to 0.34 in 1987 and 1988. This contrasts with the trend in commerciallobster landings for the Pilgrim area and for i coastal waters overall. With the cooler ambient temperature regime in 1984 (Estrella 1985), the early season molt apparently was depressed or at least delayed; this,in turn, would have affected recruitment to legal size and impeded lobster activity (Campbell 1983; Estrella 1985). The mean catch rate of legal lobster in western Cape Cod Bay was lower by about 50% or more in 1984 (0.32 legals / trap haul) compared to 1983 (0.61), 1985 (0.66), and 1986 (0.77). Catch rate for western Cape Cod Bay in 1987 declined to 0.51, but subsequently rose to 0.74 in 1988. Landings in our study's control area (Warren Cove) reflected this trend. According to Estrella (1985) and Estrella and McElernan (1986), the coastwide commercial catch rate (catch per trap haul) of marketable lobster in 1984 was lower than in 1983 and 1985 by 19% and 20%, respectively. Record lobster landings were documented along the entire Massachusetts coast in 1985 and 1986 (Estrella and McElernan 1986). Cape Cod Bay lobstermen had to contend with cooler spring temperatures again in 1987 which delayed the lobster molt, resulting in a 34% reduction in commercial catch rate from 1986. The upswing in the 1988 catch rate in Cape Cod Bay may well be the result of this year's normal spring bottom water tempera tures. Using several nonparametric statistical tests, which are not dependent on a given L distribution but usually work for a wide range of distributions (Sokal and Rohlf 1969), we have previously tested annual legallobster catch rates for the discharge and reference areas for block periods of time. The Kruskal-Wallis test had revealed no significant differences (P
> 0.05) between areas for the entire survey, for the preoperational/ outage years, or for the operational years. With the Wilcoxon's signed ranks test of legal catch rates for operational years arranged as paired observations (surveillance versus reference), we found no significant differences in CPUE (P > 0.05) between control and test areas (Lawton et al.1988).
I Catch sampling data and plant thermal output have been examined for a relationship using correlation analysis (Sokal and Rohlf 1969) of Unit I Pilgrim Station Capacity Factor (MDC Net %) versus mean legal catch rates for operational years for prescribed areas. j -e-
1 - 3 i Sublegals were not examined in this way because of the sampling bias of commercial pots. We . . i reported on finding a significant negative correlation (r = -0.57; P s 0.05) between legal lobster catch rate for thermal quadrats pooled (surveillance area) and mean annual Pilgrim Station .
. MDC Net % Capacity Factor for operational years (Lawton et al.1986).' We then ran a correlation analysis on the mean Unit I thermal output for the period of May-December, which -approximates: the lashore lobster fishing season, versus !egal catch rates for the surveillance area during operational years and also obtained a significant negative correlation coefficient. When two variables are correlated, cause and effect is not necessarily validated; < however, there is the sbggestion of an layerse relationship between the catch rate of legal-stred lobster in the impacted area (quadrats H-11, H-12, I-11, and I- 12) and the operating level "
of Pilgrim Station. As 1988 was an off-line year, no statistical testing of surveillance versus L control area catch rates were performed. As to the effect of current on catch rate, Auster (1985) reported that a water flow above
~ a critical velocity (46 cm/sec) will retard the foraging behavior of lobster by inhibiting .
mobility. It is reasonable to conclude there might be reduced trap catches in the immediate
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discharge area where current velocity may reach two meters /second. In fact, our diving observations have revealed few lobster in the immediate area of the discharge canal. However, i a direct cause and effect relationship between presence of the thermal discharge current and commerciallobster catch is difficult to measure because we have no control of fishing effort ' . or the location of the traps. In 1988, with considerably more current (at ambient temperature) emanating from the discharge canal than in 1987, catch rate of legal lobster remained ) unchanged in the surveillance area. Commercial gear in the impact quadrats is often set far enough away from the discharge canal that discharge current is not a major factor affecting lobster distribution and catch at those sites.
- 2. Research Lobster Tran Fishine k
A research lobster pot-catch sampling program was completed for the third consecutive -i late spring-summer season (June-September 1988). Our objective was to ascertain,in addition to monitoring commercial catches, whether Pilgrim Station measurably impacts the local
h J W ni l lobster population and fishery. Catch rates, size frequencies, sex ratios, culls (lobster with I l missing'and/or regenerating claws), and origerous females (carrying eggs) were examined, i i
~ From 2,457 trap-hauls,6456 lobster were sampled. Catch per unit of effort (CPUE) of l q
sublegallobster (s 81.8 mm carapace length - CL), as measured by catch per trap haul (CTH), f averaged 2.24 overall(Table 1), up from last year's value of 2.08. CTH weighted by immersion time (time between pot-hauls) of the pots (CTHSOD), which was the most appropriate measure l of CPUE for legallobster (2:,81.8 mm CCL), averaged 0.17 in the study area in 1988. CTHSOD of legals in 1987 was 0.15. Catch rates were substantially up from last year at the Rocky Polut reference area but remained about the same in the Discharge area. Table 1. Catch per unit effort from experimental lobstering in the Pilgrim area for 1988. CTH represents catch per trap haul; CTHSOD indicates catch per trap haut per
. set over-day. Catch data are presented in rubers of lobster caught. Mean 12 standard errors is an estimate of precision.
Legal sized Lobster Sublegal Lobster Q 81.8 nun CL) (< 81.8 nun et) Mean 12 Mean 1 2 Area CTHSOD Standard Errors CTH Standard Errors Entire study Area 0.169 0.157-0.181 2.242 2.164-2.320 Discharge Area 0.132 0.116-0.147 1.873 1.764-1.982 (Surveillance) Entire Reference Area 0.194 0,177-0.211 2.497 2.392 2.602 Rocky Point (Control) 0.228 0.205 0.251 2.609 .2.476 2.741 Priscilla Beach (Control) 0.131 0.108-0.154 2.282 2.111 2.453 (White Horse Beach) The overall sex ratio of males to females in the total catch for the study area was 1.1: 1 in both 1987 and 1988 and approximately 1: 1 in 1986. Within the respective surveillance and reference zones, males slightly outnumbered females la catch all three years of this study, except in 1986 at Priscilla/ White Horse Beach (reference) when more females were caught. The percentage of females captured that were bearing eggs (ovigerous) was 0.7% this year,0.8% in 1987, and 2.9% in 1986. No pattern has yet emerged within the sampling zones. In 1986 over 80% of the ovigerous females were captured at Priscilla/ White Horse Beach; whereas,in 1987 and 1988,10% and 27%, respectively, were taken there. About 50% of the e J.
egg-bearing females were collected in the Discharge area in both 1987 and 1988. In previous work done in the 1970's, Lawton et al. (1984) found that the number of small (s 82 rim CL) origerous female lobster captured in lobster traps in the discharge area was larger than the number caught in reference locations, in 1986 and 1987, the percentage of culllobster captured was about 20% each year. In 1988, the cull rate rose to 23% Over the three years, the density of culls (CTII) has been lowest in the Discharge area and highest at Priscilla/ White IIorse Beach in 1986 and 1987 and at Rocky Point in 1988 The field research lobsier trap study conducted from June-September for the last three years has been la effect a modified trial experiment under somewhat control conditions (i.e., the plant outage resulted in no waste heat discharged but there was a current flow, albeit reduced to one pump operating in 1986 and 1988, while current flow was at a minimum during the study period in 1987). The data will be compared with that collected from future high operational years. The outage at the power plant was fortuitous, giving us the opportunity to refine the sampling design. The work became a uniformity trial where we fished standard traps in a standaralred manner in the study area. The proper pairing of a potentially impacted / surveillance site (random stations selected within) with non-impacted / reference sites was of prime importance for us to assume that lobster at these locations would respond in a l similar way to changes in abiotic variables. Identical stations are not a requisite and,le fact, j probably do not exist because of multifarious environmental factors and their differential effects on habitats of varying characteristics (Thomas and Van-Voris 1986). We had selected i station pairs that we believed were likely to respond in similar ways to most .nticipated environmental changes. Two parameters offer promise for assessing lobster population Imptet at Pilgrim Station: catch rate (relative abundance) and size composition of lobster from trap catches. Using the sample mean with estimates of precision (Table 1) and the approximate test of the { equality of means of two samples whose variances are unequal (F-max test)(Sokal and Rohlf 1 1969), catch rates of legals (CTIISOD) and sublegals (CTII) were tested by pairing up sampling areas (Discharge, Rocky Point, and Priscilla/ White llorse Beach). Because no area pair
/
l _ _ _ _
i'
;u emerged as consistently being statistically alike in catch rate of legals or'sublegals af ter the .
accumulation of three sampling seasons of trapping data, we hate opted for the following . analytical al.proach suggested by Thomas and Van-Voris (1986). f4 Limited. to a slagle impact (t estment) site and- having established two reference (control) sites, we used the extended outage period (almost three years) at the power. plant as.a baseline (prestress) period io establish the relationship by using a ratio of the blotic. i measure (catch rate)la the impact site to that at the control sites (average of the two). The grand mean for CTHSOD of legals was 0.826 and for CTH of sublegs!s was 0.819. These values will be tested against operational data yet to be collected in this study.
-The Kolmogorov-Smirnov procedure (Sokal and Rohlf 1969) was used- to test slae distribution of lobster caught in the different areas. It was found that size frequency data of legals at both reference areas could be pooled to' increase sample size and then tested against slae distribution of legals la the Discharge for power plant impact.
- 3. ' Nearshore Benthic Flufish In 1988, Pilgrim Station discharged essentially no waste heat, but one circulating seawater pump was operational for varying periods each month (minimal in April and May) to produce a mescurable current emanating from the discharge canal. For comparative purposes,. trawl
. data from the outage years - 1984 and 1986 through 1988 - were compared with those recent
(. years when the plant operated at greater than 80% of its capacity (1983 and 1985). During i the low /off operational years, the amount of current coming from the discharge canal varied, depending on the number of circulating seawater pumps in use. Station 1 (Warren Cove) was considered the primary reference site and was compared with the discharge surveillance site, Station 3, for impact analysis of the thermal discharge. Mean annual catch rates for the three dominant groundfish - winter flounder,little skate, and windowpane - were exasuined for differences between reference and surveillance
- l. sites (Figure 5). If differences b rciative abnnlance of these dominant nundfish (ladexed by CPUE) resulted frons plant operation, one would expect to see
WINTER FLOUPOER LITTLE SKATE WPOOWPANE
= u e
"' 7
- n.
7 ?
/ 7 /
n-
"' / / 7 .- /
[ ,
; !!L
- l,sh[fB ,
? :
y,
; [?
?
y,
? ! 6/ " " """""
lan v
,ca m l Figure 5. Mean annual catch per standard tow of dominant groundfish by bottom trawl at reference Station i and surveillance Station 3, 1982-1988.
differences in 1986 - 1988 data at Stations 1 and 3 relative to 1983 and 1985, with the outage j year 1984 sandwiched in between.This was not apparent, as species annual abundance Indices for these two stations in 1986 - 1988 were independent of each other (no consistent trends). We have used annual mean trawl CPUE of selected finfish species to measure changes in relative abundance over time. Within annual catch rates for each species are ; marked seasonal patterns of abundance. The variance of a species seasonal mean is less than that of the corresponding annual mean catch rate; hence, seasonal CPUE's are more ! precise statistics to analyze trawl data. To investigate seasonal variation in trawl catch rates for 1988 at each station, we partitioned catch data for winter flounder, little skate, and windowpane by season: l winter (January-March), spring (April-June), summer (July-September), and fall (Or.tober-December). Choice of seasonal demarcations was based on bottom trawl catch rates ( at.d sea water temperature data collected at snapling stations in the Pilgrim area over the i last decade (Lawtor et al.1983). Comparisons between stations within a reason of tne l l { E
i WINTER SPRING HUMBER OF FISH / TOW NUMBER OF FISH / TOW 0.3 12 10 2.6 , 3 . 1.6 _ 1 06
~-
2
)
0 0 m b c!$Not a 'a$nSh YrYE n!7s Neh t ARGE R l'A ME STATION STATION SUMMER Fall. NUMBER OF FISH / TOW NUMBER OF FISH / TOW
'* * " ' ~ "
id 00
~
86 10 to -- 16 e a.::- Ic ,
~~
6
-*-~f Y y a 0 O swoon i swion a swim a swimo swooni svtion a swion 4 sweou e STATION STATION Figure 6. Seasonal mean trawl catch rates with vertical error bars for winter flounder by station in Pilgrim area, 1988.
overlap in the CPUE standard error bars gives an approximation of any significant l differences (at the 0.05 probability level) la catch rates. Trawl data Inherently are highly ! varichle, hence the large standard error bars for means la catch data (Figures 6-8). Winter CPUE's for the species selected were extremely low and will not be considered further. In spring, the relative abundance of winter flounder (Figure 6) at Station 6 (Pilgrim Intake) was significantly less than at reference Station 4 (Priscilla Beach) and primary reference Station 1 (Warren Cove). Conversels,in summer, winter flounder were significantly more abuadsnt la the Intake thsr at any of the other sampling sites.The difference between spring and summer indicates a shift to distribution of winter flounder. These is no indica-tion t'nal the relative shundance of windnwrane or little skate differed significantly among any of the stations during the sessons of 1988. ) .
WINTER SPRING
,,.aamen a eie no. , oma on F eWvoa a7 ao is as sa,_ so -
_u ... as __ an e at y
.: = = == m- E= = == =,-
$TATION STATION SUMIER FALL
#AAdeER OF FfeW70* DAActER OT FieWTOW 9 -
s ne t ._ at me t .; __
-- at S ede seN 'mYa* n!*e7en$e a!N
- Es
$TATION STATION Figure 7. Seasonal mean trawl catch rates with vertical error bars for little skate by station in Pilgrin area, 1988.
WNTER SPRING
, NUuuf A 0F Flew 70W ,NUteER OF FewTCw e
as a 60 g __
~~
g, a __ i t ht i 1 EEEEr $= nIIEEEE 'EEr' EIt'Ela E= EIeY=$a *IEs'
$TATION $7ATICN SUMMER FALL wuween or rewton
, muusta CF Fiawrfow as oo 1 ne -'
a4 (4 ap . .T' ' . . . . . , , , .
= a= := =. = a= = =..
8';ATION STATIGN l . _ f Figure 8. Seasonal mean trawl catch rates with vertical error bars j for windowpane by station in Pilgrim area, 1988. I f
SPRING 1988 FREQUENCV 12-a 4 10- ??, l f 8- ,
. m 0- ,$ l 0 l'
4- V; i ( o 0
' ?
u d l
]- l.
$ S p p p 6' ,, l i Og k . . i-
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W ~~' l O 14 20 24 27 30 33 36 30 44 TOTAL LENGTH (CM) SUMMER 1988 FAEQUENCY 10- f f., s 8- ty_mt l __ 0* o 3 F$ h4 !
' d' pf __p_
o k i > a- o t - - c 2-
/[ ,,,.
n n? g y , C Cr ' b J 0 Y' . . . .'1"i 3 13 16 22 20 29 32 35 TOTAL LENGTH (CM) l FALL 1988 FREQUENCY 10- .n n
/ 4 j
re ; o A' 6- : , 0
< l 4- _ l , ,
, i -
I # h)hh 1 yh la
.eb, '"
e, ,,
.z z
,WI,,
z 5 8 11 13 23 27 30 33 30 39 TOTAL LENGTH (CM) l 151 stATCHC3l $fAfl0N 3 C3 STA?t0N 4 UEI GTATION 3 l Fegun 9. Length frequency distributions by station for winternear / flounder trawled in spring, summer, and fall 1988, Pilgrim Station.
kr, Previous ' analyses of trawl data Indicated the Intake to be a haven for small
-winter flounder <22 cm total length, presumably due' to the algal cover, structure, and sheltered environment it provides (Lawton et al. 1985, 1986; Kelly et al.1988). To statistic-
. ally test this seasonally, we subjected this year's spring, summer and fall data for winter flounder to the nonparametric Kolmogorov-Smirnov statistical test for differences in
- length-frequency distributions between the Intake and the other sites. In spring, none of the compared length frequency distributions (Figure 9) were significantly different (p>0.05). In summer, winter flounder size distributions differed significantly (p50.01) between Warren Cove
- (Station 1) and the Intake (Station 6). An examination of these length frequencies (Figure 9) reveals this difference is due to the greater abundance of larger flounder at the former -
locatloa. In fall, there was a highly significant difference (ps0.01)in the size distribution of winter flounder between the Intake and each of the other three sampling locations. Figure 9 also reveals an autumn pulse of small flounder (5-12 cm totallength) residing in the Intake;
' these fish are subject to impingement and/or thermal backwash effects from Pilgrim Station.
la fact, winter flounder (5-12 cm total length) was tied for third in impinged fish in 1988 at { the plant. I
- 4. Pelanic and benthl-nelmale fishes I A gill met is a passive sampling device; hence our survey abundance index (fish / overnight gill net set) was influenced by species availability and gear selectivity. We accepted the assumptions that gear efficiency did not change over time and sishing effort q i
of the net was uniform for all mesh sizes. We assumed that the number of fish already caught did not influence the capture of additional fish and that the vulnerability of each species was constant. Atlantic herrine Atlantic herring comprised 48% of the 1988 gill-cet catch. Over the survey years, D { p abundance in the Pilgrim area has fluctuated greatly. Following an initial decline in 1972, j CPUE senerally increased during the operational years of 1973 to 1976, declining again in 7
. 1977 and 1978. From 197'r to 1984, catch varied, but declined to an all-time low in 1985.
Beginning in 1986, relative abundance lacreated; the annual catch rate of 116.5 fish / set in j (
i i 1988 was the highest recorded f or this species. A plot of annual Pilgrim Station operational i output (MDC) and annual catch data is found in Figure 10. When tested statistically, sea i herring catch rate and plant MDC were not significantly correlated (r =-0.221; P >0.05). Comparison of CPUE between years of operation and reoperation / outage were Inconclusive (Table 2). The grand mean ! l catch rate for the operational study years j Atlantic Herring (1973-1983,1985) was much higher (312.8%) u n c. ion n., own.r ... uocw.i woiu ns than the average for the preoperational ,,,, eo period (1971-1972), while catch rate was '*- eo 378.7% higher for the average of 1984/1986- .,, 1988 (outage or low plant output) than the .,o average for 1983 and 1985 (> 80% plant o. .. . . . . . . . . .o 71 72 73 74 75 70 77 78 10'80'81'82'83'84'86'80'87'88 veer capacity). We therefore conclude that
- u..n cPUE EE MDc N.t 1 fluctuations in sea herring abundance in the Pilgrim area are the result of natural Figure 10. Average gill-net catch for Atlantic herring and yearly MDC variation. Net % at Pilgrim Station, 1971-1988.
Table 2. Mean catch per standard gittnet set (5 panels of 3.8 8.9 cm mesh) for various time periods and the percent differences for selected species caught in the vicinity of Pilgrim Station, 1971-1980. Species Atlantic Year Pollock Cunner herrina _ 1971 1972 93.8 18.8 7.8 1973-1983. 1985 81.3 32.9 32.2 Preoperational - operational -13.3 75.0 312.8 percent difference 1983 and 1985 62.4 25.9 9.1 (> 80% capacity) 1984, 1986-1988 56.6 18.5 A3.6
,{g21poe veers) 1983/1985-(1954/1986- -9.3 -28.5 378.7 y
1988) peggent difference
~
) -
P.D.I19.gk This benthl-pelagic species ranked second, comprising 32.7% of the 1988 gill-net catch. Relative abundance estimates, generated from CPUE data, reflect local population fluctuations over the survey years (Figure 11). An increase in relative abundance occurred from 1971-1972 (preoperational years), followed by a substantial reduction from 1974-1976. Stock index rebounded in 1977 to exceed past levels and remained relatively high through 1981; CPUE declined markedly in 1982 and subsequently fluctuated at a reduced level, declining overall through 1987. Catch rate in 1988 (91 fish / set) was a marked increase over the 1987 level (40 fish / set). Comparing means'of CPUE for k the preoperational (1971-1972) and Pollock operational (1973-1983,1985) study years; Mean Colch per Oni-Net set MDC Not Annual Mean % and between 1983/1985 when Pilgrim "o - _ Station operational output exceeded 80% and o; 1984/1986-1988 (outage periods), revealed, Go-
\ N,) -
f~ 3
~ h '
'40 respectively, that relative abundance was j 20 I 71 h,,y , , ,,,,,,,,, ,,
13% lower overall during the operational , 72 73 74 76 78 77 78 79*80'81 12 93'84'85 16 17 18 years and 9% lower in 1984/1986-1988 Year
~ " * * " " " " ' ' '
pooled than in 1983/1935 (Table 2). Comparison of the annual ladex for Figure 11. Average gill-net catch for I d pollock and yearly MDC Net % at Pilgrim . Station operational output and Pilgrim Station, 1971-1988. I CPUE data for pollock revealed no apparent l relationship (Figure 11); when statistically tested, we found no significant correlation (r =
\
I 0.198; P> 0.05). Cunner Cunner ranked third in gill-met catch (6%). There is evidence of population consistency . in the Pilgrim area from 1971-1976,(Figure 12) with a grand mean CPUF for these years of j 22 fish per gill-net set. Catch rate peaked in the operational years of 1978 and 1980. From 1977-1983 annual catch rates were about double (grand mean CPUE of 41 cunner per set) that { i obtained the first six years of the survey, Indicating a marked change in distribution and/or 1
^
abundance of the local' population. Relative abundance exhibited a marked decline for-1984-1988, averaglug 18 fish per set. _- cunner Pooled CPUE for. cunner captured so *""'""'****'I8"""*'"""*'"""*"*"T during operational years ,was 75% Sigher 40-p\ % so than the average for the two pre-operstlanal 8' _ eo
~
years (Table 2). Similarly, a 28% increase ' ' # - Ly
* ~
was noted for 1983/1985 ' (high thermal q output) over 1984/1986-1988 (outage / low. 4' 42 da i4 de is fr ia do so ei s2 es s4 ee is dr es -j YO8r output years).' A plot of seasonal (spring and -uun ceue CJuocu.is
- summer, when cuaner are present in the Figure 12. Average gill-net catch for area) plant . output versus cuaner CPUE cunner and. seasonal MDC Net % at Pilgrim Station, 1971-1988.
suggests there is a relationship between the two variables (Figure 12). When we tested CPUE data and seasonal plant MDC, we found a significant positive correlation (r =0.620; P
< 0.05). Regression analysis of catch rate on seasonal plant capacity factor yleided a highly significant F ratio (Fs = 9.38; P s 0.01). Specifically,-38.5% of the variability in cunner CPUE l' can be' explained by variation in plant operational load (MDC).
Supporting . evidence for a positive relationship between cunner abundance in the Pilgrim Station discharge ' area and plant thermal outflow / current comes from our ) observational diving program. _ During operational years, when the plant produced a warm dinharge current, divers sighted more cunner la the discharge zone than in the reference l areas. Even if no waste heat was released, the generation of current by at least one circulating _ seawater pump was sufficient to produce a similar distributional pattern. Conversely, dur'ag years when little or no current was released, cunner were more often observed at reference l stations. In conclusion, cunner are attracted to the cooling water discharge at Pilgrim Station. In the near-shore marine environment, active cunner occupy small home ranges for long periods l making this species appropriate for monitor!ng lorig- and short-term changes in local environmental conditions (Green 1975). As such, they are at risk from potential nearfield plant ) .
. impact such as from thermal or cold shock and exposure to chlorine. Cunner are especially vulnerable at night la that the low level of responsiveness which is characteristic of the sleep state of labrid fish reduces the potential to avoid environmental stress that may occur nocturnally (Olla et al.1975).
5.. Fishes of the shore zone Fishes that occur along the local beaches are subject to impact by. Pilgrim Station. Waste heat, gas supersaturation, scouring, and the mechanical effects of Impingement and entralament can adversely affect fish. The shore-zone seine program has allowed us to catalog finfish species (Juveniles and adults), including their occurrence, distribution, size range, and relative abundance in the latertidal and shallow subtidal zones of the Pilgrim area. The rocky shoreline, jetties, and outer breakwater in the area of the discharge precludes seining; however a suitable survelliance selaing site (to address mechanical effects) occurs at the head of the Intake embayment (Station 3) at Pilgrim Station. Reference statiour include two locations on open coastal beaches and a site at the mouth of the nearby estuary. l Relative abundance data (i.e., mean catch per standard seine haul) of the dominant species were examined to assess plant impact (Table 3). There are large natural variations in relative abundance amongst stations and years for many species with the exception of winter i flounder. Natural variability confounds the quantitative detection of other than large ; i i
- ecosystem level effects (mechanical or from waste heat discharge) of power generation. Using correlation analysis, we tested the relationships between monthly mean densities of the !
l Atlantic silverside, the study area's dominant species,in the Intake at Pilgrim Station and the monthly mean Pilgrim Station thermal capacity (MDC net %); and between the former and the monthly average plant pump capacity. No statistically significant correlations have been found (P > 0.05). Haul seine collections from the Intake embayment identify finfish species subject to { impingement. Of the 17 fish species seined in the Intake during the 1988 survey (June- ( November),13 were impinged on the power plant's latake screens during the same time period. y With the station outage and resultant decrease in pumping capacity, impingement for this
l Table 3. Mean catch per standard haut seine set for selected species collected along
. - the Plymouth shoreline, western Cape Cod Bay, 1983-1988.
Stations Warren Cove Lons Pt. PNPS Intake Menomet Pt. P91ed 2 Year Mean Catch Per Haut Siine set Attentic silverside 1983 103.7 197.7 s:10.0 L .119.1 1984 51.2 220.9 i41.43 101.7 1985 413.5 165.4 i(12.ti 201.5~ 1986 21.5 107.0- . f2.9) 46.9-1987 123.9 837.9 sly!l70.8} 58.5* 287.4** 1988' 174.7 224.2 - 90.61 45.3 121.7 " Mean 148.1 292.2 I;M8)! 51.9 146.4 Winter fleander 1983 1.0 4.9 s 4i-0.5.;i 2.4 1984 .1.1 2.9 ij!!2.0;@ 1.8-1985 1.0 7.4 s (l4.8;{ 4.5 1986 0.4 - 4.3 i.;rt.3 @ 4.3 1987 0.6 1.1 Ji:9.0) 2.8* 3.3** 1988 1.5 2.2 ill13.4 ji 2.0 5. 0" Mean 0.9 3.8 !!$1il 2.4 3.6 st. h ir herrino 1983 1.0 13.1 s o.O si 5.6 1984 0.1 0.2 ...:10311!! 1.1 }' 1985 352.0 4.9 !!;18GTj!!! 178.2 1986 1.8 14.3 i95.9 c:; 32.9 1987 1.2 - 0.1 j1125.8[! 0.4* 31.1** 1988 0.1 0.0 ' (22.4jii 4.9 7.1" l Mean 59.4 5.4 S72j1} 2.7 42.7 send tance soo. 1983 0.4 0.0 30.6 jij- 0.3 f- 0.5 0.2 10.7 i 1984 .X40.61 1985 0.0 0.0 ![449.$li 140.5 1986 0.0 2.0 yt72.3j!{ 21.2 ! 1987 0.1 0.0 jf"2.Sjii 0.2* 25.2** 1988 0.0 0.1 pij13;4j!! 0.0 29.5 "
........e....
Meen 0.2 0.4 ,@j29;9.],ij 0.1 37.9
- Ponted species 1983 188.1 253.7 134J.j!; 176.8 1984 54.3 233.8 .192.9.{ 120.1 l 1985 854.5 186.9 [688.4jl 569.0 1- 1986 30.9 150.5 lll'225.9;!!l 129.0 F
1987 130.0 847.5 '[.380.4)!i 63.4 368.1 " 1988 177.0 230.7 l?t06(1jj!' 53.6 169.4 " Mean 239.1 317.2 '!(UA[N]if 58.5 255.4
*First full season of date collected at this site.
)
** Includes date from Menomet Point in the relculations.
- l. Shaded columri is date from surveillance station.
I j .
period was low - 23 species totaling only 86 fish of which Atlantic tomcod comprised one-ithird. Sand lance (56%) and Atlantic silverside (20%) numerically dominated seine catches in. the Intake. Numbers caught la the seine were highest in July and August; while
~ impingement numbers were greatest in November, the impingement rate peaked in March.
The Intake at Pilgrim Station is an artificially created embayment or cove formed by man-made breakwaters and includes a dredged channel. This area.ls a microcosm of a naturally formed bay or inlet of the sea and has proven to be a haven for shore-zone fish in an otherwise open coastal region. The Intake offers a variety of fish habitats: shallows and a relatively deep channel; sand substrate devold of macroalgae and vegetated areas; and glacial boulders, cobble, and gravel. The area has reduced wave action because of protection afforded by the' outer breakwater which also provides shelter for marine life.' Unchecked waves of sufficient size can limit the distribution of blota as turbidity of the water increases and substrate shifts. Rocks and macroalgae both provide structure / cover for juvenile and forage fish and harbor the prey organisms on which these fish feed. Marine shore zones that are without aquatic vegetation or rocks generally are the least populated by fish because protection k is lacking and food is scarce.
- Relative to the number of species collected, total fish caught, and catch rate, the Intake <
1 ls most analogous to the estuarine sampling location on the inside of Long Beach, a barrier 1 beach that forms the outer bound of Plymouth Harbor, providing a sheltered haven from storm waves. By contrast, seine catches at the exposed coastal beaches were markedly lower in number of species and generall la total catch. However, fish concentrations in the Intake, especially la proximity to the lutake screen wall, are predisposed to mechanical effects of the power plant. Seine abundance indices (catch per standard haul) were examined over the last six years ( (two on-line years of high operational output - 1983 and 1985; four essentially outage j years - 1984,1986,1987, and 1988). No relationships between catch and plant operation are I suggested from the data (Table 3). However, some trends have emerged. Catches in 1986 and / 1987 were generally cc::nparable with the exception of the large increase in Atlantic silverside q in if 87. The latter species and blueback herring declined substantially in relative abundance in 1988, while winter flounder and sand lance spp. remained relatively stable. Catch rates of
.I blueback herring and winter flounder have been highest in the Intake for the last three years.
Sand lance catches have consistently been higher in the Intake. I To date, no correlations to plant operation have been detected from seine data. The construction of the intake embayment has nevertheless provided new habitat that did not exist at Rocky Point allowing for the development of a more diverse community there, with more niches to be filled. This finding was confirmed with foot seine data.
- 6. Underwater finfish observations With the continuation of the plant outage through 1988, no waste heat was released from Pilgrim Station. However, one circulating water pump was in operation during nearly an of the diving study. Project divers noted lower densities of blue mussels and ep L; itdc macroalgae than in the previous outage years.
In 1987, Lawton et al. (1988) noted an initial recoloulution of the denuded (dischange) area by Irish moss (Chondrus crisnust This trend continued during 1988 to the extent that project divers experienced great difficulty differentiating distinct boundaries between the denuded and stunted areas. Overall pooled finfish distribution (Figure 13) was similar to that for most of the previous years, with the majority of fish (50%) found la the discharge area. However, a higher percentage of fish were found in the control area in 1988 (45 %) than in either Pooled Finfish Distribution 1986 or 1987 (31% and 36%, respectively). p.,c.n w nnn,n
'~
Only 5% of the fish observed in 1988 eo-
~
occurred in the stunted zone; an index of 3.2 , fish / dive was the lowest recorded for this so- _ area during the entire survey. The total () _ number of fish sighted was 883, up from 536 I66 s66_{6 6._ 566 66 I in 1987. Species diversity (7 species) and o , 33 C 3 toee ga ,... C 3 iner o 3,33 C D ioes composition were similar during recent years. I No gamefish were sighted in 1988, however. Figure 13. Distribution of finfish observed by divers off Pilgrim Station, 1983-1988. I _
-2s-
Cunner Cunner was again the most frequently observed species at 778/o of the total. The number of cunner (679) for 1988 markedly increased from the low of 1987 (422), but remained far below past records. A plot of annual cunner per dive, as an index of relative abundance (Figure 14), revealed marked variation between survey years with a strong pulse in 1984 and the sharp decline of 1987. A comparison with project gill net records revealed there was a close agreement with the trend noted for cunner relative abundance in the discharge area. Cunner were found at all stations la 1988, with highest numbers in the discharge 2* area (Figure 15). A comparison rlth previous iso - years revealed similar spatial distributions ,o0 . for 1986 (outage), and 1983 and 1985 (operational years). Although no waste heat 1G01 1982 1983 1984 1985 1986 E1987 1980 was released in 1986 or 1988, at least one *= us tow Ar circulating water pump was in operation f throughout these years. Apparently, cunner Figure 14. Indices of relative ' abundance (fish / dive) for cunner are attracted to the discharge current, observed by diver at Pilgrim perhaps as a source of food. In support of this contention, a significant positive ; correlation (r= 0.620; P<0.05) was found
,,c.a.
between project gill-net CPUE and Pilgrim '" Station thermal output (MDC). *
; -_ f _- g Pollock *'
E- f 20-_ R - l ; Pollock was second in observed abundance, ' gj : J ! - r-> h belug sighted primarily in the control area. : o. ta ma c a ise. a me Sightings (136 fish) were up from 1987 (93) but ca me ca m7 cm me i estimating pollock abundance solely from visual Figure 15. Distribution of cunner I observed by divers off Pilgrim observations is tenuous because of their active Station, 1983-1988. behavior. Local abundance and distribution are more dependent on natural variability than any effect of the plant.
t Tauton I Tautog sightings (4.6 fish / dive)lucreased from 1987 (1 fish / dive), but remained f ar below 1985 and 1986 levels (Figure 16). Increased catch was noted in project gill-net collections. As has been the trend (Figure 17), tautog were found almost exclusively in the denuded area. To date, no definitive relationship has been confirmed between tautog and plant output (mean seasonal MDC). Fluctuations in local abundance are obviously influenced by recruitment (year-class strength). E I ,e - E E 70-
~
m Il M j .,, ,,, b; I I $ hi f . I_E to-
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Figure 16. Index of relative Figure 17. Distribution of
'I abundance (fish / dive) for tautog observed by divers at tautog observed by divers off Pilgrim Station, 1983- 1 l
Pilgrim Station, 1981-1988. 1988. f
- 7. Soortfishine J Angling activity (fishing effort) and resultant sportfish catches at the Pilgrim Station Shorefront recreational area declined further in 1988 from the previous lows of 1987.
Presumably, decreased fishing pressure resulted,in part, from publicity about the poor fishing ) j in the 1986 and 1987 seasons (Pilgrim Station was off-line). Poor catches were clearly linked to the extended station outage. In 1988, nngler trips declined over 50% from 1987, and sportfish catch was only a third of the preceding year. l Throughout the 1988 fishing season (April-November) at the Shorefront, Pilgrim Station released no waste heat into the recchlag waters of Cape Cod Bay. During April and May, both circuls> ting water pumps were essentially inoperative, and only a minimal flow of i l -n-
I water issued from the discharge canal. One of the two circulating pumps was operated much , of June-November, but, nevertheless, the volume of water discharged was reduced by half with only one pump operating. A lack of a strong thermal current at Pilgrim Station has negatively impacted recreational fishing at the Shorefront area (Lawton et al.1987). Outages have resulted in ' marked reductions of game fish catches,especially striped bass and bluefish. In 1983 and 1985
-(high plant operational years), an estimated 1,000 bluefish and 150+ striped bass and 2,200 bluefish and almost 400 bass, respectively, were landed at the Shorefront. Conversely, with the absence of a heated discharge current during the fishing seasons of 1984 and 1986-1988 (outage periods), the combined catches of bluefish and striped bass declined drastically to about 150 fish total for all 4 years.
As to prime feeding grounds, bass and bluefish have a propensity for moving water. Wooluer and Lyman (1983) noted that moving water is the choice of striped bass which prefer to lie in a current and,like other robust game fish,are prone to actively feed where the current is strong and rest where the flow is gentle. Lyman (1974) reported that bluefish,likewise, are attracted to moving water (e.g., tidal currents). Lund and Malteros (1970) observed that bluefish will come to the surface at dawn to feed and will continue feeding until tidal flow wanes or light latensity increases. On foggy or overcast days, bluefish of ten feed at or near the surface until the current slacks. When Pilgrim Station is operating,its thermal effluent g; I E i is a continuously flowing, artificially created current with a thermal component that has been l found to attract and concentrate feeding bass and bluefish. l i I I I. I 2e-Il
I I IV. IMPACT PERSPECTIVE A summary of the major findings of impact of Pilgrim Nuclear Power Station on fisherles resources la the Inshore sector of western Cape Cod Bay, focusing on the immediate area around the power plant,is presented by study in Table 4. The summary highlights sallent points; for more detailed discussions of Investigative area refer to the ledividual sections of this report. There are commercially important lobster and groundfish fisheries as well as Intensive recreational hook-and-line and lobster fisherles in Western Cape Cod Bay. The living and nonllving components of the environment govern many reactions of the species populations I comprising the marine community life. The assessment of environmental impact of Pilgrim Station on the area's fisherles' resources necessitates measuring many parameters that influence the occurrence, distribution, abundance, and size composition of target species. Monitoring data collected to date off the power plant reveal local blotic changes and environmental disruptions; however, these have been localized or occasional in occurrence. As Pilgrim Station has operated overall at an average of 46% of its output capacity, we most likely have not experienced plant impact to its fullest. Impact assessment at the past level of plant output may not be valid for a long-term, higher operationallevel that is expected in the future. I I I I I I I I.
-2e-
I Table 4 A summary of impact assessment by study of Pilgrim Nuclear 4 Power Station (PNFS) on marine fisheries' resources in western Cape Cod Bay during the operational history of the power plant. Investigation impact of PNFS 1983/1984/1985/1986/1987/1988 Connients Cill-net st'ady Cunner evidently attracted to Relative abundance of conner The implications of the thermal effluent, Significant in the sres of the thermal attraction are twofolds positive correlation to PNPS discharge down in 1984 to sport fishermen thia ) operationa.1 thermal loading. (outage year) and down is beneficial, but con-further in 1985 (high output versely this concentrates capacity), suggesting a fish in a high-risk area recent d,tcline in local with the potential for stock eiss. CPUE in 1986 was overfishing, thermal similar to that in 1985. In stress, gas bubble disease, 1987, CPUE declined iurther and exposure to chemicals. l Mit be w 1d back in 198P. There is a (t) relationship between Relative abundance of game as above. CPU for tautos and PNP 5 operational tautos wan not appreciably output, different over these years. SCU8A observations supporting dets that cunner are Increased conner sightings in With no thermal effluent (1984s attractee to the plant dischargn the control rene in 1984/19873 1987) there was an apparent
+ current in the discharge in 1981, shift in distribution of 1985 1986 and 1988 (reduced cunner away from the dio-current), charge (danuded) sone and toward the control some. l Concentrations of striped bass in the vicinity of FNPS linked to the cooling water discharge, On two occasions since 1979, As base exhibit a prefer-bluefish and base were not sighted by divers in the environe of FNPS- 1984/1988 ence for moving water, such as PNPS affluent, their absence from the lt l l
but were sisated in 1985 diving area in 1984 and 1988 is , in small schools frequenting apparently related to j the discharge area. Only a the low discharge flow few bass were siten in 1986-C7. during the outage. Creel survey With the plant operating, the Over 1,000 bluefish and > 150 Pcwer Plant has had a outf all at PNPS has proven to be an striped bass were caught by positive effect on the attractive feeding ground concen- anglers at PNPg in 19833 and sport fishing off Rocky trating sportfish for en extended 2,200 bluefish and almost 400 Point: however, the attrac-period of time in a location close bass in 1985g no base and only tion of game fish to the to ahore , a small number of bluefish discharge increases the were caught in 1934. Catches potential for overfishing were -extremely Icw 1986-1988 a local atock and for fish I during the plant outage. kille via high temperature and ges supersaturation. Bluefishing was prolonged into November 1985 by the presence of the hot-water discharge. - Raul-seine study Intake embayment with its break- Seine catches au the intake $haretone finfish residing water end dredged channel appears increased in 1984 and 1985. in the intake, especially in to be a haven for fishes in an but were down in !!'56, the vicinity of the intake otherwise open cometal region, back up in 1987, but down in screen well, are subject 1988. to plant entrapment, impingement and thermal backwash effects. Trew1 study Wintet flounder may avoid the A bimodal distribution of Autaan trende (plots) of immediate ares of the dia- flounder relative abundance relative abundance for winter charge canal. Catch abue- was feund at the surveillance flounder were differest dance of winter flounder,. yellow- station in 1984 that was nnt at reference versus survell-tail flounder, sad windewpane was found for 1981-1983 1985- lance sites from 1G -1983 1988. In1986-41,b70Einthe (operational years) but found to be correlated (positive) to PHPS K.D.C. factor (output) whee discherge area exceeded that were steller 1984/1986-19f.8 tta plant is operating. at the ref erence locetion. In (outage).In 1985, we f ound 1988. CPUE was alightly higher CPUC to be correlated (+) at at the reference station
- reference and discharge areas.
Concentrating in ene channel of catch-per-effort for winter Seasonal bottoa trswl catch the intake embeyment are flounder dropped markedly in ratta for winter flounder 1984 and 1985 at both the were consistently highest in winter flounder. reference and discharge the intake embayeeot in stations. CPUE arabilized the sunner and f all. In 198f and 1987, declining This is a boon to recrea-oosewhat in 1988. tional fishermen at PHPS shorefront.
- 3 0--
T bis 4 Trevi study (ctat.). Thj 11 tike et PNPS. en Eltirtd ' A compariscn of 1983 to 1984 This situitiss his ths environment has characteristics - is act applicable because potential for negative (relatively sheltered habitat with routine trevling was not con- impact,for it increasse rock and algal cover) which apper- ducted in the intake in 1983. susceptibility to l
,ently attract juvenile fish ,. However, comparing the ; impingement end thermal l
$acludingwinterflounder. catches in the intake with ! backwash effects. ]
the other sites sampled f rom 1984-1987 we found that sub-stantially larger numbers of smaller winter flounder w re in the intake channel in opring and/or summers in 1988-fall. Lobster pot-estch study There may be a connection between Catch rate of legal lobster A significant negative PHPS cooling water discharge and declined overall in the study correlation (F $ 0.05) legal lobster catch rate 'in the area in 1984 free the 1983 exists for annual
'dischstge area. level and was the lowest value thermal capacity and for the 15-year study: legal lobster catch rate increasing again in 1985 by - in the impacted eres about 100%. In 1986. CPUr. and a correlation (ness-was the highest of the entire tive) (F $ 0.10) between survey but dropped in 1987 to seasonal thermal capacity a level identical to 1964. An andcaIaa=Yiththeplant ch unswinz uccurrea in 1906. naarac .
Dissolted see snelysis In August 1985. FNPS wee operating No CBD incidents observed in Cao supersaturation and gas bubble disease et or near 1001 especitys veter 1983. In 1984. PNPS had no resulted in several (CBD) incidents at temperatures in the discharge were thermal component to induce noteworthy incidente of FNFS. as high so 30.5 C and dissolved CsD. This was also the CBD in fish at FNPg. gases were supersaturated (Nitrogen case from 1986-1988. Mortalities of 43.000
+ ergon esturation levels ranged and 5.000 adult men-
, irca 112-1191). An estimated 600 heden occurred in the silversides and 300 juvenile men- discharge in 1973 and haden were afflicted with CBD in 1975. respectively.
the discharge canals fish were Striped mullet schooling stressed.but mortality, which wee in the discharge were likely, was not evidenced. afflicted in late 1975. CBD can severely stresa or kill (outright or through incrossed susceptibility to dio-ease or predatica) fish residing in the heated discharge. l. L r ) l 1 i I' J 1
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j
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,V. CONCLUSIONS Lobster - Commercial Fisherv
- 1. The commercial catch rate of legal lobster (t 81.7% mm carapace length) la the discharge
! area (surveillance) in 1988 remained at 0.34/ trap-haul, while legal catch rate in the l control area increased 20% to 0.25.
- 2. Annuallegal catch rates in the discharge area, which have declined slightly from 1983-1987 (froun 0.47 in' 1983 to 0.34 in 1987) have not mirrored the fluctuating annual commercial catch rates in western Cape Cod Bay; annual legal catch rates from the control area have '
more closely reflected the annual Cape Cod Bay commercial catch rates. Lobster - Research Studv
- 1. The research lobster' trap study has been conducted for three years under conditions of reduced environmental stress from the power plant. No waste heat was released into the receiving waters, and at times there was little or no effluent current, whereas'at other times one of the two circulating water pumps was operated during the extended plant outage.The proper palring of a potentially impacted / treatment site 'with non-impacted / reference sites is imperative when assessing stress during plant operation. '
- 2. We have identified two parameters -catch rate and size composition - that offer promise for i
assessing impact of the waste-heat discharge from Pilgrim Station on the locallobster l population and fishery. As for size composition, size frequency data of legallobster at the l two reference area can be pooled and tested against size distribution data of legals la the discharge arca when the plant resumes operation. As to catch rate, we used the extended ( outage period at the plant as a baseline period to establish the relationship,in the form of a ratio, of catch rate at the impact site to that at the reference locations (mean of the two l areas). This ratio will be tested against operational data. laibore Groundfish
- 1. Anaval trawl catch / effort data of the three dominang groundflah - winter fleander,
( groundfish - winter flounder,little skate, and windowpane - were compared o rer the years ) 1983 through 1983 (included four outage years) between Station 1 (reference facatlon in Warren Core) anti Station 3 (Discharge area) to essess plant impact; there was no 1
E i ludication of a plant discharge effect on ti;e distribution of these species.
- 2. Winter flounder relative abundance was significantly less at the Intake (Station 6) than at two other stations la spring; conversely, this species was significantly more abundant in l
l the Intake than at any of the other stations in summer.
- 3. There was additional confirmation that the Intake is a seasonal haven for small winter flounder $23 cm; however,in 1988, the pulse of small flounder occurred in fall rather than I spring.
Pelsnic and Benthl-nelante Fishes ;
- 1. Atlantic herrirg abundance greatly increased in 1988; catch rate was the highest recorded for this species. Catch rate of pollock increased from 1987. Overall cunner abundance for the period 1984-1988 exhibited a marked decline.
- 2. A significant positive correlation (r =0.620; P >0.05) was found when cunner CPUE and seasonal MDC were tested. Regression analysis of catch rate on seasonal plant capacity yielded a highly significant F ratio (Fs = 9.38; P 5 0.05). Thirty - eight percent of variability in cunner CPUE can be explained by variations in MDC.
- 3. Because cunner are attracted to the discharge, they are at risk from potential near-fleid effects, e.g. thermal stress and chlorine toxicity.
Shore-rone Fish _gi
- 1. The Pilgrim Intake, a man-made embayment,is a microcosm of a naturally formed bay and has proven to be a haven for shore- zone fish in an otherwise open coastal region.
2.Of the sampling stations, Pilgrim Intake most resembled the estuarine sampling site of f Long Point in habitat (both have vegetative cover and protection from unchecked waves) and resultant haul seine catches of there-zone fishes relatlee to species diversity, total catch, and catch rater.
- 3. Fish concentrations in the Intake, especially In proximity to the intake screen wall, are uubject to mechanical eff ects of power plaat operation.
!)nderwater Finthb_Q_I dena.!Jan_t I 1. Project divets experienced difficulty distinguishing between denuded and stunted zones due I
I 33
to renewed growth of Irish moss in the discharge area.
- 2. Observed fish were distributed fairly evenly between the discharge (50%) and control (45%)
zones. Occurrence la the stunted zone (5%) was the lowest recorded. Species diversity and composition were similar to recent years.
- 3. Cunner abundance lacreased from 1987; they were most of ten foun,i in the discharge area.
. Pollock ranked second, being found primarily la the control area, and tautog were third, found u.ostly la the discharge area.
SR9Li . 5
- 1. Angling activity (fishing effort) and resultsi.s yartfish catches at the Pilgrim Station Shorefront recreation area declined further in 1988 from the previous lows of 1987.
- 2. Poor fishing was clearly linked to the station outage, i.e. the absence of a strong thermal i
current med its positive taxis for many fish has resulted in marked reductions of game fish i catches.
- 3. The concentration of fish in the waste-heat discharge, however, increaser the potential for stress or fish kills laduced by thermal stress, cold shock, or gas supersaturation. ..
I J ( Ii l j.
1 I VI. ACKNOWLEDGMENTS We acknowledge the contributions of numerous staff memabers of the Divislom of Marlee Fisheries (DMF), who assisted la varlons phases of data collection, computer programming, and data analysis, especially Joseph Battagila, Kevin Creighton, Theresa Ritchot, Virgista Fay, and Karen Bugley. We thank Chris Kyranos, commerciallobsterman, for allowleg as to sample ( his lobster catches, and Raymond Daud and Robert Ellenberger, Boston Edison (BECo) public relations' persommel, for gathering sportfish data at the Shorefront area. Also greatly q l appreciated is the work'of Kim Trotto of DMF for word-processing sections of this report. Flaally, we thank Robert D. Anderson, BECo Semlor Marine Fisheries Biologist, W. Leigh Bridges, Assistant Director of Research for DMF, and the Pilgrim Administrative-Technical Committee for their helpful suggestless and editorial cosaments while overseelag the entire study program. 1 g I , l I <- ,
' ^
,A. -
l g- l I 1 I l I . E ,
- _ _-____ _ ______- ___ A.
I' VII. LITER ATURE CITED Auster, P.J.1985. Fac' ors affecting catch of American lobster,Ilomarus americanus in balted traps. NOAA National Undersea Research; University of Connecticut, Groton, CT,46 pp. Bridges, W. L., and R. D. Anderson.1984. A brief survey of Pilgrim Nuclear Power Plant l effects upon the marine aquatic environment, p. 263-271. h: J.D. Davis and D. Merriman
/ editors), Observations on the ecology and biology of western Cape Cod Bay, Massachusetts, Springer-Verlag, Berlin, FRG,289 pp.
Campbell, A.1983. Growth of tagged lobsters (Ilomarus amerleanus) off Port Martland, Nova Scotia, 1948-80. Canadian Technical Report of Fisheries and Aquatic Sciences, No.1232.10 pp. Estrella, B.T.1985. Massachusetts coastal commercial trap sampling program May-November 1984. Mass. Div. Marine Fish., Boston, MA. 58 p. Estrella, B. T. and D. J. Mcklernan. 1986. Massachusetts coastal commercial lobster trap sampling program. May-November,1985. Commonwealth of Massachusetts Dept. of Fisherles, Wildlife, and Environmental Law Enforcement. Division of Marine Fisherles. m 74 pp. E. Green, J. M.1974. A local mass winter kill of cunners in Newfoundland. Can. Field Nat. 88: 96-97. Green, J. M.1975. Restricted movements and homing of the cunner, Tautocolabrus adsnersus (Walbaum) (Pisces: Labridae). Can. J. Zool. 53: 1427-1431. Kelly, B. C., V. J. Malkoski, S.J. Correia, R.P. Lawton, M. Borgatti, and B. IIollister. Ic88. Annual report on monitoring to assess impact of Pl! grim Nuclear Power Station on marine fisheries resources No. 44. h: Marine Ecology Studies Related to Operation a of Pilgrim Station. Semi-Annual Report No. 31. Boston Edison Company, Braintree, MA. g.. Keser, M., D. F. Landers, Jr., and J.D. Morris.1983. Population characteristics of the American lobster, liomarus americanus. In eastern Long Island Sound, Connecticut. NOAA Technical Report, NMFS SSRF-770. 7 pp. Lawton, R. P., P. Brady, C. Sheehan, M. Borgatti, and V. Malkoski.1983. A comparison of power plant Impingement with other types of sampling gear to survey flufish off Pligrim ! Nuclear Power Station. h: Marine Ecology Studies Related to Operation of Pilgrim lE Station. Semi-Annual Report No. 21. Boston Edison Company, Boston, MA. 9 pp. Lawton, R. P., G. Luders, M. Kaplan, P. Brady, C. Sheehan, W. Sides, E. Kouloheras, M. I' Borgatti, and V. Malkoski.1984. The Commercial lobster pot-catch fishery in the Plymouth vicinity, Westen Cape Cod Bay, p. 131-150. h: J.D. Davis and D. Merrimen (editors),0bsarvations on the ecology and biology of western Cape Cod Bay, Massachusetts, Springer-Verlag, Berlin, FRG. 289 pp. Lawton, R.P., C. Shichen, V. Malkoski, S. Cornela, and M. Borgatti.1985. Annval report on ' monitoring to assess impact of Pilgrim Nuclear Power Station H marir.e fishery resouncts of western Cape Ct,d Bay. Project Report No. 38 (Jan.-Dec.1984). h: Marine Ecology { Studies Related to Operation of Pilgrim Station, Semi-Annual Report No. 25. Boston Edison g Cornpany, Braintree, MA. j I 1 l ( l
1 l 1 Lawton, R. P., V. J. Malkoski, S. J. Correia, J. B. O'Gorman, and M. R. Borgatti.1986. Annual Report on monitoring to assess impact of Pilgrim Nuclear Power Station on marine fisheries resources of western Cape Cod Bay. Project Report No. 40 (Jan.-Dec.1985). In: Marine Ecology Studies Related to Operation of Pilgrim Station. Semi-Annual Report.27. Boston Edison Company, Braintree, MA. ' Lawton, R.P., V. Malkoski, S. Correia, B. Kelly, C. Sheehan, M. Borgatti, and P. Brady.1987. ! Final report on marine recreational fishing at the Pilgrim Station shorefront: 1973-1975,
;1983-1986. Pilgrim Nuclear Power Station Marlue Environmental Program Report Series No. 3 Boston Edison Company 53 pp. )j
' Lawton, R.P., B.C. Kelly, V.J. Malkoski, and M. Borgatti.1963. Annual report on monitoring to assess impact of The Pilgrim Nuclear Power Station on marine fisheries resources of - I western Cape Cod Bay (Imnact on Fisheries Resources). Project Report No. 44 (January- l December,1987). Summary Report No. 20 (Volume 2 of 2). In: Marine Ecology Studies 1 Related to the Operation of Pilgrim Station, semi-annual Report No. 31. Boston Edison '
Company, Boston, MA, USA. Lund, W.A., Jr., and G.C. Maltezos.1970. Movements and migrations of the bluefish (Pomatomus saltatrix) tagged in waters of New York and southern New England. Transactions of the American Fisheries Society 4: 719-725. Lyman, H.1974. Successful Bluefishing. International Marine Publishing Company. Camden, Maine.112 pp. Olla, B. L., A. J. Bejda, and A. D. Martin.1975. Activity, movements, and feeding behavior of the cunner, Tautomolabrus adsnersus. and comparison of food habits with young tautog, Tautoma onitis. off Long Island, New York. Fishery Bulletin. 73(4): 895-900. Sokal, R.R., and F. J. Rohlf.1969. Biometry: the principles and practice of statistics in biological research. W. H. Freeman and Company, San Francisco. 776 pp. Thomas, J. M., and P. Van Voris.1986. Statistical approaches for quantitatively assessing ecological Imract and riskr. Proceedings: Risk Assessment in Aquatic Ecology. 2-63 to 2-81. t ! Woolser, F., and H. Lyman.1983. Striped Bass Fishing. Nick Lyon Books, Winchester Press. 192 pp. ) r l l .
-37 y
i FINAL SEMI-ANNUAL REPORT Number 33-(Volume 1 of 2) to BOSTON EDISON COMPANY on BENTHIC ALGAL AND FAUNAL MONITORING AT THE PILGRIM NUCLEAR POWER STATION (CHARACTERIZATION OF BENTHIC COMMUNITIES) January - December 1988 By R. Eugene Ruff, Russell D. Winchell, Heather K. Trulli, Nancy A. Padell and Robert E. Hillman l L 0 l J 10 April 1989 l l BATTELLE Ocean Sciences ) 397 Washington Street j Duxbury, Massachusetts 02332 I
5 3 TABLE OF' CONTENTS Page EXE UTIy%
SUMMARY
........................................ il 2
~
INTRODUCTION............................................. METHODS.................................................. 3 RESULTS.......................(}......................... 6 FAUNAL. MONITORING................................... 6 Systematics.................................... 6 Species Richness............................... 6 s Faunal Density................................. 8 Species Dominance...............'.........'...... 9 Species Diversity.............................. 13 Measures of similarity......................... 14 ALGAL MONITORING.................................... 27 Algal Community Description.................... 27-Algal Community Overlap........................ '29 Al ga l- B i oma s s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Chondrus/Phyllophora Colonization Index Study.. 37 QUALITATIVE TRANSECT. SURVEY......................... '39 March 1988 Transect Survey..................... 39 June 1988 Transect survey 4.......~.............. 44 September 1988 Transect Survey................. 44 December 1988 Transect Survey.................. 45 HIGHLIGHTS OF RESULTS.................................... 45 FAUNAL MONITORING........e......... ................. 45 ALGAL MONITORING.................................. . 46 QUALITATIVE TRANSECT SURVSY,,............,........... 46 ACENOWLEDGEENTS.......................................... 47 E LITERATURE CITEb.........>............................... 47 l l 1 4 A _a_.____.______.-______..____.._ . _ - - _ _ _ _ _ _ - - - -
q. N
'J6 .
LIST OF TABLES-
. j.
4 -Page Table 1; Paunal Species Richness for March and [: September 1988.................................... 7 Table 2.- Faunal Densities at the Effluent, , Manomet Point, and Rocky Point Stations in March and September 1988....................... 8 Table 3'. Rank Order of Abundances for'the 15 Most Abundant Faunal'. Taxa in Samples. collected in March and September 1988.......................... 10 Table'4. . Diversity values for Each Station Sampled in
, March.and. September 1988.......................... 13 Table <5. ' Species Groups Identified by Inverse Cluster
. Analysis of March and September 1988 Data......... 22 Table 6. The Algal Species Used'in the Quantitative Community' Analyses................................ 28 Table 7. Average Dry weight Biomass per Replicate (g/m )
of Macroalgae at Manomet Point, Rocky Point, and Effluent Subtidal (10 f t. MLW) Stations in March 1988........................................ 33 Table 8. Average Dry Weight Biomass per Replicate'(g/m ) ; of Macroalgae at Manomet Point, Rocky Point, and _i
. Effluent Subtidal (10.ft. MLW) Stations in-September 1988.................................... 34 Table-9. Colonization Index values for Chondrus crispus !
and Phyllophora spp. for the Manomet Point, Rocky Point, and Effluent Subtidal (10 ft. MLW)' T Stations for March and September 1988............. 38 .; LIST OF FIGURES figure 1. Location of the Rocky Point, Effluent, and Manoret Point.Subtidal (10 ft. MLW) Stations...... 4 1 1 ' Figure 2. 'Dendrogram bhowing Results of Cluster Analysis of Data Using Bray-Curtis similarity and Group g Average Sorting................................... 15 t Figure 3. Dendrogram Showing Results of Cluster Analysis of Date Using Normalized Expected Species Shared (NESS) Similarity and Group Average Sorting....... 17 1 . . . . . .
I
' LIST OF' FIGURES (Continued).
Page Dendrogram Showing Results of Cluster Analysis of Figure 4. . . Combined March and September 1988 Data Using-Bray-Curtis Similarity and Group Average Sorting... 18 Figure 5. :Dendrogram Showing Results of Cluster Analysis of Combined-March and September Data Using NESS
. Similarity'and. Group Average. Sorting.............. 20 Figure 6. Dendragram Showing Results of_ Cluster Analysis of 50. Numerically Dominant Species From March-and September 1938 Samples Using Bray-Curtis Similarity and Group Average Sorting.............. -21
' Figure 7. . Constancy Diagram for Species Groups and
' Replicate Groups in 1988.......................... 24 Figure 8. . Fidelity Diagram-for Species Groups and 25
~
Replicate Groups in 1988........................... Figure 9. Algal' Community overlap (Jaccard's Coefficient of Community) and Number of Species Shared Between Replicate Fairs at the Manomet Point, Pocky' Point, and Effluent Subtidal' Stations (10 ft. MLW), March:1988.......................... 30 Figure 10. Algal Community Overlap (Jaccard's Coefficient of Community) and Number of Species Shared Between Replicate Pairs at'the Manomet Point, Rocky Point, and Effluents Subtidal Stations (10 ft. MLW), September 1988...................... 31 Figure 11. Mas ch 1988 Qualitative ' transect Survey .of the PNPS Acute Impact Zone off the Discharge Canal......... 40 Pigure 12. June 1988 Qualitative Transect Survey of the PNPS 41 I. cute. Impact Zone off the Discharge Canal......... Figure 13. September 1988 Qualitative Transect Survey of the 42 PNPS Acute Impact Zone off the Discharge Canal.... 1 l rigure 14. December 1988 Qualitative Transect Survey of the 43 PNPS Acute Impact Zone off the Discharge Canal.... LIST OF PLATES Plate 1. Aerial view of the Rocky Point and Effluent Quantitative Sampling Stations.................... 5 Plate 2. Aerial View of the Manomet Point Quantitative 5 Sampling Station.................................. iii
_= e I i
.5:
' EXECUTIVE
SUMMARY
LThis. report presents the results- of the 1988 benthic monitoring surveys at the Pilgrim Nuclear Power Station (PNPS). The surveys are part of a long-term monitoring effort by Boston
' Edison Company (BECO)- to assess the impact of the thermal effluent ~ on the inshore benthic community. . Volume 1 of this report characterizes the benthic environment and its seasonal changes in 1988. Methods and procedures follow guidelines established by the Pilgrim Administrative Technical Committee (PATC)~and adopted by BECO as modified in 1981.
'The habitats and their algal and faunal communities found at the Manomet Point, Rocky Point, and Effluent. subtidal stations are: typical of shallow, exposed areas in western Cape Cod Bay. The rocky. substrata characteristic of ell three stations are covered with dense macroalgal communities typically dominated by Chondrus crispus and Phyllophora spp. This algal turf has created a habitat suitable for diverse faunal communities. In .past years, faunal species at all three sampling stations have numbered from 50 to more than 100, and 4 6 total faunal densities have ranged from 10 to 10 individuals per square meter. In contrast to the results of recent years, the faunal communities during 1988 were dominated by the mussel Mytilus edulis. The results of this study indicate that faunal species richness, faunal densities, faunal diversity, and total algal biomass- in western Cape Cod Bay exhibit seasonal cycles, with low values in spring fo31 owed by high values in fall.
1 I, I
INTRODUCTION This report presents, in a condensed format, the results of the 1988- benthic monitoring surveys-performed at the Pilgrim Nuclear Power Station (PNPS) under Purchase order #65218 to Battelle Ocean Sciences. Detailed technical informationuis available from Battelle Ocean Sciences upon request through Boston Edison Company. The report is divided into two volumes. Volume 1 characterizes the benthic environment and its seasonal changes in 1988; Volume 2 discusses the impact of the PNPS
' operations on the benthic communities based on the observations described in volume 1 and in comparison to earlier observations (1983 to 1987). This format makes the results more accessible to readers who are more interested in overall results than technical details.
PNPS is ' located on the northwest shore of Cape Cod Eay, 8 km (5 miles) southeast of Plymouth Harbor, Massachusetts. The quantitative algal and faunal data in this report were derived from field ' samplings in March and September 1988. Qualitative transect data were collected on March 16, June 15, September 27, and December 20, 1988. Although the sampling period extended through the ; continuing outage that began in April 1986, the circulating water pumps operated periodically. During 1988, only one pump , (either- pump "A" ot pump "B") operated at any ene time (Marine ! 4 Biocontrol Corporation, 1988). From January through June, a pump operated, on a monthly basis, between 19 and 74 percent of the time with negligible operation during April and May. In July, pump operation increased to 97 percent; thereafter, a pump l operated 100 percent of the time. As a result of this limited - circulating water pump activity, current eeneration was reduced at the Effluent station during 1988. l l 2
METHODS The methods and procedures follow guidelines established by Pilgrim Administrative Technical Committee (PATC) and the adopted by Boston Edison Company (BECO) as modified in 1981 (Boston Edison Co., 1987a). Methods that pertain to this report are fully described in Semi-Annual Report No. 29, Volume 1 (Boston Edison Co., 1987a). 2 As in previous samplings, five replicate 0.1089-m benthic samples were collected with SCUBA at the Effluent station and the two reference stations at Manomet' Point and Rocky Point. (Figure 1, Plates 1 and 2). Quantitative samples were preserved in the field and returned to the laboratory, where faunal and algal fractions were separated and analyzed. During the September 1988 survey, problems were encountered in collecting ! one of the replicates from the Rocky Point station; as a result, only four replicates from that station were processed. Quantitative data were analyzed on the Battelle VAX system using previously used to analyze PNPS benthic data. software were collected using a fixed line Qualitative transect data stretched offshore along the discharge canal center line and a placed perpendicular to the fixed line. Divers movable line traversed the transect noting the boundaries of the stunted and denuded Chondrus (Irish moss) zones that extend offshore from the effluent canal. l ) 3
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b u. RESULTS FAUNAL MONITORING Systematics During 1988, six species were added to the list of benthic invertebrates recorded at PNPS. These were the amphipod Janira alta, the isopod Chirodotea sp. 1, the mollusc Acmaeidae sp. 1, and the polychaetes Pectinaria granulata, Polydora quadrilobata,
.and Scalibregma inflatum. The three polychaete species are known to occur -in Cape Cod Bay, usually associated with muddy sediments. During. this' program, 472 invertebrate species have been observed at the three monitoring stations sampled.
Species Richness Species. richness is- an index of the relationship of the number of species at a given site to- the total number of individuals at that site. Table 1 shows the numbers of invertebrate species found at each station in March and September 1988. The fewest species (47) were found at the , Effluent station during the spring sampling. This is more f species than collected at the Effluent in March 1987 (36), but fewer than observed at the two reference stations (61 and 62). By September 1988 the faunal community at the Effluent had changed significantly. The number of species increased to 61, which was similar to the numbers found at the two reference stations (63 and 65). The number of species at Manomet Point 3 and Rocky Point have remained about the same since September I 1987. The lowest estimated species richness (S) was in March 1988 at the Effluent station, but by September the differences between stations were minimal. In 1988, species richness did not differ significantly among stations, indicated by the overlapping 97.5 percent confidence intervals. 6 ,
TABLE 1. FAUNAL SPECIES RICHNESS FOR MARCH AND SEPTEMBER 1988. Number of Species Richness Variance Station / Month Species (S) (S)(197.5% CI) (var (S)) Effluent March 47 61.4 ( 11.96) 18.56 September 61 70.6 (: 9.68) 12.16 Manomet Point March 61 73.8 ( 4.15) 2.24 September 63 68.6 ( 8.31) 8.96 Rocky Point March 62 71.6 ( 5.66) 4.16 September 65 72.2 ( 11.67) 13.44 CI - confidence interval. The variance of the estimated species richness (var (S)) is a measure of the spatial distribution of species that occur in only one replicate from a station, referred to as " unique" species. High var ($) values indicate that all unique species at a station are concentrated in a small area at a station; low i values indicate the unique species are randomly distributed over the area sampled by the replicates. High var ($) values were found only at the Effluent station in March, while the values at the reference stations were very low. By September, these values had dropped at the Effluent station and increased at the reference stations, indicating the communities at the three stations had become more similar in distribution of unique species. , 7 f
Faunal Density 2 Benthic macrofaunal- abundances (individuals /m ) were calculated for total taxa, including juveniles and damaged specimens which could not be identified to species (indeterminate), for both sampling periods (Table 2). In March, mean density at the Effluent was less than half of that found at the Manomet Point and Rocky Point reference stations. By September, however, the mean density at the Effluent was the highest. Mean densities increased from spring to fall at all three stations, and ranged from a 31 percent increase at Rocky Point to a 470 percent increase at the Effluent. Most of the increase in faunal density at all stations could be directly attributed to the blue mussel Mytilus edulis. When this species was excluded from the calculations, the total abundance of all other organisms still showed an increase between the spring and fall sampling periods, but the percent increase at each station was lower. The increase was most pronounced at the Effluent station, where abundances excluding 2 Mytilus rose from 32,323 to nearly 98,000 individuals /m , TABLE 2. FAUNAL DENSITIES AT THE EFFLUENT, MANOMET POINT, AND ROCKY POINT STATIONS IN MARCH AND SEPTEMBER 1988. Mean Number of Numberof{ndiv. Numberof}ndiv. Individuals per per m per m Replicate (Mytilus included) (Mytilus excluded) Mar Sep Mar Sep Mar Sep Effluent 7,517 42,857 69,025 393,545 32,323 97,895 Manomet Point 18,238 41,126 167,475 377,649 79,860 105,513 Rocky Point 15,951 20,940 146,476 192,287 55,625 92,057 I I
Species Dominance The 15 numerically dominant species at each station were determined using tha mean number of identified individuals per replicate (Table 3). For this analysis, the juveniles and indeterminate were excluded since species determinations could not be made. The dominant species at each station during each sampling period was Mytilus edulis, which accounted for over half .the collected fauna. Most of the remaining dominant taxa at the three stations were arthropods, as has been found at these rocky subtidal locations in the past. The polychaete Nicolea zostericola was also a dominant during both samplings. During March, 10 of the 15 dominant species at Manomet Point, and-9 of the 15 dominants at Rocky Point were also found
~
at the Effluent. The two reference stations had 12 species in common, with the 6 top dominant species being identical at each station. These same 6 species were among the 7 top dominant species at the Effluent. The 15 dominant species contributed approximately 99 percent of the total identifiable fauna at the Effluent, 97 percent at Manomet Point, and 96 percent at Rocky Point. In September, the Effluent and Manomet Point stations again l shared 10 of the 15 dominant species. Eleven of the 15 were found at both the Effluent and Rocky Point sites, and the two reference stations had 11 taxa in common. The 9 most abundant species were the same at the reference stations, although the ! rankings differed. Seven of these 9 were among the 10 most common species at the Effluent. During the fall, the 15 dominants contributed approximately 99 percent of the total identified fauna at the Effluent station, and 96 and 93 percent l at Manomet Point and Rocky Point, respectively. Both similarities and seasonal changes at the three stations were evident when the dominant species for each sampling period were compared. The mussel Mytilus edulis was numerically dominant at all stations during both sampling periods, with abundances increasing considerably from March to 9
TAsu 3. atJIK cmDER ol' 'aIE 15 MosT A-=r PAtalhL TAEA In sanPus rnr.r2CTED IN MhblOR AM sEFFEFEIER 1988. Msen Percent of Number per Identified statioWapecies Replicate Pauna MhaQt 1988 Effluent
*Mytilus edulis (Bivalve) 3996.8 60.63 calliopius laeviseulus (Amphipod) 1007.2 15.33
*Pontogeneia inermis (Amphipod) 490.4 7.46
*IJeuna vincts (Gastropod) 346.4 5.27
*2schyrocerus anguipes (Amphipod) 336.8 5.13
*Jassa falcata (Amphipod) 88.8 1.35
*Demanine t y (Amphipod) 44.8 0.68
'*2dotea phosphorea (Isopod) 43.2 0.66
*Proboloides holmesi (Amphipod) 36.8 0.56 cancer irroratus (Decapod) 28.0' O.43
*corophium bonelli (Amphipod) 20.8 0.32 capre11a penantis (caprellid) 17.6 0.27 Anomia simplex (Bivalve) 15.2 0.23 Paqurus sp. 1 (Decapod) 13.6 0.21
*corophium acutum (Amphipod) 11.2 0.17 Total of 15 species 6497.6 98.90 Remaining Fauna - 32 species 72.8 1.10 Total Identified rauna - 47 species 6570.4 100.00
> - t Point
*Mytilus edulis (Bivalve) 9541.6 57.90
*Jassa falcata (Amphipod) 1352.8 6.21
*2schyrocerus anguipes (Amphipod) 1285.6 1.80 Pontogeneta inermis (Amphipod) 903.2 5.48
*1acuna vincta (Gastropod) 851.2 5.17
*Demanine thea (Amphipod) 460.0 2.79
*corophium bonelli (Amphipod) 401.6 2.44
*corophium acutum (Amphipod) 356.8 2.17 Proboloides holmesi (Amphipod) 217.6 1.32 l
*Pleusyntes glaber (Amphipod) 108.8 1.02 l
*onoba seules (Gastropod) 153.6 0,93
*Margerates helicinus (Gastropod) 120.8 0.73 capre11a penantis (caprellid) 90.4 0.55 )
corophium insidiosum (Amphipod) 65.6 0.40 l
*Amphithee rubricata (Amphipod) 53.6 0.33 I Total of 15 species 16,023.2 97.24 Remaining Fauna - 46 species 456.8 2.76 Total Identified rauna - 61 species 16,480.0 100.00 Rocky Point
*Mytilus edulis (Bivalve) 9893.6 67.25
*2schyrocerus anguipes (Amphipod) 1226.4 8.34
'Jassa falcato (Amphipod) 903.2 d.14
*1Acuna vineta (Gastropod) 632.8 4.30
*Pontogeneia inermis (Amphipod) 192.0 1.31
*Demasune g (Amphipod) 176.0 1.ID
*Margarttes helicinus (Gastropod) 175.2 1.19
*corophium bonelli (Amphipod) 172.8 1.17
*Nicolea sostericola (Polychaete) 150.4 1.02
*onoba acules (Gastropod) 144.8 0.98 Proboloides holmesi (Amphipod) 120.8 0.82
*Pleusymtes glaber (Amphipod) 111.2 0.76
*corophium acutum (Amphipod) 107.2 0.73
*Alvania pseudoareolata (Gastropod) $4.0 0.57 Motopella angusta (Amphipod) 74.4 0.51 Total of 15 species 14,164.8 96.29 Remaining rauna - 47 species $47.2 3.71 Total Identified Fauna - 62 species 14,712.0 100.00 l
10
l TAar2 3. (continued) staan Percent of member per Identified Station /Specise Replicate Fauna sErfEMasm 1968 Effluent .
*Mytilus edulis (Bivalve) 32196.0 78.04
- Lacuna vincta (Gastropod) 2535.2 6.14
*Jassa falcata (Amphipod) 1420.0 3.44 Hiatella arctica (Bivalve) 1152.8 2.79
*Dexamine thea (Amphipod)' 614.4 1.49 Hastella striata (Bivalve) 529.6 1.28
*corophium bonelli (Amphipod) 472.0 1.14
*Ischyrocerus anguipes ( Amp:iipod) 398.4 0.97
*Idotes phosphorea (Isopod) 325.6 0.79 Pleusyntes glaber ( Amphipoda) 295.2 0.12 crepidula fornicata (Gastropoda) 263.2 0.64 Onchidoras espera (Rudibranchia) 144.8 0.35
*Corophium acutum (Amphipod) 140.8 0.34
*Pontogeneia inermis ( Amphipod) 81.6 0.20
*Proboloides holmesa (Amphipod) 80.8 0.20 Total of 15 species 40,650.4 98.53 Remaining rauna -- 46 species 607.2 1.47 Total Identified Fauna -- 61 species 41.257.6 100.00 Menomet Point
*Mytilus edulis (Bivalve) 29635.2 75.17 Hiatelle arctica (Bivalve) 2340.0 5.94
- Lacuna vincts (Gastropod) 2336.0 5.93
*Margarites helicinus (Gastropod) 623.2 1.58
*Jassa falcata (Amphipod) 609.6 1.55
*Pleusyntes glaber ( Amphipod) 588.0 1.49 1
*Dexamine thea (Amphipod) 351.2 0.89
*onoba seulea (Gastropod) 326.4 0.83
*corophium bonelli ( Asphipod) 243.2 0.62 Nicolen sostricola (polychaeta) 208.8 0.53
*Ischyrocerus anguipes (Amphipod) 206.4 0.52
*corophium acutum IAmphipod) 144.8 0.37 l *Amphithoe rubricata (Amphipod) 142.4 0.36 l capre11a linearts (caprellid) 110.4 0.28 l Idotes phosphorea (Isopoda) 96.8 0.25 Total of 15 species 37.962.4 96.36 Remaining rauna -- 48 species 1461.6 3.69 Total Identified rauna -- 63 species 39,424.0 100.00 i
Rocky Point j i
*Mytilus edulis (Bivalve) 10915.0 59.12 l Haate11a arctica (Bivalve) 1841.0 9.97 I
- Lacuna vineta (Gastropod) 989.0 5.36
*Margarites helicinus (Gastropod) 797.0 4.32
( *ocoba aculea (Gastropod) 587.0 3.18
*Pleusyntes glabor (Amphipod) 442.0 2.39 l *Desamine thea (Amphipod) 263.0 1.42 ;
'Jassa falcata (Amphiped) 224.0 1.21
*Corophium bonelli (Amphipod) 219.0 1.19 ,
'Alvania pseudoareolata (Gastropod) 191.0 1.03 j
*corophium acutum ( Amphipod) 175.0 0.95
*Ischyrocerus anguipes ( Amphipod) 170.0 0.92
*Nicolen zosterscola (Polychaete) 150.0 0.81
/ crepidula fornacata (Gastropoda) 136.0 0.74
*Pontogeneta inermis (Amphipod) 130.0 0.70
/
/
/ Total of 15 species 17.229.0 93.31 8
Remaining rauna -- 50 species 1234.0 6.69 Total Identified rauna -- 65 species 18,463.0 100.00 Dominant taxa common to Lotn March ano september samples. 11
I September. Other species common to all stations during both I sampling periods included one gastropod (Lacuna vincta) and five amphipods (Ischyrocerus anguipes, Jassa falcata, Dexamine thea, Corophium bonelli, and C. acutum). Generally, in September the g amphipods were a less significant component of the fauna and 5 molluscs increased in dominance. At the Ef fluer.t , 10 species that were dominant in March s remained so in the fall. A noticeable change involved the amphipod calliopius laevisculus, the second most abundant species in narch, which was not among the dominants in September. The molluscs Hiatella arctica and H. striata, rarely collected in March, ranked fourth and sixth respectively in the fall samples. Molluscs increased in abundance at the Effluent and included three of the five numerically dominant species collected in September. Two decapods found as dominant species in the spring did not appear as dominants in the fall. Of the 10 species dominant both spring and fall, 9 increased in abundance in the fall. Four amphipods increased more than 10-fold. Only one amphipod, Pontogeneia inermis, decreased in abundance between spring and fall at the Effluent. At Manomet Point, 11 species were dominant in both spring and fall collections. The amphipods Pontogeneia inermis and i Proboloides holmsei were dominant in spring but were not among the top 15 dominants in the fall. The bivalve Hiatella arctica and the polychaete Nicolea zostericola were among the top 15 dominant species in the fall. At Manomet Point, only 6 of the 11 species found in common among all stations increased in abundance from spring to fall. The molluscs represented 4 of the 5 most abundant species during the fall, and increased from g 65 percent of the total fauna in March to 88 percent of the a total fauna in September. At Rocky Point, 13 of the 15 dominants were the same in March and September. Nine of the 13 species increased in abundance, 3 decreased, and 1 stayed about the same. In the spring, molluscs were 2 of the 5 numerically dominant species, but by fall all 5 positions were occupied by molluscs. 12 l
Species Diversity Species diversity is a measure of the species richness combined wzth the distribution of population size of each species (evenness). In general, low evenness values indicate that a community is dominated by one or a few species (Levinton, l Communities with high diversity are normally not 1982). stressed. Shannon-Wiener diversity (H') and evenness (J') (Levinton, 1982) were calculated from samples collected in March and September 1988 (Table 4). Juveniles and individuals not identified to species were excluded from the calculations. As in past years, the lowest diversity (H') was found at the Effluent during both the spring and fall sampling periods. From March to September 1988, diversity increased at Rocky Point and decreased at the Effluent and Manomet Point stations. The highest diversity for the year was found at Rocky Point in September. To facilitate comparisons with data from previous years, Mytilus edulis was excluded from 1988 statistical analyses due 1 TABLE 4. DIVERSITY VALUES FOR EACH STATION' SAMPLED IN MARCH AND SEPTEMBER 1988. I March 1988 September 1988 , I With Without With Without Mytilus Mytilus Mytilus Mytilus Station H' J' B' J' B' J' B' J' i I Effluent 2.06 0.37 2.78 0.50 1.55 0.26 3.61 0.61 Manomet Point 2.52 0.42 3.65 0.62 1.78 0.30 3.90 0.65 Rocky Point 2.16 0.36 3.82 0.64 2.66 0.44 4.12 0.69 H' = Shannon-Viener diversity. J' = evenness. f 13 f
to the species' high abundance relative to the abundances of all other reported species. Statistical analysis excluding Mytilus resulted in higher Shannon-Wiener diversity values and evenness at all stations during both seasons. However, values at the Effluent were still lower than those at the reference stations, and the highest values were found at Rocky Point. l Measures of Similarity
- Similarity analysis followed by cluster analysis (Boesch, 1977) was used to address the following questions about benthic community structure at the three stations sampled in 1988
e Does the benthic community at the Effluent station differ from the communities at the reference stations? e Do seasonal changes of the benthic community at the Effluent station differ from those at the reference stations? ; o If there are differences in species composition and/or seasonality, which 4 species cause these differences? l To answer these questions, similarity analyses were j performed using two measures: Bray-Curtis (Boesch, 1977) and the Normalized Expected Species Shared (NESS) (Grassle and Smith, 1976). These measures were used to elucidate community patterns for 1) normal cluster analysis, where all replicate samples taken in 1988 were compared for the species present in each l replicate, and for 2) inverse cluster analysis, where the co-occurrence of the top 50 numerically dominant species identified in the 1988 samples was compared. l Normal Analysis i The results of the Bray-Curtis similarity analysis for the spring samples are shown in Figure 2A. Three major groups, each 14 f
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I E of which include replicates from only one station, which cluster the replicates from each station were apparent. The reference stations were very similar to each other and clustered together at the 0.76 level. The reference stations were more similar to g each other than they were to the Effluent group; the reference 5 stations and the Effluent station were joined at the O'.56 similarity level. By fall, the replicates no longer clustered into distinct station groups (Figure 2B). The analysis resulted in a dendrogram that showed similarities greater between replicates taken at different stations than between the replicates taken at the same station. Replicates taken at the Effluent and Manomet Point stations were highly similar to each other in terms of community composition. Much of the sample similarity could be attributed to the influence of the dominant mussel Mytilus edulis. To minimize this influence, NESS, a similarity measure that is more sensitive to rare species, was used (Figure 3). The dendrograms for March and September were very similar, with the replicate samples at the Effluent station forming discrete clusters. The g replicates at the two reference stations were very similar to B each other during both sampling periods and did not form distinct station groups. A normal cluster analysis of the combined spring and fall data (a total of 29 samples) was performed to examine the data for seasonal patterns (Figure 4). The replicates did not cluster into clear groups that would have indicated strong seasonal differences in species composition at each station. For example, Rocky Point replicate 2 collected in March was more g similar to two Rocky Point replicates collected in September 5 than it was to the other replicates collected in March. Thus major differences in species composition did not occur between stations in March and September. The clusters were also different from those produced when spring and fall data were analyzed separately. I 16 l
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. B. SEPTEMBER 1988.
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4 When NESS is used on the combined data set, less emphasis is placed on the mussel populations, and more of a seasonal pattern emerges (Figure 5). The spring Effluent replicates cluster separately from the other stations, indicating a seasonal difference between spring and fall. The reference stations cluster at a higher similarity level indicating lower seasonal differences, though the March replicates still separate out from the September samples. Inverse Analysis The combined spring and fall 1988 data were analyzed by inverse clustering to investigate faunal patterns underlying the seasonal variations seen in Figures 4 and 5. The top 50 numerically dominant species were used, producing the dendrogram shown in Figure 6. Six species groups were identified in this analysis (Table 5). Group 1 contains 21 species, including 14 arthropods, 6 molluscs, and 1 polychaete. With the exception of the mollusc Mitrella lunata and the caprellid Capre11a nr. septentrionalis, all species of Group 1 were among the top 15 dominants of at least one station in 1988. Fourteen of the 21 were among the top dominants during both spring and fall. Group 2 contains 18 species, including three arthropods, seven molluscs, six polychaetes, and two echinoderms. Only six of these species were among the top 15 dominants of at least one station in 1988. Group 3 is comprised of three polychaetes, two molluscs, and an echinoderm. None of these species were dominant at any of the stations sampled. 0;vup 4 includes two decapods; one of them, the rock crab Cancer irroratus, was among the top 15 dominants at the Effluent station in the spring. Group 5 is made up of the amphipod Phoxocephalus holbolli and the gastropod Alvania pseudoareolata. This gastropod was among the top 15 f dominants at Rocky Point in the spring. Group 6 contains only the Jonah crab cancer borealis, f 19
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Nodal Analysis Nodal analysis is a method to relate the groupings resulting from the normal cluster analysis (by replicate) and ) inverse analysis (by species) to enhance the interpretation of
'the resulting patterns (Boesch, 1977). Two measures, constancy and fidelity, are used.
Constancy is a measure of the frequency of a group of species in each group of replicate samples. The highest possible value is 1.0, indicating that all species of a species i group occurred in all replicates within a replicate group. The - lowest possible value is 0, indicating that no species of a species group occurred in any of the replicates within a replicate group. Constancy is a tool used to look for differences in species composition at different stations. When the same stations'are reoccupied at different times, constancy may be used to identify temporal changes. I Fidelity is an indication of the degree to which species are exclusively associated with the replicates in a particular group. Fidelity values are between 0 (all species of a species group are evenly distributed over all replicates) and >3 (all species of a species group occur in only one replicate). l Fidelity examines the spatial differences in the species composition at a group of stations and, when the same stations are reoccupied at different times, indicates the degree to which the species are limited to each collecting season. ! Results of the nodal analysis are presented in constancy and fidelity diagrams (Figures 7 and 8, respectively). Each ! diagram is composed of a species group dendrogram (across the I top), a site group dendrogram (to the left), and a resulting matrix. The species group dendrogram divides the 50 dominant species into six groups. The site group dendrogram, which included only those 50 species, generated four site groups corresponding to the Effluent and reference stations during each sampling period. The central part of the diagram is the matrix showing the intersection of each species group with each site 23 f
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group. The value at each intersection is shown by the shading, and .the width of each field of the matrix depends on the number of species or. replicate samples constituting the group. Figure 7 shows the constancy diagram of the six species groups for the four seasonal site groups.' Species group 1 shows high or very high constancy at all stations during both spring and fall. This result is expected because this group includes-most of the species that were among the 15 most common species at all three stations during both seasons. The organisms in species group 2 show a definite seasonal preference. In spring, constancy was low to moderate at the stations, indicating that the species in the' group were not found in all of the replicates. . By fall, however, constancy was very high at these stations, indicating all species of this group occurred regularly in all replicates. Species groups 3, 4, and 5 showed virtually no seasonal response, maintaining the same constancy values in March and September. Constancy was moderate for these species groups at i the reference stations during both seasons. Constancy was low to very low for_ species groups 3 and 5 at-the Effluent station, ; indicating a preference of these two species groups for the l reference stations. .The high to very high constancy values for . group 4 indicate a preference by these species for the Effluent site. The Jonah crab cancer borealis, the sole component of ! species group 6, exhibited a clear temporal pattern. The species was absent from the March samples, and occurred with low j to moderate constancy in September. In general, fidelity values for the six species groups at j the- four seasonal sites is low to very low (rigure 8), I indicating an overall suite of species that are found throughout the region and are not restricted to any particular site or season. The exception is the crab C. borealis (species group 6), which showed a definite preference for the Effluent station in the fall. 26
ALGAL MONITORING The habitats and associated algal and faunal communities found at the Manomet Point, Rocky Point, and Effluent subtidal stations have been well documented by Grocki (1984) and Davis and McGrath (1984) and are typical of shallow, exposed areas in western Cape Cod Bay. The rocky substrata characteristic of all three stations are covered with dense macroalgal communities typically dominated by two species of red algae (Rhodophyta), Chondrus crispus and Phyllophora spp. Table 6 includes the species identified in the 1988 samples. The table includes 37 indicator species (Boston Edison Co., 1988a) and two additional species. Algal Coe.munity Description The rock and cobble substrata found at Manomet Point, Rocky Point, and the Effluent were heavily colonized by red macroalgae during 1988. Biomass of Chondrus crispus was highest at Rocky Point in March and at the Effluent in September. Phyllophora 1 spp. biomass was highest at Manomet Point in March and at Rocky Point in September. The higher.t biomass of benthic species f other than Chondrus and Phyllophora occurred at the Effluent in March and at Rocky Point in September. The highest biomass of epiphytic algae was found at Manomet Point in March and at Rocky Point in September, whereas the lowest values were at the l Effluent in March and at Manomet Point in September. The primary hosts for epiphytes were Chondrus and Phyllophora, but l other benthic species, such as Polyides rotundus and Ahnfeltia plicata, also served as hosts for epiphytes. Red algae such as Spermothamnion repens, Polysiphonia fibrillosa, P. harveyi, and Ceramium rubrum were the most commonly observed epiphytes. The warm water indicator Gracillaria tikvahiae was neither sampled in 1988 nor observed within the stunted or denuded zones during the 1988 transect surveys. 27
TABLE 6. THE ALGAL SPECIES USED IN THE QUANTITATIVE COMMUNITY ANALYSES. SPECIES ARE INDICATOR SPECIES (TAXON, 1982) UNLESS NOTED OTHERWISE (*).
- s. - .
CHLOROPHYTA (green lgae) Bryopsis plumosa Enteromorpha flexuosa Chaetomorpha linum .Rhizoclonium riparium C. melagonium Ulva .lactuca Cladophora spp. juv.* PHAEOPHYTA (brown' algae) Chordaria flagelliformis** Laminaria digitata Desmarestia aculeata L. saccharina D. viridis ** Sphacelaria cirrosa RHODOPHYTA (red algae) ! Ahnfeltia plicata Phycodrys rubens Antithamnion americanum Phyllophora truncata rangia spp. juv.* P. pseudoceranoides Bonneraisonia hamifera P. p aillii** Callophyllis cristatA Plumaria elegans Ceramium rubrum Polyides rotundus ! Chondrus crispus Polysiphonia elongata Corallina officinalis P. fibrillosa j Cystoclonium purpureum P. harveyi Gracilaria tikvahiae** P. nigrescens ;
** i Gymnogongrus crenulatus P. urceolata !
Membraneptera alata Rhodomela confervoides
~Palmaria palmata Spermothamnion repens
- This species was not originally designated to be an indicator species.
** This species was not found in the 1988 data. {
i 28
'I I Algal Community overlap Community overlap was calculated for March and September 1988 data; Jaccard's coefficient of community structure (Grieg-Smith, 1964) was used to measure the similarity in algal cortposition between the Effluent, Manomet Point, and Rocky Point. This coefficient mathematically evaluates the similarity between two replicates or stations using species occurrence, and is not influenced by differences in abundance. occurrence records of the 39 algal species, including the indicator species (Table 6), were used for community overlap calculations. Results of community overlap comparisons between replicate I samples for each matrix station form for March (Figures 9 and and September 1988 are 10). In March, presented in community overlap was generally higher between the two reference stations (88.9 percent) than between either Manomet Point or Rocky Point and the Effluent station (01.5 and 85.2 percent, respectively). In September the reverse was seen. Community overlap was higher between the reference stations and the Effluent station (89.7 and 85.7 percent) and lower between the two reference stations (82.8 percent). This indicates that ,I in March the two reference stations were more similar to each other than they were to the Effluent, but in September both y r e f e re:.ce stations were more similar to the Effluent station than they were to each other. Overall, the similarity of all three stations was high (>80 percent in March and >82 percent in September), and the similarity of the Effluent station to the reference stations 4.ncreased from spring to fall. Replicate overlap ranges for the Effluent and Rocky Point were narrower in September than in March, indicating these two stations were more I similar to each other in September than in March. revers! was true for Manomet Point. However, the I I 29
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I E Algal Biomass Algal biomass usually shows a very regular seasonal pattern at all three stations, with biomass values being low in spring and high in fall (Boston Edison Co., 1987a). In 1986, and to a lesser extent in 1987, the pattern was atypical. In 1988, the typical pattern was reinstated except at the Manomet Point station, which decreased slightly in algal biomass in September. Biomass values for Chondrus crispus were calculated for the Effluent, Manomet Point, and Rocky Point in March and September 1988 (Tables 7 and 8, respectively). In March 1988 the mean replicate value for Chondrus biomass was highest at Rocky Point (133.92 g/m 2
) and lowest at the Effluent (27.34 g/m2). The mean g Chondrus biomass at Rocky Point was slightly higher than at 3 Manomet Point, and was almost 5 times that at the Effluent. The range of replicate biomass was greatest at Rocky Point (44.80 to 2
225.64 g/m2 ) and smallest at the Effluent (0.00 to 102.82 g/m ), Chondrus made up 10 percent of the algal biomass at the Effluent, followed by 36 percent at Mancmet Point, and 43 percent at Rocky Point. In September 1988, the highest mean Chondrus biomass per e replicate was observed at the Effluent (570.68 g/m2); values 2 were lowest at Manomet Point (277.60 g/m ). The mean Chondrus biomass at the Effluent was 75 percent higher than at Rocky Point. The greatest range of replicate biomass was found at the Effluent station (6.61 to 1457.23 g/m2); the lowest range was 2 calculated for Rocky Point (262.64 to 379.13 g/m ). Chondrus made up 81 percent of the total algal biomass at the Effluent, followed by 47 percent at Rocky Point and 86 percent at Manomet Point. Mean values of Phyllophora biomass measured in March and September 1988 are shown in Tables 7 and 8, respectively. In March, the mean Phy11ophora bior. ass per replicate was highest at 2 Manomet Point (163.04 g/m ) and lowest at Rocky Point (119.69 g/m ). Mean biomass at the Effluent was intermediate (133.07 2 g/m ). This value is 18 percent lower than that at Manomet 32 l
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, np SR i s EC n T P i c T mi ES mh PE I C at s R es 83755 0 6 572 8 194 73 9 PI e a 2 63 51 2 8 4 54 1 53 4 91 2 ET sm A o 08 006 5 2 _ 8 17 5 5274 6 3
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P r 8 6999 8 6 54 3 4 8 g e ( T sP u E p SC S O s mE y t I F 5NI Wi r css a m o 594 4 9 0501 1 9 08 55 7 0 6 3 1 2 4 7 066 9 - 1 2 9 2 6 5 02 3 61 3 8 2 4 6 66 76 6 8 6 0 rO r 7 7 1 6 4 2 4 3 50 7 . i P i 4 1 9 02 G m 2 23 3 2 2 3 3 2 3 3 294 2 5 d T 1 e _ s MED s e _ fi K c t o e . r IEmI t sp a s c at mo 8 i t on _ l n i E p i t E e o n b e l B B P i np A / o g t T n t 1 234 5 i P l2345 It n 1 234 5 E a m e a o e e i m y u MS t o k l a n c f == o t a t S M n E i 1 a
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I l Point and 11 percent higher than that at Rocky Point. The range of replicate biomass was greatest at Rocky Point (62.61 to 188.65 g/m ) and smallest at Manomet Point (148.90 to 181.21 g/m2). Phyllophora spp. comprised 50 percent of the total algal I biomass at the Effluent, whereas the algal biomass at the Manomet Point and Rocky Point reference stations included 44 and 38 percent Phyllophora, respectively. September samples showed the highest mean Phyllophora biomass per replicate at Rocky Point (119.57 g/m2) and the lowest values at Manomet Point (29.98 g/m2). The mean biomass at the Effluent was intermediate (89.45 g/m2). The biomass value at the Effluent was 25 percent lower than at Rocky Point, and 3 times higher than at Manomet Point. The greatest range of I replicate g/m2), and biomass was observed at Rocky Point (22.58 to 191.22 the smallest range was calculated for Manomet Point 2 (1.29 to 81.79 g/m ). Phyllophora spp. made up 13 percent of the total algal biomass at the Effluent, followed by 9 percent at Manomet Point and 17 percent at Rocky Point. A typical seasonal increase of Phyllophora biomass from spring to fall occurred at the Effluent and Rocky Point, whereas a decline was noted at Manomet Point. The seasonal variations of Phyllophora are thus similar to the variations observed for Chondrus. The algal biomass category designated " Remaining Benthic Species" is composed of all benthic algae excluding Chondrus crispus, Phyllophora spp., Laminaria spp., and algal epiphytes. Important benthic species were Cheetomorpha spp. at all stations, Phycodrys rubens at the reference stations, and I Polyides rotundus at the Effluent station. Tables 7 and 8 present mean replicate biomass values for the remaining benthic species (RBS). In March 1988, the highest I mean RBS biomass was found at the Effluent (86.02 g/m2) and in September, the highest values were found at Rocky Point (65.18 g/m2). The lowest mean RBS biomass was noted in both months at 2 Manomet Point (14.76 g/m in March, 5.20 g/m in September). The mean RBS biomass at Rocky Point was intermediate (14.94 35
I 2 2 g/m ) in March, and intermediate at the Effluent (33.29 g/m ) in September. The range of replicate biomass was greatest at the Effluent in March (12.76 to 134.40 g/m ) and in September (5.51 to 126.13 g/m2); the smallest range was observed in Rocky Point samples in March (0.46 to 62.15 g/m2) and in Manomet Point " samples in September (0.37 to 10.28 g/m2). The RBS comprised 32 percent of the total algal biomass at the Effluent in March and 5 percent .in September. The total algal biomass at Manomet Point included 4 percent RBS in March and 2 percent in September. In March at Rocky Point, the RBS made up 5 percent of the total algal biomass; in September it was 9 percent of the total. Tables 7 and 8 present mean replicate biomass values of epiphytic algae. As during most of the previous studies, Phyllophora spp. exhibited a higher degree of epiphytic colonization than Chondrus crispus. It has been hypothesized that the higher biomass of epiphytes associated with Phyllophora spp. a was due to the sturdier morphology of this species (Boston g Edison Co., 1986). In March 1988, the mean biomass values were highest at Manomet Point (60.55 g/m2), and in September, the highest values were at Rocky Point (179.26 g/m ). The lowest mean biomass values were found at the Effluent in March (19.94 2 5 g/m ) and at Manomet Point in September (9.94 g/m 2 ). In March, 5, epiphytic algal biomass at the Effluent was 67 percent lower than that at Manomet Point and 55 percent lower than at Rocky Point. In September, epiphytic algal biomass at the Effluent was 19 percent higher than at Manomet Point and 93 percent lower I than that at Rocky Point. Epiphytic algae at the Effluent made up 7 percent of the total algal biomass in March and 2 percent ; in September. The contribution of epiphytic algae to the total algal biomass Manomet Point and Rocky Point, was 16 and 14 at g percent, respectively, in March and 3 and 26 percent, B respectively, in September. At Rocky Point, epiphyte biomass increased from spring to fall and decreased at the Effluent and Manomet Point. I 36 '
l lE l !I Mean values for total algal biomass in March and September 1988 are shown in Tables 7 and 8, respectively. In March values at the Effluent were lowest among the three stations, and in I September values were highest. In March, total algal biomass at the Effluent was 28 percent lower than at Manomet Point and 15 percent lower than at Rocky Point; in September, total algal biomass at the Effluent was more than twice that at Manomet Point and 2 percent higher than at Rocky Point. Total algal biomass increased considerably from spring to fall at the Effluent and at the Rocky Point station. With the exception of 1986, this pattern has occurred each year since 1983 at these I stations . At Manomet Pe ~.t, however, biomass decreased slightly throughout the year and is now at a lower value than any measured since 1983. Chondrus/Phyllophora Colonization Index Study Colonization values are determined for the primary host species (Chondrus and Phyllophora) and are a qualitative measure algal epiphytes and invertebrate species I of the degree of present on the host species. Colonization index values are the summations of colonization values for algal and faunal colonizers. Details of the procedure are the same as presented in the Semi-Annual report No. 30 (Boston Edison Co., 1987b). Data from 1988 (Table 9) continue to indicate that upp.
~
Phyllophora were more heavily colonized by epiphytes than was Chondrus. This observation has been typical during most of the past samplings and, as noted earlier, is probably due to the denser frond developnient of Phyllophora spp. compared with I Chondrus. Generally, and highest at Manomet Point. colonization was lowest at the Effluent I l i l I ' I l 37 l
. TABLE 9. COLONIZATION INDEX VALUES FOR Chondrus crispus AND Phyllophora spp.
FOR THE MANOMET POINT, ROCKY POINT, AND EFFLUENT SUBTIDAL (10 FT. MLV) STATIONS FOR MARCH AND SEPTEMBER 1988. Manomet Point Rocky Point Effluent Mar- Sep Mar Sep Mar Sep Chondrus crispus Algal Colonization 12 6 12 8 3 5 Faunal Colonization 11 14 9 8 6 13 Total 23 20 21 16 9 18 Phyllophora spp. Algal Colonization 20 11 18 12 16 10 Faunal Colonization 19 17 19 12 14 14 1 Total 39 28 37 24 30 24 .l ( f i l 1 38
i I QUALITATIVE TRANSECT STUDY I Qualitative transect surveys of acute nearfield impact zones were initiated in January 1980 and have been conducted I quarterly since 1982. during 1988 (March 16, Four surveys of the area were performed June 15, September 27, and December 20) (Figures 11-14), bringing the number of surveys conducted to 32. Results of surveys conducted from 1980 through 1983 were summarized in Semi-Annual Report No. 22 to Boston Edison Company (Boston Edison Co., 1983). A detailed discussion of the March and June 1988 surveys can be found in Semi-Annual Report No. 32 I (Boston Edison Co., 1988b). These results will be summarized here along with new data from the September and December 1988 surveys. The denuded zone has been defined as being essentially ! devoid of Chondrus crispus, whereas the stunted zone was defined as having Chondrus of decreased size and density compared with conditions considered normal for this species. However, because of the increasing recolonization of the denuded and stunted zones during outage of PNPS, it became increasingly ] I the difficult to define these zones. The border between the stunted { 1 and denuded zones was no longer clear because of recolonization { by Chondrus resulting in patchy, thin growth in the formerly denuded zone. In 1988, boundaries could not be detected (Figure 11). As in 1987, no measurements of the size of the stunted and denuded zones were made. I March 1988 Transect Survey I Figure 11 illustrates the results of the divers' observations immediately offshore from PNPS on March 16, 1988. A large boulder that is nearly exposed at mean low water and used as a landmark by both the Battelle and Division of Marine Fisheries dive teams is plotted in the figure. The boulder i serves as a visual fix for the proper placement of the transect line and ensures consistency over che series of observations. 39
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Chondrus crispus was observed throughout the area that has been described as denuded of this species, depending on PNPS operating- characteristics. Transitions from denuded areas to areas of stunted or normal Chondrus growth were not clear, and no reliable areal measurements could be made. Only one small area to the northwest of the large boulder could be described as denuded of algae. Laminaria spp. were observed out to 50 m, and Fucus spp. were observed between 40 and 70 m along the transect line. June 1988 Transect Survey Based on the divers' observations on June 15, 1988, no denuded or stunted zones could be defined along the 90-m transect line (Figure 12). The small denuded area near the boulder was colonized by a sparse growth of algae. Although growth was sparse in some areas, Chondrus, Laminaria, and Fucus were present throughout the area. Rocks that had been bare of ] algae showed some Chondrus growth. Fucus and the coralline alga corallina were also present on some of the rocks out about 40 m along the transect line. September 1988 Transect Survey ] I Divers observations on September 27, 1988, revealed no denuded or stunted Chondrus growth. No clear boundaries could be defined (Figure 13) and no reliable measurements of the ( zones could be made. Although growth was sparse in some places, Chondrus and Laminaria were present throughout the area. Fucus spp. were present from 40 to 80 m along the transect zone, and l coverage was dense at 60 m. Codium was present et 60 m. The genera Ahnfeltia, Chaetomorpha, and Polysiphonia were present f along with Chondrus and Fucus at 80 m. l f l 44
l I 'I December 1988 Transect Survey I Transitions from denuded to stunted to normal Chondrus clearly be defined or reliably measured in I growth could not December 1988 because zone boundaries could not be detected (Figure 14). However, both Chondrus and Fucus coverage was reduced in comparison to the coverage observed during the September survey. This may be due to the natural winter decline in algal growth. The reduction in coverage was most apparent in the area previously described as denuded. Many of the rocks in I this Chondrus zone were nearly bare, although not completely denuded of or other species. Laminaria was prevalent throughout the survey area. I Although some boundaries were measured, they were not well defined. The term " sparse" has been substituted for the term
" stunted" because, although Chondrus was not prevalent, plants that were observed were apparently normal. Chondrus coverage appeared to increase in the area close to the mouth of the effluent (40-50 m on the transect line).
I f HIGHLIGHTS OF RESULTS FAUNAL MONITORING
- 1. 1988, species richness was lowest at the Effluent I
For station in March, but rose to the level of the reference stations by September. During March and September, none of the stations could be distinguished by species composition.
- 2. Faunal densities were lowest at the Effluent station in I March. Densities increased dramatically at all three stations from March to September, when the highest density was found at the Effluent. Much of the increase was due to the mussel Mytilus edulis.
,t 45
- 3. Mytilus edulis was the most abundant species at all
. stations during both seasons in 1988. All stations had similar dominant species during both March and September.
- 4. Species- diversity was lowest at the Effluent station during 'both the spring and fall. sampling period. Mytilus edulis constituted a large percentage of the total fauna at each site. When Mytilus was removed from the analysis, the diversity increased from March to September at all stations.
.5. Similarity was high between the samples taken at the-Manomet Point and Rocky Point reference stations in March.
Because of the dominance of Mytilus edulis, all stations were very similar in September.
- 6. Seasonality- in community structure was detectable at all stations. However, the significance of seasonality was muted by high abundances of a few species during both sampling periods.
ALGAL MONITORING
- 1. In. March, community overlap was highest between the two <
reference stations and lowest between either reference station and the Effluent station. In September,' community overlap was highest between both reference stations and . the Effluent station, and lowest between the two reference : stations, indicating a return to undisturbed environmental I conditions-at the Effluent.
- 2. Total algal biomass for 1988 increased dramatically from -(
spring to fall at Rocky Point and the Effluent. A slight decline was observed at Manomet Point.
- 3. Colonization Index values were generally higher for both algal and faunal epiphytes in March than in September, excluding epiphytic growth on Chondrus . crispus at the ,
Effluent. Due to its denser frond development, i j Phyllophora spp. was more heavily colonized by epiphytes f than was Chondrus. j l QUALITATIVE TRANSECT SURVEY Recolonization of the Effluent station increased in 1988. No clear boundaries separating denuded, stunted, and 1 normal zones could be defined, and no reliable measurement I could be made. 1 l 46 k
( / I ACKNOWLEDGMENTS Battelle's Project Managers for the algal and faunal I investigations were Ms. Tracy Stenner and Dr. James A. Blake during the first half of 1988, and Dr. Nancy J. Maciolek for the l rest of the year. Algal identifications were carried out by Ms. Brenda Cavicchi., Ms. Heather Trulli, Ms. Nancy Padell, and Mr. Russell Winchell, assisted by Ms. Judith Scanlon. Faunal identifications were made by Ms. Padell and Mr. Winchell, l supervised by Mr. Eugene Ruff. Field sampling was coordinated by Mr. John Williams. The field team included Mr. Robert Williams, Mr. Thomas Angell, and Mr. Ruff. Ms. Ellen Baptiste I ran the statistical programs. Dr. Robert E. Hillman, Dr. Brigitte Hilbig, Mr. Ste"en Mellenthien, Mr. Phillip Nimeskern, and Ms. Barbara Greene also participated in this project. l I LITERATURE CITED Boesch, D.F. 1977. Application of numerical classification in ecological investigations of water pollution. U.S. I Department of Commerce, NTIS PB-269 604. EPA-60013-77-033. 114 pp.
^
I Boston Edison Co. 1980. Marine ecology studies related to operation of Pilgrim Station. Semi-Annual Report No. 16. Boston, MA. Boston Edison Co. 1983. Marine ecology studies related to operation of Pilgrim Station. Semi-Annual Report No. 22. Boston, MA. i Boston Edison Co. 1986. Marine ecology studies related to l operation of Pilgrim Station. Semi-Annual Report No. 27. l Boston, MA. Boston Edison Co. 1987a. Marine ecology studies related to operation of Pilgrim Station. Semi-Annual Report No. 29. I Boston, MA. 47 l
l l l l Boston Edison Co. 1987b. Marine ecology studies related to operation of Pilgrim Station. Semi-Annual Report No. 30. Boston, MA. Boston Edison Co. 1988a. Marine ecology studies related to l operation of Pilgrim Station. Semi-Annual Report No. 31. l Boston, MA. Boston Edison Co. 1988b. Marine ecology studies related to operation of Pilgrim Station. Semi-Annual Report No. 32. Boston, MA. Davis, J.D. and R.A. McGrath. 1984. Some aspects of nearshore benthic macrofauna in western Cape Cod Bay. In: J.D. Davis and D. MeLriman (eds.). Observations on the Ecology and Biology of Western Cape Cod Bay, Massachusetts. Springer-Verlag, New York. 228 pp. Grassle, J.F. and W.L. Smith. 1976. A similarity measure sensitive to the contribution of rare species and its use in investigation of variation in marine benthic communities. 0ecologia 25:13-22. Grieg-Smith, P. 1964. Quantitative Plant Ecology. 2nd Ed. Butterworths, Washington. 256 pp. Grocki, W. 1984. Some aspects of nearshore benthic macrofauna in western Cape Cod Bay. In: J.D. Davis and D. Merriman (eds.). Observations on the Ecology and Biology of Western ! Cape Cod Bay, Massachusetts. Springer-Verlag, New York. i 228 pp. Levinton, J.S. 1982. Marine Ecology. 525 pp. Prentice-Hall k Inc. NJ. Marine Biocontrol Corporation. 1988. Pilgrim Station Chlorine and Biofouling Monitoring Program, Monthly Status Report, December 1988. Submitted to Boston Edison Co. Boston, MA. Taxon. 1982. Benthic studies in the vicinity of Pilgrim i Station. In: Marine ecology studies related to operation of Pilgrim Station. Semi-Annual Report No. 19. j l i
)
i
)
f 48
ll FINAL SEMI-ANNUAL REPORT l l Number 33 (Volume 2 of 2) to BOSTON EDISON COMPANY on BENTHIC ALGAL AND FAUNAL MONITORING AT THE PILGRIM NUCLEAR POWER STATION' (IMPACT ON BENTHIC COMMUNITIES) January - December 1988 By Nancy A. Padell, Heather K. Trulli, Russell D. Winchell, R. Eugene Ruff, and Robert E. Hillman i 10 April 1989 i l' BATTELLE Ocean Sciences 397 Washington Street Duxbury, Massachusetts 02332
TABLE OF CONTENTS Page g ExE cUTI vE e UM ARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 INTRODUCTION............................................ 2 I METHODS................................................. BACKGROUND.............................................. 4 7 i QUANTITATIVE FAUNAL COMMUNITY MONITORING................ 10 SPECIES RICHNESS................................... 10 FAUNAL DENSITY..................................... 12 l SPECIES DOMINANCE.................................. 14 l SPECIES DIVERSITY.................................. 14 I SIMILARITY AMONG STATIONS.......................... DISCUSSION--FAUNAL MONITORING...................... 16 18 QUANTITATIVE ALGAL COMMUNITY MONITORING................. 20 ALGAL COMMUNITY DESCRIPTIONS....................... 20 ALGAL COMMUNITY OVERLAP............................ 20 ALGAL BIOMASS...................................... 22 DISCUSSION--ALGAL MONITORING....................... 25
. QUALITATIVE TRANSECT SURVEYS............................ 27 EFFECTS PERSPECTIVE..................................... 31 I HIGHLIGHTS OF RESULTS.......................
QUANTITATIVE FAUNAL MONITORING.....................
........... 34 34 QUANTITATIVE ALGAL COMMUNITY MONITORING............ 34 QUALITATIVE TRANSECT SURVEYS....................... 35 LITERATURE CITEL'........................................ 36 I
I I I I
L TABLE OF CONTENTS (Continued) LIST OF TABLES Page Table 1. Algal Community Overlap in Percent Between Stations for the Period 1983-1988............ 21 Table 2. Summary of Impacts of PNPS on Benthic Communities.................................. 32 l LIST OF FIGURES Figure 1. Location of Rocky Point, Effluent, and Manomet Point Subtidal (10 ft. MLW) Stations. 5 Figure 2. Monthly PNPS Capacity Factor (Bars) and Circulating Pump Activity (Dotted Line) Plotted for the Period 1983 Through 1988..... 8 Figure 3. Species Richness for the Period April 1983 Through September 1988 Plotted with the Monthly PNPS Capacity Factor (MDC)........... 11 Figure 4. Faunal Densities (m ) for the Period April 1983 Through September 1988 Plotted with the i Monthly PNPS Capacity Factor................. 13 Figure 5. Shannon-Wiener Diversity (H') for Data j Excluding Mytilus edulis Plotted with the l Monthly PNPS Capacity Factor (MDC)........... 15 l Figure 6. Dendrograms Showing Results of Cluster Analysis of March and September 1988 Data Using Bray-Curtis and Group Average Sorting.. 17 Figure 7. Seasonal Fluctuations in Total'Mean Chondrus ! Biomass at the Manomet Point, Rocky Point, and Effluent Stations During Spring and Fall , Sampling Periods for the Collections Between ] April 1983 and September 1988 Plotted with l the Monthly PNPS Capacity Factor (MDC)....... 23 i Figure 8. Seasonal Fluctuations in Total Mean ) Phyllophora Biomass at the Manomet Point, Rocky Point, and Effluent Stations During Spring and Fall Sampling Periods for the Collections Between April 1983 and September 1988 Plotted with the Monthly PNPS Capacity Factor (MDC)................................. 24 ii
- 1. !
l TABLE OF CONTENTS (Continued) Figure 9. Seasonal Fluctuations in Total Mean Algal Biomass at the Manomet Point, Rocky Point, and Effluent Stations During Spring and Fall Sampling Periods for the Collections Between April 1983 and September 1988 Plotted with the Monthly PNPS Capacity Factor (MDC)....... 26 Figure 10. Area of Denuded and Stunted Zones in the vicinity of the PNPS Effluent Canal Plotted , with the Monthly PNPS Capacity Factor (MDC).. 28 Figure 11. Results of Qualitative Transect Surveys of the PNPS Acute Impact Zone off the Discharge Canal........................................ 30 LIST OF PLATES 1 l Plate 1. Effluent Flume Exiting the PNPS Cooling Water Discharge Canal.............................. 2 Plate 2. Diver with Underwater Writing Tablet Preparing to Enter Water..................... 6 4 l I I I I : I I I
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EXECUTIVE
SUMMARY
This volume of Semi-Annual Report No. 33 summarizes impact findings for the Pilgrim Nuclear Power Station (PNPS) benthic monitoring program from 1983 through 1988. Methods and procedures follow guidelines established by the Pilgrim Administrative Technical Committee (PATC) and adopted by Boston Edison Company (BECO) as modified in 1981. The PNPS cooling system has affected benthic communities at the mouth of the discharge canal by warming ambient waters and increasing current velocities sufficiently to cause benthic scouring, resulting in a denuded area immediately off the discharge canal and a region of stunted algal growth surrounding the denuded area. In 1988, particularly during April and May, the circulating water pump usage was low, resulting in little thermal loading and low discharge velocities. In 1988, in response to the prolonged PNPS outage that began in early March 1986 and persisted through the present reporting period, both the algal and f aunal communi ties at the Effluent station have recovered from scouring and thermal effects of the discharge. Recolonization by the red macroalga Chondrus crispus hac occurred in the formerly stunted and denuded areas of the acute impact zone. An increase in faunal species richness and densities has accompanied this increase in algal growth. By September, there was little difference in algal and faunal species composition between the Effluent and reference stations at Rocky Point, about 0.25 nautical miles northwest, and Manomet Point, about 2 nautical miles southeast I of the discharge. f } 4
INTRODUCTION Pilgrim Nuclear Power Station (PNPS) is a base-loaded, ; nuclear-powered electrical generating unit designed to produce 655 megawatts of energy under full operational conditions. Water withdrawn from Cape Cod Bay is used to remove heat from l the condensers. The cooling water returns to the Bay via a discharge canal designed to dissipate heat through rapid mixing and dilution. At full operational capacity, the two j circulating water pumps produce a combined flow of approximately 20 m3 per second. Plate 1 shows the plume j created as the effluent leaves the discharge canal. y.,7 I bl;$fq.. ~
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?S$%2k2~l~ "ff_W . ..% g f PLATE 1. EFFLUENT PLUME EXITING THE PNPS COOLING WATER DISCHARGE CANAL. THE EFFLUENT PLUME PRESENTS TWO SOURCES OF POTENTIAL IMPACT ON BENTHIC COMMUNITIES:
INCREASED TEMPERATURES AND INCREASED CURRENT VELOCITIES RESULTING IN BENTHIC SCOURING. The cooling system at PNPS may impact the benthic communities at the mouth of the discharge canal in two ways:(1) by warming 1 Ij Il )
the ambient waters' and (2) increasing current velocities sufficiently to cause benthic scouring. The modified benthic monitoring program being conducted j near PNPS began in' 1981. The program- objectives are to . 1 identify and assess the significance of impacts' associated with i PNPS operations on 'the nearshore benthic . communities. Introduction of an environmental stress has the' potential to affect benthic community members because of their limited ability to move away from disturbances. Significant changes in benthic community parameters may, therefore, be correlated with I the source of the disturbance. This volume of Semi-Annual Report Number 33 summarizes impact findings in relation to.the benthic monitoring program under Purchase Order No. 65218. It discusses overall data trends presented in volume 1 and in previous. reports (since 1983) to summarize the effects that PNPS operations have on benthic communities. l l }
METHODS The present' benthic moaitoring program uses quantitative and qualitative methods to detarmine the presence and magnitude of impacts associated with PNFS. Methods and procedures follow guidelines established by the Pilgrim Administrative Technical Committee (PATC) and adopted by BECO, as modified in 1981 (Boston Edison Co., 1987b). Methods are fully described Semi-Annual Report No. 29, Volume 1 (Boston Edison Co., 1987a). The quantitative studies measure and compare benthic community parameters at three stations (Figure 1): a surveillance station located nearly 120 m offshore from the mouth of the discharge canal (Effluent station), and two reference stations located 0.25 nautical miles northwest (Rocky Point station) and 2 nautical miles southeast (Manomet Point station) of the Effluent station. The latter site, because of its distance from the source of stress, is likely to experience a less severe efiect from PNPS than that experienced closer to the discharge canal, which is monitored by qualitative transect surveys. Data collected from the three stations are compared for spatial (reference vs. surveillance) and temporal (differences in seasonal trends and (nong years) variability. Differences between the Effluent and reference stations are then examined for indications of an impact from PNPS at the Effluent station. The acutely impacted area immediately offchore of the canal (0 to 90 m from the submerged ends of the canal) is monitored through qualitative diver Lurveys (Plate 2) to measure the extent of algal stunting ane: denudation caused by ) the thermal effluent. These observations cecu, on the red I macroalga Chondrus crispus, a species prevel.nt in western Cape Cod Bay and commercially harvested in the PNPS area. l Divers swim along a measured transect line, noting the boundaries of the denuded, stunted, and normal Chondrus zones of the acute impact area. Variations in zone size are recorded to determine the areal extent affected by PNPS operations. f i
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WITH THE PNPS EFFLUENT CANAL. 1 6
I BACKGROUND PNPS operationr1 conditions from 1983 to 1988 provide an I opportunity to assess (1) the degree of impact of the cooling water discharge to the benthic communities, and (2) the length of community recovery time if the effect of the discharge was I removed. capacity Figure 2 (MDC) factor and circulating water pump operation for presents the annual maximum dependable PNPS since 1983. The MDC is a measure of reactor output that approximates thermal loading to the marine environment. A. maximum MDC value of 100 percent represents the highest allowable change in ambient temperature (32'r oT). The mean from 1983 1988 was I approximately 30 capacity percent. factor During this to time, power output varied greatly. In 1983, PNPS was productive, with an annual MDC of 80.3 percent. The following year (1984) PNPS was off-line, yielding an annual MDC of only 0.1 percent. The 1984 outage resulted in reduced scouring in an area immediately off the discharge canal; partial circulating water flow occurred during most of the year and no flow occurred from late March to mid-August 1984. The extremely low MDC in 1984 was followed by a record high in 1985 (84.4 percent). The erratic pattern of I PNPS output continued in 1986, with an annual MDC of 17.5 percent. Outages began on March 7, 1986, and since mid-April 1986 the station has been completely off-line throughout the present reporting period. Two circulating water pumps operated through February 1986; only one pump was on-line from March 1986 through February 1987. Except for a few occasions, no circulating pumps were operating from mid-February through early September 1987. From September through December 1987 one pump was on-line. I During 1988, only one circulating water pump (either pump "A" or pump "B") was in operation at any one time (Marine Biocontrol Corporation, 1988). From January through June, a pump was operating, on a monthly basis, between 19 and 74 percent of the time; April and May were the lowest months. In I ,
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I I July, the operation of one pump increased to 97 percent, and, thereafter, one pump was operating 100 percent of the time. As a result of this low circulating water pump activity, negligible thermal loading and reduced current generation I l occurred at the Effluent station in 1988. Since 1983, the situation at PNPS has presented a valuable opportunity to compare the results from two peak operational years (1983 and 1985) with results from four years of potential environmental recovery (1984 and 1986 through 1988). The continuing PNPS outage that began in April 1986 was of particular interest during this reporting period. Because the outage lasted throughout 1988, benthic community recovery in response reduceC current and lack of thermal effluent I to the was expected to continue through 1988 and be more pronounced by the end of the year than at the end of 1987. The recovery response is similar to the responses noted in 1985 following the 1984 outage. These 1984/1985 responses were summarized in Semi-Annual Report No. 27 (Boston Edison Co., 1986) and included the following: I e A change in the relative rankings of the Effluent and reference stations in terms of I species richness; the Effluent station typically ranked third prior to the 1984 outage, but recovered to rank second by March 1985. e Species diversity values at the Effluent station that were more similar to diversity at the reference stations than would typically occur if PNPS were operating, e A lagged recovery of the effluent acute impact I zone, resulting in macroalgal growth within the previously denuded Chondrus zones. e Presence and absence of several species of algae I (most notably Gracilaria tikvahiae and Laminaria spp.) considered indicators of warm-water (G. tikvahiae) and cold-water (Laminaria spp.) I Eabitats, in response to the presence and absence of thermal effluent from PNPS. I I e
li l QUANTITATIVE FAUNAL COMMUNITY MONITORING SPECIES RICHNESS Uatil 1985, species richness (number of species present) at all three stations had varied seasonally, with low values in spring followed by high values in fall (Figure 3). In addition, the Effluent station showed depressed species richness when compared to the teference stations. Consistently lower species richness at the Effluent was assumed to be directly associated with PNPS thermal elevations. However, the Effluent station may be affected by circulating water pump activity and outside influences (i.e., weather). These activities could decrease algal cover and, therefore, habitat for the fauna, thereby increasing faunal vulnerability to storms. As discussed in Semi-Annual Report No. 27 (Boston Edison Co., 1986), 1985 Effluent data indicated a lagged response to the 1984 PNPS refueling outage. In 1986, species richness increased at the Effluent when no thermal effluent was discharged from PNPS. In 1987, species richness at all three stations increased from. March to September (rigure 3), with the Effluent having q the lowest number of species each sampling period. These I results, . observed during the continuing outage, resemble the observations made until 1985 when PNPS was operating. In 1987, the benthic community at the Effluent apparently still had not fully recovered from the effects of the thermal effluent i discharged until early spring 1986 (Boston Edison Co., 1988a). Statistically, in 1988, the stations showed minimal j differences in terms of number of species during either season. l In March 1988, species richness was lowest at the Effluent, yet a greater number of species were found than in March 1987. By September 1988, species richness at the Effluent had changed considerably, the number of species increasing to a level f similar to that found at the reference stations. Species richness at the reference stations has remained relatively 10
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h constant since September 1987, yet the values found at the Effluent station have risen steadily. This suggests that continuing recovery at the Effluent is making that station indistinguishable from the reference stations in terms of species richness. FAUNAL DENSITY Figure 4A shows total faunal densities (number of individuals per square meter) from 1983 through 1988 at all three stations. As reported in previous years, no seasonal pattern is apparent at any station. In addition, there is no consistent relationship between densities at any two stations. Generally, lower densities occur at the Effluent than at the reference stations, and the reference stations change in their relative ranking to each other. Occasionally, however, faunal densities at the Effluent are greater than at one or both reference stations. At all stations in 1988, much of the increase in faunal density was the result of the abundance of the blue mussel Mytilus edulis (Figure 4B). When Mytilus numbers were excluded from the data, the abundance of all other fauna (pooled data) also increased from spring to fall. This increase was most pronounced at the Effluent. The contribution of Mytilus (Figure 4B) to total faunal density at all stations has varied greatly throughout this monitoring program. Extremely high densities occurred in fall 1984 at all stations, in spring 1986 at the Effluent station, and during the spring and fall of 1988 at all stations. Except for these peaks, densities have been relatively low since i September 1985. - I The relationship between faunal density and Monthly j Capacity Factor (Figure 4A and 4B) indicates that variations in faunal density among stations are not directly related to PNPS operations. Total faunal densities at the Effluent station l 12
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IE . Sarrpling Period E Effluent Manomet Point Q Rocky Point --- Monthly PNPS Capacity Factor (%) l FIGURE 4. FAUNAL DENSITIES (m ) FOR THE PERIOD APRIL 1983 l THROUGH SEPTEMBER 1988 PLOTTED WITH THE MONTHLY PNPS l = CAPACITY FACTOR. A. TOTAL FAUNA, D. Mytilus edulis. 13
l during the two high-capacity years (1983 and 1985) differ in value and seasonal variation (sharp increase in 1983, slight decrease in 1985). In addition, total faunal density differs considerably during the two outage periods in 1984 and 1986-1988. The September 1988 data (Figure 4A) suggest the Effluent station is recovering as a response to the recent outage and, therefore, the reduction in scouring. The algal community has recolonized such that an acute impact zone was not detected during transect surveys. The fauna have recovered as a result of the provision of new habitat due to the increased algal growth. SPECIES DOMINANCE Fifteen faunal species have dominated (by generally >80 percent of total abundance; >90 in 1988) at all three stations throughout the program, regardless of season or year. Rankings of the top 15 dominants vary, but species composition has been fairly consistent at all stations. Therefore, faunal species dominance has not been noticeably affected by PNPS operations. In March and September 1988, Mytilus edulis was the most j abundant species, comprising 50 to 80 percent of the fauna at each station. Mytilus numbers increased considerably from March to September at the Effluent and Rocky Point. SPECIES DIVERSITY I Species diversity is a measure of the number of species i present (species richness) and their relative abundance in a 2 community. For consistency with previous reports, Mytilus edulis counts were excluded from the 1988 data calculations. i A seaconal pattern of low faunal diversity in spring followed by high diversity in fall has been observed at all f stations since 1983 (Figure 5). During spring and fall 1988, the Effluent continued to show lower diversity than the 14 f
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6 reference stations, however in September, the value was only slightly lower. SIMILARITY AMONG STATIONS The results of 1988 cluster analyses discussed in Volume 1 show that the faunal community (species composition) at the Effluent differed from the reference stations only in spring. In March, the replicates at each station clustered together into distinct station groups, yet similarity was greatest between the reference stations (Figure 6A). By fall, partly because of the abundance of Mytilus edulis, all stations were very similar (Figure 6B). Similarity was greater between replicates at different stations than replicates at the same station. Prior to 1988, the difference between stations was much more distinct. The increasing similarity between the Effluent and reference stations suggests benthic community recovery at' the Effluent station is related to the continuing PNPS outage.
-Seasonality in community structure was found at all !
stations in 1988. The effects, however, were muted due in part to the abundance of Mytilus. Similarity analyses of combined q spring and fall data indicated strong seasonal differences at l the Effluent station; the reference stations showed fewer seasonal differences. Results of additional 1988 faunal analyses indicate differences among stations and seasonal fluctuations can be I related to certain groups of species. Generally, the major differences between the fa'7al communities at the Effluent and j I reference stations were in the composition and density of l subdominant species, which play a marked role in influencing i q overall community structure, I i 16
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REPLICATE EF1 MP1 EF4MP5 EF5 MP4 RP3 RPS EF2 EF3 MP2 MP3 RP1 RP4 i FIGURE 6. DENDROGRAM SHOWING RESULTS OF CLUSTER ANALYSIS OF DATA USING BRAY-CURTIS SIMILARITY AND GROUP AVERAGE SORTING. A. MARCH 1988 DATA, B. SEPTEMBER 1988 j DATA. 17 _ _ _ - _ _ _ ._______ - __-_ - ________ - _____ ____- - - ~
DISCUSSION--FAUNAL MONITORING The. results. of 1988 faunal community analyses indicate that, by the end of the sampling year, only minor differences existed between the Effluent station and the reference stations. Species richness remained lower at the Effluent station than at the reference stations, but the similarity analysis showed that similarity between the Effluent and reference stations was high. Species richness has increased steadily at the Effluent station since March 1987, but values at the reference stations have remained about the same since September 1987. Differences in faunal densities among stations do not appear to be related to PNPS operations. In addition, the species that comprise the majority (generally >80 percent) of the total fauna at all stations differ only in relative rank. Seasonal trends in faunal diversity co-vary at the three stations and in the past have indicated depressed diversity at the Effluent compared with the reference stations. Logan and Maurer (1975) have hypothesized that faunal communities in the mouths of thermal effluent canals are in a "noninteractive, pioneer state," characterized by high diversity, low species numbers, and low population densities ~,I caused by sporadic and severe environmental changes, such as variations in temperature or turbidity. Results of the benthic monitoring program at PNPS have indicated that faunal communities at the Effluent station are somewhat different from those described by Logan and Maurer, possibly because the station is not located in the mouth of the discharge canal. Although species richness is typically depressed at the J j Effluent station, diversity is also depressed and faunal density is not always the lowest of the three stations. The i Effluent community is one that is believed to be characteristic j of a stressed environment. l Logan and Maurer (1975) state that the occurrence of high diversity in the path of a thermal effluent is probably caused l by recolonization following sporadic periods of severe l 18
ll i l I environmental change (i.e., decreased temperatures caused by storms, extreme tides, or plant shutdown). Data from the benthic monitoring study, therefore, suggest that although I there station, has been an conditions effect of PNPS discharge at the Effluent at the station were relatively stable for prolonged periods of time, resulting in sustained low diversity I compared with the reference stations. This stability was maintained until 1984, when PNPS experienced a long shutdown. Under " normal" PNPS operating conditions, the faunal communities at the Effluent station experience different annual temperature variations than are experienced at the reference stations (i.e., higher temperatures in the summer and winter due to thermal loading); resulting in the seasonal differences I in the community parameters discussed earlier. These annual variations were compounded by the extreme maxima and minima of PNPS operation from 1983 through 1986, creating environmental variability at the Effluent station on a different scale than would be expected under continuous operation. As has been noted (Boston Edison Co., 1987b), the impact of PNPS at the Effluent station is on the rarer, more transitional species rather than on the dominant species. Although the effect of PNPS at the Effluent station is not I extreme under normal conditions, erratic PNPS operation between 1983 and 1986 created prolonged thermal variations from high power output (maximum impact) followed by no power output (maximum recovery) and variations in discharge current flow from full flow (maximum impact) to no flow (minimum impact). Those fluctuations resulted in environmental impacts at the Effluent station that were less consistent than those seen before 1984, explaining variations in the relative ranking of the stations for several of the parameters measured during this I program. relatively Comparisons of faunal communities during stable pre-1984 operational phase with the variable the communities during the 1984 to 1986 erratic operations and the increasing community similarity among all stations since the beginning of the long outage in nid-1986 allows for enlightened 19 1
L assessments of future effects under a wide variety of discharge L conditions. QUANTITATIVE ALGAL COMMUNITY MONITORING ALGAL COMMUNITY DESCRIPTIONS The algal community at the Effluent station is dominated, by the red algae, Chondrus crispus and Phyllophora spp., species that also dominate the reference stations. However, one indication of- the effect of PNPS on the Effluent station algal community, unlike the faunal community, has been the presence of several less abundant species that are absent from the _ reference stations. The most significant of these is the red macroalga Gracilaria tikvahiae. Gracilaria' tikvahiae, considered- an indicator of warm-water habitats (Boston Edison Co., 1982), was not_found in 1988 samples or observed during the qualitative transect surveys off the discharge canal. This species occurred regularly at the Effluent station during normal operational years when a thermal effluent was discharged. In 1986, a
-drastic decrease of G. tikvahiae was observed, and the q disappearance of this species _since 1987 was clearly related to the continuing PNPS outage (lack of thermal effluent). A similar decrease in abundance at the Effluent occurred in . response to the 1984 outage (Boston Edison Co., 1986).
1 ALGAL COMMUNITY OVERLAP
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Table 1 presents algal community overlap values between stations (i.e., the number of species shared by a given pair of stations) since 1983. The tendency has been for the two ( reference stations to be more similar to each other (higher i overlap vclues) than to the Effluent station. l In 1988, as during 1983-1987 (Table 1), the overlap values for the various station pairs (Manomet Point vs. Rocky 20
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! Point, Manomet Point vs. Effluent, and Rocky Point vs. Effluent) were not very different, indicating a relatively uniform algal species distribution among all stations. In March, the . reference stations were more similar (greater overlap) in species composition to each other than either reference station was to the Effluent station (Boston Edison Co., 1988b). However, in September both reference stations were more similar to the Effluent station than to each other. This suggests that all stations are becoming similar in terms of species composition. Overall, the similarity among all three str.tions was high: 381 percent in spring and >82 percent in fall. As suggested last year (Boston Edison Co., 1987b), these species overlap variations are not only . influer;ced by PNPS operations, but are also part of naturally occurring, long-term variations in Cape Cod Bay. Moreover, the continuation of the outage for almost three years did not cause any marked changes in the dominant algal species composition, indicating that effects of PNPS operations on species composition are minimal. ALGAL BIOMASS I In general, 1988 algal biomass followed the same seasonal i pattern seen since 1983 (except for 1986). Sharp increases in Chondrus crispus biomass at all stations, especially at the i Effluent, were seen from March to September (Figure 7). The increase in Chondrus biomass at the Effluent was the largest , i spring-to-fall increase at any station since April 1983. In contrast to the increase i 'n Chondrus biomass from spring to fall, Phyllophora spp. biomass decreased at the d Effluent and Manomet Point stations, and showed only a slight increase at Rocky Point (Figure 8). The decrease at Manomet Point has continued since fall 1985 and, by September 1988, mean biomass at Manomet Point was at its lowest since April 1983. 22
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l l a The increase in Chondrus biomass from March to September 1988 resulted in generally higher total algal biomass over the study area (Figure 9). The Chondrus increase, especially at the Effluent ' station, was sufficient to result in a higher total algal biomass than measured in September 1987. DISCUSSION--ALGAL MONITORING The results of algal community monitoring carried out in 1988 support the conclusions drawn from the faunal studies' results. Because of the continuing PNPS outage and concomitant lack of a thermal effluent, the Effluent station appears to be recovering. In March, similarity measurements (Jaccard's coefficient of community) indicated a slightly greater degree of similarity between the reference stations than shown by a comparison of the reference stations with the Effluent station. In September, however, both reference stations were more similar to the Effluent than to each other, indicating all three stations are becomino similar. , During this program, the algal community at the Effluent station has experienced disturbances affecting species composition rather than overall abundance (biomass). Biomass values for the major algal categories fail to show any patterns, either among stations or over time, that would indicate a significant effect of PNPS at the Effluent (Figures 7 to 9). The impact of PNPS on the Effluent algal community is reflected in the presence or absence of several less dominant species. For example, the continuing outage accounts for the j absence since 1987 of Gracilaria tikvahiae, a warm-water species. This impact suggests that there are more opportunities available for new species to colonize the Effluent rather than the reference stations. The variation in less dominant species is considered less severe than might be expected if the Effluent station were closer to the areas of acute. impact (i.e., near the mouth of the discharge canal). 25
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E l B i QUALITATIVE TRANSECT SURVEYS l A lagged recovery response to the 1984 PNPS outage within l j i the acute impact zone was reported in Semi-Annual Report No. 27 (Boston Edison Co., 1986). Evidence of this lagged recovery
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included a decrease that began in mid-1984 and continued through mid-1985 in the size of the total impact area. Figure 10 presents results of the qualitative transect surveys from 1983-1988. The total acute impact area is plotted with the extent of the denuded zone and the monthly MDC factor. The stunted zone is represented by the difference between the denuded and total acute impact zones. Between December 1984 and December 1985 the total impacted area (denuded and stunted I zones combined) was the smallest recorded since 1983, indicating a lagged recovery of this area in response to the lack of thermal effluent in 1984. This phenomenon reversed itself under normal PNPS operating conditions, and between September and December 1985 showed a lagged increase of the acute impact zone size. These results confirmed a lagged period of about six to nine months between the causal factor (cessation or resumption of thermal effluent discharge) and associated response (decrease or increase of the acute impact I zone size). Since 1987, increased recolonization of the denuded and stunted zones by Chondrus crispus has made zone boundaries difficult to distinguish (no measurements could be made after June 1987). As in summer 1984, the considerable decrease of the denuded area of the acute impact zone from December 1986 to June 1987 was mostly the result of the shutdown of the circulating water pumps from mid-February to early September (Boston Edison Co., 1988a). Apparently, water current scouring I is a greater stress to algal colonization than increased water Scouring denudes the substratum, whereas temperature. temperature results in stunted growth. The increase of the denuded area of the acute impact zone in September and December E 27
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l lI 1987 can be related to the resumption of circulating water pump operation in September, confirming this assumption. I In 1988, the circulating water pump activity was low, resulting in little thermal loading and discharge current. Results of the 1988 transect survey (Figure 11) showed increased recolonization of the formerly denuded and stunted 3 zones by Chondrus in response to the continuing outage. Divers were unable to detect boundaries of these zones and no areal measurements could be made. During the 1987 qualitative transect surveys, Laminaria spp., an indicator of cold-water habitats, was observed in the acute impact zone and cited as an indication of recovery of the I area during the power outage. In 1988, the continued presence of Laminaria spp. in the acute impact zone remains an important indicator of the lack of a thermal component of the discharge. I I E I I E I I I g 29
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( lI l l i l EFFECTS PERSPECTIVE I E An overview of benthic community response to PNPS l operations between 1983 and 1988 is presented in Table 2. The power outage that began in early March 1986 has continued through the 1988 report period, resulting in a lagged recovery of benthic communities at the Effluent station off the mouth of the discharge canal. During 1987, the recovery was most obvious in the macroalgal assemblages of the acute impact zone, the zone that included an area completely denuded by the scouring effect of the discharge, and an area of algal growth stunted by the thermal component of the discharge. I In 1988, the faunal and macroalgal assemblages continued to recover at the Effluent station. Recolonization by Chondrus crispus occurred to the point where the stunted and denuded zones could no longer be distinguished from the surrounding typical growth areas. An increase in faunal species richness and densities accompanied the increased macroalgal coverage. The recovery in the acute impact zone is the response most directly related to PNPS operations. Overall, the full impact potential of PNPS has not yet been observed because the mean operating rate of the plant has been only about 46 percent to I date. I I E I I I 31
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7 HIGHLIGHTS OF RESULTS i 1 QUANTITATIVE FAUNAL MONITORING
- 1. Species richness, lowest at the Effluent station in March, increased to levels seen at the reference stations by September. This indicates that, as a result of the continuing power outage, the Effluent station is becoming similar, in terms of species composition, to the reference stations.
- 2. Faunal densities were lowest at the Effluent station in March but highest in September. Densities increased dramatically at all stations throughout the year. Results .
from 1983 through 1988 do not indicate a direct relationship between PNPS operations and faunal densities.
- 3. Species composition of the top 15 dominants has been similar at all stations and fairly consistent since 1983.
Dominant species were not measurably affected by PNPS and showed no response to the prolonged outage in 1988. In March and September Mytilus edulis was numerically dominant at all stations, comprising more than half the fauna.
- 4. Species diversity has typically been lowest at the Effluent station since 1983. The continuation of this trend in 1988 may be indicative of the time required for !
full recovery of faunal communities.
- 5. Similarity was high between the reference stations in z March 1988, and by September all stations were similar, '
i due partly to the abundance of Mytilus edulis. From 1983 to 1986, similarity between the reference stations was much higher than between the Effluent and reference stations. The partial recovery of the Effluent fauna indicated by the similarity measure in 1988 may be a response to the continuing outage at PNPS. QUANTITATIVE ALGAL COMMUNITY MONITORING
- 1. Algal communities were similar among all stations in 1988. !'
No warm-water algae were found at the Effluent station. During normal operational years, Gracilaria tikvahiae was regularly observed. However, this species has been absent ! since 1987 (after a decline in 1986) because of a lack of 2 thermal effluent from PNPS.
- 2. From 1983 to 1987, the number of algal species shared (overlap) between the reference stations was slightly higher than between the Effluent and reference stations. ,
In fall 1988, due to recolonization at the Effluent 34
l I station as a result of the prolonged outage, algal I 3. assemblages at the reference stations were more similar to the Effluent station assemblages than to each other. Algal biomass generally showed the same seasonal pattern observed since 1983 (except for 1986); biomass was low in spring and high in fall. However, since 1987, the Manomet Point station has shown greater biomass in spring than in I fall. Of all stations, the Effluent station had the lowest biomass in spring and highest biomass in fall. QUALITATIVE TRANSECT SURVEYS The size of the denuded area of the acute impact zone is mainly influenced by the circulating water pump operation. I In algal 1988, circulating water pump activity was low, resulting in little current generation. Recovery of the community occurred in 1988. Extensive recolonization of Chondrus crispus during the prolonged I outage resulted in a disappearance of the formerly stunted and 'enuded zones; clear boundaries were not detected. I I I E I I I I I I
"s E l
LITERATURE CITED Boston Edison Co. 1982. Marine ecology studies related to operation of Pilgr'.m Station. Semi-Annual Report No. 19. Boston, MA. Boston Edison 'Co. 1986. Marine ecology. studies related to operation of Pilgrim Station. Semi-Annual' Report No. 27. Boston, MA. Boston . Edison Co. 1987a. Marine ecology studies related to-operation of Pilgrim Station. Semi-Annual Report No. .9. 2 Boston, MA. LBoston Edison Co. 1987b. Marine ecology studies related to operation of Pilgrim' Station. Semi-Annual Report No. 30. Boston, MA. Boston Edison. Co. 1988a. Marine ecology studies related to operation of. Pilgrim Station. Semi-Annual Report No.'31. Boston,1MA. Boston Edison Co. 1988b. Marine ecology studies related to operation of Jilgrim Station. Semi-Annual Report No. 32. Boston, MA. Logan, D.T. and D. Maurer. 1975. Diversity of marine invertebrates .in a thermal effluent. J. Water Poll. Con. Fed. 47(3):515-523. q Marine Biocontrol Corporation. 1988. Pilgrim Station Chlorine and Biofouling Monitoring Program, Monthly Status Report, December 1988, submitted to' Boston Edison. Boston, MA. f 4
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I ICH1HYOPLANKTON ENTRAINMENT MDN]TORING AT PILGRIM NUCLEAR POWER STATION JANUARY - DECEMBER 1988 Volume 1 of 2 (Results) I I Submitted to .l 5 Boston Ecison Company Boston, Massachusetts DY Marine Research, Inc. falmouth, Massachusetts I March 8, 1989 Revised , April 3, 1989 I ; I I I --_-
~
I l I 1ABLE OF CONTENTS SECTION PAGE I EXECUTIVE
SUMMARY
l 11 INTRODUCTION 2
!!! METHODS AND MATERIALS 3 IV RESULTS AND DI CUSS 10N A. Ichthyoplankton Entrained - 1988 /
B. Multi-year !chthyoplankton Comparisons 14 C. Lobster Larvae Entrained 29 V HIGHLIGHTS 30 I APPENDICES A and B (available upon request) I I I I I g 1
r .-
,s LIST OF FIGURES FIGURE PAGE 1 Entrainment sampling station in PNPS discharge canal. 4 2 Location of entrainment contingency plan sampling stations, C-1 through C-13. 6 3 .Mean monthly densities per 100 m 8 of water in the PNPS discharge canal for the eight numerically dominant egg
-species and total eggs, 1988 (dashed line). Solid lines encompassing shaded area show high and low values over the 1975-1987 period. 21 4 Mean monthly-densities per 100 m 8 'of water in the PNPS discharge canal for the ten numerically dominant larval species and total larvae, 1987 (dashed line). Solid lines encompascina shaded area show high and low valuer over the 1975-1987 period. 25 LISl 0F 1 ABLES TABLE ffASL Species of fish eggs (E) and larvae (L) obtained in
~
1
-ichthyoplankton collections from the Pilgrim Nuclear Power Station discharge canal, January-December 1988. 8 2 Species of fish eggs (El and larvae (L) collected in the PNPS discharge canal, 1975-1988. 15 LIST OF APPENDICES .
APPENDIX I 4* Densities of fish eggs and larvae per 100 m8 of water recorded in the PNPS discharge canal by species, date, and replicate, January-December 1988. ! I B+ Mean monthly densities and range per 100 m8 of water for the dominant species of fish eggs and larvae entrained at PNPS, January-December 1975-1988.
*Available upon request.
ii
I ! 1 dEU110N 1 i I EXECUTIVE
SUMMARY
ichtnyoplankton sampling with one circulating seawater pump operating was completed twice per montn in January, February, Oc t o b e r-lie c emo e r , and weekly from March - September. Numerical dominants among the 41 species represented in the 1988 collections includea sculpins, rock gunnel, seasnails, sana lance, winter flounder, Atlantic mackerel, labrics, fourbeard rockling, hake, and windowpane. Comparisons between 1988 monthly mean densities, per 100 m 8 of water, and those recorded over the 1975-1987 period suggest that Atlantic coa and American plaice eggs were uncommon in 1988. Record high numbers were recorded ior Parallenthys-Stopntnalmus and mackerel eggs as well as rock gunnel, seasnail, and sculpin Jarvae. No larval lobsters were obtained in 1968, the previous one being recorded in 1982. I I lI I
- I l
1
bell 10N 11 INTRODUCTION Ibis report sus.aarizes results of ichthyoplankton entrainment sampling l conducted at the Pilgrim Nuclear Power Station (PNPS) aisenarge canal on a l regular basis f rom January through l'ecember 1988. Work was carried out by l Marine Research, Inc. (MRI) for Boston Edison Company (BECo) under Purcnase ( Order No. 65221 in compliance with environmental monitorinQ and reporting requirements of the PNPS NPDES permit (U.S. Environmental Protection Agency 1 I and Massachusetts lJi vi si on of Water Pollution Control). In an effort to condense the volume of material presented in these reports, details of Interest to some readers may have been omitted. Any questions or requests for additional information may be directed to Marine Research, Inc., Falmouth, Massachusetts, through BECo. I I I I I 2 I
l SECTION lil ME1 HODS AND MATERIALS Entrainment sampling at PNPS was completed twice per month during January, February, October, November, December, and weekly March- beptember. Samples were coll'ected in triplicate f' om r rigging mounted approximately 30 meters- from the headwall of the disenarge canal (Figure 1) at low tide during daylight hours. A 0.333-mm mesh, 60-cm diameter plankton net affixed to this rigging was streamed in the canal for B to 12 minutes depending on the abundance of plankton and detritus. In each case, a minimum.of 100 m? of water was sampled. Exact filtration volumes were calculated using a General Oceanics Model 2030R digital flowmeter mounted in the mouth of the net. Although PNPS was out of service during 1988 and there were times when no ciculating water system (CWS) pumps were in operation, one was operating during each ichthyoplankton collection period. All samples were preserved in 107. Formalin seawater solutions ana l returned- to the laboratory f or microscopic analysis. A detailed description of the analytical procedures may be found in MRI (1988)*. When the Cape Cod Bay ichthyoplankton study.was completed in 1976, a contingency sampling plan was added to the entratnment monitoring program. l This plan was designed to be implemented if eggs or larvae of any dominant 1,
- Marine Research, Inc. 1988. Ichthyoplankton Entrainment Monitoring at Pilgrim Nuclear Power Station January-December 1987. Ill.C.1-6-10. In:
Marine Ecology Studies Related to Operation of Pilgrim Station. Semi-Annual , Report No. 31. Boston Edison Company. 3
CAPE COD BAY ih. h.
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species proved to be " unusually abundant" in the PNPS discharge samples. lhe goal of this sampling plan was to determine whether circumstances in the vicinity of Rocky Point, attributable to PNPS operation, were causing an abnormally large percentage of ichthyoplankton populations there to be entrained or, alternatively, whether high entrainment levels simply were a reflection of unusually high population levels in Cape Cod Bay. " Unusually abundant" was defined as any mean density, calculated over three replicates, which was found to be 50% greater than the highest mean density observed during the same month from 1975 through 1987. lhe contingency sampling plan consists of taking additional sets of triplicates from.the PNPS discharge on subsequent dates to monitor the temporal extent of the unusual censity. An optional offshore saepling regime was also established to study the spatial distribution of the species in question. 1he offshore contingency program consists of single, oblique tows at each of 13 stations (Figure 2) on both rising and falling tides for a total of 26 samples. Any contingency sampling requires authorization from Boston Edison Company, i f i 5
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SEC110N IV RESULTS AND DISCUSSION A. Ichthyoplankton Entrained - 1988 Population densities per 100 8m of water for each species listed by date, . station, and replicate are presented f or 1988 in Appendix A. (available upon. request). lable 1 lists all species represented in the 1988 collecti",ns,.ind'icates.the months eggs and/or larvae of each species were found, and for the more common' species the months of peak abundance. Ichthyoplankton collections are ' summarized below within the three . primary spawning seasons observed in Cape Cod bays wanter-early spring, late spring-early summer, and late summer-autumn. Winter-early sprino spawners tDecember-April) Although sampling occurs at the end of the calendar year, December
~
represents the beginning of the winter-early spring spawning season. In December 1988 collections were very light with only two species being represented in the catch. Atlantic cod (Gadus morhua) was represented by one' egg and Atlantic herring (Clupea harenaus harenaus) was represented by one larva. Four species were represented in the January collections, ten were represented in February, 16 in March, and 17 in April. Samples taken during these four months contained l I relatively few eggs'since species contributing the greatest numbers to i entrainment during this period spawn demersal, adhesive eggs which are
- h. not normally subject to entrainment. Only two eggs were found during i
January and February combined, one an unidentified demersal, the other ! l American plaice (Hippoglossoices platessoides). March samples contained a greater variety of eggs (b species) with wanter flounder 7
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(Pseudopleuronectes americanus) being numerically dominant. They accounted for 92% of the month's total with a mean density of 9 eggs per 100 m8 of water. Fourbeard rockling (Enchelyoous cimorluss, Atlantic cod, American plaice, and yellowtail flounder (Limanda ferrucinea), all with mean monthly densities less tnan 1 per 100 m 8, completed the March egg catch. April collections contained six species j of eggs with plaice and rockling being most numerous; monthly mean densities per 100 m3 of 3.7 and 3.3 accounted for 26 and 24% of the total, respectively. Atlantic cod, haddock (Melanogrammus aeglefinus), yellowtail, and winter flounder completed the catch. Since winter flounder eggs are demersal and adhesive, their densities in tne PNPS discharge canal cannot be considered representative of densities in the waters around Rocky Point. Those which were collected f rom the discharge canal were probably dislodged from the bottom by currents or pernaps fish.
. Larval collections during the winter-early spring period contained increasing numbers of species with each successive month - 4 in January, 9 in February, 13 in March, and 14 in April. Numerical dominants incluced sculpin (Muorocephalus spp.J, rock gunnel (PholIs cunnellus), seasnails (Ll o ari s spp. ), and sand lance (Ammodvtes sp.).
Sculpin densities averaged 0.4 in January (37% of the total larval catch), 41 in February (82% of total), lit in March (48%), and 43 per 100 m 8 in April (43%), with the grubby (M. aenaeus) Deing most j ) For rock gunnel aDundant overall among the three sculpin species. densities per 100 me of water were 0.5 in January (50% of total), 8 in February (16%), 118 in March (50%), and 4 in April (5%). Larval seasnails were uncommon until April when a monthly mean of 17 larvae l 11
/ l '.' ) .', per 100 m8'was recorded representing 25% of the larval catch; the majority of these (99.4%) were J., atlanticus. Larval sand, lance.dtd not appear in the January collections, averaged 0.4 per 100 m8 In tne-February collections (1% of the catch), 2 per 100 m8 in March (1%), and 11 per 100 m8 in April (16%). Late spring-early summer (May-July) Overall 19 species were represented in May, 20 were represented in June, and'19 were represented in July, witn 9, 13, and 11 species being represented by eggs, respectively. Numerically dominant eggs included Atlantic mackerel (Scomber scombrus) and the labrids. Mackerel accounted for 87% of the eggs taken in May and 61% of those taken in June; they declined sharply after that contributing only 1% to the July total. Monthly mean densities for mackerel eggs were 1724 per 100 m a in May, 2220 in June, and 7 in July. Combined with the labric-Limanda group, labridae eggs accounted f or an additional o% of the eggs in May and 35% in June; by July these eggs accounted for 91% of the total. Monthly mean densities amounted to 116 labrid eggs per 100 m 8 in May, 1265 per 100 m8 in June, and 731 per 100 m 8 in July. Larval collections contained 13 species in May, 15 in June, and 14 i in July with seasnails (only ,L: atlanticus were found during this 1 period), winter flounder, Atlantic mackerel, ar.d cunner (lautogolabrus j
-. ]
adspersus) being the numerical dominants. Seasnails represented 42% of. the larvae taken in May with a monthly mean density of 28 per 100 m8 of water, and 35% of the larvae in June with a monthly mean of 7 per 100-s m; they were absent in July. Winter flounder added 35% to the May catch with a monthly mean of 24 per 100 m8 and 3% to the June catch 1 with a mean of 1 per 100 m8 Larval flounder were absent in July, 12
Atlantic mack'erel were only found in June when:a monthly mean density. of '6 per 100 58 accounted.for 29% of the total larval catch. Cunner were absent in May but contributed 5% and 44% to the catch in June and July, respectively; corresponding monthly mean densities were 1 ane 7.
' Atlantic. menhaden'(Brevoortia tyrannus), tautog (Tautoga onitts), and fourbeard- rockling were also relatively important in the July. catch.
They contributed 17, 14, and 12% to the total kith monthly .mean densities of 3, 2, and 2, respectively. Latt summer-autumn spawners (August Novemoer) 1he number of species represented each month typically declines steadily through this period. In 1988,.16 rpecies were represented In August, 10' were represented in September, 7 in October, and none were taken in November.- Ten,'seven, and si'r sp2cies were represented by eggs, respectively. Egg collections were dominated by the labrids, rockling, hake (Urcohvets spp.), and Hindorpare (Scophthalmus aquosus). Combined with the labrid-Licanda group, labridae eggs accounted for 43, 9, and 2% of the total in August, September, and October, respectively. l The Enchelycpus-Urophycis-Peprilus group togetter with late-stage reckling and hake eggs contributed an additional 53% in August, 17% in September, and 74% in October. Windowpane, assuming they dominated the Paralichthys-Scochthalmus grouping, added 17% to the egg tctal in August, 71% to the total in September, and 7% to the total in October, j I l Mor,thly mean densities per 100 8m of water for the labrids amounted to 54 -in August, declining to 4 in September and 0.1 in October. Windowpane had mean densities of 21, 31, and 0.2 per 100 am curing the three respective months. l l 13
,u i
f Larval collections contained 13, 8, and 3 Epecies during Huqust. September, and October, respectively. Numerical dominants were the same as among the eggs, ie., cunner, rockling, hake, and windowpane. Cunner contributed 28 and 1% of the larvae in August and SeptemDer with monthly mean densities of 4 and 0.1 per 100 m 8 , respectively; they were absent in October. Rockling added 42% to the August total, 73% to the September total, and 71% to the October total; monthly mean densities were 6, 4, and 1 per 100 m', respectively. Hake and windowpane contributed 4 and 3% to the larvai tota! in August with monthly mean densities of 0.6 and'0.4 per 100 ms, 9 and 7% to the September total with mon tt. l y means 04 0.6 and 0.4 per 100 m 8, and 0 and 21% to the October total with means of 0 and 0.3 per 100 m 8, respectively. B. MJlti-VeBr lchthyoplankton Comparisons Tab'.e 2 presents a mester species list for ichthyoplankton ecliected from the discharge canol at PNPS and indicates the years each spec:es was taken'frem 1975 through 1988. The general period of occurrence within the year is also indicated for each species including the peak period for the numerical dominants. A total of 41 species was represented in the 1988 collections compared with an average of 38 over the 19'/b-1987 period. No new species were added to the list in 1908. Monthly.mean densities per 100 m 8 of water were calculated for each of ] l the numerically dominant fish eggs, those accounting for 99% of the 1988 egg total, as well as total eggs (all species combinea) for each year from 1975 j through 1888 (Apptidix B, available upon request). To help compare values over the 14-year period, egg data were plotted in Figure 3. For this figure ccd and pollock (Pollachius virens; eggs were combinea with the gadid-Glyptocephalus group, rockling anc hake were comtined with the 14
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