BECO-87-034, Marine Ecology Studies Semiannual Rept 29 for 1986. W/
| ML20210A979 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 12/31/1986 |
| From: | Richard Anderson, Bird R BOSTON EDISON CO. |
| To: | MASSACHUSETTS, COMMONWEALTH OF |
| References | |
| 29, BECO-87-034, BECO-87-34, NUDOCS 8705050205 | |
| Download: ML20210A979 (420) | |
Text
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BOSTON EDISON COMPANY REGULATORY AFFAIRS AND PROGRAMS
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MARINEEC0LOGYSTUDIES RELATEDTOOPERATION0FPILGRINSTATION SENI-ANNUALREPORTN0.29 REPORTPERIOD: JANUARY 1986THROUGHDECEMBER1986 DATEOFISSUE: APRIL 30,1987 Compiled and Reviewed by: M n r Mar F eries Biologist i I l Bo NEn d sS c p [' 25 Braintree Hill Office Park Braintree, Massachusetts 02184
TABLE OF CONTENTS SECTION I
SUMMARY
II INTRODUCTION III MARINE BIOTA STUDIES IIIA Marine Fisheries Monitoring and Impact IIIA.1 Annual Report on Monitoring to Assess Impact of the Pilgrim Nuclear Power Station on the Marine Fisheries Resources of Western Cape Cod Bay, January - December 1985 (Characteriza-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 Fisheries Resources of Western Cape Cod Bay, January - December 1986 (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 1986 (Characterization of Benthic Communities) - (Battelle New England Research Lab) IIIB.2 Benthic Algal and Faunal Monitoring at the Pilgrim Nuclear Power Station, January - December 1986 (Impact on Benthic Communities) - (Battelle New England Research Lab) IIIC Plankton Monitoring and Impact IIIC.1 Ichthyoplankton Entrainment Monitoring at Pilgrim Nuclear l Power Station, January - December 1986 (Results) - (Marine l Research, Inc.) IIIC.2 Ichthyoplankton Entrainment Monitorin'g at Pilgrim Nuclear l Power Station, January - December 1986 (Impact Perspective)
- (Marine Research, Inc.)
IIID Impingement Monitoring and Impact l Impingement of Organisms at Pilgrim Nuclear Power Station: January ) - December 1986. (Boston Edison Company) l
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IV FISH SURVEILLANCE ! 1 IVA Overflights Summary Report: Fish Spotting Overflights in Western Cape Cod Bay in 1986. (Boston Edison Company) V Minutes of Meeting 66 of the Administrative-Technical Committee, Pilgrim Nuclear Power Station 11
SUMMARY
Highlights of the Environmental Surveillance and Monitoring Program re- .sults obtained over this reporting period (January - December 1986) are presented below (Note: Pilgrim Station was in an outage from early April through December 1986, so data reflects a control situation for most of the year, with no thermal influence on aquatic resources): Marine Fisheries Monitoring:
- 1. In the April-November 1986 shorefront sportfish survey at
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Pilgrim Station, an estimated 2,000 angler visits accounted for 500 fishes caught. Cunner (48%), winter flounder (32%) and bluefish (11%) dominated the sportfish catch. The lack of a thermal component during the 1986 Pilgrim outage resulted in a much reduced sportfishery success rate.
- 2. Pelagic fish mean CPUE (Catch Per Unit Effort) for 1986 at the gill net station (99.6 fishes / set) decreased 16% from 1985 when 118.8 fishes / set were taken. Pollock (51%), cunner (16%) and Atlantic herring (8%) were 75% of the total catch. Pollock and cunner catch rates were similar from 1985 to 1986 while At-lantic herring increased substantially. A significant positive correlation was found for cunner catch and Pilgrim Station op-erational output (thermal loading to the environment) for 1973-1983, 1985. A general attraction to the thermal discharge l appe'rs a to exist for the more abundant species categories.
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- 3. Shrimp trawl catch for 1986 recorded 31, benthic fish species i with little skate -(34%), winter flounder (32%) and windowpane
' (16%) composing 82% of the total. Mean CPUE for all species j was -23.4 at the discharge surveillance station, 39.2 (highest) at the intake surveillance station and 28.5 (two more than in 1985)- for all - stations pooled in 1986. The presence of sub-i I
stantially larger numbers of small winter flounder and win-dowpane caught in the intake embayment, compared to the other stations, suggests its attraction as a possible nursery area. 1 Winter flounder abundance, in spring and summer,-at the intake surveillance station was significantly greater than at the dis- ! charge and reference stations. A positive correlation between , catch abundance and Pilgrim thermal loading to the marine en-4 j vironment was found for winter flounder, windowpane and yellow- , l 4 tall flounder. ] i 1 1 j 4. Adult lobster mean monthly catch rate per- pot haul, in May - November 1986, was 0.77 lobsters which is 17% greater than the 1985 rate (0.66). The surveillance area (thermal plume) catch rate was 0.40 while the reference area (control) was 0.41. The seasonal, legaf lobster catch rate since 1970 i has not been significantly lower in the thermal plume area than l 3 in control areas. A significant negative correlation was noted ' l between legal lobster catch for thermal plume areas and mean j annual Pilgrim Station output for the period- from 1973 - 1983, 1 1985. l l-I-2 l
- 5. In May -
October 1986 fish observational dive surveys, 8 species were observed in the thermal plume area. Cunner (80%), tautog (11%), and pollock (8%) were the most numerous species seen, the first two being most abundant in the direct path of the Pilgrim discharge current. Total number of fishes observed increased 36% from 1985. Most fishes were in greatest concen- trations at stations in the denuded zone (64%), followed by the control zone (31%) and the stunted zone (5%). This represents a change from 1984 (also an outage year, but with a minimal discharge current) when most fish were observed in the control zone, out of the direct path of the Pilgrim l Station effluent.
- 6. Atlantic silverside accounted for 39% of the 1986 haui seine (shore zone) fish catch with a total of 26 species collected.
Shrimp (Crangon spp.), green crabs (Carcinus maenus) and ctenophores were abundant in the invertebrate catch. Fish cap-tured in the PNPS intake embayment (first in CPUE) were dom-Inated by blueback herring and sand lance spp., and included { Atlantic menhaden, winter flounder and rainbow smelt among the more numerous species. A deeper seine net (10' compared to 6'), to more effectively sample the intake, was utilized begin-ning in 1984 and results in 1986 Indicate this area is more similar in fish fauna to an estuary than exposed coastal areas. Impingement Monitoring:
- 1. The mean January - December 1986 Impingement collection rate was 1.26 fish /hr. The rate ranged from 0.10 fish /hr (January)
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t to 3.00 fish /hr (August) with Atlantic herring comprising 33.9% of the catch, followed by rainbow- smelt 27.3%, Atlantic men-haden 11.1%, winter flounder 7.5%. and Atlantic silverside 4.3%. Fish impingement rates in 1985 and 1986 were many times - - higher than in 1984 when the Pilgrim Station outage had both circulating water pumps off for a period of time.
- 2. In August 1986, Atlantic herring impingement accounted for 66.5% of this species collected. They have not been the most abundant species impinged on an annual basis since 1976, . but during 1986 they predominated.
- 3. The mean January - December 1986 invertebrate collection rate was 1.91+/hr with the blue mussel, sand - shrimp and horseshoe j crab accounting for 71.6%, 6.7% and 5.1% of the enumerated catch, respectively. Ten American lobsters were sampled, and 3
the invertebrate impingement rates in 1985 and 1986 were many times greater than recorded at Pilgrim Station during the 1984 outage year (lower circulating water pump availability).
- 4. Impinged fish, initial survival at the end of the Pilgrim Sta-tion intake slutceway was approximately. 19% during static screen washes and 60% during continuous washes. Only. three-dominant species showed greater than 60% survival.
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Fish Surveillance: Fish overflights in 1986 spotted four 'of five major species categories: herring, Atlantic menhaden, Atlantic mackerel and baitfish. Only one sighting of fish in the nearfield Pilgrim . vicinity was made. On November 22, 10,00,000 pounds of Atlantic herring were observed near Pilgrim but this occurrence was nat reported to regulatory authorities as the fish never entered the thermal plume, and no incidents occurred involving them. In 1986, as in 1985, there were no observations of pollock. Benthic Monitorirg:
- 1. Two new species of invertebrates were added to the list of blota for PNPS benthic surveys as a result of analysis of the-1986 samples. These were both annelid polychaetes sampled at the Effluent station.
- 2. No significant difference in species richness existed between the Effluent and Reference stations based on results of the 1986 sampling. However, the reference stations, which charac-l 1
teristically rank ahead of the Effluent station in species num-bers, did not in March and September 1986 when the discharge area ranked second and first, respectively. '
- 3. Review of overall faunal community structure, via cluster an-alysis, showed that the Effluent Station has a low degree of I-5
si:::11arity compared with the reference stations. Faunal clus-terings and algal community . overlap values continue to be consistent with past observations . showing general alteration of community structure at the Effluent site, even during Pil. grim's - 1984 and 1986 outages.
- 4. The warm-water species, Gracilaria tikvahtae, decreased in the area of the Effluent station during--1986 after it had normally -
colonized in 1985. It- was also rare in 1984, indicating a di-rect relationship to the lack of thermal effluent in 1984 -and 1986. Additional evidence of PNPS impacts in the Effluent discharge zone was the prevalent appearance of the cold water alga, Laminaria, in the Effluent area during 1984 transect map-pings.
- 6. Four observations of the near-shore acute impact zones were performed during this reporting period. Some changes 'in the size and shape of the denuded and stunted zones were detected.
as a result of the 1986 surveys. Thesa surveys noted a de-creased near-field impact area, due primarily to a sharp. re-duction in size of the Chondrus denuded zone because of new Chondrus growth within it. This evidence of. lagged recovery. from PNPS operational impacts, because of the outage ' of.1986, is similar to' what happened during the 1984 outage. Approx-imately six to .nine months is the time frame of response to the effects of PNPS -operation by' Chondrus in the' immediate discharge vicinity (within 95 meters of the discharge canal). I-6 ____u.. ._.__
Entrainment Monitoring:
- 1. A total of 37 species of fish eggs and/or larvae were found in the January - December 1986 entrainment collections (17-eggs, 35-larvae).
- 2. Egg collections for 1986 were dominated by Atlantic cod, fourbeard rockling and winter flounder (winter - early spring); Atlantic mackerel, fourbeard rockling and labrids (late spring - summer); hake, fourbeard rockling, labrids and Atlantic menhaden (late summer - autumn).
- 3. Larval collections for 1986 were dominated by sand lance, rock gunnel and grubby (winter - early spring); winter flounder, cunner, Atlantic mackerel, rockling and radiated shanny (late spring - summer); northern pipefish, cunner, black sea bass, tautog, and Atlantic herring (late summer -
autumn).
- 4. No lobster larvae were collected in the entrainment samples for 1986, and only nine have been sampled from 1974-1986.
- 5. In 1986 an estimated 1.696 x 10' fish eggs and 2.755 x 10* fish larvae were entrained at Pilgrim Station, as-suming full flow capacity of all seawater pumps. Eggs were dominated by the labrid - Limanda group, Atlantic mackerel and Enchelyopus - Urophycis - Peprilus group; and larvae by sculpin and Atlantic mackeral.
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- 6. The numbers of fish eggs collected in May and July 1984, and larvae in April, June and July 1984 were lower than for the same per.iods in all other years, including 1986. This may be attributed to the fact that both Pilgrim circulating water pumps were offline from April - mid August 1984, but at least one cir- culating water pump was operating during this period in other years.
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INTRODUCTION A. Scope and Objective
' This is the twenty-ninth 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 seventeenth semi-annual report in accordance with the environmental monitoring and reporting requirements of the PNPS Unit 1 NPDES Permit from the U.S.
Environmental Protection Agency (#NA0003557) and Massachusetts Division of Water Pollution Control (#359). A multi-year (1969-1977) report in-corporating marine fisheries, benthic, plankton /entrainment and im-pingement studies was submitted to the NRC in July 1978, as required by the PNPS Appendix B, Tech. Specs. Programs in these areas have been con-tinued 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.
)
The objectives of the Environmental Surveillance and Monitoring Program 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 Edison Company has committed to take steps to correct or mitigate any adverse situation. II-l
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 1986, and whose membership includes representatives from the University of Massachusetts, the Mass. Division of Water 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 l Committee' meetings held during this reporting period are included in Section V. B. Marine Biota Studies
- 1. Marine Fisheries Studies A modified version of the marine fisheries monitoring, initiated in 1981, is being conducted by the Commonwealth of Massachusetts, Division of ' Marine 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-lections (Figure 1) made at monthly intervals. In 1981, shrimp trawling and haul seining were initiated to provide PNPS impact-related sampling of benthic fish and shore zone fish, respectively. Shrimp trawling was done twice/ month at 4 stations (Figure 2) and haul setning twice/ month during May - October at 4 stations (Figure 1). II-2
i Monitoring is conducted of local' lobster stock catch statistics for areas off Rocky and Manomet Points (Figure 4). Catch statistics are collected approximately weekly 'throughout the fishing season (May-November). A finfish observational dive program was initiated in June 1978. SCUBA gear is utilized on biweekly dives from May-October (weekly mid-August to mid-September) at 6 stations (Figure 2) in the PNPS thermal plume area. A sportfishing creel census performed in 1983 and 1985 to determine the fishing effort, catch and economic value of this activity at the PNPS shorefront recreation area was terminated in 1986. In 1986, an experimental, lobster pot trawl monitoring effort was initiated to eliminate any clases associated with the collection of lobster stock catch statistics in determining PNPS effects. Eight 5-pot lobster trawls were fished in the thermal plume and control areas around PNPS (Figure 3.). Results of the marine fisheries monitoring and impact analysis during the reporting period are presented in Sections IIIA.1 and IIIA.2.
- 2. Benthic Studies The benthic monitoring described in this report was conducted by Battelle New England Marine Labs, Duxbury, Massachusetts.
II-3
The benthic flora and fauna were' sampled at three locations at' depths of 10' feet (MLN) (Figure 1). Quantitative (rock substratum) samples were collected, and the dominant flora and fauna in each plot were recorded. Sampling was conducted two times per year to determine - blotic changes, if any. Transet sampling off the discharge canal to - determine the extent of the denuded ~ and stunted zones is conducted four times a year (March, . June, Setpember -and December). Results of the benthic surveys and impact analysis during. this' period are discussed in Section IIIB.1 and IIIB.2.
- 3. Plankton Studies Since August 1973, Marine- Research, Inc. (MRI) of Falmouth, Massachusetts, has been monitoring entrainment in ' ' P11 grim 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 ef-fects of entrainment. These modifications have been developed by the
} contractor, and reviewed and approved by the Pilgrim A-T ~ Committee on the basis of program results. Plankton monitoring in 1986 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.l'and IIIC.2.
1 l II-4
- 4. Impingement Studies The Pilgrim I impingement monitoring and survival program speciates, quantifies and determines viability of the organisms carried onto the four intake traveling screens. Since January 1979, Marine Research, Inc. has been conducting impingement sampling with results being re-ported on by Boston Edison Company.
A new screen wash slutceway system was installed at Pilgrim in 1979 at a total cost of approximately $150,000. This new sluiceway system was required by the U.S. Environmental Protection Agency and the Mass. Olvision 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 Section IIID. C. Fish Surveillance Studies Weekly fish spotting overflights are conducted as part 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, II-5
dive inspections - have been conducted of the Pilgrio discharge canal in
~
order to evaluate fish ' barrier net durability, and effectiveness in ex-cluding fishes from the discharge canal. i-The annual summary report on fish overflights for 1986 is presented in-Section IVA. Barrier net inspections were not performed in 1986 as Pilgrim Station was in an outage since early April, and 'the net was removed from the discharge canal in August. D. Station Operation History l
. The daily average, reactor thermal power levels from January through December, 1982-1986 are shown in Figure 6. As can be seen, PNPS was in an outage for most of the 1986 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. 1986 Environmental Programs A planning schedule bar chart for 1987 environmental monitoring programs related to the operation of Pilgrim Station, showing task activities and milestones from December 1986 - June 1988, is included as Figure 7. II-6
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q ANNUAL REPORT ON
.)
MONITORING TO. ASSESS IMPACT OF PILGRIM NUCLEAR POWER STATION ON MARINE FISHERIES RESOURCES
-0F WESTERN CAPE COD BAY (CHARACTERIZATION OF FISHERIES RESOURCES)
Project Report No. 42 (January-December,1986) Summary Report No. 19 (Volume 1 of 2) By Brian C. Kelly, Vincent J. Malkoski, Steven J.-Correia, Robert P. Lawton, Mando Borgatti, and Buell Hollister April 15, 1986 Massachusetts Department of Fisheries, Wildlife, and Environmental Law Enforcement Division of Marine Fisheries 100 Cambridge Street Boston, Massachusetts 02202 e 4
TABLE OF CONTENTS
'Section Pm I. EXECUTIVE
SUMMARY
l~ II. INTRODUCTION 5 III. METHODS AND MATERIALS 5 IV. - RESULTS AND DISCUSSION 18 A. Physical (Abiotic) Factors 18
- 1. Power Output and Thermal Capacity 18
- 2. Discharge Current 18
- 3. Water Temperature 20 B. Fisheries 21
- 1. Commercial Lobster Pot-Catch Fishery 21
- 2. Research Lobster Trap Sampling Program 27
- 3. Nearshore Benthic Finfish 31
- 4. Pelagic and Benthi-Pelagic Fishes 40
- 5. Shorezone Fishes 46
- 6. Underwater Finfish Observations 52
- 7. Sportfishing 54 V. ACKNOWLEDGEMENTS 56 VI. LITERATURE CITED 57 VII. APPENDIX 59 e
i
+= . . ..
LIST OF TABLES A Trble Page
- 1. Monthly and annual percent sex composition of the commercial lobster 26 catch sampled in the vicinity of Pilgrim Station in 1986.
- 2. Average bottom water temperature ('C) and catch per trap-haul (CTH) 32 by week for all American lobster, and legal (> 81 mm) and sublegal
(< 81 mm) length categories sampled in the research lobster pot-catch study in the environs of Pilgrim Nuclear Power Station, 1986.
- 3. Expanded catch and percent composition of groundfish captured by 33 bottom trawling at four stations in the vicinity of Pilgrim Station, January-December, 1986.
- 4. Bottom trawl catch data for dominant groundfish occurring in the 35 i vicinity of Pilgrim Station, January-December, 1986. J
- 5. Annual mean catch rates for dominant groundfish trawled in the 38 l offsite waters of Pilgrim Nuclear Power Station, 1982-1986. l
- 6. Number, percentage composition, and size range of finfish species 42 captured by gillnet (7 panels of 3.8-15.2 cm mesh) in the vicinity of Pilgrim Nuclear Power Station, January-December, 1986.
- 7. Indices of relative abundance (catch-per-unit-effort) for selected 45 and pooled finfish species captured in western Cape Cod Bay near Pilgrim Nuclear Power Station based on standardized gill net gear (5 panels of 3.8-8.9 cm mesh) and procedures, 1971-1986. ,
l
- 8. Shore zone fishes captured by haul seine at four stations in the 47 vicinity of Pilgrim Nuclear Power Station, May-October, 1986.
- 9. Percent frequency of occurrence of selected shore zone fishes sampled 49 at four haul seine stations in the vicinity of Pilgrim Nuclear Power Station, May-October, 1986.
- 10. Monthly mean number of species per haul seine set for four stations 51 I sampled in the vicinity of Pilgrim Nuclear Power Station, May-October, 1986.
- 11. Abundance and size ranges associated with the occurrence of all species 53 observed during underwater observations, May-October, 1986.
11 -
LIST OF FIGURES i Figure P_ age
- 1. Distribution of-commercial lobster pots sampled in western Cape 6 Cod Bay, 1986.
- 2. Location of experimental lob' s ter gear (5-pot trawls) for Marine 8 Fisheries Studies.
- 3. Location of nearshore trawl sampling stations for Marine Fisheries 11 studies off Pilgrim Station.
- 4. Location of beach seine and gill net sampling stations for Marine 13
. Fisheries studies, and benthic studies sampling stations.
- 5. Finfish observational diving stations at PNPS discharge. 15
- 6. Creel survey interview form used at Pilgrim Shorefront to monitor 17 the recreational fishery, 1986.
i
- 7. Annual mean cumulative Pilgrim Station Unit I Capacity Factor 19 (MDC Net %) for 1972-1986.
- 8. Surface water temperatures averaged by season and area, 1983-1986, 22 in the vicinity of Pilgrim Station.
.- 9. Monthly commercial lobster catch per pot haul in vicinity of Pilgrim 25
! Station, 1986.
1
- 10. Summer size distribution of lobster captured in experimental trap 29 hauls in the Pilgrim area for 1986.
- 11. Seasonal mean trawl catch rates with vertical error bars for little 36 skate by station in Pilgrim area, 1986.
- 12. Seasonal mean trawl catch rates with vertical error bars for winter 39 flounder by station in Pilgrim area, 1986.
- 13. Seasonal mean trawl catch rates with vertical error bars for 41 windowpane by station in Pilgrim area,1986.
- l i
1 . l 2 l 111 l I O_
I. EXECUTIVE
SUMMARY
Commercial Lobster Pot-Catch Fishery Lobster catch statis'.ics were generated from 8,103 lobster (Homarus americanus) captured in 3,692 pot-hauls. The overall catch rate for all lobster (2.2) was similar to 1985's rate. Highest catch rates occurred in September and October. The annual catch rate of legal lobster (carapace length 2 81 mm and non-ovigerous) was the highest in the 16-year study. Lowest monthly legal catch rate occurred in July, and coincided with the summer molt period. Females comprised 58% of the total catch. The percentage of females ovigerous was greatest in April and November, and lowest in September. This seasonal periodicity of percent ovigerous females is an aspect of the repro-ductive cycle of the female American lobster. Research Lobster Trap Sampling Program We sampled 2,149 lobster from 1,868 trap hauls from 23 June - 2 October. Catches were dominated by sublegals ( < 81 mm carapace length) with an approximate 6:1 sublegal to legal ratio. Females comprised 49% of the catch, with the percent females ovigerous being 2.9%. The mean carapace length of lobster was 72.7 mm which is considerably smaller than the annual means of lobster caught in the commercial fishery in the region (1981-1986). The cull rate (20.4%), estimated by research fishing, was similar to that from commercial catches. Only 4 of 294 tagged legal-sized ( 2 81 mm) lobster were recaptured in our research traps, indicating that recapture of legals did not bias the legal catch rate. Recapture information, solicited from commercial lobster-men, supports previous findings that lobster movement in the inshore region of western Cape Cod Bay is generally localized. 1
Catch rates for both legals and sublegals were substentially higher in the commercial fishery when compared to the research study. Lobstermen allo-
^
cate fishing effort to maximize harvest, which may explain the higher commercial catch rates. Catches remained relatively low until July, peaked in August and declined into the fall. We found no correlation between ambient temperature and total catch rates. Nearshore Benthic Finfish A total of 3,506 fish, representing 31 species, was captured by bottom trawling in 1986. Five groundfish species: Little skate (Raja erinacea), winter flounder (Pseudopleuronectes americanus), windowpane (Scophthalmus aquosus), winter skate (Raja ocellata), and yellowtail flounder (Limanda ferruginea) comprised 89% of the total catch. Seasonally, catch rates for the numerically dominant species followed a similar pattern: catches were minimal in winter, peaked during spring and summer, and declined throughout the fall. Little skate ranked first in annual trawl catch and was the dominant finfish at all trawl stations except in the Intake. Mean annual catch rates for this species in 1985 and 1986 were similar, indicating no change in little skate relative abundance. Winter flounder ranked second in overall trawl catch. The mean annual winter flounder catch rate for the entire study area in 1986 was equivalent to 1985's value, suggesting an apparent halt to the recent decline in winter flounder relative abundance. Windowpane ranked third in trawl catch. 2
Pelagic and Benthi-Pelagic Fishes A total of.1,576 fish, comprising 26 species, was gill-netted. Overall menn CPUE was 99.6 fish / set, continuing the downward trend noted for lect several years. Pollock (Pollachius virens) and cunner (Tautogolabrus ad persus) comprised 66% of the total catch and were ranked first and second, rccpectively. Other dominant species were Atlantic herring (Clupea harengus h rengus), and tautog (Tautoga onitis), which comprised 8% and 6% of the total cctch, respectively. Overall, relative abundance for dominant species generally equaled or cxceeded 1985 values, although a mean CPUE value of 99.6 for pooled species w s one of the lowest recorded during the study. Shorezone Fishes A total of 9,272 finfish representing 26 species was haul-seined from May-October in the Pilgrim study area. Catch rates declined at all stations with the greatest decreases occurring at Warren Cove and Manomet Point. Seine cctches were highest at the Intake station and lowest at Manomet Point. The Atlantic silverside (Menidia menidia) accounted for 39% of the total catch, cnd, with the exception of the Intake station, was dominant at all seining sites. Other numerically dominant species were blueback herring (Alosa r stivalis), sand lance spp. (Ammodytes sgg,.), Atlantic menhaden (Brevoortin tyrannus), and winter flounder (Pseudopleuronectes americanus). Seasonally, saine catches were highest in late summer and early fall. Pilgrim Intake was similar to Long Point in total catch, species number, sp cies number per seine haul, and number of shared species. These similar-ities in abundance and species diversity are probably a function of the c:ai-enclosed nature of both stations. 3 l l
I l Underwater Finfish Observations During the period May through October, a total of 14 dives was made in the discharge area. Over 1,500 fish, comprising 8 species, were observed. Relative abundance approximated 1985 levels. The majority of fish (64.3%) were found in the discharge zone; 31% were sighted in the control zone and 4.6% in the stunted zone. Cunner was the species most commonly observed, totaling 79% of all sightings. Other common species were tautog and pollock. Few striped bass (Morone saxatilis) were observed by project divers. Sportfishing During the 1986 creel survey, approximately 500 fish were caught in 2,000 angler-trips. A total of seven species was captured, with three species cunner, vinter flounder, and bluefish (Pomatomus saltatrix), comprising 91% of the total catch. Anglers primarily used cast and retrieve techniques from the two discharge jetties, but still-fished with natural bait from the breakwater. Fishermen actively sought bluefish, winter flounder and striped bass. The greatest fishing pressure occurred in July and August and coincided with the period of highest catches. Overall catches were low relative to records from past years. 4
i
]
II. INTRODUCTION Environmental monitoring was conducted in 1986 by the Massachusetts Division of Marine Fisheries in a continuing effort to assess non-radiological offects of Pilgrim Nuclear Power Station upon the marine aquatic environment in the western sections of Cape Cod Bay, under Purchase Order No. 68297 to Boston Edison Company. Data from January-December, 1966 are analyzed and compared to past findings. It is noted that station outages began in early March; from 12 April through the rest of the year no waste heat was released into the environment, and only one circulating water pump was operated. Measurements, counts, percentages, and indices of relative abundance were used in this report to identify trends and relationships in the data by area end over time. III. METHODS AND MATERIALS Commercial Lobster Pot Catch Because of the large number of lobstermen trapping lobsters in the vicinity of Pilgrim Nuclear Power Station and the many landing sites along i the coast, it was impractical to monitor the entire local lobster fishery. Therefore, an index of harvest was obtained by sampling the catch of two cooperating commercial lobstermen who fish a large number of lobster pots in the environs of the power station. Sampling was conducted approximately weekly during the inshore lobster season by alternating lobstermen. To facilitate data compilation, the study area was partitioned into a grid of 0.8 km quadrats, with catch data recorded by quadrat (Figure 1). Thus, reference and surveillance areas could be identified and compared. Infor-mation collected included: catch of lobster per pot-haul; pot location 5
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74 g 121 70
# ' 28 gg 95 e 8 15 o 61 49
- 40 7 79
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Distribution of commercial lobster pots sampled in western Cape Cod Bay,1986. 6
'(quadrat); and for each lobster: carapace length (CL) in mm, sex, presence er sbsence of eggs (females), and molt condition. Data were verbally reported en tapes in the field and later transcribed to written records.
Research Lobster Trap Fishing We implemented an experimental lobster study in June of 1986 to clarify the relationship (interaction) between Pilgrim Station thermal output (opera-tional status) and lobster pot catch rate as an index of lobster abundance for the discharge area. When monitoring the catches of commercial lobstermen, we had no control over their selection of fishing grounds, gear, or distribu-tion of effort; thus, this scientific study was designed. Although we were to begin in early June, administrative problems precluded commencement until 23 June. Controlled research fishing was conducted in what diving surveys indicated to be ecologically similar reference and surveillance areas in the cnvirons of the power plant. Two reference areas were selected to measure natural variability and to be certain that the direction of change is the came in both unaffected locations. Population characteristics may vary within any designated reference area; therefore, measurements at a single site may be inadequate as a description for the entire area. Eight stations were campled - four (A-D) in the . surveillance area (quadrats I-11, I-12, and H-11) and four (E-H) in reference areas (quadrats G-12, G-13, J-11 and J-12) (Figure 2). Because of the plant outage, all sampling stations were monitored this year without the influence of waste heat on the environment. With only one circulating pump operating, the discharge current was reduced in velocity. This allowed us to compare pre-thermal stress data over time between both reference and treatment areas. The sampling period covered the months of high commercial catches, late June through. September. 7 , l
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( Figure 2 Location of experimental lobster gear (5 pot trawls) for Marine Fisheries Studies. 8
In late June, we set out 40 commercial vinyl coated wire lobster traps I (91 x 51 x 30 cm) in the study area. .Eight trawls (five traps / trawl; traps Epaced 'about 30 m apart;; trawl buoyed at each end) were deployed throughout 4 i the defined sampling strata establishing sampling stations which were system . matica11y fished so as to standardize the distribution of sampling effort. Pots, which were individually numbered, were hauled after one, two, and three day sets; soak-time (duration of a set) was always recorded. At , each station, traps were emptied of lobster and ady bycatch, rebaited, and redeployed. To standardize the effect of bait on lobster catchability, flounder i racks were used exclusively to bait the pots. Information was collected on
. number of lobster per pot. haul, and for each lobster, the location of capture,-
carapace length (CL) in mm (used to indicate lobster size), sex, status of claws, presence of eggs (ovigerous), shell hardness, and pathology were recorded. We released all lobster in the area of capture. To ascertain the recapture rate of legal lobster, we tagged all lobster > 81 mm CL prior to ( , their release with a coded yellow cinch tag placed proximal to the dactyi portion of the left cheliped to allow normal claw functioning. .The tagging study was announced to the general public and commercial lobstermen to enlist ' i their cooperation in obtaining recapture information regarding lobster move-ment. On a weekly basis, surface and bottom water temperatures were recorded at each station. 1 Water temperatures recorded in late June at surveillance Stations A, B, and D were essentially homogeneous on the surface and bottom, indicating. } good mixing throughout the water column; whereas, a 4 to 5 C difference i j between the surface and cooler bottom waters at Stations C (furthest station offshore) and E-H (reference) reflects ambient thermal stratification that
! 9 i
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- normally occurs in Cape. Cod Bay from June to November (Doret et a1.1973). .
! Presumably the lack.of temperature stratification in the Discharge area can be' attributed to the effect of the discharge current (minus waste heat)' from . ) Pilgrim' Station and resulting turbulence.. Trawl To monitor the nearshore demarsal finfish community in the Pilgrim area, u
; we continued small vessel (5-7 m) bottom trawling. Four stations were sampled i
(Figure 3). Biweekly = daytime trawling In the impact areas was conducted at surveillance Stations T-3 (Discharge) and T-6 (Intake).- The primary reference station was T-1, located in Warren Cove. Station selection was based on availability of suitable substrate for trawling, depth, sediment type, and known patterns of the thermal plume. { We opted for 15-minute tows, utilizing a 9.8 m Wilcox trawl (9.8 m sweep; 7.0 m headrope; with wings of 11.4 cm stretch mesh; and fitted with a 6.4 mm stretch mesh cod-end liner). Mean catch (no. of fish) per standard 15-minute tow or catch-per-unit-effort (CPUE) was used as an index of relative stock abundance. When uncontrollable factors prevented completion of a standard tow, catch values were extrapolated by use of a weighting function as_follows: C=C 1x t, t i where: C = expanded catch; C = the catch of the ith species of interest; . t = the standard tow time of 15 minutes; and 1 s the actual time of the tow to the nearest minute. t'= (tows < 10 minutes not counted) I j In processing the catch, standard survey techniques andf trawl log sheets
- were employed. All fish were identified, enumerated, and measured (fork length.
e l - FL; total length - TL) and then returned to the water. Surface and bottom temperatures were'taken at each station. 10
o 1 Q UMntT PT. CA Pt CCD LONG EAY BRACH L PL YMOUTM e ,q. , BAY N m 3CALE IN MitJ3
, T-1 RCCKY PQiNT
,,,s WARREM COVE T-3 7 6 y-,
WHITE MCMSE SgAcx MANCMRT PQIN T L10END O PCwtR PLANT SHRIMP TRAWL STATIONSIT) ' l 1 Figure 3 , Location of nearshore tral sau:pling stations for Marine Fisheries studies off Pilgrim Station. I 11
. . - - - - . = . -,
Gill Net , Pelagic and demersal finfish species frequenting the ledges that bracket the plant site were captured primarily to provide samples for radiation analy-sis. However, data records were kept by species, and inter-year comparisons of relative abundance made. We'used a sinking anchored monofilament gillnet. 3.0 m deep and 213.4 m long consisting of a " gang" of seven 30.5 m panels of the following mesh sizes: 3.8, 5.1, 6.4. 7.6. 8.9,-11.4, and 15.2 cm - l stretch. measure. An overnight set was made approximately monthly at a site parallel to shore along the 3 m depth contour (MLW), northwest of the terminus { of the effluent jetties (Figure 4), an area subjected to effects.of the Pilgrim ] Station discharge. To minimize sampling bias,-the end of the net positioned a nearest to the discharge canal was reversed on alternate sets. Surface and bottom water temperatures were obtained when the net was set and hauled. Haul Seine . Haul seining was employed to sample fish inhabiting the intertidal and shallow subtidal zones in the vicinity of Pilgrim Station. Fishes occurring in the nearshore area include forage species and the juvenile stages of-important sport and commercial species, which are integral components of community structure. We deleted Gray's Beach, Kingston Bay, from the sampling regime in 1986 because this location is truly estuarine habitat-and not open coastal marine. Four stations (Figure 4) were seined biweekly from May through October, a period when fishes traditionally populate the inshore area, following a , I standardized quantitative seining technique modified after Conover and Ross 1: (1982). The net used was a 45.7 x 1.8 m haul seine with a 1.8 ' x 1.8 x 1.8 m , l 1 bag (0.48 cm square mesh, #63 twine). Replicate hauls were usually made at i L
. 12 l
,-,_ -- _ _ , - - . ._ ~ .
Gurnet Pt. CAPE COO BA Y n 0 t/2 1 N -iis '* SCALE IN MILES Long 8each PL YMOUTH 8A Y eLYMOUTH HAR80n G-1 Rock y O Posnt G2
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l l Figure 4 . Location of Beach Seine and Gill Net Sampling Stations for Marine Fisheries Studies, and Benthic Studies Sampling Stations. 13
each station. Water temperature (approximately 1 m deep) and salinity were
- measured at the time of sampling.
At surveillance Station 3 (Intake), sampling was constrained by mainten-I ance' dredging conducted in 1982. To alleviate this problem, we began using a deeper seine at this site in late August of 1984. Set from a small outboard-
~
1 powered skiff, the. net measures 45.7 x 3.0 m with a 3.0 x 3.0 x 3.0 m pocket of 0.48 cm square mesh (#63 twine). At the beginning of each set, volume (m ) .of water seined was estimated i i from the depth and linear distance of the net from shore. Fish were enumerated i and measured; length data were obtained from at least 50 individuals' of each i species caught. Unusually large catches were subsampled to reduce mortality. j . l
-An estimate of the total number of individuals was made by multiplying the I subsample ratio (individuals per unit volume)- by the total number of volume-I units in the catch.
l 4 Observational Diving The underwater finfish observational study included standardized inspection 1 . of six selected stations (Figure 5) systematically undertaken by biologist-
- divers utilizing SCUBA. Dives were made at 2-week intervals from May through i
l mid-August, weekly from then until mid-September, and then biweekly through October as meteorological and hydrological conditions allowed. During each dive, two divers descended to the bottom and occupied each station where they recorded observations on marine biota, with major emphasis on finfish
~
(species, numbers, and size ranges). Water temperatures were also taken, and visibility estimates made. Stations designated a 'S', 'D', and 'C' were located in the ' stunted', ' denuded', and ' control' zones, respectively i-j (Boston Edison Company 1980) . This endeavor provided first-hand observations of finfish behavior and conditions seaward of the discharge canal barrier net. 14 yy, n--, - - ~ - - - , y +--,-y
1 A ~ 60* 1 A _ go __., CIA f eo-f 24 - 150' --. 2A I l b i ~'
! B reakwater l MLW N
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, \ l 1 1 i Figure 5 Finfish observational diving stations at PNPS discharge. 1 15
Creel Survey Sportfish catch at Pilgrim. Station's Shorefront recreational area in 1986 was monitored by security personnel at the waterfront in a cooperative effort with DMF to maintain at least a limited data base on the recreational fishery of this area. A questionnaire (Figure 6) and a sportfishing logbook were i employed to obtain creel data on number of fishermen, location of fishing, species preference, and catch. Impact Analysis To more clearly address power station impact on marine fisheries' resources
~
j in the surrounding waters of Cape Cod Bay, the PilgrLa Nuclear Power Station Unit I Maximum Dependable Capacity Factor (M.D.C. Net %) was compared to 1 assessment data (where applicable) in Volura II of this _ report. This output factor approximates thermal loading to the marine environment resulting in calefaction of cooling water drawn through the power plant. In 1984, with the plant not operating, there was essentially no waste heat released into the environment (0.1% HDC) and with -one or both (April to mid-August) circu-lating water pumps turned off, there was a reduced flow of water through the discharge canal. In 1986, the thermal capacity was 17.5%, the second lowest in the annual history of plant operation. For 10 months of this year, essentially only one circulating water pump was operating. The years 1983 and 1985 were of high thermal output ( > 80% HDC). To address plant impact, our time series analyses include data comparisons for reference and surveil-lance stations, for pre-operational and operational study periods, and for-
'I high capacity operational years (1983 and 1985) versus years of outage or i low output (1984 and 1986).
l i 16 l
{- 1
. Guard's Initials 1986 RECREATIONAL FISH SURVEY - PNPS SHOREFRONT Sheet Question:
Data Weather Wind direction & speed
- Number of anglers for the day Fishing locations Hours the Shorefront was open (e.g., 6 a.m. - 5:30 p.m.)
& fishing allowed.
-Specins Total number caught for the day ficunder (finefish) cerip:d bes bluefish end pollack tautes .
I macknrel cunner i (ma perch) 1 (otha.r) _ i COMMENTS: l Figure 6. Creel survey interview form used at Pilgrim Shorefront to monitor the recreational fishery, 1986. 17 t l l
\
IV. RESULTS AND DISCUSSION A. PHYSICAL (ABIOTIC) FACTORS s
- 1. POWER OUTPUT AND THERMAL CAPACITY .I J
To. assess power plant impact on marine resources in the environs of Rocky Point, Plymouth, we employed the Pilgrim Nuclear Power Station Unit'I Maximum Capacity Factor -(MDC Net %) as an index of operational output which roughly approximates thermal loading (calefaction) to the marine environment (100% MDC = 15.1 C above ambient water temperature, referred to asaT). Since inception of operation in July,1972, the annual MDC factor at Pilgrim Station 4 has ranged from a low of 0.1% in 1984 (essentially an outage year) to.a high of 84.4% in 1985 (Figure 7). The power level capacity also exceeded 80% during two other years, viz.1979 and 1983. In this report, we have stressed - data comparisons from 1984 and 1986 (17.5% annual MDC)1with the two years (1983 and 1985) of high operational output which alternate with the former two low output or outage years. Pilgrim Station has operated over the years at a mean annual MDC factor of 52.9% (8.0 C above ambient) or at just over half its possible output. With this operational regime to date, we may not have fully realized the potential of plant impact. w
- 2. DISCHARGE CURRENT At the Pilgrim aite, localized currents are induced by the plant's circu-l lating water intake and' discharge. This once-through' cooling system releases i a current of water which has a scouring or abrasive action on the benthic environment. An interaction of environmental' factors, including temperature,
' salinity and currents is important in influencing the occurrence, distribution,_
i j and abundance of marine life. During the plant outage of 1984, one or both 18 - 2
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0 . . i , , , , , , , , , 7 , , 72 73 74 75 76 77 78 79 80 81 82 83 .84 85 86
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15 year x - *** (52.9%) Annual x.......... Figure 7 Annual mean cumulative Pilgrim Station Unit I Capacity Factor (MDC Net %) for 1972-1986. l 19
, . . .-r,n
circulacing seawater pumps were turned off (i.e., no circulating seawater pumps were in operation from late March to mid-August,-and one pump was operated l
' otherwise) thus eliminating or reducing the offshore discharge current. In 1 l
1986, two pumps were operated from the beginning of January to 9 March; there- ;
- \
after through the end of the year only one pump was utilized.
- 3. WATER TEMPERATURE In the inshore area of western Cape Cod Bay, we have recorded ambient water temperatures ranging from -1 C in' February to 23 C in August at the surface and -1 C in February to 21 C in September on the bottom. Surface-waters begin warming in March or April, and a thermocline forms at-between 5 and 10 m in June. Thermal stratification continues until November, when the water column becomes essentially isothermal (Doret et al. 1973; Lawton l
et al. 1985). Surface to bottom temperature differentials have. ranged from ; 0.5 C to 4.7 C. The highest monthly average water temperature (ambient).for western Cape Cod Bay between 1970 and 1986 was 18.8 C, obtained for September of 1974. The maximum surface temperature was recorded in August of both 1973 and 1984 at 23 C. Ambient water temperatures for spring and summer J were higher in the nearby estuary - Plymouth. Kingston, Duxbury Bay - reaching 25 C in the shallows during summer. Temperatures in Pilgrim Station's thermal plume, with the plant fully operational, have peaked at 32 C (surface and bottom).
- Mean surface water temperatures by season and area in the~ Pilgrim vicinity for 1983-1986 are found in Figure 8. Seasonally each year, tempera-ture profiles were most comparable for spring and autumn. Overall, water temperatures were highest in 1983 and lowest in 1984. The annual temperature 1
i 20 i 'l
- . . . - - , . _ _ , ,,. . . , - . . --_ _ % . _ . _ , ,, ., , - - . . - , . , , , e-, -
-i..yy _
regime in 1983 and '1985 exhibited'similar patterns but with somewhat lower values for the latter. On the'whole, water-temperatures were lower in 1986 than in'1983 and 1985. Most noteworthy was the markedly lover ambient water i- . temperatures found during all seasons of 1984 in the Pilgrim. area. We specu-i
- . lated that lower commercial lobster catches in 1984 were related to reduced
- . molt probability and resultant lowered recruitment caused by the cooler >
conditions (Lawton et al. 1985). As expected in 1983 and 1985 ( > 80% power plant capacity) in- the . study area, seasonal water temperatures were highest in the discharge area (Figure 8) i ! because of the addition of waste heat to the waters contiguous to the-power plant. The extent of the near-field. region delineated by the discharge flow-effect included a 1.100 m to 1,400 m " denuded" zone attributed primarily i . . to scour in the immediate path of- the discharge -current and a peripheral 2 crea of " stunted" algal growth of about 1,900.m 2to 2,900 m due primarily' to the thermal component (excess temperature) of the plume (Bridges and Anderson i , 1984). In summer with the power plant at 100% operating load, we have [ measured a temperature differential git) of about 15 C between discharge and. j ambient waters. Conversely, in 1984 (outage year) and 1986 (plant outage. l April-December), temperatures in the discharge most reflected ambient levels I at Rocky Point, with seasonal means in the discharge zone never being the ,I highest of the study area. f i B. FISHERIES
- 1. COMMERCIAL LOBSTER POT-CATCH FISHERY l
Monitoring the commercial American lobster .(Homarus americanus) fishery in the Pilgrim study area began 29 April and concluded 24 November,1986.
~
21
1983 , I l 25 - WINTER SPRING SUMMEA FALL, I I I
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l l l l 1 I i 1 I l i I i I I E 15 - I , 1 I t I I I
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J l .l .t 1 1 I i i e 1 2 3 4 5 ! 1 2 3 4 5 l 1 2 3 4 5 I 1 2 3 4 5 an an an au l Area Rey
- 1. Grays Beach & Lons Point
. 1984 2. Warren Cove & Rocky Point .
- 3. Discharge
- 4. Intake-
- 5. White Horae & Manomet Point 25 -
VINTER SPRING SUI 9tER FALL i I I l I I I I I I 2o . I I I I I I I I I I o I l I l 2 15.- i l , I
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. t o 6 ' 1 2 3 4 5 1 2 3 4 5 l t 2 3 4 5 l 1 2 3 . 5 l AREA AREA AREA AREA Figure 8. Surface water temperatures averaged by season and area, 2
1983-1986, in the vicinity of Pilgrim Station. 22
- - 1985 25 -'
WINTER , SPRING $UMMER ' FALL f l 'l. g I l - l 20 - . g g . I I g i 1 , o i I i
,15 - 1
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.5. I I I I I I l.
I I l 3 l. g I I 0 l 4 5 4 1 2 3 4 5 l 1 2' 3 4 5 1 2 3 l 1 2 3 5 l MM ARM - MM ARM l Area Kay
- 1. Craye Beach & !.ong Point
- 2. Warren Cove & Rocky Point
, 3. Discharge
- 4. Intake 1 1986 5. White Horse & Manomet Point i
ut m R I sFRzuc sumst i FAtt. I a i i I 2L. g i I I I I -1 I I I 1 I i I 20- I I 1 1
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?
I ! J l I i : I ! I I I e > > : 3 - 3 i t : 3 .. 3 i i 2 . 3 . . ... . .. ASEA AREA MtEA . nya Figure 8. Surface water temperatures averaged by season and area, l 1983-1986, in the vicinity of Pilgrim Station (continued).. 23
Lobster catch statistics and biological data (i.e., length. - sex, shell hardness) were collected for the 7-month investigation during 20 sampling trips aboard two commercial lobster boats. Data were recorded for 8,103 lobster taken during 3,692 lobster pot-hauls. Overall catch per pot for 'all lobster (legal, sublegal, and ovigerous females 2 81 mm) for the Pilgrim area was 2.2, a rate similar to the catch-per-unit-effort (CPUE) of 2.0 in 1985. Lobster catch by month in the study area l ! is shown in Figure 9. Highest monthly overall CPUE occurred in September i and October (2.93 and 3.29,Lrespectively). I Summaries of legal lobster (carapace length 2 81 mm and non-ovigerous) catch per pot haul and other lobster statistics for the study area are tabu- ] lated in Appendices A and B. One-third of the total catch were legal lobster (2,852). The annual-legal catch rate of 0.77 was the highest of the 16-year i study. Coastwide, marketable lobster catches per pot haul for 1986 were substantially higher than in 1985 (Bruce Estrella, personal communication) . The lowest monthly legal catch rate occurred in July (0.43). This decline is characteristic of the summer molt period in Cape Cod Bay, when lobster are less susceptible to capture by fishermen due to decreased movement. I ! The highest monthly legal catch rate (1.16) was recorded for September. Sub- j legal monthly catch rates paralleled that of the overall lobster CPUE (Figure 9). i Females comprised 58% of the annual catch (1.4 females to 1.0 males) and ! dominated in every month of'the study (Table 1). There were 85 ovigerous B. Estrella, Senior Marine Fisheries Biologist, Coastal Lobster Investigations. Massachusetts Division of Marine Fisheries, Sandwich, MA. i 4 24
- _ _ . . -a.-_,,._ . _ - _ . , _ . . __ __ _ - , . _ _ _ - .. _
4 1 Ir MONTHLY LOBSTER CATCH /POTHAUL
- 3.5 - .
3-2.5 -
, o .
D 2-E z o 2
$ 1.5 -
05 m 9 1-0.5 - E TOTAL LOBSTER O LEGALS , 0 9 SUBLEGALS , APR MY JNN JNL ANG SdP OCT NOV-MONTH I l . 1 f t Figure 9. Monthly comercial lobster catch per pot haul in vicinity of Pilgrim Station, 1986. 25 i
# y - -
e,_, - , . , . - - . - _ - - , , , - _ . , , , - - - - - . _.,.-,y r, - - - - , - - - -
m Table 1. Monthly and annual percent sex composition of the commercial lobster catch sampled in the vicinity of Pilgrim Sta, tion in 1986. April May June July August Sept .Oct Nov Annual Male 29.2 38.9 42.4 39.9- 44.0 45.0 42.8 30.3 42.0 Female 70.8 61.1 57.6 60.1 56.0 55.0 57.2' 69.7 58.0 I i i I l e l i 26 o
m _ _ _ _ __ _ __ ______ (egg-carrying) females sampled (1.0% of the entire catch), of which 39 were less than 81 mm in carapace length. The overall percentage of females ovigerous was greatest in April (4.7%) and November (4.5%) and lowest in summer (0.7% in September). This seasonality of percent ovigerous females is an aspect of the two-year reproductive cycle of the typical female American lobster'(Aiken end Waddy 1982). The female lobster will generally breed,after the summer molt, but not extrude the fertilized eggs until fall of the following year. The eggs are then carried throughout the winter and hatch out in spring.
- 2. RESEARCH LOBSTER TRAP SAMPLING PROGRAM j
During the period of 23 June through 2 October, 1986, we conducted con-trolled research lobster (Homarus americanus) fishing in the environs of Pilgrim Station (Figure 2). Fifty sampling days were completed during which 2,149 lobster were sampled from 1,868 trap hauls. In thirty-eight percent of the trap-hauls no lobster were caught. The samples were predominantly composed of sublegals ( < 81 mm carapace length - CL). Of the total catch, only 305 lobster were legal-sized ( 2 81 mm CL), with the ratio of sublegal to legal 6.05:1. The number (legal a_d sublegal) caught per trap haul ranged from 0 to 9, with legals ranging from 0 to 3 and sublegals, O to 8. Females comprised 49.3% of the research catch in shoal waters for an over-all sex ratio that approached 1:1 (actual ratio was 1 female to 1.03 males). However, females (58%) outnumbered males in the commercial lobster trap catch survey in western Cape Cod Bay. Briggs and Muschacke (1979) found a J higher proportion of females at 9.1-18.3 m depth in Long Island Sound, while at shallower depths, males predominated. There were 31 ovigerous (egg carryingi females captured of which 24 (77%) were sublegal. The percentage of females J 27
ovigerous in our research catches was 2.9%, whereas the percent females ovigerous sampled in the commercial catches of the area was 1.8%. Lobster ranged in size from 40-120 mm CL. The mean carapace length of all lobster sampled was 72.7 mm. This is considerably smaller than the average sizes of lobster (79.3-80.0 mm CL) caught in the commercial fishery of western Cape Cod Bay from 1981-1986. Pot design, fishing pressure, and characteristics
- )
of the habitat may influence the size composition of the catch. Commercial ' l lobster pots are designed to retain lobster of legal size but do catch sub- , legals, though not necessarily in proportion to their true abundance. Krouse ; 1 (1973) and Krouse and Thomas (1975) reported that lobster were vulnerable to ! 4 capture by the gear upon reaching a carapace length of from 70-75 mm CL. As i to fishing pressure, Krouse (1973) found an inverse relationship between I effort and size composition of the catch. Several researchers have observed a positive correlation between size of the lobster and size of the available shelter sites in their habitat (Cobb 1971). A length-frequency histogram of all lobster collected in the research i study area for 1986 was compiled (Figure 10). The effects of availability, i.e., spatial distribution of individuals of the species sampled, vulnera-bility, i.e., the inability of the species to escape capture when encountering the gear, and high rate of exploitation by the local fishery on our catches are manifested in the histogram. The stepwise increase in catch of lobster up to approximately 76 mm CL would suggest this represented the size lobster which is fully vulnerable to our gear. Reduced catches below this carapace length probably result from gear selectivity (escapement) and the reduced availability of small lobster (40 mm CL). The marked reduction in numbers greater than the minimum legal size (81 mm CL) reflects the influence of intensive commercial harvesting. 28 i s
>--g -y- %,y..-----.y.w g .m---M ^@ r: 7"-~-- wr y -,a m y-e - --
ts is . 14 - 12 - 12 - 1 I I 11 g G I to . I U l E 9- l i 5 ta I l E ! s 7-r- 81 i m H I
$ 6- 1 E r- I l
_ l 5- - p. m I I 3- { g X 2-t- I a a i a e i . . . i p i . . . . , 42 46 50 54 58 62 66 70 14 78 82 66 90 94 98 102 106 CARAPACE LENGTH (mm) i Figure 10. Summer size distribution of lobster captured in experimental trap hauls in the Pilgrim area for 1986. Legal-sized lobster are > 81 mm carapace 4 length; sublegal-sized lobater are < 81 mm carapace length; x is mean carapace length. 6 29 r I l l
The percentage of culls (lobster with missing or regenerating claws) sampled in research fishing during 1986 was 20.4% which is representative of the area as a whole, in that the cull rate in commercial catches was 21.6%. The overall trend in the commercial fishery of the region reveals an increasing number of culls over the period'of 1981-1986 (Estrella and McKiernan 1986). Possible causes include increased use of large mesh wire lobster traps and
- the elevated effort in the trap fishery (Estrella and McKiernan ibid).
We tagged 294 legal-sized lobster captured in the research traps primarily to obtain unbiased estimates of legal catch in the trap-hauls (recaptures could then be discounted). We ourselves, recaptured only 4 (1.4%) of the total tagged. Including the tag return's from other lobstermen, 105 marked lobster were recaptured, representing 35.7% of the total tagged. From recapture infor-mation solicited from cooperating lobstermen and dealers, we were also able to obtain information on movement of legal-sized lobster in this inshore. region of Cape Cod Bay. Most were recaptured within 0.8 km of Pilgrim Station, demonstrating very localized movement in a northerly or easterly direction. The longest distance traveled was to the backside of Cape Cod off Wellfleet. This information supports that of Fair (1977) and Lawton et al. (1984) demon-strating that, overall, lobster movement in the western inshore region of Cape Cod Bay is generally localized. Catch per trap haul (CTH) was examined as a measure of catch-per-unit-effort. The overall mean CTH for lobster of all sizes and both sexes pooled was 1.15; for legals, 0.16; and for sublegals, 0.99. Catch rates obtained from the commercial fishery in the Pilgrim area were: overall, 2.2 CTH, legals, 0.77 CTH, and sublegals, 1.43 CTH. It is readily apparent that catch statistics for the commercial fishery were substantially higher than from our 30
+ . ._ . . . _-
research' study. Furthermore, the sublegal to legal catch ratio was alaost three times greater in the research catches. A credible explanation is that 4 l commercial fishermen are concerned with maximizing their harvest of legal 4 lobster and not with conducting a scientific investigation. Lobstermen are constantly relocating their pots (distribution of effort) according to where they believe,there are concentrations of legal lobster. Examining the relationship between ambient bottom water temperature and cxperimental trap catch rates, we found no correlation between temperature i cnd total catch rate (r = -0.3422), temperature and. legal catch rate-1
! (r = -0.2038), and. temperature and sublegal catch rate (r = -0.3942). By week, the CTH averages for all lobsteri legals, and sublegals are found in Table 2.
The general trend was for relatively low catch rates until mid-July, when } following the molting period, catches, augmented by recruitment, elevated j through most of August.. A gradual decline then followed into fall which may be due to fishing effort, temperature iriluence on lobster activity, and/or offshore movements of lobster. i l
, 3. NEARSHORE BENTHIC FINFISH l
1 We completed 123 bottom trawls in the study area from 2 January to. 30 December, 1986. Four stations (Figure 3) were sampled biweekly except in February and March, when sampling was conducted monthly due to adverse weather j conditions. Station 7 (Rocky Point) was dropped at the end of 1985, due to 1 depth differences from the other stations and congestion from lobster pots L during the inshore lobster fishing season. ! A total of 3,506 fish, representing 31 species was collected in 1986 j l j (Table 3). The average catch per tow (or catch-per-unit-effort, CPUE) for I I l 31 4 1 g 9
Table 2. Average bottom water temperature (C) and catch per trap-haul (CTH) by week for all American lobster, and legal (2 81 m) and sublegal (< 81 m) length categories sampled in the research lobster trap catch study in the environs of Pilgrim Nuclear Power Station, 1986. A Bottom Week Water Temp. (C) All lobster 181 m < 81 m 6/22-28 12.6 0.78 0.19 0.59 6/29-7/5 - 0.81 0.16 0.65 7/6-12 16.6 0.86 0.15 0.71 7/13-19 13.2' 1.33 0.24 1.09 7/20-26 14.2 1.13 0.13 0.99 7/27-8/2 18.0 1.26 0.12 1.14 8/3-9 15.1 1.77 0.26 1.51' 8/10-16 13.9 1.66 0.14 1.52 8/17-23 20.3 1.70 0.16 1.54 8/24-30 18.1 1.37 0.18 1.19 8/31-9/6 14.2 1.08 0.20 0.88 9/7-13 -
'0.95 0.15 0.80 9/14-20 14.2 0.78 0.18 0.60 9 21-27 15.2 0.85 0.13 0.72 9/28-10/4 -
0.56 0.09 0.47 32 9
Table 3. Expanded catch and percent composition of groundfish captured by bottom trawling at four stations in the vicinity of Pilgrim Station, January-December, 1986. Species Sta. 1 Sta. 3 Sta. 4 Sta. 6 Totals % catch Little skate 222.6 284.6 398.6 ;272.3- 1178.3 33.6 i Winter flounder 133.0 1212.1 317.4 " 442.3. 1105.0 31.5 Windowpane 183.8 112.9. .; 121.1 :144.7~ a 562.6 16.0 Winter skate 43.3 47.2 .i 85.5 30.8- 207.0 5.9 Yellowtail flounder _1.0 J 36. 7 < 1 23.9 :19.9 81.6 2.3 i White hake 0.0 <
-- 28.7 f 12.5 36.4 77.6 2.2 Red hake 17.1 -10.11 5.7 <22.6 -
55.5 1.5 Atlantic silverside 10.0 ;5.3 , 15.3 12.8 > 43.5 1.2 Scup 15.0 -
?0.0J >
12.0 0.01 i 27.0 0.7 Rainbow smelt 21.0 m l2;6' Ji 1.1 -
'2.2. g 26.9 0.7 Cunner 8.0 s- .'2.2 8.2 - 5.0 ' 23.6 0.6 Atlantic cod 2.0 ,, ':6.2 6.0 ;2.0 7
'i 16.2 0.4 Ocean pout 6.0 2.5 : 5.6 : 0. 0 ._ 14.1 0.4 Longhorn sculpin 3.0 '
_ 21.5 - j 3.7 -6.2J . 14.5 0.4 Summer flounder 3.0 4.81'l 1.1 ,3.0' 12.0 0.3 Blueback herring 2.0 (8.1- , 0.0 10.0: 10.1 0.2 i Northern pipefish 3.0 ~ 1.0 2.0 ~1.1 7.1 0.2 Ro'ck gunnel 1.0 2.0 1.0 16.1 10.1 0.2 Northern puffer 1.0 3.5 1.0 4.2 9.7 0.2 Atlantic herring 1.0 0.0 0.0 0.0 1.0 0.0 Atlantic tomcod 1.0 0.0~ 0.0 0.0 1.0 0.0 Black sea bass 1.0 l0.0 0.0 0.0 1.0 0.0 Butterfish 2.0 0.0' O.0 1.0 3.0 0.0 Fourspot flounder 0.0 '0.0 0.0 1.0 1.0 0.0 Goosefish 0.0 0.0 0.0 1.0 1.0 0.0 Grubby 0.0 0.0 1.1 1.0 2.1 0.0 Northern searobin 2.0 ~0.0
- 1.0 0.0 3.0 0.0 Pollock 0.0 ;0.0 ,
0.0 2.0 2.0 0.0 Seasnail 1.0 0.0 4 0.0 0.0 1.0 0.0 Silver hake 3.4 0.0 ' O.0 '0.0 3.4 0.0 Tautog 0.0 2.0 0.0 1.0. 3.0 0.0
' Pooled Species Number of species 25 19 20 22 31 Number of tows 31 33 33 12 6 123 Total fish 687.5 774.6 1024.5 1019.5 3506.1
, Catch / tow 22.1 23.4 31.0 39.2 28.5 Percent catch 19.6 22.0 - 29.2 29.0 Shaded columns are data collected at surveillance stations. 1C atch rates were expanded for tows less than the standard 15-minute duration. 33 i l l l
all species and stations pooled was 28.5. The~ surveillance station in the Intake embayment (Station 6) and the reference station off White Horse Beach (Station 4) yielded the highest CPUE (all species pooled) of 39.2 and 31.0, respectively. Five groundfish species - little skate (Raia erinacea), winter
~
flounder (Pseudopleuronectes americanus), windowpane (Scophthalmus aquosus), winter skate (Raja, ocellata), .and yellowtail flounder (Limanda ferruginea) - comprised 89.3% of the 1986 trawl catch. Skates Little skate, comprising 33.6% of the trawl total, ranked first in annual i trawl catch abundance in 1986. Mean annual catch per tow of little skate for all stations pooled was 9.6, as compared with 9.7 for these same four stations in 1985, indicating no change in stock size for the area. As in 1985, this species was the dominant finfish trawled at all stations except the Intake embayment. The highest annual station catch rate occurred at White Horse Beach (Table 4) for the fourth consecutive year, primarily due to high spring l catches at this location (Figure 11). Station 1 had the lowest annual CPUE of little skate with 7.1. 1 l Little skate seasonal catch rates exhibited a similar overall pattern i at each station of very low values in winter, a substantial increase.to peak catches in spring / summer, followed by a decline in fall (Figure 11). Seasonal 4 peaks of little skate abundance occurred at Station 4 (22.1) in spring, , Station 6-(18.2) in summer and Station 4 (7.7) in fall. ; l Winter skate ranked fourth in total abundance (5.9%, all stations pooled) l for the second year in a row. Mean annual catch was highest at Station 4 l (2.5). 34 4
. - - - - ,,, , - - . . . -, . - - - - , .~ .-,v.--. -e p -
l l 1 l Table 4 Bottom trawl catch data for dominant groundfish l occurring in the vicinity of Pilgrim Station, 1 January-December, 1986. I l winter yellowtail little winter flounder flounder skate windowpane skate STATION 1 Mean catch / tow
- 4.2 0.0 7.1 5.9 1.3 Me:n size (cm) 28.0 9.0 37.0 22.7 41.2 Siza range (cm) 6 - 40 9-9 11 ---51 9 - 33 35 - 37
~3 m7mm,-,7mm -m m-m7 emy- w% -
y g- , s ,
< ~
< e; .
a
.,.i (826 ,
' ' ~1.4 Mesa catch / tow *. . [654' . 1.11 13.42 -
^21;7-~
MeanLsize.(en)_ c 127.8 -
- 28. 2-? ; 37.lf ::i-x 142.7
!8- 455 ,
Size range (ca)': , L12_--37 jl61-!53J 6332Q (32;-- 82, u .u. .=w.u an-~s:.uzs u aa a a:. . . www.2 unn a > ~~ "~ - ~~ ~ 4 STATION 4 Mern catch / tow
- 9.6 0.7 12.0 3.6 2.5 Mern size (cm) 28.6- 27.2 39.0 22.4 41.5 Siza range (cm) 7 - 44 9 - 35 19 - 54 10 - 36 32 - 71
,,, s nag,, ; ~ , _ , ,, , n . - , . , n y y .. ,_- - . ,. g.y ~. m . -
,- g n STATION 6 .
Mean cathh/ cow *? ^ k l720:1 :2037:J ' -10.'47 - S i5.: fil1~ Maan size .(cm)i 1-26.9 . '28.3
, . - f 38'.'7. -~ (20.8 243.0 Size range 1(em); 3 46' -
15'- 39 -- 13. - 153 -- l2.- 34; 36'--55 (m
' ~
a; - :p Shaded rows are data collected at surveillance stations.
- Catch rates were expanded for tows less than the standard 15-minute duration.
l I i
)
1 l 35 1
Little Skate 1 l Winter ! Spring I Summer l Fall T. . . 25 -- 27.9 - l l Station Key l
- 1. Warren Cove
- 3. Discharge --
20 - 4. White Horse ..
- 6. Intake ..
1
~
E 15 ' < _ m.y t w lg u A : - I -- :: .. 10 ~ I - l l
~
l F fi4 [ 75 i: I i kl l t i 1 34 6 1 3 4 6 1 3 46 1 34 6 Station Station S tation Station Figure 11. Seasonal mean trawl catch rates with vertical error bars for little skate by station in Pilgrim area, 1986. i 1 3o
Winter flounder 4
. Winter flounder ranked second in overall trawl catch (31.5%, all stations pooled) for the study area. The mean CPUE for all stations combined was 9.0 j for the.second year'in a row. The recent decline in the relative abundance
. of winter flounder in the Pilgrim Station area (Table 5) appears to have .
abated. Indices of winter flounder abundance (mean weight and mean number per l i tow) generated from coastal spring bottom trawl surveys conducted by the i Resource Assessment Project of the Massachusetts Division of Marine' Fisheries i i also connote a coastwide stabilization of the population in 1986, following a-i 4-year decline (Howe et al.1985; A. Howe, personal communication)2 Station 6 i ranked first in winter flounder catch abundance, with an annual mean CPUE of- $ 17.0; Station 1 ranked last with an annual mean CPUE of 4.2. Winter flounder seasonal catch rates at each station (Figure 12) followed 1 l a similar overall pattern: minimal catches in winter, peak catches in spring / aummer, and reduced catches in the fall (with the exception of Station 1 . which had its maximum value in fall). Station 6 had the greatest winter L flounder catch rate for each season. 1 Windowpane ] Windowpane was third overall in annual trawl catch (16%) for-the fifth j consecutive year. The mean annual CPUE for all stations pooled was 4.6, up i i from 3.3 in 1985 and thus ending a 3-year decline in catch. Spring catch indices from the Division's coastal bottom trawl survey increased in 1986, reversing a 3-year trend of diminishing abundance (Howe et al. 1985; A. Howe, personal communication) . The highest annual CPUE for windowpane (5.9) was 4 ! 4 2 l A. Howe, Senior Marine Fisheries Biologist, Resou'rce Assessment Project. ? Massachusetts Division of Marine Fisheries, Sandwich, MA. l i 37 i 4
...-..--m__..-.-,.~,.-.~-.--m,_--. . _ . - . . - , - - - _ - . - - - - . - - - . . , m . - , . --. _ _ _ _ _ - _ _ _ . . ,- - - - - - .
Table 5. Annual mean catch rates for dominant groundfish trawled in the offsite waters of Pilgrim Nuclear Power Station, 1982-1986. Station 1 (Warren Cove) winter yellowtail . little winter Year flounder flounder windowpane skate skate 1982 15.6 1.4 4.3 4.4 0.0 1983 26.3 0.0 6.8 6.2 0.9 1984 12.7 0.5 5.6 5.4 2.0 1985 7.1 0.1 5.7 6.9 1.7 1986 4.2 0.0 5.9 7.1 1.3 Station 3 (Discharge) winter yellowtail little winter Year flounder flounder windowpane skate skate ( a, .s , ,,
,s
.,;.:.g . , . . . . . . 'c s
'" :.: .;..s,..s..s. -
M!!' ' - , , s ?djiE$hs. d [' 'l!!!!M!k..,.!l!; .. ' 'ihN.. = -!!h 'j!!N.: h :!!: !!! M3$!' s ',..!!![ ' !!!!R2li!!s,'. ~ j@$$$[$ {194$1 , '.
. 12176R i3,64 2
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, y!Mi,
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#'Esiss '
iiss!!!. .ii$ij!! ; i!!{$$i!!! !!!!$sj$.
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fiess;!!!' :' , s ' nsiti? i tsiMs!! i
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iiihi!i!! ijjgstilij 's !!!$yglji! '^ ii!!jg?; Station 4 (White Horse Beach) winter yellowtail little winter Year flounder flounder windowpane skate skate 1982 9.8 5.6 7.4 6.8 0.2 1983 17.8 2.4 3.8 13.3 1.8 1984 7.1 3.2 4.5 12.3 1.7 1985 8.0 2.0 1.5 13.7 1.8
'986
. 9.6 0.7 3.6 12.0 2.5 Station 6 (Intake) winter yellowtail little winter Year flounder flounder windowpane skate ' skate ti?.> . ,, . ,
' ~ > ,s , <
l1982][' , isN!? 'gs;e
^
seis ??Ms! !1. 98.3.,-o
$...m
' ., s s. ~ .. !.?.m'n..r:.s.:i :.:-
S. .W... #,. .
, s.iiM, m ...,is! ' ,,
s:.:.--
~~ ' -
?
, 4 .
No data collected during years 1982-1983 at Station 6. Catch rates were expanded for tows less than the standard 15 minute duration. 38
l l Winter Flounder Winter l Spring !Sumer T I Fall 25
, t .9 29.1 20 - Station Key -
- 1. Warren Cove ~
- 3. Discharge' --
- 4. White Horse
- 6. Intake 0 15 -
s
~
j -- a s.
- 7 pQ ..
10 - f _t - I g - k
.r
~%
5~ $$ '~
~
T $.i
^I 7:
a $,
- -3 1 e} -%
iN . 3 , i 1 3 4 6 1 34 6 1 346 1 3 4 6 Station Station Station Station Figure 12. Seasonal mean trawl catch rates with vertical error bars for winter flounder by station in Pilgrim area, 1986.
*t, a
39
L 4 recorded at Station 1 in Warren Cove for the fourth consecutive year. The I lowest annual CPUE (3.4) for this flatfish occurred at Station 3. Windowpane seasonal catch rates at each station (Figure 13) followed a general pattern of minimal catch in winter, maximal catches in spring / summer, and reduced fall catches (Station 4 is an exception,'where fall catch exceeded summer's value). Yellowtail flounder Yellowtail flounder ranked fifth in annual relative abundance (2.3%) for the third consecutive year. The annual mean CPUE of all stations pooled was > 0.7, down from last year's catch rate of 1.3 for the same stations. Yellow-tail abundance along the Massachusetts coastline has been declining since I 1982 (Howe et al. 1985). This flatfish was most abundant at Station 3 (Dis-charge) where the annual mean CPUE was 1.1, and least abundant at Station 1 I (CPUE < 0.1). t 4. PELAGIC AND BENTHI-PELAGIC FISHES i I A total of 1,576 fish, comprising 26 species was gill-netted during 14-overnight sets made in 1986 (Table 6). Inclement weather precluded _ sampling. in February, but at least one set was made during the other months; two sets ;
! were made in March, September, and October. Annual mean CPUE or catch-per-i.
! unit-effort (catch per overnight set) for pooled species was 99.6 fish / set . i } consistent with the downward trend (Table 7) noted by Lawton et al. (1985). l Dominant species were pollock (Pollachius virens) and cunner (Tautogolabrus l l adspersus), together totaling 66.2% of the overall catch. This compares J f well with totals of 61% (1985), 58% (1984), and 59% (1983) reported for these two species over the last three years. Together with Atlantic herring (Clupea 8 40
. - - - . . . ~ . , , , . - - - - - . -. - . - . - , . - . , _ . , , . - - . - . - - , - . .~ . . - , - . , , - -.. , , . - . - - . >
Windowpane Winter l Spring l Summer Tl Fall 25.1 26.8 T
#*9 12 - "' -
11 _ _ 10 ~ Station Key ,"' ~ 9~ 1. Warren Cove
~
- 3. Discharge
- 4. White Horse --
8- 6. Intake "
@ 7-x .. $ 6- -
5' n -
- 4. _
i- . 3 -. p -
. e.e -
1, , - . - :: 55 , a, 11 I I I o 1 3 4 6 13 46 1 34 6 1 3 4 6 Station Station Station Station Figure 13. Seasonal mean trawl catch rates with vertical error bars for windospane by station in Pilgrim area, 1986. 41
Table 6 Number, percentage composition, and size range of finfish-species captured by gillnet (7 panels of 3.8-15.2 cm mesh) in the vicinity of Pilgrim Nuclear Power Station, January-December, 1986. Percent of Size 1 Species Number total catch range (mm) l Pollock 799 50.7 145'- 392'FL Cunner 244 15.5 111 - 293 TL I Atlantic herring 130 . 8.3 155 - 285 FL ; Tautog 89 5.6 164 - 530 TL Silver hake 63 4.0 215 - 415 FL Alewife 38 2.4 134 - 293 FL Atlantic menhaden 38 2.4 215 - 310 FL Bluefish 27~ 1.7 152 - 800 FL ; - Smooth dogfish 27 1.7 543 -1110 TL' ' Northern sea robin 23 1.5 251 - 340 TL Rainbow smelt 22 1.4 190 - 240 TL Scup 13 0.8 174 - 249 FL' l Longhorn sculpin 12 0.8 240 - 315 TL Sea raven 10 0.6 158 - 444 TL Striped bass 10 0.6 307 - 569 FL Hickory shad 7 0.4 320 - 350 FL Winter flounder 7 0.4 271 - 366 TL Atlantic tomcod 5 0.3 175 - 265 TL Atlantic cod 3 0.2 255 - 480 TL Little skate .2 0.1 460 - 496 TL Spiny dogfish 2 0.1 920~-1005 TL Atlantic mackerel 1 0.1 406 FL I Blueback herring 1 0.1 *not measured Goosefish 1 0.1 *not measured Rock gunnel 1 0.1 128 TL Winter skate 1 0.1 496 TL Total 26 species 1,576 FL = Fork Length TL = Total Length
- i i
- 42 i
i e i e
. ~ - , . . . . - - -- -
., _ _ _ . _ _ . ..-m.-, ,.--.%.. - , ,,.._r _ - - . , --,v. -,-w-
- a harangus harennus), which ranked third in 1986, these species have consistently dominated the catch records since 1971 with the exception of 1985, when'the relative abundance of Atlantic herring inexplicably declined.
Pollock Comprising 50.7% of the total gill net catch, pollock were captured from April to December at bottom temperatures ranging from 6.0 to 18.0 C. Pollock were as abundant in the summer (46.4%) as in the spring (44.5%). CPUE of pollock for spring and summer was 25.4 and 26.5, respectively. Annual mean e CPUE (Table 7) for this species in 1986 (50.0) was essentially the same as in 1985 (48.2), suggesting no change in local stock size. Cunner Cunner ranked second in overall gill-net catch comprising 15.5% of the total (Table 6). As in 1985, cunner were first netted in April (bottom water temperature of 8.5 C), with the majority (76.3%) captured during the By late fall (December), summer months (bottom temperature of 15.5-18.0 C). bottom temperatures dropped to 6.0 C, and cunner had all but disappeared (1 fish caught) from the study area. Olla et al. (1975) noted, that at water temperatures of 5-6 C and below, cunner move offshore to deeper water and become inactive, moving inshore when water temperatures rise in the spring. Relative abundance in 1986 (16.9), as estimated by the annual mean catch-per-set, was essentially unchanged from 1985 (16.3). T.his may represent a
" leveling off" of an apparent decline in abundance noted by Lawton et al.
(1986) for the Pilgrim area in 1985. Atlantic herring Nearly absent from 1985 gill-net catches (5 fish), Atlantic herring was the third most abundant species (8.3%) netted in 1986 and were caught 3
. 43 .
only in late winter /early spring and late fall. Lawton et al. (1986) reported that relative abundance of Atlantic herring in the Pilgrim Station area has varied greatly since the inception of the gill net study; evidence for this finding can be found in Table 7. Further, Bigelow and Schroeder (1953) reported that great fluctuations in local abundance are common for this species through-out the entire Gulf of Maine area. Tautog A common inhabitant of the rocky inshore waters of Cape Cod Bay (Bigelow and Schroeder 1953), tautog (Tautoga onitis) was fourth in catch, abundance l (5.6%). We noted (Lawton et al.1986) that for the last four years, tautog , in the Pilgrim area appeared to be at a stable population level. A relative i 1 abundance index of 4.4 in 1986 (Table 7) is consistent with relative abun- ! dance estimates of the past four years. Tautog were collected from April to October at bottom water temperatures that ranged from 8.5-14 C. The highest monthly catch was in September when 36 individuals were netted. Other species The remaining species captured by gill net were taken in relatively low numbers, with no single species comprising more than 4% of the total catch. The majority have been captured only sporadically and hav'e never occupied positions of dominance in gill-net records. The Atlantic cod (Gadus morhua) has experienced an overall decline for several years (Lawton et al.1986) . Striped bass (Morone saxatilis) and bluefish (Pomatomus saltatrix) have demonstrated affinities for the thermal effluent at Pilgrim Station (Lawton et al. 1985); they were not netted in any numbers during the outage year of 1984. 44
Table 7. Indices of relative abundance (catch-per-unit-effort) for selected and pooled finfish species captured in western Cape Cod Bay near Pilgrim Nuclear Power Station based on standardized gill-net gear (5 panels of 3.8 - 8.9 cm mesh) and procedures, 1971-1986. Species Years 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 Pollock 67.9 119.8 109.1 41.6 22.1 57.2 141.8 91.3 86.9 135.2 110.7 54.8 76.7 53.8 48.2 50.0 Atlantic cod 8.9 14.2 9.6 7.9 6.1 4.4 3.0 2.8 6.5 4.5 4.1 8.9 6.0 3.1' l.7 0.1 Silver hake 0.3 0.1 0.4 8.4 5.1 21.8 13.4- 0.0 0.0 2.5 0.7 2.3 2.3 4.3 1.4 4.4 Cunner 18.9 18.6 '21.1 18.9 26.4 27.6 42.7 44.0 38.6 44.3 40.7 38.8 35.5 27.1 16.3 16.9 Tautog 0.7 0.6 1.2 1.0 0.4 1.2 0.6 0.7 3.1 1.9 1.6 4.4 5.1 5.2 5.7 4.4 g Alewife 44.3 10.8 15.3 29.6 4.1 12.2 7.4 14.5 4.7 6.1 1.3 3.0 ' 9.7 3.1 .2.0 2.6 Atlantic herring 14.2 1.5 . 4.6 19.9 17.4 96.1 80.0 22.3 56.0 14.7 -44.4 13.3 17.8 14.2 0.4 9.0 Atlantic menhaden 1.8 0.7 1.9 4.9 4.1 6.4 2.7 6.4 8.1 0.5 '1.8 1.9 1.5 0.6 1.3 2.1'- Pooled finfish species 158.7 144.2. 165.5 140.9 96.8 229.0 296.4 202.1 232.5 231.8 224.7 150.5 151.6 135.3 118.8 99.6 e I
- - - - - - - - ~ --
1 In summation, overall relative abundance for' dominant species either equaled or slightly exceeded 1985 values (Table 7). Mean CPUE for pooled species, however, was down from last year; the annual mean of 99.6 was similar to the 96.8 fish per set reported for 1975, which_was the lowest index pre-viously recorded (Table 7). i
- 5. SHORE-ZONE FISHES l
A total of 9.272 finfish representing 26 species was captured in 85 sets i of the haul seine completed during 12 sampling days from May-October, 1986 (Table 8). Invertebrates also caught were the common shrimp (Cranson spp.), green crab (Carcinus maenas) and unidentified amphipods, isopods, and cteno-phores. Water temperature and salinity throughout the sampling regime ranged
; from 9.5 to 21.0 C and 29 to 34 */... respectively.
The annual index of total finfish catch (i.e., catch of finfish per
! standard seine set) for all stations and species pooled declined 79% from 1985. Decreased catches of schooling species, namely Atlantic silverside (Menidia menidia), blueback herring (Alosa aestivalis), alewife (Alosa pseudo-harengus), and sand lance (Ammodytes spp.) contributed greatly to the decline t
l in the overall index of catch. Station catch rates declined at all sites, l I with the greatest decreases occurring at Warren Cove (.96%) and Manomet-Point (-81%). Seine catches were highest in the Pilgrim Intake embayment, where 46% i of the total was obtained (Table 8). Overall annual catches were low at Manomet Point and Warren Cove with each contributing 7% and 8% of the total I catch, respectively. It is noteworthy that, in terms of total fish caught, ) i t Pilgrim Station was more similar to Long Point, an estuarine location, than l to the exposed coastal beach stations, Warren Cove and Manomet Point. 4 ! 46 i )
Table 8. Shore-sone fishes captured by haul seine at -four stations
'in the vicinity of Pilgrim Nuclear Power Station.
Tay-October, 1986. Station 2 3 5 6 Warren- Pilgrim Lor.g Manomet' Total Percent of Sp ci s Cove Intakel Point Point Number total catch
- 3. . .1::4!::1.3 Atlantic silverside 517 !!!!!:!![5$i!!!!!$ 2369 505 3646 39.3 Blueback herring 42 ji)$31!!:!!!!b 343 14 2221 24.0 Ernd lance opp.* 0 47 0 1421 15.3 Atlantic menhaden 114 {1574?:l!h
'!!!!4N!!! 44 0 786 8.5 t! int:r flounder 10 ?!!:tMi!!!$ 103 19 308 3.3 Windowpane' '*
30 t !!!Mi! x 88 54 218 2.4 Ntrth:rn pipefish 2 ejg 157 29 200 2.2 Rainbow smelt 1 ss833li!!!
" ~
e0 1 125 1.3 Cunn:r 0 ' :Mjs 84 0 88 0.9 L:ngh;rn sculpin 0 i!!!ni!!jj 56 0 58 0.6 Hummichog 3 l!!1!!! - 54 0 57 0.6 Atlatic- toscod 1 !! !!!j)!!!:tj 33 0 37 0.4 Striped killifish 6 [:!(.).j ii!$F'I 22 1 29 0.3 N1rthern puffer 8 *ist 1 1 29 0.3 B:y (nchovy 3 fll[1$ 0 0 13 - Lumpfish 0 s !?t$ 1 0 11 At10atic see herring 5 '!!!A!!!!!g 2 0 to Thrr.cpine stickleback 0 F li[2!!!!!!!( 1 1 4 Rock gunnel 0 G 3 0 3 Alevife 1
$ j!;#jif.;
i;i! jiii:!! 0 1 2 Tcutig 0 !!!4!!!!!ll -1 0 1 Grubby O s li!)i!!.] 1 0 1 Ys11:vtail flounder 0 s llifj 1 0 1 = 0.5 4 Nsrth rn kingfish 1 !@;6:!:jjjjj
- J. 0 0 1 Whits hake 0 0 0 1 Initnd silverside 0 liil!!!!!!!{
ijjjj!!!s.,. 0 0 1 s
-=5$$
Tctal number of fish 742 (48$jj!!ll 3611 626 9272 Nu;bst of sets 24 ltiii.lllljjjhj!h 24 - 18 85 s. Catch / set 30.9 l5llfAANk 150.5 34.8 109.1 1 4 Tats 1 number of species 15 , lN!! ' s: - 20 10 26 V.- - Pare:nt of total catch ' 8.0 Ec,. . (. .' :.);.:.: .!l[464 38.9 6.8 ANat caparated by species 1 45.7 m x 3.0 m seine Shrd:d column is data from surveillance station. 1 l I l l l 47 1
Five taxa - Atlantic silverside, blueback herring, sand lance spp., Atlantic menhaden (Brevoortia tyrannus), and winter flounder (Pseudopleuronectes americanus) - comprised 90% of the overall catch. For the sixth consecutive year, the Atlantic silverside was the most abundant species, accounting for 39% of the fish seined in 1986.' With the exception of the Intake station, silversides dominated seine sets in both catch-per-unit-effort and percent frequency of occurrence (Table 9). Catch rates for Atlantic silverside declined, however, throughout the stddy area from 1985, with the greatest decrease occurring in Warren Cove. Blueback herring comprised 24% of the total seine catch and were captured at all stations. This species ranked second in numerical dominance but fifth i in frequency of occurrence. This reflects the aggregated distribution pattern of bluebacks, which in turn, affects their availability to capture by seining. At times, large catches have been recorded. Ranked third in overall catch, sand lance spp. were primarily caught in the Intake. The mean catch rate of sand lance in the study area declined 85% from 1985, while percent frequency of occurrence remained comparable. Atlantic menhaden and winter flounder comprised 8.5% and 3.3%, respec-tively, of the total catch. Menhaden ranked fourth in the hierarchy of catch, but seventh in frequency of occurrence. Most of the menhaden were captured in two seine hauls at the Intake station. Winter flounder, which were I sampled at all stations, ranked fifth in catch, but second (all stations l pooled) in percent frequency of occurrence (Table 9). The catch rate for I winter flounder was highest at Pilgrim Intake, where this species ranked first in percent frequency of occurrence of catch. l Seasonally, seine catches were highest in late summer /early fall, with the monthly mean catch index for all stations and species pooled peaking in f 48
l Table 9. Perc'ent frequency of occurrence of selected shore-zone fishes sampled at four haul-seine stations in the vicinity of Pilgrim Nuclear Power Station, May-October, 1986. Stations 1 Warren' Pilgrim Long Manomet All Stations Species Cove Intakel Point Point Pooled Atlantic silverside 58.3 (!N..,s
?
dis$ 83.3 44.4 58.8 Winter flounder 16.7 [illlfi[yll 62.5 27.7 44.7 Windowpane 33.3 QMK4lll! 45.8 22.2 37.6 Blueback herring 29.2 g!!!l$$jj 16.7 11.1 23.5 Northern pipefish 4.2 jjjl26{3pj 50.0 11.1 23.5 Sand lance app.* 0.0 liif 4.2 0.0 10.6 Atlantic menhaden 8.3 fi)p2Mj!!3 0{3] 4.2 0.0 5.9 Rainbow smelt 4.2 gijiq3{$!!!j 0.0 5.6 5.9 ANot separated by species 1 45.7 m x 3.0 m seine Shaded column is data from surveillance station. l 49 1 2
August. This seasonal trend has occurred each year of our seine study begin-ning in 1981. Annual species diversity, as measured by the total number of species caught at a station, was highest at Long Point (20 species) and lowest at Manomet Point (10 species). Pilgrim Intake most resembled Long Point in terms of both total number of species (Table 8) and mean number of species caught per seine haul (Table 10). Of the 26 species seined (all stations: pooled), six: Atlantic silverside, blueback herring, winter flounder, windowpane (Scophthal-mus aquosus), northern pipefish (Syngnathus fuscus), and northern puffer (Sphoeroides maculatus) were taken at all stations, and comprised 72% of the total catch. In contrast, seven species were taken only at one station and comprised 0.1% of the total catch. A comparison of the numbar of shared species between stations revealed that Pilgrim Intake most resembled Long Point (14 shared species) and was least similar to Manomet Point (8 species in common) . Warren Cove shared 11 species with both Long Point and Pilgrim Intake, and 9 species with Manomet Point. 1 In summation, Pilgrim Intake was similar to Long Point in total catch, I species number, species number per seine haul, and number of shared species. These two stations shr.re two characteristics which may account for the simi-larities in abundance and diversity: both are semi-enclosed embayments , which offer protection from heavy surf, and both possess a good amount of vegetation which provides suitable habitat for small fishes. This contrasts with the exposed coastal stations, Warren Cove and Manomet Point, which have little cover and are subjected to heavy surf. Species diversity and abun-dance were lower at these stations than at either Pilgrim Intake or Long Point. ! 50
Table 10. Monthly mean number of species per haul seine set for four stations sampled in the vicinity of Pilgrim
-Nuclear Power Station, May-October, 1986.
Station 2 3
- Warren ' Pilgrim Long- Manomet I Month Cove - Intakel Point Point p .
r#, May 0.5 q 1.0 0.2
-June 0.8 W 2.0 0.0 July 2.0 [' l 3.5 2.0 t August 3.2 n f~ 7.0 3.5 September 3.0 !!!!! 8.0 2.0 October 3.2 Wi!! .
$ _6.0 2.5 I 45.7 m x 3.0 m seine t
f Shaded column is data from surveillance station. i i I i i r i i i l l i l I 51
- 6. UNDERWATER FINFISH OBSERVATIONS The 1986 observational diving study began early May, with a total of 14 dives made through late Octcber. Over 1,500 fish, comprising 8 species (Table 11) were observed in the study area (Figure 5) . Invertebrates noted
~
included horseshoe crab (Limulus polyphemus), blue mussels (Mytilus edulis), starfish (Asterias spp.), lobster (Homarus americanus), and rock crabs (Cancer irroratus and C. borealis). To aid the benthic monitoring program, project personnel also recorded qualitative observations of Irish moss (Chondrus crispus) growth and distribution along a transect used by the Battelle researchers in the discharge area. Estimates of visibility in the water column (obtained through use of a i secchi disk and metered line) ranged from 0.5-14 m (average 7 m), depending on incident light and sea condition. The average visibility during 1985, a year of high operational output, was estimated at 2.5 m. Undoubtedly, enhanced water clarity in 1986 resulted from the plant outage and attendant reduction in discharge current. The total fish sighted in 1986 approximated the level (1105 fish) in 1985. As in 1985, the majority of fish (64.3%) were noted in the discharge zone (D), whereas, 31% were sighted in the control zone (C) and only 4.6% in the stunted area (S). The finfish species most often seen by project divers was the cunner (Tautogolabrus adspersus) . Comprising 79.5% of all sightings (Table 11), cunner were most abundant at Station D , in the discharge zone and were found 2 at all stations in the study area. The number observed, 1,229, represents an increase over 1985 (714); however, poorer visibility during the 1985 study may have influenced the number sighted that year. Supporting evidence is 52
3 Table IL Abundance and size ranges associated with the occurrence of all species observed during underwater observations,
- May-October, 1986.
2 Number Station- Size observed' % of where most range Species- by divers total. abundant TL (cm) m 2 - 20 Cunner 1,229 79.5 D 2 Tcutog 170 11.0 D a 10 - 41 2 Pollock 130 8.4 C a 10 - 20 2 Striped bass 10 0.6 D 25 - 41 2 i Atlantic silverside 2 0.1 D 2 28 Rtck gunnel 2 0.1 Cg+C2 a - 8 Ssa Raven 1 0.1 D a 23 , 3 Winter flounder 1 0.1 Dg a8 l l r i i t i 2 53 , i l l l
.~ . - .. . .. . .
4 . J
< provided from our 1986 gill-net records, which indicate'the cunner catch. rate l
} to be approximately the same as in 1985. 1 ! Found primarily in the discharge zone (91% of all sightings), tautog (Tautoga onitis) was the second most abundant species observed (Table 11). - About 170 tautog were counted wh'ich represents a 26% decrease from 1985 records (230 fish). A decline'was not noted in our 1986 gill-net catches. As in 1985, tautog in the discharge area were often seen moving'into and out of the mouth of the discharge canal. { Pollock (Pollachius virens) ranked third in number of fish sighted (Table 11). { As noted in the past (Lawton et al.1985), pollock were generally sighted in small aggregates and only rarely as single individuals. Nearly absent from I diving records in 1985 (8 fish), the sighting of 130 pollock in 1986 suggested
, a renewed abundance in the observatior.al area.
Striped bass (Morone saxatilis) were seldom sighted in the observational area and were scarce throughout the Pilgrim Station area as a whole as evidenced
- l by low gill-net and sportfish catches. This situation is similar to that noted during the outage year of 1984, when no bass were observed by project
- divers.
Comprising less than 1% of the total sightings (Table 11), the remaining j four species were represented by only one or two inditiduals. 4 7. SPORTFISHING ! l [ During the 1986 creal survey period. April-November, reportedly less than 2,000 angler trips were made to the Shorefront and seven species of fish caught. Of the total catch (approximately 500 fish), cunner (Tautogolabrus adspersus) - i I 54 i
l 48%, winter flounder (Pseudopleuronectes americanus) - 32%, and bluefish (Pomatomus saltatrix)- 11% together comprised 91% while tautog (Tautoga onitis), pollock (Pollachius virens) and skate app. (Raja spp.) accounted for the other 9% of the catch. Fishing occurred from the two discharge jetties, the outer intake break-water, and the head of the intake embayment. Still-fishing with natural bait was by far the most popular fishing method from the breakwater. Casting artificial lureswas the predominant technique from the discharge jetties. Ranging in age from 15-72, fishermen sought bluefish, winter flounder, and ctriped bass, in that order. More anglers came from Plymouth and the sur-rounding towns of Kingston and Manomet than any other location. Fishing pressure increased in the spring, peaked July-August, and declined through November. Over 50 percent of the angling trips occurred during the former two months. This seasonal distribution of fishing activity was similar to findings for comprehensive surveys conducted there in the past (Lawton et cl. 1984). Favorable weather conditions and the traditional summer vacation period were contributing factors to the seasonal pattern of effort. Highest catches (pooled species) were recorded in July and August. Cunner led all catches and was angled June-September, with peak fishing in August. Winter flounder ranked second in sportfish catch and were caught May-November. The highest landing was in October. Taken June-October, blue-fish were most frequently caught in August. Overall, catches were low relative to records from past years. 55
V. ACKNOWLEDGEMENTS We acknowledge the contributions of the numerous staff members of the Massachusetts Division of Marine Fisheries who assisted in phases of field sampling, especially Neil Churchill, Joseph O'Gorman, and summer intern Gary
~
Nelson; and of Leigh Bridges in editing the final manuscript. We thank i John Karbott and Chris Kyranos for allowing us to sample their lobster pot catches; and W. C. Sibley and Richard Schneider for overseeing the collection of creel data at the Shorefront area. Also, greatly appreciated is the work of Carleen Mackin for typing this report. Finally, we thank Robert. D. Anderson and the Pilgrim Advisory-Technical Committee for overseeing the entire study I program. ; I l 56
LITERATURE CITED Aiken, D. E. and S. L. Waddy. 1982. Cement gland development, ovary matura-tion, and reproductive cycles in the American lobster Homarus americanus. Jrl. 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. Boston Edison Company. 1980. Benthic map overlays and assessment of benthic monitoring programs, Vol. 2. Nuclear Engineering Dept., Environmental Sciences Group. Boston Edison Company, Boston, MA, USA. 25 pp. Bridges. W. L. and R. D. Anderson. 1984. A brief survey of Pilgrim Nuclear Power Plant effects upon the marine aquatic environment, p. 263-271. In: 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. 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. Cobb, J. S. 1971. The shelter-related behavior of the lobster, Homarus americanus. Ecology 52: 108-115. Conover, D. O. and M. R. Ross. 1982. Patterns in seasonal abundance, growth, and biomass of the Atlantic silverside, Menidia menidia, in a New England estuary. Estuaries 5(4): 275-286. Doret, S. C., D. R. F. Harleman, A. T. Ippen, and B. R. Pearce. 1973. Charac-teristics of condenser water discharge on the sea surface. R. M. Parsons Laboratory for Water Resources and Hydrodynamics. Dept. of Civil Engineering, Massachusetts Institute of Technology, Boston, FM, USA. 156 pp. Estrella, B. T. and D. J. McKiernan. 1986. Massachusetts coastal commercial lobster trap sampling program, May-Nov. 1985. Mass. Dept. of Fisheries, Wildlife, and Environmental Law Enforcement, Division of Marine Fisheries. 74 pp. Fair, J. J., Jr. 1977. Lobster investigations in management area 1: southern Gulf of Maine. NOAA, National Marine Fisheries Service Division. Report No. 8. Massachusetts Div. of Marine Fisheries. Howe, A. B., T. P. Currier, S. L. Sass and B. C. Kelly. 1985. Coastwide Fishery Resource Assessment. Massachusetts Division of Marine Fisheries, 35 pp. 57 I l l l 1 ____.m . _ _ _ _ . _ .- _ _ _ . _
Krouse, J. S. 1973. Maturity, sex ratio, and size composition of the natural population of the American lobster, Homarus americanus, along the Maine coast. Fishery Bulletin 71(1): 165-173. Krouse, J. S. and J. C. Thomas. 1975. Effects of trap selectivity and some population parameters on size composition of the American lobster, Homarus americanus, catch along the Maine coast. Fishery Bulletin 73: 862-871. Lawton, R. P., P. Brady, C. Shee'han, W. Sides, E. Kouloheras M. Borgatti, and V. Malkoski. 1984a. Growth and movement of tagged lobsters released in western Cape Cod Bay, 1970-1977, p. 119-129. In: J. D. Davis and D. Merriman (editors), Observations on the ecology and biology of western Cape Cod Bay, Mass. Springer-Verlag. Verlin, FRG. 289 pp. Lawton, R. P., P. Brady, C. Sheehan, W. Sides, E. Kouloheras, M. Borgatti, and V. Malkoski. 1984b. The recreational fishery at Pilgrim Shorefront,
- p. 231-240. Irt: 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.
Lawton, R. P., C. Sheehan, V. Malkoski, S. Correia, and M. Borgatti. 1985. Annual report on montioring to assess impact of Pilgrim Nuclear Power Station on marine fisheries resources of western Cape Cod Bay. Project Report No. 38 (January-December, 1984). IIg Marine Ecology Studies Related to Operation of Pilgrim Station, Semi-Annual Report No. 25. Boston Edison Company, Braintree, MA, USA. Lawton, R. P., V. J. Malkoski, S. J. Correia, J. B. O'Gorman, and M. R. Borgatti. 4 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). Igg Marine Ecology Studies Related to Operation of Pilgrim Station. Semi-Annual Report No. 27. Boston Edison Company, Braintree, MA. Olla, B. L., A. J. Bejda, and A. D. Martin. 1975. Activity, movement, and feeding behavior of the cunner, Tautogolabrus adspersus, and comparison i of food habits;. with young tautog, Tautoga antein, off Long Island, New York. Fishery Bulletin 73: 895-898, t i i i 58 i
s Appendix A Average legal lobster (carapace length 2 81 ma and non-ovigerous) catch per pot haul per month for all quadrats combined for years 1970-1986. Seasonal March April May June July Aug Sept Oct Nov Mean 1970 - - 0.41 0.30 0.54 0.75 0.61 0.68 0.80 0.58 (330) (351) (627) (667) (571) (691) ( 72) 1971 0.68 0.46 0.62 0.32 0.68 0.86 0.77 0.70 - 0.64 ( 95) (331) (681) (591) (723) (730) (668) (668) 1972 - 0.59 0.55 0.31 0.66 0.80 1.30 0.88 - 0.73 (428) (24'J) (519) (718) (707) (477) (352) 1973 - 0.46 0.39 0.41 0.74 0.60 0.56 0.82 - 0.57 (135) (646) (634) (625) (295) (279) (151) 1974 - - 0.38 0.33 1.00 0.51 1.09 0.64 - 0.66 (309) (341) (544) (595) (499) (455) 1975 - 0.32 0.23 0.26 0.64 0.58 0.81 0.70 0.65 0.52 (322) (525) (555) (314) (299) (278) (269) (233) 1976 - - 0.27 0.21 0.69 0.59 0.34 1.11 0.63 0.55 (438) (541) (641) (544) (570) ( 37) (178) 1977 - 0.48 0.46 0.29 0.55 0.47 0.72 0.86 - 0.55 (379) (417) (203) (555) (663) (604) (664) 1978 - - 0.41 0.30 0.63 0.62 1.09 0.71 - 0.63 (374) (571) (441) (600) (279) (162) 1979 - - 0.31 0.29 0.54 0.59 0.50 0.42 0.58 0.46 (130) (659) (797) (491) (200) (272) (271) 1980 - - 0.21 0.25 0.63 0.64 0.58 0.84 0.63 0.54 (107) (477) (983) (849) (476) (520) (255) 1981 - - 0.58 0.26 0.62 0.64 0.96 0.73 0.67 0.64 (319) (798) (744) (352) (696) (482) (377) 1982 - - 0.45 0.46 0.46 0.73 1.11 0.66 0.58 0.64 (410) (271) (780) (877) (475) (454) (107) 1983 - - 0.18 0.23 0.90 0.96 0.78 0.59 - 0.61 (719) (486) (805) (573) (506) (420) 1984 - - 0.29 0.29 0.21 0.54 0.53 0.84 - 0.32 (420) (676) (866) (736) (827) (222) 1985 - - 0.35 0.20 0.57 0.68 0.88 0.77 0.99 0.66 (382) (162) (644) (752) (391) (755) (139) 1986 - 1.01 0.57 0.52 0.43 0.84 1.16 1.07 0.99 0.77 (155) (318) (362) (953) (762) (751) (242) (149) (Number of pots hauled) l 59
- . . ~- .
.. ~ - . .
4 I i i Appendix B f I Total yearly lobster pot catch for years 1970-1986. not oviserous Number and Overall Legal l No. of Total . length gensth % Females catch catch Y*er pots catch Male Female h 81 as _ 81 mm Oviserous per pot per pot 1970 3200 11399 4950 6449 1889 9334 195 3.6 0.60 , (43) (57) (17) (82) 3.0% 1971 4376 15158 6543 8615 2885 12043 2 60 3.5 0.65 (43) (57) (19) (79) 3.0% 1972 3449 13527 5484 7051 2522 9844 166 3.6 0.73 (43) (56) (20) (79) 2.4% 1973 2762 7821 3456 4363 1490- 6267 68 2.8 0.54 (44) (56) (19) (80) 1.6% 1974 2743 8386 3838 4558 1922 5426 41 3.0 0.70 (46) (54) (23) (77) 0.9% 1975 2795 8210 3757 4443 1306 5884 20 3.0 0.47 (46) (54) (16) (84) 0.4% 1976 1959 9179 4308 4871 1352 7819 8 3.1 0.46 (47) (53) (15) (85) 0.2% 1977 3485 7694 3846 4078 2050 5596 27 2.2 0.59
; (47) (53) (27) (73) 0.7%
1978 2602 7717 3432 4285 1535 6147 35 3.2 0.63 (44) (56) (20) (80) 0.8% 1979 2820 5596 2339 3257 1325 4214 57 2.0 0.47 (42) (58) (24) (75) 1.8% i 1980 3667 7534 2892 4642 2181 5244 109 2.1 0.59 4 (38) (62) (29) (70) 2.4% i I 1981 3767 8294 3260 5034 2347 5756 191 2.2 0.62 j (39) (61) (28) (69) 3.8% 1 ! 1982 3374 7794 2899 4895 2195 5457 142 2.3 0.65 I (37) (63) (28) (70) ' 2.9% I' 1983 3509 6751 2539 4212 2156 4461 134 1.9 0.61 I (38) (62) (32) (66) 3.2% 1984 3747 4664 1696 2968 1515 3070 79 1.2 0.32 (36) (64) (32) (66) 2.7% 1985 3225 6407 2512 3985 2119 4190 98 2.0 0.66 (39) (61) (33) (65) 2.5% 1986 3692 8103* 3360 4725 2852 5166 85 2.2 0.77 I-(42) (58) (35) (64) 1.8% ! (Parcent of total catch) 1 i e18 lobsters were not sexed. i 60 l 1 I l
ANNUAL REPORT ON MONITORING TO ASSESS IMPACT OF PILGRIM NUCLEAR POWER STATION ON MARINE FISHERIES RESOURCES OF WESTERN CAPE COD BAY (IMPACT ON FISHERIES RESOURCES) Project Report No. 42 (January-December, 1986) Summary Report No. 19 (Volume 2 of 2) By i Robert P. Lawton, Vincent J. Malkoski, Steven J. Correia,
. Brian C. Kelly, Mando Borgatti, and Buell Hollister April 15, 1986 I
Massachusetts Department.of Fisheries, Wildlife, and Environmental Law Enforcement Division of Marine Fisheries ' 100 Cambridge Street Boston, Massachusetts 02202 i
- 1 l
l i
1 TABLE OF CONTENTS Section- P,,, age, l
'I. EXECUTIVE
SUMMARY
II. INTRODUCTION 6 < III. RESULTS AND DISCUSSION 7 ! . A. -Igact of Pilgrim Station on Fisheries Resources 7 l
- l. Commercial Lobster Pot-Catch Fishery 7'
'2. Research Lobster Trap Fishing 10 ;
- 3. Nearshore Benthic Finfish 21
- 4. Pelagic and Benthi-Pelagic Fishes 33
- 5. Fishes of the Shore Zone 44
- 6. Underwater Finfish Observations 48 i
.7. Sportfishing 60 B. Impact Perspective 61-i V. ACKNOWLEDGEMENTS 64
.j VI. LITERATURE CITED 65 VII. APPENDIX 67 ) i a l l T t i I ll
~
I l LIST OF TABLES t Trble g 1
- 1. Catch per unit effort from experimental fishing for American lobster 12 ;
in the Pilgrim area for 1986. l
- 2. Kolmogorov-Smirnov test of s'ize distributions (all lobster, sublegals, 20 l legals) of lobster captured at sampling locations in the Pilgrim area by experimental trap fishing, 1986.
- 3. Significance of differences between station seasonal trawl catch rates 26 of little skate in the Pilgrim area, 1986, e
- 4. Significance of differences between station seasonal trawl catch rates 28 of windowpane in the Pilgrim area, 1986.
- 5. Significance of differences between station seasonal trawl catch rates 30 of winter flounder in the Pilgrim area, 1986. .
- 6. Mean catch per standard gill net (5 panels of 3.8-8.9 cm mesh) set 35 (CPUE) for various time periods and the percent differences for selected species caught in the vicinity of Pilgrim Station, 1971-1986.
- 7. Mean catch per standard seine set for selected species collected along 47 the Plymouth shoreline, western Cape Cod Bay, 1983-1986.
- 8. Indices of relative abundance (fish / dive) for two specios observed by 52 divers in the Pilgrim Nuclear Power Station Discharge canal, 1981-1986.
- 9. A summary of impact assessment by study of Pilgrim Nuclear Power . 62 Station (PNPS) on marine fisheries resources in western Cape Cod Bay during the operational history of the power plant.
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.a LIST OF FIGURES Figure Page, ,
- 1. Lobster pot sampling grid for lobstermen monitored along the Pilgrim 8 shoreline. (Surveillance (H-11, H-12, 1-11 and I-12) and reference 4 (E-13. E-14, and F-13) quadrats are shaded.]
.i i l 2. Location' of experimental lobste'r gear (5-pot trawls) for Marine Fisheries 13 * ' studies. The surveillance area includes Stations A-D; the reference areas ' include Stations E and F off Rocky Point and Stations G and H off White l Horse Beach. 4 j 3. Summer size distribution of lobster captured in experimental trap hauls 16 - l in the surveillance area off . Pilgrim Station,1986. Legal-sized lobster i are 2 81 mm CL; sublegal < 81 mm CL; Y, mean carapace length, i 4. Summer size distribution of lobster captured in experimental trap hauls 17 l st all reference stations pooled off Pilgrim Station,1986. Legal, 2 81 mm CL; sublegal, < 81 mm CL; Y, mean length.
~
I 5. Summer size distribution of lobster captured in experimental trap hauls. 18 at the Rocky Point reference area, north of Pilgrim Station,1986. Legal, 2 81 mm CL;~sublegal, < 81 mm CL; x, mean length.' i
- 6. Summer size distribution of lobster captured in experimental trap hauls 19 i at the White Horse reference area, south of Pilgrim Station,1986. Legal,'
i 2 81 mm CL; sublegal, < 81 mm CL; Y, mean length. 1
- 7. Mean annual catch per standardized tow of'three dominant groundfish by 23 bottom trawl at reference Station 1 and surveillance Station 3, 1982-1986.
- 8. Seasonal mean trawl catch rates with vertical error bars for little skate 25 by station in Pilgrim Station area, 1986.-
i i 9 Seasonal mean trawl catch rates with vertical error bars for windowpane- 27 by station in Pilgrim Station area', 1986.
- 10. Seasonal mean trawl catch rates with vertical error bars for winter 29 flounder by station in Pilgrim Station area, 1986.
I 11. Percent relative frequencies of winter flounder lengths (grouped in 2 cm 32 l- intervals) by station for trawl data collected in Pilgrim Station area, 1 July-September, 1986.
- 12. Mean annual gill-net catch-per-unit-effort for-pollock in the vicinity 34 of Pilgrim Station and annual Unit I Capacity Factor (MDC Net %) 1971-1986.
l-
- 13. Mean annual gill-net catch-per-unit-effort for cunner in the vicinity of 34 Pilgrim Station and Seasonal Unit I Capacity Factor (MDC Net %) 1971-1986.
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( d iFigura P_ age ! 14. Mean gill-net catch-per-unit-effort for Atlantic herring ar.J yearly 39
' Unit I Capacity Factor (MDC Net %) at Pilgrim Station, 1971-1986.
- - 15. Mean gill-net catch-per-unit-effort for tautog in the vicinity of Pilgrim 39 Station and seasonal Unit I Capacity Factor (NDC Net %), 1971-1986.
42
' 16. 'Mean annual gill-net catch-per-unit-effort for alewife in the vicinity of Pilgrim Station and seasonal Unit I Capacity Factor (MDC Net %),
! 1971-1986. ['17. Mean annual' gill-net catch-per-unit-effort for Atlantic cod and annual 14 2 ' l Unit I Capacity Factor (MDC Net %) at Pilgrim Station, 1971-1986.
- 18. Finfish observational diving stations at PNPS discharge.
- 19. Distribution of cunner for each observation station:and zone-off the 51 f
Pilgrim Station discharge canal, May-October, 1984 and 1986. l 20. Distribution of cunner for each observation station and zone off the 53. l Pilgrim Station discharge canal, May-October, 1983 and 1985. 4
- 21. Distribution of tautog for each observation station and zone off the~ 56 Pilgrim Station discharge canal, May-October,.1983 and 1985.
I 22. Distribution of tautog for each observation station and zone off' the 57 l Pilgrim Station discharge canal, May-October, 1984 and 1986.
- 23. Distribution of pollock for each observation station -and zone off the 58
! Pilgrim Station discharge canal, May-October, 1983 and 1985.
- 24. Distribution of pollock for each observation station and zone off the 59. ,
Pilgrim Station discharge canal, May-October,1984 and 1986. ( i 1 9 v 9 9 9 w -.. -- r-,,9.---,- 9 y r- * ' -'v*- = - - * '- - ' -- - 5-^---N
1 LIST OF PLATES Plate 1. Biologist collecting length-frequency data from the catch of a commercial lobsterman 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 1986 experimental lobster study. This' investigation is designed to better. assess the: ! impact on lobsters of the . thermal effluent at Pilgrim Station.
- Plate 3. Retrieval of the experimental gill net after,a standardized' overnight set in the thermal plume area. Caught in the set is.a smooth dogfish, I a common summer migrant in the Pilgrim area.-
l Plate 4. Fishes caught by gill-net in the erea of the thermal plume at Pilgrim
, Station. Gill-net catches include commercially important species, e.g.,
l Atlantic cod, pollock, 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 benthic' fish community. 4 Plate 6. Typical trawl catch is processed. which includes identifying, enumerating, and measuring the different species for environmental assessment. Catches of winter flounder have been consistently larger at the Pilgrim Station intake trawl station. 1 l Plate 7. Haul seining in the intake embayment 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 potential impact on shorezone fishes.. l Plate 8. Haul seine catch processed on the beach near the Pilgrim Station intake-(fish are enumerated and measured). Among the shorezone fishes are important forage fish such as the Atlantic.silverside and sand lance, l and the juvenile stages of several 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-i fishes in the " denuded" zone directly off the discharge canal. Plate 10. A tautog foraging at the mouth of the discharge canal (Station D) at 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 l i
heated effluent. 1 ! vi i t -
, , . .- .-, . - _ ,,..-- y ..,, . - . , - - .. . _ . _ _ .-,
Plate 11. Pictured is the thermal effluent discharging into Cape Cod Bay and anglers fishing off the discharge jetties and from boats in the plume which is visible in the background by the calm water. Striped bass and bluefish, which are attracted to and concentrate in the thermal current, are the dominant species sought by sport fishermen at this location. Plate 12. Anglers seeking sport (ish at the mouth of the discharge canal. Casting artificial lures is the most popular method of fishing the discharge current which attracts a variety of species. - vii
, 1. EXECUTIVE
SUMMARY
Commercial Lobster Pot!-Catch-Fishery
-. Male lobster -(Homarus americanus) comprised -46% and 42% of the catch in the surveillance and reference areas, respectively. The mean legal-sized catch rates for the reference and surv'eillance areas were comparable, but were lower-than that for the entire study area.
' No statistical differences were found between legal catch rates for the ] curveillance and reference areas for all survey years, the preoperational/ outage years, and operational years. We also found no significant differences batween surveillance and reference legal catch rates paired by year (opera-tional: 1973-1983, 1985).
- A significant negative correlation (P < 0.05) between legal lobster catch T
rate for the surveillance area and annual Pilgrim Station MDC Net % Capacity Factor was found. Conversely,' legal catch rates for the: reference area were , not correlated with thermal output. i Research Lobster Trap Fishing . Experimental lobster trap fishing generated catch data on lobster-popu- } lation parameters: size composition, sex ratios, incidence of culls and barried females, and catch-per-unit-effort. Our 1986 study (late June early
- October) was in effect a uniformity trial conducted during the prestress I
(minimal waste heat) conditions of a plant outage. Based on preliminary trap-ping, the two coastal areas, Rocky Point and White Horse, cannot be pooled for data comparisons with the surveillance area. White Horse differed substan-tially frem Rocky Point and the surveillance area in most of the parameters i examined. However, Rocky Point appears generally to be a good control area to
~
datermine if power plant . induced effects occur in the thermal--discharge. l i i
Nearshore Benthic Finfish
**stion 1 (Warren Cove) . -the primary reference site, was compared with Station 3 (Discharge) in 1986, essentially an outage year. - Mean annual catch rate of winter flounder (Pseudopleuronectes americanus) at Station 3 exceeded that at Station 1 for the first time in the study. However, when' compared with the 1984 outage year, the apparent change in species distribution noted in l
1986 cannot be attributed to reduction in waste heat generation. The 1986 i proportional CPUE's of Stations 3 versus 1 for little skate (Raia erinacea) I and windowpane (Scophthalmus aquosus) also portray no measurable local impact of plant shutdown on these dominant groundfish. Annual station catch rates for-little skate, windowpane, and winter flounder were refined to seasonal levels. Seasonal station CPUE's for each of these dominant groundfish were significantly different in spring and summer, and sometimes in fall. Winter flounder seasonal catch rates at Station 1 (refer-ence) were significantly different than those of all other stations in spring and summer. Winter flounder catch data were further analyzed to ascertain if the intake functioned as a haven for small fish. The Kolmogorov-Smirnov test for differences in length-frequency distributions between two samples was run on spring and summer data; Station 6 (Intake) was compared with every station. Results of this test, and plots of winter flounder seasonal relative length frequencies by station, reveal that the Intake does receive a significant pulse of small winter flounder in summer. Pelagic and Benthi-Pelagic Fish Pollock (Pollachius virens) ranked first in total gill-net catch. The annual relative abundance index has fluctuated throughout the survey years, 2
..#. , # , ..a. -mi .-. - 4-- . ,s6- . .. a d
f 1 g Lbut no relationship between Pilgrim Station operational output and annual CPUE l was apparent. Fluctuations in pollock abundance probably reflect natural vari-I . ability. Cunner (Tautogolabrus adspersus) ranked second in total catch (15.5%). Peoled CPUE for cunner during operational study years 1973-1983, 1985 increased 75% from the preoperational study years. A statistically significant correla-tion-(r = 0.506, P < 0.054) between cunner CPUE'and plant load was found. These results, in conjunction with diving observations, suggest that cunner ware attracted to the thermal effluent .of Pilgrim Station, thereby increasing the probability of nearfield plant impact. 1-Comprising 8.3% of the gill-net catch Atlantic herring (Clupea harengus), f ranked third in catch. The annual relative abundance index has vacillated
^
i -
- throughout the survey years. Catch rate and plant ' load' were not statisti-cally correlated, and no power plant effect has been detected to date. Tautog (Tautoga onitis) ranked fourth in catch. Annual catch rates of tautog fluctu-ated at low levels from 1971-1981, but increased from 1982-1986. It is unclear
- if there is a relationship between thermal capacity and catch rate of tautog.
l l No statistical correlations between CPUE and Pilgrim operational. output were. found for either alewife (Alosa pseudohareneus) or Atlantic cod (Gadus morhua). l Shorezone Fishes i Fishes of the shore zone can potentially be impacted by Pilgrim Station via thermal stress, discharge flow, gas supersaturation, impingement , entrap-ment, and heated backwashes. Our surveys reveal large natural variability in naarshore fish abundances which complicate the measuring of small level effects of power operation. Monthly mean densities of Atlantic silversides (Menidia menidia) seined in the Intake (1981-1986) were not significantly correlated l l l 3 , l rs, c-w,, - , - - - - - - y w+r, ----4 11 v-'- -- m v
[ r L .. I (P > 0.05) with either monthly PNPS thermal capacity or monthly PNPS circulating-i
- pump capacity.
Haul seine data most resemble impingement records. Potential' sources of impinged fishes can be identified via haul seining in the Intake. Of the 26 finfish species impinged from May-October 1986, 13 were seined in the Intake, and a total of 18 at all stations pooled during the same' time period. i' j The Pilgrim Intake Station was similar in species diversity and abundance-indices to the estuarine sampling site at Long Point while the same indices-were markedly lower for the two coastal beach stations. The Pilgrim Intake, with its breakwater and topography, may act as a refuge for shorezone-fishes in an otherwise open coastal region. Underwater-Finfish Observations As noted in the outage year of 1984, algal density in the observational area increased. However, kelp (Laminaria s22,.) was not found in as great i abundance as in 1984. Filamentous brown and green algae were instead the more. common species. Blue mussels (Mytilus edulis) were also more abundant than l 1 l in 1984 and 1985; with the absence of a thermal component in the affluent, mussel growth and proliferation appeared to be limited only by available space and predation. During the outage year of 1984, cunner were observed most often in the control zone. Cunner, the most common species in 1986, was observed most often in the discharge zone, a pattern noted for operational years. . In 1986 no waste heat was produced, but one of the circulating water pumps was in operation, as compared with 1984 when no waste heat and little or no current was released. We believe that cunner are attracted to.the current component 4 4 i e
..-- . - s-- , - - , . - - _ . , - ,- - . , . . . . . ~ . . , . , . - - - . . - - . . - - ,, ,, .--
1 l cf the discharge. Tautog were observed most often in the discharge at Station D I -l 2 however, we believe the primary attraction is food and structure and not temp-grature. Relative abundance of tautog has varied throughout the survey years. Pollock and striped bass sightings were sporadic. The decline in bass sightings is partially attributed to a reduction in thermal discharge due to the outage for most of 1986. Sportfishing Angling activity and sportfish catches at Pilgrim Shorefront in 1986 were among the lowest on record. Two factors contributed to reduced fishing effort and catches: a labor strike closed Pilgrim Shorefront for a portion of the fishing season, and Pilgrim Station released no waste heat and only a limited current into Cape Cod Bay. With the reduction in power level, catches of bluefish (Pomatomus saltatrix) and striped bass (Morone saxatilis) were low, a finding consistent with past trends. The release of heated effluent bene-ficially impacts the shore-based sportfishery in the Rocky Point area, by l l concentrating popular game fish in an ares accessible to anglers. Game fish i attracted to the thermal discharge', however, run a greater risk of impact via ges supersaturation and thermal stress. l l l l l l 5 1 I i i
II. INTRODUCTION Monitoring by the Massachusetts Division of Marine Fisheries is ongoing to assess environmental impact induced by Pilgrim Nuclear Power Station. Ecologi-cal studies of fisheries resources in the surrounding waters of Western Cape Cod Bay for 1986 were funded by' Boston Edison Company under Purchase Order No. 68297. Sampling data collected from reference and surveillance stations during-January-December, 1986, are summarized and discussed in relation to past findings. It is noted that the plant operated consistently during the winter until 7 March, after which outages negated waste heat discharge, and current flow was reduced (one circulating seawater pump was turned off) for the rest of the year. Measurements, counts, percentages, and indices of abundance are used in this report to identify trends and/or relationships in the data both spatially and temporally. Emphasis was placed on comparing data from 1983 and 1985, years of high power plant thermal output ( > 80% capacity), with 1984 (outage year) and 1986 (low output year: 17.5% capacity). Plates 1-12 found on the next several pages- depict samplirg program operations conducted to assess power plant impact on fisheries resources in the western inshore region of Cape Cod Bay. 6
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i Plate 3. Retrieval of the experimental gill net after 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.
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I Plate 4. Fishes caught by gill net in the area of the thermal plume at Pilgrim Station. Gill-net catches include commercially important species,
. e.g., Atlantic cod, pollock, Atlantic mackerel, striped bass, and I
winter flounder.
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l Plate 5. Bottom trawl being set to sample groundfish in the inshore waters of l western Cape Cod Bay. Catches are used to measure potential impacts of Pilgrim Station on the benthic fish community. , s I s .:,
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_s & Plate 6. Typical trawl catch is processed which includes identifying enumerat-ing, and measuring the different species for environmental assessment. Catches of winter flounder have been consistently largest at the Pil-grim Station intake trawl station.
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v. Plate 7. Haul seining in the intake embayment 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 comprehen-sive evaluation of potential impact on shorezone fishes. . . w, . ,.-- . t > N r- 2
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y. l Plate 10. A tautog foraging at the mouth of the discharge canal (Station D) at 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.
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o . - , _ , , Plate 11. Pictured is the thermal effluent discharging into Cape Cod Bay and anglers fishing off the discharge jetties and from boats in the plume l which is visible in the background by the calm water. Striped bass and bluefish, which are attracted to and concentrate in the thermal current, are the dominant species sought by sport fishermen at this , location. l l l a, 1 m- - . ,.., 4 . ;. _ =n
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III. RESULTS AND DISCUSSION A. IMPACT OF PILGRIM STATION ON FISHERIES RESOURCES
, 1. COMMERCIAL LOBSTER POT-CATCH FISHERY Pooled lobster (Homarus americanus) catch statistics from the surveillance (discharge) quadrats (H-11. H-12, I-11, and I-12) were compared with data from l the following reference quadrats (E-13 E-14, and F-13) located in Warren Cove (Figure 1) to assess impact of Pilgrim Station on the local lobster population and fishery. .
4 Females outnumbered males in the catch for the entire study area in 1986. i ' In the surveillance area, females Of all the lobster sampled, 58% were females. 4 comprised 54% of the sampled catch; while at the reference quadrats, males-cud females were caught in about equal numbers. The percentage of culls (any lobster with missing or regenerating claws) . 7 sampled during 1986 in the commercial fishery of the Pilgrim area was 21.6%. 4 The percentage of culls in the surveillance area was markedly lower (17.9%) , than in the reference area (26.7%). Lobster cull rate is enhanced by lobster-fishing and bottom trawl activity (Keser et al. 1973; Estrella and McKiernan-1986) ~. In Warren Cove (our reference area) commercial trawling is seasonally i j (November-March) conducted for groundfish; this may account for the higher. cull rate there. The 1986 mean catch rates (catch in number of lobster per trap haul) for - i
-legal-sized lobster ( > 81 mm carapace length - CL) in the surveillance -
(0.40 legals / trap-haul) and reference (0.41) areas were comparable. However, t , j the average legal catch rate for the entire study area was far higher at 0.77. Mean legal catch rates in the discharge area have varied little over the last l i four years, ranging from 0.47 in 1983 to 0.40 in 1985 and 1986. This con-trasts with the trend for the Pilgrim area and for coastal waters overall. 9 7 t 1
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f Figure 1. Lobster pot sampling grid for lobstermen monitored along the Plymouth ' shoreline. (Surveillance (H-11. H-12. I-11, and I-12) and reference (E-13. E-14, and F-13) quadrats are shaded.] 8
I i i
- i l With the cooler ambient temperature regime in 1984 (Estrella 1985;LLawton et al.
. 1986),' the early season molt apparently was depressed or at least delayed; this, t
.in turn, would have affected recruitment to legal size and impeded lobster activity (Campbell 1983; Estrella 1985). The mean catch rate of legal-sized lobster in the Pilgrim area 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) . According to Ectrella (1985) and Estrella and McKiernan (1986), the coastwide commercial i cctch 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 l documented for Massachusetts in 1985 (Estrella and McKiernan 1986), while pre-i j liminary indications are that 1986 is comparable to 1985. We tested catch data using several nonparametric stat'istical tests, which . I are not dependent on a given distribution but usually work for a wide range l of distributions (Sokal and Rohlf 1969). Annual legal catch rates were com-I pared for the discharge and reference areas for block periods of time. The f
- l. Kruskal-Wallis test revealed no statistical differences (P > 0.05) between areas over the entire survey and for the preoperational/outagefand operational I ysars. With the Wilcoxon's signed-ranks test of legal catch rates by year i
(operational: 1973-1983, 1985) arranged as paired observations (surveillance J 4 varsus reference), we found no significant differences in CPUE (P > 0.05) batween control and test areas. , Catch sampling data and plant output were examined for a relationship
- - using correlation analy~ sis (Sokal and Rohlf 1969) of Unit I Pilgrim Station Capacity Factor (MDC Net %) versus mean legal catch rates over time for pre-scribed areas. Sublegals were not examined in this way because of the sampling i bias of commercial pots. When two variables are significantly correlated, it l 9 l
l
._ . = m . _ . . . _ . _ _ _ .. .._
t is tantamount to determining the intensity of' association (interdependence) or I that a relationship between variables exists other than could be exacted by chance alone. We found a significant negative correlation (P $ 0.05) between
-legal lobster catch rate for thermal quadrats pooled (surveillance' area) and i .
mean annual Pilgrim Station MDC Net % Capacity Factor for operational history of the plant. We then-ran a correlation analysis on the mean Unit I thermal output for the period of May-December, which approximates the inshore lobster fishing season, versus legal catch rates for the surveillance area and obtained 7 a correlation coefficient of -0.570 which is between 90% and 95% significant.: j Conversely, when power output and legal lobster catch rates for reference l l quadrats were tested for association, no correlations were statistically veri-fiable. When two variables are correlated, cause and effect is not necessarily I validated; however, there is-the possibility of an inverse relationship between j
- the catch rate'of legal-sized lobster in the impacted area and the operating i
level of Pilgrim Station. As to the effect of current flow on catch rate, Auster (1985) reported that the speed of a water current above a critical velocity will retard the j i foraging behavior of lobster by inhibiting mobility. It'is reasonable to I conclude this might translate into reduced trap catches in the immediate discharge area. In fact, our diving observations have revealed few lobster in the surveillance area. i 1 1
- 2. RESEARCH LOBSTER TRAP FISHING J An experimental catch sampling program was devised and initiated during the summer of 1986 to assess the impact of Pilgrim Power Plant operation on i the local lobster (Homarus americanus) population. Controlled lobster trap.
4 10 i l
- . __ _ _ m. -. .__ . .-._ _ _ _ . _ __ _ . _. _ _ __
l' fishing generated data to better measure variations in population parameters than was possible sampling commercial catches. Data on size frequenc!es, sex rztios, number of culls, incidence of berried females, and catch-per-unit-sffort were compared spatially for the sampling period, late June - early i October, a time when the power plant was in an outage with only a reduced dis- , charge current present. Catch Per Unit Effort Traditionally, catch-per-unit-effort (CPUE) in the lobster fishery has
- b:en measured by catch per trap haul (CTH). However, we found that with'our
! catch of . legal lobster ( > 81 mm carapace length), there was a direct relation-chip between catch and set-over-days. This was not the case with sublegals. W2 then weighted CTH of legal lobster by inanersion or soak time (CTHSOD) and - , uced this index as a measure of legal stock density (relative abundance). A total of 2,149 lobster (all sizes) was sampled in 1,868 trap hauls. The overall average CTH in the study area for sublegal lobster ( < 81 mm CL) k wrs 0.987 (Table 1) . The legal CTHSOD averaged 0.088 for the study area. Wa examined catch rates from the two reference areas, Rocky Point and White i i Horse (Figure 2), to determine if the data could be pooled for a larger sample I. eize to be compared with the surveillance area. There was no overlap in the ! confidence limits bounding the sample mean catch rates (legal and sublegals) for the two control sites (Table 1). Employing the approximate test of equality of means of two samples whose variance ve assumed to be unequal (Sokal cnd Rohlf 1969), we found catch rates to be significantly (P < 0.001) greater _ at White Horse. With the same statistical procedure, we compared each refer-cnce area to the surveillance area to determine if we had selected suitable station pairs that responded in similar ways to most expected environmental
.11 4 . , . , - . - - - .- ,,,e, ., , ,. . ., , ,,,--e .,
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s i Table 1. Catch per unit effort from experimental fishing for American i lobster in the Pilgrim area for 1986. CTH represents catch per trap haul; CTHSOD indicates catch per trap haul per set-over-day. Catch data are presented in numbers of lobster caught. Mean i 2 standard errors is an estimate of precision. Legal-sized Lobster Sublegal Lobster Q 81 m CL) (< 81 mm CL) Mean 2 Mean 2 Area CTMSOD 2 SennAmrd Errors CTH 2 Semndard Errors Entire Study Area 0.088 0.076 - 0.100 0.987 0.934 - 1.040 , Surveillance Area 0.081 0.065 - 0.097 0.896 0.825 - 0.967 Entire Reference Area 0.096 0.062 - 0.113 1.080 1.002 - 1.158 Rocky Point (Control) 0.064 0.046 - 0.082 0.930 0.826 - 1.033 White Horse (Control) 0.127 0.099 - 0.155 1.226 1.113 - 1.340 1 i I 4 i l 12
i j - CAPE COD BAY o r k
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0 1/2 1 N SCALE IN MILES PLYMOUTHBAY A Rocky Point NC F- D
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PILGRIM
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.' SITE ,
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~ LOBSTER TRAWL STATIONS (A-H) f4 k ',,-
- Point I i
,.]. . .. 9 '-
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, ~ 3, Paw Figure 2 Location of experimental lobster gear (5 pot trawls) for Marine Fisheries Studies.
The surveillance area includes Stations A-D; the l reference areas include Stations E and F off Rocky Point and Stations G and H off White Horse Beach. 13
changes. This was appropriate in that the surveillance ' area was essentially non-impacted thermally during our lobster study in 1986 with only a reduced current discharged from Pilgrim Station. There were no significant differences (P > O.05 for both legals and sublegals) in catch rates between Rocky Point and the surveillance area. However, CPUE of legals and sublegals differed significantly (P $ 0.01 and P $ 0.001, respectively) between White Horse and the surveillance area. Miller (1983) reported that very of ten unexplicably large differences in catch rates have been obtained when fishing traps over j seemingly homogeneous substrate. Because Pilgrim Station was in an outage l during the lobster season of 1986, we considered this year's endeavor a trial l 4 experiment to work out technical problems in the field sampling design. Sex Ratio, Berried Females, and Culls The overall sex ratio of males to females in the study area approximated _ 1:1. However, when the surveillance and reference areas were compared, the J surveillance and Rocky Point reference area had slightly higher proportions , of males; whereas. the White Horse reference area had more females.' The percentage of females captured that were bearing eggs (barried) was l .. 2.9%. Keser et al. (1983) reported the percentage of berried females captured j in EasternLong Island Sound, Connecticut for 1977-81 was about 3%. The White Horse reference area was again singularly different within the study area. ~ , Of the ovigerous females sampled, 84% were captured at-White Horse,'10% at ,i the surveillance area, and 6% at the Rocky Point control area. i The percentage of cull lobster captured in experimental trap hauls was l 20.4%. The catch rate (catch per trap haul) of culls was compared spatially. ! The reference area at Rocky Point was comparable to the surveillance' area, with 0.21 cull lobster / trap haul found for the former and 0.19/ trap haul for 14
l
\
the latter. The White Horse reference area had a greater density of culls (0.35/ trap haul) . Trap related injuries, resulting in claw loss, are often casociated with fishing pressure and concomitant handling by lobstermen. Size Composition of the Experimental Catch Carapace length measurements were obtained from an experimental sample cccch of,2,149 lobster. The size distributions of lobster caught in the Pilgrim study area (surveillance and reference locations) are presented in Figures 3-6. Sharp reductions in the number of lobster caught above the minimum legal size (81 mm carapace length - CL). reflect the influence of intensive fishing exploitation. In 1986, the average CL of the experimental cztch was 72.7 mm for the entire Pilgrim area. The mean sizes of lobster in the sub-areas ranged from 72.3 mm CL (surveillance) to 73.6 mm CL (Rocky Point raference). Examining the coefficients of variation (C.V.), we found that C.V. for lobster sampled from the Rocky Point locality was 11.7% while the coeffi-cients at White Horse (reference) and at the surveillance zone were 13.0% and 13.3%, respectively. The Kolmogorov-Smirnov procedure (Sokal and Rohlf 1969) was employed to tsst size distributions of lobster caught in the different areas. We compared the two reference areas (White Horse and Rocky Point), each reference area to the surveillance area, and the pooled reference areas to the surveillance area. For paired comparisons, we tested size frequencies for lobster of all sizes, sublegals ( < 81 mm CL), and legals ( > 81 mm CL) . The results are found in Table 2. There were no significant differences (P > 0.05) in size composition between White Horse reference and the discharge surveillance. There w:re significant differences (P $ 0.05 and P $ 0.01) for all lobster (pooled sizes) and for sublegals between the other areas paired (Table 2). However, j - 15 i I e I
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i i i i ,, i i L_ 4 , , 42 46 30 56 $5 62 56 'O 74 78 82 36 90 94 9,8 *02 LOS CARAPACE LENGTH (mm) l Figure 3 Sumer size distribution of lobster captured in experimental trap hauls in the surveillance area off Pilgrim Station,1986. Legal-sized-lobster are 2 81 mm carapace length; sublegal-sized lobster , are < 81 mm carapace length; x'is mean carapace i length. 4
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42 +5 n !s 5s s2 ss n a :s 32 ss ,o 9 rs :o2 ::6 CARAPACE LENGTH (mm) Figure 4 Summer size distribution of lobster captured by experimental trap fishing at all reference stations pooled off Pilgrim Station, 1986. Legal-sized lobster are > 81 mm carapace length; sublegal-sized lobster are < 81 mm_ carapace length. x is mean carapace length. 17
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CARAPACE LENGTH (nun) Figure-5 .Sureer size distribution of lobster captured in 6:perimental'. trap hauls at the Rocky Point reference area, north of Pilgrim Station, 1986. Legal-sized lobster are > 81 mm carapace length; i ' sublegal-siz.ed lobster are < 81 mm carapace length. x is mean carapace length.
. 18
16 13 14 - ., 13 - 12 - 1 I 11 - g i i Q 10 - l I U e- I a l g s. g 1 O" 7 - 81 m m i D 6 J I I g _ l M 3* 1 4- l
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Figure 6. Sumer size distribution of lobster captured in experimental trap hauls at the White Horse reference area, south of Pilgrim Station,1986. Legal-sized lobster are > 81 m carapace length; sublegal-sized lobster are < 81 m carapace l length; x is mean carapace length.- j l i 1
. 19
Table 2 . Kolmogorov-Smirnov_ test of sampling areas for size distributions (all lobster..sublegals, legals) of lobster captured in the Pilgrim area by experimental trap fishing, 1986. White Horse Rocky Point Entire (reference) (reference) Reference Surveillance area N.S. ** - all lobster N.S. ** sublegals (< 81 mm CL) - legals (2 81 mm CL) N.S. N.S. N.S. Rocky Point (reference) all lobster * - - sublegals ** - - legals N.S. - - N.S. Not significant
- Significant at 95% level
- Significant at 99% level
- No comparison made l 20
~^
there were no differences (P < 0.05)'in size composition of legals between ; treas compared. In conclusion, our 1986 field research lobster trap study was a-trial cxperiment under essentially prestress conditions (i.e., plant outage). This, fortuitously, was time well spent, for our work became a uniformity trial where we fished identical traps in a standardized manner over the proposed a' axperimental area. The proper pairing of potentially impacted / treatment sites t-with non-impacted / reference sites was of prime importance, for we assume that pcpulations at both locations respond in a similar way to changes in abiotic variables. The invalidity of the assumption would negate the assessment of stress at the surveillance location when the power plant resumes operation. Based on preliminary trapping, we cannot justifiably pool the reference areas - White Horse and Rocky Point - for data comparisons with the discharge area. White Horse differed markedly from Rocky Point and the surveillance area in most population parameters examined. However, except for the size composition of sublegals, Rocky Point (control) and the surveillance area appear-to be cn appropriate station pair to assess population level effects of power plant operation.
- 3. NEARSHORE BENTHIC FINFISH Station 1 (Warren Cove) was considered the primary reference site and was compared with surveillance Station 3 (Discharge). No waste heat was-discharged by Pilgrim Station in 1986 after early April, making 1986 basically.
aquivalent to 1984 as an " outage" year. However, a current was maintained - from the discharge canal year round, as at least one circulating pump was i in continuous operation. 21
i e l Mean annual catch rates for the three dominant groundfish winter flounder-(Pseudopleuronectes americanus), windowpane (Scophthalmus aquosus) and little skate .(Raj,aa erinacea) - were examined for differences between reference and surveillance sites (Figure.7). Mean annual CPUE of winter I flounder for 1986 at Station 3 exceeded that of Station 1 for the first' time since the nearshore trawling study began in 1981. In'1984, another " outage" year, Station 1 winter flounder catch indices were nearly double that of Station 3; hence, the apparent change in this species distribution noted in i 1986 was not related to output of heated effluent. Since 1984, little skate annual catch rates at Station'1 have steadily 4 increased; concurrently, annual CPUE at Station 3 has declined since 1983. Windowpane annual catch indices increased slightly at both stations in 1986. If differences in fish distribution (indexed by CPUE) resulted from plant-operation, one would expect to see differences in 1986 data at Stations 1 i and 3 relative to previous years, with the possible exception of the outage i year, 1984. This was not apparent, as 1986 abundance indices (Figure 7) for these dominant species remained consistent with the overall~ increases and decreases in annual CPUE during on-line years, indicating no measurable impact on the three groundfish species evaluated. A similar conclusion was reached from trawl data for the outage year of 1984 (Lawton et al.1985). 4 Seasonality of Trawl Data We nave used annual mean trawl CPUE of selected finfish species to i measure changes in relative abundance over time. Within the annual CPUE of
, a species may be marked seasonal patterns of abundance. The variances of a species' seasonal mean CPUE are less than that of the corresponding annual i
catch rate; hence, seasonal CPUE's are a more precise statistic to analyze
! timeseries trawl data.
22 l
Winter floundar 25 - 20 1982 1983 1984 1985 1986 Year l Windowpane 25. 20. j 15-2 y 10-l 1982 1983 1984 1985 1986 Year Little Skate Reference Station 1 25- E S"rvei aace Station 3 20_ a 15-3 I 1982 1983 1984 1985 1986 Year Figure 7 Mean annual catch per standardized tow of three dominant groundfish by bottom trawl at reference Station 1 and surveillance Station 3, 1982-1986. 1 23
. _ _ _ . - - _ _ ._. _ _ _ _ _ _ _ . - . . _ _ _ _ _ _ _ _. _ _ _ . . -- - _ - - _ _ . . _.i
0-To investigate seasonal variation in trawl catch rates for 1986 at the four stations sampled, we partitioned catch data for little skate, winter flounder..and windowpane by season: winter (January-March), spring (April-June), summer (July-September), and fall (October-December) . Choice of seasonal demarcations was based'on bottom trawl catch rates and sea water temperature data collected in the Pilgrim area over the last decade.(Lawton et al. 1983). After inspection of little skate seasonal catch rates (Figure 8), stati-stical t-tests (Sokal and Rohlf 1969) were run on mean seasonal CPUE between , l all station pairs for spring, summer and fall (Table 3). In spring, the CPUE at Station 4 was significantly greater than at Stations 3 and 6. In summer, Station 6 had a significantly greater catch rate of little skate than Station 1. In fall, CPUE of Station 4 was significantly greater than Stations 3 and 1 j and Station 6 was significantly greater than Station 1. The mean seasonal CPUE's of little skate at Stations 3 (discharge) and 1 (reference) were not
- significantly different throughout 1986.
Windowpane seasonal mean catch rates (Figure 9) were statistically analyzed by t-test for differences between stations within a season (Table 4). The spring windowpane catch rate at Station 1 was significantly greater than at the other three stations. In summer, windowpane CPUE for Stations 1 and 6 were both significantly greater than Station 4 CPUE. The fall CPUE for 2 Station 4 was significantly higher than the corresponding rates for Stations 1 and 6. Winter flounder seasonal mean CPUE's (Figure 10) were tested for signi-ficant differences between stations within a season.by an approximate t-test, (Table 5) as station CPUE variances within each season were heteroscedastic 24
Little Skate Winter ! Spring I Sumer Fall T- .. 25 -' 17.9 - Station Key 1
~
- 1. Warren Cove
- 3. Discharge - "
20 - 4. White Horse ..
- 6. Intake E 15 ~ ~'
e _. m., t .m s - u ::j;- 10 - i - ~ 5 7.r [ :: 1 i !!!I '
'l r i 34 6 1 3 4 6 1 3 46 1 34 6 Station Station Station Station Figure 8 . Seasonal mean trawl catch rates with vertical error bars for little skate by station in Pilgrim area, 1966.
25
, . _ _ - - = . - . .- .. _-
l Table 3 . . Significance of differences between station seasonal trawl catch rates of little skata.. 4 i .I SPRING Station 6 Station 4 Station 3- .j l Station 1 1.29 7.72 1.15 l Station 3 0.14 8.87* Station 4 9.01* I I SUMMER Station 6 Station 4- Station 3 l Station 1- 7.05* 0.87 3.40
~
Station 3 3.65 2.53 Station 4 6.18 4 FALL Station 6 Station 4 Station 3 4 Station 1 2.89* 5.81** 1.24 Station 3 1.66 4.57* Station 4 2.92 .
- denotes significance at p $ .05
** denotes significance at p $ .01 1 1 based on t-test l l
1 I 4 i i-26
Windowpane Winter l Spring, l Summer Tl Fall 6.s 25,.1 T J. +4.9 _ 12 . 11 _ _ e 10 ~ s.
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' Station Key _ _,"
9~ 1. Warren cove -
- 3. Discharge
- 4. White Horse
8- 6. Intake ~ $ 7- _ 3 6- - S- *
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:9 g g g g 1 3 4 6 13 46 1 34 6 13 46 Station Station Station Station Figure 9 . Seasonal mean. trawl catch rates with vertical error bars for windowpane by station in Pilgrim area, 1986.
I 27
Table 4 . ' Significance of differences between station seasonal trawl catch rates of windowpane SPRING Station 6 Station 4 Station 3 Station 1 6.61* 6.05* 7.44** Station 3 0.82 1.39 Station 4 0.57 SUMMER.
- Station 6 ' Station 4 Station 3 I'
Station 1 2.26 6.60** 3.84 Station 3 6.10 2.76 l Station 4 8.86** FALL f
. Station 6 Station 4 Station 3 f
Station 1 0.24 2.83* 0.84 Station 3 0.60 1.99 i Station 4 2.59*
- denotes significance at p $ .05
~
** denotes significance at p f .01 1
based on t-test l
. 28 i
i 1 l W 5ter Flounder Winter l i Spring . Summer I Fall 1 .9 19.1 25 - - 20 - Station Key
- 1. Warren Cove
- 3. Discharge' --
- 4. White Horse
- 6. Intake
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Bf g 1 3 46 1 34'6 1 346 1 3 4 6 Station Station Station Station Figure 1D. Seasonal mean trawl catch rates with vertical error bars for winter flounder by station in Pilgrim area, 1986. l
-29
Table 5 . Significance lof differences between station-seasonal trawl catch rates of winter flounder, SPRING Station 6 Station 4 Station 3 Station 1 19.23** 7.80** 4.41* i' Station 3 ,14.82** 3.39 Station 4 11.43** SUMMER Station 6 Stativu 4 Station 3 Station 1 20.83** 9.94** 4.83* i Station 3 16.00** 5.12
- Station 4 10.88 FALL i
4 i Station 6 Station 4 Station 3 Station 1 4.70 1.40 0.40 Station 3 5.10 1.80 Station 4 3.30 i i j
- denotes significance at p $ .05
** denotes significance at p $ .01 1 based on approximate t-test i
4 4 l
. 30 1
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(Sokal and Rohlf 1969). The winter flounder catch rate in spring at Station 6 w:s significantly greater than at every other station; whereas, the spring CPUE et Station 1 was significantly less than that of the other stations. In summer, winter flounder CPUE for Station 6 was significantly greater.than Stations 1 and 3, and Station l'was again significantly less than all other ctations. In fall and winter, there were no significant differences amongst cny of the station pairs. Previous analyses of trawl data indicated the Intake (Station 6) to be o haven for small ( f 20 cm total length) winter flounder, presumably due to the algal cover and sheltered environment (Lawton et al. 1985, 1986). To test this seasonally, we subjected this year's spring and summer data for i vinter flounder to the Kolmogorov-Smirnov test, for differences in length-frequency distribution between Station 6 and the other stations. There were no significant differences in the spring size distribution of winter flounder b2 tween Station 6 versus any of the other stations. In summer, significant differences existed (P $ 0.05) between Station 6 (N = 196 fish) and Stations 3 (N = 68) and 4 (N = 122). However, the only comparison of summer data (between Stations 6 and 1, p $ 0.09) where significance was not shown was based on greatly different sample sizes (N = 196 and 33, respectively). Plots of the summer percent relative frequencies of winter flounder lengths grouped in 2 cm intervals (Figure 11) illustrate that the significant difference in 1 1sngth frequeacy distributions in summer are due to a pulse of.small fish residing in the intake. 31
4 1
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4 Figure 14. Percent relative frequencies of winter flounder lengths 4 (grouped in 2 cm intervals) by station for trawl data j collected in Pilgrim Station area, July-September, 1986. 4 32 1
- 4. PELAGIC AND BENTHI-PELAGIC FISH A gill net is a passive sampler of fish, and therefore our survey abun-dance index, i.e., overnight gill net catch, is influenced by species cvailability and gear selectivity. The following assumptions were made:
- 1) gear efficiency did not change appreciably over time; 2) fishing effort of the net was uniform for each mesh size; 3) vulnerability of each species sampled was constant; and 4) the number of fish already entrapped did not influence the capture of additional fish.
Pollock (Pollachius virens) This benthi-pelagic species ranked first in the 1986 gill-net catch (50.7%). Annual relative abundance estimates, generated from catch-per-unit-offort (CPUE) data, reflect local population fluctuations throughout the-survey years (Figure 12 ). 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 in 1982 and has fluctuated some-what at a reduced level of abundance to the present. Comparing means of CPUE fc r the preoperational (1971-1972) and operational (1973-1983,1985) study years; and between 1983/1985 when Pilgrim Station operational output cxceeded 80% and 1984/1986, low output years, revealed that relative abundance
~
was only 13% lower overall during the operational study period and 17% lower in 1984/1986 than in 1983/1985 (Table 6 ) . There is no apparent relationship between the annual index for Pilgrim Station operational output and annual CPUE (relative abundance) data for pollock (Figure 14 When statistically tested, these variables were not cignificantly correlated (r = 0.138; P > 0.05). Changes in relative abundance 33
Pollock k ~ 140 - . l* 4 120 -
- l t
t
- I ft
-75 l d 3 j* F I a .. -
./ i. .. .
n i 100 " l l . I $\ *
?
g
- u. : i. . **, . . .
? :
- 1
+
~50 ~
~ 80 .
= ;
; t
- . : . : : . ?. J 60 " I # *
- I ^ l E : .
- I _ + 0 l' 3 - : : -25 40 :
J e ; Catch-per-unit-effort :: ~ ' j 20 Capacity Factor (MDC Net %).......... (( 2 s i r - i a e i e a a i : : : 71 72 73 74. 75 76 77 78 79 80 81 82 83 84 85 86 J Year Figure 12. Mean annual gill-net catch-per-unit-effort for pollock in the vicinity of Pilgrim Station and annual Unit I Capacity Factor (MDC Net %) 10)t-1986. Cunner 50 1 46 .'.. / ..',. lI - 80
^
- . l
- l} ni
- . . m 8
~
a l 1
- 1
- 1 60 g 2 35" !
- a
! ;\.
i.. I i.. - 8.u a.
.s
- :....**.... : y" 3 - # *
./ i : I - 40 l" n
u 20 .
- t. .
- : 1 I !
eu .
- Catch-per-unit-effort
- 1 -
u 10 : ; ; 20 a .. . s ! Seasonal Capacity Factor ;; 1
* ** I j (MDC Net %)
8 8 i e i s e i a a e i e i i i l 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Year Figure 13 Mean annual gill-net catch-per-unit-effort for cunner in the vicinity of Pilgrim Station and seasonal Unit I Capacity Factor (MDC Net %) 1971-1986. 34 - l l l l
Table 6. Mean catch per standard gillnet (5 panels of 3.8 - 8.9 cm mesh) set .(CPUE) for various time periods and the percent differences for selected species caught in the vicinity of Pilgria Station. 1971-1986. Species Atlantic Atlantic Atlantic Atlantic- All species Year Pollock Cunner herrina ilewife sackerel cod Teutoa asnheden Bluefish ' (pooled) 1971-1972 93.8 18.8 7.8 27.6 9.4 11.6 0.6 1.2 0.2 151.4 1973-1983. 1985 81.3 32.9 32.2 9.2 4.0 5.5 2.2 3.5 2.0 186.7 Preoperational - operational - 13% + 75Z + 3131 - 671 - 571 - 53I + 267% + 1921 + 900% + 23% percent difference ' ,u 1983 and 1985 s.n ( > 802 capacity) 62.4 25.9 9.1 5.8 1.2 3.8 5.4 1.4 3.2 135.2 . 1984 and 1986 (outage years) 51.9 22.0 11.6 2.9 0.2 1.6 4.8 1.4 1.4 117.5 1983/1985 - 1984/1986 - 171 - ISI + 272 - 50% - 831 - 581 - 111 01 - 562 ^- 131 percent difference o
i appear to reflect natural variability, probably related to year-class strength;- according to age / growth studies of Steele (1963), the fish'we catch are all! 1 juveniles. t Cunner (Tautogolabrus adspersus) 1 } Cunner ranked second in overall gill-net catch (15.5%). Annual abundance
- estimates peaked in the operational years of 1978 and 1980 (Figure 13). Cun- 1 I; -
ner, a ubiquitous benthic inshore species that is endemic in the' Gulf of Maine-
- .(Bigelow and Schroeder 1953), exhibited population consistency in the Pilgrim.
area from 1971-1976 (Figure 13).. with a grand mean CPUE for these 6 years of l 4 22 fish per gill-net set. From 1977-1983 annual catch rates were about double 4 j
- (grand mean CPUE of 41 cunner per set) that .obtained the first six years of i the survey, indicating a marked change in distribution and/or abundance of the local population. Subsequently, beginning in 1984, relative abundance j declined with the 3-year catch rate for 1984-1986 averaging 20 fish per set.
} Pooled CPUE for cunner captured during operational study years of 1973-
- i
} 1983, 1985 increased 75% from the average for the preoperational study years
- j. (1971-1972). Catch rates were down in 1984, an outage year; in 1985, a year of high thermal output; and again in 1986, a low output year.
The index for Pilgrim Station operational output for spring and summer. l the seasons when cunner are most abundant inshore, was plotted together with i catch data for cunner (Figure 13). The plot suggests a possible relationship i between the two variables. In a prior analysis (Lawton et al.1985), we
- statistically tested data on CPUE and plant operation power level for survey l 1
} years through 1983 and found a significant positive correlation (r = 0.636; P < 0.05). In our most recent analysis of the entire data series, which j included 1984 (outage year), 1985 (high output), and 1986 (low plant output) 1 36 i l 4 i
, _ . - . . _ . . . . . _ . . _ _ _ . . , ~ , , _ _ , - . . - - - _ . _ _ - _ . _ , . . _ _ . - . - . _ . _ _ . . . . - . _ , . _, _ _ ._
d:ca, we 'found a statistically significant positive correlation between variables I
- .'(r = 0.506; P $ 0.054)' . Regression analysis of catch rate on the seasonal (spring-summer) plant capacity factor for survey years yielded a significant F s
ratio (F, = 4.473; P $ 0.054) . It is evident from the observed value of F that- - the variance of CPUE of cunner'c'an be explained' partially by the regression l cn plant operational load. Specifically, 26% of the variation in cunner catch
- rcte 'is accounted for by variation in plant operational level. Furthermore, i
the overall low catch rates observed the last few years may also be indicative. of a natural reduction in stock size which is independent of station operational , fcctors. d Supporting evidence for a relationship between relative cunner abundance i j 'in the Pilgrim area and the power plant thermal outflow into Cape Cod Bay ' l ccmas from our observational diving program. . Substantially more cunner were eighted in the discharge zone than in surrounding areas from 1981-1983, when ! Pilgrim Station was operating and releasing a warm discharge current. In-1985, cunner were most abundant at Station 1D in the discharge area. Conversely, in 1984, an outage year, divers sighted relatively more cunner at reference stations than in the surveillance area, which suggests a localized shift in distribution. Waste heat was released from Pilgrim Station on only one day. in 1984, and no water current generated from April-August, when both circu-1 { lating water pumps were off. In 1986, no waste heat was released from Pilgrim i j Station into the discharge area during the cunner's stay inshore; however, one I circulating seawater pump was operated, releasing an offshore flowing cur' rent. ! During our diving study in 1986, the majority of cunner were found'in the- l
- l I discharge zone. In conclusion, there is accumulating evidence that cunner
{ tre attracted to the effluent of Pilgrim Station. This subjects the fish j
. 37 ..---._.--,_._._..,-r..__ , - . _ - _ - . - . . _ . _ _ _ . - - . - . . _ ~ _ _ - - . . . . . . . , , - , . , , - . _ . . _ . , _ - ~ , _ . . - - ,
to potential nearfield plant effects of heat or cold shock, gas bubble disease, and exposure to chemicals'(e.g., chlorine).
- Atlantic herring (Clupea harenaus harenaus)
Comprising-8.3% of the gill-net catch in 1986, Atlantic herring, a pelagic clupeid, ranked third in catch abundance. =Over the survey years,-
- annual relative abundance has fluctuated extensively (Figure 14). Until 1985, CPUE for sea herring was lowest in -1972 (preoperational study year); by far, the highest annual catch rate was obtained in 1976 (operational study year).
Catch-statistics for Massachusetts generally corroborated our findings; state-wide landings declined in 1973 but increased steadily.the.next few years, peaking in 1976 (National Marine Fisheries Service 1976). After the decline in the Pilgrim area in 1972, CPUE generally increased during the operational ; years, 1973-1977, but again dropped markedly in 1978. This was followed by CPUE fluctuating, but nevertheless, declining overall to an all-time low in 1985; a slight upswing was suggested in 1986.- The grand mean catch rate for the operational study years (1973-1983, 1985) was much greater than the average for the preoperational periode ! (Table 6). Catch rate was 27% higher for the average of 1984 (outage) and' 1986 (low plant output) than the average for 1983 and 1985 (' > 80% plant capacity). However, no power plant effect has been detected to date. No relationship is discernible in the plot of annual Pilgrim Station operational
~
output and annual catch data (Figure 14). Catch rate of herring and plant
' load' were not statistically correlated (r = 0.062; P >'O.05).
I Tautog (Tautoga onitis) Comprising 5.6% of the gill-net catch in 1986, the benthic tautog ranked fourth. Catch abundance fluctuated at relatively lov levels from-1971-1981, 38
,-war
,,mr---p-mvv, c w w s~ -m-- -,-s- y--~ e,.e-e ewwvr,e--+t-u-q- sma y- w y . m m--- ,v-,--'-,--+,.w- p w+
i i I Atlantic herring
^ 100- - 100 k
g .
..** *; j.
;; - 80 I a
80 . . . n- .. : : : a
?
g
! 1 8
- 60 =*"
*no 60 ; i.
. x w :
- 1 40
- i. - 40 2
=
ta . G a ; ; ; u . . . . e 20" ; ; - 20 m t .; . S 4
. . . . . . . . i i i i i i . .
71 72 73 74 75 76 77 78 79 80 81 82 83 S4 85 86 Year Catch-per-unit-effort
........ Capacity Tactor (MDC Net %)
Figure 14. Mean gill-net catch-per-unit-ef fort for Atlantic herring and yearly Unit I' Capacity Factor (MDC Net %) at Pilgrim Station. 1971-1986. - Tautog ,
^ 9*
8 -100 8- . x1 u , .=.
= 7 .
,,*. ...... . .! !. 80 4nx
- I*
&*8 8
A 6-. ~ [ *; : O 5. ;; * . 60 of
** , 1. : ; E, "
! . I*
- 1 m" g
s 4-l e !
. 40 g 3- "
3 e . .
- 1*
I I
- 2 ! !!
g : %I I 1
- 20 g 1- -
li 1 i . . 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Year Catch-per-unit-effort
........ Seasonal dapacity factor (MDC Net %)
Figure 13 Mean annual gill-net catch-per-unit'-effort for tautog in the vicinity of Pilgrim Station and seasonal Unit I Capacity Factor (MDC Net %). 39 l
I ( but from 1982-1986 an in rease was noted (Figure 15). Annual mean catch per set was especially low in 1975 (operational year of low thermal capacity) and high in 1985 (operational year of highest thermal capacity). Creel survey data from Pilgrim Shorefront corroborate this finding; sportfish catches of tautog were relatively low in 1974 and 1975 but peaked in 1985 (Lawton et al. 1986). The population level in the Pilgrim area appears to have stabilized once again but at a higher level the last five years. A comparison of mean CPUE for preoperational (1971-1972) and operational (1973-1983, 1985) study years revealed an increase in numbers during the latter period (Table 6). The mean of catch rates for 1984 (outage) and 1986 (low thermal capacity) was 11% lower than the average for 1983 and 1985 (high operational output). For the operational period, excluding the outage years, 1984 and 1986, we found a significant positive correlation (r = 0.590; P f 0.05) between CPUE and Pilgrim Station MDC (Net %) mean Capacity Factor for spring and summer (Figure 15) when tautog are most abundant inshore (Bigelow and Schroeder 1953). The relationship is somewhat questionable, however, for when we included the two outage years and ran a correlation, no significant relationship was found (r = 0.062) at the 95% probability level. Our diving observations off the power plant reveal that tautog con-centrate in the area of the discharge when compared to surrounding areas. Their distribution pattern increases the potential for near-field impact on this species. Alewife (Alosa pseudoharengus) The pelagic alewife comprised 2.4% of the annual gill-net total for 1986, ranking eighth in catch in 1985 but sixth this year. Over the survey years, seasonal catch abundance has been routinely highest in spring when 40 m
this anadromous pelagic species migrates inshore to spawn in natal rivers. The annual mean CPUE markedly declined in 1972 (preoperational study year) i cnd then has fluctuated at reduced levels during the operational study period (Figure 16). Catch rates were highest in 1971, followed by 1974 (operational). Catches in the Pilgrim area have been relatively low since 1984. The 1,ational l Marine Fisheries Service (1976) reported commercial landings in Massachusetts I
. from 1973-1976 ranged from 67,700 kg to 748,000 kg. An increasr. in recorded landings was not reflected in our abundance
- estimates. The difference between j the overall CPUE for the preoperational and operational study years represents a downward trend of 67% (Table 6). Between 1962 and 1984, catch rate dec11eed 68%, with low catches continuing into 1985 and 1986. There has been a general d:clining trend in relative abundance during the survey that began prior to f operation of Pilgrim Station; the nadir in the catch occurred in 1981, with a slight upswing noted in 1983 (Figure 161. We believe that decreased catches cre related to natural variability.
We found no statistical correlation (r = -0.105; P > 0.05) between catch l index and the mean Unit I Capacity Factor (index of power station operational output) for spring and summer, when most alewives were found in the study crea. River herring have been subjected to intensive exploitation along the Atlantic coast, and the trend for commercial catches has been downward
- for years (Resource Assessment Division, Northeast Fisheries Center 1983).
Thus, the decline indicated in our gill-net records appears to be wide-spread l cnd not limited to the Plymouth area. Atlantic cod (Gadus morhua) Mean annual gill net CPUE for cod, an important commercial groundfish, increased from 1971-1972 (preoperational study period) but has dropped overall during operational study years (Figure 17). l 41
Alevife
^
8
- u 30 - 100 MI e g a
* * . a N .
40 - ,
\g /\.'#.#. ,
~
80 , Yo 30 - ! t i
' t. ~60 ."
u 5 %. \ *" I, gu 20 - !: f i [* ,,.e** e 1 i 1 i 40 l"
* .s t t 0 5 Y *
. t.
e m 10 - 1 i "20 I
=
t 1
, , . . . . . . . i a i a 71 72 73 74 75 76 77 78 79 SO 81 82 83 84 85 86 Catch-per-unit-effort Year i Seasonal capacity factor (MDC Net! %) )
l Figure 16. Mean annual gill-net catch-per-unit-effort for alewife in the vicinity of Pilgrim Station .and seasonal Unit I Capacity Factor (MDC Net %), 1971-1986. 1 i l i l Atlantic cod I m
"100 g 14" -
. ;s e 12- e .I.
80 g ..=*..'#* *
- 1
- 1 v. j
* * * :1 ~ % ,
* / .
- Ii >
l "E 10-
- l *
- 1 60
. , . . . . . . " * . . i; 8" y
/ /
! i
- g O , f . g ,, i e : . :
- : . ~
a n .: = ; l \.. . . .
\; :l :\: 40 g n
f 4. l
- j ~
L* I *
- 20
[ 2J m .
- i. : i.
f - i..! A ? a i # a i . e i i e i i r , 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Year amm-mmsse Catch-per-unit-effort
........., Capacity Factor (MDC Net %)
Figure 17. Mean annual gill-net catch-per-unit-ef fort for Atlantic cod i and Annual Unit I Capacity Factor (MDC Net %) at Pilgrim Station. 1971-1986. 42
From 1973-1978, there was a steady decrease (80%) in CPUE, suggesting cod abundance had declined locally. There was a 53% decrease between the mean catch for the preoperational study period and the operational period (Table 6). CPUE began to rise in 1979 and subsequently fluctuated at slightly h!.gher
~
levels peaking in 1982 and then declining sequentially to its lowest level in 1986. Commercial Gulf of Maine cod landings in 1985 were the lowest recorded cince 1979 (National Marine Fisheries Service 1986). We have found no relationship between indices for station operational 1svel and cod relative abundance to date. No power plant effect is indicated, in that catch abundance of cod over the survey is not correlated to Pilgrim Station's operational output (r = -0.069; P > 0.05). Atlantic mackerel (Scomber scombrus) Annual catch of Atlantic mackerel, a pelagic gamefish, was highest by fer in 1971 and lowest in 1984 and 1986 (essentially outage years). Rela-tive abundance has fluctuated generally in a two-year cycle. Catch rates have declined long-term during survey years. We reported a statistically positive correlation (r = 0.477; P $ 0.10) between Pilgrim Station MDC (Net %) mean Capacity Factor for May-November, the period mackerel were found inshore, and CPUE for 1972-1983 (Lawton et al. 1985). However, this rela-tionship was indicated at the 10% confidence level, and statisticians would question the significance of a probability value greater than 0.05. A correlation indicates a relationship between variables and does not neces-I scrily imply cause and effect. When we tested the aforementioned variables 'for the years 1972-1986, which include the two outage years (1984 and 1986), the r value declined to 0.411, and the probability level was $ 0.13.
,43
3 - _. i 1 1 l Other Species 4 Not generally gill netted in large numbers, silver hake (ranked fifth in 4
- -1986 catch), Atlantic menhaden, and bluefish generally showed' increases in I catch abundance during the operational study years. . No statistical correla-
!- tions were run relating CPUE for these species and Station output because of
~p i the generally low numbers caught over the years. For all species combined .
the mean CPUE for the overall operational period increased somewhat from the , i . n't j preoperational average. There was some difference in catch rate between the mean for 1983 and 1985 and the mean for the outage years, 1984 and 1986 , (Table 6); 13% greater for the former. J j' In summation, there is mounting evidence of a relationship between-Pilgrim Station's thermal discharge and CPUE for cunner. 'This relationship 1 l may take the form of an attraction thereby affecting local distribution of i this species. ] >< l i S. FISHES OF THE SHORE ZONE I
! Fishes of the shore zone can potentially be impacted by Pilgrim Station i
via thermal stress, discharge flow, gas supersaturation, impingement, entrain-j ment, and heated backwashes. The shore-zone seine program has generated a species catalog and estimates of relative abundance of finfish residing in l the intertidal and shallow subtidal zones. As to sampling surveillance areas, ]. the rocky shoreline in the discharge area precludes seining; however, suitable 1 topography occurs at the head of the intake embayment (Station 3) . Sampled i reference stations include habitats ranging from open coastal beaches to l . the mouth of an estuarine embayment. The seine, as a sampling tool, provides t l information on the occurrence, distribution, abundance, and size range of l shore-zone fish populations. 44 i f
s 1 We exam'ned i relative abundance data'of numerically dominant species as a l t means of assessing power plant impact. Our surveys reveal large. natural vari- )
, -ctions in population levels which complicate the measuring of other than 1crge ecosystem level effects of power generation. Using correlation analyses.
we tested for relationships between monthly mean densities of the Atlantic , 4 cilverside (Menidia menidia) in the Intake at Pilgrim Station (1981-1986) and monthly Pilgrim Station thermal capacity (MDC Net %); and between the former I cad monthly plant pump capacity. We found no correlation between catch rate-I cud thermal r>utput (r = 0.186; P > 0.05) or between catch rate and pump capa-
! city (r = 0.450; P > 0.05).
Haul seining in the Intake embayment can identify potential sources of impinged fish. Of the 26 finfish species impinged from May-October 1986, 13
' w:resei$edintheIntakeandatotalof18atallstationspooledduringthe
! ccme time period. -Impingement collections for the aforementioned six months i ) w:re composed priearily of juvenile Atlantic herring - Clupea harenaus harenaus (73% of total), with Atlantic menhaden - Bravoortia tyrannus (7%) ranking a distant second. Seine catches in the Intake consisted predominantly of 4 i blueback nerring - Alosa aestivalis (42%), sand lance spp. - Ammodytes spg. ! (32%) and Atlantic menhaden (15%) . Highest seine catches were in August,
- while peak impingement months were August and November (no seining done),
i when juvenile Atlantic herring and rainbow smelt (Osmerus mordax)/ Atlantic-menhaden, respectively, were most impinged. Eight years ago in December 1978, I I a large impingement mortality of about 6,200 smelt occurred at Pilgrim Station. l l Factors found to influence impingement at power stations include the l species, numbers, physiological condition of fish in the immediate vicinity of the plant's intake screens, water temperature, circulating water pump l !. 45 s [ l 1 l
- . . . . . . - . - , .,. . . . . , - . -- - - - , - , , . _ . - , - - - -.. - -.._ - - . . . , - . . - . ~.
i ghnerated currents, and wind direction (Lawton and Anderson et al.1984). o
- Most of the large (more than 1,000 individuals) impingement mortalities at Pilgrim Station have occurred during colder months (Bridges and Anderson 1984).
i
.> Grimes (1975) believed that fish impingement increased during months of low !
l d i
- water temperatures. partly because of cold-induced sluggishness. Mov'ement
- J; f of fish out of the shallows of the shore zone into deeper water in the late i fall is triggered by. declining temperatures.. This negates the effectiveness 4
of shore seining as a sampling technique. .However, some fish reside in the deeper water of the intake channel during colder months and are, thereby,- subject to impingement for longer periods (e.g., Atlantic silverside, rainbow smelt). The Pilgrim Station Intake embayment with' its breakwaters'and dredged channel is a shoreline structure that is a haven for shore-sone fishes in an I otherwisa open coastal region. In terms of the total number of fish caught,. catch (number) per set, and number of species collected, the Intake was as
; , productive as the estuarine sampling site off the Long Point barrier beach.
i ,P Catches off the nearby exposed coastal beaches were magnitudes lower. - Fish ! concentrating in the Intake, especially in the vicinity of the Intake screen-wall, are increasingly subject to mechanical effects of the power plant. I
- . Comparing abundance (i.e., catch per standard seine haul) data (Table 7)
L over the last four years (two on-line years of high operational output - 1983 ' and 1985; two non-stress years - 1984 and 1986), we found few clear patterns . ! emerging. We don't discuss data from White Horse beach or Manomat Point 3 because the data set is incomplete. Catches in 1986 were generally down i from'1985, and in some cases markedly so, with the exception of winter flounder and windowpane. There was some agreement in'the variable direction of change 46 n --,-m - ~ , - - ,
%- - , w y,~>m----ee ,mw - w--- er , . w- - . , - - . ,
Table 7. Mean catch per standard haul seine set for selected species collected along the Plymouth shoreline, western Cape Cod Bay, 1983-1986. Stations Pooled Warren Cove Long Point PNPS Intake Ycar Mean Catch per Haul Seine Set Atlantic silverside
, . . . .,;.m 1983 103.7 197.7 30401 119.1 1984 51.2 220.9 'jilJK{M 101.7 1985 413.5 165.4 lll!13fgjj 201.5 1986 21.5 107.0 j!!2jp]l 46.9 Winter flounder 1983 1.0 4.9 Bf!!f6Ihk 2.4 1984 1.1 2.9 lii!ild!5 1.8 1985 1.0 7.4 ^!!$$$j 4.5 1986 0.4 4.3 .lif@%ll 4.3 Windowpane 1983 0.6 2.8 ll!$Asq0i*ty 1.4 1984 0.1 1.3 fidiMi! 0.5 1985 0.2 3.3 ' linfli 1.7 1986 1.3 3.7 kg!l2$$!ll) 2.4 Blueback herring 1983 1.0 13.1 0.0 t 5.6 1984 0.1 0.2 2 3? 1.1 1985 352.0 4.9 184.7 s' 178.2 1986 1.8 14.3 ' 95.9 '
32.9 Sand lance 1983 0.4 0.0 ji[(M 0.3 1984 0.5 0.2 !?Wi6!!!!' 10.7 1985 0.0 0.0 3493s!F 140.5 ! 1986 0.0 2.0 'N2$$![ 21.2 l Pooled species I l 1983 188.1 253.7 jij!jyh 176.8 l 1984 54.3 233.8 i92101 120.1 1985 854.5 186.9 lM8%)i! 569.0 1986 30.9 150.5 !!225{%i! 129.0 Shad:d column is data from surveillance station. 47
l of abundance estimates at'Long Point (reference) and Pilgrim's Intake (surveillance), but no connection to plant operation level was detected. l
- 6. UNDERWATER FINFISH OBSERVATIONS Conditions in the discharge area during the observational period reflected a composite of patterns noted during 1984 and 1985. As in the outage year of 1984, with little or no waste heat released into the environment, algal growth and density increased throughout the near-field discharge area in 1986, particularly in the discharge canal proper. However, the lush growth of kelp (Laminaria sgg,.) noted in 1984 was not found in 1986. Some kelp was present, but more common were filamentous brown and green algae, which were found-attached to most of the large rocks in the discharge canal and covering the
- large erratic found at Station Dg (Figure 18). During periods of high reactor 1
! power levels, such as 1983 and 1985, this boulder is primarily void of macro-scopic algae. In the discharge canal in 1986 there appeared to be a greater number of j blue mussels than in 1984 when population growth was somewhat reduced. The difference between 1984 and 1986, is that at least one circulating water pump operated throughout the latter year which may have brought a constant . food - supply to the mussels in the effluent canal. During plant' operation, mussel growth and occurrence in the discharge canal is enhanced, until summer when the thermal component (AT) of the waste-heat discharge combines with rising ambient water temperatures to become a limiting factor to the growth and survival of mussels in the canal. With the plant outage'(little waste heat and a reduced outflow current persisted) of 1986, the only limiting' factors { on mussel growth were available space, and predation by finfish and numerous starfish apparently attracted to the discharge canal by the plentiful food supply. r j 48
i S D, C 3 , _ _,_ 3 l f
.o-S C 2A _ iso - 2A b i
~'
Breakwater MLW s
\+ ,
\
1 i Figure 18. Finfish observational diving stations at PNPS discharge. 49 O
Finfish distributions were similar to 1985 patterns, with over 60% of all fish observed in the discharge zone and about half as much in the control zone. 4 The pattern noted for the outage year of 1984 was a more even distribution'of s ._ fish-between the discharge and control zones (44% and 49%, respectively) . . The total number of fish (1,545) observed in 1986, as estimated by divers, was somewhat higher than in 1985 (1,105) but was still markedly below that for 1984 (2,583 fish) and 1983 (2,081 fish). Species diversity (8 species) and composition in 1986 was similar to the previous three years (7 species in 1985 and 9 species in both 1983 and 1984). Cunner Comprising almost 80% of all sightings in 1986, cunner (Tautogolabrus , adspersus) were found at all stations, but were observed in greatest numbers in the discharge zone at Station D2 (Figure 19). The number of cunner sighted total'ed 1,229. an increase of'over 500 fish from 1985 (714). Comparing the number of cunner observed per dive, as an index of relative abundance for the years 1983 to 1986 (Table 8), we find ' greater densities of cunner in 1984 that far exceed several of:the years. We believe the increased sightings of cunner were the result of greater numbers of juveniles that inhabited the discharge area in the absence of a high velo-i city thermal effluent. Far fewer juveniles were sighted during the outage 4 of 1986. Lawton et al. (1986) hypothesized that in 1985 a local shif t' in distribution or stock reduction had occurred in the cunner population of the Pilgrim area, possibly due to recreational fishing pressure and/or poor year class strength. Cunner distribution in the Pilgrim area in 1986, as recorded by diving observations, was similar to that noted for 1985 and 1983 (Figures 19-20). f 50 ' e r - e .---. - - . , y-,4 ..-4 ,-,- c - . . . . - - - . + . . .-
180~ CUNNER 90-so. 1984 1986 70- . 6b 2 5o-i . 1" . 4 .. 2 ee 4b r-- t so. __a 4 I g
' i w-- i
__3
- o- i l
8 l : -l ,
, i i l- I
,- - -. i , .
r--
- ' i
. l i l I 1' g
I g i 8
-, I l l
," l l --}-- ,
3 g l S. 3. l . j 0 l C. $, I S. 3. l
- 0. ; l
,{
Stunted Senuded Control Stunted Oenudea : ntr:L .. zone zone zone zone zone :o9e l a
---- Station Zone I
Figure 19. -Distribution of cunner for each obseravtion station and zone off the Pilgrim Station discharge l canal, May-October, 1984-and 1986,-(8.8% i annual MDC). .- t 51
9 Table 8. Indices of relative abundance (fish /dihe) for two species observed by divers in the Pilgrim Nuclear Power Station Discharge canal, 1981-1986.- 4 Species Years 1981 1982 1983 1984 1985 198_6_ Cunner total study area 115.7 110.5 91.9 171.9 59.5 57.8 discharge area 57.5 52.5 42.1 64.2 26.2. 56.6 Tautog total study area 5.2 10.4 9.5 4.0 19.4 12.1 discharge area 3.8 8.9 8.6 2.8 19.3 11.1 i I 1 t 52
,, CUNNER 90 -
b
~
"'" 1983 1985-1
'70-l 60 -
m 3 7 50 - - U
" 40 30 ., ,
I & I l 8 6 20 - a 1 r- - -' g r-- g _q 8 __J ' i i L__ i l i l I - g 1 I ~~7 , , 10 - g a 3 I t-i : 1-F - r- - ] a l e L_. i I a 1 g g I 8 8 l 1 ! ( 5, l S. O l 3, 0, l C. I s, l S. 3. l :. :. ; c i.
$$unteJ zone 3gnuded zone
- IncroI zone 8
stunced zone
- e r.u c e!
~
.I:rel
- one 2. a e
---- Station Zone i
Figure 20. Distribution of cunner for each observation station and zone off the Pilgrim Station discharge canal, May-October, 1983 and 1985 (>80% annual MDC) . l- . 53
- ' + w ~ -* -=s
Cunner were primarily found in the discharge zone (64.5%), less often in the control zone (32.4%), and only occasionally (4.6%) in the stunted zone. During the outage year of 1984 (no heat or current), cunner were most abundant in the control zone (54.7%), with fewer observed in the discharge (37.4%) and stunted (7.9%) zones. Analysis of cunner distribution suggests an attraction to the warm-water outflow at Pilgrim Station, as cunner are most often found in the discharge zone during yeara of high power plant operational output. Lawton et al. (1985) reported a significant positive correlation between catch rate of cunner by gill net and plant output (as measured by the Pilgrim Sta-tion Capacity Factor). During 1986, though no waste heat was produced by Pilgrim Station during the diving study, at least one circulating water pump continued to operate for most of the observational period. What appeared to be an attraction of cunner to the thermal plume as a whole, may in fact be an attraction to the current component and not the heat. Olla et al. (1975) reported that " cunner feed both in the water column and benthically" and will orient themselves to face into a current. They further reported that cunner generally feed as individuals, but will concentrate in an area that has an abundance of food, Concentrated fee' ding activity will attract other cunner from nearby areas. yte Pilgrim discharge canal which fosters an abundance of both algae and f invertebrates, and when at least one of the circulating water pumps i's operating, provides a large volume of suspended material and seems to serve as an attractive feeding area. The heat component appears to be less attracting than the pump-induced current. It may even limit the size'of cunner aggre-gations or occlude their presence in the discharge area altogether during mid-to-late summer. It should be remembered, however, that data from the observational study is somewhat qualitative and limited by visibility. 54
Tautog Tautog (Tautoga onitis), 'second in observed abundance (11%), occurred. primarily at Station D2 (Figures 21-22). We observed tautog most often in close association with the large boulders that form the jetties and floor of the discharge' canal. These structures serve as protection and shelter (011a st al. 1975). Tautog feed primarily on blue mussels when available (Olla et al. 1975). As previously-noted, mussels are found in great numbers in the area of the discharge canal. In that we found no statistical correlation (P > 0.05) between occurrence of tautog (using an abundance index of tautog/ dive at the discharge stations) and seasonal (April-September) plant tharmal output, it would seem that the presence of an abundant food source (blue mussels) in an area offering protective shelter is the primary attraction of tautog to the discharge area. The number of tautog observed in the vicinity of Pilgrim Station (Table 8) has fluctuated throughout the diving survey. Some variation in CPUE of tautog appears in our experimental gill net catches. These changes in relative abundance are apparently related to natural variability. Pollock Pollock (Pollachius viranal was third in abundance (8.4%), but generally occurred in small aggregates. Observation of this species by divers has always been sporadic and occurrence at a particular observation station (Figures 23 and 24) does not appear to follow any pattern. - The relative abundance of pollock in the Pilgrim area seems to depend more on natural popu-lation variation than any effect of Pilgrim Station (Lawton et al.1986). Striped bass Striped ' bass (Morone saxatilis) were observed infrequently by divers (10 fish) in the discharge area. Their low numbers can be partly attributed 55
TAUTOG on_ 1983 1985. 90-p-, ' 80 I I i . I i 1 i 70_ y 1 e l I l_ T- - - 'l 1 I { I 60- 1 I i .
~
l .
- I l I
5 i I I E I I S $o- 1 .- I
! I i -
I l l E I I i 1 !
- c. 1 40- 1 I I I I I 1
1 ' g
-g 30- I _I I I I I I I I I 1
~8 2% i i i .I j i l i l i I
I t o- ! i
-7 i i ~~l i
; I I I
I l_ ._ _ o I . Sg lS 2 D1 D2 Cg l C2 S1 !S 2 Dg ll D2 Cg . l C 2 Stunted Denuded Control Stunted -Denuded Control zone zone zone zone zone zone
---- Station Zone Figure 21. Distribution of tautog for each_ observation station and zone'off the Pilgrim Station discharge canal, May-October, 1983 and 1985 (>80% annual MDC).
56
t g gf_ , TAUTOG i 1984 1986 90-
- 80.
- F" ' ,
l l l
. I 4 70- 1 ; . l I
8 I 60- l g (--. ,
, I I
- I 1
= 1 j 0- l
- I I 4
- I a l -
l i
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3.
! l 1
I I i 30- 3
) I I
r- - - i 1 20 I ' I I I I I 3 1 1 3 I I 8 I j ; 0-. I 1
-a- -I I I j
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-_J l r 9 i f i S gl5 2 D1j 3, Cg C; S g S; J gl 3, Og O.
Stunted) 3enudedj Control $tunted Der.uded Contral' zone tone zone zone zone zone
---- Station Zone Figure 22. . Distribution of tautog for each observation '
station and zone off.the Pilgrim Station discharge canal, May-October, 1984 and 1986 (8.8% 2 annual I MDC). 57
+
100-1 POLLOCK 90-1983 1985 80-i 1 70- -z 60-
=s0- r- - -
! I .
E I - c I
-, i
.! 40- l .g ) i I
- I I I e i e 30- g ,
I I I e s *7 a i 20 -, ; g l Y-- l i 10-l l i
- -l I I I g .
4 1 y 1 i 1 I I f* * " I e o S l5 1 2 0 lD 2 C lC 2 1 S S D lD C lC 1 1 2 1 2 1 2 Stunted Denuded Control Stunted . Denuded cuatres zone sone sone zone zone *one-
~
l ---- Station i 4 ' Zone Figure 23. Distribution of pollock for each observation station and zone off the Pilgrim Station discharge canal, May-October, 1983 and 1985 (>80% annual MDC)'. 4 58 i
. , - - . - - . . - , , - . , c- -- - . - - - - , . - , - - -
1 -_ _._ ._
.ggn, POLLOCK'. '
1984 1986' 90 - 80 , . 70 . 60 -
,150 - .
- I y I E '
40 - J I . I i 30 , I I
't 1
20 - : i l I i-io - , r-- ' l 3
' 1
__J -- 3 S t I 5: l3 1 l 3: C t I c. st _s,l s t s2 -et Ic 5'iai:* "*" d:d C'23 :1 se;og 4 s.; gage co;;gi
---- Station Zone Figure 24 Distribution of pollock for each observation I station and zone off the Pilgrim Station discharge canal, May-October, 1984 and 1986 (8.8% x annual MDC).
59 i I
. . - _ . . -. . . . - . ~ . . . . _. -. -- - . . _ . ..- ..
to the reduction of a thermal current during the study period. This' species has demonstrated a marked affinity for the Pilgrim Station discharge when the. I~ . plant is fully operational (Lawton'.et al.1986). 1
- j. ~ ~
2-
- 7. SPORTFISHING ,
Overall, angling activity and sportfish catches at Pilgrim Shorefront in f 1986 were among the lowest on record since the area opened in April 1973. We attribute this, at least in part, to labor strikes which occurred at the power j= plant during the fishing season and to the extended station outage. Fishing 4 . . - j effort was curtailed in that the Sh'orefront was closed to the-public for 68 days (28%) of the 1986 April-November fishing season (244 days). .Throughout; f almost all of the fishing season, Pilgrim Station released no waste heat'into Cape Cod Bay. Only one circulating water pump was operating during this period j which'resulted in a reduced flow of water.from the discharge canal. i It is readily apparent that power outages at Pilgrim Station have markedly
~
l [ reduced sportfish catches at the Shorefront, especially of striped bass and i i bluefish. In 1983 (high operational year) an estimated 1,000 bluefish and 150+ striped bass were caught by anglers at the Shorefront. Likewise, in 1985-(high output capacity) an estimated 2,200 bluefish and almost '400 bass were landed there. Conversely, with the absence. of a_ heated effluent during l L the fishing seasons of 1984 and 1986 (outage periods), the catches of bass I and bluefish declined drastically to under 100 fish total.for both species and years combined. We conclude that the operation of Pilgrim Station has a positive effect on sport fishing off Rocky _ Point by concentrating popular i game fish at a point source within casting distance from shore. However, this. attraction to the thermal discharge increases the potential for fish kills ! caused by gas supersaturation and thermal stress. i < 60 I i __ _ _ . _ ._ __ ._- ~ _ _ _
L' B. IMPACT PERSPECTIVE For the reader's convenience, the.following summary table is provided of i the major findings impacting fisheries'. resources in the inshore sector of I
. western Cape Cod Bay, centering on the area around Pilgrim Nuclear Power Sta-tion (Table 9). As the summary is not all inclusive and only' highlights calient points, the reader is encouraged to read the comprehensive discussion of relevant issues found in the individual sections of this report.~
Western Cape Cod Bay supports commercially important fisheries: lobster, L Irish moss (red algae), and groundfish; and an intensive seasonal recreational ~ l hook-and-line fishery. The population dynamics of an individual species are j influenced by a complex interaction of biotic interrelationships, including intra- and interspecific coactions with abiotic factors (e.g., water tempera-i ture and currents). The assessment of ecological impact of Pilgrim Station 1 operation on the area's fisheries' resources involves measuring mary of the !- parameters that influence distribution and abundance of the target species. Bised on nonradiological monitoring data collected to date off the power 4 _ station, there have been local biotic changes and environmental disruptions documented; these have been localized (site specific). $ Although no major perturbations have been detected in the' ecology of western Cape Cod Bay as a result of plant operation, the potential for future impact, either overtly by plant action or indirectly by altering community
]
structure, exists. As Pilgrim Station has operated at an average of slightly-more than-50% of its operational capacity, we may not yet have realized the-plant's full potential for impacting marine resources. Impact assessment at i this level of plant output may not be valid at long-term higher operational 1svels. i 61 i 4 7- u g' W v 'n-- 3 y p ey e - y--r v y- y V W- y r-' -Mww' - w-- a v w- y Me ---i-wr
. 8
, Table 9. A summary of impact assessment by study of Filgria Nuclear Fower Station (FNFS) on marine fisheries' resources in western Cape Cod Bay during the operational history of the power plant.
Investigation teosct of FNFS 1983/1984/1985/1986 Ci; neats Gill-met study Cunner evidently attracted to Relative abundance of cuaner The implications of the thermal effluent, la the area of the thermal attraction are twofoldt discharge down ta 1984 to sport fishernes this (outage year) and down is beneficial, but cea-further ta 1985 (high output versely this concentrates capacity). auggesting a fish to a high-risk area recent decline la local with the potential for stock sise. CPUE in 1986 was overfishing. thermal sLs11ar to that La 1985. acrose. gas bubble disease, and esposure to cheetcals. ( There is a (9) relationship between Relative abundance of Some as above. CPUE for tautog and FNFS operational tautog was not opprect, ably = ou tpu t, dif ferent over these years. SCdgA enservagione Supporting data that cuaner are lacreased cunner sightings in With me thermal effluent in attracted to the plant discharge the cootrol sene in 1984 and 1984. there was an apparent current. La the discharge la 198% shif t in distribution of 1985. and 1986 (reduced runner evey from the die-current). charge (denuded) some and toward the contrel nose. Concentrations of striped bass in for the first time stace 1979 he base exhibit a prefer-the vicinity of FNFS linked to the bluefish and base were not este for moving water, cooling water discharge. sighted by divere in the such as PNFS effluent, environs of FNFS in 1984 but their alsence from the were again eighted in 1985 diving area in 1984 is in small schools frequesting apparently related to the the discharge area. Caly a lack of discharge flow few base were seen in 1986. during the outage. Creel survey With the plant operating the Over 1.000 bluefish and > 150- Power Flaat has had a outfall at FNFS has preven to be en striped base were cought by peettive effect en the attractive feeatag ground concen- anglers et rNFS in 19833 sad sport fishing of f Rocky trating 8Portfish for an extended 2.200 bluefish and almost 400 Fetats however, the attrac-period of time in a location close bass in 19853 no base and only tion of game fish to the to shore.J a small number of bluefish discharge Lacreases the were caught la 1984. Catches potential for everfishing were once again low in 1986 a local stock and for fish during the plant outage. killa via high temperature and gas supersaturation. Bluefishing was prolonged inte November 1985 by the presence of the hot-water discharge. Haul-seine study intake embayment with its break- Seine catches in the Intake theremone finfish residing water and dredged dhannel appears increased in 1984 and 1985. in the Intake, especially in to be a haven for fishes in an but were down in 1986. the vicialty of the intake otherwtae span coastal region, screen vall. are subject to plant entrapment. impingeoest and thersal backwash effects.
, Trawl study Winter flounder may aveld the ' A bimodal distributtaa of Autumn trends (plate) of immediata aree of the dis- flounder reistive abundance relative abundance for winter charge canal. was found at the surveillance fisunder were different station in 1984 that was not at reference versus surveil-found for 1981-1981 1985. and lance sites from 1981-1983
' 1986. In 1986. CPU 1 in the (operational years) but discharge area exceeded that were aLa11er in 1984 (outage at the reference location. year). In 1985. we found CPUs to be correlated (+) at reference odd discharge areas. Concentrating in the channel of Catch-per-ef fort for winter Catch abundance of winter the intake embayment are flounder. flounder dropped markedly in flounder and fe* total
, , 1984 and 1985 at both the groundfish was higher in reference and discharge the intake embayment in statione. CTUE stabilized the spring and summer.
- in 1986. This is a boon to recrea-tional fishermen at FNFS Sherefront.
P
Table 9 Trawl study (cont.). e. The intake at FNFS. an altered A comparison of 1983 to 1984 This estuation has the
- environment, has characteristics is not applicable because (relatively obeltered habitat with potential for negative rock and algal cover) which apper- routine trawling was not com- impact for it increases ently attract juvenile fish. ducted ta the latake in 1983. ouaceptibility to However, coopering the ' impingement and back-catches la the intake with week efforts.
the other ettee sampled 1984 1986 we founs that sub-stantially larger numbers of
, ess11er fish (viadowpane, winter flounder) were in the intake channel ta susper.
Lobster pot-catch study There may be a onnection between a FNFS cooling water discharge and Catch rate of legal lobstere A sigelficant negative legal lobster catch kate in the declined evere11 in the study correlaties (F $ 0.05) thermally-affected ares, area la 1944 from the 1983 existe for annual level and was the lowest value thermal capacity and for the 15-year study 1egal lobster catch rate
-increasing again la 1985 by la the impacted area about 1005. In 1986. CPUE - and a correlaties (nega-4 was the highest of the entire tive) (F $ 0.10) between gurvey. seasonal thermal espacity and catch.
Dissolved gas analysis la Augvat 1903. FNFS wee operating and gas tubble disease at er near 1002 cepecity water No CSD incidente ebeerved la Cae supernaturaties (CBD) incidenta at 1933. La 1984. FNps had no resulted la several temperatures in the discharge were thermal component to induce PNFS. as high,se 30.5 C and dissolved noteworthy incidente of CSD. This was also the C8D in fish at FNFS. gases were supersatuteted (Nittogen case in 1986.
+ argon saturation levele ranged Morta11 ties of 43.000 from 112-1195). An estimated 600 and 5.000 edult men-silversides and 300 juvenile mee- hades occurred in the discharge in 1973 and heden were afflicted with CBD in 1975. respectively, the discharge canals flah were stressed,but mortality, which vse Striped mullet schooling likely, wee act evidenced. in the discharge were afflicted in late 1975.
CEO can severely stress or kill (outright or through increased
" oueceptibility to die-esse er predation) fish residing in the discharge.
I t i 63-I e
-w
I l
!' V. ACKNOWLEDGEMENTS j We acknowledge the contributions of the numerous staff members of the Massachusetts Division of Marine Fisheries who assisted in phases of field sampling especially Neil Churchill, Joseph O'Gorman, and summer intern Gary Nelson; and of Leigh Bridges in editing the final manuscript. We thank John Karbott and Chris Kyranos for allowing us to sample their lobster pot catches; and W. C. Sibley and Richard Schneider for overseeing the collection of creel data at the Shorefront area. Also, greatly appreciated is the work of Carleen Mackin for typing this report. Finally, we thank Robert D. Anderson and the Pilgrim Advisory-Technical Committee for over-seeing the entire study program.
I i i J l l 1 64 l ? I
i LITERATURE CITED 1 4 Auster, P. J. 1985. . Factors affecting catch of American. lobster, Homarus americanus, in baited traps. NOAA National Undersea Research; Univer-sity of Connecticut, Groton, CT. 46 pp.
'Bigelow, H. B. and W. C. Schroeder. 1953. Fishes of the Gulf of Maine. U.S..
- Fish and Wildlife Service. Fishery Bulletin 53
- 1-577.
i . . Bridges, W. L., and R. D. Anderson. 1984. A brief survey of Pilgrim Nuclear Power Plant effects upon the marine aquatic environment, p. 263-271. In,:
- J. D. Davis and D. Merrinan (editors), Observations on the ecology and biology of western Cape Cod Bay, Massachusetts. Springer-Verlag, Berlin, FRG, 289 pp. -
1 1 Campbell,' A. 1983. Growth of tagged lobsters (Homarus americanus) off Port Maitland, 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. Massachusetts Division of Marine Fisheries, Boscon, MA, USA. 58 pp. ! Estrella, B. T., and D. J. McKiernan. 1986. Massachusetts coastal commercial. , ! lobster trap sampling program, May-November,-1985. Commonwealth of Massachusetts Dept. Fisheries, Wildlife and Environmental Law Enforcement. j Division of Marine Fisheries. 74 pp.
- Grimes, C. B. -1975._ Entrapment of fishes on intake water screens at a steam j
electric generation station. Chesapeake Science 16(3): 172-177. Kaser, M., D. F. Landers, Jr., and J. D. Morris. 1983. Population character-istics of the American lobster, Homarus 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 :
j to survey finfish off Pilgrim Nuclear Power Station. In: Marine Ecology i Studies Related to Operation of Pilgrim Station. Semi-Annual Report No. 21. Baston Edison Company, Boston, MA. 9 pp. , l Lawton, R. P., R. D. Anderson, P. Brady, C. Sheehan, W. Sides, E. Kouloheras,
! M. Borgatti, and V. Kalkoski.. 1984. Fishes of western inshore Cape Cod Bay: studies in the vicinity of the Rocky Point shoreline, p. 191-230.
- Ijs
- 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. . i s )
! 65 I I
- - - , - _ - , , .-_-.,,_,,...m-~ -,,,,.m..m_ _ _ . _ . , y..y,, . ,, ,,7 , y --_--. ,_,,-.,.y-7 ,,.,.-v---* r - +-
v Lawton, R. P., C. Sheehan, V. Malkoski, S. Correia,'and M. Borgatti. 1985.' Annual report on monitoring to assess impact of Pilgrim Nuclear Power Station on marine fishery resources of western Cape Cod Bay. Project.
- Report No.'38 (Jan.-Dec. 1984). Irt
- Marine Ecology Studies Related to Operation of Pilgrim Station, Semi-Annual Report No. 25. Boston Edison Company, Braintree, MA, USA..
i 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 i Power Station on marine fisheries resources of western Cape Cod Bay. Project Report No. 40 (Jan.-Dec.1985) . Jja: _ Marine Ecology Studies Related.co Operation of Pilgrim Station. Semi-Annual Report No. 27.
- Boston Edison Company, Braintree, MA.
Milleri R. J. 1983. Considerations for conducting field experiments with ! baited traps.- Fisheries 8(5): 14-17. National Marine Fisheries Service. 1976. Current fisheries' statistics (No. f 7179), Massa chusetts Landings, Dec.1976. National Oceanic and Atmos-
~ pheric Administration.
National Marine Fisheries Service. 1986. Report of the third NEFC stock f I assessment workshop. Northeast-Fisheries Center, Woods Hole, MA. ; Reference Document No. 86-14. Olla, B. L. , A. J. Bajda, and A. D. Martin. 1975. Activity, movement, and feeding behavior of the cunner, Tautogolabrus adspersus, and comparison of food habits with young tautog, Tautoga onitis, off Long Island, New York. Fishery Bulletin 73: 895-898.
- l. Resource Assessment Division, Northeast Fisheries Center. 1983. Status of the fishery resources of the Northeastern United States for 1982. NOAA Tech-nical Memorandum. NMFS-F/NEC-22. 128 pp.
Sokal, R. R. and F. J. Rohlf. 1969. Biometry: the principles and practice j of statistics in biological research. W.-H. Freeman and Company. 776 pp. . l Steele, D. N. 1963. Pollock (Pollachius virens) in the Bay of Fundy. Journal' l of.the Fisheries Research Board of Canada 20: 1267-1314.
- j. .
i ) s ! l 66 l
. .__ ._ a
Appendix A 4 Winter Flounder CPUE '
' Station 1 Station 3 Station 4 Station 6 N xt2- N -x 2- N xi2- sy N t2-s y sy sy Winter 6 2.0 1.02 7 1.1 2 0.92 6 1.6 2 2.12 5 2.0 1 1.72 , Spring 7 3.9 1 1.84 10 8.4 2.42 10 11.7 1 2.42 7 23.2 7.86 Summer 9 3.6 1.34 8 8.4 2 2.72 9 13.6 1 3.64 8 24.4 1 9.10 8.1 4.22 Fell 9 6.7 1 2.66 8 6.3 1 3.50 8 6 11.4 2 7.44 Windowpane CPUE i '
Station 1 Station 3 Station 4 Station 6 N xt2- N xi2- sy N x!2- sy N xi2- sy sy i Winter 6 0 7 0.3 ! 0.36 6 0. 5 0 i Spring 7 12.0 1 5.08 10 4.6 1 1.98 10 6.0 t 2.22 .7 5.4 3.24 Summer 9 9.8 4.94 8 5.9 i 4.18 9 3.2 1 2.70 8 12.0 6.78 Fall 9 1.1 2 0.62 8 2.0 1.42 8 3.9 2.36 6 1.4 ! 1.18 Little skate CPUE ! Station 1 Station 3 Station 4 Station 6 N x22- sy N xt2- N x12- sy. N xt2- sy sy Wincar 6 0.3 2 0.42 7 0.8 1 1.26 6 0.6 1 0.80 5 0.2 1 0.48 l Spring 7 14.4 ! 7.04 10 13.2 6.86 10 22.1 7.94 7 13.1 5.68 ' Summer 9 11.2'! 5.62 8 14.6 111.12 9 12.0 7.98 8 18.2 1 5.88 Fall 9 1.9 1.30 8 3.1 2.60 8 7.7 1 3.10 6 4.8 2.60 l l l Sazzonal mean catch by station per standardized tow and its standard error for. ; i thras dominant groundfish caught by bottom trawl. N = number of tows. ' I l
, 67 , , - , , , -. -- - -. - -, -e , ,- - - - - - -
l FINAL SEMI-ANNUAL REPORT Number 29 (. volume 1 of 2) ' to BOSTON EDISON COMPANY on BENTHIC ALGAL AND FAUNAL MONITORING AT THE PILGRIM NUCLEAR POWER STATION January-December 1986 (Characterization of Benthic Communities) April 15, 1987 BATTELLE OCEAN SCIENCES 397 Washington Street Duxbury, Massachusetts 02332 Battelle is not engaged in research for advertising, sales prcmotion, or publicity purposes, and this report may not be reproduced in full or in part for such purposes.
TABLE OF CONTENTS SECTION PAGE EXECUTIVZ
SUMMARY
................................................. 1 INTRODUCTION..........................................,............ 7 METHODS AND METHODS............................................... 9 QUANTITATIVE ALGAL AND FAUNAL SAMPLING......................... 9 QUALITATIVE TRANSECT SURVEY.................................... 13 LABORATORY ANALYSIS............................................ 20-DATA ANALYSIS.................................................. 23 RESULTS........................................................... 27 FAUNAL STUDIES................................................. 27 ALGAL STUDIES.................................................. 55 QUALITATIVE TRANSECT SURVEY.................................... 69 CONCLUSION........................................................ 78 LITERATURE CITED.................................................. 79 i l [ l l l l 1
LIST OF TABLES TABLE PAGE 1 The 37 Indicator Species Used in the Quantitative Community Analyses.................................... 22 2 Faunal Species Richness, March 19.86................... 29 3 Faunal Species Richness, September 1986................ 30 4 Faunal Density With and Without Mytilus Edulis, March 1986............................................. 33 5 Faunal Density With and Without Mytilus Edulis, i September 1986......................................... 34 6 Rank Order of Abundance for the 15 Dominant Species, March 1986.................................... 39 7 Rank Order of Abundance for the 15 Dominant Species, September 1986................................ 40 8 Information Theory Diversity values (Shannon-Wiener) by Replicate and for Station Data, March 1986.......... 43 9 Information Theory Diversity values (Shannon-Wiener) Excluding Mytilus Edulis by Replicate and for Station Data, March 1986....................................... 43 1 10 Information Theory Diversity Values (Shannon-Wiener) by Replicate and for Station Data, September 1986...... 44 11 Information Theory Diversity values (Shannon-Wiener) Excluding Mytilus Edulis by Replicate and for Station Data, September 1986................................... 44 12 Species Groups Identified by Inverse Cluster Analysis of March 1986 Benthic Faunal Data..................... 53 13 Species Groups Identified by Inverse Cluster Analysis of September 1986 Benthic Faunal Data.................. 54 14 Dry Weight Biomass Values (g/m ) for the Chondrus crispus, Phyllophora spp., Epiphytes, the Remaining Benthic Species, and Total Algal Biomass for Manomet Point, Rocky Point, and Effluent Subtidal (10' MLW) Stations for March 1986................................ 6n 15 Dry Weight Biomass values (g/m2) for the Chondrus crispus, Phyllophora spp., Epiphytes, the Remaining Benthic Species, and Total Algal Biomass for Manomet Point, Rocky Point, and Effluent Subtidal (10' MLW) Stations for September 1986............................ 61 11
L_IST OF TABLES (continued) TABLE PAGE 16 Colonization Values for Chondrus crispus and Phyllophora spp. for the manomet Point, Effluent, and Rocky Point Subtidal (10' MLW) Stations for March 1986 and September 1986.................................... 67 17 Colonization Index values for Chondrus crispus and Phyllophora spp. for the Manomet Point, Rocky Point, and Effluent Subtidal (10' MLW) Stations for March and September 1986.................................... 68 ( iii
LIST OF FIGURES FIGURE PAGE 1 Location of the Rocky Point, Effluent, and Manomet Point Subtidal (10' MLW) Stations..................... 10 2 Rock Substratum Airlift Sampling Device................ 12 3 Diagram of Qualitative Transect Survey................ 16 4 Writing Tablet Used by Divers for the Qualitative l Transect survey....................................... 18 5 Species Richness for the Period September 1979 through September 1986......................................... 32 6 Faunal Densities (M ) for the Period September 1979 through September 1986................................. 36 7 Faunal Densities (M ) Excluding Mytilus edulis for the Period September 1979 through September 1986....... 37 8 Mytilus edulis Densities (M2) for the Period Se 1979 through September 1986....................ptember ........ 38 9 Dendrogram Showing Results of Cluster Analysis of March 1986 Data Using Bray-Curtis and Group Average Sorting. Shaded Area Highlights Effluent Replicates.... 46 10 Dendrogram Showing Results of Cluster Analysis of March 1986 Data Using NESS and Flexible Sorting. { Shaded Area Highlights Effluent Replicates............. 47 11 Dendrogram Showing Results of Cluster Analysis of September 1986 Data Using Bray-Curtis and Group Average Sorting. Shaded Area Highlights Effluent Replicates............................................. 48 12 Dendrogram Showing Results of Cluster Analysis of September 1986 Data Using NESS and Flexible Sorting. Shaded Area Highlights Effluent Replicates............. 49 13 Dendrogram Showing Results of Inverse Cluster Analysis of March 1986 Data Using Bray-Curtis and Group Average Sorting. Shaded Areas Hi Groups..................ghlight Different Species
............................... 51 14 Dendrogram Showing Results of Inverse Cluster Analysis of September 1986 Data Using Bray-Curtis and Group Average Sorting. Shaded Areas Highlight Different Species Groups......................................... 52 s
iv
I LIST OF FIGURES (continued) FIGURE PAGE 15 Algal Community Overlap (Jaccard's Coefficient of Community) and Number of Species Shared Between Replicate < Pairs at the Manomet Point, Rocky Point, and Effluent Subtidal Stations (10' MLW), March 1986....... 57 i . . 16 Algal Community Overlap (Jaccard's Coefficient of Community) and Number of Species Shared Between Replicate Pairs at the Manomet Point, Rocky Point, and Effluent Subtidal Stations (10' MLW), September 1986........................................ 58 i 17 seasonal Fluctuations in Total Chondrus Biomass at the Manomet Point, Rocky Point, and Effluent Stations i during Spring and Fall Sampling Periods for the Collections between September 1982 and September 1986......................................... 63 i 18 seasonal Fluctuations in Total Mean Algal Biomass at the Mancmet Point, Rocky Point', and Effluent Stations during Spring and Fall Sampling Periods for the Collections between September 1982 and September 1986......................................... 66 i 19 Configuration of Denuded and Stunted Zones for March 31, 1986........................................ 70 20 Configuration of Denuded and Stunted Zones for June 19, 1986...............................'.......... 72 21 Configuration of Denudad and Stunted Zones for September 24, 1986..................................... 74 22 Configuration of Denuded and Stunted Zones for December 17, 1986..................................... 76 1 V
4 l 2 EXECUTIVE
SUMMARY
This report presents the results of benthic algal and ! faunal studies conducted from January through December 1986,'under Purchase Order No. 68288, relative to operation of the Pilgrim Nuclear Power Station' (PNPS) in Plymouth, Massachusetts. These l investigations represent the most recent phase of a long-term Eonitoring effort by Boston Edison Company (BECO) to assess the inpact of PNPS on the inshore benthic community of western Cape Cod Bay. The benthic monitoring program has been refined in scope during the past several years by the Pilgrim Administrative Technical Committee, in conjunction with Boston Edison Company, and currently consists of the following components: o Semi-annual quantitative sampling (March and September) at the Effluent surveillance station, and at the Rocky Point and Manomet Point reference stations, o Quarterly mapping (March, June, September, and December) of the nearfield acute impact zones by means of diver observation. In 1986, quantitative samples were collected on March 31 and September 24, and qualitative impact zone surveys .were conducted on March 31, June 19, September 24, and December 17. Of particular interest during this reporting period was the prolonged I power outage that began at PNPS in early-April 1986 and was continuing at the time of this writing, as well as shorter outages that preceded this in March 1986. Beginning with the current report, the odd-numbered Semi-Annual Reports (Annual Reports) will be presented as two volume sets. Volume 1, titled " Characterization of Benthic Communities," will present details of methods, data, and results-for the current reporting period from the perspective of characterizing the benthic communities found in western Cape Cod Bay. Volume 2, titled " Impact on Benthic Communities," will interpret the results of this study in terms of impacts associated 1
- . , , n ,s ., ..,y. - - , -s-,.
- . -. . - .- - .-. - = - .
with PNPS. It is hoped that- presentation of results and conclusions in two volumes will more adequately fulfill the needs of a wider range of readers. A variety of analytical techniques was used to assess ' community structure. Specific data on algal biomass, dominant fauna, and densities of selected faunal species .were also j investigated. Field collections and laboratory analyses were, in j most cases, identical'with techniques used by former contractors. l 2 Every effort was made to ensure that the long-term comparability. l of the database would not be compromised because of changes in ! contractors over the -course of the program. We have carefully i noted any changes in techniques that were deemed necessary. j l I l l QUANTITATIVE STUDIES 1 l 2 j As in previous samplings, five replicate 0.1089 m j benthic samples were collected with scuba at three stations: Effluent, Manomet Point, and Rocky Point. Samples were preserved in the field and transported to the laboratory, where the faunal and algal fractions were separated and analyzed. Data were I analyzed on the Battelle VAX computer system u ' sing software previously used to analyze PNPS data. The results of the quantitative component of this study indicated that faunal species . richness, faunal: diversity, and total algal biomass in western Cape Cod Bay exhibited seasonal. cycles of low values in spring followed by high values in fall. Faunal densities do not reflect an obvious seasonal cycle. 4 Faunal-Studies 4 Systematics. Two new species were added to the taxonomic l list associated with the benthic monitoring studies at PNPS as a 2 l
4 result of analysis of the 1986 quantitative samples. The two species were both annelid polychaetes and were found at the !
; Effluent station in September. l Species- Richness. In March 1986, the Manomet Point reference station had th'e highest number of faunal species for pooled replicates, followed by the Effluent station and the Rocky Point station. Average species per replicate ranked.the Manomet Point station first, followed by the Rocky Point station and the j Effluent station. By September 1986, the Effluent station ranked J first for pooled species and the two reference stations had equal numbers of species. The Effluent station ranked last for average species per replicate in September, indicating a patchy faunal distribution at that station.
Faunal Density. Total faunal densities were highest at 4 the Rocky Point station in March 1986, followed.by the Effluent 4 station and the Manomet Point station. The Rocky Point station continued to exhibit the highest faunal densities among the three stations in September 1986; however, the Manomet Point station ! ranked second and the Effluent station ranked third. Relative ranks of the three stations remained unchanged in spring and fall when Mytilus edulis counts were excluded from the data. Species Dominance. Replicate samples from all three stations contained high percentages of arthropods in both spring and fall 1986. Examination of the dominant 15 species at each station revealed similar dominant species composition among the stations. This observation was consistent with previous findings. Species Diversity. In March 1986, the Manomet Point i station exhibited the highest species diversity for total fauna, followed by the Rocky Point station and the Effluent station. In September 1986, diversity values were again highest at the Manomet Point station, but the Effluent and Rocky Point stations had reversed relative ranks. Removing Mytilus edulis from the data l affected diversity values in March and September by increasing j diversity at stations where Mytilus was most abundant (Effluent station-March, reference stations-September) and decreasing l diversity at stations where Mytilus was least abundant (reference 3
stations-March, Effluent station-September). This effect reflected i the variable contribution of this species to the total fauna at the three stations. Measures of Similarity. Normal cluster analyses performed on the 1986 replicate data showed the samples collected l at the reference stations to be more similar to one another than to any of the Effluent station replicate samples. This has been l the case for most of the previous samplings and indicates a source of variability between the Effluent and reference stations caused , by PNPS operations Algal Biomass l Systematics. No additions to the cumulative algal species list were made as a result of analysis of the 1986 samples. Algal Community Description. The rock and cobble substrata found at the Manomet Point, Rocky Point, and Effluent stations continued to be colonized heavily by red macroalgae in 1986, especially by Chondrus ~ crispus and Phyllophora spp. Epiphytic algal sp2.les were observed at all three stations, with Chondrus and Phyllophora serving as the primary hosts. The most commonly observed epiphytes were Spermothamnion repens, Polysiphonia spp., Cystoclonium purpurem, Ceramium rubrum, Phycodrys rubens, and Callophyllis cristata. Algal Community Overlap. The Manomet Point and Rocky Point reference stations showed a higher degree of species overlap with one another than with the Effluent station in 1986. Overall species overlap between stations showed a relatively homogenous distribution of algal species among the three stations. Algal Biomass. Total algal biomass at all three stations decreased from spring to fall in 1986, the reverse of the typical, seasonal trend that has been observed at the three stations. Combined Chondrus and Phyllophora biomass values continued to 4
-- - . . . - . - ~ . < dominate total algal biomass at the three stations.
- Chondrus/Phyllophora Colonization Index. As is typical, Phyllophora- spp. was more heavily colonized with both algal and faunal epiphytes than Chondrus crispus in 1286. Colonization index values correlated well with- epiphytic biomass data. QUALITATIVE TRANSECT SURVEY i The diver-transect study was conducted carefully to 1 ensure comparability with previous work. Methods were identical to those used in previous years, involving a fixed transect line stretched offshore along the discharge canal centerline and a coveable line perpendicular to the fixed line. This transect was traversed by divers who noted the boundaries of the stunted and denuded Chondrus zones immediately adjacent to the effluent canal. The total area encompassed by the denuded zone in March 2 1986 was 765 m, a 17 percent reduction of the denuded zone as I compared with December 1985 (925 m 2 ). The stunted zone observed in 2 March 1986 equaled 560 m , a 90 percent increase in the size of the stunted zone since December 1985 (295 m2 ). The total nearfield 2 i impact area for the March 1986 transect survey equaled 1325 m , 9 parcent greater than that measured in December 1985.- The total area contained within the denuded zone in June
- 1986 was 812 m,2 a 6 percent increase in this zone as compared 2
with March 1986. An additional 364 m was contained within the 2 . stunted zone, for a total nearfield impact area of 1176 m ..This , represented a 35 percent reduction in the size of the stunted zone ~ and an 11 percent reduction in the size of the total impact area since March 1986. 2 The denuded zone in September 1986 equaled 867 m , ,7 percent increase since June. The increase was due primarily to the
. extension of the zone offshore from 75 meters in June to 80 meters 2
in September. The stunted zone contained an area of 374 m in I September 1986, 3 percent larger than-the area observed in June S
1986. The total nearfield impact area in September equaled 1241 2 m, 5 percent-larger t'han June 1986. In December 1986, the total area contained within the 2 denuded zone was 753 m, an area 13 percent smaller than that observed in September. The' stunted zone equaled 421 m2 , 13 percent larger than in September 1986. The total nearfield impact area 2 equaled 1174 m in December 1986, 5 percent smaller than in September 1986. 6
l 1 l l FINAL SEMI-ANNUAL REPORT Number 29 (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 1986 December 1986 INTRODUCTION This ceport presents the results of the most recent , series of benthic monitoring surveys performed 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 icpact on the inshore benthic community of the thermal effluent , from the 655 megawatt nuclear-powered, electric-generating station. PNPS is located on the northwest shore of Cape-Cod Bay, 8.06 km (5 miles) southeast of Plymouth Harbor, Massachusetts. The i 7 i
i quantitative' algal and faunal data presented and snalyzed in this report were derived from field collections conducted in. March and September 1986. Qualitative transect data were collected on March 31, June 19, September 24, and December 17, 1986. J The specificati~ons for times of sampling and procedures follow guidelines established by the Pilgrim Administrative Technical Committee (PATC) and adopted by BECO. The sampling program was modified in the summer of 1981 to include.(1) . , semi-annual (September and March) benthic sampling (quarterly samples were taken from September 1974 to June 1981); (2) three quantitative sampling sites (Manomet Point, Rocky Point, and ; Effluent stations); (3) five replicate samples (0.1089 m2) from - [ each of the three stations (three replicates were taken from I l September 1974 through June 1980 and six replicates from September ' 1980 through June 1981); (4) diver-conducted transect surveys to be performed quarterly (March, June, September, December) starting December 1981 to assess localized effects of PNPS cooling water discharge on nearfield benthic communities. Of particular interest during this reporting period were powec outages of some duration beginning on March 7, 1986, as well as the prolonged outage at PNPS that began in early-April 1986 and i was continuing at the time of this submission. To put the outages in perspective with the benthic monitoring program, the first
; quantitative samples and qualitative observations of 1986 were 4
j taken just prior to the initiation of the extended outage.(March 31, 1986). The second qualitative transect survey was conducted
~
I two months after initiation of the extended outage (June 19, 1986). Thermal loading to the nearshore waters ended in early-April 1936, while only one of two circulating water pumps 1 was operating since early-March. l ] At the request of Boston Edison Company, and beginning j with the current report, the odd numbered Semi-Annual' Reports ! ] (Annual Reports) will be presented in a new format. These reports will be produced in two volumes. Volume 1 will be titled
" Characterization of Benthic Communities" and will present j methods, data, and results for the current reporting period from a 1
8 1
-. _ , _ _ _ . , . _ . _ m-_- _-_ , , . - . , , . - _ _ -. . . . _ _ _ . _
~. . .- .
1 i 1 l biological. perspective. Volume 2, titled " Impact on Benthic 'j
- communities", will interpret the results of this study in terms of
-datecting impacts and will provide the reader with easy access _to the most significant observations and trends of the impact of PNPS
~
on- inshore benthic communities. It is hoped that presenting the i results and conclusions in these two volumes will more adequately
- fulfill 1the needs of a wider range of readers.
-Battelle's Project Manager-for the PNPS-algal and faunal I'
investigations was- Mr. Mark Curran. Algal taxonomy was performed ~ l-by Mr. Lee McKay. Faunal. taxonomy was conduct 9d by Ms. Nancy Alff.
~ Field logiatics and collections were supervised by Mr. John i Williams. Additional personnel participating in this' project
- included Mr. Phillip Nimeskern, Mr. Robert Williams, Mr. Eugene Ruff, Ms. Ellen Baptista, Mr. Russell Winchell, and Ms.. Ann Loftus.
I I METHODS AND MATERIALS QUANTITATIVE ALGAL AND FAUNAL SAMPLING i i i The field procedures are based on techniques initiated by Battelle in 1972 and adhere closely to the most recent i modifications made in subsequent years. j Benthic Sampling Stations 1 Quantitative benthic samples were collected on March 31 and September 24, 1986, at three stations: Manomet Point, Rocky l Point, and Effluent (Figure 1). The first'two stations served as southern and northern reference sites, while the' Effluent station represented the area of most immediate potential impact. All l 9 l
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y I
' Gurnet Point 0 1 i i i SCALE IN MILES PLYMOUTH BAY COD BAY Rocky Point a G Effluent (c ;., ,
P'N P S 'o . ,
..e.,,
- ~ .r . :.
mq-w - . A Monomet Point 5,.w
- .=
..\
,,..s A
5
- o
*)
. s
- .E.
"i .
. :4
! = D,.
-:a.
l r l Figure 1. Location of the Rocky Point, Elfluent,and Monomet Point Subtidal (10'MLW) Stations. 10
~ . .- . - - . . . ,-. --
4
\'
d stations were located at a depth of 3.051m (10 feet) mean low water (MLW).- The Effluent station is'directly on the center line
-of- the ' discharge. canal. The Rocky _ Point station is located
- approximately 0.25 ' nautical milesL(nm) northeast of the Effluent
, site. ..The Manomet- Point _. station ,is-located approximately 2 nn-
! coutheast of the Effluent station.
l Precise station locations . depend upon lino-of-sight techniques, with- highly visible structures' located on the shore. [ These reference points are' coordinated with'fathometer readings-to: provide precise station location.. The. Rocky Point station is i located by lining up the microwave relay tower with the PNPS off-gas stack. The Effluent station is identified as the center -
; line between the two discharge jetties.- The Manomet Point" station
.is located- by lining up the two southernmost telephone poles on j top of Manomet Point.
b Collection Techniques l All sampling was performed by a team of scuba divers. . Saapling equipment consisted of an airlift sampling device and a . metal pipe-frame quadrat measuring 0.33 m on a-sidef(rigure.2). ! The pipe-frame ensured'.that a uniform surface area of 0.1089 m 2-l was consistently sampled from each rock. A' standard scuba. tank 'I supplied the suction necessary for operation of- the airlift l I l device. A Battelle research vessel (R/V Limnoria or R/V Mya) was i used as a base. A small boat was required at Manomet Point to ! assist the divers because large rocks in the area-forced the i Linnoria to anchor slightly seaward of the station. l f At each station, divers descended to the botton with the ! ! senpling equipment and randomly selected large, flat-surfaced I ' rocks or boulders for sampling. LSmall rocks with'less:than twice the surface area of the quadrat were not sampled because.of their susceptibility to- movement or 'dislodgement during storms. Such l rocks may have an unstable resident community.- The quadrat was 11' 1
> j
! R
-. _ ,-,..-,-,.__m,.._- - - , _ _ . - . . _ ._._._,_1._ -._.-.-.__-.--_._-,._u- ,_..--..J
a e o
- O O .* 'o yl. ;.. ollected Sample Removable Catch Bag of Nytex Meeh l
l l Air Flow Regulator Plastic Tube , a >;> w f h .* o';
}:^O '
* 'o " o
- opg . Air Flow g i < ~
s I a l l v Standard Scuba Tank ( .
~
.' j ?.'
.\ Pipe Frame to Delineate Quadrant
. Suctiort Created by Upward Flow of Air Figure 2. Rock Substratum Air, t Sampling Device.
12 _ _ _ _ _ _ ._ . . _ . . _ _ _ _ _ _ _ . . _ . . . _ _ _ . _ _ _ _ _ _ _ _ _ _ . . . _ . _ . . . ~ . _ , _ . . _ . .
l placed on a rock while the airlift device was positioned a few inches above the quadrat by one diver. A second diver began scraping the area within the quadrat with a sharp-bladed tool (Red Davil Paint Scraper). The algae and resident fauna were carried by suction up the airlift into a bag (Nitex, 0.5-am mesh) at the opposite end. When the area within the quadrat had been scraped clean, the bag was removed and sealed. A new bag was then attached while a third diver took the filled sample bag and placed it .into a larger catch bag, rive replicate samples were taken at oach station, placed into the catch bag, and delivered to the vessel. On board the vessel, each sealed bag was placed in a wet ! box containing running seawater. While the vessel was underway to the next station, the contents of each bag were transferred to a 3.78 liter plastic jar, labeled, and preserved with 10 percent > formalin. Approximately 100 g of Borax were added as a buffering agent te prevent softening of calcified shells. QUALITATIVE TRANSECT SURVEY Scuba observations were conducted along the axis of the discharge canal on March 31, June 19, September 24, and December 17, 1986. This phase of the investigation mapped the lateral and offshore extent of denuded and stunted algal. zones directly in front of the PNPS discharge. The distinction between " denuded" and " stunted" is based on the distribution of the red alga Chondrus crispus. The denuded zone is defined as that area where Chondrus occurs only as stunted plants restricted to the sides and crevices of rocks. No Chondrus is found on the upper surfaces of rocks in this area except where the microtopography of the rock surfaces creates small protected I areas. In the stunted zone, Chondrus is found on the upper surfaces of the rocks, out is noticeably inferior ti. ormal spacimens in height, density, and frond development. The normal 13
I i zone begins where these factors are typical for the deoth and . l substratum in question. ) Qualitative Transect. Study Because of the complexity of this procedure, we have presented the methods and procedures followed during the-qualitative transect study in sequential order of events: I A. Laying Out Transect Line. l
- 1. R/V Limnaria & crew approach sampling area.
Batte11e's 5.49 m Boston Whaler is used to i transport transect equipment to shore. 1' Transect equipment inventory includes the following: o Base Line, 1.92 cm nylon I approximately 35 m long. l o Transect Line, 1 cm nylon with lead weights and distance marks every 10 m, 100 m long. o Anchor (Danforth) for seaward end of transect line. j l o Marking buoy plus line attached to j end of transect line. ' s o Diver-safety line, attaches from buoy to R/V Limnoria.
- 2. Two crew members transport equipment aboard the Whaler to effluent area. The Whaler is secured outside the effluent canal, and the base line is fastened to an eyebolt on the north jetty. The free end is carried across the effluent canal via the. top of the barrier net or the canal bridge. This end is attached to an eyebolt on the south jetty. The base line is drawn tight and tied off, crossing perpendicular to the effluent canal. This line provides a point of attachment for the transect line from the center of the effluent canal.
14
. __ _ . . . . . ~ . . ~ _ . . . _ . _ _ . _
1 i
- 3. The . Whaler'is maneuvered into the effluent canal and approaches the base line. The i transect line is atta:ne. by snaphook to
! the center point of *he 6.sse line. . The J
. . Whaler is c. maneuvered seawa'd parallel to the effluent canal vnil e 4 : crew member I feeds out the transect-line. -Sufficient j tension is maintained to keep the transect line straight and on center-to the effluent canal. The transect line is fed out until the- end anchor and attached buoy line are 3
reached. The buoy line11s cleated off and engine power is. used to stretch the transect line tight and align it along the
- centerline of the effluent canal. When the transect line is straight and centered, it i is lowered to the botton with the buoy j line, and the marking buoy is released.
- 4. The R/V Limnoria is positioned near 'he 1 seaward. end of the transect line and anchored. A diver safety line is rigged from the marking buoy to the R/V Limnoria
{_ to facilitate diver access.to the transect line. 'The safety line is kept sufficiently. I slack to avoid lifting the transect line. l B. The Transect survey (rigure 3). i 1. Divers don scuba gear. Three divers are required for the survey, and each has specific responsibilities: , o Diver No. 1--Serves as the dive
- leader; carries writing tablets,
- measures algal transition zones,
- makes general observations, and
- signals for transfer of the
- teasuring line.
o Diver No. 2--Reels out measuring l line perpendicular to the transect then remains stationed just line, beyond stunted zone with reel in j hand. On signal, transfers
- measuring line to successive 10-m
- marks with Diver No. 3.
l-i- o Diver No. 3--Remains stationed at
- 10-m marks of the~ transect'line.
! Attaches measuring line by snap hook i to the transect line. On signal, I transfers measuring line to 4 15 A
- - C -.
t i 'N I d go 7 - Ef fluent Line e
'of 0 g g <y . . MHW' 4
20< Weight Marks at i Om Intervals
- 30<
4 400 500 iver i Diver 3 [ Diver P_ 700 Measuring Line t (30m, marked at 5m intervals) 800
% ransect T Line 900 1000 h Anchor Diver Saf ety Line E [r E Anch or& Lin e i
V -d i l Figure 3. Diagram of Qualitative Transect Survey.
- e i
16
successive 10-m marks with Diver No. I
- 2. I l
, 2. Equipment specific to the transect study: o Two , white plastic writing tablets and pencils. Separate tablets are used for the NW and SE areas of the , transect zone. The tablets provide space.for recording measurements and observations for each 10-m interval I (rigure 4). The compass course ! (310* for the NW zone and 130* for the SE zone) for each measurement angle is written on the tablet.. o Measuring line & reel--dacron line of 30-m length, wound on plastic , reel. Line distances are marked with orange fluorescent . paint and duct i lj tape for each 5-m interval. t' o Catch bag. j o Magnetic diving compass (2) used by
- Divers No. 1 and 2.
1 ! 3. Divers No. 1,2, and 3 descend the buoy line to the seaward end of the transect line. Divers swim along transect line toward i effluent canal and note changes in Chondrus density and condition. Several passes are made by Diver No. 1- to- identify the transition zones from normal growth, to stunted growth, to denuded. These' zones are defined as follows: i o Normal Zone--Chondrus density, height, and frond development lush
, and/or apparently characteristic'of 1 1
the local natural environment. o Stunted Zone--Chondrus is found on the upper surfaces of the rocks but is noticeably inferior in height,
, density, and frond development.
o Denuded Zone--Chondrus occurs only as stunted plants restricted to the sides and crevices of rocks. No Chondrus is found on the upper >
- surfaces of rocks in this area
' except where the microtopography of the rock surfaces creates small 17
l
^
Stunted Denuded Stunted Denuded To... T o... To... T o ... 10 lIO 20 120 30 e 40 , Ii/" 2 50 ' 1 60 '-' 70
- 80 90 l North 100 v Courbe 3iO
- 8" :
Figure 4. Writing Tablet Used by Divers for the Qualitative Transect Survey. i i 18
protected areas.
- 4. Diver No. 1 records the distance from the base line where .the denuded and stunted zones intersect the transect line.
Measurement is made by interpolation between the 10-m marks to the nearest meter.
- 5. Diver No. 3 takes position at the first mark shoreward of a transition zone and attaches the measuring line to the transect line. Diver No. 2 swims from that point on
. a course of 310* and unwinds the measuring line. This establishes a line of measuremeat perpendicular to the= transect line. Diver No. 2 stops Just beyond the stunted / normal transition zone'.
- 6. Diver No. 1 checks the compass bearing of
- the measuring line and corrects the position if required. The diver then swims along the measuring line from the transect line point of attachment to the distal end.
- several passes are made back and forth in
. order to clearly define transition zones. Once the transition zone has been defined, the distance (to the nearest meter) is measured and recorded on the tablet. i
- 7. Diver No. 1 swims beyond the measurement-
. zone of normal growth, to ensure that l normal growth is characteristic beyond the i measurement area. Diver No. 1 also communicates to Diver No. 2 his perception of the stunted / normal transition zone to gain a second opinion. If there is a discrepancy, additional observations. are made to clearly delineate the transition
] zone. \ i 8. Diver No. I swims back along the measuring line toward the transect line and records 4 general observations regarding the floral / faunal assemblage.
- 9. Diver No. 1 signals for transfer of the-measuring line by tugging on the line. The line is then transferred by Divers No. 2
. and 3 to the next 10-m mark shoreward.
l This procedure is continued until each 10-m ! distance from the base line is measured and surveyed. i 19
e.
- 10. Upon reaching the north jetty, Diver No. l-
", records the distance of the. submerged jetty. ends .from the base line by comparison with . the transect line. These data serve to i calibrate the transect line position for 4 mean highwater.
- 11. Diver No. 1 swims toward the. bash line
! inside the effluent canal and recordt' algal growth characteristics in this area.
- 12. Divers No. 2 and 3 take position to measure l
transition zones on the SE side of the transect line. Measurements and-observations .are taken by Diver No. 1. Procedures follow those previously described along successive 10-m marks seaward.- Diver No. -2 swims a magnetic course of 130' to position the measuring i a line at each interval.
- 13. When all measurements and observations have been completed, the divers ascend and j return to the R/V Limnoria.
- 14. The Whaler is used to retrieve the transect 3 line and the base line; lines are stowed on the R/V Limnoria.
l 15. Upon return to the laboratory, the field notes are incorporated into a field report
- and submitted to the Project Manager.
LABORATORY ANALYSIS Faunal Processing i j i Algal and faunal components were separated in the 4 laboratory by washing the animals from t.6.e algae onto a 0.5-mm ! mesh screen. The fauna was then preserved in 70 percent ethanol. The algae were returned to 5 percent formalin. Each faunal sample was divided into one-quarter aliquots prior to sorting. One aliquot from each replicate was processed, j and the others were archived. A solution of Rose Bengal stain was 1 1 20
, - _ . . - - , _ , . , , . , , , ,s. , . , . . , _ . . . , - . . . . _ , - _ . . . , , , , , . - . , , . - , - . _ _ , . , _ _ _ _ . _ _ , . , ,
_.m.- - _ .
l j- cdded to each faunal aliquot. -Animals were sorted into major groups or to the lowest possible taxon, depending upon the individual sorter, nnd then-identified by experienced personnel
- uoing research quality stereomicroscopes and compound microscopes.
1 Species counts - did not include bryozoans, colonial hydroids, or spirorbid worms because they are attached epifauna.on l the algae and their presence in the faunal . fraction is an underestimate of their abundance. These epifauna were noted
- during the algal processing (see belowb.
l Species exhibiting very high densities,-such as juvenile J Mytilus edulis, were subsampled. i Algal Processing i 4 i The algal component of each replicate sample was
; examined, using both stereomicroscopes and compound microscopes, 1
j to determine the presence or absence of 37 indicator. species (Table 1). The indicator spscies currently under observation were chosen in September 1978 from a list of the several hundred algal species recorded from the Pilgrim study sites in the 1974-1978
- period. Selected species include members of each major algal i family and representatives of a variety of habitats. The group I
includes all of the dominant species within the-study area, _the majority of the macrophytic species, and the most common epiphytic. a
! species. Although the indicator species constitute only a small i t i fraction of the total number of species inhabiting the study area, j I
q they comprise by far the most substantial part of the algal j community as measured by both percent cover and biomass.
; Reproductive stages of various algal species encountered, algal f species present in addition to the 37 indicator species, and similarities and differences between each replicate sample were l
j also recorded. Two voucher collections were established, one ) preserved in 5 percent formalin and another as a set of permanent slide mounts. The slides include reproductive structures and 21'
TABLE 1. THE 37 ALGAL INDICATOR SPECIES USED IN THE QUANTITATIVE COMMUNITY ANALYSES. t CHLOROPHYTA (green algae) , Bryopsis plumosa Enteromorpha flexuosa l Chaetomorpha linum Rhizocionium riparium L melagonium Ulva lactuca PHAEOPHYTA (brown algae) e , Chordaria flagelliformis - Laminaria digitata Desmarestia aculeata L. saccharina h virdis Iphacelaria ci rosa RHODOPHYTA (red algae) j Ahnfettia plicata Phyllophora truncata l Antithamnion americanum P. pseudoceranoides Bonnemaisonia hamifera E traillii
! Calophyllis cristata Plumaria elegans Ceramium rubrum Polvides rotundus j Chondrus crispus Polysiphonia elongata i Corallina officinalis P. fibrillosa Cystoclonium purpureum E harveyi Gracilaria tikvahiae E nigrescens Gymnogongrus crenulatus E urceo^Iata i Membranoptera alata , Rhodomela confervoides
{ Palmaria palmata Spermothamnion repens Phycodrys rubens l 1 i i i 22 _ _ _ - - , _ _ . _ . - . _ - ~.... __. _ _ , - . _ . , _.__~._. , _ . . - . _ , - . . _ . . . _ . - ,. .._
other characteristics useful for identification. The Chondrus crispus and Phyllophora spp. fractions of occh replicate sample were examined to assess the degree of algal and faunal colonization of the host species. The algal colonizers included epiphytic. species-such as Spermothamnion repens, ceramium rubrum, Cystoclonium purpurum, and Polysiphonia spp.; the faunal colonizers were primarily the encrusting hydrozoans, bryozoans, Spirorbid worms, and mussel spat (Mytilus edulis). Each Chondrus
, End Phyllophora replicate fraction was compared with a set of foug reference samples that were ranked in order of increasing levels of algal and faunal colonization. Each fraction was assigned the
- nuretical value cf the reference sample with which it most closely cecpared. Separate algal and faunal colonization indices were then determined for the Chondrus and Phyllophora populations of each station by summing the values assigned to the five replicate sccples.
Dry weight biomass of each sample was determined for
- four separate algal fractions
- Chondrus crispus, Phyllophora j spp., epiphytic algal species, and the remaining benthic species.
Total algal biomass was also determined. Each fraction was ! waighed on a Mettler balance after drying for 72 hours in a - i standard drying oven set at 80 C. DATA ANALYSIS 5 Data analysis was performed on Battelle's VAX computer system. All data were coded onto specially designed project data i shoets as the samples were processed. Data were entered into the cosputer via a VT-220 terminal. Following data entry, a hard copy l i of the raw data was generated and verified against the original coding sheets. All data entry errors were corrected at this point. Auditing software was then employed to further examine the date for errors. i l Analytical software consisted of a suite of programs i 23 l
.,_ ~_ ... ._ __ __ ._ -_. __ - -_ . . _ _ _ _ _ _ _ _ _ . . _ _ _ _-
- ~ - , - . ~ . - - - - . .. _- - - . . .
9
' developed specifically for the analysis- of benthic-data. In
! addition to a variety of data management and modification 4 programs, these. programs' include primarily PRAREI, SPSTCL, and-f CMPnMM. PRAREI~ summarizes the data for each sample, calculates a , variety of diversity-relatud indices, and generates a rarefaction ) curve. SPSTCL is a multivariate classification package that ] allows a wide variety of user-specified options for similarity
. indices and clustering strategies. CMPHNW is similar to SPSTCL, but additionally allows. both normal and inverse ana4yses to be I performed.
) It should be noted that, because of the-new two volume i format for the semi-annual reports,. the results of analytical techniques described below for interpretation of community l parameters in terms of PNPS impact may be presented. separately ? from the actual parameter measurements. In these cases, we have attempted to prov'ide enough introductory discussion in volume 2 to J provide a smooth transition between community analyses and i i determination of impact. Analytical Techniques Rank Order of Abundance. The individual species composing the fauna at each station are rank ordered by abundance ; for each replicate. The most dominant species are listed first, followed in order by less dominant forms. The contribution of l each species to the overall total percent of the fauna is denoted by a decreasing cumulative percentage, starting with the-most l j dominant species and ending with the most rare. Basic statistical analyses including calculation of means and extrapolation to an , abundance per m 2 are performed on each replicate sample to.obtain ] ! the rank order for each station. i rollowing this organization of the data, it is possible j to determine if species composition .is- changing with time or j locality. Since some species may be more sensitive to stress than 24 i i
others, knowledge of the biological characteristics of individual dominant species is essential. Diversity Measures (Community Parameters). Several neasures of diversity are calculated for each sample and station, including the Shannon-Wiener information index (H') and evenness (J'). A jacknifed procedure for determining species richness is used, along with pooled species, in order to evaluate the contribution of rare species to the communities. This jacknifed procedure follows procedures developed by Heltshe and Forrester (1983). This procedure accounts for the fact that finite random samples of a population are not a true representation of a population. The jacknifed estimate of species richness is a function of the number of " unique" species present at each station; " unique" being defined as those species present in one and only one replicate at a station. The formula is therefore 4 (n-1) k S=S+ n where S = pooled species numbers at each station n = number of replicates k = number of unique species, defined as above. A variance (var $) and 95 percent confidence intervals can also be constructed. Similarity Measures. The most direct measure of faunal similarity between field samples is the number of species in common. The concept of species shared is biologically meaningful and can be readily visualized in terms of species distribution. Similarity measures are commonly called cluster analyses. We have used the measure of similarity developed ~by Grassle and Smith , (1976), the Normalized Expected Species Shared (NESS). This l measure is based on the expected number of species shared between random samples of size m, drawn from a population. The NESS is sensitive to the less common species in the populations to be compared.
- 25
The classic Bray-Curtis similarity measure, the most widely used clustering technique, was also used (Boesch, 1977). These values can be calculated for stations (normal) and by
< species (inverse). For.the latter, the value can be calculated using either numbers of, individuals or biomass as variables. We have analyzed the data using numbers of individuals.
Nodal Analysis. Nodal analyses were performed using the results of similarity procedures described above. Nodal. analysis is a method of relating normal and inverse classifications to aid in the interpretation of cluster analyses. The method proceeds through the use of two-way tables that show replicate groups on a vertical side and. species groups on a horizontal side. We have used this technique co measure constancy, which is defined as a i proportion of the number of occurrences of a spec es group in a - replicate group compared with the total possible occurrences. a
- The constancy index is expressed as
- i. t 13 = a g3/ (nig n)
C Where at3 = actual number of occurrences of members of species group i in replicate group j. n1 = entities in species group i. n 3 = entities in replicate group j. 4 Time-series Analysis. New results were compared with important components of the historical database to observe long-term effects of thermal discharge on the benthic community. The simplest way to compare long-term data of this sort is to compare changes in species composition over time. Changes in rank of dominants may indicate perturbation of the community, or may be merely the result of natural population cycles. For example, in the August 1981 samples, Mytilus edulis and Caprella penantis were i the most dominant faunal species at all three stations. In the l i same samples, however, two other highly placed dominants at Rocky 26
- . . -. - _ . . . . ~
k 't Point 'and' Manomet Point, Hiatella arctica and~ Margarites urbilicus, were greatly reduced in numbers _at the Effluent site. I The -past database is ' valuable to determine whether- this i relationship and others have always existed or are'related to l operation of PNPS. i I
- RESULTS Results of data collected from January through December 1986 are presented. Results from the Effluent station have been highlighted i~n several figures to distinguish this station from the two reference stations.
.i FAUNAL STUDIES i Systematics I
J 1 Two new species were added to the taxonomic list associated with' the benthic faunal studies at PNPS during 1986. Both species were found exclusively at the Effluent station. The ! two new-species, both annelid polychaetes, are listed below, i
; Autolytus prolifer: A member of the polychaete family Syllidae, this species is-found in shallow waters from the Gulf of St. Lawrence to Georgia. It is typically found among stones, algal clumps, and i- holdfasts of Laminaria spp.
Polydora commensalis: A spionid polychaete, this species is known only from shells containing hermit crabs. P. commensalis is not considered a member of the resident community since this species can be i relatively mobile through transport by a host ] animal. For this reason, P. commensalis was not ( I 27 e
. . , . - , . . - . , _ . . , - , . - _ - - - - , , . . . . . - . - - -,- ,- . - . . ,n.,.-.,,--- - . . . - - - - - . - . , , , = . - . . . . , _ . ,. , . ~ - -,,.,a-.-
included in analysis of community parameters. I The taxonomic list now consists of 465 invertebrate species that have been observed at the three monitoring stations during the course of this program. l Species Richness Species richness values for samples collected at all three stations in March and September 1986 are presented in Tables 2 and 3. Data are presented as total species.per replicate for each station, with a mean value over all replicates at each station and a cumulative total representing pooled species numbers at each station. Because the area included within each replicate 2 was 0.1089 m, the cumulative species total at each station represents a total area of 0.5445 m 2, In March 1986 (Table 2), the Manomet Point reference station had 86 species for pooled replicates, the highest number among the three stations. The Manomet Point station was followed by the Effluent station with 79 species and the Rocky Point reference station with 72 species. Average species per replicate (S) again ranked the Manomet Point station first (51.6), followed by the Rocky Point station (49.8), and the Effluent station (44.8). A jacknifed estimate of species richness (S) was also calculated for the three stations (Table 2), using procedures developed by Heltshe and Forrester (1983). The jacknifed values for March 1986 ranked the Manomet Point station first, followed by the Effluent station, and the Rocky Point station. In September 1986 (Table 3), the Effluent station ranked first among the three stations in numbers of species for pooled replicates with 85 species. The two reference stations each possessed 82 species for pooled replicates. Average species per replicate (S) ranked the Rocky Point station first (57.2 species), followed by the Manomet Point station (54 species), and the Effluent station (51.4 species). The change in relative rank of 28 l
TAELE 2. FAUNAL SPECIES RICHNESS, MARCH 1986, Station / Number of Jacknifed Estimats 4 Replicate No. Species (S) Species Richness (S) Var (S) (195% CI) Effluent 1 45 2 35 3 52 - 4 45 5 47 5 44.8 Total Species 79 100.6 1 12.46 20.16 Manomet Point 1 58 2 57 3 43 4 51 5 49 5 51.6 Total Species 36 108.4 1 19.42 48.96 Rocky Point 1 55 2 46 3 53 4 44 5 51 5 49.8 Total Species 72 37.2 1 16.24 34.24 5 = Average species per rep!!cate. CI = Confidence interval. 29 ;
TA!LE 3. FAUNAL SPECIES RICHNESS, SEPTEMBER 1986, I Station / Number of Jacknifed Estimate a Replicate No. Species (5) Species Richness (5) Var (S) (195% CI) Effluent .. 1 50 2 45 ~ 3 52 4 62 l 5 48 5 51.4 Total Species 85 107.4 1 21.54 60.16 Manomet Point 1 55 2 50 i 3 54 4 59 5 52 5 54.0 Total Species 32 9817.36 3.00 Rocky Point 1 59 2 58 3 56 4 55 5 58 5 57.2 Total Species 32 97.2 1 3.33 10.24 5 = Average species per rep!!cate. CI = Confidence interval. i 30 l
the Effluent station when considering species richness for pooled replicates and average number of species per replicate indicates a patchy distribution of the faunal community relative to the reference stations. Jacknifed species richness values ranked the Effluent station first, fol-lowed by the Manomet Point station, and the Rocky Point station. Figure 5 presents pooled species richness values plotted , for the last 19 samplings (1979-1986). All three stations generally have exhibited higher species richness values since 1984 (September) than were observed prior to that period. Also, prior to 1985, all three stations exhibited a consistent pattern of low values in spring followed by high values in fall. The change in this pattern at the Effluent station in 1985 is related to PNPS operations and will be discussed in volume 2 of this report. Faunal Density Benthic macrofaunal densities per replicate and per square meter were calculated for data collected in March and September 1986 (Tables 4 and 5). Because of the tendency in the past for extremely high densities of juvenile mussels (Mytilus cdulis) to obscure differences in faunal densities among the stations, data are presented both with and without Mytilus counts. In addition, log 10(x) transformations of the data are presented. Tests of significant differences between stations reported in Volume 2 were conducted using the log-transformed data to reduce the variation between the large and small values often seen in this study. Log-transformation also makes it quite probable that the variance will be independent of the mean (Sokol and Rohlf, 1969). Total faunal densities were highest at the Rocky Point station in March 1986 (Table 4), with replicate values ranging from 15,068 to 27,236 individuals (x=19,639). The Effluent station i ranked second, with replicate values ranging from 12,968 to 26,996 l 31
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Figure 5. Species Richness for the Period September 1979 through September 1986.
TABLE 4. FAUNAL DENSITY WITH AND WITHOUT MYTILUS EDULIS. MARCH 1986. 1 I I Density w/o Station / Density Log to(x) Mytilus Log to(x) Density Replicate No. (individuals) Density (individuals) w/o Mytilus Effluent 1 19768 4.294 12600 4.100 2 13768 4.139 9528 3.979 3 16524 4.218 10428 4.018 4 26996 4.431 18324 4.263 5 12968 4.I13 % 24 3.983 i 18005 4.255 12101 4.083 m2 165286 111087 Manomet Point , 1 16312 4.213 15208 4.132 4 2 9524 3.979 3504 3.930 3 7956 3.901 7444 3.372 4 7596 3.381 7264 3.361 5 12212 4.087 11132 4.047 x 10720 4.030 9910 3.996 m2 93410 90974 Rocky Point I I 27236 4.435 24644 4.392 2 16040 4.205 13016 4.114 3 23523 4.372 21432 4.331 4 15068 4.178 13196 4.120 5 16324 4.213 14020 4.147 x 19639 4.293 17262 4.237 m2 180236 158465 l ! x = Average density per replicate. i l 33
l I TABLE 5. FAUNAL DEN $ TTY TITH AND WITHOUT MYTILUS EDULIS SEPTEMBER 1986. i Station / Log go(x) Density w/o Log 10(x) Density Replicate No. Density ' Density Mytilus w/o Mytilus , Effluent 1 3700 3.568 3356 3.526 2 2116 3.326 1928 3.285 3 2852 3.455 2656 3.424 4 3328 3.522 3148 3.498 5 2532 3.403 2420 3.384 i 2906 3.463 2702 3.432 m2 26677 24804 j Manomet Point
! 4584 3.661 3843 3.585 2 4616 3.664 3633 3.567 ; 3 4584 3.661 3596 3.556 4 5200 3.716 3992 3.601 5 5412 3.733 4740 3.676 i 4879 3.633 3973 3.599
- m2 44739 36472
.I Rocky Point
! 3832 3.946 7343 3.395 2 7030 3.350 5843 3.767
- 3 8768 3.943 6752 3.329 4 6812 3.333 3723 3.758 5 6976 3.344 5943 3.774 i 7694 3.336 6425 3.303 i
m2 70631 58932 i s Average density per replicate. i i
- i i
l l 34 y, .,_ .. ...-, , _ _ . _ _ _ , , _..__.y -.. .m ._
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J l i individuals (x-18,005). The Manomet Point station exhibited the lowest faunal densities among the three stations, with replicate values ranging from 7,596 to 16,312 individuals (x=10,720). Faunal donsities per square meter, ranged from 180,286 individuals at the l Rocky Point station to 98,410 individuals at the Manomet Point station. The relative ranks of the stations remained unchanged j when the March 1986 data were reexamined with Mytilus counts l l romoved. i In September 1986 (Table 5), total faunal densities were l again highest at the Rocky Point station, ranging from 6,812 to !
- 8,832 individuals (i=7,694). The Manomet Point station ranked l
socond, with replicate values ranging from 4,584 to 5,412 individuals (x=4,879). The Effluent station ranked last with
- replicates ranging from 2,116 to 3,700 individuals (2-2,906). As in March, the relative ranks of the three stations remained i unchanged when Mytilus counts were removed from the data.
Total faunal densities, faunal densities excluding l Mytilus, and Mytilus densities per square meter are plotted for l 1 t the last 19 samplings in rigures 6, 7, and 8. As can be seen in i ) rigure 6, , total faunal densities at all three stations in } September 1986 were among the lowest recorded during the period ' l since 1979. Mytilus edulis counts also decreased dramatically, f compared with the reference stations, from March to September 1986 j (rigure 8). This significant decrease at the Effluent station will i bo discussed in volume 2. l Species Dominance l \ I l l i The 15 numerically dominant species present in replicate l senples collected at each station during the March and September l 1986 samplings are presented in Tables 6 and 7. Data are presented as numbers per replicate (x) and percent composition at each station. As during all previous samplings, teplicate samples from all three stations during 1986 contained high percentages of l 35
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B0_ 9/FS 82/F9 4/80 G/80 80/80 B/88 4/88 6/88 8/88 3/82 9/82 4/83 80/83 3/84 9/84 3/85 9/85 3/86 9/86 Figure 7 Faunal Densities (M2) Excluding Mytilus edulis for the Period September 1979 through September 1986.
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TABLE 6. RANK ORDER OF ABUNDANCE F0il THE IS DOMINANT TAXA MARCH 1986.
~
Number Station / Taxa G/rgplicate) Percent Effluent . Mytilus edulis 3904.0 32.79 Coroonium insidiosum 3422.4 19.01 Jassa fascata 3129.6 17.38 Iscnyrocerus antuipes 1304.C 3.33 Capreta penantis 923.6 3.14 Pontoteneia inermis $47.2 3.04 Acarina 486.4 2.70 Corophium acutum 361.6 2.01 Mitrelia luna ta 261.6 1.43 Castionius taevisculus 233.2 1.31 Proboloioes honmesi 172.8 0.96 Coroonium sp. 136.8 0.87 Isenyroceridae juv. 133.6 0.14 Harmothoe app. Juv. 121.6 0.63 Deiamine thea III.2 0.62 Total of 13 5pedIes 17673.6 M Remaining Fauna 64 spp. 331.4 2.93 Total Fauna - 79 spp. 13003.0 100.0 Manomet Polnt 3aisa falcata 3030.4 23.27 Isenyrocerus anguines 2224.0 20.73 uytitus eouiis 309.6 7.33 Mapre a penatis 740.3 6.91 Acarina 630.3 6.33 Desamine then 300.3 4.67 coropnium"TdIItum 390.4 3.64
)toooioices beimes 363.2 3.39 4ntoreneia inermis 336.0 3.13 aarAmrites nelicinus 1 96 . 3 1.34 caropnium bonetti 196.0 1.33 cintuia aculeus 123.2 1.13 Iscnyrocericae juv. 116.0 1.03 Pteusymtes glader 107.2 L.00 Capra thoas spp. Juv. 101.2 0.96 Totalof 13 species Mia.a U Remaining Fauna 71 spp. 301.4 7.s3 Total Fauna 36 spp. l0720.0 100.0 Rocky Point
!schyrocerus antures 6034.6 30.33 Jais4 laicita 4260.0 21.39 Mytilus eauus 2377.6 12.l!
Ponto(*neia inermit 1323.0 7.13 Acanna 1303.6 7.67 Proboloides hofmesi 312.0 4.13 Caropnium acutum 373.6 2.92 i Capr=tia penantis 441.6 2.39 cainopius iaemeutus 211.2 1.33 Carornium bonelli 263.0 1.36 pe < a min,""the a 213.6 1.09 Har mo ths.Tpp. juv. 207.2 l.06 ficnyroceridas juv. 104.3 0.33 Lacuna vinets 94.4 0.43 Ma trella lunat s 4),4 6 Total of 43 5 pes.es !!313.4 I.- Remaining Fauna 37 spp. 323.6 4.20 Total Fauna 72 spp. 19639.2 100.0 39
1 i TABLE 7. RAM ORDER Of' ASUNDANCE FOR THE DOMINANT IS SPECIES. l SEPTEMBER 1906. t Station / Species . S/ replicate) Percent Effluent i ggggg, 376.0 19.82 mr 357.6 12.31 vm wn app.jw. 162.4 111.2 3.39 3.83 f 70.4 2.42 1 68.8 2.37 . wrecerun 63.2 2.18 ,
; 33.2 1.90 i 32.0 1.79
.r Eas n '4:: i:n Tot 2 .8 %
Remaining Fauna - 70 spp. 340.8 18.62%
; Total Fauna - 83 spp. 2903.6 100.0 %
i
- Menomet Point i mM t lu edutis 906.4 18.38 1 Acarina 391.2 12.12 Corochlum spp.jw. 330.4 7.18 j Mamine thes 293.6 4.02 l 'leusymies giggt 260.0 3.33 <
i:oroonium insiciosum 239.2 4.90 l i j ' vincts 204.0 4.18 tai ionius laevisculus 182.4 3.74 t n g aculeus 180.0 3.69 oenen tis 134.0 3.20 oroonium acutum 133.6 3.13 ,
\terraritet be ncinut 132.0 2.71 !
i hchyrocerus a_".I:2211 !!3*8 2'64 + Caroonium boneui 103.4 2.14 i rena knearts 103.2 . l Tota o pecies )?86.e . % j Remaining Fauna - 47 spp. 392.8 13.28a6 i Total Fauna .- $2 spp. 4379.2 100.1 % 1 Rocky Point stytilut edutit 1263.3 16.49 ] Acarina 1263.4 14.45 Mataleenan tit 192.0 10.29 Ncoles sottericois 304.0 6.33 Calhooius laevitcuius 183.6 3.01 l Fleusymres 3 379.2 4.93 senyrocerus g 274.4 3.37 Ninietopp. 211.4 2.34 Wo ui 4eutent 209.6 2.72 ' Hietails aretics 208.0 2.70 Coreenium acutum. 200.0 2.60 l
\terlsritas bencinut 133.0 2.64 Mntn-mei inarmit 142.4 2.11 4
- y. snowMrat waar e nnearis 146.4 144.s 1.90 fotal of IT5pecies 6)es.3 . ' *6 Rema6ning Pauna 47 spp. I164.3 17.30 *6 fatal F auna .12 sps. 7493.4 111.1 %
n__,.i-~..,m.'n,--. ~-,:-.,;~4+.......,._ ..,,,n.....,. ., .n_g.._,.,n,,,, ,....,,e..s .,...-s, .,,,.w.c , ,.- e. g 40 i
, crthropods. This is typical of the rocky habitats sampled in rolation to this study (Davis and McGrath, 1984). In March 1986, 10 species were shared among the 15 dominant species present at occh station; nine of these were arthropods and the tenth was ) Mytilus edulis. In Sep te'abe r 1986, only 6 of the 15 dominant species at each station were shared among the three stations. Of these six, four were arthropods. A detailed discussion of species composition at all three stations in March 1986 was given in Semi-Annual Report No. 28 (BEco, 1986b). Those results can be summarized as follows. Of the 15 dominent species in replicate samples from the Manomet Point station in March 1986, 10 were also found among the 15 dcminant species in samples collected at the Effluent station, rour of the five dominant species at both stations were the same. The Rocky Point station shared 13 of the same 15 dominant species , with the Effluent station. This included three of the five most l dominant species. Mytilus edulis composed approximately 33 percent of the fauna at the Effluent station, 8 percent at the Manomet Point station, and 12 percent at the Rocky Point station. In September 1986, the Effluent station shared 9 of the dominant 15 species found at the Manomet Point station and 7 of the dominant 15 species found at the Rocky Point station. In cddition, three of the five, and four of the five most dominant species at the Effluent station were also among the five most dcminant species found at the Manomet Point and Rocky Point stations, respectively. Mytilus was replaced as the most dominant species at the Effluent station by the caprellid arthropod, i Cnprella penantis (20 percent of total). This species ranked tenth ct the Manomet Point station (3 percent of total) and third at the Rocky Point station (10 percent of total). The 15 dominant species collected at each station in September 1986 composed approximately 81 percent of the total fauna at the Effluent station, 82 percent , at the Manomet Point station, and 83 percent at the Rocky Point i station. 41 0
i species Diversity i
- shannon-Weiner diversity (H') and evenness (J') values !
j were calculated for replicate and station data collected in March and September 1986. These values are presented in Tables 8, 9 { i i (March 1986, with and without Mytilus counts), 10, .and 11 (September 1986, with and without Mytilus counts). N' and J' were i calculated for data with and without Mytilus edulis because the Shannon-Weiner index is disproportionately influenced by the presence of single overwhelmingly dominant species. Mytilus has ( ) often occurred in such high numbers at all three stations in the ; past that this species has masked diversity patterns (BECO, 1986a). The practice of calculating diversity with and without ' Mytilus counts has been continued ) for consistency with past j reports.
; In March 1986 (Table 8), the Manomet Point station f exhibited the highest species diversity (H') for total fauna, with j an index value of 3.61, followed by the Rocky Point station with a !
! value of 3.23, and the Effluent station with a value of 3.07. [ j Evenness values (J') exhibited the same relative pattern among the } three stations. Excluding Mytilus from the data (Table 9) l decreased diversity at both reference stations but increased 4 diversity at the Effluent station. This was explained by the j significantly higher contribution of Mytilus to the total fauna at I the Effluent station (33 percent) as compared with the Rocky Point ] station (12 percent) and the Manomet Point station (8 percent). ; j Diversity values for September 1986 were again highest I at the Manomet Point station (Table 10), with a station value of ! 4.49 and replicate values ranging from 4.22 to 4.51. The Manomet i Point station was followed by the Effluent station (4.42, range = ' i
- 3.93 to 4.49) and the Rocky Point station (4.36, range = 4.08 to
! 4.60). Diversity values calculated without Mytilus edulis (Table i 11) showed a decrease at the Effluent station (4.36, range = 3.84 , I
- to 4.43) but an increase at the reference stations (Manomet Point !
= 4.66, range - 4.20 to 4.61; Rocky Point = 4.45, range = 3.90 to !
. l 42 I
TABLE 3. INFORMATION THEORY DIVERSITY VALUES (SHANNON-WlENER) BY ; REPLICATE AND FOR STATION DATA, MARCH 1986. ; Replicate . Manomet Point . Rocky Point Effluent , H' J' H' J' H' J' i 3.27 0.56 2.60 0.45 2.90 0.53 2 3.71 0.64 3.31 0.60 2.98 0.58 3 3.42 0.63 2.97 0.52 2.97 0.52 4 3.30 0.67 2.93 0.54 2.85 0.52 5 3.50 0.62 3.30 0.53 3.29 0.59 Station 3.61 0.56 3.23 0.52 3.07 0.49 TABLE 9. INFORMATION THEORY DIVERSITY VALUES (5HANNON-WIENER) EXCLUDING MYTILUS EDUL15 BY REPLICATE AND STATION DATA, MARCH 1986. t t Replicate Manomet Point Rocky Point Effluent H' J' H' J' H' J' l l 1 3.12 0.53 2.37 O.41 3.07 0.56 2 3.61 0.62 3.22 0.59 3.02 0.59 3 3.23 0.61 2.73 0.49 3.20 0.56 4 3.70 0.66 2.73 0.51 2.86 0.52 l 5 3.36 0.60 3.16 0.56 3.32 0.60 l Station 3.49 0.54 3.07 0.50 3.21 0.51 i i H's Shannon Wiener diversity. J' e Evenness. i i 43
TABLE 10. INFORMATION THEORY DIVERSITY VALUES (SHANNON-WIENER) BY REPLICATE AND FOR STATION DATA, SEPTEMBER 1986. Replicate Manomet Point Rocky Point Effluent H' J' , H' J' H' J'
! 4.51 0.73 4.60 0.73 3.93 0.70 2 4.22 0.75 4.09 0.70 4.19 0.76 3 4.33 0.75 4.03 0.70 4.17 0.73 4 4.32 0.73 4.16 0.72 4.49 0.75 5 4.27 0.75 4.26 0.73 3.99 0.71 Station 4.49 0.71 4.36 0.69 4.42 0.69 TABLE 11. INFORMATION THEORY DIVERSITY YALUES (5HANNON-WlENER)
EXCLUDING MYTILUS EDULIS BY REPLICATE AND STATION DATA, SEPTEMBER 1986.
. . . . ._. . . ~ .
Replicate Manomet Point Rocky Point Effluent H' J' H' J' H' J' 1 4.61 0.30 4.61 0.79 3.84 0.68 2 4.37 0.79 4.15 0.71 4.12 0.75 3 4.56 0.30 4.29 0.74 4.09 0.72 4 4.60 0.79 4.20 0.73 4.43 0.75 3 4.26 0.75 4.29 0.74 3.90 0.70 Station 4.66 0.74 4.45 0.70 4.M 0.68 H's Shannon-Wiener diversity S' Evenness 44
i 4.43). This change in diversity with Mytilus removed was again due to the variable contribution of Mytilus to the total fauna at the three stations. ! l j i Measures of Similarity ; i av meglicate ; Normal cluster analyses using two different procedures wore performed on log transformed data (log 10x +1) c 11ected during l March and September 1986. The first procedure is one of the raost . j widely used indices in benthic ecology: the Bray-Curtis similarity { i coefficient combined with group average sorting. This procedure t
! tonds to stress the importance of common or dominant species and ,
j cil but eliminates rarer species from the analysis. The second ; consure of similarity, the Normalized Expected Species shared l j (NESS) combined with flexible sorting, tends to emphasize the l centribution of the less common species. Because there is no universally accepted method for performing cluster analyses, use j of Bray-curtis and NESS provides greater insight into the data j than either method alone. The Bray-curtis and NESS procedures performed on the l j 1986 data resulted in the similarity groupings presented in
! rigures 9, 10 (March 1986), 11, and 12 (September 1986), rn 1986, < , and in previous collections, the two procedures produced similar results. 'All of the reference station replicates (Group 1) showed a high degree of similarity to one another as compared to the Effluent station replicates (Group 2). Both procedures also tended
, to group the reference station replicates together by station; i this was especially true in September 1986 (rigures 11 and 12). I
- Roosons for the lack of similarity between the Effluent and roference stations are presented in Volume 2. l i
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i I l - l l Replicate RP1 MP1 MP5 MP4 MP2 MP3 RP2 RP3 RPS RP4 EF1 EF2 EF3 EF5 EF4 I Group ! 1 l l 2 - l l l Figure 9. Dendrogram Showing Results of Cluster Analysis of March 1986 Data Using l Bray-Curtis and Group Average Sorting. Shaded Area Highlights Effluent Replicates.
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l , I Replicate RP1 RP2 RP3 RP4 RPS MP1 MP3 MP4 MP2 MP5 EF1 EF4 EFS EF3 EF2 Group : 1 : : 2 : Figure 11. Dendrogram Showing Results of Cluster Analysis of September 1986 Dato Using i Bray-Curtis and Group Average Sorting. Shaded Area Highlights Elfluent Replicates.
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lsi: , e I ' l ,', Replicate RP1 RP3 RP4 RPS RP2 MP1 MP3 MP4 MP2 MP5 EF1 EFS EF4 EF3 EF2 Group : 1 : : 2 : f 4 Figure 12. Dendrogram Showing Results of Cluster Analysis of September 1986 Dato Using NESS and Flexible Sorting. Shaded Area Highlights Effluent Replicates.
By Species Benthic faunal data collected during 1986 were analyzed by inverse clustering procedures to identify species that exhibited similarities to one another based on their occurrence at each of the three stations. The purpose of performing the inverse analysis was to provide input for the nodal analyses discussed in Volume 2. The Bray-Curtis procedure was used to produce the clustering groups shown in Figures 13 (March 1986) and 14 (September 1986). Species that occurred at fewer than six replicates per sampling were dropped from the analyses. Six major species groups resulted from the cluster analyses performed on the March 1986 data (rigure 13, Table 12). The first group (Group A) consisted of 23 species and was the largest of the species groups. Most of the species that composed Group A in March 1986 have shown a tendency to group together in j previous cluster analyses (BECO, 1985, 1986a), indicating that 1 they are characteristic of all three stations throughout the year. In March 1986, Group A was made up of species present in between 12 and 15 of the total 15 replicate samples collected, which accounts for the similarity noted between these species by the Bray-Curtis procedure. In September 1986, the Bray-Curtis l procedure produced seven species , groups (rigure 14, Table 13), with one large group (Group A) consisting of 38 species that occurred in between 9 and 15 of the total 15 replicate samples collected. Additional smaller species groups were identified by the inverse analyses performed on 1986 data. The significance of these groups will be discussed in volume 2. 3 f i a i 50 1
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I l TABLE 12. SPECIES GROUPS IDENTIFIED BY INVERSE CLUSTER ANALYSIS OF MARCH 1986 BENTHIC FAUNAL DATA. Group A , Group C Idotea phosphorea Hiatella arctica Caprella linearis Eulalia viridis Pleusymtes glaber Ischyroceridae juv. i Lacuna vincta Group D Mitrella lunata Harmothoe spp. juv. Amphithoe rubricata Calliopius laevisculus Caprella nr. septentionalis
- Corophium spp. Nereis spp.
Corophium acutum Proboloides holmesi Dexamine thea Group E Pontogencia inermis Acarina Amphipoda juv. Caprella penantis Omalogyra atomus
! Ischyroceridae anguipes Jassa falcata Mytilus edulis Group F Idotea balthica PE91Todoce maculata Corophium insidiosum Leptonacea sp. A Crepidula plana Nemertea Nereis zonata Nereis pelagica Group B Corophium bonelli Cingula aculeus Margarites helicinus Metopella carinata Onchidoris aspera Amphipholis squamata Nicolea sp.
Nicotea zostericola Photoe minuta Alvania areolata Eualus pusiolus Strongylocentrotus droebachiensis Caprellidae spp. juv. Ophiopholus aculeata l 53
TABLE 13. SPECIES GROUPS IDENTIFIED BY INVERSE CLUSTER ANALYSIS OF SEPTEMBER 1986 BENTHIC FAUNAL DATA. Group A , Group B Idotea phosphorea Corophium spp. juv. Corophium acutum Crepidula plana lschyrocerus anguipes Capitella capitata Pontogencia inermis Caprella linearis Group C Jassa falcata Corophium bonelli Nerels spp. juv. Corophium insidiosum Strongylocentrotus droebachiensis Group D Asteroides spp. juv. Mitrella lunata Idotea balthica i Eulalia spp. Caprellidae spp. juv. Hiatella arctica Phyllodoce maculata Nicotea zostericola Proboloides holmesi Group E Eualus pusiolus Calliopius laevisculus Polycirrus eximius Lacuna vincta Dexamine thea Group F Corophium spp. juv. Caprella penantis Dodecaceria sp. A Acarina Mytilus edulis Group G Cancer irroratus I Haliclystis salpinx Photoe minuta Ophiopholis aculeata Leptonacea sp. A j Nemertea Nassarius trivittatus Pleusymtes glaber Cingula aculeus Margarites helicinus Nicotea spp. Amphipholis squamata Harmothoe imbricta Onchidoris aspera Crepidula fornicata Cerastoderma pinnulatum Nereis pelagica Nereis spp. 54
L f ALGAL STUDIES t Systematics No additions to the cumulative algal species list presented in Semi-Annual Report No. 16 (BECO, 1980) have been made as a result of analysis of the 1986 samples. Species identifications and taxonomic determinations were based on the works of Bold and Wynne (1978), Dawson (1966), South (1976), and Taylor (1957). 1 ! Algal Community Description , The rock and cobble substrata found at the Manomet Point, Rocky Point, and Effluent stations were heavily colonized by red macroalgae during the 1986 collections. The relatively high numbers of benthic species other than Chondrus crispus and l Phyllophora spp. at the Effluent station in 1986' distinguished l this station from the reference stations. :Polyides rotundus, Ahnfeltia plicata (class Rhodophyta), and:Desmerestia aculeata 1 (class Phaeophyta) were the most prominent of the other benthic species at the Effluent station. In March, Desmerestia aculeata, and Laminaria spp., Gracilaria tikvahiae were- noted only'in samples collected at the Effluent station.- Epiphytic algal species were observed at all three- ] stations in 1986 and were an important component of the algal i communities in terms of total algal biomass. Chondrus crispus and
; Phyllophora spp. were the primary host species, but other benthic species, including Ahnfeltia plicata, Polyides rotundus, and Corallina officinalis also' served as hosts for epiphytes. Red macroalgae of the class Rhodophyta were the- most abundant l
55
. _ ,- --- ~ , - - - , , , , , - , , , , , . . - . . , , - . . - - - - , , -~. - - - , , , - , ,
epiphytes in terms of species numbers and biomass contribution. The most commonly observed epiphytic species.were Spermothamnion repens, Polysiphonia spp., Cystoclonium purpuren, ceramium rubrum, and Callophyllis cristata.
- Algal Community Overlap 4
4 I l Community overlap was calculated for the March and September 1986 data using Jaccard's Coefficient of Community (Grieg-Smith, 1964) to measure the similarity in algal species , composition between the Manomet Point, Effluent, and Rocky Point stations. The coefficient provides a mathematical evaluation of the similarity between two replicates or stations using only species occurrence, without rafarring to any differences in the
, abundance of the species observed. Species occurrence. records of the 37 indicator species listed in- Table 1 were used for all i community overlap calculations.
Results of community overlap comparisons between replicate samples for each station for the March 1986 collecting period are presented in matrix form in rigure 15. Ranges of replicate overlap were 61.9 to 82.4 percent at the Manomet Point station (x=74.8), 75.0 to 95.0 percent at the Rocky Point station I (x=86.1), and 54.2 to 81.8 percent at- the Effluent station (x=66.2), indicating a higher degree of similarity 'between replicates at the Rocky Point station. The Manomet Point and Rocky
- Point stations showed the highest overlap between stations at 90.9 percent. The Manomet Point and Effluent stations had the lowest overlap between stations at 76.9 percent. The community overlap.
between stations indicated that the Effluent station differed from the Rocky Point and Manomet Point stations, but there was a high degree of homogeneity (>75 percent) in terms of species occurrences between all three stations in March. In September 1986 (rigure 16), replicate overlap values l ranged from 70.0 to 85.0 percent at the Manomet Point station i 56
-. -- - - - - ,,,-, - -n -- ,,--.,- , - , . , . . -
.n,.
n, , ,, ,,,I
I 2 3 4 5 1 2 3 4 5 1 16 13 15 16 1 15 16 16 17 2 80.0 13 15 16 Number of 2 75.0 18 18 17 Number of
' Species Species 3 65.0 65.0 14 14 Shared 3 80.0 94.7 19 18 Shared 4 78.9 78.9 82.4 15 4 76.2 90.0 95.0 18 5 76.2 76.2 70.0 75.0 5 89.5 85.0 90.0 85.7 Percent Overlap Percent Overlap A. MANOMET POINT STATION B. ROCKY POINT STATION OVERLAP BETWEEN STATIONS U Number of Community Shared Species Overlap Station Pair 1 2 3 4 5 Manomet Point-Rocky Pt. 20 90.9 1 18 16 13 13 Manomet Point-Effluent 20 76.9 2 81.8 17 13 13 Number of Rocky Point-Eifluent 21 80.8 Species 3 72.7 73.9 14 14 Shared 1
4 59.1 54.2 66.7 14 5 59.1 $4.2 66.7 77.8 Percent Overlap C. EFFLUENT ST/. TION FICJRE 15. ALGAL COMMUNITY OVERLAP (JACCARD'S COEFFICIENT OF COMMUNITY) AND NUMBER OF SPECIES SHARED l BETWEEN REPLICATE PAIRS AT Tile MANOMET POINT, ROCKY POINT AND EFFLUENT SUBTIDAL STATIONS (10' MLW), M ARCil 1986.
- - . , + _,.-u. - - . - _ , a _. . . . _ _ _ . __ , . - -s , - ,.
I 2 3 4 5 1 2 3 4 5 1 17 15 14 15 1 16 12 16 14 2 85.0 15 15 15 Number of 2 72.7 13 18 15 Number of Species Species 3 78.9 75.0 14 14 Shared 3 54.5 61.9 13 12 Shared t 4 70.0 75.0 77.8 15 4 76.2 94.7 65.0 15 O 5 75.0 71.4 73.7 83.3 5 66.7 75.0 63.2 78.9 Percent Overlap Percent Overlap A. MANOMET POINT STATION B. ROCKY POINT STATION OVERLAP BETWEEN STATIONS Number of Community v, Shared Species Overlap
<n Station Pair 1 2 3 4 5 Manomet Point-Rocky Pt. 21 84.0 1
1 21 21 17 15 Manomet Point-Eifluent 19 70.4 2 91.3 21 18 16 Number of Rocky Point-Effluent 21 77.8 Species 3 91.3 91.3 18 16 Shared 4 70.8 78.3 78.3 17 5 65.2 69.6 69.6 89.5
- Percent Overlap C. EFFLUENT STATION .
FIGURE 16. ALGAL COMMUNITY OVERLAP (JACCARD'S COEFFICIENT OF COMMUNITY) AND NUMBER OF SPECIES SHARED l BETWEEN REPLICATE PAIRS AT Tile MANOMET POINT, ROCKY POINT AND EFFLUENT SUBTIDAL STATIONS (10'
! MLW), SEPTEMBER 1986.
(x=76.5), 54.5 to 94.7 percent at the Rocky Point station (x=71.0), and 65.2 to 91.3 percent at the Effluent station (x=79.1). Replicate overlap increased from March to September at the Manomet Point and Effluent stations and decreased at the Rocky Point station. As in M a'r c h , the Manomet Point and Rocky Point reference stations showed the highest degree of overlap between stations in September 1986 at 84.0 percent. Also as in March, the Monomet Point and Effluent stations had the lowest overlap between stations at 70.4 percent. All between-station overlap values docreased from March to September 1986. Algal Biomass Chondrus crispus Biomass. Chondrus crispus biomass values calculated for the Manomet Point, Rocky Point, and Effluent stations during 1986 are presented in Tables 14 (March) and 15 (September). In March 1986, the range of replicate biomass was greatest at the Manomet Point station (366.28-799.12 g/m2), followed by the Rocky Pdint station (24.97-399.61 g/m2), and the Effluent station ( 47.19-371.51 g/m2). At the Manomet Point, Rocky Point, and Effluent stations, the mean Chondrus biomass made up 62 pa r c e n t ,', 32 percent, and 30 percent of the total algal biomass, respectlyely. In September 1986, the range of replicate biomass was gre& test at the Efffuent station (0.00-176.62 g/m 2 ), followed by 2 the .Manomet Point station (17.99-145.69 g/m2), and the Rocky Point station (329.10-239.51 g/m2). Chondrus made up 19 percent, 44 percent, and 14 percent of the total algal biomass at the Manomet Point, Rocky Point, and Effluent stations, respectively, in Septemoer. During the March 1986 sampling, the Manomet Point station had the highest mean biomass value for Chondrus (603.31 g/m2), followed by the Rocky Point station (271.11 g/m2), and the Effluent station (165.94 g/m2). The mean Chondrus biomass at the Effluent station in March 1986 was 72 percent lower than the 59
~
l l 2 TABLE 14. DRY WEIGHT BIOMASS VALUES (g/m ) FOR CilONDRUS CRISPUS, PHYLLOPilORA spp., EPIPilYTES, Tile REMAINING BENTHIC SPECIES, AND TOTAL ALGAL BIOMASS FOR MANOMET PT., ROCKY PT., AND EFFLUENT SUBTIDAL (10' MLW) STATIONS FOR MARCH 1986. 1 Chondrus Phyllophora Remaining Epiphytic Total Algal l Station Rep. crispus spp. Benthic Species Species (Total) Biomass ' MANOMET PT. , 1 748.35 (71%) 225.83 (21%) 14.87 (1%) 62.51 (6%) 1031.56 2 557.50 (66%) 206.27 (25%) 16.25 (2%) 60.13 (7%) 840.15 3 799.12 (51%) 549.70 (35%) 5.05 (0.3%) 203.98 (13%) 1557.85 4 366.28 (69%) I14.57 (22%) 5.69 (1%) 44.80 (8%) 531.43 5 545.29 (63%) 229.04 (27%) 3.12 (0.4%) 81.98 (10%) 859.34 R 603.31 (62%) 265.08 (27%) 9.00 (1%) 90.67 (9%) 968.07 { ROCKY PT. 1 318.36 (34%) 469.65 (51%) 3.03 (0.3%) 137.24 (15%) 928.28
$ 2 318.55 (37%) 380.33 (45%) 21.66 (3%) 130.99 (15%) 851.53 -
3 399.61 (41%) 459.37 (47%) 23.04 (2%) 88.68 (9%) 970.70 , 4 24.97 (4%) 401.99 (72%) 10.10 (1%) 121.92 (22%) 558.97 ' 5 294.04 (34%) 478.55 (55%) 4.41 (0.5%) %.39 (11%) 873.39 X 271.11 (32%) 437.98 (54%) 12.45 (1%) 115.05 (14%) 836.57 EFFLUENT I 47.19 (9%) 1 % .18 (35%) 118.24 (21%) 192.41 (35%) 554.02 2 131.37 (23%) 216.28 (38%) 59.30 (!l%) I53.50 (27%) 560.45 3 156.89 (37%) 106.58 (25%) 50.95 (12%) 113.38 (27%) 427.80 4 371.5i (51%) 260.53 (35%) 1.01 (0.1%) 101.80 (l4%) 734.85 5 122.74 (24%) 246.94 (47%) 35.34 (7%) 115.76 (22%) 520.78 X 165.94 (30%) 205.30 (37%) 52.97 (9%) 135.37 (24%) 559.58 i = Average biomass per replicate.
TABI E 15. 2 DRY CEIGHT BIOMASS VALUES (g/m ) FOR CHONDRUS CRISPUS, PHYLLOPHORA spp., EPIPHYTES, THE REMAINING BENTHIC SPECIES, AND TOTAL ALGAL BIOMASS FOR MANOMET PT., ROCKY PT., AND EFFLUENT SUBTIDAL (10' MLU) STATIONS FOR SEPTEMBER 1986. i Chondrus Phyllophora Remaining Station Rep. Crispus Epiphytic Total Algal spp. Benthic Species Species (Total) Biomass MANOMET PT. I 82.16 (22%) 171.85 (46%) 28.00 (8%) 90.88 2 72.89 (24%) 372.89 (18%) 236.29 (57%) 12.48 (3%) 93.27 (22%) 414.93 3 96.48 (23%) 203.89 (49%) 11.48 (3%) 103.82 4 145.69 (25%) 415.67 (29%) 268.15 (54%) 4.59 (1%) 76.84 (16%) 495.27 5 17.99 (4%) 291.47 (59%) 34.88 (7%) 151.56 (31%) 495.90 X 83.04 (19%) 234.33 (53%) 18.29 * (4%) - 103.27 (24%) 433.93 3 ROCKY PT. I 328.37 (47%) 299.73 (43%) -0 (0%) 67.94 (10%) 6 % .04 2 324.33 (48%) 284.30 (42%) 5.69 (1%) 65.83 (10%) 680.15 3 329.10 (45%) 335.90 (46%) 0.28 (<.1%) 70.23 (10%) 735.51 4 282.19 (42%) 296.79 (45%) 0.92 (0.1%) 85.74 (13%) 665.64 5 239.51 (38%) 310.65 (50%) 2.02 (0.3%) 75.19 (12%) 627.37 R 300.7,0 (44%) 305.47 (45%) 1.78 0.3% 72.99 (11%) 680.94 EFFLUENT 1 176.62 (51%) 90.42 (26%) 5.32 (2%) 72.99 (21%) 345.35 2 15.61 (3%) 93.82 (20%) 114.11 (24%) 253.46 (53%) 477.00
- 3 19.92 (4%) 232.90 (47%) 100.25 (20%) 146.15 (29%) 499.22 4 26.44 (8%) 125.40 (39%) 85.83 (27%) 83.91 (26%) 321.58 5 0 (0%) 73.72 (44%) 41.22 (25%) 51.68 (31%) 166.62 47.72 (13%) 123.25 (34%) 69.35 (19%) 121.64 (34%) 361.95 i = Average biomass per replicate.
Manomet Point station and 38 percent lower than the Rocky Point station. In September 1986, the mean Chondrus biomass value was highest at the Rocky Point station (300.70 g/m 2 ), followed by the Manomet Point station (83.04 g/m 2 ), and the Effluent station 2 (47.72 g/m ). This represented a decrease in Chondrus biomass at the Manomet Point and Effluent stations and an increase at the Rocky Point station from March to September 1986. A decrease from spring to fall is atypical for the three sampling stations, as can be seen in Figure 17. Phyllophora spp. Biomass. Phyllophora spp. biomass is given in Tables 14 and 15 for the March and September 1986 collections. These data show an overall decrease in Phyllophora spp. biomass at all three sampling sites between March and September 1986. For the March collections, the range of replicate biomass values was greatest at the Manomet Point station (114.57-549.70 g/m2), followed by the Effluent station (106.58-260.53 g/m2), and the Rocky Point station (380.33-478.55 g/m 2 ). Phyllophora spp. made up 54 percent of the total algal biomass at the Rocky Point station, compared with 37 percent at the Effluent station and 27 percent at the Manomet Point station. In September 1986, the range of replicate Phyllophora spp. biomass values was greatest at the Manomet Point station (171.85-291.47 2 g/m ), followed by the Effluent station (73.72-232.90 g/m 2 ), and the Rocky Point station (284.30-335.90 g/m 2 ). In September, Phyllophora spp. made up 53 percent of the total algal biomass at the Manomet Point station, compared with 45 percent at the Rocky Point station and 34 percent at the Effluent station. In March 1986, the Rocky Point station had the highest mean biomass value for Phyllophora spp. at 437.98 g/m 2 . Mean Phyllophora spp. biomass at the Manomet Point station was 265.08 2 g/m , followed by the Effluent station with 205.30 g/m 2 , gy September 1986, mean Phyllophora spp. biomass was still highest at the Rocky Point station (305.47 g/m2), followed by the Manomet Point (234.33 g/m2) and Effluent (123.25 g/m 2
) stations.
Biomass of Remaining Benthic Species (RBS). The algal 62
5---Rocky Point A--Manomet Point 9--Ef fluent 600. g f I\ -l\ l\ / '\ s"- l \' i ; l i \ F
/ \ '
i \
\
~ 400 .
/ I g.
e \ ' \ A ' / A i
'\ t k i / .\
.s g \ ,
N / /
' ,/ N\ / /s i.
g 300 N s '\ ,i
'\ f '\, \ j# j \
\ }E
's *
\
j
--A , 5, 200-
*) \
\.
\
100. k k Chondrus f h h f h f f h h
/ / J' / /~ f /~ / /
Sampling Period Figuro 17. Seasonal Fluctuations in Total Mean Chondrus Biomass at the Monomet Point, Rocky Point, and Effluent Stations during Spring and Fall Sampling Periods for the Collections between September 1982 and September 1986. 63
biomass category designated Remaining Benthic Species is composed of all benthic algae excluding Chondrus crispus, Phyllophora spp., Laminaria spp., and algal epiphytes. Polvides rotundus, Ahnfeltia plicata, Chaetomorpha spp., and Corallina officinalis were important benthic species at all three stations in 1986. Biomass data for the RBS for March 1986 are presented in Table 14. The Effluent station had the highest range of replicate 2 biomass values (1.01-118.24 g/m ), with the Rocky Point station ranked second (3.03-23.04 g/m2), and the Manomet Point station 2 ranked third ( 3.12-16.25 g/m ). The highest mean RBS biomass value 2 occurred at the Effluent station in March (52.97 g/m ), with the 2 Rocky Point and Manomet Point stations equaling 12.45 g/m and 2 9.00 g/m , respectively. ! In September (Table 15), the range of replicate RBS biomass values was again greatest at the Effluent r.ta ti on 2 (5.32-114.11 g/m ), followed by the Manomet Point station g/m ), and the Rocky Point station (0.00-5.69 g/m2), 2 (4.59-34.88 Mean RBS biomass values followed the same relative pattern, with 2 2 69.35 g/m at the Effluent station, 18.29 g/m at the Manomet Point station, and 1.78 g/m at the Rocky Point station. Epiphytic Algal Species. Epiphytic algal biomass values for March and September 1986 are presented in Tables 14 and 15. As for most of the previous years of the study, Phyllophora spp. exhibited a higher degree of epiphytic colonization than C. crispus. It has been hypothesized that the higher biomass of epiphytes associated with Phyllophora spp. is due to the sturdier morphology of this species (BECO, 1986a). In March 1986, mean epiphytic biomass values were highest at the Effluent station I (135.37 g/m2), followed by the Rocky Point station (115.05 g/m2), 2 and the Manomet Point station (90.67 g/m ). These values i represented 24 percent, 14 percent, and 9 percent of the total algal biomass at these three stations. In September 1986, mean epiphytic biomass was again 2 highest at the Effluent station (121.64 g/m ), followed by the 2 2 Manomet Point (103.27 g/m ) and Rocky Point (72.99 g/m ) stations. These values represented a decrease at the Rocky Point and 64
Effluent stations, and an increase at the Manomet Point station, in epiphytic algal biomass from spring to fall in 1986. Total Algal Biomass. Total algal biomass values for March and September 1986 are presented in Tables 14 and 15, total algal
~
respectively. Mean biomass values decreased at all three stations from spring to fall in 1986 (Manomet Point--968.07 2 to 438.93 g/m , Rocky Point--836.57 to 680.94 g/m 2, and Effluent--559.58 to 361.95 g/m2). This decrease from spring to fall was the reverse of the normal seasonal pattern seen at all three stations over the past several years (Figure 18). Chondrus/Phyllophora Colonization Index Study l Colonization *ralues for Chondrus crispus and Phyllophora spp. are presented in Table 16 for March and September 1986. Colonization values are determined for the primary host species (Chondrus and Phyllophora) and are a qualitative measure of the degree of algal epiphytes and invertebrate species present on the host species. A numerical grade from 1 to 4 is given to each 1 replicate sample. These values are determined by comparing the l Chondrus and Phyllophora fractions with a set of four reference { samples previously ranked in order of increasing levels of algal and faunal colonization. Replicate values are summed to determine the colonization value for each station. Colonization values for
- algal and faunal colonizers are then added to determine the Colonization Index values for each station (Table 17).
Data from 1986 continue to indicate that Phyllophora spp. is more heavily colonized by epiphytes than Chondrus. This hcs been the typical observation during most of the past samplings
! and, as was noted earlier, is probably due to the denser frond development of this species compared with Chondrus.
l 65
1000.
/i e00.
j.h j\
/ -
/ \
. j \. / A\
e00. j
\- ,-,'
, \\
/ \.
700 g j g i. s s f
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r 5\
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i \V . /l' l L 400. 1 [ # il 300. 5 -- Rocky Point . 200. 3, Monomei Point W Elituent 100. Total Biomass \
/
f'
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l Sampling Period Figure 18. Seasonal Fluctuations in Total Mean Algal Biomass at the Monomet Point Rocky Point, and Effluent Stations during Spring and Fall Sampling Periods for the Collections between September 1982 and September 1986 66
TABLE 16. COLONIZATION VALUES FOR CHONDRUS CRISPUS AND PHYLLOPHORA SPP. FOR THE MANOMET
' POINT, EFFLUENT, AND ROCKY POINT SUBTIDAL (10' MLU) STATIONS FOR MARCH 1986 AND SEPTEMBER 1986.
A) CHONDRUS CRISPUS Algal Colonization Faunal Colonization Manomet Pt. Rocky Pt. Effluent Manomet Pt. Rocky Pt. Effluent Replicate Mar. Sept. Mar. Sept. Mar. Sept. Mar. Sept. Mar. Sept. Mar. Sept. I 2 1 2 1 2 2 2 2 2 2 1 3 2 2 I I 2 1 2 3 2 1 2 1 1 3 3 1 1 2 4 2 2 1 1 2 2 4 4 1 1 1 1 1 2 1 1 1 '2 1 2 5 3 1 1 I I - 2 1 1 2 1 - @ Tctal 11 5 6 7 6 10 10 7 7 10 6 10 B) PHYLLOPHORA spp. Algal Colonization Faunal Colonization Manomet Pt. Rocky Pt. Effluent Manomet Pt. Rocky Pt. Effluent Replicate Mar. Sept. Mar. Sept. Mar. Sept. Mar. Sept. Mar. Sept. Mar. Sept.
! 3 4 4 4 4 4 3 3 3 3 3 4 2 3 4 3 4 3 4 3 4 3 4 3 4 3 3 4 3 3 4 4 2 4 3 4 3 3 4 3 4 3 4 3 4 3 4 2 4 3 4 5 3 4 2 3 3 4 3 3 3 4 3 4 Tctal 15 20 15 13 17 20 14 IS . 14 19 15 19 O h?Ja'fai"a'tu. .
TABLE 17. COLONIZATION INDEX VALUES FOR CHONDRUS CRISPUS AND PHYLLOPHORA SPP. FOR THE MANOMET POINT, ROCKY POINT, AND EFFLUENT SUBTIDAL (10' MLW) STATIONS FOR MARCH AND SEPTEMBER 1986. Colonization Index Station Mar. Sept. l Chondrus crispas Manomet Point , 21 L2 l l Rocky Point 13 17 : l Effluent 12 20 Phyllophora spp. Manomet Point 29 33 Rocky Point 29 37 Effluent 32 39 J
- 1 i
l l t 1 68
QUALITATIVE TRANSECT SURVEY The qualitative transect surveys of acute nearfield icpact zones were initiated in January 1980 and have been conducted quarterly since 1982. Four surveys of the area were parformed during the 1986 reporting period (March 31, June 19, Scptember 24, and December 17), bringing the total surveys conducted since 1980 to 24. Results of surveys conducted from 1980 through 1983 were summarized in Semi-Annual Report No. 22 to Boston Edison Company (BECO, 1983). A detailed discussion of the March and June 1986 surveys can be found in Semi-Annual Report No. 28 (BECO, 1986b). These results will be summarized here, along with new data from the September and December 1986 surveys. As in previous reports, the denuded zone was defined as baing 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. March 1986 Transect Survey 1 The extent of the denuded and stunted areas immediately offshore from PNPS, as measured on March 31, 1986, is shown in Figure 19. The denuded zone extended approximately 70 meters offshore along the centerline of the effluent discharge canal. As is typical for the transect surveys, the denuded zone was much tore expanded to the left (northwest) of the transect line, ; ronging in lateral extent from 9 to 15 meters. Two prominent l pocks, at 30 m and 50 m, were observed on the northwest side. The right (southeast) portion of the denuded zone was of relatively uniform width, averaging about 4 meters out from the transect line. A large boulder, nearly exposed at mean low water and used as a landmark by our dive team and the Division of Marine l 69
METERS 4 N S 7 Normal Chondrus Growth
-60 i Chondrus !
Stunted - ~ Chondrus J I "' Oenuded Zone 560m2 765m2
-50 o Boulder
-40 o I
E"#8' -
-Chondrus Stunted Zone Chondrus I and i -
-30 Fucus Growth l
-20 '
i . i l i i ! ! I i ! ! i i
. : i. i.
i !
- 10 i i Submerged Jetty
- : i i i i : :
- q lm: l l
Elfluent Canal i 6 6 6 . . i 30 20 10 0 10 20 30 METERS Figure 19. Configuration of Denuded and Stunted Zones for March 31,19'86. 70
Fisheries dive team, is plotted in Figure 19 and serves as a visual fix for the placement of our transect line. The stunted zone in March 1986 extended 81 meters offshore along the discharge centerline. Like the denuded zone, the st'unted zone was m'u'ch broader on the northwest side of the transect line. The southeast portion of the stunted zone was ncrrow, averaging approximately 6 meters out from the transect line. During the qualitative survey in March 1986, algal species present within the Chondrus denuded zone included Ahnfeltia spp., Gracilaria tikvahiae, Corallina officinalis, Enteromorpha spp., and Codium spp. Two of these species (G. tikvahiae and Codium spp.) are characteristic of warm water hcbitats and are only observed near the discharge canal. The total crea encompassed by the denuded zone in March 1986 was 765 m 2 , , 17 percent reduction of the denuded zone as compared with December 1985 (925 m2 ). The stunted zone observed in March 1986 equaled 560 2 m, a 90 percent increase in the size of the stunted zone since Dacember 1985 (295 m 2). The total nearfield impact area for the March 1986 transect survey equaled 1325 m 2 ; 9 percent greater than that measured in December 1985. June 1986 Transect Survey Results of the transect mapping for June 19, 1986 are presented in rigure 20. The denuded zone extended approximately 75 maters along the transect line in June. The southeast extent of this zone ranged from 2 to 6 meters, and the northwest ranged from 5 to 13 meters. The prominent peaks noted on the northwest portion of the denuded zone in March had disappeared in June. The stunted zone observed in June 1986 extended approximately 80 meters offshore along the discharge centerline. The stunted zone ranged in width from 1 meter on the southeast side to 5 meters on the northwest side. 71
METERS N 80 3
-70 Mi Normal Chondrus Growth Chondrus -60<
m> Chondrus Denuded Stunted Zone j Zone 812m 2 g ; 364m2
-50< >
Boulder NChondrus Stunted Zone o <> -
-40<>
I Sparse Chondrus i and
-30 Fucu s Growth I
i
-20 , ,,
! I i i i !
I i i i i ! -- 10 i i Submerged Jetty i i i i i i i i
- p m Elttuent Canal IO IO 1b b 1O $0 $0 METERS Figure 20. Configuration of Denuded and Stunted Zones for June 19.1986.
72
number A of significant observations were made during this survey regarding the denuded zone. Dense mussel populations (Mytilus edulis) were noted by divers, along with patches of bare substrate apparently grazed by the starfish Asterias forbesi. Dateriorating and dead .Gracilaria tikvahiae specimens were observed in the survey zones during the June 1986 transect survey, in contrast to the apparently healthy patches of this species noted in March, codium spp, was still present in June 1986. The total area contained within the denuded zone in June 2 1986 was 812 m , a 6 percent increase compared with March 1986. An 2 additional 364 m were contained within the stunted zone. for a 2 total neartield impact area of 1176 m . This represented a 35 porcent reduction in the size of the stunted zone and an 11 porcent reduction in the size of the total impact area since March 1 1986. September 1986 Transect Survey l The extent of the denuded and stunted zones as measured on September 24, 1986 is shown in rigure 21. The denuded zone observed during the September 1986 transect survey extended offshore approximately 80 meters along the transect'line; the stunted zone extended approximately 81 meters. Although the donuded zone continued to be narrower southeast of the transect line (averaging approximately 5 meters wide), the widths of the two sides were not as dramatically different as has been observed d ring previous mappings (see rigures 19 and 20). In fact, the overall configuration of the impact zones approached a more symmetrical shape than had been seen during most of the previous coppings. The stunted zone observed in September 1986 was { relatively narrow for its full extent around the denuded zone. The prominent peaks in the northwest extent of the denuded zone that wore observed in March and had disappeared in June, were again cbsent in September 1986. Gracilaria tikvahiae was again absent l 73
M rs N S
-7 Chandrus , Normal 1 Stunted Zone - Chondrus Growth 374 m2 Chondrus
, < Oenuded-- 60 6 o , Zone ' 867m2 , i d '
' Boulder /
- 50 i l Chondrus
- Stunted Zone
- 40 > >
4 -- 0 Sparse Grondrus anc h Growth
- 20 .
L Submerged Jetty
- 10 l
"O 'O E! fluent Canat i i i i i i 30 20 10 0 10 20 30 Meters i
Figure 21. Configuration of Denuded and Stunted Zones for September 24, 1986. 1 7' l
1 from the acute impact zones in September 1986. The total area contained within the denuded zone in Scptember 1986 was 867 m 2 , a 7 percent increase since June 1986. The increase was due primarily to the increase in offshore extent of this zone, from 75 meters in June to 80 meters in September. The size of the denuded zone in September 1986 was 25 percent 2 larger than that observed the same time one year earlier (691 m in September 1985), again primarily because of the increased offshore extent of this zone in September 1986. The stunted zone contained an area of 374 m 2 in September 1986, 3 percent larger than the area observed in June 1986. The September 1986 stunted zone was 20 percent larger than that observed in September 1985. 2 The total nearfield impact stea in September 1986 equaled 1241 m , 5 percent larger than in June 1986 and 24 percent larger than in September 1985. 1 December 1986 Transect survey The extent of the denuded and stunted zones as measured on December 17, 1986 is presented in Figure 22. Difficulty in properly setting the transect line due to rough seas and winds resulted in the transect line being angled north of the effluent ecnal centerline and the large boulder that serves as a landmark. Bacause the transect line was not angled as proposed, the procedures for determining rigure 22 were as follows. First, the boundaries of the figure were drawn as usual, with marks at 10
< coter intervals along the transect line (solid line). Next, the angle of the transect line deviation was estimated by assuming the transect was offset 3 meters to the north at 50 meters (3 meters equals the approximate diameter of the large boulder located 50 'l maters along the transect line). A dashed line was then drawn from 0 meters on the transect line through a point 3 meters north of tho 50 meter mark on the transect line. The zone boundaries have bocn plotted as observed distances perpendicular to the dashed i 75 \
Meters N ! Proposed Placement S Estimated Placement of Transect Line of Transect Line On December 17,1986 }
~ l
= 70
'l Chondrus I -- Denuded Zone ig - -so,,\, 753 m2 Chondrus Stunted Zone -
j 421 m3 i -
- 50 "
Normat Sparse Chondrus g Chondrus Growth and g i Egg,yg Growth g Chondrus i 0 1-- 40 i l 1
- j, Stunted Zone i I I
i 1 - 30 o i ' 1xt"5 Patches of new I Chondrus Growth - I I within the Denuded Zone
- i" 10 .'. '
3 l I x5 xxP ,
.- Submerged Jetty "L- to ; i l
I
.p j m I
1 Elfluent Canal i e a i e i 30 20 10 0 10 20 30 Meters 1 Figure 22. Configuration of Denuded and Stunted Zones for December 17, 1986. I ) 76 l
i line and will be reported relative to the proposed placement of the transect line. This will ensure consistency with previous results. In December 1986, the denuded zone extended approximately 75 meters ' offshore along the transect line, a notable decrease since the September 1986 survey. The lateral oxtent of the denuded zone ranged from 4 to 10 meters on both j sides of the transect. The apparent change in the configuration of l the acute impact zone toward a symmetrical shape noted during the Scptember transect survey was even more pronounced during the D3cember survey. Divers reported that, in December 1986, the transition b2 tween the denuded and stunted Chondrus zones was less wall-defined relative to previous surveys. They also reported the presence of scattered patches of apparently new Chondrus growth in the midst of what is typically considered the denuded zone. These patches occurred at 40, 60, and 70' meters along the transect line. This significant observation indicates recovery within the denuded zone in response to the power outage experienced by PNPS since l late March 1986. Laminaria spp. was also observed within the denuded zone in December 1986. In 1984, the sudden appearance of this typically I cold-water alga near the effluent canal was credited as a response to the cessation of thermal discharge from PNPS. Laminaria spp. had never been seen within the acute impact zone prior to June 1984. By June 1985 (six months after PNPS resumed operations) Leminaria spp. was again absent from the area. The reappearance of Leminaria spp. within the acute impact zone during 1986 was, therefore, significant and indicates a return to pre-operational conditions. The total area contained within the denuded zone in 2 Dacember 1986 was 753 m, an area 13 percent smaller than that observed in September 1986 and 19 percent smaller than the area observed in December 1985. The stunted zone in December 1986 was 2 421 m, 13 percent larger than in September 1986 and 43 percent larger than in December 1985. The total nearfield impact area 77
h measured in December 1986 was 11742m , 5 percent smaller than in September 1986 and 6 percent smaller than in December 1985.
'~ CONCLUSION 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 j McGrath (1984) and are typical of shallow, exposed areas in. I western Cape Cod. Bay. The results presented in this report, for d the most .part, agree with their findings. The-rocky substrates characteristic of all three stations are covered with dense macroalgal communities. The algal communities are typically I dominated by two species, Chondrus crispus and Phyllophora spp. j This algal turf has created a' suitable habitat for diverse' faunal 4 communities. Faunal species numbers at all three stations have , ranged from 50 to over 100 species, and total faunal densities 4 6 ! have ranged from 10 to 10 individuals per square meter. These 3 faunal communities are dominated by arthropods, particularly of f the order Amphipoda. The results 'of this study indicate that i faunal species richness, faunal diversity, and-total algal biomass in western Cape Cod Bay exhibit seasonal cycles of low values in ] i spring followed by high values in fall. Faunal densities do not '
- reflect such a cycle and may be more dependent on site specific
! variability than seasonality. 1 i l Examination of the data collected during this study has i indicated a degree of variation in benthic community parameters between the Effluent station and the two reference stations that q can often be attributed to an effect from PNPS operations. This l effect is observed at the quantitative Effluent station, but is f most extreme in a localized area from 0 to approximately 95 meters offshore of the discharge canal (see QUALITATIVE TRANSECT SURVEY). A complete discussion of these impacts is given in Volume 2 of this report. I l 78 e l t
, , - .- = . . .- . .- , - , .. ._ - - - - , . .
l l i. LITERATURE CITED ! Boesch, D.F. 1977. Application of numerical classification in ecological' investigations of water pollution. U.S. Environmental Pro'tection Agency, EPA Report j 600/3-77-033. 114 pp. l Bold, H.C. and M.J. Wynne. 1978. Introduction to the Algal l Structure and Reproduction. Prentice-Hall, Englewood Cliffs, NJ. 706 pp. ~ Boston Edison Co. 1983. Marine ecology studies related to operation { of Pilgrim Station. Semi-Annual Report No.-22. - ! . . 1986a. Marine ecology studies related to-operation of Pilgrim Station. Semi-Annual Report No. 27.
. . 1986b. Marine' ecology studies related to
- operation of Pilgrim Station. Semi-Annual Report No. 28, 4
l Davis, J.D. and R.A. McGrath. 1984. Some aspects of nearshore benthic macrofauna in western Cape Cod Bay. In: Observations on the Ecology and Biology of Western Cape Cod Bay, Massachusetts. Lecture Notes on Coastal and Estuarine Studies. John D. Davis and Daniel Merriman
- (Ed). Springer-Verlag, New York. 228 pp.
i Dawson, E.Y. 1966. Marine Botany An Introduction. Holt, Rinehart and Winston, New York. 371 pp. t ) Grassle, J.F. and W.L. Smith. 1976. A similarity measure sensitive ! to the contribution of rare species and its use in investigations of variation in marine benthic a communities. 0ecologia. 25: 13-22. l Grieg-Smith, P. 1964. Quantitative Plant Ecology. 2nd Ed. 4 Butterworths, Washington, DC. 256 pp. i } Grocki, W. 1984. Algal investigations in the vicinity of Plymouth, ~ l Massachusetts. In: Observations on the Ecology and j Biology of Western Cape Cod Bay, Massachusetts. Lecture i Notes on Coastal and Estuarine Studies. John D. Davis and Daniel Merriman (Ed.). Springer-Verlag, New York. J 228 pp. 1
! Holtshe, J.F. and N.E. Forrester. 1983. Estimating species richness
- using the jacknife procedure. 91cmetrics. 39
- 1-11.
i ! Sokol, R.R. and F. Rohlf. 1969. Biometry. W. H. Freeman and l Company, San Fransisco, CA. 775 pp. 1 I i A 79
--- , . . - , - . _ , - , - . - _ . - - . . , - . , , . ,=_-. - - - . - _ - .,
South, G.R. 1976. A checklist of marine algae of eastern Canada. 1st Revision. Jour. Mar. Biol. Assoc. U.K. 56: 817-843. Taylor, W.R. 1957. Marine Algae of the Northeastern Coast of North America. University of Michigan Press, Ann Arbor, MI. 509 pp. - e 6 80
FINAL SEMI-ANNUAL REPORT Number 29
~
(volume 2 of 2) t: BOSTON EDISON COMPANY on BENTHIC ALGAL AND FAUNAL MONITORING AT THE PILGRIM NUCLEAR POWER STATION January-December 1986 (Impact on Benthic Communities) April 15, 1987 BATTELLE OCEAN SCIENCES 397 washington Street Duxbury, Massachusetts 02332 Battelle is not engaged in research for advertising, sales prorotion, or publicity purposes, and this report may not be reproduced in-full or in part for such purposes.
TABLE OF CONTENTS SECTION PAGE EXECUTIVE
SUMMARY
................................................. 1 INTRODUCTION...................................................... 4 QUANTITATIVE FAUNAL STUDIES....................................... 15 SPECIES RICHNESS....................................... 15 FAUNAL DENSITY......................................... 17 SPECIES DOMINANCE...................................... 21 SPECIES DIVERSITY...................................... 22 4 MEASURES OF SIMILARITY................................. 22 DISCUSSION--FAUNAL STUDIES............................. 31 QUANTITAIVE ALGAL STUDIES......................................... 33 ALGAL COMMUNITY DESCRIPTION............................ 33 ALGAL COMMUNITY OVERLAP................................ 33 , ALGAL BIOMASS.......................................... 34 DISCUSSION--ALGAL STUDIES.............................. 42 QUALITATIVE TRANSECT SURVEYS...................................... 43 CONCLUSION........................................................ 46 LITERATURE CITED.................................................. 50 1 l l i 1 i 1
LIST OF TABLES TABLE PAGE 1 Pilgria Nuclear Power Station Maximum Dependable Capacity Factor (Annual Percentage).................... 12 2 Species Groups Identified by Inverse Cluster Analysis of March 1986 Benthic Faunal Data...................... 28 3 Species Groups Identified by Inverse Cluster Analysis of September 1986 Benthic Faunal Data.................. 29 4 Algal Community Overlap Between Stations for the Period 1983-1986....................................... 35 5 Results of Two-Way ANOVAS for Algal Biomass Parameters, 1986....................................... 38 1 6 Summary of Impacts of PNPS on Benthic Communities...... 47 9 l l I l
)
l l 11
d 1 l f i LIST OF FIGURES FIGURE PAGE 1 Location of Rocky Point, Effluent, and Manomet Point Subtidal (10' MLW) Stations........................... 7 2 Annual PNPS Capacity Factor Plotted for the Period 1972 through 1986..................................... 13 I . 3 Species Richness for the Period September 1979 through September 1986 Plotted with the Maximum Dependable , Capacity Factor (MDC).................................. 16 ! 4 Faunal Densities (M ) for the Period September 1979 through September 1986 Plotted with the Maximum Dependable Capacity Factor (MDC)....................... 18 5 Mytilus edulis Densities (M ) for the Period September . 1979 through September 1986 Plotted with the Maximum ! Dependable Capacity Factor (MDC)....................... 20 6 Shannon-Wiener Diversity (H') for Data Excluding Mytilus edulis Plotted for All Three Stations fron 'l April 1983 through September 1986 Plotted with the Maximum Dependable Capacity Factor.................... 23 a
- 7 Dendrogram Showing Results of Cluster Analysis of September 1986 Data Using NESS and Flexible Sorting.
Shaded Area Highlights Effluent Replicates............ 24 8 Nodal Analysis of Constancy for Species and Replicate
- Groups Determined for the March 1986 Data. Shaded Area
. Highlights Effluent Replicate Group................... 26 i
- 9 Nodal Analysis of Constancy for Species and Replicate Groups Detyermined for the September 1986 Data. Shaded
- Area Highlights Effluent Replicate Group............... 27 ;
i 10 Seasonal Fluctuations in Total Mean Algal Biomass at
- j. the Manomet Point, Rocky Point, and Effluent Stations during Spring and Fall Sampling Periods for the i Collections between September 1982 and September 1986 Plotted with the Maximum Dependable Capacity Factor (MDC)........................................... 36 i 11 seasonal Fluctuations in Total Mean Chondrus Biomass at the Manomet Point, Rocky Point, and Effluent
, Stations during Spring and Fall Sampling Periods for l the Collections between September 1982 and September 1986 Plotted with the Maximum Dependable Capacity Factor (MDC)........................................... 39 iii
I i i LIST OF FIGURES (continued) I FIGURE PAGE 12 Seasonal Fluctuations in Total Mean Phyllophora Biomass at the Manomet Point, Rocky Point, and Effluent Stations during the Spring and Fall Sampling Periods for the Collections between September 1982 and September 1986 Plotted with the Maximum Dependable Capacity Factor (MDC).................................. 40 . 13 Area of Denuded and Stunted Zones in the Vicinity of the PNPS Effluent Canal Plotted with the Monthly PNPS Capacity Factor (MDC) from 1980 through 1986........... 44 14 Results of 1986 Qualitative Transect surveys of PNPS Acute Impact Zone...................................... 45 l T 1 4 1 i i l iv
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LIST OF PLATES PLATE PAGE 1 Effluent plume exiting the PNPS cooling water discharge canal. The effluent plume presents two sources of potential impact on benthic communities: increased ambient temperatures and increased current velocities resulting in benthic scouring.............. 6 3 Aerial view of the Rocky Point and Effluent quantitative sampling stations. The Rocky Point . station is located approximately 0.25 nautical miles ) northwest of the Effluent station and serves as a reference station...................................... 8 3 Aerial view of the Manomat Point quantitative ! sampling station. The Manomet Point Station is ! located approximately 2 nautical miles southeast
- of the Effluent station and serves as a reference j station................................................ 8 4 Diver with underwater writing tablet preparing to i enter water. Diver transact surveys are conducted I quarterly to map the extent of the acute impact zone
. associated with the PNPS effluent canal............... 10 l , 5 Example of the denuded Chondrus zone created by the j PNPS effluent discharge. Chondrus appears only as stunted plants restricted to the sides and crevices of rocks.............................................. 10
- 6 Example of the stunted Chondrus zone created by the
, PNPS effluent discharge canal. Chondrus is found on j the upper surfaces of rocks but is noticeably ! inferior in height, density, and development........... 11 j 7 Example of the normal Chondrus zone. Chondrus density, height, and development are lush and characteristic of the local natural environment....................... 11 4 l v
EXECUTIVE
SUMMARY
l l l Volume 2 of Semi-Annual Report No. 29 presents conclusions regarding the impact of Pilgrim Nuclear Power Station (PNPS) on inshore benthic communities in western Cape Cod Bay, based on examination and comparison of data collected at a surveillance station (Effluent station) and two reference stations (Manomet Point and Rocky Point). PNPS is a base-loaded, nuclear-powered electrical generating unit that uses water withdrawn from Cape Cod Bay to remove heat from the station condensers. The heated water is returned to Cape Cod Bay via a discharge canal, creating the potential for impacts on benthic communities through increased ambient temperature and scouring of the bottom substrate. The current benthic monitoring program is designed to dotect impacts from PNPS through both quantitative and qualitative cathods. Algal and faunal samples are collected from one surveillance and two reference stations semi-annually. Community parameters are calculated by examining these samples, and comparisons are made between the area of highest potential impact (the surveillance station) and the two reference s ta ti on s '. Significant differences between the surveillance and reference stations are scrutinized for possible causal associations with the oporation of PNPS. In addition, diver-conducted observations of tho acute impact area immediately adjacent to the effluent canal provide quarterly data on the extent of this area as a means for essessing increases and decreases in acute effects. Along with surveillance versus reference stations corparisons, the cumulative database associated with this program (14 years) is examined for interruptions in natural, long-term trends that may be connected with the level of PNPS operations. In this regard, the current report focuses on the period from 1983 to 1986, when PNPS experienced its highest and lowest levels of rcoctor output since the Station went on line in 1972. This four l yoor period has provided an invaluable opportunity to assess the 1 1
l time frame during which recovery of certain community parameters can be expected, and the extent of permanent impacts caused by l PNPS. Community analyses detected a distinct difference between the Effluent ' station and reference station faunal communities. Species richness indicated a patchy faunal distribution at the Effluent station along with a clear response over time to maximum and minimum power output reflected in increased species richness at that station compared with the reference stations. Differences in faunal densities among the three stations were not correlated (at p=.05) with PNPS operations, however, and the composition of dominant species at the three stations was relatively similar. Diversity values were typically depressed at the Effluent station relative to the reference stations. Clustering procedures combined with nodal analyses indicated that the overall lack of similarity between the Effluent and reference station faunal communities was primarily due to the effect PNPS exerts on less dominant, pioneering species that move in and out of the impacted area in response to varying levels of PNPS operation. These levels of PNPS operation were more pronounced from 1983 to 1986, resulting in increased instability at the Effluent station compared with the reference stations, and changes in several long-term trends. Algal community studies support our contention that the impact of PNPS on the Effluent station benthic communities primtrily manifested itself in different species composition relative to the reference stations. These differences were reflected in the presence / absence of several less dominant species such as Gracilaria tikvahiae and Laminaria spp. Biomass values for the major algal categories failed to show any patterns, either between stations or over time, that would indicate a significant effect of PNPS at the Effluent station. These data agreed with results of the faunal analyses, and suggest that the impact of PNPS at the Effluent station, although present, was not significant enough to have an effect on the well-established components of the benthic communities typical of the area. This 2 ( _ .. _ _ . _ _ _ _ _ _ _ . _ _ _ - - _ _
was at least-true at distances equivalent to the Effluent station (approximately 120 meters offshore) and greater. Transect survey data from 1983 to 1986 suggested a legged response within the acute impact zones to the dramatic fluctuations in reactor po.wer levels during that period. A period of six to nine months was noted between the causal factor (cessation or resumption of thermal effluent) and associated q rosponse (decrease or increase in size of the acute impact zone). Impacts associated with the thermal discharge of PNPS j continued to be local. The most dramatic impacts were observed within the acute impact zone, measured by the diver transect a surveys, extending approximately 90 to 95 meters offshore. Less sovere impacts were detected a minimum of 120 meters offshore in
; en area beyond the acute effect of PNPS. The combined quantitative and qualitative data from this study support the view of a diminishing impact with increased distance from PNPS.
I I. r l k t i l l 3
FINAL SEMI-ANNUAL REPORT Number 29 (volume 2 of 2) to BOSTON EDISON COMPANY on BENTHIC ALGAL AND FAUNAL MONITORING i AT THE PILGRIN NUCLEAR PONER STATION (Impact On Benthic Communities) January 1986 - December 1986 4 INTRODUCTION The benthic monitoring program being conducted near the Pilgrim Nuclear Power Station (PNPS) began in 1972 and has continued at varying levels to the present time. The objective of this program is to identify and assess the significance of impacts associated with operations of PNPS on the nearshore benthic communities. Introduction of an environmental perturbation has the potential to affect members of these communities because they are relatively unable to migrate away from adverse disturbances. Significant changes in benthic community parameters may, therefore, be correlated with the source of the perturbation. 4 4 l l
PNPS is a base-loaded, nuclear-powered electrical g:nerating unit designed to produce 655 megawatts of energy under full operational conditions. The Station is cooled by water withdrawn from Cape Cod Bay which is used to remove heat from the station condensers. The cooling water is then returned to the Bay via a discharge canal designed to dissipate heat from the water through rapid mixing and dilution. The circulating water pumps produce a flow of approximately 690 cubic feet per second at full operational capacity. Plate 1 shows the, plume created as the offluent leaves the discharge canal. The cooling system at PNPS presents two sources of potential impact on the benthic communities at the mouth of the discharge canal: calefaction of crbient waters and increased current velocities resulting in bonthic scouring. The present design of the benthic monitoring program includes quantitative and qualitative approaches for determining the presence and extent of impacts associated with PNPS. The quantitative studies measure and compare benthic community p0rameters at three stations (rigure 1): a surveillance station located approximately 120 meters 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 n utical miles southeast (Manomet Point station) of the Effluent station. Aerial photographs showing the general locations of these stations are presented in Plates 2 and 3. Algal and faunal community analyses performed on data collected from these stations oro compared for spatial (reference vs. surveillance) and temporal (differences in seasonal trends) variability. Differences that exist between the Effluent and reference stations are then i cxamined for indications of an impact from PNPS at the Effluent station. l Because of its relative distance from the source of porturbation, the quantitative Effluent station was chosen as a site likely to experience an effect from PNPS less severe than that experienced by communities located closer to the effluent discharge canal. The acutely impacted areas immediately offshore 5 1 ?
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I i i' I l Plate 1. Effluent plume exiting the PNPS cooling water l discharge canal. The effluent plume presents two sources of potential impact on benthic j communities: increased ambient temperatures l and increased current velocities resulting in 1 benthic scouring. i 6
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l Subtidal (10'MLW) Stations. l 1 1
fb ,e Plate 2. Aerial view of the Rocky Point and Effluent quantitative sampling stations. The Rocky Point station is located approximately 0.25 nautical miles northwest of the Effluent station and serves as a reference station.
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Plate 3. Aerial view of the Monomet Point quantitative sampling station. The Manomet Point station is located approximately 2 nautical miles southeast of the Effluent station and serves as a reference station. 8
t . the canal (0 to 90 meters from the submerged ends of the canal) ore monitored through qualitative methods. The techniques include diver surveys (Plate 4) to measure the offshore and lateral extent of algal stunting and denudation caused by the effluent discharge. The focus of these observations is the red macroalga Chondrus crispus, a species prevalent throughout western Cape Cod Bay.
- Divers swim along a measured transect line, noting the boundaries
! of the Chondrus denuded (Plate 5), stunted (Plate 6), and normal (Plate 7) zones typical of the acute impact area associated with j the PNPS discharge effluent. Variations in the size of these zones . over time are recorded as a means of determining the area most 1' soverely affected by PNPS operations. Detailed descriptions of all sempling and analysis techniques can be found in Volume 1 of this ! report. Operational conditions at PNPS over recent years have provided an opportunity to assess the degree of impact experienced by the benthic communities and the time frame over which these
- conmunities could be expected to recover if the effect of PNPS l wore removed. Table 1 presents the annual maximum dependable ccpacity factor (MDC) for PNPS from 1972 to 1986. The MDC is a noosure of reactor output that roughly approximates thermal j looding to the marine environment. A maximum value of 100 percent l for the MDC represents the highest allowable change in ambient
; toaperature (32'r AT). Annual MDC values are presented graphically j in rigure 2.
The cumulative capacity factor from 1973 to 1986 has
- boon approximately 53 percent. Closer examination of Table 1 shows j the period from 1983 to 1986 to be of particular interest because l of dramatic swings in power output. In 1983, PNPS experienced a rolatively productive year, with an annual MDC of 80.3 percent.
! Tho following year (1984), PNPS was off-line for a full 12 months, I j rosulting in the lowest annual MDC (0.1 percent) in the history of i tho Station. The outage in 1984 also resulted in reduced scouring off the effluent dischargo canal, with partial circulating water flow from January 1984 and no flow from March 27 to August 13, 1984. This all-time low MDC in 1984 was followed by a record high 9 l
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Chondrus density, height, and development are lush and characteristic of the local natural environment (from BECO,1976). 1 11
TABLE 1. PILGRIM NUCLEAR POWER STATION MAXIMUM DEPENDABLE CAPACITY FACTOR (Annual Percentage). YEAR PERCENT 1986 17.5 1985 84.4 1984 0.1 1983 80.3 1982 56.0 l 1981 58.7 f 1980 51.7 1979 82.5 1978 74.6 1977 45.2 1976 41.5 1975 44.5 i 1974 33.6 1 1973 71.0 I 1972 14.8 i 12
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in 1985 (84.4 percent). The recent up and down trend in PNPS output was continued in 1986, with an annual MDC of 17.5 percent. Outager of some duration began on March 7, 1986, and the Station was completely off-line by the middle of April. Two circulating water pumps operated through February 1986, with only one on line thereafter. The situation at PNPS from 1983 through 1986 has,
.therefore, presented a valuable opportunity to compare the results ,
from two peak operational years (1983, 1985) with results from two years of high potential environmental recovery (1984, 1986). Because the outage that began in April 1986 .was anticipated to last at least through the first quarter of 1987, it was expected that responses within the benthic communities to the lack of thermal effluent and reduced current from PNPS would begin i to be observed in 1986, and that these responses would be similar to those noted during 1984 and.1985 when PNPS experienced record minimum (1984) and maximum (1985) power output. These responses were summarized in Semi-Annual Report No. 27 (BECO, 1986a) and included the following: o A change in the relative rankings of the Effluent and reference stations in terms of species richness; the Effluent station , typically ranked third prior to the 1984 outage, but ranked second in March 1985. o Species diversity values at the Effluent station that were note similar to the reference stations than would be typical if PNPS were operating.
! o A lagged recovery at the effluent acute impact zone resulting in macroalgal growth within the previously denuded Chondrus zones.
o Presence / absence of several species of algae (most noteably Gracilaria tikvahiae and Laminaria spp.), considered indicators of warm-water (G. tikvahiae) and cold-water (Laminaria spp.) habitats, in response to the presence and absence of thermal effluent from PNPS. 14
volume 2 of this Semi-Annual Report summarizes impact findings in relation to the benthic monitoring program. This volume discusses overall trends in the data presented in volume 1 cnd in previous reports in an effort to provide a general view of the effects associated - with PNPS operations on benthic ccmmunities. Volume 2 places particular emphasis on the period from 1983 to 1986 for reasons previously discussed. Volume 2 is intended to provide the reader with a broad impact perspective based on data and results accumulated over the 14 years of the c:nitoring program. QUANTITATIVE FAUNAL COMMUNTIY STUDIES SPECIES RICHNESS Until 1985, species richness values at all three stations sampled during this study had varied according to a seasonal pattern of low species richness in spring followed by high species richness in fall (Figure 3). Additionally, the Effluent station had exhibited depressed species richness in ccmparison with the reference stations. The consistent pattern of reduced species richness at the Effluent station was assumed to be directly related to an effect associated with PNPS operations. As discussed in Semi-Annual Report No. 27 (BECO, 1986a), data from 1985 indicated a lagged response at the Effluent station to the refueling outage of 1984. This response was seen in March 1985 (rigure 3), when the Effluent station ranked second among the three stations for species richness, and in the fact that species richness values at the Effluent station decreased from spring to fall in 1985. The latter observation was assumed to be caused by two factors working together. First, the Effluent station was assumed to have experienced reduced species recruitment from spring to fall compared with previous years. Second, there was a 15
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significant adverse effect on less dominant species that had begun to colonize the Effluent station early in 1985 caused by the ecsumption of PNPS operations. In 1986, species richness values at the Effluent station ware again affected by. the lack of heated effluent being discharged from PNPS. The response to the outage of 1986 was similar to that experienced in 1984-1985, in that a high output y0ar (1985) followed by a low output year (1986) appears to have disrupted the typical, natural pattern of species recruitment at the Effluent station. In March 1986 (immediately after the first prolonged outages in 1986), the Effluent station ranked second crong the stations for pooled species richness and by September 1986, the Effluent station ranked first (rigure 3). The differences between stations for numbers of species were found not significant in March 1986 (p > .05, r=1.9058, df=2/12) and again in September 1986 (p > .05, r=2.1111, df=2/12) by a one-way cnalysis of variance (ANOVA) followed by a Student-Newman-Kouls (SNK) multiple range test. Further examination of rigure 3 shows that the relative ranks of the three stations have changed dramatically over the last four years. It would appear that opportunit.tes for recovery at the Effluent station (outages in 1984 and 1986') have resulted in increases in species numbers there over the time span of 1984-1986. FAUNAL DENSITY l As was reported in Semi-Annual Report 27 (BECO, 1986a), I no distinct seasonal pattern exists for faunal densities at any of l the three stations sampled during this study from 1979 through ' 1986 (rigure 4). It should also be noted that total faunal l densities at the Effluent station do not appear to have exhibited I any noticeable response to the PNPS outages of 1984 and 1986 when ccmpared with the reference stations. The three stations appear to have exhibited similar patterns in total densities over the 17 l
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1983-1986 period. A comparison of data from the reference and surveillance stations does'not indicate an effect on total faunal densities at the Effluent station as the result of PNPS operations. This cbservation is apparent from rigure 4 and was validated by the 1986 data. Differences in faunal densities between the three stations observed during 1986 were tested for significance via a one-way ANOVA followed by a Student-Newman-Kouls (SNK) multiple ecnge test. In March 1986, this procedure detected significantly 1cwer faunal densities at the Manomet Point station compared with both the Effluent and Rocky Point stations (p < .05, F-6.3944, df=2/12). A significant difference was also noted between the Monomet Point and Rocky Point stations (at p=.05) when Mytilus was ecmoved. This procedure also showed a highly significant difference (p < .05, r=50.7668, df=2/12) between all three stations in September 1986. The stations also remained significantly different from one another (at p=.05) with Mytilus counts removed. The relative ranks and degree of difference botween the reference and surveillance stations have been inconsistent during this program and, therefore, indicate the absence of a detectable effect of PNPS at the Effluent station on faunal densities. A significant decrease in Mytilus densities at the [ Effluent station relative to the reference stations was observed from March to September 1986 (rigure 5). It is unclear why this decrease occurred at the Effluent station during a period when PNPS was nonoperational, since conditions during this period would be expected to be most like those found at the reference stations. ) It is possible that Mytilus experienced greater pressure from predation at the Effluent station than was experienced at the coference stations during this period. This, in fact, may be the rocson, since at least one species (Cancer irroratus) known to proy on juvenile Mytilus was observed in significantly higher donsities (at p=.05) at the Effluent station than at either of the i roference stations in September 1986. Whether or not this decrease in Mytilus densities at the Effluent station is related to 'PNPS 19
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9179 12179 &f80 6/80 50/80 1188 4/81 6181 8181 3/82 9/02 &# 8 3 10/ 8 3 3184 9/84 3/85 9185 3/06 9/86 Figure 5. Mytilus edulis Densities (M2) for the Period September 1979 through September 1986 Plotterfl r1fTh Monfmu'~a Dependmbio Capacity Factor IMDC).
cperations (either directly or indirectly) is unknown. SPECIES DOMINANCE Composition of the dominant species at all three stations has remained relatively similar over the period of this otudy, dominance being defined by percent composition. The same species have tended to make up the largest portion (generally > 80 parcent) of the faunal communities from season to season and year to year. These species have been fairly consistent at all three stations. Patterns of species dominance have been tested for significant correlations between stations using Spearman's rank correlation procedure (Zar, 1974). No consistent pattern of correlation between stations has been established that would link PNPS with a significant effect on the dominant species at the Effluent station. For example, in March 1986, the Spearman's procedure noted positive correlations between all three station pairs and indicated that the Effluent vs. Rocky Point, as well as tho Manomet Point vs. Rocky Point, pairings were significant (at p=.05, two-tailed test). However, the Spearman's rank correlation procedure showed no significant correlations between any of the 1 stction pairs in September 1986 (at p .05, two-tailed test), cithough the procedure indicated a negative correlation between tho Effluent station and the Manomet Point station (-0.7).
- The negative association between the Effluent and MOnomet Point stations in September 1986 was primarily due to the i different rank that Caprella penantis assumed at the two stations.
No can conclude from these and similar results in previous years I that the relative ranks of the dominant species have changed over tice, which accounts for the fact that significant correlations botween the stations have not occurred with a regular pattern oither before 1983 or during the period frem 1983 to 1986. The icportant point to be stressed, however, is that based on 21
r observations at the Effluent station compared with the reference stations, faunal species dominance has not been noticeably affected by PNPS operations.
- SPECIES DIVERSITY l
A seasonal pattern of low faunal diversity in-spring l followed by high diversity in fall has been observed at all three stations over the course of this study. This pattern is shown for the 1983 to 1986 period in rigure 6, where diversity values for data with Mytilus edulis counts excluded have been plotted for reasons discussed in volume 1. Figure 6 also.shows that, in l general, the Effluent station exhibits lower diversity values than the reference stations. The two deviations from this last trend (April 1983 and March 1986) do not appear to be related to PNPS operations, and may instead be isolated incidents of reduced diversity at the reference stations, rather than increased diversity at the Effluent station. MEASURES OF SIMILARITY The results of cluster analyses discussed in volume 1 show that the faunal community at the Effluent station is l distinctly different from the communities at the reference stations. This has been the usual observation since the clustering procedures were first employed. Figure 7 presents a typical result of such an analysis (September 1986), where the reference station
; replicate samples show a much higher level of similarity with one another than with samples taken from the Effluent station. As has been stated in previous reports (BEco, 1986a and b), this lack of I
similarity between the Effluent and reference staticus is caused by the. transitional nature of the Effluent station faunal 22
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- 1 : : 2 -i Figure 7. Dendrogram Showing Results of Cluster Analysis of September 1986 Data Using NESS and Flexible Sorling. Shaded Area Highlights Ellluent Replicates.
1 1 community. Since this community reacts in varying degrees to the level of effluent discharge from PNPS, the wide variations in PNPS operation over the past several years (especially 1983-1986) have created periods of high potential impact followed by periods of recovery. The affect of these fluctuations on community structure at the Effluent station is clearly indicated by the clustering tochniques used in this program. In fact, the level of dissimilarity between the Effluent and reference stations noted by these indices has become increasingly more distinct during the , last four years of extreme power fluctuations at PNPS (1983-1986). As described earlier in this report (see Volume 1: DATA ANALYSIS--Analytical Techniques), nodal analysis is a method of relating normal and inverse classifications to help interpret cluster analyses. The method uses two-way tables that show replicate groups (normal) on a vertical side and species groups (inverse) on a horizontal side. We have used this technique to naasure constancy, which is defined as a proportion derived from the number of occurrences of a species group in a replicate group as compared with the total number of possible occurrences (Boesch, 1977). Varying occurrences of species groups identified through cluster analyses provide explanations for dissimilarities between . station groups. Nodal analyses of constancy for the 1986 data are presented in Figures 8 (March 1986) and 9 (September 1986). Raplicate and species groups are based on the cluster analyses discussed in Volume 1, using the Bray-Curtis procedure. Species groups are presented in Tables 2 and 3. A value of 1 resulted when l all species of a species group occurred in all replicates of a replicate group; a value of 0 resulted when none of the species in a species group occurred in any replicates of the replicate group. The nodal analysis performed on the March 1986 data showed that Species Group A was indeed characteristic of the overall ecology near PNPS (Figure 8). Group A exhibited high constancy for both . replicate groups (0.88 and 0.91). The nodal analysis also explained the low degree of similarity between the reference stations (Group 1) and the Effluent station (Group 2).. Figure 8 shows that Species Group B was highly constant among the 25 i
y , h e w g i t a o H r t Y e C y r h d wyr r o _ e g o f N i o e . A T V H ML V d e n S N
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SPECIES GROUPS A F B C D E G nn Q. o 1 0.97 0.63 0.70 0.60 0.60 0.60 0.37 CONSTANCY g 0.7 - 1.0 Very High g 0.5 - 0.7; High Q O.3 - 0.5 Moderate d 9 ' s , s ja - 0.1 - 0.3 Low 2 l0.83 ; j1.00 : j0.6d{ s!0$bilU.Ib jjl sl,.U.2bll ljy}6}j < 0.1 Very Low
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J me Ri i Figure 9. Nodal Analysis of Constancy for Species and Replicate Groups Determined for September 1986 Data. Shaded Area Highlights Effluent Replicate Group.
i TABLE 2. SPECIES GROUPS IDENTIFIED BY INVERSE CLUSTER ANALYSIS OF MARCH 1986 BENTHIC FAUNAL DATA. Group A Group C Idotea ph'osphorea Hiatella arctica Caprella linearis Eulalia viridis Pleusymtes glaber Ischyroceridae juv. Lacuna vincta Group D Mitrella lunata Harmothoe spp. juv. Amphithoe rubricata , Calliopius laevisculus Caprella nr. septentionalis l Corophium spp. Nereis spp. Corophium acutum l Proboloides holmesi-Dexamine thea Group E ' Pontogencia inermis Acarina Amphipoda juv. Caprella penantis Omalogyra atomus Ischyroceridae anguipes Jassa falcata Mytilus edulis Group F Idotea balthica Phyllodoce maculata Corophium insidiosum i Leptonacea sp. A Crepidula plana Nemertea Nereis zonata ' Nereis pelagica Group B 1 Corophium bonelli l Cingula aculeus Margarites helicinus Metopella carina 3 Onchidoris aspe.a Amphipholis squamata Nicotea sp. < Nicolea zostericola Photoe minuta Aivania areolata Eualus pusiolus Strongylocentrotus droebachiensis Caprellidae spp. juv. Ophiopholus aculeata 1 28
-1
)
l l l TABLE 3. SPECIES GROUPS IDENTIFIED BY INVERSE CLUSTER ANALYSIS OF SEPTEMBER 1986 BENTHIC FAUNAL DATA.
=
Gmg A , Gmg 8 Idotea phosphorea Corophium spp. juv. Corophium acutum Crepidula plana Ischyrocerus anguipes Capitella capitata Pontogencia inermis Caprella linearis Group C Jassa falcata . Corophium bonelli Nereis spp. Juv. Corophium insidiosum Strongylocentrotus droebachiensis Group D Asteroides spp. juv. Mitrella lunata Idotea balthica Eulalia spp. Caprellidae spp. juv. Hiatella arctica Phyllodoce maculata Nicolea zostericola Proboloides holmesi Group E Eualus pusiolus Calliopius laevisculus Polycirrus eximius Lacuna vincta Dexamine thea Group F Corophium spp. juv. Caprella penantis Dodecaceria sp. A Acarina
- Mytilus edulis , Group G Cancer irroratus Haliclystis salpinx Pholoe minuta Ophiopholis aculeata Leptonacea sp. A Ncmertea Nassarius trivittatus Pleusymtes glaber ,
Cingula aculeus Margarites helicinus Nicolea spp. Amphipholis squamata Harmothoe imbricta Onchidoris aspera
- Crepidula fornicata Cerastoderma pinnulatum Nereis pelagica e i Ntreis spp.
i l 1 l I l 29 ! 1 i
i reference station replicates (0.83),'but only moderately constant at the Effluent station (0.33). A similar situation existed for
, Species Group r, which was highly constant at the Effluent station (0.93) but only moderately constant at the reference stations
- (0.33).' One member of 'G'roup F (Corophium insidiosum) was a dominant faunal species at the Effluent station in March 1986, but did not occur in appreciable numbers at either of the reference I stations, accounting for the inverse relationship between the two
! replicate groups with regard to Species Group F.
Results of the nodal analysis for September 1986 are { presented in Figure 9. As in previous samplings, a large group of dcminant species (Group A) showed a very high degree of constancy I i at all- three stations (0.97 and 0.83). This observation supports our basic assumption that the composition of dominant species at all three stations is similar, although the relative ranks of these species (based on individual numbers) may be different. Nodal analysis of the September 1986 data also supports the assumption' that the effects of PNPS on the Effluent station communities are focused primarily on the less dominant species. f ! 'For example, noteable differences of constancy-between the two replicate groups in Sept' ember 1986 occurred at Species Groups B i . (0.63 vs. 1.00), E (0.60 vs. 0.20), F (0.60 vs. 0.20), and G (0.37 I vs. 0.80). In terms of percent composition, the species of these i groups contributed little to the total fauna at all three stations. It is important to point out that nodal analyses have consistently indicated that the major differences between the-faunal communities at the Effluent and reference stations is the l composition and density of the less dominant species (BECO, 1985, l 1986a and b). These observations emphasize the significant role that the less dominant species play in influencing overall community structure and the effect PN95 has on them. The fact that the Effluent and reference' stations continue to be dissimilar. during periods of PNPS outages indicates that complete recovery from the effect of PNPS at the Effluent station will require ! longer time periods than have been experienced during recent ! outages. ' i I 30 P
Y* I i DISCUSSION--FAUNAL STUDIES The results of faunal community analyses conducted during 1986 continue to indicate a detectable difference between I the Effluent station a'nd the reference stations. In past reports (BECO, 1986a), we have concluded that.the source of variation , between the faunal components at these stations is a subtle one which mainly affects the less dominant members of the Effluent l
- station communities. The current data support this contention. To j summarize the evidence, species richness values indicate a patchy.
, faunal distribution at the Effluent station along with a clear response over time to maximum and minimum power output (effluent discharged). Differences in faunal densities between the stations are not correlated with PNPS operations, however, and the species l that contribute the majority of the individuals (typically greater ! than 80 percent) to the total fauna at the three stations differ j only in relative rank. Seasonal trends in faunal diversity co-vary at the three stations and usually indicate depressed diversity at
- the Effluent station compared with the reference stations.
f Finally, clustering procedures consistently show a greater degree of similarity between the reference stations when compared with the Effluent station. j Logan and Maurer (1975) have hypothesized that faunal 1 coEmunities in the mouths of thermal effluent canals ere in a j
- i
! "noninteractive, pioneer state." This state is reflected it high low species numbers, and low population dent 'ies l diversity, . caused by intermittently severe environments (i.e., temperature variations, as well as changes in turbidity). The results of the current study indicate that the faunal communities at the Effluent ! station exhibit characteristics somewhat different_ from those j - described by Logan and M'aurer. Although species richness !.s typically depressed at the Effluent station, diversity is also depressed and faunal densities exhibit no consistent relative 31 l
- l. . - . - . .. ,_.,,, - - - - - . . . ,- .- ,
[ h l i 1 1 j rank. Logan and Maurer state that the occurrence of high diversity l in the path of a thermal effluent is probably caused by i recolonization following periods of severe, intermittent environmental change. An example of such a change would be decreased ambient temperatures caused by storms, extreme tides, or plant shutdown. Data from the present study, therefore, seem to indicate that, although there is an effect at the Effluent station, conditions at the station have been relatively stable
! resulting in sustained low diversity compared with the reference j stations. This stability was maintained at.least until 1984, when PNPS experienced a prolonged shutdown.
Under " normal" PNPS operational conditions, the faunal 3 communities at the Effluent station experience different temperature variations annually than are experienced at the i reference stations (i.e., greater ambient temperatures in the summer and winter due to thermal loading), resulting in l ) differences in the community parameters discussed earlier.'These j annual variations were compounded by the extreme maxima and minima of operation experienced by PNPS from 1983 through 1986,. creating environmental variability at the Effluent station on a different j scale than is usually experienced. As has been.noted, the impact i of PNPS at the Effluent station is on the rarer, more transitional species rather than the dominant species. Although the effect of PNPS at the Effluent station is not ' extreme under normal-conditions, erratic PNPS operation during recent years created a prolonged perturbation at the Effluent station in the form of-high power output (maximum impact) followed by no power output (maximum recovery). These fluctuations in power output by PNPS have created a less stably impacted environment at the Effluent station than 4 was experienced prior to 1984, which. explains the changes in relative ranking of the three stations for several of the i parameters measured in this study. i 32
QUANTITATIVE ALGAL COMMUNITY STUDIES
- ALGAL COMMUNITY DESCRIPTIONS l l
Like the faunal communities, the algal communities at the Effluent station are dominated by species that also dominate at the reference stations. However, one indication of the effect of PNPS on algal communities at the Effluent station has been the presence of several less abundant species that do not occur at the reference stations. The most significant of these species is Gracilaria tikvahiae. G. tikvahiae, considered an important indicator of warm-water habitats (BECO,1982), was collected in only one replicate sample from the Effluent station in March 1986, I i and one replicate in September 1986. This decreased occurrence of G. tikvahiae at the Effluent station in 1986 followed normal colonization by this species during 1985 and was expected given the outage experienced by PNPS during 1986. A similar decrease in .G. tikvahiae abundance at the Effluent station was noted in response to the outage of 1984 (BECO, 1986a). Divers conducting qualitative transect surveys at the effluent discharge canal in 1986 also observed a significant decrease in the abundance of G. tikvahiae within the denuded zone, from very abundant in March 1986 to almost completely absent by June 1986. A few scattered patches of G. tikvahiae were still present in September and Dacember 1986, but the positive association between the occurrence-of G. tikvahiae near the Effluent station and the PNPS thermal effluent was again obvious. ALGAL COMMUNITY OVERLAP Algal community overlap in 1986 indicated that the 33
A y e _._. .J J., e.a $- -. - F N'J:- u -~ _ , _ 4., w e...h = # -,.. . $ a_a_ .E i reference station communities -tended to be more similar to one + than to the EffluentT station. another This has been typical ! for most of the previous samplings, yet overlap values for the various station pairings (Manomet Poin't vs. Rocky Point, Manomet i Point 'vs. Effluent, Rocky Point vs. Effluent) are never ' significantly different. Table 4 presents algal community overlap l values between stations for the last.four years. These data show I a relatively homogenous distribution of algal species among all j three stations reflected in similar values in any given month for l all three station pairs. Table 4 also shows that, in April 1983 , l and September 1985, at least one of the surveillance vs. reference 4 station pairings showed a higher degree of similarity (overlap) I i, than the reference vs. reference station pairing. Note that both ! these observations occurred during periods of extremely high power output at PNPS (the average MDC value equaled 90 percent for the s
- 4 six month periods preceding both observations). - However, the increased surveillance vs. reference station values observed in l April 1983 and September 1985 appear to be effects of large-scale trends that occurred in western Cape Cod Bay during these periods rather than effects related to PNPS operations, since the
- accumulated data would indicate that increased PNPS operations would have an effect opposite to what was observed (i.e.,
; decreased similarity between the reference and Effluent stations).
j This suggests that the effect of PNPS on algal species composition at the Effluent station is relatively minor, i j ALGAL BIOMASS Examination of algal biomass data from 1983 through 1985 revealed no clear patterns that could be linked to the refueling outage of 1984 (BECO, 1986a). Changes in total biomass values at. l the Effluent station appeared to be seasonal and unrelated to j impacts caused by PNPS (rigure 10). A consistent pattern of low ] total biomass in the spring followed by high biomass in the fall i j 34 i
TABLE 4. ALGAL COMMUNITY OVERLAP BETWEEN STATIONS FOR THE PERIOD 198bl986. 1983 1984 1985 1986 Apr Oct '~ Mar Sep Mar Sep Mar Sep MP vs. RP 81.0 77.8 76.0 84.0 88.0 65.5 90.9 84.0 MP vs. EF 85.2 67.9 68.0 73.1 77.0 73.1 76.9 70.4 RP vs. EF 81.0 73.0 70.4 71.0 75.0 88.9 80.8 77.8 MP = Manomet Point RP = Rocky Point EF = Effluent 35
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1 Sompting Period Figure 10. Seasonal Fluctuations in Total Mean Algal Blomass at the Manomet Point, Rocky Point, and Effluent Stations during Spring and Fall i l Sampling Periods for the Collections between September 1982 and September 1986 Plotted with Maximum Dependable Capacity Factor (MDC). 36 l i f
i l_ was the trend at all three stations in years prior to 1984. This I pattern continued through 1984 and 1985. Total algal biomass ! values are typically dominated by the presence of Chondrus crispus and Phyllophora spp., an observation that also remained l unchanged in 1984 and 1985. Relative abundance of these two species at the three stations did not follow a clear pattern prior i to the refueling outage in 1984, and no response was evide,nt when l PNPS resumed operations in 1985. Algal biomass data from 1986 were examined for evidence of impacts at the Effluent station and responses to the prolonged j outage in 1986. The five biomass categories (Chondrus crispus, l Phyllophora spp., Remaining Benthic Species, Epiphytic Species, and Total Algal Biomass) were tested by means of a two-way ANOVA i { (Table 5) for significant differences between all three sources of variation (Location, Time, and Location x Time). Significant differences were then examined for possible links to PNPS opsrations. All three sources of variation were highly significant ! (at p=.05) for Chondrus crispus biomass in 1986. The significant f differences noted by this test reflect a decrease in biomass from spring to fall at the Manomet Point and Effluent stations, and , j also significant differences between stations noted by a one-way ) ANOVA procedure performed on the data. The Effluent station j exhibited lower mean Chondrus biomass values than the reference l stations during 1986; this has not been a consistent finding over j the years of .this study (rigure 11), however, and no effect j attributable to PNPS operation can be seen by examining the 1 Effluent station data. l The results of the two-way ANOVA test on Phyllophora j spp. biomass data in 1986 indicated a significant difference ) bstween stations and between sampling seasons, but no significant I differences for the location x time interaction (at p=.05). These I results confirm that, although total Phy11ophora spp. biomass j docreased significantly from spring to fall in 1986, this decrease ! was not significant at any individual station (rigure 12). As was i i noted for Chondrus biomass, there are no discernable patterns of 37
TAILE5. RESULTS OF TWO-UAY ANOVAS FOR ALGAL BIOMASS PARAMETERS,1986. Chondrus crispus: Source of Variation M SS g g Location 2 304023 152012 0.00 Time .. 1 308 % 0 308960 0.00 Location x Time 2 404862 202431 0.00 Error 24 298444 12435 Total 29 1316289 45389 Phyliophora spp.: Source of Variation DF SS MS g Location 2 217407 108704 0.00 Time 1 50147 50147 0.01 i Location x Time 2 12942 6471 0.39 Error 24 159595 6650 i Total 29 440090 15176 Epiphytic Species: ' i Source of Variation DF SS MS g Location 2 7307 3654 0.22 Time 1 1555 1555 0.41 Location x Time 2 3735 1868 0.45 Error 24 54357 2265 i Total 29 66955 2309 Remaining Benthic Species: Source of Variance DF SS MS g 4 Location 2 17403 8701 0.00 Time 1 188 188 0.60 Location x Time 2 983 492 0.50 Error 24 16599 692 Total 29 35173 1213 Total Algal Biomass: 4 Source of Variation DF SS MS g Location 2 502570 251285 0.00 Time 1 648846 648846 0.00 Location x Time 2 209304 104652 0.06 Error 24 818664 34111 Total 29 2179384 75151 i I , DF = Degrees of Freedom i SS = Sum of the Squares MS = Mean of the Squares p = Probability 38 l
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Sampling Period 1 l Figure 11. Seasonal Fluctuations in Total Mean Chondrus Biomass at the Monomet Point, Rocky Point, and Effluent Stations during Spring and Fall Sampling Periods for the Collections between September 1982 and September 1986 Plotted with Maximum Dependable Capacity Factor (MDC). l 1 39
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1 Figure 12. Seasonal Fluctuations in Total Mean Phyllophora Biomass at the Manomet Point, Rocky Point, and Effluent Stations during the Spring and' Fall Sampling ' Periods for the Collections between September 1982 and September 1986 Plotted with Maximum Dependable Capacity Factor (MDC). 40
Phyllophora spp. biomass that would indicate a significant impact associated with PNPS at the Effluent station. l Analysis of the biomass data for the Remaining Benthic Spscies (RBS) by means of a two-way ANOVA indicated a significant j difference (at p=.05) between stations when considering combined i data for 1986. Examination of the mean biomass values revealed that this difference was due to low RBS biomass values at the reference stations as compared with the Effluent station. No significant differences were associated with any of the sources of variation when the 1986 epiphytic data were tested r via a two-way ANOVA. This lack of significance is not surprising l given the inconsistent patterns of difference between stations for the major host categories (Chondrus crispus, Phyllophora spp., j RBS). Because of their dependence on the abundance of a host, biomass values for the epiphytic species tend to mimic major z j trends in host species. When no discernable pattern of station ! doninance is seen in the host species, the same is true for the opiphytic species.
! Figure 10 shows that in March 1986 total algal biomass i ! at the Effluent station continued to show the typical pattern of low values in spring followed by high values in fall, while the reference stations reversed this trend. The atypical increases in l total algal biomass experienced at the reference stations from i September 1985 to March 1986 reflect significantly higher amounts of C. crispus at the Manomet Point station and Phyllophora spp. at j the Rocky Point station (Figures 11 and 12). The differences between stations for total algal biomass in March were not l significant (at p=.05), however, and the decrease in total algal biomass at the Effluent station from September 1985 to March 1986, l
as compared with the increase during the same period at the. ! reference stations, occurred during a period when PNPS was in full l oparation (except for the latter part of March). We conclude from those observations that the change in seasonal patterns of total , algal biomass noted in 1986 were not due to the outage experienced by PNPS during 1986. The fact that similar decreases in total algal biomass from spring to fall in 1986 were experienced at the 41
-- -. _. -- .- . . ~ - .- -
reference stations and the Effluent station.also supports this 7 conclusion and seems to indicate-a change in seasonal patterns ! in western Cape Cod Bay rather than an effect. caused by PNPS.
; DISCUSSION--ALGAL STUDIES ; The results of algal community studies-presented for 1986 support the conclusions drawn earlier for the faunal studies.
! Measures of similarity between stations (in this case, Jaccard's ! Coefficient of Community) indicate a slightly higher degree of I similarity between the reference stations compared with the l Effluent station. This observation is typical for the study, and is caused by the variation of species considered rare in terms of their contributions to the total algal biomass at each station. ! One example of this type of species is Gracilaria tikvahiae, which f occurs only near the effluent canal. However, biomass values for i the acjor algal categories fail to show any patterns, either between stations or over time, that would indicate a significant j effect of PNPS at the Effluent station. These observations are j analogous to those noted earlier in this report for faunal species j richness and faunal densities. We conclude that, like the. faunal
- communities found at the Effluent station,'the algal ~ communities I have experienced a perturbation over time that has affected species composition rather than overall abundance (biomass). More j specifically, the impact-of PNPS on the algal communities'at the Effluent station is reflected in the presence or absence of I several less dominant species. This impact seems to imply an effect on the opportunities available for new species to colonize
- at the Effluent station rather than the reference sites and is
; considered less severe than what might be expected if the Effluent 3 station were located closer to the areas of acute impact (i.e.,
l closer to the mouth of the discharge canal). l i l 42 c
l-i i QUALITATIVE TRANSECT SURVEYS i i l A lagged response within the acute impact zone to the 12-month outage at PNPS during 1984 was reported in Semi-Annual {- ! Report No. 27 (BECO, 1986a). Evidence of this response included'a r ! downward trend in the extent of the total impact area that began l in mid-1984 and continued through mid-1985. Figure 13 presents ! rosults for all qualitative transect surveys since their inception l in 1980. The total acute impact area is plotted along with the ! extent of the denuded zone and the monthly PNPS maximum dependable l capacity factor. The stunted zone is represented by the difference j batween the denuded and total acute impact zones. Between December 1984 and December 1985 the total impact area (denuded and stunted zones combined) was the smallest ever recorded, indicating a pariod of recovery within this area in response to the lack of ! thermal effluent from PNPS. The down swing in areal extent j reversed itself between September and December 1985, showing an ,
! increase in size of the acute impact zone due to.the return to j pre-outage conditions. These results indicated a lagged period of approximately six to nine months between the causal factor-(cessation or resumption of effluent discharge) and associated
- response (decrease or increase in size of the acute impact zone)..
Figure 14 presents the results of the four transect l surveys conducted during 1986. The acute impact zone exhibited a l l response to the power outages that began in March 1986 similar to i that noted in response to the 1984 outage. Return of the acute inpact zone to a size considered typical under normal PNPS , operations continued from 1985 through March 1986 (rigure 13).
! From March through December 1986, the acute impact zone began to docrease in size, again indicative of recovery due to the l
cessation of effluent discharge during the same period. The decrease was not steady, however, with a slight increase in size from June to September 1986. This increase may support the theory of a lagged period of time before uninterrupted recovery within 43 s
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Figure 14. Results of 1986 Qualitative Transect Surveys of PNPS Acute Impact Zone. 45
--.-n - . . - - - - . - .,.
i l 1 l the acute impact zone can begin. l I ! Variations in response to the 1984 and 1986 outages may have been due to the fluctuating operation of the circulating-I waters pumps at PNPS that create scouring within the acute impact I zone. It 'has been hypothesized in the past that the thermal i component of the effluent primarily shapes the-stunted zone, while increased turbidity plays more of a role in shaping the denuded { zone. It is clear from recent data, however, that the independent variability of these two factors probably combine to produce slightly different responses within the acute impact zone each time PNPS goes off-line. It is interesting to note that the denuded zone has varied relatively little throughout the years of this study, never fluctuating more than + 500 m 2 from.1000 m 2 . The denuded zone, therefore, appears to be relatively. stable in terms i of areal extent, exhibiting the most dramatic impacts associated with PNPS. The marked changes in extent of the acute impact zone i is, therefore, due primarily to increases and decreases in the extent of the stunted zone. In fact, the maximum acute impact
]
[ areas recorded (August 1980 and June 1982) occurred during periods ) when the denuded zone was not appreciably larger than during other surveys. The size of the stunted area obviously varies more ' dramatically than the denuded zone and is probably controled by a j j combination of increased temperatures caused by the effluent along l with environmental factors such as available light or storm ! I events. The maxima in 1980 and 1982 may reflect a synergism of effects.- i i , CONCLUSION i i A summary of responses of the benthic communities to ! operations of the Pilgrim Nuclear Power Station, with emphasis on i the period 1983 to 1986, is presented in Table 6. Impacts I associated with the thermal effluent of PNPS continue'to be local. l , Impacts are most dramatic within the acute impact zone, where the i 46 i
TABLE 6.
SUMMARY
OF IMPACTS OF PNPS ON BENTHIC COMMilNITIES. Isapact Study of C; --t Parasmeter PNP 5 1983-1986 Comanents Species Richness Eifluent station ranks last relative Elfluent station ranked second in Outages earing 1984 and 1986 to reference stations indicating March 1983 and March 1986 and first resulted in increases in species impact from PNPS operations. in September 1986. Species richness richness vakses at the Elfluent declined from spring to fall 1985. station. Flucteasting power output destablized conditions and prolonged pioneer state, intro-decing new species at Effluent. Density No detectable pattern overall. No change in response to minimum Relative ranks and degree of (1984,1986) or maximum (1983, difference between the reference 1985) output. and surveillance stations have e been inconsistent over the years of this study, indicating absence of a detectable etlect at the Effhaent station on faunal densities. Quantitative Faunal Species Dominant species relatively constant Composition of doeninant species Dissimilarity between surveil-Studies Dominance in occurence at all three stations, at all alwee stations unaffected lance and reference stations due exhibiting no impact from PNPS from 1983-1986. to ellect on species that contri-operations. bute little to total fauna (by percent composition). Species Diversity Reference stations exhibit closer No significant changes in relative Relatively stable diversity values species diversity with osm another diversities between stations as a at the Elfluent station indicate - than to the Elfluent station indicating result of fluctuating power frosa stable conditions (i.e., sustained impact from PNPS operations. 1983 to 1986. isnpact) with regard to this parameter. Measures of Reference stations more similar to one Reference stations continue to eshibit Chaster analyses reinforce Similarity another than to the Elfluent station higher similarity with one another than - contention that impact of PNPS imlicating impact from PNPS with Effinent station, even eering ' is on 'Yate" species at the operations. perlods of high potent 148 recovery EIfluent staeion. at Elfluent station.
l i l l l TABLE 6. Continued. l Impact Study of Component Parameter PNPS 1983-1986 Comments Community Several species indicative of warm Outages of 1984 and 1986 tyhold Eifluent algal communities, Descriptions habitats have become established at indicator species hypothesis, like the f aunal commimities, are the Eifluent station indicating Gracilaria sikvahiac and distinguishable from reference lenpact frosn PNPS operations. Laminaria spp.both respond to stations by the less dominant maximum and minimum output of PNPS. members of the communities. Quantitative , Algal Community Greater community overlap between No significant change in typical Community overlap indicates a i Studies Overlap reference stations than between the response to PHPS noted from 1983 relatively stable impact at the ! reference stations and the Elfluent to 1986. Effluent station requiring periods station indicating impact from PNPS greater than 12 months for
$ operations. recovery.
Algal Biomass No pattern evident in terms of Algal biomass unaf fected by 1984/ Algal biomass categories, relative algal bionnass between all 1986 outages. representing doeninant algal l three stations. components, do not exhibit a detectable impact from PNPS. t Qualitative Acute Impact Denuded and stunted algal zones Lagged recovery at the elfluent A legged response is logical l Transect Zone created by elfluent discharge. Impact zones in response to outages given the destructive nature of l Survey in 1984 and 1986, the impact in these zones, i l l
l combined effects of increased temperature and turbulence have created an area denuded of algal growth. This area generally extends anywhere from 70 to 80 meters offshore from the discharge , canal and is surrounded by a zone of stunted algal growth. The ! total offshore extent of the acute impact zone has never been more than 95 meters. The Effluent station (approximately 120 meters offshore) is, therefore, beyond the area most severely impacted by PNPS. It is interesting to observe, however, that sensitive I classification procedures consistently indicate a distinct difference between the Effluent and reference stations. As has baen reported, these differences can be explained by the effect ! PNPS has on the less dominant members of the algal and faunal communities at the Effluent station, leaving the dominant components relatively unaffected. The combined quantitative and , i i qualitative data support the view of a diminishing impact with 1 increased distance from PNPS. i l l i 4 4 49
~
LITERATURE CITED Boesch, D.F. 1977. Application of numerical classification in ecological investigations of water pollution. U.S. Environmental Protection Agency, EPA Report 600/3-77-033. 114 pp. Boston Edison Company. 1976. Marine ecology studies related to-operation of Pilgrim Station. Semi-Annual Report No. 8.
. . 1982. Marine ecology studies related to operation of Pilgrim Station. Semi-Annual Report No. 19. . . 1986a. Marine ecology studies related to operation of Pilgrim Station. Semi-Annual Report No. 27 . . 1986b. Marine ecology studies related.to operation of Pilgrim Station. Semi-Annual Report No. 28.
Logan, D.T and D. Maurer. 1975. Diversity of marine invertebrates in a thermal effluent. Jour. Water Poll. Con. Fed. 47:3 515-523. Zar, J.H. 1974. Biostatistical Analysis. Prentice-Hall, Inc., Englewood Cliffs, N.J. 620 pp. 4 i 50
I I k, 4 Ichthyoplankton Entrainment Monitoring at Pilgrim Nuclear Power Station January - December 1986 Volume 1 of 2 (Results) t f l T Submitted to
. Boston Edison Company Boston, Massachusetts by l Marine Research, Inc. ,
l Falmouth, Massachusetts l l
- l l March 13, 1987 Revised April 14, 1987
4-TABLE OF CONTENTS SECTION PAGE I
SUMMARY
l II INTRODUCTION 3 III METHODS AND MATERIALS 4 IV RESULTS AND DISCUSSION A. Ichthyoplankton Entrained 12 B. Lobster Larvae Entrained 32 1 V LITERATURE CITED 34 i APPENDICES A and B (available upon request) i g e
LIST OF FIGURES FIGURE PAGE 1 Entrainment sampling station in PNPS discharge canal. 5 2 Location of entrainment contingency plan sampling stations. 11 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, 1986 (dashed line). Solid lines show high and low values over the 1975-1985 period. 24 i 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, 1986 (dashed line). Solid lines show high and low values over the 1975-1985 period. 28 LIST OF TABLES TABLE I Species of fish eggs (E) and larvae (L) obtained in ichthyoplankton collec*tions from the Pilgrim Nuclear Power Station discharge canal, January-December 1986. 13 2 Species of fish eggs (E) and larvae (L) collected in the PNPS discharge canal from 1975-1986. 19 LIST OF APPENDICES APPENDIX A* Densities of fish eggs and larvae, per 100 m8 of water, recorded in the PNPS discharge canal by species, date, and replicate, January-December 1986.
B* Mean monthly densities and range per 100 m 8 of water for the dominant species of fish eggs and larvae entrained at PNPS, January-December, 1975-1986.
*Available upon request.
ii a
. SECTION 1
SUMMARY
Ichthyoplankton samples were collected from the Pilgrim Nuclear Power Station discharge canal in triplicate twice per month in January and February, weekly from March through September, and again twice each month from October through December. . A total of 37 species were represented in the collections; 17 were represented by eggs; 35 were represented by larvae. During the winter-carly spring spawning season (December-April), egg collections were dominated by relatively small numbers of Atlantic cod, winter flounder, cnd fourbeard rockling. Sand lance, rock gunnel, and grubby accounted for most of the larvae. The late spring-summer season (May-July) produced relatively large numbers of Atlantic mackerel, fourbeard rockling, and labrid eggs as well as winter flounder, radiated shanny, rockling, cackerel, and cunner larvae. Late summer-autumn (August-November) saw rockling, hake, declining numbers of labrids, and Atlantic menhaden 4 dominant among the eggs and northern pipefish, cunner, black sea bass, tautog, and Atlantic herring dominant among the larvae. Comparing 1986 monthly mean densities, per 100 8m of water, over the 1975-1986 period suggests that fourbeard rockling in April and May, Atlantic mackerel in June, and windowpane in May were notably abundant cmong the eggs. Among the larvae rock gunnel in March, sculpin and winter flounder in March and April, rockling in May, mackerel in June, 4 and herring in October appeared to be relatively abundant when compared ! with the same months in past years. Categories which appeared to be 1
relatively scarce in 1986 included larval sand lance in February, American plaice eggs in March and April, larval seasnails in May, larval cunner in l July and August, and larval rockling in July, August, and September. No larval lobsters were taken in 1986. The last time one was taken was in 1982 which represented the ninth since 1974. 1 i l i l I l i , 1 i s i i 1 2 _ , , , . _ - . - - , , . - . - . , - . , . , . , . . - _ _ . , _ _ _ . , 1 - .-..
SECTION II 1 INTRODUCTION This report summarizes results of ichthyoplankton entrainment sampling conducted at the Pilgrim Nuclear Power Station (INPS) discharge canal on a regular basis from January through December 1986. Work was conducted by , Marine Research, Inc. (MRI) for Boston Edison Company (BEco) in compliance with environmental monitoring and reporting requirements under NPDES Permit
- No. 0003557 (U.S. EPA and Massachusetts DWPC).
J J 4
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1 i 1 1 I I 4 i 3
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SECTION III METH'0DS AND MATERIALS r o Entrainment sampling at PNPS fros' January through December _1986 consisted of collecting triplicate samples twice monthly in January, February, October,
~
a ! November, December, and weekly March through September. All samples were col-lected from rigging mounted approximately 30 meters from the headwall of the discharge canal (Figure 1) at low tide during daylight hours. A 0.333-am ! mesh, 60-cm diameter plankton net affixed to this rigging was stressed in the i canal for 6 to 12 minutes depending on the abundance of. plankton and detritus. In each case, a minimum of 100 m3 of water was sampled. Exact filtration volumes were calculated using a General Oceanics Model 2030 digital flowmeter j mounted in the mouth of the net. All samples were preserved in 10% Formalin and returned to the. laboratory i for microscopic analysis. Fish eggs and larvae were identified to the lowest 1 ] distinguishable taxonomic category and counted. Common and scientific names followed Robins et al. (1980). In most cases, species were identifiable. In i i certain cases, however, eggs- particularly in the early stages of development-- could not be identified at the species level in the preserved samples. In: such cases, species were grouped. A brief description of each of these egg l 1 grouptngs in given below.
- Gadidae-Glyptocephalus group (Atlantic cod, Cadus morhua; haddock Melanogrammus aeglefinus; pollock, Pollachius virens; and witch flounder, l
j Glyptocephalus cynoglossus): egg diameters overlap, no oil globule present. Stage III eggs (those containing embryos whose tails have j grown free of the yolk; Ahlstrom and Counts 1955) are separated based i i l 4 a i 4 l
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4 on relative size and pigmentation combinations. Raddock eggs are. difficult to identify until shortly before hatching (late stage III). Because of this, some early stage III haddock eggs may have been iden-tified as cod eggs. This error should be quite small judging from the relatively low numbers of late stage .III haddock eggs and haddock larvae collected at PNPS. The gadidae-Glyptocephalus grouping was not considered necessary in January, February, and December because it is unlikely that witch flounder spawn during these months (Fahay 1983) and haddock spawning is not likely to occur in December nor in peak numbers during January and February (Hardy 1978). All eggs of thn gadidae-Glyptocephalus type were therefore classified as either cod ' or pollock based on differing egg diameters during those three months.
- Enchelyopus-Urophycis-Pepeilus group (fourbeard rockling, Enchelyopus cimbrius; hake, Urophycis spp.; and butterfish, Peptilus triacanthus):
egg and oil globule diameters overlap. Stage III eggs are separated based on differences in embryonic pigmentation. Merluccius-Stenotomus-Cynoscion group (silver hake, Merluccius bilinearis; scup, Stenotomus chrysops; and weakfish, Cynoscion regalis): egg and oil globule diameters overlap. Stage III eggs are separated based on dif ferences in embryonic pigmentation.
- Labridae-Limanda group (tautog, Tautoga onitis; cunner, Tautogolabrus adspersus; and yellowtail flounder, Limanda ferruginea): no oil globule present, egg diameters overlap. Stage III eggs are separated into labridae and yellowtail flounder based on differences in embryonic pigmentation. A high percentage of the two species of labrid eggs are l-l 6
6 l
distinguishable but only with individual, time-consuming measurement (Marine Research 1977a). Labrid eggs are therefore grouped in all three stages of development in PNPS samples.
- Paralichthys-Scophthalmus group (fourspot flounder, Paralichthys oblongus, and windowpane, Scophthalmus aquosus): oil globule and egg diameters as well as pigmentation are quite similar. Separation of these two species, even at stage III, remains uncertain. They are e
therefore grouped in all cases. Eggs of the bay anchovy (Anchoa mitchilli) and striped anchovy (Anchos hepsetus) are easily distinguishable, but their larvae are not. Eggs of these fishes are therefore listed by species while the larvae are listed simply as Anchoa spp. Several other groups of eggs and larvae were not identified to species because adequate descriptions of each species are not available at this time. These groupings are as follows:
- Urophycis spp. - consists of the red hake (U,. chuss), the spotted hake ,
(U. regia), and the white hake (U,. tenuis). Most larvae (and eggs) in this genus collected at PNPS are probably red hake (see summary in Hardy 1978).
- Menidia spp. - consists of the inland silverside (M. beryllina) and Atlantic silverside (M. menidia). Atlantic silverside larvae are probably more likely to occur as far north as Plymouth based on their more northern distribution.
- Ammodytes sp. - No species designation was given the sand lance because considerable taxonomic confusion exists in the literature (see for example Richards et al. 1963; Scott 1968, 1972; Winters 1970; Fahay 7
e 1983). Meyer et al. (1979) examined ' adults collected on Stellwagen Bank and classified them as A,. americanus (=A. hexapterus). This population is.probably the source of larvas entrained at PNPS.
- Prionotus spp. - consists of the northern searobin (P,. carolinus) and the striped searobin (P,. evolans).
-Larval rainbow smelt (Osmerus mordax), cunner (Tautomolabrus adspersus),
and winter flounder (Pseudopleuronectes americanus) were classified into three or four arbitrary developmental stages because these species have been of particular interest in studies at.PNPS. These developmental stages and corresponding length ranges are given below. Rainbow smelt Stage I - from hatching until the yolk sac is fully absorbed (5-7 mm TL). Stage II - from the end of stage I until dorsal fin rays become visible (6-12 mm TL). Stage III - Irom the end of stage II onward (11.5-20 mm TL). Cunner , Definitions of developmental stages are the same as for smelt larvae. Observed size ranges for each stage are: stage I, 1.6-2.6 mm TL; stage II, 1.8-6.0 mm TL; stage III, 6.5-14 mm TL. Winter flounder Stage I - from hatching until the yolk sac is fully absorbed (2.3-2.8 mm TL). Stage II - from the end of stage I until a loop or coil forms in the gut (2.6-4 mm TL). Stage III - from the end of stage II until the lef t eye migrates past the midline of the head during transformation (3.5-8 mm TL). Stage IV - from the end of stage III onward (7.3-8.2 mm TL). 8
t Generally entire samples were examined for fish larvae and all but the most abundant types of fish eggs. When a species was especially abundant, subsamples were obtained with a plankton splitter modified from Matoda (1959; see also Van Guelpen et al. 1982). Pure sample counts of eggs and larvae were used to establish a subsampling regime where the minimum number 1 of specimens considered acceptable increased as the size of an aliquot decreased. (For example, 100 larvae were required for a one-half split; 200 were necessary for a one-quarter split.) In each case all aliquots cere held separately in labeled beakers, the smallest split having been ostablished based on visual observation and preceding samples. Sorting ' proceeded from the smallest aliquot with the most abundant species being l dropped at the end of a particular split if the minimum number requirement was met. Based on the pure sample counts, mean error associated with this regime was 9.7% for eggs, 11.1% for larvae. Coef ficients of variation, l following 10 to 20 replicates each of 1/4 and 1/8 splits with three types of eggs and two types of larvae, ranged from 6.6 to 18.7% (mean = 12.9%). All final counts were converted to numbers per 100 m 3 of water. l In addition to fish eggs and larvae, all samples taken from May through October were examined for larval lobsters (Homarus americanus). Because they have been found to be uncommon at PNPS, no subsampling was done; each sample was examined in its entirety. All entrainment samples were returned to 10% buffered Formalin-seawater , I solutions for storage of not less than three years to conform with NPDES Parmit requirements. l l 9
. _ . . . . _ _ _ . . _ - . _ . _ _ = - _ _ -_ ._ _ _ _ _ . _ - . _ _ _ _ . _ _ _ . _ - - . .
i I When the Cape Cod Bay ichthyoplankton study was completed in 1976, a contingency sampling plan was added to the entrainment monitoring program. l } This plan was designed to be implemented if eggs or larvae of any dominant species. proved to be " unusually abundant" in the PNPS discharge samples.
! The goal of this sampling plan was to determine whether circumstances in l i l 1
the vicinity of Rocky Point were causing an abnormally large percentage of l I' ichthyoplankton populations there to be entrained or alternatively whether i i high entrainment levels simply were a reflection of unusually high population l
- levels in the waters near PNPS. " Unusually abundant" was defined as any I
{ mean density, calculated over three replicates, which was found to be 50% ! 1 ] greater than the highest mean density observed during the same month from M
! 1975 through 1985.
I j The contingency sampling plan consisted of taking additional sets of j triplicates from the PNPS discharge on subsequent dates to monitor the i d temporal extent of the unusual density. An optional offshore sampling ) l regime was also established to study the spatial distribution of the
- species in question. The offshore contingency program consisted 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 ! required authorization from Boston Edison. ; l , 1 1 1 4 i I a 1 l J i i \ 10 1 i C__________ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ - _ _ _ _ _ _ _ _ _ _
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SECTION IV RESULTS AND DISCUSSION A. Ichthyoplankton Entrained Population densities per 100 m 8 of water for each species listed by date, station, and replicate are presented for 1986 in Appendix A (available upon request). The occurrence of eggs and larvae of each species by month is shown in Table 1. Ichthyoplankton collections are summarized below*within the three primary spawning seasons observed in Cape Cod Bay: winter-early spring, late spring-summer, and late summer-autumn. Winter-early spring spawners (December-April). The number of species l taken amounted to 6 in January, 7 in February, and 16 in both March and April. (Because reporting is conducted on a calendar-year basis, December i i 1986 will be discussed below.) Samples contained few eggs since species contributing most to entrainment during the period spawn demersal, adhesive eggs which are not subject to entrainment. Atlantic cod, winter flounder, 4 . and fcurbeard rockling contributed most to the catch. Atlantic cod accounted for all the eggs taken in January and February, 6.2% in March, and 3.0% of the eggs taken in April with respective monthly mean densities per 100 m 8 of water of 0.6, 0.4, 0.4, and 0.2. Winter flounder contributed 93.2% of the eggs in March with a monthly mean density of 6.1 per 100 m 8 of i water and 15.9% of the eggs taken in April with a monthly mean of 1.2 per 100 m8 , Since flounder eggs are demersal and adhesive, their densities in the PNPS discharge canal cannot be considered representative of densities in the waters around Rocky Point. Those which were entrained were probably 12
Table 1. Specios of fish eggs (E) ocd larvae (L) cbtained la ichthy plankton colloetiona from the Pikgria NuclOct Pouer Station diccharga ecnsl. Jn::er.ery-December 1986. Species Jan Feb Mar Apr May June July Aug Sep Oct Nov Dec Atlantic menhaden Bravoortia tyrannus E/L L E/L E/L Atlantic herring Clupea harenaus harennus L L L L L L L Bay anchovy Anchoa mitchilli E E/L L Rainbow smelt Osmerus mordax L Coosefish Lophius americanus E E Fourbeard rockling Enchelyopus cimbrius E E/L E/L E/L E E/L E Atlantic cod Cadus morhua E/L E/L E/L E/L E/L E/L E E Silver hake Merluccius bilinearis E/L E/L E E Atlantic toscod Microgadus tomcod L L C Pollock Pollachius virens L L
- llake Urophycis spp. E E/L E E E/L E/L Silversides Menidia spp. L L ,
Northern pipefish Syngnathus fuscus L L L - L Black sea bass Centropristis striata L L L Weakfish Cynoscion regalis L Wrasses Labridae E E E E E Tautog Tautoga onitis L L L .L L Cunner Tautogolabrus adspersus L L L L Snakeblenny Lumpenus lumpretaeformis L . Radiated shanny Ulvaria sufficurcata L L L L - _ _ - - - . - . - - - - - - - - -- ,-- -- -- ,r., , -
Table 1 (continued). Species Jan Feb Mar Apr May June July Aug Sep Oct Nov Dec Rock gunnel Pholis gunnellus L L L L L Wrymouth Cryptacanthodes maculatus L L Sand lance Ammodytes sp. L L L L L Atlantic mackerel Scomber scombrus E/L E/L E/L E Searobins Prionotus spp. E E E/L E Grubby Hyoxocephalus aenaeus L L L L Longhorn sculpin pl. octodecemspinosus L L L L Shorthorn sculpin fl. scorpius L L Seasnail Liparis atlanticus L L L L Gulf seasnail L., coheni L L Smallmouth flounder Etropus microstomus E E/L Fourspot flounder Paralichthys oblongus L L Windowpane Scophthalmus aquosus E E/L E/L E/L E E Witch flounder Glyptocephalus cynoglossus E/L E/L American plaice flippoglossoides platessoides L E E/L Yellowtail flounder Limanda ferruginea E E E/L E Winter flounder Pseudopleuronectes americanus E/L E/L E/L L llogchoker Trinectes maculatus E Number of species 6 7 16 17 19 20 14 11 12 4 2 2
dislodged from the bottom by currents. Fourbeard rockling did not appear in the collections until April at which time they accounted for 56.4% of the catch with a mean density of 4.3 per 100 m 8 of water. Larval collections during the winter-early spring period were dominated by sand lance, rock gunnel (Pholis gunnellus), and grubby (Myoxocephalus aenaeus). Larval sand lance densities per 100 m 8 increased over the seasonal period avgraging 1.3 in January, 0.1 in February, 9.2 in March, cnd 35.7 in April. These values accounted for 31.2, 1.2, 6.7, and 25.6% of each month's respective total larval catch. Rock gunnel displayed monthly mean densities of 1.1 per 100 m 8 in January, 5.4 in February, 58.4 in March, cnd 8.4 in April, values which accounted for 28.1, 67.2, 42.8, and 6.0% of cach respective month's catch. Grubby did not appear in the collections until February at which time they contributed 10.8% of the month's larvae with a mean density of 0.9 per 100 m' of water. They increased in number in March and again in April showing respective monthly mean densities of 60.0 and 71.9 per 100 m8 of water; percent contribution for these densities was 44.0 and 51.5. Late spring-summer (May-July). A total of 19 species were represented in May 1986, 20 in June and 14 in July. Atlantic mackerel (Scomber scombrus) crd fourbeard rockling dominated early in the period while increasing numbers of i *) tid eggs became dominant through June and July. Atlantic mackerel
- eccounted for 42.1% of all eggs in May,11.9% in June, and 0.2% in July.
I Mean densities amounted to 116.1 per 100 m8 of water in May, 276.7 in June, declining sharply to 1.2 in July. Including eggs categorized as Enchelyopus'- Urophycis-Peprilus, fourbeard rockling accounted for 24.9% of all eggs taken 15
.h 3-4 ! in May, 5.11'of those taken in June.- Since hake eggs became more common in July, the portion of Encholyopus-Urophycis-Peorilus eggs contributed by i i rockling at that time is unclear; all three categories amounted to 4.2% of the total. Mean monthly densities per 100 m 8 of water were 68.5 in May, ^ 119.5 in June, and 21.1 in July (Urophycis included). Combined with the labridae-Limanda group,' tautos and cunner eggs contributed 20.5% of all . eggs j in May,with a monthly mean of 56.4 per 1008 m of water, rising sharply to a , 81.2% in June with a mean density of 1888.6, and 91.0% in July with a mean 1 density of 452.4 per 100 m a. Assuming that most labridae-Limanda eggs were i i in fact labrids appears justified by the relatively small number of yellowtail flounder late-stage eggs and the absence of yellowtail larvas in June and July. Larval collections were dominated numerically by winter flounder, radiated shanny (Ulvaria subbifurcata), and fourbeard rockling in May,
- followed by mackerel, cunner, and rockling in June and July. Monthly mean
! densities of 7.4, 5.8, and 5.5 per 100 m 8 of water were recorded in May for } flounder, shanny, and rockling, respectively, values which represented 30.7, 24.0, and 22.8% of all larvae. In June respective monthly mean densities per 100 m3 of water for mackerel, cunner, and rockling amounted to 113.2, 40.4, and 21.1 while accounting for 57.0, 20.3, and 10.6% of all larvae. Larval monthly mean densities declined sharply in July, mackeret and cunner i j to 0.5 per 100 m 8 , rockling to 0.1 per 100 m 8. Late summer-autumn (August-November). This is a period of declining t f species number - 11 were taken in August, 12 in September, 4 in October, and 2 in both November and December. Egg collections were dominated by rockling, hake, declining numbers of labrids, and Atlantic menhaden i l t i 16 l
,---vw.---4+,-ee,,-w .-,--,r---r,---- --, - ,,,-, m e..--4-,-.,-+,.------,,,,y ,.,,,------,m ,--,..--3-ee m...--,-,,., ---w_.--,+ - .- - - - e .
(Brevoortia tyrannus). Combined with the Enchelyopus-Urophycis-Peptilus grouping, rockling and hake contributed 54.2% of the eggs in August, 24.0% in September, and 61.0% in October; they were absent in November. Mean monthly densities for these eggs were 25.9 per 100 m 8 in August, 10.4 in September, and 0.4 in October. Labrid eggs dropped out of the collections af ter September but accounted for 27.2% of all eggs in August c.nd 0.4% in September with respective mean densities of 13.0 and 0.2 per 100 m 8 of water. Menhaden appeared only during late September and early October but were sufficiently abundant to account for 69.3% of the September e8g catch and 39.0% of the October egg catch; mean monthly densities amounted to 30.0 and 0.3 per 100 m' respectively. Larval collections were quite light throughout this seasonal period particularly after September. Samples contained primarily northern pipefish (Syngnathus fuscus), cunner, black sea bass (Centropristis striata), and tautog. Pipefish contributed 33.7% of all larvae taken in August and 8.1% of those taken in September with monthly mean densities of 0.5 and 0.3 per 100 m8 of water. Cunner accounted for 16.9% of the August larvae and 1.2% of the September larvae; mean densities were 0.2 and 0.05 per 100 m 3 respectively. Black sea bass and tautog like pipefish and cunner were found only during August and September. Mean densities, per 100 m3 of water, amounted to 0.1 and 0.4 in August and 2.1 and 0.3 respectively in September. These values accounted for 10.0 and 28.8% of all larvae in August, 54.3 and 8.9% in September, respectively. Atlantic herring l (Clupea harengus harengus) accounted for half the larvae found in October with a mean density of 0.4 per 100 m3 , and all larvae taken in November with a mean of 1.7 per 100 m' of water. 17 i
. . - - . . _ _ . -. .~~ .. . -. . _- . . . . .
h i The month of December is best considered with the winter-early spring a period. In 1986 only Atlantic cod eggs and Atlantic herring larvae were 1 l found in the two sets' of samples. A mean density of 1.4.per 100 m 8 was l recorded for cod and 0.1 per 100 m 8 for larval herring. . Multi-year comparisons. Mean ichthyoplankton densities meeting the I , i " unusually abundant" criterion did not occur in 1986; therefore no contingency I ,
- . sampling was performed under that program. ;
Table 2 presents a master species list for ichthyoplankton collected
, from the discharge canal at PNPS and indicates the years each species was j
taken from 1975 through 1986. A total of 37 species were represented in the i l 1986 collections which was slightly below the 1975-1985 average of thirty-i eight. No new species was added to the list in 1986, but a hogchoker (Trinectes maculatus) egg was collected for the first time since 1982. j Monthly mean densities per 100 m 8 of water were calculated for-each of j the numerically dominant fish eggs and larvas entrained at PNPS over the i years 1975-1986 (Appendix B, available upon request). Based on these , figures, the following eggs appeared to be abundant in 1986 when compared to 1975-1985 values: fourbeard rockling in April and May, Atlantic mackerel ! t in June, and windowpane in May. Among the larvae, rock gunnel in March, i . i sculpin and winter flounder in March and April, fourbeard rockling in May, 1 Atlantic mackerel in June, and Atlantic herring in October appeared to be relatively abundant when compared with the same months in past years. In i { the case of herring larvae, rockling eggs and larvae, mackeret eggs, and ! sculpin larvae (in March), 1986 mean densities were the highest observed l for the months noted over the 1975-1986 period. In the remaining cases l i 1
Table 2. Species of fish eggs (E) and larvae (L) collected in the Pters discharge canal from 1975-1986. Species 1975 1976 1977 1978 1979 1980 1981 1982 1943 1986 1945 1986 American eel Anguilla rostrata J* J J J J Alewife /blueback herring Alosa spp. L L J L L Atlantic menhaden Brevoortia tyrannus E/L E/L E/L E/L E/L E/L E/L E/L E/L E E/L E/L Atlanttc herring Clupea harengus harengus L L L L L L L L L L L L Anchovy Anchos spp. L L L L L L L L L L tay anchovy A. mischilli E E E E E/L E E Bainbou smelt osserus mordas L L L L L E/L L L L L l Coosefish tophius americanus E/L E E/L E/L E/L L E/L E/L E/L E/L E/L E I Cusk Brosse brosse E/L E/L E/L E/L E/L E E E I Fourbeard rockling Enchelyopus cambrius E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L _ atlantic cod cadus morhua E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L teaJJac k Melanograamus aeglefinus L E/L E/L E/L L L E Stiver hake Merluccius bilinearis E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L Atlantic toscod ' Microgadus toscod L L L L L L L L L Pollock Pollachius virens E/L E/L E E/L E/L E/L L L E/L L leakes Urophycis spp. E/L E/L E/L E/L E E/L E/L E/L E/L E E/L E/L Cusk-eelsleelpouts Ophidiidae-Zoarcidae L Atlantic needlefish Strongylura marina L L Kallifash Fundulus spp. E E ttummachog F. heteroclitus E ! Striped kallifish F. majalis J Salversides Menidia spp. L L L L E/L E/L E E/L L L L Atlantic silversides M. menidia E/L E/L E L teorthern pipefish Syngna t hu s fuscus L l' L L L L L L L L L L l l Slack sea bass Centropristis striata L L L L L L
*J
- Juvenile l . . _ _ _ - _ _ _ - _ _ _ _ _ -
t i Table 2 (coatinued). Species 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 Weakfish Cynoscion reaalis L L L Scup Stenotomus chrysops L L Earthera kangfish Menticirrhus samatilis L L Erasses Labridae E E E E E E E E E E E 'E l Tautog Tautoaa omitis L L L L L L L L L L L L Cunner Tautomolabrus adspersus L L L L L L L L L L- L L Saakebtenay tumpenus lumpretaeformis L L L L L Radssted shanay Ulvaria subbifurcata L L L L L L L L L L L L sock gunnel Pholis aunnellus L L L L L L L L L L L L E rpaout h Cryptacanthodes maculatus - L L L L L L L L Sand lance a w ytes sp. L L L L E/L L L L L L L L l $ Seaboard goby cabiosoma ainsburai L L L Atlantic mackerel Scamber scambrus E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L tutterfish Pepritus triacanthus E/L E/L E/L E E E/L E/L L E/L E/L L 5eatobtas Prionotus spp. E/L E E E E/L E/L E. E/L E/L E/L E/L Sculpen Myomocephalus spp. L L *t L L L L L E/L L E/L L Grubby M. senaeus L L L L L L L L Longhorn sculpin M. octodecesspinosus L L L L L L L Shorthora sculpin M. scorpius L L a. L L L Alligatorfish Aspidophoroides monopterynius L L L Lumpfish Cyclopterus lumpus L L L L E L i Seasnails Leparis spp. L L L L L L L L L L L L Seassail L. atlanticus L L L L L L Culf snailfish L. cobeni L L L L L L Smallmouth flounder Etrepus microstomus L L E- E/L
_.---- _ _ _ _ _ _ . . _ . _ . _ . _ . . _ _ , _ _ . - .. _ - _ _ . . . _ . . . . . _ . . _ - . . .. - . . . . ~ . . - . . . . . . Tahto 2 (contioned). Species 1975 1976 1977 1978 1979 1990 1981 1942 1983 1984 1985 1946 Summer flounder Paralichthys dentatus E/L E/L L Foutspot ilounder P. oblongus E/L E/L L E/L E/L E/L E L L L Windoupone Scophthalous aquesus E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L Watch flounder Clyptocephalus cymentossus E/L E/L E/L E/L E/L E/L E/L E/L E/L E E/L E/L American plance Nippealossoides platessoides E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L Yelloutait flounder timanda ferrusia** E/L E/L E/L E/L E/L E/L E/L E/L E/L E E/L E/L Smooth itounder tiopsetta putnami L E/L Einter flounder pseudopleuronectes americanus E/L E/L L E/L E/L E/L E/L E/L E/L E/L E/L E/L Nogchober Triaectes maculatus E E E E E Northern puffer Sphaeroides maculatus L L
, Number of species
- 41 % 43 35 37 35 40 30 37 34 42 37 l
*For comparative purposes three species of Myomocephalus were assumed for 1975-1978 and tuo species of Liparis for 1975-1980.
l e h
the 1986 mean densities ranked second (rock gunnel, winter flounder, asckeral), or third (windowpane eggs, sculpin larvae in April) over the 12 years. In some cases monthly mean densities observed in 1986 were quite low relative to previous years. These included larval sand lance in February, American plaice eggs in March and April, larval sessnails in May, larval cunner in July and August, and larval rockling in July, August, and September. Among these,1986 means were the lowest observed except for
. cunner in July which ranked eleventh ahead of 1984.
Monthly mean densities per 100 m 8 of water for 1986 are shown in Figure 3 for the eight numerically dominant types of eggs as well as total eggs (all species combined) and in Figure 4 for the ten numerically dominant larval species as well as for total larvae (all species combined). For each species the highest and lowest monthly mean obtained from 1975 through 1985 is shown by solid lines with 1986 monthly means shown by dashed lines. Mean densities for Atlantic menhaden and searobin eggs, rock gunnel, Atlantic mackerel, and winter flounder larvae remained within the range of densities established over past years. Densities for the remaining species ran either above the upper values or below the lower values for certain months. Ichthyoplankton populations sampled over a long time series typically display density variations of one order of magnitude and two orders of magnitude are not unheard of (see Figures 3 and 4). Variations in spawning stock size, food availability, predator densities, and physical variables such as temperature and wind all contribute to the level of observed ichthyoplankton densities. In many cases the particular monthly densities 22
4 i t:hich exceeded all preceding observations at PNPS did so only slightly, cad the same was true for many values which were below all previous cbservations. In those cases where 1986 values were more markedly high or low, we can on1'y suggest that conditions may have been particularly positive or negative for those species during those time periods. I j i l l i I I-l 23
.. . , , , ~ .. -. . - - ~ . . .. . _ . .
t d i j. 2 k i-4 1 i i j Tigure 3. Mean monthly densities per 100 m 8 of water in the 4 PNPS discharge canal for the eight numerically dominant egg species and total eggs,1986 (dashed line). Solid lines show high and low values over i the 1975-1985 period. i Brevoortia tyrannus Scomber scombrus 1 Gadidae-Glyptocephalus Prionotus spp. ~ Enchelyopus-Urophycis- Paralichthys-Scophthalmus , i' Peprilus Hippoglossoides platessoldes i Labridae-timanda Total eggs 1 I 4 e i , I
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B. Lobster Larvae Entrained No larval lobsters were found in the 1986 entrainment samples. The-last time one was taken was in June of 1982, making a. total of nine over the 1974-1986 period. These collections are tabulated as follows: 1983-1986: none found. 1982: 1 larva - stage I on June 14.
.1981: 1 larva - stage IV on June 29..
4 1980: none found. 1979: 1 larva - stage I on July 14. J
,. 1978: none found.
1977: 3 larvae - 1 stage I on June 10; 2 stage'I-on June 17. 1976: 2 larvae - 1 stage I on July 22; I stage IV-V on August 5. 1975: 1 larva - stage I, date unknown. 1974: none found. The lobster larvae collected in 1976 were obtained during a more intensive lobster larvae program which employed a 1-meter net, collecting relatively large sample volumes, in addition to the standard 60-cm plankton net (Marine Research 1977b). Both larvae taken in 1976 were collected in the meter net; $ none were found in the routine ichthyoplankton samples. i The scarcity of larval lobsters in PNPS entrainment samples is most interesting considering that in 1980,918 tons of legal-sized lobsters were landed in Plymouth County by commercial lobstermen with a value of $4.0 million (Lawton et al. 1983). This increased to 1381 tons valued at $6.8 million in 1985 (Hoopes 1986). Offshore neuston sampling conducted in the northwest sector of Cape Cod Bay (Lawton et al.1983; Matthiessen and l- ) 32 i
f I Scherer 1983) also indicated that larvae were not particularly abundant there. To support such a strong fishery it would appear young lobsters must arrive in the Plymouth area from other areas. Sampling around Rocky Point from 1974-1977 showed consi'derably more late-stage larvae than young larvae (Lawton et al. 1983). That, coupled with the prevailing . I counterclockwise Cape Cod Bay currents, suggests that larvae may arrive from the north. Sampling at the mout$ of Cape Cod Bay also* suggests that large numbers of larvae enter Cape Cod Bay from those waters (Matthiessen and Scherer 1983; Matthiessen 1984). Regardless of source, larval lobsters appear to be especially uncommon in PNPS entrainment samples. This is supported by Lawton et al. (1983) who caught only eight larvae in twenty neuston tous near shore around Rocky Point in 1975. In addition to their-suggested scarcity in nearshore waters, larval lobsters' neustonic habits may reduce their probability of entrainment since they would contact the intake skimmer wall which might prevent their passage to the condensers. 9 33
f i SECTION V LITERATURE CITED Ahlstrom, E.H. and R.C. Counts. 1955. Eggs and larvae of the Pacific hake, Merluccius productus. U.S. Fish and Wildlife Service, Fishery Bulletin 56(99):295-329. Fahay, M.P. 1983. Guide to the early stages of marine' fishes occurring in
- the western northern Atlantic Ocean, Cape Hatteras to the southern
, Scotian Shelf. Journal of Northwest Atlantic Fishery Science, Volume 4, 423p. e e. Hardy, J.D., Jr. 1978. Development of fishes of the mid-Atlantic Bight. An . atlas of egg, larval and juvenile stages. Volume II. Anguillidae through syngnathidae. U.S. Fish and Wildlife Service, Biological Services Program. 458p. Hoopes, T.B. 1986. 1985 Massachusetts Lobster Fishery Statistics. Tech-nical Series 20. Massachusetts Department of Fisheries, Wildlife and Environmental Law Enforcement. Division of Marine Fisheries. 20p. Lawton, R., E. Kouloheras, P. Brady, W. Sides, and M. Borgatti. .1983. Distribution and abundance of larval American lobsters, Homarus americanus Milne-Edwards, in the western inshore region of Cape Cod Bay,- Massachu-setts, p. 47-52. Jg1: M.J. Fogarty (ed.), DistributionIand relative abundance of American lobster, Homarus americanus, larvae: New England investigations during 1974-79. NOAA Technical Report NMFS SSRF-775. 64p. Marine Research, Inc. 1977a. Investigations of entrainment of ichthyo-plankton at the Pilgrim Station and Cape Cod Bay ichthyoplankton studies, March-December 1977; twelve-month summary for 1977, Cape Cod Bay ichthyoplankton studies. III.C.2-i. In,: Marine Ecology Studies Related to Operation of Pilgrim Station, Semi-Annual Report No. 11. l Boston Edison Company. i . 1977b. Entrainment investigations and Cape Cod Bay ichthyo-plankton studies, July-September 1976. III.C.1-i-71. In: Marine Ecology Studies Related to Operation of Pilgrim Station, Semi-Annual Report No. 9. Boston Edison Company. Matthiessen, G.C. 1984. The seasonal occurrence and distribution of larval- i lobsters in Cape Cod Bay, p. 103-117. Iri: ' J.J. Davis and D. Merriman (eds.), Observations on the Ecology and Biology of Western Cape Cod Bay, Massachusetts. Springer-Verlag. 289p. and M.D. Scherer. 1983. Observations on the seasonal occurrence, , abundance, and distribution of larval lobsters (Homarus americanus) in Cape Cod Bay, p. 41-46. JBt: M.J. Fogarty (ed.), Distribution and relative abundance of American lobster, Homarus americanus, larvae: New England investigations during 1974-79. NOAA Technical Report. NMFS SSRF-775. 64p. 34
. . ~ , - .. _,. - - - . _ , - - - _ _ - . _ - . - _ - . ., ,
Meyer, T.L.. R.A. Cooper, and R.W. Langton. 1979. Relative abundance, behavior, and food habits of the American sand lance, Ammodytes americanus, from the Gulf of Maine. Fishery Bulletin U.S. 77:243-253. ' Motoda,JS. 1959. Devices of simple plankton apparatus. Memoirs of the Faculty of Fisheries, Hokkaido University 7:73-94. Richards, S.W., A. Perlmutter, and D.C. McAneny'. 1963. A taxonomic study of the genus Ammodytes from the east coast of North America (Teleostei: Ammodytes). Copeia 1963(2):358-377. Robins , C.R. , R.M. Bailey, C.E. Bond, J.R. Brooker, E. A. Lachner, R.N. Lea, and W.B. Scott. 1980. A list of common and scientific names of fishes from the United States and Canada. American Fisheries Society Special Publication 12. 174p. Scott, J.S. 1968. Morphometrics, distribution, growth, and maturity of offsho're sand lance (Ammodytes dubius) on the Nova Scotia banks. Journal of the Fisheries Research Board of Canada 25:1775-1785.
. 1972. Morphological and meristic variation in Northwest Atlantic sand lances (Ammodytes). Journal of the Fisheries Research Board of Canada 29:1673-1678.
)
l Van Guelpen, L., D.F. Markle, and D.J. Duggan. 1982. An evaluation of I accuracy, precision, and speed of several zooplankton subsampling techniques. International Council for the Exploration of the Sea 40:226-236. Sinters, G.H. 1970. Meristics and morphometrics of sand lance in the Newfoundland area. Journal of the Fisheries Research Board of Canada 27:2104-2108. 35
7 APPENDIX A* Densities of fish eggs and larvae, per 100 38 of water, recorded in the PNPS discharge canal by species, date, and replicate, January-December 1986. 1 1
*This Appendix is available upon request.
4 ) _ _ , . , _ _ . . _ . . . , . . . - _ _ . - . _ , _ , _ _ . , , _ ..2. _ , _ , . _ , . . ,_ _u
4
-]
1 1 "1 2 c e O 4- ' APPENDIX B*
- l. -
4
- 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-J 1986.
i, ) *This Appendix is available upon request. 4 4
. - . . _ _ _ - , . . . - , _ - . , _ _ . _ . - - - - - _ - _ . . _ , . - - , . _ . _ , - . - - . . , _ . . - . . . - . ~ . , . . .
e Ichthyoplankton Entrainment Monitoring at Pilgrim Nuclear Power Station January - December 1986 Volume 2 of 2 (Impact Perspective)- Submitted to Boston Edison Company 3oston, Massachusetts by Marine Research, Inc. Falmouth, Massachusetts . March 13, 1987 Revised April 14, 1987 1 i e i i e
.__.m_ r_,.. .._ . , , . , _ . . . . , , . . _
,m. _, - , _
TABLE OF CONTENTS-SECTION PAGE I.
SUMMARY
, 1 II INTRODUCTION 2 III IMPACT PERSPECTIVE A. Contingency Sampling Plan 3 B. General 7 IV LITERATURE CITED 17 i
i
p e . LIST OF FIGURES FIGURE PAGE 1 -Number of. eggs estimated to have been entrained by PNPS in 1986 had it operated at 100% capacity by species or species group including all eggs combined. 8 2 Numbers of larvae estimated to have been entrained by PNPS in 1986 had it operated at 100% capacity by species including all. larvae combined. 9 3 Mean monthly densities, per 100 8m of water, for total eggs entrained at PNPS, April-August 1983-1986. 13 4 Mean monthly densities, per 100 m' of water, for total larvae entrained at PNPS, April-August 1983-1986. 14 a f LIST OF TABLES TABLE 4 1 Ichthyoplankton densities, per 100 m 8 of water, which reached the " unusually large" level in PNPS entrainment samples, 1980-1986. 4 LIST OF PLATES i-l PLATE 1 Plankton net streaming in the discharge canal at Pilgrim Station for the collection of fish eggs and larvae (lobster , larvae are also recorded). A single, six-minute collection can contain several thousand eggs and larvae representing 20 or more species. 3 J i 4 kk 4
SECTION I
SUMMARY
e Ichthyoplankton samples were collected from the Pilgrim Nuclear Power Station (PNPS) discharge canal in triplic' ate twice per month in January cnd February, weekly from March through September, and again twice per conth from October through December. Specific results appear in "Ichthyo-plinkton Entrainment Monitoring at Pilgrim Nuclear Power Station January - Dscember 1986", Volume 1, Results. A general discussion of more impact-related issues are presented here. ichthyoplankton densities meeting the " unusually abundant" criterion dafined under the contingency sampling program did not occur in 1986. Total numbers of eggs entrained in 1986 were estimated at 1,695,815,000 and otal numbers of larvae at 275,503,000. A comparison of April-August ichthyoplankton densities for 1983 through 1986 suggests that the Salt Sarvice Water System pumps alone have less influence on drawing fish larvae and perhaps fish eggs into the intake system than the main seawater pumps. I i l l l 1
SECTION II INTRODUCTION This report covers the results of PNPS ichthyoplankton entrainment sampling primarily in light of potential impact assessment. Discussions are based on results presented in "Ichthyoplankton Entrainment Monitoring at Pilgrim Nuclear Power Station January - December 1986", Volume 1 - Results. Work was conducted by Marine Research, Inc. (MRI) for Boston Edison Company (BECo) in compliance with environmental _ monitoring and o reporting requirements under NPDES Permit No. 0003557 (U.S. EPA and Massachusetts DWPC). The ichthyoplankton sampling net being' deployed in the PNPS discharge canal is shown in Plate 1. , l i l 1 2
1
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~gpY . _w.
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i b
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. . .; ~;r; <nf4 i
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> - __ 1 Plate 1. Plankton net streaming in the discharge canal at Pilgrim Station for the collection of fish eggs and larvae (lobster larvae are also recorded). A single, six-minute collection can contain several thousand eggs and larvae representing 20 or more species. l
SECTION III.
' IMPACT PERSPECTIVE A. ' Contingency Sampling Plan Ichthyoplankton densities meeting the " unusually abundant" criterion, define'd as exceeding by 50% the highest mesa'ensity d over'three replicates recorded during the same month from 1975 through 1985, did'not occur in 1986. . This compares with-four occurrences in 1985, six in 1984, one in 1983, eight in 1982, seven in 1981, and twelve in 1980 (Table 1). No specific events occurred prior'to 1980 primarily because " unusually large" was not precisely defined early in the contingency plan.
In past years it was standard practice for BECo, in consultation with regulatory personnel, to authorize the collection of an additional set of triplicate entrainment samples following the recording of an " unusually-large" density at PNPS. In most cases the additional sets were taken within two days of the original. In all but three cases when this occurred mean densities dropped back to levels within the range established over previous years, indicating that the " unusual" density probably reflected the entrainment of a high density ichthyoplankton patch rather than a more widespread phenomenon. In the three cases where high densities persisted i i (larval rock gunnel April 1982; larval rock gunnel February 1985; larval R 1 Atlantic menhaden June 1981) additional entrainment sampling at about two-day intervals indicated that high densities continued for up to two weeks. ] It appeared in those situations that productivity was generally high relative to previous years. J
- l i
i h f j 4 [ ) , l - - - . - . - . . -- - --. -.__-.. -,--.-
b i~ l' LTable 1.- 'Ichthyoplankton densities, per 100 m of_ water, which reached 8 the " unusually largd'* 1evel in PNPS entrainment samples, 1980-
-1986.
j .
" Unusually large" Previous high Species Month density-(year) density (year)
EGGS . Brevoortia tyrannus June 74.2 (1980) 6.2-(1978) September 1961.9 (1982) 1.4.(1979) 1065.8 (1982) ." . 0.2 (1978) i October 37.8 (1980) Enchelyopus-Urophicis- 30.1-(1979) September 71.1 (1980) i Pepetius Urophycis spp. September 152.8 (1980) 22.3 (1978) Labrid-Limanda & labrid July 12917.0 (1981)' 8116.8 (1975)- Scomber scombrus. May 15261.3 (1985). 572.0 (1980) 1457.6'(1985) i LARVAE ! Brevoortia tyrannus June 7.1 (1981) 4.2 (1980) l 495.9 (1981) 34.7 (1981) October 11.7 (1980) 1.8 (1976) l November 24.3-(1980) 3.2 (1978) Enchelyopus cimbrius August 204.6 (1983). 36.0 (1980) i Urophycis spp. September 105.6 (1984) 22.3.(1981)- Tautogolabrus adspersus June 624.5 (1981) -~378.8 (1977) July 296.5 (1980) 138.5 (1974)- 2162.5 (1981) 296.5 (1980) September 20.3 (1980) 1.5 (1975) l
't Tautoga onitis August 21.6 (1984) 4.1 (1974) ; September 9.2 (1980) 4.8 (1975)
Pholis gunnellus February 19.6 (1984) 7.4 (1975) 13.8 (1984) ~
- 47.5 (1985) 19.6 (1984)
! March 70.2 (1980) 36.9 (1975) 210.5 (1984) 70.2 (1980) 415.2 (1984) 1 April 74.0 (1982) 12.1-(1977)
- - 74.7 (1982) 4 34.0 (1982) 22.4 (1982) l 23.5 (1982) 5
, Table 1 (continued).c
" Unusually large" Previous high Species Month density (year) density (year)-
LARVAE (continued)
. Asunodytes sp. January 31.1 (1980) 13.5 (1975) 104.4 (1985) 31.1-(1980)
Scomber scombrus June 2700.0 (1981) 128.0 (1975) Myoxocephalus spp. March 153.6 (1980) 97.0 (1975)
' April 303.6 (1982) 53.1 (1981)
*" Unusually large" was defined as 50% greater than'the previous high-density observed during the'same month 1975-1985. ~
i 1 1 4 i ( 6
~
B. General e Entrainment of ichthyoplankton by PNPS represents a direct negative anvironmental impact in that fish eggs and larvae pass through the plant in large numbers each day and are subjected to elevated temperatures, rechanical forces, and periodic chlorine. Although survival has been demonstrated for some species of fish eggs at PNPS such as the labrids (45%) (Marine Research 1978, 1982) and among larvae at other power plants (Ecological Analysts 1981), mortality is assumed to be 100% for purposes of PNPS impact assessment. To place fish eggs and larval densities recorded in the PNPS discharge canal, expressed as numbers per 100 m' of water, in some perspective, they were multiplied by plant flow rates over each respective period of occur-rence. This was completed for each of the numerically dominant species as well as total eggs and larvae. Mean monthly densities were multiplied by 17,461.44, the full load flow capacity of PNPS in 100 m3 units per 24-hour day, then by the number of days in each respective month. Values for each conth in which a species or species group occurred were then summed to arrive at a seasonal entrainment value in each case (Figures 1 and 2). Among the eight numerically dominant species, total numbers of eggs entrained ranged from 375,421 for American plaice (Hippoglossoides platessoides) to 1,273,074,092 for the labrid-Limanda group. A total of 1,695,814,892 was obtained for all eggs combined. Numbers entrained for larvae among the ten dominants ranged from 1,831,705 for Atlantic herring (Clupea harengus harengus) to 74,771,632 for sculpin (Myoxocephalus spp.) and 275,503,170 for all larvae combined. These values indicate the 7
MILLIONS OF EGGS ENTRAINED a 5. G 8 3 8 3 8. Species and Occurrence Period Brevoortia tyrannus 16,977,758 l Ng (June-October) % Enchelyopus-Urophycis-Peprilus (April-October) 135,607,289
/{ g Gadidae-Glyptocephalus l 3,769,576 (January-December)
Labridae-Limanda 1,273,074,092 // l (March-September) Scomber scombrus 208,480,339 /p m Pr(tr.notus spp.May-August) l 6,380,410 (June-September)
- Paralichthys-Scophthalmus 36,546,794 ]
(April-September) llippoglossoides platessoides ] 375,421 (April-May) Total Eggs I f,695,814,892
/{
Figure 1. Number of eggs estimated to have been entrained by PNPS in 1986 had it operated.at 100% capacity by species or species group (dominants only) including all egg species combined. The period of occurrence observed in 1986 is also indicated.
MILLIONS OF L ARVAE ENTRelNED
-. -. n n w w a o o o o u o o o Species and Occurrence Period ,
1,831,705 b Clupea harengus harengus - (Jan-April; Oct-Dec) %h Enchelyopus cimbrius n = - =m . : '.: r a 14,293,935 (May-September) E Tautogolabrus adspersus -------m. _ r a _m 21,676,632l , @ i (June-September) Ulvaria subbifurcata c. w a an 5,711,637 l (March-June) -- 39,3 0 2,209 - m = - -- - = - - Pholis gunnellus u - - --= m u - - - (January-May) Ammodytes sp. r e y---- ~ m . . , m 25,08 3,359 -= (January-May) Scomber scombrus e_ . m a r , r z_ a ,, - _ s 31 59,67 7,9 6 3 --- um r --xnm ,- -E (May-July) u ra m m - - --- - g ! Myoxocephalus spp. t = - __ = _ , -n 74,7 71,6 3 2 -a - - -
, (January-April) (
7,281,420 Ltparts spp. e =- _= , (March-June) Pseudopleuronectes americanus- c 1. 1 u- .=-i 11,103,730 (March-June) Total larvae e m - 1275,503,170 - = - - =-m
= < - - -= - -E Figure 2. Numbers of larvae estimated to have been entrained by PNPS in 1986 had it operated at 100% capacity j for each dominant species including all larvae combined. The period of occurrence observed in 1986 is also indicated.
I l tremendous number of eggs and larvae which can pass. th' rough PNPS during a
. year and are presumed to be removed from the population.
The. effects of entrainment on populations of Atlantic menhaden- . (Brevoortia tyrannus), winter flounder (Pseudopleuronectes americanus), pollock (Pollachius virens), cunner (Tautogolabrus adspersus), rainbow. smelt (Osmerus mordax), Atlantic silversides (Menidia menidia'), and , alewives (Alosa pseudoharengus) were assessed by Stone and Webster (1975) using. flow rates for two units at' Pilgrim Station. Using conservative assumptions and ignoring density-dependent compensation among non-entrained ichthyoplankton, no adverse impact on indigenous' populations was predicted to occur. Modeling studies conducted on five species of larval fish which appear to be more abundant in western Cape Cod Bay than in the remainder of the Bay (tautog, Tautoga onitis; seasnail, Liparis spp.; radiated shanny, Ulvaria subbifurcata; sculpin; rock gunnel (Pholis gunnellus) suggested that the percentage of original larval production contributing to entrain-
' ment by PNPS Unit I was less than 1.0 (Marine Research 1978). For twelve additional categories of e'ggs and larvae considered to be more widely distributed in Cape Cod Bay, percentages contributing to entrainment were smaller, the highest being 0.12% (labrid-Limanda eggs).
If entrainment of ichthyoplankton at PNPS represented a serious problem to fish populations in western Cape Cod Bay, the losses might be reflected in the' collections of finfish in the PNPS area. A review of indices of relative abundance based on otter trawl and gill net sampling by Massachusetts Division of Marine Fisheries personnel (Lawton et al. 1985) does not indicate any steady declines among species such as cunner, 10
tcutog, mackerel (Scomber scombrus), cod (Gadus morhua), flounder, and sculpin, which are regularly subject to entrainment at PNPS. However, cven intensive sampling programs are likely to detect only gross population changes at best. Adverse environmental impacts may result from entrainment cnd remain undetected or be attributed to unknown factors or natural _ variation. PNPS was out of service for repairs from April through December of 1986. During this period only one of two main circulating seawater pumps . was operating (flow = 155,000 gpm or 9.78 m2per second compared with 310,000 gpm or 19.56 m 2 per second when the plant operates with two pumps). In 1984 another outage occurred; however both seawater pumps were shut down during the months of April through August. When both seawater pumps were out of service, only about 5000 gpm (0.32 m2 per second) from two Salt Service Water System (SSWS) pumps were available for sampling. Entrainment sampling continued during the shutdown period in 1984 using the standard regime to monitor effects of the relatively low volume SSWS pumps. By sampling for 30 minutes per replicate upstream of the usual location nearer the headwall a minimum of 100 m2 of water continued to be filtered to obtain cach sample. It is interesting to compare 1986 ichthyoplankton densities taken primarily with one seawater pump operating with thost from 1984 when both pumps were shut down and 1983 and 1985 when both pumps were operating. Comparisons were based on the April through August period when all 1984 simpling occurred with only two SSWS pumps on. 11
L When collections were made usirig only the relatively small SSWS pumps, the assumption was made . that plankton woulo continue to be sampled 'in proportion to their abundance in the Rocky Point' area since' larval' fishes,
, 'especially the small ones, show little directional swimming ability and:
! certainly eggs drift passively. As pointed out in the 1985 annual report, r a brief. review of the 1984 data set indicated that the ichthyoplankton densities appeared low during the. April-August period. ..The'1984~ monthly 1 larval means for April, June, and July were all the lowest on record (1975-1986) as were May and July egg means. Mean densities, per 100 m 2 of water, i j on each sampling date from April through August were examined over '1983-q 1986 to compare two years with both seawater pumps operating (1983,'1985), ! one year with.one pump (1986), and 1984 with no seawater pumps operating. 1 Monthly means are shown in Figures 3 and 4. Using a nonparametric, single classification, Kruskal-Wallis test, no significant dif ference (p>0.05) was - l detected for total eggs but a highly significant difference (p<0.01) was detected for larvae. Nonparametric multiple comparisons among years for t' larvae showed no difference between 1985 and 1983 but 1986 and 1984 were i 1 1 1 i significantly different from 1985 and 1983 and from each other. The sum j r i of the ranked values were as follows: ! Eggs Larvae 1985 - 1166 1985 - 1292 l i- 1983 - 987 1983 - 1170 4 1986 - 891 1986 - 801 I i- 1984 - 872 1984 - 566 i H = 1.041 n.s. H = 16.234** i 9 12 4 4
, , , - , , - , - , , . . ,e>---,- ---n. , - -- ,, -.en ,,-,-n,m , ,-.n. ,~n,-,--nn- , - - . ~ . . , , , , , ,
F/SH EGGS
~
l* ts ' I\ : '. . l \l .
\ .
.g j . / n.
/. \
\. /984 w 1000 -
ti I : S
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.x
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x I : .
.\
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\1985 G- I * >- 1 -
H ' 1986
- l. 1983 w
o / a z /
<t I w
E 10 -
$ $ l I l
! APRIL MAY JUNE JULY AUG Figure 3. Mean monthly densities, per 100 8m of water, for total eggs entrained at PNPS, April-August 1983-1986.
-13
10000 - FISH L. ARVAE e
- =
l W . W 1000 -
+-
3 s l m E - O \ 9 \ / x 10 0 - K E / . . . ' . , \' '
. . . . . . . . . 1983
. . . . . .N v .../'
, y t-m ' \
z Lu O / \ g / x ises W / 2 IO ~ s $984 , / l \ l'
, , , , , ,'ase
- APRIL MAY JUNE JULY AUG l
l I
, Figure 4. Mean monthly densities, per '.00 m8 of water, for total larvae-entrained at PNPS,' April-August 1983-1986.
(- . 14
+
. A comparison of the number of species recorded from April' through August over the four years indicates that 1984 samples produced the least with 30; 1983 samples contained 32; 1985, 38; and 1986, 37.
The 1984 larval' collections over the-April-August period were so low as to suggest that local populations were not impacted in similar propor-tion by the SSWS pumps as by the circulating seawater pumps. Perhaps the relatively low flow of the small pumps had very limited influence on drawing larvae into the intake area, the vast majority of them remaining within the prevailing Cape Cod Bay currents. The fact that 1986 larval dsnsities when one pump operated ranked between 1985, 1983, and 1984 suggests o direct relationship between pump capacity and entrainment. These results l could reflect primarily a physical effect among free-floating larvae or an active ability among larger larvae to avoid varying flow rates. For example, i at some point water entrained by the PNPS intake separates from the prevailing Cape Cod Bay current and enters the intake area. The area over which the , flow separation occurs is presumably more widespread and the action more forceful (the velocity higher) when two seawater pumps operate than when only one seawater pump operates or two SSWS pumps operate. Passive larvae and eggs should be entrained in proportion to their abundance but more active larvae may swim, to the extent of their ability, to remain within the Cape
~ Cod Bay water mass.
i Although no significant difference was detected among eggs, it it interesting that they did rank out in the same order as the larvae. There _ eppeared to be particularly little difference between the one seawater pump year (1986) and the zero seawater pump year (1984). If population densities ( 15
i were similar between those two years, then it would appear that passive particles such as eggs were sampled in proportion to their abundance by the two SSWS pumps as we originally presumed. It is important to keep in mind that any comparisond based on different pump capacities are made without knowledge of population levels around Rocky Point. The rank order observed could be due solely to differences in production among the four years. Precise information on the vertical flow gradients in the PNPS intake with various' pumps in operation as well as precise vertical distribution information for eggs and larvae in the ( area is not available. It is possible that the SSWS pumps, for example, , draw water from a portion of the water column where ichthyoplankton are less abundant. The large-capacity seawater pumps presumably draw water over larger areas, vertically as well as horizontally, and increase the probability of entrainment. 1 i 1 1 1 1 i .i
- 16 I
1 SECTION IV IITERATURE CITED'
. Ecological' Analysts, Inc. 1981. Entrainment survival studies. Research Report EP 9-11, submitted to Empire State Electric Energy Research Corporation, New York.
Lawton, R.P., C. Sheehan, V. Malkoski, S. Correia, and M. Borgatti. 1985. Annual report on monitoring to assess impact of Pilgrim Nuclear Power Station on marine fisheries resources of western Cape Cod Bay. Project Report No. 38 (January-December 1984). III.A i-80. Jgt: Marine Ecology Studies Related to Operation of Pilgrim Station, Semi-Annual Report No. 25. Boston Edison Company.
! Marine Research, Inc. 1978. Entrainment investigations and Cape Cod Bay ichthyoplankton studies, March 1970-June 1972 and March 1974-July 4
1977. Volume 2, V.1 i-44. jg1: Marine Ecology Studies Related to j Operation of Pilgrim Station. Final Report. July 1969-December 1977. Boston Edison Company.
. 1982. Supplementary winter flounder egg studies conducted at Pilgrim Nuclear Power Station, March-May 1982. Submitted to Boston Edison Company. o4 p .
Stone and Webster Engineering Corporation. 1975. Demonstration Pilgrim Nuclear Power Station Units'I and 2, Boston Edison Company, Boston, Massachusetts. 1 l 4 17
' IMPINGEMENT OF ORGANISMS AT PILGRIM NUCLEAR POWER STATION (January - December 1986) l Prepared by: _
Robert D. Anderson Senior Marine Fisheries Biologist 4 ) , April 1987 Regulatory Affairs and Programs Boston Edison Company I
3 Herring m.n n , Alewife a5Ih5$fjh5[jhii,!,!!U!?i" ""' Smelt Canner Most commonly
- - y [sbarrisa impinged species I
i
-TABLE OF CONTENTS Section Title Page-1
SUMMARY
~ 1 2- INTRODUCTION' 2-3 METHODS AND MATERIALS 5 4 RESULTS AND DISCUSSION 7 4.1 Fishes 7
't 4.2 Invertebrates 19 4.3 Fish Survival 21 S CONCLUSIONS 23 6 LITERATURE CITED 25 l l l-l i
l LIST'0F FIGURES Figure Page 1 Location of Pilgrim Nuclear Power Station 3 2 Cross-Section of Intake Structure of Pilgrim 4 Nuclear Power Station 3 Trends of Intake Water Temperature, and Number 12 of Fish Captured by month from Pilgrim Station Intake Screens for the Five Most Abundant Species Collected, January-December 1986 I LIST OF PLATES Plate 1 The 300 foot long Pilgrim Station, concrete screenwash sluiceway is molded from 18" corrugated metal pipe, and meanders over breakwater rip rap. 2 Fish survival testing is done at the end of the slutteway where it discharges to ambient temperature intake waters. 11
a LIST OF TABLES Table Page 1 Monthly Impingement for All Fishes Collected From 8 Pilgrim Station Intake Screens, January-December 1986 2 Species, Number, Total Length (mm), Weight (gms) 9 and Percentage for All Fishes Collected From Pilgrim Station Impingement Sampling, January-December 1986 3 Annual Impingement Collections (1977-1986) for 10 the 10 Most Abundant Fishes From Pilgrim Station Intake Screens During January-December 1986 4 Approximate Number and Cause for Most Notable Fish 14 Mortalities at Pilgrim Nuclear Power Station, 1973-1986 5 Impingement Rates per Hour, Day and Year for All 15 Fishes Collected From Pilgrim Station Intake Screens During January-December 1986, Assuming 100% Operation of Pilgrim Unit I 1 I 111
Table- Page 6 Impingement Rates Per Hour, Day and Year for -16 All Fishes Collected From Pilgrim Station Intake Screens During 1973-1986, Assuming 100% Operation of Pilgrim Unit 1 7 Monthly Means of Intake Temperatures (*F) Recorded 18 During Impingement Collections at Pilgrim Nuclear Power Station, 1977-1986 8 Monthly Impingement for All Invertebrates Collected 20 From Pilgrim Station Intake Screens, January-December 1986 9 Survival Summary for the Fishes Collected During 22 Pilgrim Station Impingement Sampling, January-December 1986. Initial, One-Hour and Latent (56-Hour) Survival Numbers are Shown Under Static (8-Hour) and Continuous Wash Cycles Iv
f SECTION I
SUMMARY
Fish impingement rate averaged 1.26 fish / hour during- the period January-December 1986, which is the highest rate in the last five years despite only one circulating water pump operating most of the year. . Atlantic herring (Clupea harengus_ harengus) accounted for 33.9% ,of the fishes collected. Rainbow smelt (Osmerus mordax), Atlantic menhaden (Brevoortia tyrannus), win-ter flounder (Pseudopleuronectes americanus) and Atlantic silverside (Manidia i menidia) accounted for 27.3, 11.1, 7.5 and 4.3%, respectively, of the fishes impinged. Peak impingement months were August and ~ November when the Atlantic herring and rainbow smelt, respectively, were most represented. Initial im-
- pingement survival for all fishes from static screen wash collections was ap-proximately 19%, and from continuous screen washes 60%. Delayed mortality data was not available do to failure of the screenwash survival pumps, sam-pling in the screenhouse or lost fish during portions of 1986.
At full-load yearly (January-December) operation of Pilgrim Nuclear Power Station (PNPS) the estimated impingement was 11,075 fishes (326 lbs.). The PNPS capacity factor was 17.5% during 1986. i i The collection rate (no./hr.) for all invertebrates captured from January-December 1986 was 1.91+. Blue mussel (Mytilus edulis), sand shrimp (Crangon i septemspinosa) and horseshoe crab (Limulus polyphemus) were most numerous, accounting for approximately 71.6, 6.7 and 5.1%, respectively, of' the inverte-brates impinged. Mixed species of algae collected on intake screens amounted i to 2,080 pounds. I l
SECTION 2 4 INTRODUCTION 1 Pilgrim Nuclear Power Station (lat. 41'56' N, long. 70*34' W) is located on the northwestern shore of Cape Cod Bay (Figure 1) with a licensed capacity of 655 MWe. The unit has two circulating water pumps with a capacity of ap- ! proximately 345 cfs each and five service water pumps with a combined capacity of 23 cfs. Water is drawn under a skimmer wall, through vertical bar racks spaced approximately 3 inches on center, and finally through vertical travel-ling water screens of 3/8 inch wire mesh (Figure 2). There are two travelling water screens for each circulating water pump. r This document is a report pursuant to operational environmental monitoring and reporting requirements of NPDES Permit No. 0003557 (USEPA) and No. 359 (Mass.
! OWPC) for Pilgrim Nuclear Power Station, Unit I. The report describes im- ! pingement of organisms and survival of fishes carried onto the vertical trav-elling water screens at Unit I. It presents analysis of the relationships ; I among impingement, environmental factors, and plant operational variables. ! The report is based on data collected from screen wash samples during January-l December 1986.
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SECTION 3 METH005 AND MATERIALS I Three screen washings each week were performed from January-December 1986- to provide data for evaluating the magnitude of marine biota impingement. The total weekly collection time was 24 hours (three separate 8-hour periods: j . morning, afternoon and night). Two collections represented dark period sam-pling,and one represented light period sampling. At the beginning of each collection period, all four travelling screens were washed. Eight hours ; i later, the screens were again washed (minimum of 30 minutes each) and~all.or-ganisms collected. When screens were being washed continuously, one hour col- ) lections were made at the end of the regular sampling periods, and they repre-sented two light periods and one dark period on a weekly basis. 1 i
- Water nozzles directed at the screens washed impinged organisms and debris l Into a slutceway that flowed into a trap. The original trap was made of gal-1 l vanized screen (3/8-inch mesh) attached to a removable steel frame and it col-i lected impinged biota shortly after being washed off the screens. A _second trap was designed and used for sampling, in conjunction with sluiceway sur-vival studies, consisting of a section of half 18" corrugated metal pipe with
- 3/16-inch nylon, delta mesh netting attached. Impinged blota sampled by this
, trap were collected at the end of a 300' slutceway where initial, one-hour and ! latent (56-hour) fish survival were determined for static (8-hour) and contin-l l uous screenwash cycles. Plates I and 2 provide views of the beginning and end of this slutceway structure which was constructed in 1979.
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Variables recorded for organisms were total numbers, and individual total lengths (mm) and weights (gms) for up to 20 specimens of each species. A ran-dom sample of 20 fish or invertebrates was taken whenever the total number for-a species exceeded 20; if the total collection for a species was less than 20,' all were measured and weighed. Field work was conducted by Marine Research, Inc. Intake seawater temperature, power level output, tidal stage, number of circu-lating water pumps in operation, time of day and date were recorded at the time of collections. The collection rate (#/ hour) was calculated as number of organisms impinged per collecting period divided by the total number of hours in that collecting period. All common and scientific names in this report follow the American Fisheries Society (1980) and Smith (1964).
i i SECTION 4
~
RESULTS AND DISCUSSION l 4.1 Fishes-i
- In 806 collection hours,1,019 fishes of thirty-three - species (Table 1) were I collected from . Pilgrim Nuclear Power Station intake screens during January-l l December 1986. The collection rate was 1.26 fish / hour. This annual im-pingement rate is the highest since 1981 - despite only one circulating' water l pump operating for most of 1986. Atlantic herring (Clupea harenaus harenaus) i
) t:as the most abundant species in 1986, accounting for 33.9% of all fishes col-l 1ected (Table 2). Rainbow smelt (Osmerus mordax), Atlantic menhaden , l (Brevoortia tyrannus), winter flounder (Pseudopleuronectes -americanus), and Atlantic silverside (Menidia menidia) accounted for 27.3, 11_.1, 7.5 and 4.3% l of the total number of fishes collected and identified to lowest taxon. Atlantic herring occurred predominantly in monthly samples from June-August. l j Hourly collection rates per month for Atlantic herring ranged from.0 to 2.71. i i i Atlantic h rring impinged in August accounted for 66.5% of all this species j captured in impingement collections from January-December 1986. They averaged , 90 mm total length aad 5 grams in weight. Their impingement indicated no re-
- lationship to tidal stage or diel factors. It is unusual for them. to dominate the impingement catch, as happened previously in 1976, although a review of fish surveillance overflight data shows them to be prevalent in the Cape Cod Bay area during the colder months. Atlantic herring showed an annual impinge-1
- ment of several times as many specimens in 1986, for comparable collecting hours, than in 1977-1985 (Table 3).
_ _ _ _ _ _ _ - - . _ , . _ . _ . , _ _ _ _ - . _ . . _ . . _ _ . _ - = . _ . _ . . _ _ . . _ _ _ - . . - _ . . . . . . _
Table 1. Monthly Impingement Fcr All Fishes Collected from Pilgria
- i Station Intake Screens, January-Deccaber 1986 i
Species Jan. Feb. March Aprl) May June July Aug. Sept. Oct. Nov. Dec. Totals Atlantic herring I 52 62 230 1 346 Rainbow smelt 2 247 29 278 T Atlantic menhaden 2 8 24 56 23 113-Hinter flounder 1 9 2 1 4 4 6 49 76 Atlantic silverside 10 24 2 1 1 6 44 Grubby 5 1 2 5 3 3 3 1 3 4 30 ~ Cunner 1 8 5 1 4 5 1 1 26-Alewife I 11 1 12 25 Atlantic tomcod 2 1 1 1 3 5 3 16 Hindowpane 1 3 5 9 Bay anchovy 1 3 1 5 Blueback herring 1 1
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3 5' - Lumpfish 2 2 1 5 Northern puffer 2 3 5 Radiated shanny 1 2 2 5 Yellowtail flounder 1 4 5 Atlantic cod 1 2 3 Red hake 1 2 3 , Silver hake 1 1 1 3 Northern searobin 2 2 hStripedkillfish 1 1 2 Tcutog i 1 2 American eel 1 1 Black sea bass 1 1 Clupeldae i 1 Hogchoker 1 1 1 1 Little skate Pearlside 1 1 Rock gunnel I I Sand lance sp. I 1 4 Smallmouth flounder 1 1 Squaliformes (embryonic) 1 1
=1 Summer flounder 1 TOTALS 4 28 29 11 20 67 70 255 15 47 330 143 1,019 Collection Time (hrs.) 39 35 46 38 66 69 106 85 66 76 114 66 806 Collection Rate 0.10 0.80 0.63 0.29 0.30 0.97 0.66 3.00 0.23 0.62 2.89 2.17 1.26' '#!hr.)
Table 2. Species, Number, Total Length (mm), Weight (gms) and. Percentage For All Fishes Collected From Pilgrim Station Impingement Sampling, January-December 1986 Length Mean Height Mean Percent of Species Number Range Length Range Height Total Fish Atlantic herring 346 47-258 90 1-114 5 33.9 Rainbow smelt 278 80-220 119 2-55 10 27.3 Atlantic menhaden 113 55-332 90 2-370 13 11.1 Winter flounder 76 53-325 94 1-300 17 7.5 Atlantic silverside 44 86-135 107 3-12 6 4.3 Grubby 30 50-185 88 1-35 10 2.9 Cunner 26 68-155 112 5-66 27 2.6 Alewife 25 68-130 88 1-17 5 2.5 Atlantic toscod 16 58-205 137 2-74 24 1.2 Windowpane 9 45-170 86 1-50 10 0.9 i Bay anchovy 5 68-83 73 3-5 4 0.5 Blueback herring 5 85-120 100 4-14 8 0.5 Lumpfish 5 25-53 39 1-6 4 0.5 Northern puffer 5 40-65 49 2-15 6 0.5 Radiated shanny 5 80-140 116 4-29 18 0.5 Yellowtail flounder 5 50-79 70 2-4 2 0.5 Atlantic cod 3 60-490 '302 4-1,151 473 0.3 Red hake 3 123-237 190 21-110 74 0.3 Silver hake 3 112-146 129 8-18 13 0.3 Northern searobin 2 *0-57 54 2-3 2 0.2 Striped killiftsh 2 65-75 70 3-5 4 0.2 Tautog 2 46-60 53 3-4 4 0.2 American eel 1 - - - - 0.1 Black sea bass 1 100 100 14 14 0.1 Clupeldae 1 - - - - 0.1 Hogchoker 1 125 125 37 37 0.1 1 Little skate 1 452 452 560 560 0.1 Peariside 1 46 46 1 1 0.1
- Rock gunnel 1 - - - -
0.1 Sand lance sp. I 150 150 10 10 0.1 Smallmouth flounder 1 62 62 2 2 0.1 Squaliformes (embry.) 1 67 67 2 2 0.1 Summer flounder 1 290 290 204 204 0.1 i l l
i l Table 3. Annual Impingement Collections (1977-1986) For the 10 Most Abundant Fishes From Pilgrim Station IntaPe Screens During January - December 1986 Number of Impinged Fishes Collected From January - December Species 1977* 1978 1979 1980 1981 1982 1983 1984** 1985 1986 Totals i
. Atlantic herring 24 12 13 8 2 9 2 0 2 346 418 Rainbow smelt 273 3,019 87 95 13 60 57 5 8 278 3,895 Atlantic menhaden 58 51 7 20 0 15 33 2 76 113 375 Winter flounder 64 34 34 15 15 27 20 5 39 76 329 Atlantic silverside 473 722 1,173 14 5,466 133 97 22 174 44 8,318 Grubby 104 51 14 9 24 13 38 15 36 30 334 Cunner 154 61 22 116 55 63 16 6 27 26 546 Alewife 15 131 28 8 11 25 8 12 37 25 300 I
Atlantic tomcod 157 31 30 4 5 14 17 12 18 16 304 g Windowpane 29 4 46 7 8 9 11 8 7 9 138 8 Totals 1,351 4,116 1,454 296 5,599 368 299 87 424 963 14,957 Collection Time (hrs) 1,515.0 1,442.0 494.25 603.75 574.5 687.0 763 1,042 465 806 12,060.5 1 Collection Rate (#/hr) 0.89 2.85 2.94 0.49 9.75 0.54 0.39 0.08 0.91 1.19 1.24 f *No collections were made in September 1977. ! **No CHS pumps were in operation 29 March - August 1984. 4
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. Rainbow smelt was most represented in November impingement collections and are generally dominant ~1n the fall months. .This species has been collected in large numbers, particularly in 1978, and is in 'the top five fishes impinged,
-historically.
I ! Atlantic menhaden dominated the impingement catch in .0ctober (24 specimens) j and were prevalent in November and December _ samples. Historically, menhaden impingement at Pilgrim Station has been trregular although in 1985 they were second in numbers impinged. Most of this species impact concern has been directed at the thermal effluent. Winter flounder occurred predominantly in December, possibly reflecting this
- species offshore Wintering movement. It has been one of the more abundantly j impinged fish over the years, primarily in the February / March period when its l inshore spawning migration is underway.
l ( l Atlantic silverside were greatest in February and March. They are charac-teristically impinged in largest numbers during the early Spring period and ? usually dominate other fishes in numbers collected annually at Pilgrim Station. Monthly intake water temperatures, and impingement rates for the j five dominant species in 1986 are illustrated in Figure 3.
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There were two impingement incidents (20 fish or greater /hr.) at Pilgrim 4 Station in 1986, when one circulating water pump was in operation. The two l j incidents involved 171 Atlantic herring on August 4 and 95 rainbow smelt on i j November 24. All large fish Impingment mortalities have occurred while both 1 l circulating water pumps were operating. l ) 4 6' i l ! l l _ _ _ _ _ . _ _ . . , _ . . _ . . . _ _ _ - . _ . . . _ _ _ . _ _ _ _ _ _ , . _ _ _ _ . . . , . _ . . _ . _ _ _ _ - . _ _ _ _ , . . _ - . _ . _ . . . _ _ _ . -
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