BECO-91-035, NPDES Marine Ecology Studies Re Operation of Pilgrim Station,Semiannual Rept 37,1990
| ML20073K458 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 12/31/1990 |
| From: | Richard Anderson, Wagner E BOSTON EDISON CO. |
| To: | MASSACHUSETTS, COMMONWEALTH OF |
| References | |
| BECO-91-035, BECO-91-35, NUDOCS 9105100135 | |
| Download: ML20073K458 (402) | |
Text
{{#Wiki_filter:___ + W BOSTON EDISON 26 Braintree Hdi othee Park Braintree, Massachusetts 02184 (fpD,*" BiCo9-53 Nuclear Engoeonng Mass. Division of Water Pollution Control Regulatory Branch - 7th Floor One Hinter Street. Boston, MA 02108 NPDES PERMIT MARINE EC010GY MONITORING REPORT
Dear Sirs:
In accordance with Part I, Paragraph A.7 b & c, and Attachment 1, Paragraph 1.F, of the Pilgrim Nuclear Power Station NPDES Permit No. MA0003557 (Federal)
-and No. 359 (State), Semi-Annual Marine Ecology Report No. 37 is submitted.
This. covers the period from January.through December 1990. 7 A
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Semi-Annual Marine Ecology Report h, 37 RDA/ rec /5649 cc: Mass. Division of Hater Pollution Control
. Southeastern Regional Office P.O. Box 537 North Pembroke, MA 02358 9105100135 901231 PDR ADOCK 05000293 R PDR j (cooll [p[< /g I
t BOSTON E0ISON 25 Bram' 9e Hdi Othce Pati, Braintree, Massachusetts o2164 April 26, 1991 E. J. Wagne, vceanoeni BECo 91- 035 Nuclear Engoeerng NPDES Program Operations Section (HCP) Environmental Protection Agency P.O. Box 8127 Boston, MA 02114 NPDES PERMIT MARJ1iLEf0 LOGY MONITORING REPORT
Dear Sirs:
In accordance with Part I, Paragraph A.7.b & c, and Attachment 1. Paragraph I.F, of the Pilgrim Nuclear Power Station NPDES P6rmit No, MA0003557 (federal) and No. 359 (State), Semi-Annual Marine Ecology Report No. 37 is submitted. This covers t'*e period from January through December 1990. v C N t. n w _ E. ). Waa r u)
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Semi-Annual Marine n @ gy Report No. 37 RDA/ rec /5649 i 1
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I I MARINEEC0LOGYSTUDIES. l RELATED100PERATIONOfPILGRIMSTATION I I SEH14UR REPORT E 37 g REPORTPERIOD: JANUARY 1990THROUGHDECEMBER1990 DATEOfISSUE: april 30,1991 )I LI l Compiled and Reviewed by: / M LI ;; :" M"n;;"eries sioiogist g u I l LI lI I """' 'files *Ie'n/Js*fe'e""'"' 2ss!!'?"eNii"E77?'"# Park eraintree, Massachusetts 02184 I
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I-TABLE OF CONVENTS SECTION I
SUMMARY
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II INTRODUCTION III MARINE BIOTA STUDIES IIIA Marine Fisheries Monitoring IIIA.1 Annual Report on Monitoring to Assess Impact of the Pilgrim Nuclear Power Station on the Marine Fisheries Resources of Hestern Cape Cod Bay, January - December 1990 (Characteriza-I 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 I Hestern Cape Cod Ba y, January - December 1990 (Impact on Indicator Species) (Mass. Dept. of Fisheries, Wildlife and Environmental Law Enforcement; Division of Marine Fisheries) IIIB Benthic Monitoring and Impact IIIB.1 Benthic Algal and Faunal Monitoring at the Pilgrim Nuclear 3 Power Station, January - December 1990 (Characterization of 5 Benthic Communities) - (Science Applications International Corp.) III.B.2 Benthic Algal and Faunal Monitoring at the Pilgrim Nuclear Power Station, January - December 1990 (Impact on Benthic Communities) - (Science Applications International Corp.) IIIC Entrainment Monitoring and Impact IIIC.1 Ichthyoplankton Entrainment Monitoring at Pilgrim Nuclear I. Power Station, January - December 1990 (Results) - (Marine Research, Inc.) I IIIC.2 Ichthyoplankton Entrainment Monitoring at Pilgrim Nuclear Power Station, January - December 1990 (Impact Perspective)
- (Marine Research, Inc.)
IIID Impingement Monitoring and Impact I Impingement of Organisms at Pilgrim Nuclear Power Station:
- December 1990. (Boston Edison Company)
January I I n I
I SUMBRY liighlights of the Environmental Surveillance and Monitoring Program re-suits obtained over this reporting period (January - Decembe 1990) ai e presented below. (Note: PNPS was operating at normal power level from l January - December 1990 with the exception of outages during most of March, April and September.) I tintlne_Eliherles MonItoting:
- 1. In the June-August 1990 shorefront sportfish survey at Pil-grim Station, 1,331 angler visits accounted for 568 fishes caught. Bluefish (55%) and striped bass (26%) dominated the sportfish :atch. The presence of a strong thermal discharge component during 1990 resulted in a good sportfishery success I rate compared with outage and low power years covering the shorefront angling season.
- 2. Pelagic fish mean CPUE (Catch Per Unit Effort) for 1990 at the gill net station _ (68.8 fishes / set) de-ilned 19% from 1989 to the lowest level recorded since ?Q77. Pollock (30%) and Atlantic herring (17%) were 47% of the total catch. Both Atlantic herring and pollock decreased substantially from 1989. A significant positive correlation was found for cunner l_ catch (third highest in 1990) and seasonal, Pilgrim Station l
l operational output (thermal loading to the environment). I I I I-1 L - - . .
I
- 3. Shrimp trawl catch for 1990 recorded 22 benthic fish species with winter flounder (41%), little skate (19%) and windowpane (18%) composing 78% of the total. Mean CPUE fcr all species was 2.6 (lowest) at the Harren Cove station, 6.7 (highest) at the intale surveillance station and 3.9 (7.3 in 1989) for all stations pooled in 1990. The presence of substantially larger numbers of winter flounder caught in the intahe embayment, compared to the other stations each year, suggests its attraction as a desirable area for this species.
- 4. Adult lobster mean monthly catch rate per pot haul, in Hay -
I October 1990, was 0.44 lobsters which is similar to the 1989 rate (0.45). The surveillance area (thermal plume) catch rate was 0.32 while the- reference area (control) was 0.27. A negative correlation, approaching significance, was noted between legal lobster catch rate for thermal plume areas, and mean seasonal (May - December) Pilgrim Station output for the period from 1973 - 1983, but not when 1985 and 1990 data were included. The legal lobster catch rate for preoperational/ outage years has not been significantly lower in the thermal plume area than in control areas. The lobster research study, which commenced in 1986, found significantly lower sublegal catch rates at stations closest to the discharge canal and a near significant negative relationship between Pilgrim operation and sublegal ratch in 190n. syi I I-2 g
n a 5. In May - October 1990 fish observational dive surveys, - 6 species were observed in the thermal plume area. Cunner ~ (53%), striped bass (191) and tautog (161) were the most numerous fishes seen, the latter two species being most abunoant in the direct path of tne Pilgrim discharge current. Total number of fishes observed was the second highest of the study and much higher than in 1989. Most fishes were in greatest concentrations at stations in the discharge zone (60%), fol! owed by the control zone (35%) and the stunted zone (5%). These results were different than 1984/1987/1988 (outage years with reduced discharge current), when most fish were observed relatively evenly divided between discharge and am control zones, and similar to 1985/1986/1989 (higher discharge g current years) when fish seemed to greatly favor being in the oath of the effluent.
- 6. Atlantic silverside accounted for 881 of the 1990 haul seine 1
(shore zone) fish catch with a total of 31 species collected. The PHPS ),,take showed higher species diversity compared to exposed coastal stations. Fish captured in the PHPS intake embayment were dominated by Atlantic silverside , sand lance spp. and blueback herring, and included winter flounder among the more numerous specist.. A deeper seine net (10' compared to 6'), to more effectively sample the intake, was utilized beginning in 1984 and resuitn haw e nnally imiloimi thi-area is more similar in fish lanna attraction to an o n i.ua r y than exposed coastal areas. 1-3
.ImphgemenLlionLtor10s: I
- 1. The mean January - December 1990 impingement collection rate was 1.70 fish /hr. The rate ranged from 0.08 fish /hr (July) to 7.16 fish /hr (November) with Atlantic silverside comprising 29.3% of the catch, followed by Atlantic menhaden 22.1%,
butterfish 10.8% and alewife 8.4%. Fish impingement rates in 1985, 1986, 1989, and 1990 were several times higher than in 1984, 1987 and 1988 when Pilgrim Station outages had both circulating water pumps off for various periods of time. 2, in November and December 1990, Atlantic silverside impingement I accounted for 70% of this species annual collection. They have been one of the most abundant species impinged on an annual basis at Pilgrim Station, predominating in 8 of the last 10 years. .
- 3. A small, fish impingement incident was noted on November 19 when a rate of 35 fish /hr. was recorded during continuous sampling.
- 4. The mean January - December 1990 invertebrate c >llection rate I
was 1.lC+/hr with ctenophores dominating, and common starfish and sevenspine bay shrimp accounting for 46.3% and 17.8% of the enumerated catch, respectively. Fif ty-five American lobsters were sampled. The invertobrata impinoemont intet in Inns, 1986, 1989 and 1990 were similar to those recor derl at pilgrim Station during the 1987 and 1988 outage years, despi te lower circulating water pump availability in the outage years. I l-4 g
I 5. Impinged fish, initial survival at the end of the Pilgrim Sta-tion intake slutteway was approximately 10% during static screen
- washes and 27% during continuous washes. None of the dominant
~
species showed greater than 50% survival, overall. I Ehh.. Syne 1LLexe: Fish overflights in 1990 spotted four of five major sprcies categories: herring, Atlantic menhaden, Atlantic macherr I and baltfish. Seven sightings of fish in the nearfield Pilgrim On both October 7
~
vicinity were made, all Atlantic herring. and 31 over 400,000 pounds of this species were observed within
. a few miles of Pilgrim Station. None of these occurrences were reported to regulatory authorities as they were not within 1/2 mile of the discharge canal.
I S.enthic Monitorina:
- l. No new taxa of invertebrates were added to the list of biota for PNPS benthic surveys as a result of analysis of the 1990 samples. A total of 116 species were recorded (37%
polychaetes, 34% mollusks, 22% crustaceans). l
- 2. No notable difference in species richness existed between the Effluent and Reference stat tons based on results of 1990, 1989
-I and ' fall 1988 sampling. The reference stations, which have characteristically ranted a boa <t of thn rffinont -tatinn- in species numbers, appeared more similai to the rilscharae area in late 1988, 1989 and 1990 indicating a lact of response to PHP5 thermal effinnt effects.
I-5
I 3, Review of overall faunal community structure, via cluster an-l alysis, showed that the Effluent Station had a low degree of = similarity compared with the reference stations in f all 1990, but higher in the spring, in contrast, faunal clusterings and aigal community overlap /blomass values showed a general recovery of benthic community structure at the Effluent site compared with reference sites during the three year outage ended in early 1989. _
- 4. The warm-water species, GtKLlarJa .t1LnALae, decreased in the area of the Effluent station during 1986, was completely absent l
in 1987 and 1988, and reappeared in the fall of 1989 and in 1990 during PHPS operation, It was also rare in 1984, before it normally colonized in 1985, indicating a direct relationship to the -lack of therraal effluent in 1984, 1986, 1987 and 1988. 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 outage years (1984, 1987, 1988) and the spring of 1989 transect survey,
- 5. Four observations of the near-shore _ acute impact zones were I
performed during this reporting period. Denuded and stunted
-zone boundaries were . indistinguishable during September 1987 -
June 1989 discharge surveys as a result of the PHPS shutdown. I I I I-6 g
These surveys noted delineated, denuded impact areas in fall 1989 and all of 1990, primarily because two circulating weter i pumps were consistently in operation resulting in maximum , discharge current flow. The area of PNPS-induced scouring impacts in both June and September 1990 was the greatest It had 2 been since 1983; 1835 m and 1,600 m2
, respectively.
E01rAlnment rionitoring:
- 1. A total of 42 species of fish eggs and/or larvae were found in the January - December 1990 entrainment collections (19-eggs, 38-larvae).
- 2. Seasonal egg collections for 1990 were dominated by fourbeard rochling and American plalce (winter - early spring); Atlantic mackerel and labrids (late ;pring - early summer); windowpane and labrids (late summer - autumn).
- 3. Seasonal larval collections for 1990 were dominated by sand lance and sculpin (winter - early spring); cunner and fourbeard rockling (late spring - early summer); cunner and fourbeard rockling (late summer - autumn).
I
- 4. Two lobster larvae were collected in the entrainment samples for 1990, the first recorded since 1982.
I-7
- 5. In 1990 an estimated 3.104 x 109 fish eggs and 3.534 x 108 fish iarvae were entrained at Pilgrim Station, assuming I full flow capacity of all seawater pumps. On an annual basis, eggs were dominated by Atlantic mackerel and the labrid - LimannAa group, and larvae by cunner and sand lance sp.
I
- 6. Total numbers of fish larvae collected for similar volumes of water sampled, in spring and summer 1984 and 1987, were noteably lower than for the same periods in 1983, 1985, 1986, 1988, 1989 and 1990. These results were shown to be related to the f act that both Pilgrim Station circulating water puinps were offline during most of the spring /sununer period 1984/1987, but at least one circulating water pump was operating during the majority of tnis period in the other years.
I
- 7. On no occasions in 1990 were " unusually abundant" -
Ichthyoplankton densities recorded in samples, as defined by the entrainment contingency plan. I I I I I I-8 g
1 I I INTRODUCTION A. Scope and Objective This is the thirty-seventh semi-annual report on the status and results of the Environmental Surveillance and Monitoring Program related to the opera-tion of Pilgrim Nuclear Power Station (PNPS). The monitoring programs dis-cussed in this report relate spcifically to the Cape Cod Gay ecosystem with par _ticular emphasis on the Rocky Point area. This is the twenty-fifth semi-annual report in accordance with the environmental monitoring and re-porting requirements of the PNPS Unit 1 NPDES Permit from the U.S. Environ-mental Protection Aaency (#MA0003557) and Massachusetts Division of Water Pollution Control (#359). A multi-year (1969-1977) report incorporating marine fisheries, benthic, plankton /entrainment and impingement studies was-submitted to the NRC in July 1978, as required by the PNPS Appendix B, Tech. Specs. Programs in these areas have been continued cnder the PNPS U NPDES permit. Amendment #67 (1983) to the PNPS Tech. . Specs, deleted Appendix B non-radlological water quality requirements as the NRC felt they are covered in the NPDES Permit. I The objectives of the Environmental Surveillance and Monitoring Program are to determine whether the operation of PNPS results in measurable effects on the marine ecology and to evaluate the significance of any observed ef-fects. If an effect of significance is detected, Boston Edison Company has committed to take steps to correct or mitigate any adverse situation. I ! I u-, I
1 I These studies are guided by the Pilgrim Administrative-Technical Committee (PATC) which was chaired by a member of the Mass, Division o' Ster Pollu-tion Control in 1990, and whose membership includes representatives from the University of Massachusetts, the Mass. Division of Water Pollution Con-trol, the Mass. Division of Marine Fisheries, the National Marine Fisheries Service (NOAA), the Mass. Office of Coastal Zone Management, the U.S En-g vironmental Protection Agency and Boston Edison Company. Copies of the Minutes of the Pilgrim Station Administrative Technical Committee meetings held during this reporting period are included in Section V. I B. Marine Biota Studies
- 1. Marine Fisheries Monitoring 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 I sites outside the area of temperature increase are being monitored. Pelagic species were sampled using gill net (1 station) collections (Figure 1) made at monthly intervals. In 1981, shrimp trawling and haul seining were initiated which provide more PNPS impact-related sampilng of benthic fish and shore Zone fish, respectively. Shrimp trawling was done once/ month (January - March) and twice/ month (April
- December) at 4 stations (Figure 2) and haul seining twice/ month during June - November at 4 stations (Figure 1).
11-2 I I
I Monitoring is conducted for local lobster stock catch statistics in areas in the proximity of Pilgrim Station (Figure 4). Catch statistics are collected approximately biweekly throughout the fishing season (May-November). I A finfish obtervational dive program was initiated in June 1978. SCUBA gear is utili.ted on biweekly dives from May-October (weekly mid-August to mid-September) at 6 stations (Figure 2) in the PNPS thermal plume area. I In 1986, an experimental, lobster pot trawl monitoring effort was in!tiated to eliminace any biases associated with the collection of lobster stock catch statistics for determining PNPS effects. Ten S-pot lobster trawls were fished in the thermal plume and control areas around PNPS during 1990 (Figure 3). Results of the marine fisheries monitoring during the reporting period are presented in Section IIIA.1 and IIIA.2.
-I
- 2. Benthic Monitoring The benthic monitoring described in this report was conducted by Scientific Appilcations International Corporation, Woods Hole, Massachusetts.
L I I II-3
I The' benthic flora and fauna were sampled at three locations at deptns g of 10 feet (MLW) (Figure 1). Quantitative (rock substratum) sattfle s were coller.ted, and the dominant flora and fauna in each plot were re-corded. Sampling was conducted two times per year (March and Septem-ber) to determine blotic changes, if a y. Transect sampling off the discharge canal to determine the extent of I the denuded and stunted zones is conducted four times a year (March, June, September and December). l
. I Results of the benthic surveys and impact analysis during this period are discussed in Section 1I18.1 and IIIB.2.
- 3. Plankton Monitorino I
I Marine Research, Inc. (MRI) of Falmouth, Massachusetts, has been moni-toring entrainment in Pilgrim Station cooling water of fish eggs and larvae, and lobster larvae (from 1973-1975 phytoplankton and zoo-plankton were also studied). Figure 5 shows the entrainment contingen-l cy sampling station locations to be sampled should the number of eggs / larvae entrained greatly exceed recorded historical averages.- Informa-tion generated through this monitoring has been utilized to make perio-dic modifications in the sampling program to more efficiently address the question of the effects of er.trainment. These modifications have been developed by the contractor, and reviewed and approved by the PATC on the basis of the program results. Plankton monitoring in 1990 emphasized consideration of ichthyoplankton entrainment, Results of I the ichthyoplankton entrainment monitoring and irrpac t analysis for this reporting period are discussed in Section IIIC.1 and IIIC.2. II-4
I
- 4. Impinoement Monitorino I
The Pilgrim Station impingement monitoring and survival program spectates, 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 I being reported on by Boston Edison Company. I A new screen wash slutteway 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. Division of Water Pollution Control as a part of NPDES Permit
#MA0003557. Special fish survival studies conducted from 1980-1983 to determine its effectiveness in protecting marine life were terminated in 1984, and a final report on them appears _ in Marine Ecology Semi-Annual Report #23.
Results of impingement monitoring and survival program, as well as impact analysis, for this reporting period are discussed in Section l- IIID. C. Fish Surveillance Studies I March - November, weekly fish spotting overflights were conducted as part of a continuing effort to monitor the times when large concentrations of fish might be expected in the Pilgrim vicinity. I l II-5 'I
I An annual summary report for this effort for 1990 is presented in Section g IVA, D. . Station Operation History I The daily average, reactor thermal power levels from January through _ December, 1985-1990 are shown in Figure 6. As can be seen, PNPS was in a operating stage during most of this reporting period. E, 1991 Environmental Programs A planning schedule bar chart for 1991 environmental monitoring programs related to the operation of Pilgrim Station, showing task activities and milestones from December 1990 - June 1992, is included as Figure 7. I I I I I II-6 - I I I I
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I I ANNUAL REPORT ON MONITORING TO ASSESS IMPACT I PII4 RIM NUCLEAR POWER STATION OF ON MARINE FISHERIES RESOURCEF OF WESTERN CAPE COD BAY (CHARACTERIZATION OF THE FISHERIES RESOURCr:S) Project Report No. 50 (January to December, 1990) (Volume 1 of 2) I I By Robert P. Lawton, Brian C. Kelly, Vincent J. Malkoski, Mando Borgatti, Joseph F. Battaglia, and David Pichetto I I I l April 4, 1991 Massachusetts Department of Fisheries, Wildlife, and Environmental Law Enforcement I Division of Marine Fisheries 100 Cambridge Street Boston, Massachusetts 02202 I I
I TABLE OF CONTENTS I Section hun I. EXECUTIVE
SUMMARY
1 II. INTRODUCTION 2 III. METHODS AND !GTERIALS 3 IV. RESULTS AND DISCUSSION 14 A. Hydrography 14
- 1. Water Temperature 14
- 2. Salinity 15 B. Fisheries - Lobster 16
- 1. Commercial Lobster Pot-Catch Fishery 16
- 2. Research Lobutor Trap Finhory 17 C. Fisheries - Finfish 22
- 1. Nearnhore Groundfish 24
- 2. Pelagic and Benthi-Polagic Fishon 28
- 3. Shorczone Fishes 32
- 4. Underwater Finfish Observations 35
- 5. Sportfishing Survey 39
- 5. Cunner Roscarch 41 V. HIGl!LIGl!TS 47 VI. ACKNOWLEDGEMENTS 51 VII. LIE RATURE CITED 52 I
I 11 I
I LIST OF TABLES I Table Engc I 1. Seasonal mean surface water temperatures in (*) Contigrade recorded while sampling biota at various locations in the Pilgrim area during 1990. 14
- 2. Checklist of finfish species (following classification 22 of Robins et al. 1980) collected or observed in the adjacent marine waters off Pilgrim Station, 1990.
- 3. Expanded catch and porcont composition of groundfish 24 captured by bottom trawling at four stations in the vicinity of Pilgrim Station, January to December, 1990.
- 4. Bottom trawl catch data for dominant groundfish caught 26 in the vicinity of Pilgrim Station, January to December, I 1990.
S. Catch in number and percent composition of the top 10 29 I fish species sampled by gill not ( 'l panels of 3.0-15.2 cm mesh) in the immediato vicinity of Pilgrim Station, January to December, 1990.
- 6. Shore-zono fishes captured by haul scino at four stations 32 in the vicinity of Pilgrim liuclear Power Station, Juno to 14ovember, 1990.
- 7. Abundance and distribution of finfish species recorded 35 during underwater observations, May to October, 1990.
I I I I I lii I
l I LIST OF FIGURES Ficuie fagn
- 1. Location of Marino Fisheries sampling areas for trawl, 4 gill not, haul scino, lobotor, dive, and sportfish surveys in the Pilgrim study area.
- 2. Lobster pot sampling grid for the commercial lobsterman 4 monitored in +he Pilgrim Power Plant area (surveillanco (ll - 1 1 , li- 1 2 , i .1, and I-12) and reference (E-13, E-14, and F-13) quedrats are shaded) and distribution of his traps samp!cd in 1990.
- 3. Location of experimental lobster gear (fivo-pot trawls) 6 E for Marint, Fishories studios in the vicinity of Pilgrim B Station.
4 Location of bottom trawl stations for Marino Fisheries 6 studies off Pilgrim Station.
, Location of diving stations for the Marino Fisherion 9 observational study off Pilgrim Station.
- 6. Location of gill not sampling for tiarino Fisheries 9 l studies off Pilgrim Station. W
- 7. Location of beach seine sampling in the environs of 12 E Pilgrim Station for Marine Fisheries studies. g
- 8. Creel data forin used at Pilgrim Shorofront to record 12 sportfishing information.
- 9. Monthly commercial lobster catch per trap-haul in the 16 Pilgrim area, 1990.
- 10. Size distribution of lobster captured in the research 19 trap study off Pilgrim Station in 1990.
- 11. Size distribution of lobster captured in the research 21 trap study off Pilgrim Station from 1986 to 1990.
- 12. Mean annual catch por tow by station for pooled 25 species trawled in the environs of Pilgrim Nuclear Power Station, 1982-1990.
- 13. Mean annual catch por tow by station for winter flounder 26 trawled in the vicinity of Pilgrim Station, 1982-1990.
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- 14. Mean annual catch por tow by station for little skate 27 I trawled in the vicinity of Pilgrim Station, 1982-1990.
- 15. Mean annual catch por tow by station for windowpano 28 trawled in the vic nity of Pilgrim Station, 1982-1990.
- 16. Indicos of relativo abundanco (CPUE) for pooled 29 I finfish species captured near Pilgrim Station based on 5 panels of 3.8 - 8.9 cm mosh, 1971-1990.
- 17. Tndices of relativo abundance (CPUE) for pollock 30 captured near Pilgrim Station based on 5 panels of 3,8 - 8.9 cm mosh, 1971-1990.
I 18. Indicos of relativo abundanco (CPUE) for Atlantic horring captured near Pilgrim Station based on 5 panels of 3.8 - 8.9 cm mosh, 1971-1990. 30
- 19. Indicos of relative abundan00 (CPUE) for cunner 31 captured near Pilgrim Station based on 5 panels of 3.8 - 8.9 cm mesh, 1971-1990.
- 20. Indices of relativo abundance (CPUE) for tautog 31 captured near Pilgrim Station based on 5 panels of 3.8 - 8.9 cm mosh, 1971-1990.
- 21. Avorago catch por seino set of shore zono fish 33 (pooled specios) in the vicinity of Pilgrim Station I 22.
from 1984 to 1990. Total number of specios caught por station during 34 seining in the vicinity of Pilgrim Station, 1984-1990.
- 23. Indicos of relativo abundance (fish por divo) for all 36 species observed by divers at Pilgrim Station, 1981-1990.
- 24. Indicos of relativo abundance (fish per di' ) for cunner 37 observed by divers at Pilgrin Station, 1981-1990.
- 25. Indicos of relative abundanco (fish por divo) for tautog 38 observed by divers at Pilgrim Station, 1981-1990,
- 26. Floy plastic anchor tag and tagging gun used to tag 44 cunner off Pilgrim Station. Location of tag on a I tagged cunner is also shown.
I I " I
I. EXECUTIVE
SUMMARY
A modified version of marine fisheries monitoring for Pilgrim 11uclear Power Station, initiated in 1981, was conducted by the Massachusetts Division of Marine Fisheries in 1990. The occurrence, distribution, and relative abundanco of finfish and lobster were monitored according to standardized sampling schemes to identify trends and relationships in the sampling data collected from the study area over time. We focused our efforts on commercially and recreationally important fisheries resources. 11earshore bottom trawling, haul seining, experimental gill not sampling, monitoring of local commercial lobster catch statistics, experimental lobster trapping, observational diving, and a sportfishing crool survey rounded out investigations, catch rates in the Pilgrim area declined from 1989 to 1990 for the top three groundfish (winter flounder, little skato, and windowpane) trawled. The gill not catch of pollock, Atlantic herring, and cunn<>r decreased from last year. Seine catch rates of Atlantic siWorside and juvenile Atlantic menhadon decreased substantially from last year. Conversely, number of fish sighted during the diving study increased considerably, due to record numbers of tautog, striped bass, and bluefish and the resurgence of young-of-the-year cunner. Angling offort at the Shorefront doubled, with sportfish catches tripling last year's catch. Experimental cunner tagging revealed the anchor tag to be suitable for use in future study off Pilgrim Station. Total lobster catch rates in both the experimental and commercial studios increased this year; legal lobster catch rates remained the same, but sublegal rates increased. I 1
I II. Introducti2D A marine monitoring program was conducted in 1990 by the Massachusetts Division of Marine Fisheries (DMF) in an ongoing effort to assess impact on the ecosystem caused by the operation of Pilgrim Nuclear Power Station (PNPS), under Purchase Order No. 67252 to Boston Edison Company (Deco). Our sampling design includes the use of various gear types and sampling strategies that allow characterization of the lobster and numerous finfish populations present in the study area. the proper pairing of an With each piece of gear, impacted station or stations with l comparable reference stations is a primo consideration when sampling. When possible, we have endeavored to have more than one control station. Data collected at reference sites are needed to address natural rates of change in populations. Data on the occurrence, distribution, and relative abundance of lobster and various finfish species were collected following a standardized sampling regime. Measurements, counts, percentages, and indices are used in the analyses. Volume 1 focuses on characterizing the fisheries' resources in the Pilgrim area as a whole. Only essential findings are presented; however, detailed data presentations including statistical tests and supportive data are available upon request. Our intent is to condense the subject matter but still maintain clarity of data reporting and interpretation in a rehdable and integrated format. I I' I I
l III. Methods and Materials commercial Lobster Catch Many commercial and recreational lobstermen harvest the American lobster in the environs of Pilgrim Nuclear Power Station. There are numerous landing sites for their catch along the western shore of Cape Cod Bay, so it is not feasible to monitor directly the entire local lobster fishery. Instead, we opted to sample the trap-catch of a cooperating commercial lobsterman in the Pilgrim study area (Figure 1) and to use his catch records as an index of harvest. Twice a month from May to November, we sampled the entire day's catch of this lobsterman. To facilitate the data collection process and subsequent analyses, the study area was partitioned into a grid (0.8 km2 quadrats) on a nautical chart (Figure 2), and trap-catch was associated with quadrats locatea by LORAN C bearings and/or visual sightings in the field. Data were pooled later for the reference and impact areas. Our analysis included data from 1983 to 1990, because prior to 1983 we sampled the catches of another lobsterman who differed intrinsically in fishing power and gear design. Research lobster Tran Fishina In 1990, we completed the fifth year of a field research lobster study, which was implementad to assess more accurately the impact of the thermal discharge c arrent from Pilgrim Station on the local lobster population. This study allows us to control sampling offort in time and space and, in general, to standardize sampling I ' I
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.I presence of eggs, shell hardness, and disease, and then released in the area of capture. A small cub-samplo periodically was retained I "
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r. s < il / ll \ .. Il .... 1 <a 4r i i ,!g Itg g\ g g i , li l l M .., 4P li ) ' x [!li } i I 'I ['W f)/ c' , j ( !! !I E f l l d I I . E' I I , q: . i ')h s.s/ . , I .'. ; r $ 8' It .s flf I - I g ,p- .\ 1;: I I n. R+._ I't ii ; y r!!. - j %" I, Y'./'g(s 11 - ai 1l / Y 1' }# .x} p I 2 ll l I e l made with a Socchi disk. ) Gill Net Samnling Polagic and bonthi-pelagic fish in the Pilgrim area voro i sampled by fishing a gill not parallel to shore at a depth of three meters (MLW), near a lodge extending north from the mouth of the dischargo canal (Figure 6). The sampling site is partially within the discharge impact arcs. Sampling was conducted monthly throughout the year. To standardizo sots on a yearly basis, the not was set before suncet and retrieved at sunriso the following day to take advantage of the greator sampling officiency of this passive gear during the dark. We employed a sinking monofilament gill not (213.4 m long by 3.0 m deep), which was anchored and buoyed on station, fishing the entire water column at low tido. To counter the bias of gear selectivity, an experimental not was fabricated, consisting of a single " gang" of sovon 30.5 m panels of the following stretch mesh sizes 38 mm, 50 mm, 63 mm, 75 mm, 88 m, 114 mm, and 152 mm. To further reduce sampling bias, the end of the not positioned closest to the discharge canal was reversed on alternato sets. Water temperatures were taken when the not was set and hauled. Our objectivos were to provido systematic collections of finfish for radiological analysis and to obtain timo series records of relative abundanco for dominant species, liaul Soining To monitor finfish occurring in shallow water, i.e., the intertidal zone and the shallow part of the subtidal zone, haul 1 10 I_ I seining was conducted. We sampled biwockly during the daytime at four stations from June to November, when many fishes inhabit the shoreline (Figure 7). Winter /early spring sampling was omitted because cold temperatures reduce or occlude fish distribution in the shoals. Fishes found along the shore include forage species and the juveniles of many important commercial and sport species in the size range most susceptible to power plant impingement. Wo employed a standardized, quantitative beach seining technique, modified after Conover and Ross (1982). The not used at Stations S-2, S-4, and S-5 was a 45.7 by 1.8 m haul seine with a 1.8 m3 bag of 0.48 cm square mesh (twine #63). Because sampling was constrained by the greater depth at the surveillance site (Station S-3, Intake), a dooper soino (45.7 by 3.0 m ) set from a small powered skiff was used there. Duplicato hauls woro made at each station. All citos were sampled within i 2 hours of low tido. Surface water temperature and salinity were measured at each statiori. For each station, we endeavored to keep the area (m ) seined 2 constant to maintain a consistent effort within a site over time. Captured fish were identified and enumerated. Up to 50 individuals of each species captured were measured. Unusually large catches were subsampled to reduce mortality, and total catch was g B extrapolated from volume-unit counto. Catch per unit effort (defined as catch per seine haul) was calculated for dominant species. Seine data have been collected since 1981. I 11 I I I I 1, 1 I _ 1 .i {E , a g l, K:b ! [ I gg } 3 II #f ! 1 1 j .]; :
- ]r j I ij di ?
Il 1 , n 3 I, j,i b ' l !, 5;' i 8 a I !! I ,t 1 }! l j' l - 1 I 8 . E 11 - I ai l i i , 1 ,. i { , - E I I I I ~ - l'*i ,di t . i t IkQ ,/ ~ j i J} # i 3., ,,. ... . . iir.. ; v : I 9 4.. q,. 1.. } .v .. lr.4 L. u _ c j ~. 4!I ! 9.?- e cf 3 }i 2 3 l . . ~- ':/ - 1 IL = I n g I I Sportfish Survey The sportfish catch at Pilgrim Station's Shoref ront recreation area was monitored from June through August by PNPS public l relations' personnel at the watertront, in a cooperative offort with us to maintain a database on recreational fishing in the Pilgrim area. A questionnaire was used to record daily catch data (Figure 8) . We also spot-checked the area for recreatiorial fishing during April, May, and September to November. I I I I I I I I I I g u I i i I ; IV. RESULTS A11D DISCUSS 1014 A. HYDROGRAPHY
- 1. Water tomoerature In the marine waters of the inshore sector of western Cape Cod Bay, ambient surface temperatures have boon recorded as low an -l'c in winter and as high as 23' C in mid-summez (Lawton et al. 1983).
Bottom temperatures have ranged f rom -l' '. (winter) to 21' C (lato summer) . Warming begins in late March or April (Table 1), and a thermocline gonorally forms by early summer, lasting into the fall. Surface to bottom temperaturo differentials (highest at the surface) have boon as great as 4.8' C. Water temperatures during spring consistently have warmed f astor and boon higher at the mouth of the nearby estuary of Plymouth, Kingston, Duxbury Bay off Long I Point (Table 1) . With the exception of springtime, temperaturos were highest in the Dischargo area in 1990 off Pilgrim Station, where waste heat olevated ambient temperatures. Table 1. Seasonal mean surf ace water teaseratures in (*) Centigrade recorded while sanpling blota at verlous locations in the Pitoria area daring 1990. itf15 LMet ton Winter spring Sunver fall B (Jan. Mer.) ( Apr. Jure) (July Sept.) (Oct. Dec.) Long Point
- 16.3 18.3 10.5 Warren Cove / Rocky Point 3.7 13.6 18.0 9.9 Discharge 4.9 13.6 19.7 13.3 Intake 2.8 11.9 19.0 10.9 White Horse Beach /Manomet Point 2.8 12,9 18.0 10.1 Grand Mean 3.6 13.6 18.6 10.9 su
*ho tenperatures recorded tecause no sanpling 16 done at this site during winter. over the last eight years (1983-1990), water temperatures I overall were high in 1983 and 1985. Most noteworthy was the Il I L markedly lower temperature regime during most of 1984. There was a perceptibly cooler spring in 1984, and lower spring water temperatures translated into lower commercial lobster catches in the Pilgrim kroa for 1984 (Lawton et al.1990) . Lower temperatures most likely reduced molting, which may have slowed recruitment to legal size. Ambient seasonal mean surface temperatures in 1990 were very similar to those in 1989.
- 2. Salinity Salinities in the study area were relatively high, ranging from 28% to 33b. There is a minimum of fresh water influence in our study area. The lowest salinities were recorded at Long Point, at the mouth of the nearby estuary. Tidal exchange is sufficient in Capo Cod Bay so that its waters vary little in salinity f rom the contiguous waters of Massachusetts Bay.
I i 15 l l l I B. EL'iHERIES - LOBSTER
- 1. fammercial lobster not-catch fishery Monitoring the commercial American lobster (Homams americama) j fishcry in 1990 in the Pilgrim study area began in May and f
concluded in October. Lobster catch statistics and biological data (i.e., carapace length - CL, sex, shc11 hardness) were collected . i' over the six months during 12 sampling trips aboard a commercial lobster boat. Data woro recorded on 5,423 lobster taken from 2,145 lobster pot-hauls. Overall catch por pot for lobster (comprised of legal - CL 2 1 82.6 mm - and sublegal lobster) from the Pilgrim area was 2.5, as compared to last year's value of 2.2. Eightoon porcent (952) of the total catch were legal-sized lobster for an annual legal catch rate of 0.44 lobster per trap-haul, which is identical to tast year's value. Relatively low - 3w u monthly legal catch rates occurred from May through July (0.24-0.26) , ' followed by high rates (0.78-0.76) , j in August and September (Figure ,,, p ,_ ;. _ 7 .- _ ; _ 7 il MM JUN JUL 44 6f.P 001 9). The monthly catch rate of lmioxuwtn taawe m ounaws l g both sublegal and legal lobster 3 Figure 9. Monthly ccmireretet tobster catch para 11oled P P'h*"I '" 'h' PiL8" " ' 0' that of the tota 1 pooled lobster catch rate. The annual ratio of sublogal to legal I lobster was 4.7:1. Femalos comprised 52% of the annual catch. Monthly sex ratios were consistently in favor of females at 1.1:1. There were 50 16 s ~E ovigorous (ogg-carrying) females sampled (1.8% of the female catch), of which 25 (0.9% of all females and 50% of all ovigorous females) were sublagal. The overall percentage of ovigorous females was again higher in late summer through early fall (September 2.4% and October 6.8%) than in summer (1.0% in Juno and 0.0% in July). This reflects the two-year reproductivo cycle of the American lobster (Aiken and Waddy 1982), where females generally mate after the summer molt, but do not extrudo fortilized eggs until fall of the following year. The eggs are then carried externally throughout the winter and hatch from late spring through summer.
- 2. Research Lobster Tran Fishina We trapped lobster from June through September 1990 in the environs of pilgrim Station. This year was the fifth of our research trap fishing. We completed 54 sampling trips. Effort consisted of 2,625 trap-hauls, while sample size was 9,734 lobster of which 10.9% woro legal-sized. In 1990, the minimum legal size for lobster in Massachusetts remained at 2 82.55 mm (3.25 inches)
CL, the first year in the past three without a gauge increase. The past changes in the minimum legal size were not accompanied by an l increase in the size of the trap escapo vent. This resulted in incroaced catches of sublegals as reflected in the annual catch ratio of sublegal to legal lobster which was 5.8:1 in 1988, 6.6:1 in 1989, and 8.1:1 in 1990. The number of lobster of all sizes captured ranged from 0 to 15 por trap-haul, with legal catch ranging from 0 to 4 and 17 I sublegal, O to 15. In 7% of the pot-hauls, no lobster were taken. The overall mean catch per trap-haul (CTH) in the study crea of lobster (pooled for rall sizes and of both sexes combined) has increased steadily over the five years, ranging from 1.2 in 1986 to 3.7 in 1990. Monthly catch rates (legal and sublegal) in the study area in 1990 generally increased from June tnrough August, then declined in September. The beginning of the molt occurred in June as indicated by relatively low catches then, followed by a marked increase in catch per pot and total catch in subsequent months. Males again outnumbered females in the research trap catches, comprising 54% of the total. Conversely, females have outnumbered males in past commercial catches made in the slightly deeper waters of western Cape Cod Bay (Kelly et al. 1987; Lawton et al. 1989). Again this year, the commercial catch data slightly favored females (52%). A prepondelance of males in shoal water pot-catches was reported by Briggs and Muschacke (1979) in Long Island Sound. There were 53 egg-bearing (ovigerous) females sampled which represented 1.2% of the female catch; the percent of females ovigerous was 0.7% in last year's research catch. Over the years, this value has often hovered near 1% in commercial catches from western Cape Cod Bay (1.8% in 1990) but has been as high as 14% in Buzzards Bay (Collings et al. 1983). The mean cize of female lobster at maturity is considerably smaller in the warmer waters south of Cape Cod, such as Buzzards Bay (Aiken and Waddy 1980; Van Engel 1980). I 2* I. 1 I. I culls (lobster with missing and/or regenerating claw (s)) captured during research fishing in 1990 represented 29% of the catch, an increase from 27% in 1989 and 23% in 1988. In general, the cull rate in commercial catches has increased in the Pilgrim area during the decade of the '80's, concomitant with a rise in the commercial and recreational lobstering effort. The commercial lobster traps employed in this study contain rectangular escape vents (4 4. 5 x 152. 4 mm). They retain legal-sized lobster; however, sublegals are captured to an extent. The size range of lobster sampled the summer of 1990 was 30 to 124 mm CL. The overall no in size was 76.1 mm, which is only 0.1 mm greater than the ave;: age in 1989. Sublegals averaged 74.7 mm CL, and legals, 87.2 mm CL. Size-catch distributions ,, ,,,,,,,,,, , were plotted for 1990 data q io- f 1 (Figure 10) and for all five ,, years, 1986-1990, together .- t j (Figure 11). These length- '~ hff Ikhe,. I frequency histograms display the oMM imnununw w mmukMTM combined effects of lobster " " " d'n ,0 3 teno7ng7 ,3 I avail-.sility, vulnerability, and Figure 10. size distribution of tobster exploitation. The general captured in the research trap study off Pilgrim stepwise increase in catch from 50 to 75 mm CL suggests that at the latter sizes, lobster are increasingly vulnerable to retention in the traps. The mode was again at the pre-recruit size of 81 mm. Reduced catches of lobster below 75 mm are probably the result of I 1 l I I l gear design (vent escapement). The lower numbers of lobster at l legal size and greater reflect high fishing mortality via j exploitation from the intensive commercial and recreational lobster fisheries of the Pilgrim area. From 1988 to 1990, markedly more larger lobster (2 80 mm CL) were sampled (Figure 11) than in 1986 and 1987. Enhanced recruitment of sublegals into the pre-recruit and 1cgal size range l was most likely the reason, since the Cape Cod Bay lobster resource ' is over-exploited (Estrella and Cadrin 1989). Estrella and Cadrin (1989) reported that the mean catch rate of marketable lobster in Massachusetts coastal waters was 11% higher than in 1987, while the total state commercial landings increased 8%. Cape Cod Day i commercial landings were up again in 1989, while the mean 1990 commercial legal catch rate for the Bay remained relatively strong. Ennis (1993) found that with lobster exploitation rates as high as 94% in the Comfort Cove area of Notre Dame Bay, Newfoundland, recruitment is the main factor influencing the abundance of legal-sized lobster in a given year. I I I I I I I: MMMm l l PERCENT FREQUENCY /1 c / 14 ' g fi = i: ~ I di 10- p} Eg S 8- g[ yj Ik 6- , 4 il 4- Sf N %=gd:r}i cI f ~"""*'*"*'" f 'M2cD5xd&denx;r' ctv b 5 {f g 2- ~ MeechaabbbMay , _ ' _ j ? 30Gd/w/224zzidgopppix/ ed l b_, _ i , s . , ,, _ ,2, ,,,, _ , ,, s , , g ,, _ ld 0 i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i mrr i i i i i i i i i i , i i i i i i i i i 50 55 60 65 70 75 80 85 90 95 100 105 CARAPACE LENGTH (mm) 1 I l1986 55555I 1 9 8 7 E 1988 I fl989 R@#31990 l I f Figure 11. Size distribution of lobster captured in the rcsearch j trap study off Pilgrim Station from 1986 to 1990. C. FISilERIES - FINFISil A species check list of fish observed or collected by all gear types in the Pilgrim area in 1990, complete with scientific names (Robins et al. 1980), is found in Table 2. Table 2. Checklist of finfish species (following classification of Robins et al. 1980) collected or observed in the adjacent marine waters off Pilgrim Station, 1990. Class: Chcedrichthyes Orders Squaliformes Family: Carcharinidae requiem sharks 3 Mustetus cents (W tchill) = smooth dogfish Family: Squalidae dagfish sharks Squalus acenthies Linnaeus - spiny dogfish Orders Rajlf orces Family: Rajldae skates P,313erinoce)Mitchilt-Littleskate Class: Osteichthyes Order: Clupelformes up Family: Clupeldae
- herrings M pq11 eestival13 (MitchlLL) blueback herring h psewoherenaus (Wilson)
A atewtfe Erevoortia tyrannus (Latrobe)
- Atlantic menhaden Ctures berenws berenous Linnaeus Atlantic herring Family: Engrautidae anchovies Anehon mitchitti (Valenciennes) bay anchovy Orders Salsontformes Family: Osmeridae smelts 91m.erus !!s*1t5 (Mitchill) rainbow smelt order Cadiformes Family: Gadidae codfishes ga.jul mochua Linnaeus Atlantic cod Microondus tomeed (Walbaun) Atlantic temcod Pollachius virens (Linnaeus) pollock Urophycis tenuis (Mitchitt) white hake Uroobycis M (Walbaun) - red hake Family: Zoarcidae eetpouts Macrotoarees emericanus (Schneider) ocean pout Order Casterostelformes Family: Gasterosteldae sticklebacks Gesterosteus eeuteatus Linnaeus threespine stickleback Acet tes cruadeceus (Mitchill) - foutspine stickleback Family: Syngnathidae pipefishes and seahorses Synonethus fuscus Storer northern pipefish Orcer: Atheriniformes Family: Atherinidae - silversides Menidia menidie (Linnaeus) Atlantic silverside 22 1
E' .s I I Family: Cyprinodontidae killiffshes FuMuWg fnnlelis (Walbam) striped kittifish f undulus beteroetitus (Linnaeus) ournichog I Order: Perciformes family: Percichthyldae
- ternperate basses Morone sexatills (Walbaan) stripd bass I Family: Serranidae see asses centroorfs ug strfate (Linnaeus) black sea bass Family: Pomatomidae bluefishes Pomatonus settatrix (Linnaeus) bluefish Family: Carangidae Jacks Seriote renate (Mitchill) banded ru&ierfish Decaoterus inacerettus (Cuvier) mackeret scad Familys Seisentdae druns
&ticirrhus sonettlis (Bloch and Schneider) - northern kingfish family: Scorteldae a meckerels and tur.as Egile sterbevs Linnaeus Atlantic mackeret family: Sparidae - porgies Stenotomus chrysops (Linnaeus) scup family: Labridae = wrasses Toutone 2".d111 (Linnaeus) tautog Tautooot at>rus adtoersus (Waibaus) cmner I. Family: Hugilidae mullets M curema Valenciennes white suttet Family: Pholidae gunnels P,121it nunnettus (Linnaeus) rock gunnel Family: Stromateldae butterfishes Pepellus irteeenthus (Peck) butterfish Family: Triglidae
- searobins
.3 Prionotus carolinus (Linnaeus) northern searobin PrionotM1 tydens (Linnaeus) striped searobin I family: Cottidae sculpins Hemitrioterus ameriennus (Gmelin) sea raven Myoxocettelus senaeus (Mitchilt) grubby Myoxocercatus octeoceemselnosus (Mitchill) - Longhorn sculpin HvonocecAatus scorpius (Linnaeus) shorthorn sculpin Family: Cyclopteridae turpfishes and snellfishes Cvetooterus Itrws Linnaeus tmpfIsh Family: Anunodytidae a sand lances Alvsxfvtes 3m Order: Pleuronectiformes Family: Bothidae lefteye flounders -I Peratichthys oblonaus (Mitchill) - fourspot flounder Sconhthatmus aquosus (Mitchlll) windowpane Family: Pleuronectidae righteye floundsrs I M ferruainea (Storer) yellowtait flounder Pseudocteuronectes americanus (Walbaum) winter flounder Order: Tetracdontiformes ! g Family: Tetraodontidae puffers l Seteeroides maculatus (Bloch and Schneider) - northern puffer I I 23 l I
- 1. Nearshore Groundfish During 133 bottom trawls in the study area in 1990, we collected a total of 514 fish, representing 22 species (Table 3).
Three species - winter flounder, little skate, and windowpane - comprised 79% of the total. Overall catch per tow (a measure of catch per unit effort, or CPUE) calculated from pooled species and station data was 3.9, a 47% decline from 1989 (Figure 12). Table 3. Experded catch' and percent corrposition of groundfish captured by bottom trawling at four stations in the vicinity of Pilgrim Station, January to Decenter,1990. Station 1 3 4 6 Warren Pilgrim Priscilla Pilgrim Percent of Species Cove Discharge Beach Intake totals total catch Winter flounder 35.0 !.0.1 36.2 -98.4 209.7 40.8 Little skete 8.0 15.4~ . 39.3 37.1 99.9 19.4 Windowpane 30.0 16.1- 24.6 24.6 95.2 18.5 Ocean post 6.0 6.0 : 3.0 7.0 22.0 4.3 Yellowtait flounder 0.0 8.2' 5.5 1.0 14.5 2.8 Atlantic cod 1.0 0.t, 8.0 . 5.0 - 14.0 2.7 Longhorn sculpin 1.0 6.0 . 1.0 3.4 11.4 2.2 Worthern pipefish 6.0 1.5 1.0 2.2 10.7 2.1 Atlantic silverside 0.0 5.1. 1.0 3.2 9.4 1.8 Curvwe 0.0 2.5 0.0 4.8 7.3 1.4 other species' 3.0 5.1 3.0 9.1 20.2 3.9 total fish 90.0 106.0 122.4 195.7 514.1 Wunter of tows 35 34 1 35 29 133 Catch per tow 2.6 . 3.1 3.5 6.7 3.9 Percent of catch 17.5 20.6 23.8 38.1 Wunter of species 10 12 - 11 16 22 ' Catch rates were expanded for tows less than the standard 15 minute duration. ' Represents pooled totals f rca 12 s.pecies of low catch abundance. Shaded colums are data collected at surveillance stations. This is the lowest rate recorded for the entire study and a continuation of the marked downward trend recorded in our trawl catches since 1987. Such low numbers of fish make detection of impact from the operation of Pilgrim Station very difficult and confound efforts to separate impact from natural variation. However, review of stock assessment work by the National Marine I 1 l Fisheries Service (NMFS) g,, n g , ,3,, ,,g , 2 i ................... l Northeast Fisheries Center (NEFC 3 1989) suggests that our findings x- " l ' b, ' . ) l reflect the generally depressed "il.. j ; state of groundfish abundance in , ,, 3 [{hgy[g I the Northwest Atlantic. Indeed, 1962 1983 t@64 19e5 twe6 1987 m swmi a swee " AR %#.8 10 % M40 he swm 4 their 1989 status report states a swm e uns m swio4 that the abundance of groundfish Figure 12. Mean annual catch per tow tv station for pooled species trawled in the eiwirons of and flounder "...are at Pilgrim kuclear Power Station, 1982 1990, historically low levels.", the result of increased fishing mortality throughout the region. In light of this assessment and the fact that Pilgrim Station was in outage from 1986 to 1988, it is unlikely that depressed local abundance resulted from an impact of plant operation. Catch rate also was calculated for individual stations, the l highest being found in the Intake (Station 6) where CPUE (pooled species) was 6.7. The Intake has yielded the highest station catch rate since we began trawling there in 1984. Priscilla Beach (Station 4) and the Discharge (Station 3) followed with 3.5 and 3.1, respectively, while catch rate was lowest in Warren Cove (Station 1) at 2.6 fish per tow. liinter flounder Ranked first in total catch (41% - all stations pooled), winter flounder also was numerically dominant at each station except Station 4. However, overall CPUE declined for the fourth consecutive year to a new low of 1.6 winter flounder per tow I 25 I (Figure 13). Similarly, , , , , , , , , , 80 . .. . . . . m. m. analysis of coast wide es . : assessment data by the Northeast
- ss a ,
Fisheries Center (NEFC) reveals io . l that overall winter flounder h j abundance in the Gulf of Maine vm has declined substantially in U8 *"*" ' UU "* * *""' CD swioN 8 E TOfAL recent years (NEFC 1989). The Figure 13. Mean annual catch per tow by station for winter flomder trawled in the vicinity of Intake ranked first in winter Pilgrim station. 1982 1990. flounder catch with an annual mean CPUE of 3.4 (Table 4), a decrease of 33% from last year. Annual mean CPUE at the Discharge site (Station 3) dropped from 3.1 (1989) to 1.2. Warren Cove and Priscilla Beach had the same low winter flounder catch index (1.0 I fish per tow). Table 4. Bottom trawl catch data' for dominant groundfish caught in the vicinity of Pilgrim Station, January to Deceeer.1990. Winter Little Station flourder skate Windowpane Mean catch per tow 1.0 0.2 0.9 Mean size (cm) 31 39 25 Site range (cm) 9 43 30 48 17-34 3- 5 Mean cate.h per tow 1.2 0.5 0.5 Hean size-(cm) 31 36 25 size range (en) 10 39- 21 49 14 31 4 Mean catch per tow 1.0 1.1 0.7 Mean size (cm) 28 37 26 $lte range (cm) 9 39 18 51 17 30 .y
- Mean catch per tow ' 3.4 1,3 0.8 Neen alle (cm) ' 29.- 40 23 E g
81 e range (cm) . . 9 43 . 25 51' 12 28 ' Catch rates were expanded for tows less than the standard 15 minute duration. Shaded rows are data collected at Survelltance stations. I E lI l Comparison of the annual mean size of winter flounder captured at each station (Table 4) revealed little variation between stations in 1990. This differs from previous years when winter flounder trawled in the Intake embayment tended to be smaller (annual mean size) than flounder caught at the other stations. Little skate Little skate comptised 19% of the overall catch. Mean annual I catch per tow for all stations pooled was 0.8 (Figure 14) , down 50% from a 1989 value of 1.6. As wuwoca or rias esa row "j g . . . . . . . . . . . with winter flounder, overall is - - t}- I to - . , catch rate of little skate was . ., p-the lowest we have recorded for . q j this study. Comparison with 8 } } , ,pgj 1962 1W 1004 486 1000 1987 4 00 llMe 1990 Gulf of Maine catch rates was YEAR not possible as the NEFC data U * * ** ' C * * ** * ****"' O swiose EE Tom did not differentiate between Figure 14. Heen annual catch por tow by station for little skete trasted in the vicinity of catches of little skate and Pilgrim Stetton, 1982 1990. Winter skate (Raja occl/ata) . The highest annual station catch rate gl.3 little skate per tow) was recorded in the Intake Embayment (Table 4), closely followed by Priscilla Beach (1.1). Warren Cove and the Discharge had the lowest CPUE values, 0.2 and 0.5, respectively. Comparing data over the years (Figure 14) reveals regular fluctuations in relative abundance at all stations. Windownano Windowpane ranked third in overall trawl catch (18.5% - pooled data). Mean annual CPUE for all stations combined was 0.7, r %ilar I l I to a value of 0.5 windowpane per o m ng ,,g , * ... . ..., .a. m tow in 1989 (Figure 15). s. E e - g I. Following a sharp decline in d L y ' abundance has 1988, relative j } g T remained fairly stable, albeit , . } 4 ggg i . , , ,... , .. - - E at a depressed level. A very YEAR E $ [^,[ ' *** thin-bodied species, windowpane $ '[
- are not commercially exploited. Figure 15. Mean annual catch per tow by station for windowpane trewted in the vicinity of na As such, they are not a target Pilgrim Station, 1982 1990.
species for stock assessment; no NEFC data was available for this species. Among the four stations, annual CPUE for windowpano was fairly consistent, ranging from 0.5 to 0.9 fish per tow. Other Species Comprising 21% of the total catch, the remaining 19 species were not captured in abundance. Overall catch rate for this group (pooled species and stations) was 0.8 fish per tow and no distributional patterns were discerned. I
- 2. Pelaaic and benthi-Delacic fishes Monthly gill not catches in 1990 yielded 26 finfish species numbering 885 fish. The top 10 species are listed in Table 5. No set was made in February because of inclement weather.
The annual mean catch rate (catch per standard set) for pooled species by gill net (5 panels of 3.8 - 8.9 cm mesh) declined to an all-time low of 68.8 fish per set (Figure 16). Catches of pollock and Atlantic herring, the two dominant species in gill not catches 28 == I Table 5. Catch in nunber and percent cwposition of the top 10 fish species sanpled by 91ll net (7 penets of 3.815.2 cm mesh in the twediate vicinity of Pilgrim Station, January Decenter,1990. Percent of species Nwber Total Catch j I 1. 2. 3. 4. PotLock Atlantic herring 1autog Striped bass 267 152 105 87 30.2 17.2 11.9 9.8
- 5. Atlantic sackerel 50 5.6 i 6. Cunner 47 5.3
- 7. Alewife 38 4.3
- 8. Bluefish 28 3.2
- 9. Atlantic mertaden 18 2.0
- 10. Smooth dogfish 16 1.8 Total 26 species 808 91.3 I over the years, decreased in 1990 and contributed to the lower
.overall catch rate. Pollock ranked first at 30% -rm mut ert om ; of the catch, and I- Atlantic ***' Yj - herring second at 17%. Cunner ,co , }4 @,h j j I 7 2 9 1 1 - ,. % (5.3% of the catch) fell from isoa 2 A $' ? $ %$ - E T 4 ! h fh;! f-its traditional third position 'm' -Sh $ $ 4 h I? ! h 3j g ! $ s r7 f3
- , ? % i [ e z g E 1 ] ? $ 1 ?
i s $ {j ! .A S s s g - to sixth in the hierarchy of $ f f , I gill not catch and was replaced by tautog at 12% of the catch. vivsvavevsve nvowso etwoo e4weevseww YEAR Figure 16_. Indices of retetive ab m dance I The first three (CPUE) for pooled finfish species captured near species' had PILgets station based on 5 penets of 3.8 8.9 cm mesh, 1971 1990, consistently dominated gill net catches since 1971, with few exceptions. Pollock The catch rate for pollock decreased again in 1990 and was at a depressed level not seen since 1975 (Figure 17). The'long-term time series of relative abundance reveals a wide range in catch .I. 1 I I rates from a low of about 20 m, ,m um,, ,n pollock per gill net set to a io . - - '" ' ~ high of about 140. - ; '00 - Atlantic herrina ]j l ~ so - , ; ~ oo j ," i ' " ~ The catch rate for Atlantic 3 s s ? ;; ]7j3 q > herring markedly declined from a : i " I j ' .,, [; j j$ '; j2 (;14c j; ,;; s1 ,,1 + 5 i r ;1 1 , 11 1989 to 1990. Overall, the "" "" " "" "" " *" "" "" *" catches of herring have Figure 17. Indices of relative atmiance (CPUE) for pollock captureo near Pilgrim Stetton based fluctuated as greatly as any fish species sampled by the various gear typee, This species was at its lowest point in abundance in the Pilgrim area in 1985 but reached a zenith in 1988 (Figure 18). punner The relative abundance of ,,,, , _ ym,, ,y too cunner in the Pilgrim area has y " I been markedly down since 1985, with this year's catch rate ioo - ' 3 jj being the lowest of the 20-year ,, . ? 7 s ~ " time series (Figure 19). The ' , ra _ e 1 4 4!B)filra m fd adult population size appears to "" "" "" "" "" ** m ,' "'* "" "" "" be depressed at present in the Figure 18. Indices of relative abundance (CPUE) for Atlantic herring captured near Pilgrim station based on 5 penets of 3.8 8.9 cm mesh, 1971-Pilgrim area.- However, numbers 1990, of small cunner (13-38 rm) were observed by project divers this year in the control area. In almost 20 years of research trawl data from Mount Hope' Bay, we find that the relative abundance of cunner there has been markedly down since 1985 (Marine Research, Il I_ u Inc. 1990). This parallel in winue s*wn eacw ran ut stock abundance decrease from so - two widely separated - 1, so - geographical areas is most _ do - " interesting and may indicate - l, [] ro ', - I that cunner abundance is Lea..aub s oh4 . - .:a 3 influenced by cycles that may be yg region-wide. Figure 19. Irdices of relative studanc.e (CPUE) f or cunner captured near Pilgrim Stetton based Other Snecies The catch rates for Atlantic menhaden and Atlantic cod decreased slightly from last year, while tautog, striped bass, Atlantic mackerel, and bluefish increased substantially in relative abundance. The second highest gill net catch rate for tautog was obtained this year (Figure 20) . Striped bass, bluefish, and ,, ,,, ,,, n e,, c, , , , 7 , , mackerel have an affinity for ,, - the thermal offluent at Pilgrim 'o '
- l. s -
n ) Station (Lawton et a]. 1987). . - y - Their numbers are generally low . - - y in the Pilgrim area when the ' ' 2 i ,%Em on :L ,1. . m a; power plant "" is not fully """"""'""%'""""""*" yg operational. Pilgrim Station Figure 20. Indices of relative atuence (CPUE) for tautog captured near Pilgrim Stetton based lB increased its annual operational "' P'"*** # 3'8'8 ** * 'h' 70' capacity, and thermal component, from 29% in 1989 to 72% in 1990, and with that, gill not catch rates rose from 0.5 to 2.5 for bluefish, 0.8 to 4.2 for mackerel, and 0.4 to 7.1 for striped bass. 31 ) l I
- 3. Shore-Zone Fishes E A total of 19,881 fish comprising 31 species was sampled by haul seining from June to November, 1990 in the study area (Table 6). Water temperatures and salinities measured at the time of sampling ranged from 4' to 25' c and 25b to 32%, respectively.
Three taxa - Atlantic silverside, sand lance spp., and blueback herring - comprised 95% of the seine catch totals. The mean catch per standard seine haul for all stations and fish species pooled (245.4) decreased 16% from the 1989 catch rate (291.3) but was considerably higher than that for 1988 (168.2). Table 6. Shore tone fishes captured by haul seine at four stations in the vicinity of Pilgrim Nuclear Power Station, June to Novect>er,1990. Stati.00 Warren Pilgrim Manomet Long Percent Catch Species Cove Intake' Point Point Total Total Rate Attentic silverside 7,002 s:989. 3,362 6,155 17,508 88.1 216.2 Sand tance app. 77 '593: 35 10 715 3.6 8.8 Blueback herrirg 18 ?643a 7 2 670 3.4 8.3 other species
- 44 508.. 177 259 988 5.0 12.2 Total 7,141 T 2,733 ; 3581 6,426 19,881 5 Nunter of sets 21 J 19::: . 19 22 81 Catch per set 340.0 7143.8 188.5 292.1 245.5 Number of species 13 23i . 13 18 31 Percent of total catch 35.9 i13.8 L 18.0 32.8 100
'45.7 m x 3.0 m seine; other sites sarnpled with 45.7 m x 1.5 m seine.
- Represents pooled total for 28 species of Lower abundance.
Shaded colum is data f rom surveltlance station. A decrease in the catches of Atlantic silverside and juvenile Atlantic menhaden centributed to the overall decline in the catch rate for the study area in 1990. Conversely, the catch of blueback herring increased from last year. Catch ratos for pooled species decreased at all stations (Figure 21). ' lim seine catch by station was highest overall at Warren Cove, where 36% of the total was obtained (Table 6). This was a direct 11 B I result of the large catch of . , , , , , 1000 Atlantic silversides there. The ,, . n catch rate at Pilgrim's Intake 'a- 1 was lower than last year and the ' I . r lowest since 1984. The low an b Ef a bn I m wu me t ou ma overall catch rate there in 1990 " W munseeove C3 pnaam ortus was partly attributable to ma --n.=, ca u . reduced catches of sand lance, Figure 21. Average catch per seine set of shore tone fish (pooled species) in the vicinity of normally a dominant species in the Intake. Atlantic Silverside Atlantic silverside dominated catches in numbers of fish as it has every year of seining operations, accounting for 88% of the fish taken by haul seine, of the total ellveraide cLtch, 40% was obtained from Warren Cove and only 6% from the Intake. This species generally was absent from fish collections in June, while both juveniles and adults were caught in July. Dominating catch per unit effort (catch per set) in the study area from July through November, the silverside ranked first in percent frequency of I. occurrence in catches. However, the overall catch rate decreased somewhat from 1989. l Sand Lance and Winter Flounder Ranking second in seine catch, sand lance spp. were captured g in greatest numbers (83%) in Pilgrim's Intake embayment. Catches g were highest in June and July. Winter flounder comprised 0.9% of the seine catch. The highest catch rate (6.0 winter flounder per I lE l I seine haul) was again obtained in the Intake. Of the flounder seined, 76% were captured from this location. Seasonality add Diversity Seine catches (all species pooled) were lowest in June and highest in August. Larger catches were associated with higher ambient surface water temperatures. In November, reduced catches were made at all sites. Silversides and winter flounder, in declining numbers, still inhabited shore-zone waters in the fal). In fact, the former species had dominated impingement collections at Pilgrim Station during the proceding winter months (January through March), ,, ,,,,,,, The highect number of so- - so- , - species (23) seined on an annual eo. , p basis was taken in the Intake [. . p [ (Figure 22). As to monthly j h > catches for the study area, the ** um .uan om c:s mm was am u .o m eo.n highest number of species (18) G La* = C= was captured in both September Figure 22. Total numer of species caught per station during seining in the vicinity of Pilgrim and October. Of the 31 species seined overall, only 6 were captured at all 4 stations, while 13 were collected at single sites. Eight of the 13 were seined exclusively in the Intake. Pilgrim Intake and Long Point shared 14 species in common in the catch. Both locations are generally protected from heavy wave action and possess a degree of cover which includes vegetation, thus providing suitable habitat for many small fishes. By way of \ 34 l I s contrast, Warren Cove and Manomet Point have little cover and are l
- subject to the action of heavy surf. Reid (1954), reporting on the
~ importance of vegetation to fish in shoro-zone nursery areas, found the least populated areas were those with substrato devoid of vegetation, whero protection was lacking and food not as abundant. We consistently have sampled a higher number of species in the Intake and at Long Point (Figure 22). The number of fish caught at Warren Cove and Manomet Point surpassed that in the Intake in 1990, primarily because of ths large catches of silverside at these f ormer sites. Briggs and O'Connor (1971) reported that the Atlantic silverside preferred sand bottoms to those with vegetation.
- 4. Underwater Finfish Observations observational diving began in early May, with a total of 14 dives made through mid-October. Over 2,500 fish, comprising 6 species (Table 7), were observed at the sampling stations (Figure 23).
Table 7. Abundance and distribution of finfish species recorded E during underweter observations, May to October, 1990. kunt)er Percent Stetton $pecies observed of where most by divers total abundant Cunner 1,365 53.2 C, Striped bass 481 18.7 D. Teutog 420 16.4 0, Bluefish 294 11.5 0, Other* 3 0.2 Total 6 species 2,563
- Shorthorn sculpin and Winter flouM er 35
I Invertebrates noted ,,,,,,,,, included the blue mussel (Mytihes F, i T ,40- ~ = cdulis) , lobster, starfish (Astcrias . -% : = '~' spp.) , and rock crab (Canceritroratus) . ?~ g We qualitatively observed Irish moss (Chondms crispus) as to its .,..,,.3 . . . , . . . , , , , , , , , . , , , , growth and distribution in the R aia**am. m oma., am. o c.emi a . l Infant BAA REPR8484TS ,0TAL 72N PS A DIVE FOR TM8 S,hpt AA84 discharge area again in 1990. Figure 23. trdices of relative obedence (fish per dive) for all species observed by divers at Estimates of lateral Pilgrim Station, 1961 1990. visibility (obtained with a diver-held secchi disk and metered line) ranged from 2.5 m to 7 m (averaging 4.8 m), depending on sea condition and incident light. The number of fish sighted in 1990 (2,563) was the second highest recorded for the entire study and greatly exceeded the 1989 total of 800 fish. Using number of fish sighted per dive as an index of relative abundance, we plotted data from 1981 to 1990 I (Figure 23). In 1990, project divers observed 183 fish per dive, a substantial increase from 1989 (66 fish per dive) . Contributing to this rise in number of fish observed was a resurgence in the number of cunner sighted, particularly of very small individuals ($ 2 cm), and the record numbers of tautog, striped bass, and bluefish. These findings, with the notable exception of cunner, were corroborated by our gill not data. The 1990 gill not CPUE values for tautog, bass, and bluefish were among the highest recorded for the entire study. As shown in Figure 23, fish were observed more often in the discharge area (60%), Stations D; and D 2 , than in the 36 I control and stunted areas, where 35% and 5% were sighted, i L- respectively, cunner The species seen in greatest numbers by p'roject divers was the i cunner which comprised 53% of the total fish recorded (Table 7). A cunner per dive index of 98 was more than double that noted in cowca rta ur I 1989 (44). A plot of these data _ (Figure 24) for the entire study ~ ~ reveals the 1990 index to be on im h a par with pre-1984 levels, an , O - ~ ' , apparent departure from the , l o -t _ a _ n .i _ u _ w & 1 overall decline in local '**'"2 '" " '"h'n" ' ' ' ' * "
- t abundance we have documented Figure 24. indices of relative atmunee (fish per dive) for cunner observed by divers at since that time. That this was ' '
k not mirrored in our 1990 gill net catches may be explained by examining individual length estimates made during diving observations. Over 70% of the cunner sighted in 1990 ranged in size from 2 to 3 cm. Fish this size are able to freely pass through even our smallest gill not mesh (3.8 cm) and are therefore not subject to capture. Additionally, cun.ar of this size do not venture very far from their home structure. Cunner were found at all stations but were most common in the control area at Station C . 3 Tautoa Ranked third in fish sightings (Table 7), tautog were recorded in the highest numbers of the study; their high numbers in the area 37 1 I were reflected in project gill ,,m y, net catches. A comparison of 3 , the fish per dive index for this ' j species (Figure 25) indicates y M p that local abundance has greatly *E ie . A i$ 5 @ i$ j b increased from the nadir noted ' ] h gg {'; p g g $ in 1987. It should be noted, " " " * **' g *
- y however, that the number of Figure 25. Indices of relative atmsance (fish per dive) for tautog observed by divers at rautog observed in the discharge "*""'
- area has fluctuated widely since the inception of observational diving. Tautog were generally found to be milling about the mouth of the discharge canal, often moving as a group behind or beneath aggregations of striped bass.
Strined Bass and Bluefish Striped bass and bluefish ranked second and fourth, respectively, in 1990 diver observations (Table 7). Indices of 34 fish per dive for striped bass and 21 fish per dive for bluefish are the highest recorded in our study. Seasonal migrants, local occurrence and abundance for both species can be strongly affected by year-class strength and fishing pressure along their migration routes. Striped bass were last observed in abundance by divers in 1985 (148 fish). Fifty-two bass were noted in 1989, none in 1988, and only 11 for 1986 and 1987 combined. Though commonly angled from the area in and around the discharge canal, bluefish never have occupied a position of dominance in diver records, e.g., no bluefish were observed by divers from 1984 to 1988. Both species "18 I_ I were sighted almost exclusively in the discharge area, moving as distinct groups into and out of the mouth of the discharge canal. On several dives in 1990, we observed both bass and bluefish moving in the discharge area at the same time. With very little mixing between species groups, the bass were layered at or near the bottom and the bluefish arrayed from mid-water to just below the surface. I 5. Soortfishina survey The Shorefront area at Pilgrim Station was open to the public during daylight hours from April through November in 1990, providing shore-based salt water sportfishing opportunities for eight months of the year. To assist us, Boston Edison public relations personnel (familiar with sportfishing) conducted an informal survey of the shore-based recreational fishery at the power plant during the period of 19 May through 23 August, which was comprised of 74 sampling days (28 weekend days, 2 holidays, and 44 work days). Prior to and after the survey, DMF biologists made spot checks at the Shorefront to monitor sportfishing activity. A reported 1,300+ angler-trips occurred during the actual survey, with 570 fish caught comprising six species. The daily average number of shore fishermen at the Shorefront was 18. Of the six species landed in the sportfishery, two were pelagic fishes: bluefish and striped bass, and four were groundfish: winter l flounder, cunner, tautog, and Atlantic cod. The monthly catch rate l l l ranged from 0.3 fish per anger-trip in August to 0.6 fish in June, with an overall average of 0.4. se g I I l Angling from the outer intake breakwater occurred primarily on 3 the seaward side and was directed toward groundfish in general. Bottom fishing specifically for winter flounder prevailed in the intake of Pilgrim Station, witn anglers fishing from the sandy beach at the head of this man-made embayment. From the two discharge canal jettios, fishermen primarily sought striped bass and bluefish in or on the edge of the ef fh'.cnt current. Few anglers were observed at the Shorefront throughout April and until mid-May. Activity was again relatively light in November. Fishing effort was greatest in June and July, declining in August. A dedicated group of fishermen angled for bass and bluefish in September and October, but there were fewer bottom fishermen in the fall. Although weekend days and holidays comprised 41% of the days sampled, 59% of the fishing trips occurred at these times. Bluefish (55%), striped bass (26%), winter flounder (11%), and cunner (6%) comprised 98% of the surveyed sportfish catch. Of the monthly totals, striped bass predominated in May at 69% of the catch, bluefish (40%) and striped bass (38%) in June, bluefish (71%) and cunner (12%) in July, and bluefish (87%) again in August. The highest monthly total was garnered in June, when both bluefish and striped bass were abundant in the area of the discharge. The highest catches of bluefish and cunner were obtained in July, while landings of striped bass and winter flounder peaked in June. We made the following observations when no creel data were being collected. On several days in late September, we observed 40 I c' large numbers of bluefish breaking in the thermal plume of Pilgrim Station. The fish were active at the purface for up to four hours. t on one of the days, we recorded bluefiah, some weighing over 4.5 kg, landed by anglers fishing off the discharge jetties and from boats trolling through the thermal plume. On another day, bluefish from 2.7 to 4.1 kg and a striped bass measuring 89 cm and weighing i 7,7 kg were caught frorr of f the discharge jettj es. 1I During an observi.tional dive in the discharge area in late September, we sighted an aggregation of about 05 bluefish swimming in a long oval pattern in the thermal plume from the mouth of the dis,harge canal out to about 80 m (262 ft). An aggregation of about 50 striped bass was also observed in the discharge area. It is very evident that the discharge current from Pilgrim Station improves the quality of fishing in the Plymouth area.
- 6. Cutmer Research Backaround To better quantify our observational diving program, we will commence a research study of tagging cunner during 1991 in the Pilgrim area. We will monitor cunner movements and distribution patterns in relation to the waste-heat discharge current from Pilgrim Station and resultant zone's of impact. This offort should shed light on the mobility and dispersion of this species as related to the impact of the thennal ef fluent.
Cunner inhabit inshore tenporate reefs and are especially abundant in the Massachusetts Eay region including Cape Cod Day. I I I Forming discrete localized populations, cunner exhibit only limited seasonal inshore / offshore movements as controlled by water temperature, occupying small home ranges for extensive periods of time, they are ideal indicator subjects for monitoring short and long-term perturbations in the environment. , Gill net records for 20 years, impingement data, sportfish surveys, and diving observations clearly identify cunner among the dominant members of the groundfish community in the Pilgrim area. The intake at the power plant, a man-made embaym nt formed by the construction of two breakwaters, and the discharge canal jetties provide structure for a temperate-water reef community. Large ' boulders provide substrate for attached macroalgae and sessile fauna that serve as cover and a food source, respectively, for cunner. The boulders and the crevices in associated rocks also provide shelter (home sites) for the cunner, required during their nocturnal sleep phase. Cunner are omnivorous and feed both benthically on the benthos (e.g. , mussels, barnacles) and on suspended food items in the water column while facing into a current (Olla et al. 1975). When the two circulating seawater pumps are operating at Pilgrim Station, adult cunner show evidence of being attracted to the discharge current at least on flood tides, presumably to feed. At low tide, the effluent current probably is too strong and turbulent for cunner, making the path of the discharge untenable under such conditions. The potential sources of Pilgrim Station intake impact, on the n g I_ I negative side for cunner, are entrainment of the their pelagic eggs and larvae, and entrapment and impingement of the juvenile and adult stages. In addition, the circulating water dischargo, laden with waste heat and periodically with chlorine, can affect cunner in the receiving waters. Capture and tagging To capture cunner, we will use weighted, baited minnow traps lI
- constructed of vinyl coated wire with the following dimensions
30.5 cm x 30.5 cm x 58.4 cm with a 1 cm2 opening in the mesh of the wire. The bait will be frozen fish (pollock, bluefish) and/or crushed blue mussels held in a bait bag and suspended inside the trap. I The tag we selected had to be suitable to a relatively small fish (such as cunner) and had to be visible to divers. Floy plastic anchor tags (63.5 mm in length) will be inserted in the dorsal musculature on the left side using a tagging gun (Figure Preliminary tagging operations were conducted in November 1989 at the Woods Hole Oceanographic Institute (WHOI) and again in May 1990' . Our intent in this first phase of our work was to assess tag retention, fish survival, and visibility of different colored tags below the water's surface under somewhat controlled conditions. We tagged and held fish in a holding car placed in a small boat well off the WHOI pier and in an aquarium at the National Marine Fisheries Service facility, also located in Woods Hole. All the cunner held were fed fresh fish or crushed mussels on a regular R I I I I I n 'L_w'.; I f l I. I FLAG I \.i I ~ STEM e ,1 ~ I -ANCHOR I I Figure 2e,Floy plastic anchor tag and tagging gun used to tag cunner off Pilgrim Station. Location of tag on a tagged cunner is also shown. I 44 I E. I basis, and observations were made of their condition and behavior. To test the visibility of varlow s: r Ts, our divers took different color tags to a depth of 1 2 h T'oods Hole Harbor to simulate conditions of less than c;.v s visibility. With a measured visibility of 3 m, the hand-held red and blue tags were easily seen, but the orange, pink, and yellow ones were not as readily seen. I Twelve cunner (10 tagged and 2 controls) were placed in a holding car in May 1990, held for 18 days, and then released under the WHOI pier. All were doing well, although one of the cunner had lost its tag and was scarred in the area of the body where we had
- p. aced the tog. A sportfisherman caught one of the tagged cunner on re 'ceel under the pier in mid-June. During the last week of Junu .e SCUBA diving, we observed four of the tagged cunner under the pier; these fish appeared to be normally responsive in behavior, including their swimming ability.
Eight cunner (six tagged and two controls) of 2 12 cm total length were placed in an aquarium tank and held for 86 days with no
- I loss of tags or known tagging mortality. From this preliminary work, we believe that the Floy anchor tag is suitable for our field study off Pilgrim Station in 1991.
We then proceeded into "hase two of tag evaluation and moved our field work into the study area off Pilgrim Station. Between early August and early October of 1990, cunner were trapped and tagged on five different days; all fish were released in the area of capture. Only cunner 2 12 cm total length (which are probably 'I . I I at least two years of age) were tagged because fish smaller than this were deemed too small to accommodate the tag. Five traps were fished along the seaward side of the outer breakwater at Pilgrim Station, and their locations were noted in diagrams or field data sheets. Soak time ranged from 20 to 90 minutes. For each trap hauled, the number of cunner caught and their measurements were recorded. A notation was made of the ones tagged. After the fish were trapped, they were placed in a coolor I filled with ambient scavator. Those too small to tag were released, while the larger fish were tagged and held for a short while to ascertain their well-being prior to release. By October, 84 cunner had been tagged. On a dive in mid-October along the seaward side of the outer intake breakwater, many cunner were observed and among them were four fish that had been tagged on an earlier date. The tags on three of the fish, however, appeared to have the flag at the top of the tag removed with only the stem remaining, possibly having been bittan off by other fish. We cannot rule out the possibility of differential mortality from predation because of the colored tag. With this phase of the study completed, we will conduct an expanded program of cunner tagging this summer off Pilgrim Station. I l I 46 B I V. HIGHLIGHTS Lobster - commercial Fishery
- 1. Catch statistics and biological data for the commercial lobster fishery in the Pilgrim area woro collected from 5,423 lobster sampled from May through October, 1990.
- 2. Catch per unit ef fort of total lobster (2.5 CTH) increased 14%
from 1989 (2.2 CTH).
- 3. Legal catch rate was unchanged from last year, averaging 0.44 for 1990; the range was from 0.24 in May to 0.78 in August.
Lohster - Research Studv
- 1. Fifty-four sampling days of research pot fishing (June to September, 1990) yielded 9,724 lobster (54% malo; 46% female) captured from 2,625 trap-hauls, with legals comprising 11% of the catch.
. 2. Study area catch ratos of legals (2 82.6 mm carapace length-CL) declinod 9% from 1989, the first annual decline in the five-year time series. Conversely, study area sublogal (< g a 82. 66 mm CL) catch rato increased 10% from 1989, having rison l4 annually since 1986. l 3. Only 1.2% of the research catch of female lobster were ovigorous (carrying eggs).
- 4. Carare.ce longths of lobster in research catches ranged from 30-124 mm, and averaged 76.0 mm, which is the same mean size as last year.
- 5. The cull rato increased from 27% in 1989 to 29%.
I 8 I ligarshore Groundfish
- 1. Twenty-two fish species were collected by bottom trawling in the nearshore area of Pilgrim Station.
- 2. The average catch per standard tow for all specios and stations combined declined to 3.9 fish por tow.
- 3. Wintor flounder ranked first in total catch (41%) and was the numerical dominant at each station except Station 4; total flounuer catch declined from last year.
- 4. Little skate again ranked second in total catch (19%); overall abundanco dropped by 50% to 0.8 fish per tow.
I Polacic and 13cnthi-nelacic_.11ahen
- 1. Comprising 26 species, 880 finfish were gill notted during 11 overnight sets.
- 2. Annual mean CpDE of pooled species (68.8) declined 19% from 1909 to the lowest recorded since 1977.
- 3. Pollock ranked first, comprising 30% of the catch. Atlantic horring was second (17%) and tautog was third (12%). I Shore-zone Fish I
- 1. Thirty-ono fish species were captured in the 46.7 m haul seine study from June through November, 1990.
- 2. Decreases in the catch rates of Atlantic silversido and juvenilo Atlantic menhaden contributed to the decrease of the overall 1990 mean catch por soino haul for all species combined.
48 i_ _ _ _ _ _ . _ ______._m__-- - I
- 3. Catch ratos for pooled species decreased at all four sitos.
- 4. Atlantic silversido continued to dominato catches, comprising 88% of the total catch and ranking first in both overall CPUE and os*rall porcent frequency of occurrence.
- 5. Send lance opp. were second in numorical abundanco (4%) but low in frequoney of occurrence, and were taken primarily at the Intake embayment.
- 6. Juvenilo winter flounder, which comprised only 1% of the total catch, were also obtained primarily in the Intake.
- 7. Total number of fish caught was greatest at Warren Cove, but species diversity was highest in the Intake.
I Underwater Finfish Observations
- 1. A total of 2,563 fish, comprising 6 species voro observed during 14 dives in 1990.
- 2. Total number of fish observed was the second highest of the study and greatly excooded the 1989 totalt 60 % woro sighted in the denuded zone, 35% in the control zone, and 5% 3n the stunted zone.
- 3. Cunner wao the most common species soon (53% of the total) and was found at all stations.
- 4. Fish por dive indicos for tautog, stripod bass, and bluefish were the highest recorded for the dive study.
I I , 49 8 I Sportfishina Survev
- 1. An informal creal survey of sportfishing was again conducted at the P13 grim Shorofront recreational area from late May thro *Agh late August.
- 2. Reportedly,1,331 angler trips were mado by shore fishermon to l
the area and about 568 fish, representing 6 species, woro i caught during the survoy.
- 3. 111uefish (55%), stripod bass (26%), wintor flounder (11%), and '
cunner (6%) comprised 98% of the sportfish catch.
- 4. Effort and catches were up considerably from last year.
I Cunner Research
- 1. Wo assessed tag rotontion/ visibility and tagged fish survival 2.
under controlled conditions for cunnor. The Floy plastic anchor tag appears suitable for our field l study off Pilgrim Station in 1991. I I I I I I 50 a_ I VI. ACKNOWL}'DGEMENTS The authors acknowledge the contributions of Heil Churchill, Stovo Cadrin, and Paul Caruso, staff members of the Division, who assisted in diving operations. We thank Chris Kyranos for allowing us to sample his commercial lobster catch, and Raymond Dand and Robert Ellonborger for collecting creol data at the Pilgrim shorefront. A special thanks to Kim Trotto and Mario callahan of the Division for word-procoscing various sections of this report. Finally, wo appreciate the role of Robert D. Anderson of Boston Edison Company, W. Leigh Bridges of the Division, and the Pilgrim Administrative-Technical Committoo for their input on study programs and editorial comments on project reports. I I I I I I I I I I I VII. LITERATURE CITED Aiken, D.E., and S.L. Waddy. 1980. Maturity and reproduction in the American lobster. Can. Toch. Rep. Fish Aquat. Sci. 932 59-71 Aiken, D.E., and S.L. Waddy. 1982. Coment gland development, ovary maturation, and reproductive cycles in the American lobster, Romams amcdcanus. Journal of crustaccan Biology 2(3): 315-327. Boston Edison Company. 1980. Benthic map overlays and assessment an of benthic monitoring programs, Vol. 2. Nuclear Engineering g Dept., Environmental Sciences Group. Boston Edison Company, Boston, MA, USA. 25 pp. Briggs, P.T., and J.S. O'Connor. 1971. Comparison of shore-zone fishes over naturally vogotated and sand-filled bottoms in Great South Bay. Now York Fish and Game Journal 18 (1)115-41. Briggs, P.T., and F.M. Mushacko. 1979. The American lobster in western Long Island Sound. Now York Fish and Game Journal 26(1) 59-86. Collings, W.S., C. Coopor-Shochu, S.C. Hughes, and J.L. Buckley. 1983. The spatio-temporal distribution of American lobster, l Homams americames, larvac in the Capo Cod Canal and approaches, 5
- p. 35-40. ID M.J. Fogarty (ed.), Distribution and relative abundance of American lobster, Homams americanus, larvaot New g England investigations during 1974-79, 64 pp. NOAA Technical 3 Report, NMFS SSRF-775.
Conover, D.O., and M.R. Ross. 1982. Patterns in seasonal abundance, growth, and biomass of the Atlantic silversido, l Atenidia menidia, in a New England estuary. Estuarios 5(4) l 275-286. Ennis, G.P. 1983. Annual variations in standing stock in a Newfoundland population of lobsters. North American Journal of Fisheries Management 3:26-33. Estrella, B.T., and S.X. Cadrin. 1989. Massachusetts Coastal Commercial lobster trap sampling program May-November, 1988. Commonwealth of Massachusetts, Division of Marine Fisheries. , 23 pp. l I I 52 g a l l Kelly, B.C. , V.J. Malkoski, S.J. Correia, R.P. Lawton, M. Borgatti, and B. Hollister. 1987. Annual report on monitoring to assess impact of the Pilgrim 14uclear Power Station on marine I fisheries resources of western Cape Cod Bay (Vol. 1). Project Report lio. 42. In: Marino Ecology Studios Related to Operation of Pilgrim Station. Semi-Annual Report lio . 29. BECo, Braintree, MA. Lawton, R.P., W.T. Sides, E.A. Koulohoras, R.B. Fairbanks, M. I Borgatti, and W.S. Collings. 1978. Final report on the assessment of possible offects of Pilgrim lluclear Power Station on the marine environment. Project Report 14 0 . 24 (1970-1977). Massachusetts Division or Marine Fisheries. IDI I Marine Ecology Studies Related to operation of Pilgrim Station. Final Report, July 1969-December 1977. Vol. 1, sect. III.9, 19 pp. 11uclear Engincoring Department, Boston Edison Company, 800 Boylston Stroot, Boston, MA 02199. Lawton, R.P., V. Malkoski, S. Correia, B. Kelly, C. Sheehan, M. Borgatti, and P. Brady. 19e7. Final Roport on Marine Recreational Fishing at the '?11 't in Station Shortfront:1973-i 1975, 1983-1986. Filgrin 11uc , car Power Station Marino Environmental Program Report Series lio . 3. Boston Edison Company. 53 pp. Lawton, R.P., B.C. Kelly, V.J. Maikoski, M.R.Borgatti, and J.F. Battaglia. 1990. Annual Report on monitoring to assess impact I of Pilgrim liuclear Power Station on marine fisheries resources of western Capo Cod Bay. Project Report 110. 48 (Jan . -Doc . 1989). ID: Marine Ecology Studios Related to Operation of Pilgrim Station. Semi-Annual Report. 35. Boston Edison I Company, Braintree, MA. I Marino Rosearch, Inc.1990. Brayton Point Investigations: quarterly Progress Report. 103 pp. olla, B.L. , A.J. Bojda, and A.D. Martin.1975. Activity, movements, I and feeding behavior of the cunnor, Tauroplahn4s adsperus, comparison of food habits with young tautog, Tautop onitis, and off Long Island,11ew York. Fish Bull. 73 (4): 895-900. Pottle, R.A., and J.M. Green. 1979. Territorial behavior of the north temperate labrid, Tautoplabnes adspesus. Can. J. Zool. 7 2337-2347. Reid, G.K., Jr. 1954. An ecological study of the Gulf of Mexico I fishes in the vicinity of Cedar Key, Florida. Bull. Mar. Sci. Gulf and Caribbean 4 (1): 1-94. I I I i' Robins, C.R., R.M. Dailey, C.E. Bond, J. R. Brooker, E. A. Lachner, I , R.H. Lea, and W.B. Scott. 1980. A list of Common and g Scientific llamos of Fishes from the United States and Canada. 3 1 4th Edition. Special Publication 11o. 14. American Fisheries Society. 174 pp. Van Engol, W.A. 1980. Maturity and fecundity in the American i lobster, Romams americanus - a review. Can. Toch. Rop. Fish. Aquat. Sci. 932: 51-58.
- I I
I I I I I I I I I I I a_ I I I ANNUAL REPORT ON I MONITORING TO ASSESS IMPACT OF I PILGRIM NUCLEAR POWER STATION ON MARINE TISHERIES RESOURCES OF WESTER'1 CAPE COD BAY (IMPACT ON INDICATOR SPECIES) Project Report No. 50 (January-December, 1990) (Volume 2 of 2) By I Robert P. Lawton, Drian C. Kelly, Vincent J. Malkoski, Mando Borgatti, Joseph F. Battaglia, and David Pichotte I I I - I April 4, 1991 Massachusetts Department of Fisheries, I Wildlife, and Environmental Law Enforcement Division of Marine Fisheries 100 Cambridge Street Boston, Massachusetts 02202 lI lI !I I I TABLE OF CONTENTS Section Eggg I. EXECUTIVE
SUMMARY
1 II. INTRODUCTION 2 III. RESULTS AND DISCUSSION 4 A. Physical (Abiotic) Factors 4
- 1. Power Output and Thermal Capacity 4
- 2. Dischargo Current 5
- 3. Water Temperaturo 7 B. Impact of Pilgrim Station on Fisheries Resources 10
- 1. Cunner 10
- 2. Lobster 19
- 3. Striped Bass and Bluefish 34
- 4. Atlantic Silverside 46
- 5. Atlantic Monhaden 51
- 6. Winter Flounder 56
- 7. Pollock 63 IV. IMPACT PERSPECTIVE 69 V. CONCLUSIONS 70 VI. ACKNOWLEDGEMENTS 80 VII. LITERATURE CITED 81 lI
'I lI 11 I
I LIST OF TABLES Table pano
- 1. Summary of indicator species and rationale for 3
- i. selection to assess impact of Pilgrim Nuclear Power Plant on marine life.
, 2. Catch pnr unit effort from research lobster 27 gear in the Pilgrim area for 1990.
I I I I I I lI ! I l I 'I lI . I I lii I
I LIST OF FIGURES
- 1. Annual means and 18-year cumulativo mean 4 I
Pilgrim Station Unit I Capacity Tactor n (MDC Not %) for 1973-1990. g
- 2. Circulatin scavater pump operation by 6 month at P Igrin Station for 1983-1990.
- 3. Surface water temperatures in the vicinity B of Pilgrim Station averaged by season for the years of high plant operational status (1983, 1985, and 1990) and for the transition year (1989).
- 4. Avorage seasonal standard 5-panel gill not catch for cunner and respective seasonal 15 I MD0 Not % at Pilgrim Station, 1973-1990.
- 5. Annual commercial legal lobster catch por 22 trap-haul in control and impact areas near g Pilgrim Station, 1983-1990. g
- 6. Commercial legal lobster catch rates 23 (catch por trap-haul por set-over-day) for western Cape Cod Bay, 1981-1990.
- 7. Legal lobster catch rates (CTHSOD) by area 27 E from research lobster gear fished in the 3 vicinity of Pilgrim Station, 1986-1990.
- 8. Sublegal lobster catch ratos (CTH) by area 28 from research lobster gear fished in the vicinity of Pilgrim Station, 1986-1990.
- 9. Monthly legal lobster catch rates (CTHSOD) 30 by area from research lobster gear fished in the vicinity of Pilgrim Station, 1990.
- 10. Monthly sublegal lobster catch rates (CTH) 32 by area from research lobster gear fished in the vicinity of Pilgrim Station, 1990.
a g,
- 11. Mean catch per standard haul coino set of 50 Atlantic silversido collected along the Plymouth shorelino, Western Cape Cod Bay, 1984-1990.
iv l I_'
I 1
- 12. Mean annual 5-panel gill not catch of 55 menhaden and annual % MDC operational level at Pilgrim Station for 1973- .
l 1990.
)
- 13. Mean annual catch per tow of winter 62 I flounder and annual % MDC operational level at Pilgrim Station for 1982-1990.
I 14. Mean annual 5-panel gill net catch of pollock and annual % MDC operational level at Pilgrim Station for 1973-67 1990. I I I I I I I LI I I " I L
I LIST OF PIATES Plato 1. Biologist collecting length-frequency data from the catch al of a commercial lobsterman in the proximity of Pilgrim gl Station. Lobsters constitute the area's most valuablo i fishery resource. I Plate 2. Operations aboard a fishing vessel used during the experimental lobster study. This invoutigation is j designed to better assess the impact on lobsters of the 3; thermal effluent at Pilgrim Station. 3I Plate 3. Retrieval of the experimental gill not after a standardized overnight set in the thermal plume area. caught in the not is a smooth dogfish, a common summer migrant in the Pilgrim area. Plate 4. Fishes caught by gill net in the area vf the thermal plume at Pilgrim Station. Gill not catches include commercially important species, e.g., Atlantic cod, 3 pollock, Atlantic mackcrol, stripod bass, and winter g flounder. Plate 5. Bottom trawl being set to sample groundfish in the inshoro waters of western capo cod Bay, catches are used t- measure potential impacts of Pilgrim Station on the benthic fish community. Plate 6. Typical trawl catch is processed which includes identifying, enumerating, and measuring the different a species for environmental assessment. Catches of winter g flounder have been consistently larger at the Pilgrim Station intake trawl station. Plate 7. Haul soining in the intake embayment at Pilgrim Station: l the not 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 3 g potential impact on shoro-zone fishes. Plate 8. Haul seine catch processed on the beach near the Pilgrim Station intake (fish are enumerated and measured) . Among the shore-zone fishes are important forage fish such as the Atlantic silverside and sand lance, and the juvenile E stages of several commercial species such as the winter 5 flounder and Atlantic menhaden. Plato 9. Diclogist-diver deploying a trancoct line between observational stations. Diving observations have recorded the greatest number of fishes in the "donuded" zono directly off the dischargo canal. l vi n.
I Plate 10. A tautog foraging at the mouth of the discharge canal (Station D) at Pilgrim Station. A popular catch of recreational fishermon, tautog are in the Pilgrim area from spring through autumn and have boon used as an
" indicator" organism to assess stress imposed by the rolcase of the heated offluent.
Plate 11. Pictured is the thermal offluent discharging into capo I cod Bay and anglers fishing off the dischargo jotties and from boats in the plume background by the calm water. which is visible in the Stripod bass and bluefish, which are attracted to and concentrate in the thermal I current, are the dominant species sought by sport fishermon at this location. I Plate 12. Anglers sooking sportfish at the mouth of the dischargo canal. Casting artificial lures is the most popular method of fishing the discharge current which attracts a I variety of species. I I I I I I I vik l lI ,,,e
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- 1. rXECUTIVr SUlitiMW In accordance with the Pilgrim Nuclear Power Station HPDES I Permit requirements of the U.S. Environmental Protection Agency and the Massachusettr. Division of Water Pollution Control, marino fisheries monitoring and reporting were conducted in 1990.
Fisheries data were collected from comparablo referenco and surveillance stations to assess power plant impact. We emphasized data comparisons between 1983/1985/1990 (high operational years,
>70% thermal capacity) and the years of low or no output 1984 (outage), 1986 (low output), 1987 and 1988 (outago), and 1989 (low output).
The past year of high operational status at Pilgrim Station underscored the following findings. Sportfish catches and diver observation of bluefish and stripod bass were markedly higher in 1990 along with a strong thermal dischargo current, as both species are attracted to moving water (i.e. currents) to food. Cunner show an attraction to the ef fluent current at the plant dischargo based on gill not sampling and diving observations. There is evidence from our research lobster program of a relationship between sublegal lobster catch rate in the dischargo area and the release of the cooling water discharge. Whilo diving, we have observed few lobster residing in the immediate area of the discharge canal when the plant is operating because the velocity of the current limits their mobility. Winter flounder, the dominant groundfish in the Pilgrim area, continued its decline in abundance as evidenced by the lowest trawl catches of the time series. I I
I II. INTRODUCTION The Massachusetts Division of Marine Fisheries conducts a field monitoring investigative program to assess environmental impact of Pilgrim Nuclear Power Station on marino fisheries resourecs in the offsite waters of western Cape Cod Bay. This investigation was funded by Boston Edison company under Purchase order No. 67252 in 1990. Focusing on the lobster population and finfish populations in the Pilgrim area, wo sampled U surveillance l and comparabic reference sites throughout the year employing a variety of gear types and obtained replicates over time for analytical data analyses. Measurements, counts, percontages, and indices of abundance are used to examine roletionships in the data both spatially and temporally. Data are summarized and displayed in graphs, plots, and tables to elucidato patterns and appraise assumptions in relation to past findings. Descriptive and inferential statistical procedures aro employed to test for station differences or differences over time betwocn operational and non-operational periods. Volume 2 is an assessment of Pilgrim Station impact on selected indicator species in the local marino environment. With this volume, a new approach is being taken to report study results. We have gone from a presentation of the data by gear type to one of an indicator species perspective and have focused on eight species to assess plant impact (Table 1). The plates on the next several pages depict various field sampling operations in our assessment program. l I
m W W W W W m W W m m e e m W W W W Table 1. Summary of indicator species and rationale for their selection to assess impact of Pilgrim Nuclear Power Station on marine life. sesis for Main Bac6 gree. rid Setection es an Sources Sa mling Species Mistory indicator Spacies of lepect Method Anerican tebster RIS d,r,c,s I,E.7/C intoke screans/ trap /trowi/ diving Atlantic silverside RIS d,r 1.E,7/t intake screens /hout sei m Atlantic preheden RIS d,c 1,E,T,G lete6e screens /seim/gitt ret Cumer Rts d.r.s I,E,T/C intake screw / diving /sei.w/ gitt mt/sportfish catch Winter flotsider R!S d,r e,s, t,E inte*e sem/treut/ diving / seine /sportfish catch Pollock RIS d.c,s 1.E tr. a6e screms/ diving / git t mt/spectfish cetd Bluefish 'S c,s T/C civing/gitt mt/sportfish catch Striped bass TS cs T/C diving /gitt net /sportfish catch RIS - representative spacies setected in the originet 316 (e and b) Ntration Dm to assess Pilgeim Statim iwt (Stom and E*bster 1775). IS - f rdicator spacies; was not en originot RtS but ef ter 20 years of data cettection, we ori$=d it to the list. d- a dzeinant specias in the Pilgrim eree. r- e local resi& nt c- comarriet imortance s- recreationet imortance 1- imiet E- entraircent T/C - discherga current effects: thernet/currem C- gas txtbte disease
I III. RPSULTS AND DISCUSSION A. PHYSICAL (ADIOTIC FACTORS) ;
- 1. Power output and Thermal Capacity When assessing impact of the wasto-heat dischargo from pilgrim Nuclear Power Station on fisheries populations in the inshore waters of western Cape Cod Day, it is imperative we consider the I
station's capacity factor (MDC not percent). This index of g g ll operational status approximates thermal loading via the dischargo ; cooling water to the Bay. At 100% MDC, there is an allowable maximum rise (AT) in the discharge water of 18' C (32' F) above ambient temperature. Since commencement of power production ir. 1 November 1972, the annual MDC at the station has ranged from 0.0% in the outago years of 1987 and 1988 to a high of 84.4% in 1985 (Figure 1). Power icvel capacity was extremely low at 0.1% in 1984, which was essentially an outago year. In addition to y,, , , c , , , , , 1985, high output years [ ,, g g
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which ranked fifth overall in " ' ' ' *" ~ ' $ 7" *' ** " ' " "
- the station operational history. a a -=* ='a - *a m C*""q,[5 In this volume, data for Figure 1. Annu.L means and 18 year emulative mean Pilgrim $tetton Unit l Capacity Factor (MDC het selected species collected for "#' "'
the pooled years of 1983, 1985, and 1990 (high operational output) are compared with data from the years of low or no output: 1984, 4 s.
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Plate 4. Fishes caught by gill net in the area of the thermal plume at Pilgrim Station. Gill-net catches include commercibily important species, l e.g., Atlantic cod, pollock, Atlantic mar.kerel, striped bass, and winter flounder. ,
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l 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 I Pilgrim Station on the benthic fish community. l . j' y Yh[i. If h I . I I Ha y
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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 intale trawl station.
1 1 I . j q l l N; "~ li:? $ 3 ! g t l,l Dn:..$y i 4 !} o k { y .y i . l 5 g.7:. + ao o m ,,9 ,% @ k, 4 M (1 (g-.. ! < k.
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- catches can be integrated with impingement data for a more comprehen-I sive evaluation of potential impact on shorezone fishes.
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" indicator" organism to assess stress imposed by the release of the heated effluent.
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. .u ..,.~.v.w.- . u~ , - . w Plate 11. Pictured is the thermal ef fi eet discharging into Cape Lod Bay, and anglers fishing of f the dischsrge jett ies and f rom boats in the plurre B which is visible in the backgr und by the calm water. Striped bass g and bluefish, which are attrac ed to and concentrate in the thermal current, are the dominant species sought by sport fishermen at this location.
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I
I 1986-1989. Through the end of 1990, P11grjm Station has operated at a cumulative capacity of 46.8%, or less than half of its potential. With a relatively low historical operational record, the extent of plant impact on marine life likely has not been realized.
- 2. Discharae current The circulating seawater system at Pilgrim Station induces localized current flows. The once-through cooling water system removes waste heat primarily from the plant's condensor tubes and dischargos it in a current of water to Cape cod Bay. Tho moving water, in and of itself, has a scouring offect along the bottom (i.e., an abrasive action on the benthic environment). There are two circulating seawater pumps at the station; each withdraws 586,739 liters /minuto (155,000 gal / minute) of water from the intako embayment. Ultimately, this water, the primary dischargo flow, laden with vaste heat is discharged back to the Bay. The maximum disci.arge velocity , which occurs during low tide with both circulating pumps operating, is about 2.1 m/sec (7 ft/sec).
Both circulating water pumps were run simultaneously for most of 1983 and 1985 and all but the months of March and April in 1990. During the outage in 1984, both pumps woro off from late March to mid-August, thus markedly reducing discharge flow (Figure 2). In 9 e 1986, both pumps were operated from January to early March; but thoroafter, during the outage, only one pump was operated at a time. As the outage continued into 1987, both circulating pumps were turned of f f rom about late February through early September, I " I
l I! I NUMBER OF PUMPS IN OPERATION y . I I l l I I e L-JMMJSNJMMJSNJMMJSNJMMJSNJMMJSN I teos ses4 toes tese seer NUMBER OF PUMPS IN OPERATION I g _ ..
! I I
om l.lU1lW.L1l J M M J S N J M M J S N J M M J S N 1968 te8e see0 g E Figure 2. Circulating seawater pump operation by I ) month at Pilgrim Station for 1983-1990. 6
while one pump generally was operated for the rest of the time. In 1988, with the outage utill ongoing, one purap was on for most of January-March and June-December, but from mid-April to early June, both pumps were off. In 1989, the plant gradually increased power production as it returned to full operational status. One pump was used in January, February, May and October; otherwise both were run.
- 3. Water Temperature Water temperatures in the study area over the last eight years (1983-1990) were highest in the discharge zone ( Area 3) in 1983 and 1985 (>80% power plant capacity) and in 1990 (> 70% output),
directly attributable to the waste heat (Figure 3). Conversely, i surface temperatures in the impact zone were markedly lower for the outage years: 1984, 1986-88 (poolod), when waste heat had current were minimal. However, in 1989 with Pilgrim's tnormal capacity averaging 28.9%, there was some thermal elevation at the surface and current elevation in the immediate receiving waters. With Pilgrim Station fully operational, the near-field area impacted by the discharge current has included a 1,100-1,400 m'
' denuded' zone, primarily resulting from scouring. A peripheral zone of ' stunted' algal growth of about 1,900 -
2,900 m3 most likely has resulted from the thermal component of the discharge. Recolonization of the discharge area occurred during the recent extended outage, and by 1988, the former ' denuded' and ' stunted' zones had become indistinguishable from the surrounding ' normal' (control) areas.
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5 $ 15 g l IN 7 l O"' U"l "3 " N 10 ? fd 2 2 R
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2 % I'S i W 6 e g WtNTER SPRING SuvuEA FALL M toes a es + 1984, ice +se Qioso GiooO - 89
- 1stLUES REPRESENT AN ArERASE oF TEMPERATtfRES TAKE18 PM AND -
AftOUND THE OfSCHARGE. ouT TO 100m F710M Tsef MOUTH.
+ l filil;c 3p ,
ii[!- .~ Oj'{d r AREA KEY: :f
- 1. GRAYS BEACII & LONG PolNT II l llj qh{g f
- 2. WARREN COVE & ROCKY POINT s
[ h IIII NllIl[/
- 3. DISCHARGE AREA . J b0 hN [) I}
==En ==.m M==. =t
- 4. INTAKE ~~ ~ ~ ~ ~ ~ ~*"""
- 5. WIIITE IIORSE & MANOMET POINT Figure 3. Surface water temperatures in the vicinity of Pilgrim Station averaged by season for the years of high plant operational status (1983,1985. and 1990) and for the transition year (1989).
M M M' M M M M M M M M M M M M M M M
I
~
When Pilgrim Station operates at 100% capacity, an allowable temperature dif ferentia1 n1)proaching 18' C can occur in late summer between discharge and ambient water. The peak temperature in the thermal plume has been 32' C, which was recorded both at the surface and bottom. Conversely in 1984 (outage year) ,1986 (outage April-December), and 1987-88 (outage years), water temperatures in the discharge area mirrored ambient levels. I I I I I I I I I I I I ' I
I I B. IMPACT OF PILGRIM STATION ON INDICATOR SPECIES
- 1. Cunner
Background:
Basis for Selection The U.S. Environmental Protection Agency and the Massachusetts Division of Water Pollution Control selected cunner as one of thirteen representative important species (RIS) to assess environmental impact of Pilgrim Station on the local marine ecosystem (Stone and Webster 1975) . The cunner is an abundant resident fish species in the waters off Pilgrim Station. They are shelter dependent and reside in the rocky areas that abound of f the Plymouth shoreline. A good indicator organism to assess impact of power plant operation, cunner occupy small home ranges in the near-shore marine environment for an extended pericd of time, and, as such, may be exposed to increased fishing mortality (primarily via sportfishing) and potential effects of inshore pollution. Cunner are especially vulnerable at night since low responsiveness, characterizing the sleep state of labrid fish, reduces their ability to initiate an avoidance response to environmental stresses that may occur after dark. A species that occurs in discrete localized populations, such as the cunner, is more likely to be measurably impacted by point-source pollution than a species which is composed of essentially one interbreeding population throughout an extensive geographical range. From our gill not catches, diving observations, and creel surveys at Pilgrim Station, we learned that cunner are dominant 10 I'
members of the groundfish community in the Pilgrim area. The intake's two breakwaters and two discharge canal jetties provide structure for a temperate - water reef community of which the cunner is a member. The large boulders, some with attached macro-algae, provide cover (home sites), which is especially important during the cunner's nighttime sleep phase. Cunner are found normally at depths of between 3 and 10 m but I do occur in deeper waters as far offshore as 100 km southeast of Cape Cod, Massachusetts (Grosslein 1969). Cunner are year-round residents throughout much of their range (Green and Farwell 1971; Olla et al. 1975), dispersing into deeper water during extremely cold temperatures. Ambrose (1870) reported that in St. Margaret's Bay, Nova Scotia, cunner moved into the bay in May, spent the spring and summer inshore, but moved offshore with declining water temperatures in late autumn. In the Gulf of Maine (Bigelow and Schroeder 1953) and off Newfoundland (Green and Farwell 1971), cunner activity gradually decreased as water temperature dropped below 8 ' C. When water temperatures fall to 5-6' C, cunner become inactive and torpid, remaining so until the water warms above 6' C (Olla et al. 1975). Life Stages Impacted and Sampling Protocol The potential sources of Pilgrim Station impact on cunner include mechanical and thermal / current effects. Cunner most likely spawn in the immediate vicinity of the power plant, and because their eggs are pelagic, they and the resultant larvae are subject to entrainment in the plant's circulating seawater system. 11
I Entrainment sampling provides data on the early life stages of cunner in the Pilgrim area. Juveniles and adults occur in the intake embayment at the plant and are subject to impingement on the travelling-water screens. Impingement data routinely collected at the plant and haul seine sampling in the intake provide information on the occurrence and general abundance of finfish in the area on a seasonal basis. The discharge current laden with waste heat and periodically containing chlorine and radionuclidos can affect all life stages of cunner but particularly the juveniles and adults in j the receiving waters. Gill not, observational diving, and sportfish creel sampling provide us with data on cunner in the discharge area and its environs. The gill not and sportfish catches and diving observations revel that cunner are most abundant in summer and fall. Therefore, cunner are expected to be most affected by station operation during those seasons. Review of Impingement and Entrainment Effects Imoincement The Pilgrim Station intake, a shoreline embayment that is i partially enclosed by two breakwaters, appears to influence the impingement of juveniles of larger fish species (> 30 cm TL) and both juveniles and adults of small fishes ($ 30 cm TL) (Lawton and Anderson et al. 1984). Cunner is an example of the latter, and both adults and juveniles are entrapped on the intake screens at I Pilgrim Station. Cunner has been among the dominants impinged at the power plant'from 1976-1980 (Lawton and Anderson et al. 1984) and from 1981-1990. In 1990, cunner were found to be first 12 s
I I impingbd in May and last in November, and over the years have been more abundant in collections from , Tune through September. In 1980, about 1,700 cunner were projected to be impinged at Pilgrim Station. In 1989, the projected number impinged was 241. Although there is evidence for some survivorship c1 impinged cunner (24% in 1989) at Pilgrim Station, an impingement of 1,700 cunner might have a measurable impact on the population in a given year I when combined with sportfishing mortality. See the impingement section in this document for an expanded coverage of impingement data collected in 1990. Entraintnent Cunner eggs and larvae are entrained at Pilgrim Station. In fact, the labrid and Labridae - Limanda groups have dominated the entrainment collections of fish eggs at Pilgrim Station over the years, accounting for over 90% of the total. According to Wheatland (1956), cunner in Long Island Sound spawn from May to October, while Johansen (1925) reported that cunner spawn from May to August in New England and Canadian waters at a temperature range of 10-26' C (Williams 1967). In 1990, cunner eggs were entrained at Pilgrim Station from April-October but were most abundant in June and July. A markedly high density of cunner eggs was collected at the station in June 1989. This might explain the unusually large caount of small cunner observed just outside the discharge canal in 1990. Eggs and larvae of cunner have been entrained as early as March at Pilgrim Station when ambient surface water temperatures have been as low as 2.6' C (Scherer 1984). I " I
I Scherer (1984) proffered that some cunner may ripen and spawn relatively early in waters warmed by Pilgrim Station's thermal discharge. In 1990, cunner larvae were first entrained at Pilgrim Station in May, reaching highest densities in June and July, and then declining through November, when the last larvae were sampled. Unusually large densities of larvae were collected in June of 1989 and in July and August of 1990. Marine Research, Inc. ( 199 0 ) ,. reporting for all fish, stated the projected values for entrainment at Pilgrim Station in 1989 were 7.9 x 10' oggs (46% were from the labrid-Limanda group) and 3.3 x 10 8 larvae. They concluded that these numbers indicate the large quantities of spawn that can be entrained at this power plant during a year and are presumed to be lost from the respective populations. Nevertheless, no appreciable impact on the local cunner population was predicted to occur from entrainment at Pilgrim Station as assessed by Stone and Webster (1975 and 1977), who used flow rates for two units, employing conservative assumptions and ignoring density-dependent compensation for non-entrained eggs and larvae. See the entrainment section in this document for an expanded coverage of entrainment data collected in 1990. Discharge, Intake, and Sportfishing Related Effects Discharae: thermal / current Kinne (1969) reported on the thermal tolerance limits for adult cunner. He found the upper lethal temperature limits to be 29.0* - 30.0' C when acclimated at 18.0* - 22.0* C and 25.0' - 24 I I_
I 26.0* C when acclimated at 1.O' - 3.0* C; the lower lethal limits l were reported to be 5.0* and 0.0* C when acclimated at 18.0* - 22.0' C and 1.0' - 3.0' C, respectively. According to Briggs (1973), the preferred temperature range of adults was 13.3' - 26.1' C. Cunner spawn at temperatures between 10' and 26' C (Williams 1967), while incubation requires 40 hours at 21.1' - 22.2' C and 3 days at 12.8' - 18.3' C. Based on temperature tolerance data, Stone and Webster (1975) predicted that the thermal plume at Pilgrim Station should not result in overt mortality of cunner outside the discharge canal, but during late summer when ambient water temperatures are the highest, there is most likely an exclusion area to cunner within I the 15' isotherm. In the spring, the temperatures in the thermal plume just outside the effluent canal should be optimal for cunner spawning and the hatching of their eggs; while in autumn, the ideal conditions for growth should exist immediately outside the canal. In 1990, cunner dropped from its traditional third too urner emswren scuom uoc too I position hierarchy to of sixth gill in net the catch so
. I; ,
so composition off Pilgrim Station. 4o . [ , There is evidence for population so n
~
, y/ -
so stability in the Pilgrim area o,,,i' ,g,, ' s,1;g,, , ,d, d, ',,,, , o YEAR from 1971 to 1976 (Figure 4), t Jeuwusa c4ren 5 with a grand mean catch rate of
--way oct uoc l Figure 4. Average seasonat standard 5 panet gilt net catch for cunner and respective seasonal MDC 22 Cunner per 9 111 net set. Net % at Pilgrim Stetton, 1973 1990.
I 15 I
I Prom 1977 to 1983, the catch rates almost doubled (grand mean of 41 fish per set), indicating a marked change in distribution or abundance of the local population. The catch rate fell somewhat in 1984 but then dropped precipitously in 1985, remaining at a low level thereafter, with the 1990 rate (4 fish per set) being the lowest of the 20-year time series of data. Over the last seven years, the gill not catch rate of recruitable cunner has more than halved from previous years, averaging 15 fish per set. The pooled grand mean 5-panel catch per unit ef fort of cunner captured during operational years (1973-1983,1985, and 1990) was 63% higher than the average for the two preoperational years of 1971 and 1972. A 9% increase was noted for 1983,1985, and 1990 (high power plant output) over 1984,1986-1989 (outage / low output years). Graphing plant output for the spring-summer seasons, when cunner are active inshore, versus cunner catch rates over the years suggests a possible relationship between these variables (Figure 4). When we statistically evaluated catch / effort data (collected prior to the crash in stock abundance) and seasonal power plant MDC for operational years using parametric testing, we found a significant positive correlation (P S 0.05) and a significant F ratio (P< 0.01) using regression analysis, with 39% of the variability in catch rate explained by variation in plant % I annual MDC (Lawton et al. 1990). Our diving observations corroborate gill net data, lending evidence that cunner (age 1+ and older) of = 5 cm (2 in) and larger 16 . I_
I are attracted to the discharge area. During operational periods, with Pilgrim Station producing a thermal discharge current, our 'I divers sighted more cunner at flood tide in the ' denuded zone' than in the ' stunted' or ' control' zones. Even without waste heat being released, the generation of a current of water produced by at least one of the two circulating seawater punps was sufficient to bring lI i ) about a similar pattern of cunner distribution. By way of contrast, during years when little or no current was released from the power station, more cunner were seen at the reference (control zone) stations. We believe the attraction of cunner to moving water is to feed. Olla et al. (1975) observed cunner to feed both benthically and in the water column. They reported that when cunner feed in the water column with a current present, they face into the current and maintain their position while visually i 1 searching for food to be swept by them. This kind of feeding may go on during the day for an entire tidal cycle, with the isopod, Idotea baltica, being a favorite food item for cunner. This organism i has been found to be abundant in benthic studies at Pilgrim Station. The cunner consistently has been the species seen in greatest numbers by project divers in the discharge area of Pilgrim Station. l In 1990, 53% of the fish recorded in diving records vere cunner, h1 1 A cunner per dive index of 98 was more than double that of 19r9 i (44). This apparent departure from the trend of declining relative l abundance revealed in gill not catches and diver counts since 1985 l can be explained by examining length estimates of cunner sighted in I ' I
I 1990. Over 70% of the cunner sighted in 1990 were 2-3 cm in length, which are young-of-the-year fish. Fish of this size range are able to pass through our smallest gill not mesh (3.8 cm) and are not subject to being sampled by our gill net. The abundance of these small fish suggests a strong 1990 year-class of cunner. They were found at all six diving stations in 1990 but were most common in the control area where 62% were sighted as compared to 28% in the denuded zone. This seems to be contradiction for an operational year when most cunner normally are seen in the path of the discharge current. However, when we look closely, we find that 79% of the cunner sighted in the control area were young-of-the-year fish (2-3 cm); whereas, most of the cunner in the denuded zone were larger individuals. It is known that the very small cunner do not move very far away from their home shelter, and the speed of the current would be too strong for these fish to spend any amount of time in the discharge. Intake Related Effects The intake is a haven for small fishes, in that it offers a I variety of fish habitats, including shallows and a relatively deep channel, sand bottom, vegetation, and boulders, cobble, and gravel. The area also has reduced wave action afforded by the outer intake breakwater. From our haul seine sampling in 1990, we found that juvenile cunner of 2-3 cm abounded in the intake, where 68% of all I the cunner seined were captured. The intake is an ideal nursery l area providing cover / structure and a food supply for young-of-the-year cunner. 2* I l !
Soortfishina Effects over the years, cunner has led the overall sportfish catch at e Pilgrim Shorefront (Lawton et al. 1987). Cunner are easy to catch } and highly available to anglers of f the outer breakwater at Pilgrim l Station because of their affinity to inshore structures that serve as home sites. In addition, they occupy small home ranges for extended periods of time. On the negative side, this exposes the i species to increased sportfishing mortality and also places the fish in proximity to potential results of inshore power plant effects, such as cold shock resulting from plant outages. Most cunner when caught at Pilgrim Station by anglers are allowed to l t die, and fishing mortality can be extensive. In 1983 and 1985, an estimated 2,600 + and 3,500 cunner, respectively, were caught in the sportfishery off Pilgrim Station.
- 2. Lobster
Background:
Basis for Selection The American lobster, a decapod crustacean inhabiting the rock-strewn, ledge, and sand bottoms of Cape Cod Bay, is the object of intensive commercial and recreational fisheries in the viel'..ity of the Pilgrim Nuclear Power Station. This species was selected by the U.S. Environmental Protection Agency and the Massachusetts Division of Water Pollution Control as a species representative of benthic macro-invertebrates to assess environmental impact of Pilgrim Station on the local marine ecosystem (Stone and Webster 1975). The lobster was considered a good indicator species of 19
. I possible environmental disturbances due to its longevity, as it I, takes approximately 7-8 years before the animal reaches legal size in Cape Cod Bay (Bruce Estrella, personal communication). Fertilized lobster eggs, typically extruded in late summer, are carried through the winter attached to the abdomen of the female. Eggs hatch from late spring until summer, whereupon the young lobster enters a three week planktonic stage before finally taking up its permanent benthic existence. For this reason, the lobster was regarded as being representative of bivalves and other benthos with entrainable planktonic larval ntages (Stone and Webster 1975) . Any larval lobster entrainment at Pilgrim would be expected during late spring and summer. Juvenile and adult lobster move somewhat offshore to deeper waters to overwinter. In April, with increasing water temperatures, lobster again appear inshore and remain until the late fall offshoro migration. It is during this nearshore existence that lobster may be impinged at Pilgrim. Life Stages Impacted and Sampling Protocol I Any potential impact of Pilgrim Station operation on lobster would most probably be ascertained by looking at the benthic l dwelling juvenile and adult stages. Entrainment sampling over the years of operation at Pilgrim has produced a negligible quantity of lobster larvae. Intake impingement samples have recorded small I numbers of juvenile lobster over the years, as in 1990, when a l annual total of 55 lobster (mean size 47mm carapace length) were trapped on the intake screens. 20 g
I We typically capture significant quantities of juvenile lobster from May through July during our trawling survey. However, I these lobster data are not helpful to assess power plant impact. Gill not catches of juvenile and adult lobster from May through October are insignificant. To ascertain any impact of plant operation on the local lobster resource, we look to our trap sampling programs: (1) commercial and (2) research. Discussion of the results of these studies for 1990 follows. Discharge Related Effects
. Commercial Lobster Pot-Catch Fishery Pooled lobster catch statistics from the surveillance (discharge) quadrants (H-11, H-12, I-11, and I-12) were compared with data from the reference quadrants (E-13, E-14, and F-13) located in Warren Cove (see Figure 2 in Vol. 1) to assess impact of Pilgrim Station on the local lobster population and fishery.
Realistically, we can compare surveillance and reference area catch rates from the 1984-90 data (1985 and 1990 being the only high output on-line years in that period) because the same lobsterman has supplied all of the data; 1983 catch data are included in our discussion for an additional datum point from an on-line year of the pla :t. Females slightly outnumbered males in the commercial catch from the Pilgrim study area in 1990, co;nprising 52% of the total. This slight preponderance of females also existed at both the l surveillance and reference areas. !I 21 l I
I As in the previous four years, the percentage of culls in the surveillance area in 1990 was markedly lower (17%) than in the referer a area (31%). A chi-square test (Sokal and Rohlf 1969) showed this year's difference to again be highly significant (P 5 0.01). An increase in lobster cull rate is promoted by both lobster fishing and bottom trawl activity (Keser et al. 1983; Estrella and McKiernan 1986). Both study locations are subject to intensive commercial lobster fishing. In addition, in Warren Cove (reference area), commercial bottom trawling is seasonally (November through March) conducted for groundfish; this may account for the continued higher cull rate there. The 1990 mean legal-lobster catch rate (expressed as catch per trap haul, or CTH) decreased approximately 20% at both the reference and surveillance sites (Figure 5). In the surveillance area, CTH fell from 0.41 to 0.32 legals per trap-haul, while the c,7c,,,,,,,, ,,vt reference area declined from ' y ! -
.. e
; ; e 0.34 to 0.27. Annual lobster *
,,. ) [ ]:
- m]
catch rates in the impact area o.e L s
) '
do not appear measurably *E i 5l Q different between years of on- .. e e nos su a was see A-me, ae we. J &, YEAR
... ..o 3
line and off-line plant status, lmac,,, cm.e,] in that the CTH ratios of impact Figure 5, Annual comercial legat tot >$ter catch per trap haul in control and impact areas near versus control sites from the PI(grim Statis , 1983 1990, on-line 'jaars of 1983 and 1985 are comparable with the ratios from the off-line years of 1984 and 1986 (Figure 5). Since 1987, the 2 I E_
I catch rate has been greater at the impact area than the control area, with no apparent relationship in the annual catch ration between these study sites to the annual operational status of the Pilgrim Power Plant. The mean legal catch rate in the discharge (impact) area declined from 1983-1987, thereafter stabilizing with the exception of an upswing in 1989. This trend contrasts somewhat with commercial lobster catch rates and landings for western Cape Cod Bay (Figure 5) and for Massachusetts' coast al waters in ' t,,,, ,,,,,, i general. A cooler ambient temperature regime in 1984 -
.[ - 5 "
co g' 3 [ "" I 4 (Estrella 1985) apparently a y W E , n m r
- a I
04 ?N S' b, Y depressed or at least delayed I kl'l (( h[f. $,, j $A L; $ ja,, k' & n, 9, y M &; - w , the early season lobster molt, *~'
}'f; g d @ Y h [' [, j s .-,
I d,~ r ; n, . which, in turn, would have , a. . i .. , .. . i . . .. . . .. .., ... i... .o YEAR affected recruitment to legal Figure 6. I ccaneretet teget toester catch rates (catch per trap haut per set over day) for size and impeded lobster western Cape Cod Bay, 1981 1990, activity (Campbell 1983; Estrella 1985). The mean commercial catch rate of 0.48 legals per trap-haul in western Cape Cod Bay (Lawton et al. 1985) represented a reduction of 30% in 1984 when compared to 1983 (0.68), 1985 (0.72), and 1986 (0.82) (Figure 6). The legal catch rate then declined decidedly in 1987 to 0.53, spiked to 0.75 in 1988, fell again in 1989 to 0.53, followed by a rise to 0.63 in 1990. Annual legal CTf! in our control area (Warren Cove) did not parallel these data from 1983-1986, but did reflect I 23 I
I a drop in 1987 and subsequent increase through 1990. Actual commercial landings (in pounds of lobster) for all of Cape Cod Bay in 1989 increased 20% from the previous year, which suggests that the relatively low overall commercial CTH value for western Cape Cod Bay in 1989 (Figure 6) may be a sampling artifact (Bruce Estrella, personal communication). According to Estrella (19#5) and Estrella and McKiernan (1986), the coast wide commercial catch rate (catch per trap haul) of marketable lobster in 1984 was lower than in 1983 and 1985 by 19% and 20%, respectively. Record lobster landings were documented along the entire Massachusetts coast in 1985 and 1986 (Estrella and McKiernan 1986). Cape Cod Bay lobstermen had to contend with cooler spring temperatures again in 1987, and a 34% reduction in commercial catch rate resulted. The upswing in the 1988 catch rate in Cape Cod Bay may well have been the result of a l more normal spring bottom water temperature regime. Our selection of reference quadrants changed during the time series of lobster data collectiors. The present reference I quadrants, all located in Warren Cove, have been in use since 1984,
.during which time there were only two years (1985 and 1990) when the plant was fully on-line. Therefore, meaningful impact versus control comparisons to ascertain any potential effect of plant operation on lobster catch rates must await the compilation of additional years of on-line data.
Impact area lobster catch rate data (not normally distributed) and plant thermal output were examined for any relationship using l I I E 1 _
a nonparametric test for association, Kendall's coef ficient of rank L correlation (Sokal and Rohlf 1969). The association analysis p utilized the mean Unit I thermal output for the period of May through November, which encompasses the inshore lobster fishing and l data collection season, versus legal catch rates for the surveillance area during the on-line years (1973-1983, 1985, and 1990). A nonsignificant Kendall's concordance of 0.295 (P=0.85) was found. Earlier in the study, we ran a parametric correlation test of the data from 1973-1983 and found a significant negative correlation (P<0. 05) . As to the limiting effect of current on catch rate, Auster (1985) reported that a water flow above a critical velocity (46 cm per sec) will retard the foraging behavior of lobster by inhibiting mobility. It is reasonable to expect there would be reduced trap l 1 catches in the immediate discharge area, where current velocity can reach over 2 meters per second (7 feet per second) at low tide. In fact, our diving observations have revealed few lobster in the immediate area of the discharge canal. However, a direct cause and effect relationship between the thermal discharge current and the commercial lobster pot catch is difficult to substantiate because we have no control of fishing effort, including the location of traps fished. We have been investigating this relationship in depth with our research lobster study, which is discussed later in this section. In 1988, with considerably more current (though at ambient temperature) emanating from the discharge canal than in 1987, the commercial catch rate of legal 25 l
'~ -
I lobster remained unchanged in the surveillance area. In 1989, with annual thermal capacity at 29% and with one or both circulating water pumps operating, CTH in the impact area increased i substantially, while in 1990, with annual thermcl capacity at 72% and both circulating pumps usually running, impact catch rate declined. These catch rate dif ferences most likely reflect natural year-to-year variability in this area. Commercial gear sampled in the impact quadrants is often deployed far enough out from the discharge canal so that the effluent current is probably not a major factor affecting lobster distribution and resultant catch. In a continuing effort to standardize commercial lobster catch data with our experimental lobster data, the commercial legal lobster catch information in the discharge and surveillance areas were weighted by immersion time (days between pot-hauls) of the pots to generate catch per trap-haul per set-over-day (CTHSOD), a more appropriate measure of catch por unit effort. In 1990, the legal CTHSOD declined slightly from 0.11 in 1989 to 0.08 at the control ara.a, but remained at 0.17 in the impact area. Egsearch Lobster Tran Fish 1DS Research lobster pot-catch sampling was conducted for the fifth consecutive late spring and summer period (June through September 1990). Our objective is to determine whether the operation of Pilgrim Station measurably impacts the local lobster I population. The following parameters were examined: catch rates of legals and sublegals, size frequencies, sex ratios, culls I! I I
I (lobster with missing or regenerating claws), and ovigerous (egg carrying) females. I Table 2. Catch per mit ef fort' f rom research tobster gear in the Pilgrim area for 1990. Legal slied Lobster Sublegal Lobster (182.6 m CL) (<82.6 m CL ) I Area Mean 12 CTHS00 Standard Errors CTH Mean 12 Standard Errors Discharge Area I 0.194 0.180 0.200 2.930 2.870 2.990 (Surveillance) Rocky Point (Control) 0.170 0.160 0.180 3.780 3.710 3.850 Priscilla Beach (Control) 0.210 0,196 0.224 3.060 2.960 3.160 , 'ctH represents catch per trap haut; c1Hsoo indicates catch per trap haut per set over day. 1 We sampled 9,724 lobster from 2,625 trap-hauls in the study area. Catch data for sublegal lobster (Table 2), as measured by catch per trap haul (CTH), averaged 3.30, up from 2.99 in 1990. CTH for legals in 1990 declined s3ightly from 0.45 to 0.41. When weighted by immersion time (days between pot-hauls) of the pots 1 (CTHSOD), which is a more appropriate measure of catch per unit of effort than is CTH for legal lobster, the research trap legal o.."""*"**"""' CTHSOn fell slightly from 0.21 03 ~ fi ' T t 9 f r the study area in
~
oas $ E ; 3 i g oa @ y}'j lii h } ;.c ! :$ p 1 1990. The 1990 legal catch a 3 t s ]! ) , 4 d;- ~g;
- j. o.o* 0.
.:j "p'g
!E rates (Figure 7) declined at el- d(3 IE '
' " ]
lg use mer au wee weo YEAR both control sites (Priscilla . E ENYmt AAEA C Ol4CMARGE
-3 Beach and Rocky Point) but Figure 7. Legal lobster catch rates (CTHsco) remained constant at the impact by area from research lobster gear fished in the vicinity of Pilgrim Station, 1986 1990.
27 g I
I site (Discharge). However, the catch rate of sublegals (Figure 8) was substantially higher than for last year at all three areas (especially Rocky Point). The overall study area sex ou,ao,t e ,ew air, ers ratio of males to females in the M 1990 research catch was 1.2:1 7 _ I(s f7 di (M: F) , similar to 1989 results.
- ..j j'"" .,
0
$ F '
f k, l g _ 1 - l'- s 3 i y g j '
's g7 4 , ,
Actual lobster population sex y J o -{;;g-{ y.
,.;, i - ,,,j ;
; ,p ;;a ratios obtained by SCUBA diving nan su .. .u a . .c .
sampling may vary considerably m .om ., m ,..cm, from trap catch data due to Figure 8. subteget tobster catch rates <ctH) by area from research tobster gear fished in the seasonal changes in trap vicinity of pilgrim station, 1986-1990, vulnerability of females during the molt cycle and mating season (Miller 1987) . Yet, the annual research lobster sex ratio has been relatively constant for the five year study. Lawton et al. (1984a) reported that the overall growth increment per molt for male lobster was significantly greater (P $ 0.05) than for females in the inshore waters of western Cape Cod Bay, which may be due to energy demands of egg production in mature females. The percentage of females ovigerous in the 1990 research data was 1.2% (53 eggers), up from 0.7% last year. Half of these egg-bearing females were from the Rocky Point site. During the five years of this study, no consistent pattern in the distribution of ovigerous females has emerged amongst the sampling zones. The percentage of culls in the research data increased from 27% in 1989 to 29% in 1990. Over the five years, the cull rate has ' 28 l
~
1
I been lowest in the Discharge area. The rate was highcEt at priscilla/ White Horse Beach in 1986 and 1987, at Rocky point in 1988, abo lt equally high at both reference areas in 1989 anci 1990. Our field lobster pot study conducted June through S6ptember for the years 1986-1988 was in effect a modified trial experiment under somewhat non-stressed conditions, i.e., the prolonged power plant outage resulted in no waste heat discharged but tnere was a current flow, albeit reduced to one circulating se6 water pump operating in 1986 and 1988, while flow was sinir.al during the study in 1987. During the 1989 pot study, both circulatinfj water pumps were usually running, while the mean monthly thermal capacity ranged from 16-52%; hence, this was a transitional y9ar as to power plant operation. Data from 1990 are the first collected from a high on-line year, but in July and September there were reductions in heat output to 50% and 22%, respectively. The outage at the plant provided us with a baseline period, where our work became a uniformity trial of fishing standard commercial traps in a standardized manner in the defined study area. As noted in other baited trap studies (Miller 1983) , we anticipated largo differences in catch rates over seemingly homogenous bottom type (see Table 2, control areas). Variance control in any pot stucy therefore becomes paramount (Miller 1986) the less statistical noise, the more ptecise the final impact analysis. Over the course of our research lobster experiment, we have used the same bait, soak time, time of gear haulback and processing, and trap design. The proper pairing of potentially 2e 3 1 I
I impacted / surveillance areas (with stations randomly selected i within) with non-impacted / reference areas was a prime concern. We believe the station pairs selected would reflect natural environmental changes in a similar way. Initial analysis of 1990 legal CTilSOD and sublegal (CTil) lobster catch rates revealed the data was non-normally distributed which could not be satisfactorily corrected by transformation. llence , nonparametric Kruskal-Wallis tests were performed, corresponding to the experimental design of a nested ANOVA (Sokal and Rohlf 1969), using the BMDP statistical software (BMDP Statistical Software, Inc. 1990). To test for differences amongst the three areas in 1990, legal catch rates were initially tested to ascertain if data across months within stations at a site could be pooled. We first had to insure we could statistically pool monthly catch data within a station, and only then would pooling of station data for an area be considered to be valid. At five of the ten stations, the CTHSoo June catch rates were my E o es - g g g significantly less than some or n - t
-e wp fi x
all of the other months, k -h4 probably due d ' lj s , 7 , to the lobster ces j f W!$$ 'Is ; ; A l 5533i S2J a _ 11 spring molt (hence reduced a n, aua su catches) occurring at that time g y"" O ','[^L, g (Figure 9). Therefore, higher Figure 9. Monthly legal lobster catch rates (CTHsco) by area from research lobster gear fished in the vicinity of Pilgrim Station, 1990. g 30
I level testing of catch rates (pooling stations and comparing areas) was not continued. Data analyses subsequently changed from pooling months within statiens to (1) pooling stations within a site on a monthly basis and then (2) areas were contrasted on a monthly basis. As the analyses showed no significant dif ferences (P>0.05) amongst monthly station data at any of the sites, station data were subsequently pooled monthly within each site. Monthly comparisons of legal catch rates amongst the three sites were performed for 1990 data, with no significant differences found between any of the sites. Therefore, we found no measurable impact of Pilgrim Station operation on the legal lobster catch rate at the impact (Dischargo) site in 1990. Sublegal catch rates were similarly analyzed using nested Kruskal-Wallis analyses across months. On the lower level monthly tests (within site by month) for each of June, July, and August, there was always one site with station (s) significantly different (Pso.05) from each other, while in September, there were significant differences amongst the stations within each of the areas. Hence, pooling of monthly sublegal catch rates was statistically questionable. Af ter inspecting the data (Figure 10) , we decided to perform monthly areal comparisons nonetheless, in order to elucidate sublegal catch rates trends by month, with an attached statistical caution. In June, the Rocky Point sublegal catch rate was significantly greater ( P.>_0 . 0 5 ) than that at the other two sites. There were no significant differences amongst the 31 i I
I l sites in July. In August, Rocky Point was significantly greater g than the Discharge site, while in September, Rocky Point was significantly greater than the other sites. Monthly analyses of sublegal catch data from the Discharge area indicated that Station F and Station G had significantly lower sublegal catch rates than other Discharge station (s) in every n.onth but June, when catch rates were low in general. These two stations (especially G) would be the ones most likely to be impacted by Pilgrim Station's thermal discharge current, as they are ,,c,,,,,, , most proximal to the discharge , . k_ 7 canal (see Figure 3, Vol. 1). e -
~
R rid g
%, y E Y g q.
We hypothesized that the rpeed * , x R s. ! # % g iy h.# s 'm ; Y s (' of the bottom dir. charge current f j$ j}] M I is E g._._ gl. ;.6... g at these stations may have an WONTH impact on sublegal catch rates as aocu ,omi cn .c .au I am eni.cu. ca .a ....no E by reducing the mobility of Figure 10. Monthly subtegat tobster catch rates (CTM) by area from research tobster gear fished small lobster (Auster 1985) and in the vicinity of morte station, m, thus reducing their relative abundance at these sites. This study provided us with an opportunity to examine if a relationship exists between the discharge area research catch data and Pilgrim Station thermal output (as an index of plant operational level) within a season. The nonparametric Kendall's I coefficient of rank average correlation was performed for 1990 ' data. Average Unit I Pilgrim Station Capacity Factor (MDC Net %), calculated for those days when the pots in the discharge were 32 g
N ~ fishing, was correlated with sublegal catch rate and then with legal catch rate per sampling day for each of the Discharge stations. There were no significant associations found between plant operational level and catch rates for any station. However, a nearly significant (P=0.06) association between sublegal catch rate and MDC was noted at Station G over the sampling period in 1990. To summarize, sublegal catch in 1990 was shown to be usually lower at Station G than at the other discharge stations by Kruskal-Wallis analyses. l Another quantitative approach to ascertain Pilgrim Station impact has merit. Limited to a single impact site (treatment) and having two control sites, we used the extended outage (pre-stress) period to establish the relationship between stations, using the ratio of the biotic measure obtained at the treatment site to the average of the two control sites. Future changes in this ratio could then potentially indicate plant impact on the local lobster population. This follows the methodology suggested by Thomas and Van Voris (1986) for power plant environmental impact assessment, wherein the intrinsic ' impossibility' of finding identical control locations is recognized, and therefore trend alterations in the resultant impact / control ratios are monitored. The grand mean ratio for legals was 0.826 and for sublegals was 0.819 for the three outage years. For 1989, a lower power production year, the ratio for legals equaled the three-year average, 0.826, whereas the ratio for sublegals climbed to its highest value, 0.910. For the full power year 1990, the legal ratio was 1.021 and the sublegal 33
I ratio stood at 0.857. Assessment of the significance of those ratios cannot be done without more data from high on-lino years. With additional year (s) cf on-lino data, we can compare the annual research lobstor catch rates from the dischargo (impact) area betwoon on-line versus orf-lino periods. Wo viewed 1989 as a low power generation year relative to annual plant output (39%) and, therefore, could not assign the lobster catch data as being from an on-line year for the research lobster study.
- 3. Strined bass and Bluefish I
Background:
Basis for Selection Stripod bass and bluefish are among the most prized fishes of inshore recreational and commercial fishermon. Tbo former is native to most of the East Coast of the United States, ranging from northern Florida to the St. Laterence River, Canada. The latter is native to both the European / African and American coasts, ranging along the western Atlantic from Argentina to Cape Cod and occasionally to Maine and tiova Scotia. The Massachusetts Division of Marino Fisheries (1977) found that stripod bass and bluefish were among the top throo species sought by anglers in Massachusotts. Bluefish and stripod bass have ranked one and two as the top game fish in popularity at the Pilgrim Sta tior. 's Ghorefront over the years, overall the bluefish has ranked second and stripod bass fourth in number of fish caught in the sportfishery at Pilgrim Shorefront (Lawton et al. 1987). Wo havo I 34 1 I_
I colected them as indicator organisms to assess impact of the thermal discharge from Pilgrim Station. From our croel surveys , diving observations, and gill not catches, wo learned that both bass and bluefish are seasonally abundant in and around the Pilgrim discharge area. Both game fish are attracted to areas of moving water (e.g., rips and currents) where the velocity of the water incapacitates forage fish rendering them casy prey (Woolner and Lyman 1983) . When operational, Pilgrim Station's thermal discharge is a continuously flowing, artificially created thermal current that has been found to attract and concentrato bass and bluefish (Lawton et al. 1987). Stripod bass and bluefish are spring to f all migrants that move inshore in Massachusetts in April and May fe>r the former and May to June for the latter, with of fshoro migrations occurring normally in October for bluefish and in November for bass. The seasonal warming and cooling of coastal waters are the key to the annual migration patterns. In the spring, bluefish arrive in southern New England when the surface water temperature warms to 12-15' C, while the fall omigration begins when the water temperature falls below 15' C (Lund and Maltezos 1970) . Striped bass, three years of ago and older, use nly migrate northward in the spring and return south in the fell, when waters cool. Bass natal to the Hudson River generally do not migrate beyond Cape May to the south and Cape Cod to the north; whereas, bass spawned in the Chesapeake Bay compicx may conduct lengthier migrations. Although bass, in low numbers, have been known to overwintor in 35 g I
l I certain southern liew England rivers, most migrato south, with some spending the winter in the mouth of tho liudson River and others overwintering off the New Jersey coast or in the Delaware and Chesapeake Bays. Life Stages Impacted and Sampling Protocol The potontial sources of Pilgrim Station impact on bluefish and striped bass include impingemont on the plant's intako screens and thermal or current offects. Entrainment of their eggs and larvao is not a concern at Pilgrim because neither species spawns 1 anywhere near the plant. Striped bass spawn in rivers and brackish areas of ostuarios from spring to early summor, with the major spawning areas for the entiro East coast being the Roanoko River-Albermar30 Sound in North Carolina, the lludson River in New York, and Chesapeake Bay complex of Maryland. The early development of bass occurs within their natal river, and its not until their third spring that bass emigrato to the Atlantic Ocean. Bluefish spawning occurs primarily of fshore with two major spawning periods along the U.S. Atlantic coast - in spring (March-April) in the south Atlantic I Bight near the edge of the continental shelf and in summer (Juno-July) occurring between Cspe flatteras, North Carolina and Now England over the continental shelf. Bluefish larvao, which are transported by prevailing curronts, enter shoro-zono nursory areas along the mid-Atlantic coast as juvenilos (snappers) during summor. There is the pctential for impingement of juvenilo bluefish at Pilgrim Station. However, to dato, the numbers of 'anappers' impinged have been extremely low. I 1 I_
I The thermal discharge at Pilgrim Station can affect the juvenilo and adult stages of both species in the receiving waters. Gill net, observational diving, and sportfish croel sampling provido us with data on bass and bluefish in the discharge area and its environs. While haul scino sampling in the Plymouth area, we have occasionally captured young-of-the-year bluefish. Review of Impingement and Entrainment Effects lio stripod bass have been impinged at Pilgrim Station. Over the years (1973-1990) since Pilgrim Station began commercial j operation (1973), only four bluefish (all young-of-tho-year) have boon sampled in impingement collections. Two (51 and 67 mm TL) woro collected in Juno 1977 and 2 (90 and 115 mm TL) in 11ovember 1982. Both species are strong swimmers and generally can avoid impingement. Entrainment tio striped bass and bluefish eggs or larvae have boon entrained at Pilgrim Station, and it is not likely to happen because of the life history strategios of the two species. Discharge, Intake, and Sportfishing Related Effects Di sch a rcte : thermal / current Bluefish ! During the entire period of environmental studies at Pilgrim Station, bluefish have been seasonally abundant in Massachusetts coastal waters. Bluefish were not caught in the Pilgrim area before June, with the first ones being taken in the thermal plume. 37 I
I Bluefish arrivo inshore when the water temperature warms to 12'-15' C (Lund and Maltoros 1970), and they are seldom abundant in waters coolor t' nan 15.6'
. C. For examplo, in 1985, with Pilgrim Station fully operational, bluefish were first caught in Juno in the thormal plume at water temperatures of 15' C on the bottom and 19' C at the surface. According to olla and Studholme (1971), the preferred temperaturo range of bluefish is 19-22' C, and because of this, there is probably an exclusion zone to bluefish at the mouth of and just outside Pilgrim Station's discharge canal in August as a result of high temperatures.
Conversely in the fall, the thermal elevation of the cooling water at Pilgrim Station has, at times, prolonged the stay of bluefish in the rocciving waters of Cape Cod Bay buyond the fish's I normal tino of departure from inshore waters. In 1985, bluefish woro last caught in lato November by anglers fishing in the thermal dischargo. Water temperatures in the heated outflow, at the time, were 10' C on the bottom and 17' C at the surface. Adult bluefish are known to survive temporarily at a water temperature down to at least 7.5' C (Lund and Maltezos 1970). With the plant fully operational, Pilgrim Station's thermal offluent is a continuously flowing, artificially created warm-water current of sufficient velocity to attract and concentrate bluofish. Lyman (1974) reported that bluefish are attracted to moving water (e.g. , tidal rips and currents) . Lund and Maltezos (1970) observed that bluefish will como to the surface at dawn to food and will continue fooding until the tidal flow wanos or light intensity I I l
I l increases. They further documented that on foggy days, bluefish often stay at or near the surface to feed until the current slacks. That bluefish are attracted to the discharge current from Pilgrim Station is readily apparent when we examine the data from our various sampling programs. Their numbers generally are low in i the Pilgrim area when the plant is not operational or only discharging a water current of relatively low velocity. Pilgrim Station increased its annual MDC from 29% in 1989 to 72% in 1990, and with that the gill net catch rate of bluefish at the edge of the plume rose from 0.5 to 2.5 per set, respectively. The pooled grand mean 5-panel gill not catch per unit effort of bluefish for 1983,1985, and 1990 (years of high power plant output) was 45% higher than the overall average for 1984,1986-1989 (outage or low output years) despite the coastwide trend of declining catches of bluefish (commercial and recreational) from Maine to Florida over the period of 1980 to the present (NEFC 1989). Although bluefish never have occupied a pcsition of dominance in our diving records from of f the power plant from 1981-1990 (i.e., no bluefish were observed by divers from 1984-1988), they were sighted in 1983, 1989, and 1990 (years of at least partial station operation). Eighty-five percent of the bluefish have been observed in the discharge zone compared to ' control' or ' stunted' zones. Our index of relative abundance (fish per dive) rose from 1.5 in 1989 (relatively low output year) to 21.0 in 1990 (high operational year) . During an observational dive in the area of the discharge in late September 1990, we sighted an aggregation of iI I
I about 85 bluefish moving in a long oval pattern in the thermal plume. Power generation at Pilgrim Station has been interrupted by numerous outages that have negatively impacted sportfishing at the Shorefront area. The absence of a strong thermal discharge current has resulted in marked reductions of sportfish catches of bluefish in the outfall area. At the time of a plant outage during most of September and October 1975, only 14 adult bluefish were caught by sportfishermen at Pilgrim Shorefront as compared to over 500 in 1973 and 700 in 1974 for the same months, when a strong thermal current was present. An estimated 1,000 bluefish were taken by anglers off the plant in 1983 and 2,200 bluefish in 1985, years of high plant output (> 80% thermal capacity and two circulating seawater pumps in operation) . Conversely, with the absence of waste heat and a marked reduction in flow of water out the discharge canal during the summer and fall seasons of 1984 and 1986-1988 (outage periods), the catches of both bluefish and striped bass fell to about 100 fish in total for all four tishing seasons. During the July and August creel survey of 1989 (transitional year), the catch of bluefish, although relatively low, showed a slight upswing from the previous three years, with a total of 68 bluefish landed. It is noteworthy that divers sighted bluefish in I the discharge area in 1989 for the first time since 1986. During the Mey-August creel survey in 1990 (high operational year), the sportfish catch of bluefish comprised 55% of the total catch at the 40 l, I
I Shorefront, numbering 312 bluefish ( no quantitativo data obtained from September through November). We conclude that the operation of Pilgrim Station has a positive offect on bluefishing in the Pilgrim area via the attraction the thermal dischargo current has for this game fish, concentrating them for extended periods of time at a point source within casting distance from shore. However, on the negativo side, I this attraction to the outflow may increase the potential for bluefish to be stressed via heat or cold shock and gas supersaturation. For example, at the Northport power plant, in Long Island, New York, bluefish that were overwintering in the l plant's thermal discharge were cold shocked and killed one January during an outage when exposed to cold winter ambient water temperatures of Long Island Sound (Jonsen 1970). A similar occurrence is possible at the Pilgrim Station site. An incident involving bluefish occurred at Pilgrim Station in late August 1978, when an estimated 2,000+ fish, mostly clupeids l (herrings), died in the thermal plume, many presumably from heat shock. It appeared that bluefish present in large numbers at the time in the Pilgrim area, chased these fish into the seaward end of the discharge canal, thereby exposing them to lethal temperatures. Another incident at Pilgrim Station occurred in September 1985 when L large numbers of adult bluefish chased and trapped a large school I of adult Atlantic menhaden in the mouth of the discharge canal up as far as the barrier not. A feeding frenzy went on all morning I 41 I
I and into the af ternoon, with sono menhaden appearing to bo stressed by the high temperatures of the thermal discharge. Strit,ed bass From Chesapeake Bay to Now England, seasonal bass migrations occur along the coast. Chesapeake Bay once produced 90 percent of the mid-Atlantic striped bass when stocks were plentiful, but today it produces about 65-75 percent, with the lludson River contributing a higher porcent than in the past to coastal migrating fish (phillips 1990). Striped bass tolerate cooler temperatures than bluefish and are active at water temperatures between 7' and 21' C (Smith and Wells 1977). There is probably an exclusion zono to striped bass in the botter part of the t.hormal plume at Pilgrim Station in August because of high temperatures. Catches of bass from all gear types are practically nil in the dischargo area in August. When coastal waters cool below 7' C, bass migrate to warmer water; whereas, prolonged exposure to temperatures above 27' C is probably lethal (Smith and Wolls 1977). Over the years, bass have been present in the Pilgrim area from May through November. I It is generally accepted that a successful spawn of stripod bass, producing a dominant year class in the Chesapeake Bay estuarine complex, has a pronounced of foct on subsequent numbers of bass occurring at distant points along the Atlantic coast. Records from Maryland's Department of Natural Resources showed that annual peaks in their young-of-the-year survey index for striped bass matched similar peaks three years later in the commercial catch of this species (Walters 1987). There was a dominant year class of 42 I a
I stripod bass produced in Chesapeake Bay in 1970 which resulted in banner commercial landings in 1973. Sportfish catches of bass woro I relatively high at Pilgrim Shorefront in 1973, when this species was the dominant fish creolod, but subsequently declined through the 1970's and early 1980's. Loyols of bass reproduction in Chesapeake Baj woro generally low from 1971-1988, with the exception of 1982, when modest numbers of juvenilos woro produced. In 1989 the Maryland survey pointed to high juvenilo bass production, indicativo of a long overdue dominant year class. The prolonged period of reproductivo failure had resulted in a steady decline in bass abundanco. From a record high of 6.7 x 106 kg (14.7 million pounds) of bass landed in 1973 along the Atlantic coast, the commercial catch reportedly declined to 7.7 x 10 5 kg (1.7 million pounds) by 1983. The lludson River stock did not experience the same decline as Chesapeako bass but instead had very high juvenile production in 1987 and 1988. Striped bass have boon caught in the Pilgrim area from May through November, primarily in the discharge area, with greatest numbers taken in Juno and October. Cape Cod Day historically has been the contor of stripod bass abundance in the Gulf of Maine. Bass, like bluefish, are attracted to moving water and will ontor a current to feed when the flow is pronounced, withdrawing when current speed wanos (Woolner and Lyman 1983) . Our gill net catches and creel survey data generally mirrored stripod bass stock abundance lovels along the Atlantic. The sportfish catch of striped bass at Pilgrim Station peaked at 650 fish in 1973, I ' I
I i declining to less than 40 bass angled both in 1974 and 1975. The gill not catch rate of bass was 6.6 fish por sot in 1973 but thereaf ter declined throughout the 1970's, ranging f rom 0.0 to 0.6. During the first half of the next decade, gill not catch rates remained low ranging from 0.0 to 2.6. A moderately successful year-class was hatched in Chesapeake Bay in 1982 and, protected by management regulations, was in evidence in the 1985 gill not catch rato as it rose to 5.3, the highest in over 10 years. This was also reflected in the 1985 sportfish catch at the Shorofront which was almost 400 bass landed. The lattor represents a ten-fold l increase in sportfish catch from 1974 and 1975. Pilgrim Station's warm-water discharge has been found to attract and concentrate stripod bass. Thoir numbers generally have been low in the Pilgrim area when the power plant is not operational and discharging a noticeable current of water. Pilgrim Station incronood its operational capacity from 29% in 1989 to 72% in 1990, and the gill not catch rate of bass increased from 0.4 to 7.1, respectively. The pooled grand mean 5-panol gill not catch per unit effort of bass captured during the high operational years of 1983,198b, and 1990 was 88% higher than the grand mean for 1984,1986,1989 (outage or low output years). Diving observations in the 1980's corroborate gill not findings. During 10 years of diving off the plant, 97% of the bass have been seen in the discharge current. An index of 34 striped bass per dive (481 base total) for 1990 is the highest recorded in our study. Bass (148) were also observed in abundance by divers in 44 g, n.
1985 at 12.3 fish per dive. No bass were sighted in 1984, 10 in 1986, 1 in 1987, and none in 1988 for a total of 11 bass for these outage years at the plant. In 1989 (transition year in plant operation) 52 bass were observed at a rate of 4.3 bass per dive. Sportfish catches in the 1980's were also tied to station operation. With the absence of wasto heat and more importantly a marked reduction in flow of water through the discharge canal during the fishing seasons of 1904 and 1986-1988 (outago periods), I the pooled sportfish catches at Pilgrim Shorefront of both bass and bluefish totaled only about 150 fish for all four years. Conversely, during high operational years, 150+ bass were caught in 1983, almost 400 in 1985, and 150 in 1990. Ample access for anglers at the Shorefront and the attraction of bass to the discharge current is a boon to sportfishing in the Plymouth area. However, bass are also subject to the same potentially negative impacts of the thermal discharge as bluefish. Intake Related Effects The intake, as a haven for small fishes, has hold l concentrations of young-of-the-year bluefish (snappers), which are subject to plant impingement and back-Vash effects. Soortfishina Effects Bluefish and striped bass have ranked second and fourth, respectively, in sportfish catch over the years at Pilgrim Station. We conclude that the operation of Pilgrim Station has a lI 1 concentrating effect on bass and bluefish distribution. This, in turn, has a positive effect on the sport fishery off Rocky Point by I 45 !I
I massing numbers of both species for an extended period of time at a point source within casting distance from shore. However, this concentrating effect can substantially add to the exploitation rate, as sport fishing can comprise a sizable part of fishing mortality for some species (Williams et al. 1983). Over 2,000 bluefish and over 600 striped bass have been caught by shore-based anglers in a given year at Pilgrim Station.
- 4. Atlantic silverside
Background:
Basis for Selection The Atlantic silverside is an abundant forage fish ranging from New Brunswick to Florida which typically inhabits shallow marine and estuarine waters in large schools. Silversides mature at age 1, with only a small percent of the population surviving to two years of age. Spawning in the Massachusetts Bay area occurs from late April through June at water temperatures of 9-21' C in estuarine locations (Conover and Kynard 1984), while spawning has been documented in a Connecticut estuary f rota May * 'h July (Cadigan and Fell 1986). Silversides have been documc. . be a multiple batch spawner, with ferales spawning up to four t c ;s over a season. These spawning events occur intertidally ori i two-week cycle synchronized with the lunar cycle at the time of the morning high tide (Conover 1985; Middaugh et al. 1984). The eggs are I adhesive and, in Massachusetts Bay estuaries, remain attached to mats of filamentous algae at the high tide mark (Conover and Kynard 1984). 46 1 I_
.__ ~__.___ _____ _ _._ -_ -- - - - - --
I Most adult silversides in 11ew England waters undergo an offshore late fall migration to overwinter in waters as deep as 50 meters on the continental shelf as inshore water temperatures decline below 6' C (Conover and Murawski 1982). Conover and Ross (1982) estimated overwintering mortality of Massachusetto silversides to range from 88% south of Cape Cod to 97% north of the Cape. They postulated a population density compensatory mechanism was in effect, wherein size-selective winter mortality f avored the survival of large individuals. Year-class strength, however, was negatively correlated to the mean size of silversides prior to l overwintering. The number of adults found to be returning to inshore waters in the spring (spawning stock) appears to remain relatively constant regardless of the previous fall population size, as fish from less abundant year-classes exhibit lower winter mortality than dominant year-classes due to their larger mean body size. Atlantic silverside was selected by the United States Environmental Protection Agency and the Massachusetts Division of Water Pollution Control as a Representative Important Species (RIS) as it is an abundant forage fish which is resident in the immediate vicinity of Pilgrim Station (Stone and Webster 1975). Silverside abundance is greatest in summer and early fall. The local population likely spawns in the nearby Plymouth, Kingston, Duxbury Bay estuary. Juveniles and adults could be affected by the thermal discharge plume and by impingement on the traveling screens. I . I " I
I Coar Types and Life Stages Affected Any potential impact of Pilgrim Station on the Atlantic silversido population most likely would be due to juvenile and adult impingement. Silversido oggs wore not often entrained at Pilgrim Station, and larval entrainment has boon minimal during the years of plant operation, our haul seino sampling program captures juvenile and adult silversides in the Intake which are potentially susceptibio to impingement. The other seining stations provide some index of annual silversido abundance in the Pilgrim area. The gill not and trawl sampling programs capturo very low numbers of silversides. Review of Impingement and Entrainment Effects Sox determination of silversides is a temperaturo influenced I phenomenon affecting larvao during a critical period from 32 to 46 days af ter hatching (conover and Fleisher 1986) . Cold fluctuating water temperatures of 11-19' C produce a majority of females, while warmor temperatures of 17-25' C result in a proponderance of malos (Conover and liynard 1981) . Silversides would be unlikely to spawn in the protected waters of the Intake due to the lack of suitable substrato for egg attachment. llence, the possibility of silversido ogg and larval entrainment with resultant thermal porturbations and potential alterations in temperature-dopendent sex ration is minimal at Pilgrim Station. Entrainment data collected at Pilgrim Station by Marine Research, Inc. from 1980 to 1990 show a low incidence of silversido larvac. Austin et al. (1975), while investigating the potential impacts of a nuclear power plant in I I
I 14ong Island Sound, demonstrated that silversido larvae acclimated to 20' C (similar to Cape Cod Bay summer temperatures) underwent minimal stress when exposed to elevated temperatures of 34' C. Hence, some of the entrained silverside larvae at Pilgrim Station may survive the thermal shock associated with passage through the cooling system. Conservative estimates of annual equivalent adult silversido losses from Pilgrim Station operation, based on fecundity and egg survival estimates, are 187,000 fish por year by impingement and 8,000 fish per year by entrainment, for a total of 195,000 individuals from the population (Stone and Webster 1975). Such a speculative loss appeurs largo, but based on the abundance of the species (17,500 captured in our 1990 seining program alone) this may not have an appreciable effect on the population. Discharge Related Effects Adult silversides acclimated in the laboratory to water temperatures of 14' and 21' C had lethal temperatures of 25' and 30.5' C, respectively (Hoff and Westman 1966). Based on these temperature tolerance data and the projected thermal plume of Pilgrim Station, adult silversides were projected to be excluded from an 4.5 ha site in the discharge area in summer (Stone and Webster 1975). The effects of the thermal plume are probably l minimal to Atlantic silversides due to their high abundance in the region, the relatively small size of the thermal exclusion zone, and the species ability to siinply move to avoid stressful temperatures. g 49 M' I
Intake Related Effects In 1990, Atlantic silversides comprised 88% of the total haul soino catch at all sites combined. At the Intake, the silversido catch reprocented 36% of the total seine catch for that sito. This is the usual annual pattern in the seino data, as the Intake catch typically also reflects, depending on the year, largo catches of river herring, menhaden, and/or sand lance. The annual silversido catch por set for all seine stations pooled decreased from 236 fish per set in 1989 to 216 in 1930. The silverside catch por set in 1990 in the Intake remained similar to last year's value, Warren Covo showed a pronounced increase, while the romaining sitos (Long point and Manomat Point) exhibited noticeable decreases , , , , , , , , , 9 ione (Figure 11). ,, , our haul seine data from eoo . the past decade has consistently "' ' shown silversides to be dominant specios at all stations the brM d "" ' "" "" "" EAn sampled, representing well over 5 ,5,*,",'.$' S ', ~.*o',7,"lo,,,, 80% of the annual catch (Lawton Figure 11. Mean catch per stanoord haut seire set of Attentic silverside collected along the et al. 1989). At the Intake etym uth shorettne, weitern e.ne e d sey, 1984 1970, site, haul seino catch data of silversides for the months of sampling (June through November) consistently have shown a dearth in abundance of this species in June, high abundance from July through September, and then a decline through November. I 50 m.
I Pilgrim Station impingement data has consistently shown the silverside to be a dominant species impinged with most collected in I the colder months of the year, November through April (Lawton, Anderson et al. 1984). These are adult fish which were overwintering in the Intake embayment. The monthly mean size of silversides impinged has ranged from 9 to 11 cm total length. Conditions in the deeper waters of this sheltered site are apparently adequate for silverside survival during winter conditions. It is during the time of peak silverside abundance in the summer that their impingement is nearly nonexistent at Pilgrim Station. conversely, peak silverside impingement occurs in winter when numbers inshore are low, perhaps due to reduced mobility of the overwintering fish at low ambient temperatures. I 5. Atlantic menhaden Background Basis for Selection The Atlantic menhaden is an open water migratory species comprising a single population ranging from Nova Scotia to Florida. Most menhaden mature at uge three, with spawning occurring on the continental shelf and in the larger full-salinity bays (Bigelow and Schroeder 1953). The spawning neason off New England runs from j spring through fall with a peak in June and July (Scherer 1984) . The buoyant eggs hatch within 48 hours, and the young larvae soon move well up into the low-salinity regime of coastal estuaries (Young 1974). These one inch larvae grow and metamorphose into juveniles, with a concomitant switch from discriminant 51
l l phytoplankton feeding to generalized, omnivorous zooplankton l grazing. Juveniles school together and move out to the higher salinity waters within an estuary, where they remain until the decreasing water temperatures of fall trigger a southward coastal migration to offshore wintering grounds of the southeast Atlantic coast. During the spring migration, individuals move north and stratify themselves along the coast by latitude according to age or size during summer (111cholson 1978). This brings schor' of menhaden back to the Massachusetts coast in April as ocean waters warm above 10' C. Henhaden over two years of age move further north, with few three year-old fish found south of liew Jersey. The largest concentrations of schooling menhaden from s,pring through fall are found within 24 kilometers of shore. Atlantic menhaden are the object of a substantial commercial fishery along the Atlantic coast, accounting, along with Gulf menhaden, for over 50% by weight of all fish landings in the United States ( Atlantic States Marine 71sheries Commission 1979) . This enormous menhaden catch is processed entirely for use in livestock and poultry feed and for industrial applications such as paint and ink manufacturing. In the 1950's, the menhaden population was comprised primarily of three through eight year-old fish. With increasing fishing mortality in the 1960's, fish less than three years of age constituted the majority of the coastal stock. This I situation improved in the 1970's with a few strong year-classes recruiting to the population. Monhaden have historically been I s2 I 1 I_
1 I subject to wide fluctuations in year-class strength (Bigelow and Schroeder 1953). The menhaden was selected by the United States 1:nvironmental Protection Agency and the Massachusetts Division of Water Pollution Control as a Representative Important Species (RIS), typical of most clupcids and other migratory species, to assess impact of Pilgrim Station (Stone and Webster 1975). Menhaden are sensitive to environmental stress resulting from environmental perturbations. Young (1974) provided specific examples of detrimental impacts of coastal power plants on Atlantic menhaden. Gear Types and Life Stages Affected Any impact of the operation of Pilgrim Station on Atlantic menhaden local 3y would most likely be due to juvenile impingement, perhaps some egg and larval entrainment, and gas bubble disease (GBD) affecting adults and juveniles in the thermal discharge plume. Our haul seine sampling program captures juvenile menhaden in the Intake embayment; these fish are potentially susceptible to impingement on Pilgrim Station's intake travelling screens. Gill net sampling has produced relatively low numbers of adult and juvenile menhaden. The fish overflight program is geared specifically to identify large schools of clupcid fishes, such as menhaden, which may become impacted by Pilgrim Station via impingement, or by GBD from temporary residence in the discharge plume. I I 53 l { I
I Review of Impingement and Entrainment Effects Atlantic menhaden spawning in Capo Cod Bay proper has been inferred from fish larval and egg monitoring studios conducted around Pilgrim Station from 1974 to 1976 by Marino Research Inc. (Schoror 1984). Manhaden oggs and larvao woro found at low densities. The buoyant eggs were found from April through October, while larvao woro collected April until December, with larval abundance peaking in July of those years. Actual entrainment of menhaden eggs through Pilgrim Station during years of operation has boon relatively low, while larval entrainment has been rare. In 1990, oggs were entrained from June through October, with highest densitics in Juno and July. g 1 Impingement of juvenilo menhaden on the intake scroons at g ll Pilgrim Station has been relatively light. In 1990, for examplo, , only 345 menhaden (size rango 61-114 mm TL) woro sampled, with most collected f rom September through December, corresponding to the timo juveniles leave the estuarine nursory grounds on their southward migration. Haul seine catch data from the intake from I 1981 through 1990 reflect periodic largo catches of young clupeids (menhaden / river horring) betwoon September and November of some years; these are fish potentially subject to impingement. In 1990, however, menhaden were absent from seino catches in the intake. Stono and Webster (1975) conservatively estimated, via a Ricker stock and recruitment function, that lossos to the menhaden population from entrainment and impingement at Pilgrim Station are negligible to the population. 54 g i
Discharge Related Effects Annual gill net catch data y ,u o, , ,,,c ,c , , ,,,y,, ,3e 10r r from 1971 to 1990 for adult , ,
],100 ,
L menhaden have shown depressed ,
- ' l
]
k
~
catch rates cince 1980. No 4 - -
~
relationship between plant "~9 1_
'Ir]
,k_._,m 1 1, Lt I d'Dl" .
operational status and annual * ' ' " "" "" S'y*" y *" *" *" , mean menhaden gill not catch can ltawawwaosacAten -sAwwustuocl be discerned from a plot of Figure 12. Mean annat 5 panet gilt net catch l these variables (Figure 12). of frenhaden ard annuai 1 MDC operational Levet at l The maximum tolerable temperature for juvenile menhaden is 33' C (Young 1974), while adults acclimated to 15' C tolerated temperatures up to 31' C (Battelle Memorial Institute 1972). The preferred temperature range for adult menhaden is 10'-21' C (Stone and Webster, personal communication). While undergoing spring northward migrations, menhaden have on occasion been attracted to the Pilgrim Station discharge canal as thermal plume temperatures were within the species' preferred range. Summer and early fall discharge water temperatures exceed the menhaden's preferred maximum, thus minimizing attraction to the thermal ef fluent during these times. However, in August 1975, about 3,000 menhaden died in the thermal plume at Pilgrim Station because of the combined effects of thermal stress and gas bubble disease (GBD). Cooling waters from power generating stations can became supercaturated with dissolved gases, and fish residing too long in this supersaturated water 55
develop gas bubbles in their blood and other tissues which cause blockage, rupture, and eventually can lead to doeth. Sizeable mortalities of adult menhaden temporarily residing in the Pilgrim discharge canal occurred in April of 1973 ana 1975, with GBD ascertained as the etiological agent (Lawton et a1. 1986). Lawton et al . (1986) dotormined that f.issolvr;d gas naturations are highest in spring and early cuiniar at the Pilgrim Station discharge in conjunction with increasing ambient water temperature and concomitant decreasing gas solubility. In particular, potentially lethal dissolved nitrogen gas saturations (2115%) occur in the cooling water dischargo at Pilgrim during the menhadon's inshore sojourn from April to November. A fish barrior not has been in place in the discharge canal sinco fall 1973 to provent access to the top two-thirds of the canal, thus limiting the potential of any future major occurrence of GBD incidents. Stock-recruitment modeling of the menhaden population incorporating annual GBD mortalities experienced at Pilgrim Station in 1973 and 1975 revealed a negligible impact on the overall menhaden resource (Stone and Webster 1975).
- 6. Winter Flounder
Background:
Basis for selection Winter flounder is a familiar resident of bays and estuaries located along the Atlantic coast from Labrador to Georgia, with its greatest abundance occurring from the Gulf of St. Lawrence to Chesapeake Bay. Bigelow and Schroeder (1953) described winter 56 _I .
I flounder as the most common shoal water flatfish found in the Gulf of Maine. Exhibiting localized seasonal onshore-offshoro I migrations in response to changes in temperaturo (McCracken 1963), winter flounder are otherwise a fairly stationary species (Bigolow and Schroeder 1953; Lux et al. 1970; }!owo and Coates 1975; Pierco and Howo 1977i Klein-Macphoo 1978). Perlmutter (1947) described 1 the coast wide wintor flounder population as being comprised "cf I many independent localized stocks"; in the Pilgrim Station area, the principle spawning area is believed to be the Plymouth, Kingston, Duxbury Bay (PKDB) complex (Stono and Webster 1975; Marino Research, Inc. 1986). A principle component of the seasonal inshore dragger fishery in Cape Cod Bay, Winter flounder are also angled in great numbers by recreational fishermon. Indood, analysis of creol survey data collected from recreational anglers at the Pilgrim Station Shorefront revealed winter flounder to be one of the top three most sought-after specios (Lawton et al. 1987). In consideration of their dominance in commercial and recreational catches and the localized nature of the stock represented in the Pilgrim Station area, winter flounder was selected as a representative important species (RIS) by the U.S. Environmental Protection Agency and the Massachusetts Division of Water Pollution Control. Life Stages Impacted and Sampling Protocol For each life stage of the winter flounder we have identified aspects of plant operation that constituto potential sources of impact (Table 1). It should be noted, however, that measurement of 57 N
1 impact caused by the operation of Pilgrim Station can be confounded by impacts from a number of other sources. Bay wide environmental conditions such as water temperature can affect spawning, as well as the survival of eggs and larvae (Je f f ries and Johnson 1974; Buckley 1982; Buckley et al. 1990). Exploitation of the resource by commercial and recreational fishermen can greatly affect local stock size. The liational Marine richeries Service has reported a coast wide decline in overall abundance of winter flounder from 1981 to 1989, directly attributable to fishing pressure (11EFC 1989). Review of Entrainment and Impingement Effects Entrainment Winter flounder move into shoal water in bays and estuaries to spawn in winter and early spring (Bigelow and Schroeder 1953), preferring sand or silt-sand bottoms (Clayton et al.1978) . Unlike those of other local flatfishes, winter flounder eggs are demersal and adhesive, often clumping together on the bottom (Broder 1924). Klein-MacPhee (1990) reported finding eggs in association with filamentous diatoms. Pearcy (1962) has suggested that production of demersal eggs provides certain advantages for survival. Eggs that remain at or near the bottom are less susceptible to disturbance by tidal movement or damage from ice. Further, water near the bottom is generally better oxygenated and undergoes less I variation in salinity. Similar advantage is extended to the 8arvac which also tend to remain near the bottom. Crawford and carcy (1985) suggest that negatively buoyant larvae are able to take Sa I l I
l1 I advantage of the two-layered density current system typical of deeper estuarios, thereby allowing them to remain in the relative safety of the estuary longer than more buoyant larvao. Initially, winter flounder larvao are troo-swimming, gradually undergoing metamorphosis to the edult form (this is reached when the larvae are from 0.9 to 1.3 mm long). Buckley (1982) reports that juveniles remain in or near shallow natal waters for most of their I first two years, only moving in respteso to extremos of heat or cold. Due to their domersal nature, few winter flounder eggs have been ontrained at pilgrim Station. Similarly, in a review of studies conducted from 1975 to 1984, Marino Research, Inc. (1986) stated that "... meaningful survival rates could not be datormined from those studios duo to the small sample sizes obtained, particularly among the entrainment collections.". Of those eggs collected, however, they reported that "wintor flounder eggs do survivo entrainment at pilgrim Station and the porcentago that do so may be fairly high...". Wintor flounder larvac, while bonthically oriented, nonetholoss have boon collected during entrainment campling in somewhat greator abundance than the eggs. Stono and Webster (1975) reported that the larvao have been collected from March through July; Marino Roscarch, Inc. (unpublished uata) documented thiu pattern for collections made from 1975 through 1990. However, entrainment of wintor flounder larvao does not appear to poso much I 59 g I
l I l of a throat to overall abundance of the species in the Pilgrim Station area. In a study, Itzkowitz and Schubel (1983) reported on the toleranco of five-day old fish to thermal shock. They found that winter flounder larvae appear to be resistant to acute thermal shock, the degree of resistance being ago dependent (yolk-sac larvao were found to be more tolerant than post yolk-sac larvao). Additionally, modeling by Stone and Webster (1975) to simulato impact over the expected 40-year operational period of the plant predicted a reduction in local population size of only 0.65%: modeling studios by Marino Research, Inc. (1986) woro in agreement with this magnitude of chango. Imoincoment Wintor flounder have a well documented affinity for sheltored estuaries and embayments (Bigolow and Schroeder 1953 Pearcy 1962) . Using data from trawl and seine studios conducted in tho area around pilgrim Station, Lawton et al. (1990) documented the Intake embayment to be a haven for small wintor flounder. Such behavior would scom to predispose the flounder to impingement on the intake screens at Pilgrim Station, and indood, Anderson (1990) reports winter flounder to be one of the more commonly impinged fish. However, it should be noted that while winter flounder ranked sixth in annual impingement collections from 1980 to 1989, the total I number of fish actually sampled during that period was 260. From their 40-year predictive model, Stono and Webster (1975) ostimated impingement would cause a 5.8% reduction in local population size. 60 1
I Reconfiguring the model to combino predicteo impingeluont and entrainment mortality for the same period yiolded a population reduction of 5.9%. Clearly, impingement presents a greater hazard to local wintor flounder abundance than entrainment of their eggs and larvae. But, given the low number of fish affected to dato, it would scom that natural variation and fishing pressure may have a greator impact on the local population than entrainment and impingement. Dischargo, Intako , and Sportfishing Related Effects Dischargo Thermal / Current Under normal conditions, Wintor f) under are able to tolerate water temperatures ranging from O' t c, 25' C (Pearcy 1962). Mortalities have boon reported for periods when ambient water temperature excooded one end or the other of the rango (Nichols 1918; Bigelow and Schroodor 1953). The throat of thermal shock caused by the dischargo of cooling water by pilgrim Station does not appear to be great due primarily to the mobility and bonthic nature of the species (Stone and Webster (1975). The plume of heated water created by the dischargo rapidly lifts from the bottom once clear of the dischargo canal, greatly reducing the potential for impact on the bottom-dwolling flounder. Further, any increase in the level of plant operation and resulting thermal effluent generally occurs gradually, allowing the flounder time to acclimate or move. Project dive records (unpublished data) revoal that wintor flounder are not often sighted in the immediato area of the discharge canal. Additionally, graphing plant output versus winter 61 I
I flounder catch / tow data from the project trawl study (Figure 13) revealed no relationship between plant operation and flounder catch in the area of the discharge. Intake: Thermal Backwashes As previously noted, vinter flounder are able to adapt to gradual changes in ambient water temperature, although sudden changes can cause localized mortality. A potential source of such impact in the intake embayment exists with the practice of thermal backwashes. During this procedure, heated water is to ucisc4icurtaiow ntacest ansu4t uoc 100 diverted to the intake rather E so E than being sent to this [ . discharge. This aids in
.g .
40 praventing a build-up of blue ' if k i f Emy - ro
} ,,,f,, ,ff a mussels in the primary o ,, ,h ,, ,,, ,, , ,, ,. ,, o circulatory water system. The YEAR g
, 3 sudden release of heated water Figure 13. Mean annual catch per tow of inte the intake embayment.could Pilgrim station for 1982 1990-winter flounder and annual % MDC operational level at k M
expose winter flounder in the area to thermal shock. However, in the absence of any evidence, to date, of flounder mortality in the intake, we conclude that backwashing has not presented a significant threat to the juveniles and adults found there. As regards the eggs and larvae, no I estimates have been made of the magnitude of impact from backwashing. I e g I.
I Soortfishing Winter flounder was the third most sought-after species in the I area of the plant (Lawton et al. 1987). This species is easy to catch and is a good food fish. In this regard, a potential impact at Pilgrim Station could result from increased fishing pressure, brought on by the accessibility provided by construction of the Shorefront area. Open from April through November, weather permitting, the Shorefront allows access to the discharge jetties, outer intake breakwater, and the beaches located adjacent to the discharge canal and at the head of the intake embayment. Despite the access, however, winter flounder has not ranked near the top in number of fish caught during sportfish surveys. Although flounc'.er are popular with fishermen, far more effort worst into the pursuit of striped bass and bluefish. As such, we do not believe that increased fishing mortality as a result of the opening of the Shorefront has negatively impacted flounder abundance in the Pilgrim area. I 7. Pollock
Background:
Basis for Selection Pollock are an active cool-water fish found on both sides of the Atlantic; their range in North American waters extends from the Gulf of St Lawrence to North Carolina. Eigelow and Schroeder (1953) reported their conter of abundance to be the Guif of Maine, where they occur both inshore (bays and estuaries) and on offshore 63 g I m -
I banks, pollock display strong schooling behavior, with schools being segregated by size (Steele 1963). Juveniles (" harbor pollock") move inshore in April (Steele 1963), having spent the winter in deeper waters. They remain in the shallow sublittoral zone until June, when they move to deeper inshore waters to avoid rising water temperature. Returning to the shallows in autumn, they again move out to deeper water in winter. Larger fish tend to stay in deeper water, both inshore and on off-shore banks, their movement governed chiefly by the abundance of food (Bigelow and Schroeder 1953) . Pollock are voracious feeders, preying chiefly on small fish and pelagic crustaceans. When feeding, pollock will move freely from the surface to depths of 200 meters. In the Gulf of . Maine, pollock have even been observed to break the surface In the pursuit of prey (Bigelow and Schroeder 1953). Exhibiting a marked preference for cool water, pollock have an upper thermal tolerance of 28' C (de Sylva 1969); however, they are rarely found at temperatures in excess of about 15.7' C. At the other extreme, adult pollock can tolerate a temperature of l' C I (Mironova 1961), although a water temperature of at least S' C is required for adequate incubation of its eggs (Bigelow and Schroeder 1953). Fished commercially by otter trawl and gill net, pollock were traditionally regarded as by-catch in local waters. However, in the absence of more desirable species such as cod and haddock, pollock have become the target of increased effort. Pollock are also popular as a recreational species, being aggressive, active fighters. Larger pollock are fished with bottom tackle as with 64 l I_
I cod, but the smaller " harbor pollock" can be taken on light spinning tackle.
- Pilgrim Station, pollock has been the most commonly occurring species in our gill not sets made at Rocky Point. Large schools of pollock have also been observed near Pilgrim's thermal plume by project divers, although such sightings have been sporadic. Analysis of creel survey data collected from recreational anglers at the Pilgrim Station Shorefront revealed pollock to be one of the more commonly caught species (Lawton et al. 1987).
Considering their commercial and recreational importance, dominance in Division gill not catches, and the potential for mortality due to entrainment and impingement at Pilgrim Station, pollock was selected as a representative important species (RIS) by the U.S. Environmental Protection Agency and the Massachusetts Division of Water Pollution Control. Life Stages Impacted and Sampling Protocol For each life stage of the pollock, we have identified aspects of plant operation that constitute potential sources of impact (Table 1). As with other exploited species, however, measurement of impact caused by the operation of Pilgrim Station can be masked by impact. from fishing, as well as from other environmental actions. The National Marine Fisheries Service (NMFS) has documented a marked decline in coast wide pollock stocks since the mid-1980's, and a further decline is expected (NEFC 1989). Due to over-fishing and poor recruitment, they characterize the stock as I "
I being over-exploited. In addition, local movement of pollock schools, and hence local abundance, can be affected by ambient water temperature as well as the abundance of prey species (Bigelow and Schroeder 1953; Steele 1963). Review of Entrainment and Impingement Effects Entrainment Pollock spawn in autumn and early winter, beginning once water temperatures decline to 8-9' C. Spawning increases as temperatures fall to 6' C but then decreases as temperatures decline further to 2' C (Clayton et al. 1978). Their eggs are buoyant, and incubation requires 9 days at a temperature of 6* C and 6 days at 9' C. The larvae remain near the water's surface for at least 3 months after hatching (Eigelow and Schroeder 1953). Given the planktonic nature of pollock eggs and larvae, the potential exists for impact from power plant entrainment. Examination of entrainment sampling data at Pilgrim Station (Marine Research, Inc. - unrublished data) reveals that pollock larvae and, to a lesser extent, their eggs have been entrained at Pilgrim Station but never in abundance. Assuming 90% mortality of entrained eggs and larvae, a model prepared by Stone and Webster (1975) predicted the annual loss of 4 to 316 adult pollock due to entrainment. In view of these findings, we do not believe that entrainment has had a significant impact on pollock abundance. I Imoincement Pollock, especially the smaller " harbor pollock", are common inhabitants of the inshore waters around Pilgrim Station, which I 66 1 I_
I
~
places them at risk from impingement on the intake screens. However, pollock are strong active swimmers, remaining in an area I only as long as there is an abundance of prey. Such behavior lessons the risk of impingement, and in fact, very few pollock have been impinged at Pilgrim Station since the inception of operation. No pollock were impinged in 1989 (Anderson 1990). In a comparison of plant induced mortality with that from commercial fishing, Stone and Webster (1975) concluded that Pilgrim Station would cause substantially less than 1% of the mortality caused by commercial fishing. Such impact would, therefore, be considered negligible, Discharge, Intake , and Sportfishing Related Effects Rischarae: Thermal / Current Project dive records (unpublished data) reveal that pollock are common, though sporadic visitors to the area of the discharge canal. On occasion, schools of 100+ individuals have been sighted moving through the " control zone"; whereas on other dives, no pollock have been sighted. In 1990, no pollock were sighted urAu carca ren citt wer ser practur Anuvat uoc during the entire observational 5
, l _.
study (Volume 1 - this report). too 3 L . j . ,, Examination of our gill net data )/ '
- s '
[ - ,, from sets made at Rocky Point 5 5 c [ ! I " z , so reveals pollock to be ranked o
, , , , , , , , , , , , , ,,{; , o YEMI
!- first in overall catch. However, a graphic analysis Figure 14. Mean annual 5 panel gitt net catch l I of potlock and annual % MDC opermtional level at (Figure 14) of project gill net pilgrim station for 1973 1990. 67 lI l
I data suggests there is no relationship between plant operation and pollock catch in the area of the discharge. When the data were tested for correlation, no relationship (r = 0.225; P > 0.05) was found between Pilgrim Station operational output and catch per unit effort (Lawton et al. 1990). Fluctuations in local abundance are more likely the result of natural variation, and, as documented by NMFS (NEFC 1989), fishing mortality. Intake: Thermal Backwashes Given the mobility of adult pollock and the low numbers of eggs, larvae, and juveniles collected by entrainment and impingement, it seems unlikely that thermal backwashing into the intake embayment at Pilgrim Station would impact this species. Soortfishina Pollock comprised 9% of the overall sportfish catch recorded during creel surveys at the Pilgrim Station Shorefront (Lawton et al. 1987). Most were caught by anglers bottom fishing from off the outer intake breakwater. As was noted for commercial catches, pollock was generally not a species of preference, but instead was sought in the absence of striped bass, bluefish, or mackerel. In view of the moderate catches and low level of effort directed at this species, we do nct believe that increased fishing mortality as a result of the opening of the Shorefront to anglers has impacted pollock abundance in the Pilgrim area. I. I
'8 I< l E_
IV. IMPACT PERSPECTIVE We selected eight species to assess Pilgrim Station impact. The American lobster and the winter flounder are abundant benthic residents in the Pilgrim area and support important commercial and recreational fisheries. The bluefish and striped bass have been seasonally abundant off the power plant and are highly prized game fish that are avidly sought by sport fishermen in the discharge area. The pelagic schooling Atlantic menhaden is commercially harvested in Massachusetts Bay by purse seiners and has been l involved in two major incidents of gas bubble disease in the discharge area at Pilgrim Station. The Atlantic silverside is the most abundant finfish in the Pilgrim area and is an important link in the food chain. An endemic groundfish, cunner resides in the intake embayment and in the immediate vicinity of the breakwaters and discharge jetties at Pilgrim Station for a good part of the l year. The pollock is a dominant benthi-pelagic species that has led gill net catches off Pilgrim Station and has been caught by sport fishermen in the area. Monitoring data collected to date off the power station reveal there have been biotic changes and abiotic environmental disruptions; however, these have been localized or occasional in occurrence. Because Pilgrim Station has operated overall at an average of 46.8% of its capacity, we most likely have not experienced plant impact to its fullest. Assessment of impact at this level of plant output may not be valid for an extended period of higher operational level. 69
I I V.. CONCLUSIONS cunner
- 1. Cunner has been among the five dominant finfish species I
impinged at Pilgrim Station over the years of station operation. As many as 1,600 cunner have been impinged at Pilgrim Station in a year (1980).
- 2. This species most likely spawns in the immediate vicinity of I
the power plant, and their pelagic oggs and larvae are subject to entrainment. In fact, the Labridae-Limanda groups have dominated entrainment collections of fish eggs at Pilgrim Station, comprising over 90% of the total.
- 3. Based on temperature tolerance data, there is likely and exclusion area to cunner in the discharge canal and the near thermal plume area during late summer.
- 4. The size of the cunner population in the Pilgrim area appears I
to have been substantially down since 1985, however, there is
-evidence of a strong local year-class being produced in 1990.
I S. Analyses of our gill net data and diving observations indicate. that cunner (age 1+ and older) are attracted to the thermal discharge current at Pilgrim Station. l s
I
- 6. The intake embayment is an ideal nursery area for young-of-the-year cunner providing cover / structure and food. From our i.
! haul seine sampling in 1990, we found that juvenile cunner (2-3 cm TL) abounded in the intake, where 68% of all the cunner were seined. I
- 7. Cunner has led the overall sportfish catch at Pilgrim Shorefront. Sportfishing mortality can be extensive, e.g. , in 1985, an estimated 3,500 cunner were caught by anglers fishing primarily from the breakwater.
I l American Lobster i 1. Entrainment of lobster larvae has been negligible at Pilgrim Station, while only small numbers of juveniles have been impinged on the intake screens. The percentage of culls in the surveillance area in 1990 was 2. significantly lower than in the reference area, but the difference does not appear to be power-plant related.
- 3. Analysis of commercial lobster pot catch data indicate there are no significant differences in catch rates between the surveillance and reference areas.
l
.I..
E 71 3 g
I l
- 4. When testing for a relationship between commercial legal 5 lobster catch rate and a measure of plant operation at Pilgrim Station (MDC Net %), we have conflicting findings. With data from 1973-1983 using a parametric correlation test, a significant negative correlation (P = 0.05) was found between the variables. However, when we included data from 1985 and 1990 (high operational years) to the data base and retested for association, we did not find a statistically significant correlation. This may have resulted from the placement of commercial gear sampled in the discharge area. We have no control over positioning of the commercial gear spatially which can be deployed far enough away from the discharge canal that the thermal current is probably not a major factor affecting lobster distrjbution.
- 5. Data from our June through September 1990 research lobster pot study were the first collected from a relatively high operational year, but in July and September there were reductions in heat output to 50% and 22%, respectively. We found no measurable impact of Pilgrim Station on the legal lobster catch rate at the discharge in the summer of 1990.
- 6. Analyses of experimental sublegal catch data collected in 1990 indicated that Stations G and F had significantly lower sublegal catch rates than the other two discharge stations from July-September. As these stations (especially G) are
>2 I
proximal to the discharge canal, we hypothesized that the speed of the discharge current at these sites impacted sublegal catches by reducing their mobility and thus reducing their abundance there.
- 7. A near significant (P = 0.06) association between sublegal catch rate and Pilgrim Station MDC was noted at Station G in 1990 using the nonparametric Kendall's coefficient of rank average correlation, despite a reduction in plant MDC to 50%
in July and 22% in September. Bluefish and Striced Bass
- 1. Impingement and entrainment do not impact striped bacs and bluefish at Pilgrim Station.
- 2. There is most likely an attraction of both species to the warm water of the thermal plume in the spring and late fall.
Conversely, an exclusion zone likely occurs in August because of-high temperatures.
- 3. Bluefish and striped bass are attracted to the discharge current at Pilgrim Station as a feeding ground. Their numbers generally are low in the Pilgrim area when the plant is not operating or only discharging a water current of low velocity.
73
I
- 4. The mean gill net catch rates of bluefish and striped bass for 1983,1985, and 1990 (years of high Pilgrim Station output) were 45% and 88% higher, respectively, than the grand means for 1984, 1986-1989 (outage or low output years).
- 5. Our diving survey has revealed that in over 10 years of observations of striped bass and bluefish sighted of f Pilgrim Station, 97% of the bass and 85% of the bluefish were observed in the path of the discharge current. No bluefish and only 11 bass were sighted by divers in 1984 and from 1986 through 1988 (outage years), but in 1983, 1985, and 1989-1990 (operational years), numbers of each species were seen in the thermal plume.
- 6. The sportfish catches of both species at Pilgrim Station have I
been strongly tied to station operation. An estimated 1,000 bluefish and 150+ striped bass were taken by shore-based _ anglers in 1983 at Pilgrim Shorefront and 2,200 bluefish and almost 400. bass in 1985, years of high plant output (> 80% _. thermal capacity and 2 circulating seawater pumps operating). Conversely, with the absence of waste heat and a marked reduction in flow of water out the discharge canal during the
.. summe r and fall seasons of 1984 and 1986-1988 (outage periods), the sportfish catches of 'both species markedly declined to about 150 fish in total for all four fishing seasons. During the attenuated July - August creel survey of I
I 1989 (transitional year), the catch of bluefish showed a slight upswing (68 bluefish reported). During the May - August survey in 1990 (operational year), the catches of bluefish and bass rose to 312 and 150, respectively.
- 7. The attraction of these game fish to the thermal discharge current, concentrating them for extended periods of time at a point source near shore, has a negative side to it, however.
This increases the potential for stress via heat or cold shock, gas supersaturation, and sizably adds to sportfishing mortality. Atlantic Silverside
- 1. The Atlantic silverside is the most abundant fish in the Pilgrim area.
- 2. Silverside eggs are not entrained at Pilgrim Station, while their larvae have a very low incidence of entrainment.
- 3. The Atlantic silverside is the dominant species impinged at Pilgrim Station. Impingement has been projected to be as high as 87,750 silversideo (1981). There are large numbers seined in the intake each year.
I. I 75
.I {
l I
l I
- 4. Based on thermal tolerance data, there is probably a 4.45 ha exclusion area to silversides off the discharge canal in mid-to late summer.
- 5. The effects of the thermal plume are most likely minimal to I
the Atlantic silverside population because af their great abundance in the Pilgrim area, and generally their ability to move out of the discharge area to avoid stressful temperatures. Atlantic menhaden
- 1. The entrainment of menhaden eggs through Pilgrim Station has been relatively low, while menhaden larval entrainment has been rare.
I
- 2. Impingement of menhaden (mostly juveniles) has been relatively light over the years at Pilgrim Station.
- 3. Stone and Webster (1975) estimated that losses to the menhaden population via entrainment and impingement at Pilgrim Station were negligible.
I
- 4. Annual gill net catch data of adult menhaden from -1971-1990 show depressed catch rates since 1980. There is no apparent I
~
I E_ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - - - - - - _ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~ - - - - - - - - - ' ' - ^ - - ^ - - - - - - - ~ ~ - - - - - - - - - ' - " - ^ - - - ----
l I relationship between plant operational status and annual mean menhaden gill net catch.
- 5. Menhaden have shown an attraction to thermal plume temperatures at Pilgrim Station in the spring. Substantial mortalities of adult menhaden in the Pilgrim discharge canal have occurred in April of 1973 and 1975 as a result of gas bubble disease. In August 1975, about 3,000 menhaden died in the discharge area because of thermal stress. In August 1985, an estimated 300 juvenile menhaden were afflicted with gas bubble disease in the discharge canal.
I 6. Stock-recruitment modeling of menhaden, incorporating the gas bubble disease mortalities at Pilgrim Station, revealed a negligible impact on the overall menhaden population (Stone and Webster 1975). I Winter Flounder I 1. Because winter flounder eggs are demersal, few have been entrained at Pilgrim Station. The entrainment of their larvae does not appear to pose much of a threat to overall stock abundance. I 2. The intake embayment - has been a haven for small juvenile winter flounder. I " l 1 I
1
- 3. Winter flounder ranked sixth in annual impingement collections from 1980-1989 at Pilgrim Station. From modeling, Stone and Webster (1975) predicted that impingement at Pilgrim Station would bring about a 5.8% reduction in size of the local population of winter flounder.
I
- 4. Project diving records reveal that winter flounder are not often sighted in the immediate area of the discharge canal.
- 5. We found no relationship between trawl cEtch of winter I
flounder in the outer periphery of the near-tield area of the discharge and plant operation. Pollos$
- 1. Pollock eggs and larvae are not entrained in numbers at Pilgrim Station. It is believed that entrainment has not had a significant impact on pollock abundance.
- 2. Pollock are rarely impinged on the intake screens at Pilgrim I
Station. After comparing impingement mortality with commercial fishing mortality, Stone and Webster (1975) concluded that impingement was substantially less than 1% of I' that caused by commercial fishing. Such a station impact would, therefore, be negligible. I
'a I
I
- 3. Sighted sporadically in the discharge area by project divers, pollock, nevertheless, ranked first in gill not c&tches.
r However, no relationship (r = 0.225; P>0.05) was found between l Pilgrim Station operational output and gill net catch per unit effort. Fluctuations in local abundance are believed to result from natural variation.
- 4. Pollock comprised 9% of the overall sportfish catch recorded during creel surveys conducted at Pilgrim Station Shorefront.
In view of the moderate catches and low level of directed effort, recreational fishing is believed not to markedly impact pollock abundance in the Pilgrim area. I I I I I i
>e
I l VI. ACKNOWLEDGEMENTS I The authors acknowledge the contributions of Hell Churchill, Steve cadrin, and Paul Caruso, staff members of the Division, who assisted in diving operations. We thank Chris Kyranos for allowing us to sample his commercial lobster catch, and Raymond Dand and Robert Ellenberger for collecting creel data at the Pilgrim Shorefront. A special thanks to the Division's Kim Trotto and Marie Callahan for word-processing various sections of this report, and to Steve Cadrin for statistical consultation. Finally, we appreciate the role of Robert D. Anderson of Boston Edison Company, W. Leigh Bridges of the Division, and the Pilgrim Administrative-Technical Committee for their input on study programs and editorial comments on project reports. I I I I I I I I I_
I I VI. LITERATURE CITED I Anderson, R.D. 1990. Impingement of organisms at Pilgrim Nuclear Power Station. ID: Marine Ecology Studies Related to I Operation of Pilgrim Station, Semi-annual Report No. 35. Boston Edison Company, Braintree, MA. Atlantic States Marine Fisheries Commission. 1979. Atlantic I menhaden - a most abundant fish. Atlantic Coast, Leaflet No. 2. Marine Resources of the I Ambrose, N.S. J. 1870. On fishes of St. Margaret's Bay. Trans. Proc. Inst. Nat. Science, Halifax Vol. II., Part 2. I Auster, P.J. 1985. Homams americanus, Factors affecting catch of American lobster, in baited traps. NOAA National Undersea Research, University of Connecticut, Groton, CT 46 pp. Austin, H.M. , A. D. Sosnow and C. R. Hickey, Jr.1975. The eMects of temperature on the development and survival of the eggs and larvae of the Atlantic silverside, Atenidia menidia. Trans. An.sr. Fish. Soc. 104(4): 762-765. Bigelow, H.B., and W. C. Schroeder. 1953. Fishes of the Gulf of I Maine. U.S. Fish and Wildlife Service Fishery Bulletin 53: 577 PP. BMDP Statistical Software, Inc. 1990. BMDP Statistical Software I Manual Volume 1. 625 pp. Breder, C.M., Jr. 1924. Some embryonic and larval stages of the winter flounder. Bull. U.S. Bur. Fish, 38:311-315. Buckley, L.J. 1982. Effects of temperature on growth and biochemical composition of larval winter flounder, Psuedopleuronectes I' americanus . Mar. Ecol. Prog. Ser. 8:181-186. Buckley, L.J . , A.S. Smigielski, T.A. Halavik, and G.C. Laurence. 1990. Effects of water temperature on size and biochemical composition of winter flounder Psuedoplcuronectes americanus at hatching and feeding initiation. Fish. Bull. 88:419-428. Cadigan, K.M., and P.E. Fell. 1985. Reproduction, growth and feeding habits of Atenidia menidia in a tidal marsh - estuarine system in southern New England. Copeia 1985(1): 21-26. Campbell, A. 1983. Growth of tagged lobsters (Homarus americanus) off I Port Maitland, Nova Scotia, 1948-1980. Can. Tech. Rep. Fish. Aquat. Sci. No. 1232. 10 pp. 81 i
l I l 1 I Clayton, G., C. Cole, S. Murawski, and J. Parrish. 1978. Common 3 Marine Fishes of Coastal Massachusetts. Dept. of Forestry and E Wildlife Management. Massachusetts Cooperative Fishery Research Unit. 231 p. Conover, D.O. , and M.R. Ross.1982. Patterns in seasonal abundance, growth and biomass of the Atlantic silverside Atenidia menidia, in a New England estuary. Estuaries 5(4): 275-286. Conover, D.O., and S.A. Murawski, 1982. Offshore winter migration of the Atlantic silverside, Alenidia menidia. Fish. Bull. 80 (1) : 145-150. Conover, D.O., and B.E. Kynard. 1984. Field and laboratory observations of spawning periodicity and behavior of a northern population of the Atlantic silverside, Atenidia menidia a g (Pisces: Atherinidae). Envir. Biol of Fish. 11(3): 161-171. Conover, D.O. 1985. Field and laboratory assessment of patterns in fecundity of a multiple spawning fish: the Atlantic silverside Atenidia menidia. Fish. Bull. 83(3): 331-341. Conover, D.O., and M. H. Fleisher. 1986. Temperature - sensitive period of sex determination in the Atlantic silverside, Atenidia menidia. Can J. Fish. Aquat. Sci. 43: 514-520. Crawford, R.E. and C.G. Carey. 1985. Retention of winter flounder larvae within a Rhode Island salt pond. Estuaries 8 (2B) : 217-227. de Sylva, D.P. 1969. Theoretical considerations of the effects of g heated effluents on marine fishes. In: Biological Aspects of 5 Thermal Pollution, P.A. Krenkel and F.L. Parker (eds). Proceedings of the National Symposium on Thermal Pollution. 3 Portland, Oregon, June 1968. Vanderbilt University Press. pp. 229-243. g-Estrella, B.T.1985. Massachusetts coastal commercial trap sampling program May-November 1984. Commonwealth of Massachusetts Dept. Fisheries, Wildlife, and Environmental Law Enforcement. Division Marine Fisheries, Boston, MA. 58 pp. Estrella, B.T., anc D.J. McKiernan. 1986. Massachusetts coastal commercial trap sampling program May-November 1985. Commonwealth of Massachusetts Dept. Fisheries, Wildlife, and Environmental Law Enforcement. Division Marine Fisheries, Boston, MA. 74 pp. I 82 I 1 gI
. ~-- - - - -
I Green, J.M., and M. Farwell. 1971. Winter habite of the cunner, Tautogolabms adspersus (Walbaum 1792), in Newfoundland. Can. J. Zool. 49: 1497-1499. I Grosslein, M.D.1969. Groundfish survey program of BCF Woods Hole. Commer. Fish. Rev. 31(8-9): 22-30. Hoff, J.G., and J.R. Westman. 1966. The temperature tolerances of three species of marine fishes. J. Mar. Res. 24(2): 131-140. Howe, A.B. and P.G. Coatos. 1975. Winter flounder movements, growth, and mortality off Massachusetts. Trans. Amer. Fish, i Soc. 104:13-29. Itzkowitz, N. and J.R. Schubel. 1983. Tolerance of five-day old I winter flounder, Psurdopleuronectes amencanus, larvae to thermal shock. Fish. Bull. 82 (1): 913-916. I Jeffries, H.P. and W.C. Johnson, 1974. Seasonal distributions of bottom fishes in the Narragansett Bay area: seven-year variations in the abundance of winter flo'inder (Psuedopleuronectcs amedcanus) . J. Fish. Res. Brd. Can. 31: 1057-1066. Jensen, A.C. 1970, Thermal pollution in the marine environment. The Conservationist. State of New York, Dept. of Conservation Oct.-Nov.: 8-13. Johansen, F.1925. Natural history of the cunner (Tautoplabms adtpersus Walbaum). Contr. Can. Biol. 2(17): 442-467. Keser, M., D.F. Landers , Jr. , and J . D. Morris. 1983. Population characteristics of the American lobster, Homams amencanus, in eastern Long Island Sound, Connecticut. NOAA Tech. Rep. NMFS SSRF-770. I Kinne, O., Ed. 1969. Marine Ecology, Treatise on Life in Oceans and Coastal Waters". Interscience, London. 681 pp.
"A Comprehensive Integrated Wily-Klein-MacPhee, G. 1978. Synopsis of biological data for the winter flounder, Psuedoplcuronceresamedcanus (Walbaum) . NOAA Technical Report NMFS Circular 414. FAO Fisheries Synopsis No. 117.
I Lawton, R.P., C. Sheehan, T. Currier, P. Brady, M. Borgatti, V. Malkoski, and S. Correia.1986. Final report on dissolved gas I saturations in the inshore marine waters of Cape Cod Bay and incidents of gas bubble disease at Pilgrim Nuclear Power Station 1973-1985. Pilgrin Nuclear Power Station Marine I Environmental Program Report Serie.s No. 1, Boston Edison Company. 33 pp. 83 I
l l Lawton, R.P., R.D. Anderson, P. Brady, C. Sheehan, W. Sides, E. I Kouloheras, M. Borgatti, and V. Malkoski. 1984. Fishes of 3 western inshore Cape Cod Bay: studies in the vicinity of the Rocky Point shoreline, p. 191-230. In: J. D. Davis and D. 3 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. l 1985. Annual report on monitoring to assess impact of Pilgrim W Nuclear Power Station on marine fishery resources of western Cape Cod Bay. Project Report No. 38 (Jan.-Dec. 1984). 1D: 3 Marine Ecology Studies Related to Operation of Pilgrim g Station, Semi-annual Report No. 25. Boston Edison Company, Braintree, MA. Lawton, R.P., V. Malkoski, S. Correia, B. Kelly, C. Sheehan, M. Borgatti, and P. Brady. 1987. Final report on marine recreational fishing at the Pilgrim Station shorefront: 1973- g 1975, 1983-1986. Pilgrim Nuclear Power Station Marine 3 Environmental Program Report Series No. 3. Boston Edison Company. 53 pp. Lawton, R.P., B.C. Kelly, V.J. Malkoski, M.R. Borgatti, and J.F. Battaglia. 1990. Annual report on monitoring to assess impact of Pilgrim Nuclear Power Station on marine fishery resources of western Cape Cod Bay (Vol II) . Project Report No. 48 (Jan.- Dec. 1989). Jn: Marine Ecology Studies Related to Operation of Pilgrim Station, Semi-annual Report No. 35. Boston Edison Company, Braintree, MA. Lund, W.A., Jr., and G.C. Maltezos. 1970. Movements and a migrations of the bluefish (Pomatomus saltardx) tagged in waters g of New York and southern New England. Trans. Amer. Fish. Soc. 4: 719-725. Lyman, H. 197 4 . Successful Bluefishing. International Marine Publishing Company. Camden, Maine. 112 p. Lux, F.E. , A.E. Peterson, Jr. , and R.F. Hutton.1970. Geographical variation in fin ray number in winter flounder, Psuedopleumnceres amedcanus (Walbaum) , of f Massachusetts. Trans. Amer. Fish. Soc. 99:483-488. Marine Research, Inc.1990. Ichthyoplankton entrainment monitoring at Pilgrim Nuclear Power Station, Jan.-Dec.1989 (Vol 2). In: Marine Ecology Studies Related to Operation of Pilgrim Station. Final Report. Boston Edison Company. I I
~ . . _
I Marine Research, Inc. 1986. Winter flounder early life history studies related to operation of Pilgrim Station - A review 1975-1984. Pilgrim Nuclear Power Station Marine Environmental Monitoring Program Report Series No. 2. Boston Edison Company, Braintree, MA. Massachusetts Division of Marine Fisheries.1977. Summarization of Massachusetts marine sportfishing statistics, 1975. 100 I. Cambridge St., Boston, MA. 42 pp. McCracken, F.D.. 1963. Seasonal movements of the winter flounder, I Psuedopicuroncercs americanus (Walbaum) on the Atlantic coast. J. Fish. Res. Brd. Can. 20:551-586. McLeese, D.W. 1956. The effects of temperature, salinity, and oxygen on the survival of the American lobster. J. Fish. Res. Brd. Can. 13: 247-272. Middaugh, D.P., R.G. Domey and G.I. Scott. 1984. Reproductive rhythmicity of the Atlantic silverside. Trans. Amer. Fish. Soc. 113: 472-478. I Miller, R.J. 1983. Considerations for conducting field experiments with baited traps. Fisheries 8(5): 14-17. Miller, R.J. 1990. Effectiveness of crab and lobster traps. Can. J. Fish. Aquat. Sci. 47: 1228-1251. Mironova, N.J. 1961. Biology of the Barents Sea saithe, Pollachius sens (L.). Int. Reve. ges. Hydrobiol. 46(3):47-459. Nichols, J.T.1918. An abnormal winter flounder and others. Copeia 55:37-39. I Nicholson, W.R. 1978. Movements and population structure of Atlantic menhaden indicated by tag returns. Estuaries 1(3): 141-150. Northeast Fisheries Center, 1989. Status of the Fisheries Resources off the Northeastern United States for 1989. National Marine Fisheries Service, Woods Hole, MA. 110 pp. Olla, 8.L., and A.L. Studholme.1971. The ef fect of temperature on the activity of bluefish, romatomus saltatdr L. Biol. Bull. 141:
=
337-349. I I 88 l l
I l Olla, B. L., A. J. Bejda, and A. D. Martin. 1975. Activity, movements, and feeding behavior of the cunner, Tauuplabrus o&persus, and comparison of food habits with young tautog, g Tautogo onitis, of f Long Island, New York. Fish. Bull. 73 (4) : 895- 3 900. Pearcy, W.G. 1962. Ecology of an estuarine population of winter flounder Psurdoplcuronectes arncricanus (Walbaum). Bull. Bingham. Oceanogr. Collect., Yale Univ. 18(1), 78 p. Perlmutter, A. 1947. The blackba a flounder and its fishery in New England and New York. Bull. Bingham. Oceanogr. Collect. , Yale Univ. 11(2), 92 p. Pierce, D.E., and A.B. Howe. 1977. A further study on winter flounder group identification of f Massachusetts. Trans. Amer, a Fish. Soc. 106:131-139. g Phillips, J.H. 1990. Rockfish - they're back. Maryland Department of Natural Resources. Annapolis, Maryland. 23 pp. Scherer, M.D. 1984. The ichthyoplankton of Cape Cod Bay, p. 151-190. In: J.D. Davis and D. Morriman (editors) , Observations on the Ecology and Biology of Western Cape Cod Bay, Massachusetts. Springer-Verlag, Berlin, FRG. 289 pp. Smith, W.G., and A. Wells. 1977. Biological and fisheries data on striped bass, Morone satatilis (Walbaum). Sandy Hook Laboratory, National Marine Fisheries Survice, Highlands, NJ 42 pp. Sokal, R.R., and F. J. Rohlf. 1969. Biometry: The principles and practice of sta'cistics in biological rr. search. W. H. Freeman and Company, San Francisco. 776 p. : Steele, D.N. 1963. Pollock (Pollachius vitens) in the Bay of Fundy. J. Fish. Res. Brd. Can. 20:1267 '.314. Stone and Webster Engineering Corporation. 1975. 316 (a and b) demonstration for Pilgrim Nuclear Power Station - Units 1 and I
- 2. Boston, Massachusetts.
Stone and Webster Engineering Corporation. 1977. Supplemental Assessment in support of the 316 Demonstration dor Pilgrim g Nuclear Power Station - Units 1 and 2. Boston, Massachusetts, g Thomas, J.M., and P. Van Voris, 1986. Statistical approaches for quantitatively assessing ecological impact and risks. Proceedings: Risk Assessment in Aquatic Ecology, pp 2-63 to 2-81, 3L 86 a
I Walters, K. 1987. Stripers: good news and bad. Salt Water Sportsman 48(1): 71-73. I Wheatland, S.B. 1956. Pelagic fish eggs and larvae. Bull. Bingham. Oceangr. Coll., Yale Univ. 15 234-314. I Williams, G.C. 1967. Identification and seasonal size changes of eggs of the 1abrid fishes, Tauuptabrus adstesus and Tautoga onitis, of Long Island Sound. Copeia 1967 (2): 452-453. Williams, S.J., T.P. Smith, H. Speir, and S. Early. 1983. Maryland Saltwater Sport Fishing Survey - 1980. Maryland Dept. of Natural Resources-Tidewater Administration. 124 pp. Woolner, F., and H. Lyman. 1983. Striped Bass Fishing. Nick Lyon Books, Winchester Press. 192 p. Young, J.S. 1974. Menhaden and power plants - a growing concern. Mar. Fish. Rev. 36(10) October, 1974. I I I I e I I I I I I I "' I
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, I 11NAL SEMI-ANNU AL REPORT Number 37 I (Volume 1 of 2) on I I BENTillC ALGAL AND FAUNAL MONrrORING AT TIIB PILGRIM NUCLEAR POWER STATION (CilARACTERIZATION OF BENTHIC COMMUNITIES) January-December 1990 I to BOSTON EDISON COMPANY Regulatory Affairs Department
.g Licensing Division 3 25 Braintree 11111 OfUce Park Braintree, Massachusetts 02184 I
g From SCIENCE APPLICATIONS INTERNATIONAL CORPORATION 89 Water Street Woods llole, MA 02543 (508) 5447882 I I 1 April 1991 I I
TAllLE OF CONTENTS L EXECUTI VE S U M M ARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....... .... I r l.0lNTRODUCrlON .................. ..................... ..... 4 2.0 M l?l'ilODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............. .. .. 4 2.1 FIELD S AMPLING . . . . . . . . . . . . . . . . . . . . . . ... .......... 4 2.2 LAllORATORY AN ALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l 2.3 D ATA AN ALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 9 3 .0 RES U LTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I 3.1 QUANTITATIVE FAUNAL MONII'ORING . . . . . ..................
. 13 13 3.1.1 Syr tematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3.1.2 Species Richness . . . . . . . . . . . ........ ... 13 1
3.1.3 Paunal Demity .......................... ......... 14 3.1.4 Species Dominance . . . . . . . . . . . . . . . . . . . . ........... , 17 l 3.1.5 Species Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 5 3.1.6 Community Analysis . . . . . ........... ............... 24 3.2 QUANTrrATIVE ALGAL MONrrORING . . . . . . . . . . .............. 32 l3 3.2.1 Systematics . . . . . . . . . . . . . . . . . . . . . . . . . . ..... ...... 32 l 3.2.2 Algal Community Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 3.2.3 Algal Community Overlap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 3.2. 4 Algal tliomau . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 1 3.3 QUALrrATIVE TRANSECT SURVEY . . . . . . . . . . . . . . . . . . . . . . . ... 40 3.3.1 April 1990 Tramect Survey ............................ 45 3.3.2 June 1990 Tramect Survey . . . . . . . . . . . . . . . . . . . . . . . . .... 45 1 3.3.3 Smtemlier 1990 Tramect Survey . . . . . . . . . . . . . . . . . . . . . . . . . 45 3.3.4 December 1990 Tramect Survey ....... ................. 46
4.0 CONCLUSION
S . . . . . . ....................................... 47 4.1 FAU N AL STU DIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 4.2 ALG A L STUDIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 4.3 QUALITATIVE TRANSECT SURVEYS . . . . . . . ................ 48 5.0 LTTEHATURE CITED ..,,............... ........, ............ 48 AP P E N D IX A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A1 1 I i
LIST OF FIGURES Figure 1. location of itenthic Sampling Sites near Pilgo n Station. ............... 5 r Figure 2. Suction Lift Device Used by Divers to Collect llenthic Samples. . . . . . . . . . . . 6 t Figure 3. Design of the Qualitative llenthic Trarueet Sampling Program at Pilgrim Station. ........................................... . B Figure 4. Density of llenthic Fauna in April arxl September 1990. . . . . . . . . . . . . . . . 16 l Figure 5. Iturlbert Rarefaction Curves for Total Fauna at the Emuent, Manomd Point, arxl Rocky Ibint Stations, September 1990. El*, Mi*, Rl*: Mytilus Ea c t ud ed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 lR Figure 6. Similarity Analysis liased on NESS arxl Group Average Sorting. A, April 1990; D. September 1990, Replicates Separate. . . . . ................ 25 Figure 7. Similarity Analysis with lirayfurtis and Group Average Sorting, April arx! I September 1990, Raplicates Pooled. . . . . . . ..................... 26 Figure 8. Inverse Cluster Analysis of the 50 Most Aburxiant Species, Spring and Fall 1 Combined, using liray-Curtis arxl Group Average Sorting. . . . . . . . . ..... 27 Figure 9. Corstancy Diagram for Species Groups and Station Groups in 1990. Clustering is with Dray-Curtis and Group Average Sorting. . . . . . . ...... 30 Figure 10. Fidelity Diagram for Species Groups arxl Station Groups in 1990. Clustering is with Dray-Curtis and Group Average Sorting. . . . . . . . . . . . . . . . . . . . . 3i Figure 11. Algal Community Overlap (Jaccard's Coemcient of Community) and Number of Species Shared lloween Replicate Pairs, April 1990: A, Manomet Point Station; II, Rocky Point Station; C, Effluent Station; D, Station Overlap. .... 34 Figure 12. Algal Community Overlap (Jaccard's Coefficient of Community) and Number of Species Sharal lidween Replicate Pairs, September 1990: A, Maromet Point Station; H, Rocky Point Station; C, Emuent Station; D, Station Ov erl ap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Figure 13. Stunted and Denuded Omdrus Zones Observed in April 1990. .......... 41 Figure 14 Stun'ed and Denuded OwMrus Zones Observed in June 1990. . . . . . . . . . . . 42 Figure 15. Stunted and Denuded OmMrus Zones Observed in September 1990. . . . . , , . 43 Figure 16. Stunted and Denuded Omdrus Zones Observed in December 1990. ....... 44 il
I LIST OF TAllLES Tsble 1. Algal Irxlicator Speeles used for Quantitative Community Analysis. . . . . . . . . 10 Table 2. Faunal Species Richness at the Emuent, Manc. met Point, arxl Rocky Point l Stations in April and September 1990. . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Table 3. Faunal Demities at the Emuent, Manomd Point, arxl Rocky Point Stations in April 1990. . . . . . . . . . . . . . . . . . . . . . . . . . . ............ ... 15 Table 4 Fificen Most Abundant Species at the Emuent Station in Apru arul September , Table 5. 1990................................. .............. Fifteen Most Aburxlant Species at the Manomet Point Station in April and 18 m' September 1990. . . . . . . . . . . . . . . . . . . . . . . . . . . . gl
............ 19 Table 6. Fifteen Most Abundant Species at the Rocky Point Station in April arv.!
September 1990. . . ............................ ........ 20 Table 7. Community Parammers for the Emuent, Manoma Point, and Rock Statiom in April 1990. . . . . . . . . . . . . . . . . . . . . . . . . .......... . .y Point 22 Table 8. Community Parameters for the Emuent, Manomet Point, and Rocky Point Statiom in September 1990. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Table 9. Species Groupe Resulting from the Invert.e Cluster Analysis with Ilray-Curtis arxl Group Average Sorting. ................................ l m 28 Table 10. Dry Weight lilomass (g/m2) for OmMrus crispur, /%yllophora spp., 'Ihe g Retnalning Benthic Species, Epiphytes, and Total Algal liiomass at the g Emuent, Maroma Point, arxl Rocky Point Stations in April 1990. . . . , . . . . . 36 Table 11. Dry Weight Iliomass (g/m2) for Omrufrus crispur, IWylbphora spp., 'Ihe Remaining Benthic Species, Epiphytes, arul Total Algal !!iomass at the Empent, Manomet Point, and Rocky Point Stations in September 1990.........,............. ........................ 37 1 1-I I I I; 1
l EXECUTIVE SUMhiARY This report represents results of quantitative data collected in April and September 1990 at established stations in the vicinity of the Pilgrim Nuclear Power Station (PNPS) and qualitttive transcct surveys conducted in the thermal ef0uent in April, June, September, and December of 1990. These investigations represent the most recent phase of the long term efforts to monitor the effects of thermal effluent on the benthic communities adjacent to the PNPS. A variety of analytical techniques were used to assess community structure. Speelne data on algal biomass, dominant fauna, species diversity, and faunal densities were analyzed along with overall community relationships. OU ANTITATIVE STUDIES Faunal Studies A total of 116 species of benthic invertebrates were found in the 1990 samples. The majority of species consisted of polychaetes (43), mollusks (40), and crustaceans (26). The total number of species recorded at the Ef0uent, hianomet Point, and Rocky Point stations were higher both in April and I September 1990 than recorded in 1989 (April 1990: EFF,69 species; hip,70 species; RP, 80 species; I September 1990: EFF,61 species; hlP,74 species; RP, 80 species). Total densities recorded at the three stations were very high in April, due in large part to high counts of the blue mussel, Mytllus edulls, The Ef0uent station was lowest in total density (about 198,000 individuals per m8), whereas the hianomet Point station was highest (more than 430,000 individuals per m*t it, hrtember the mussel counts were lower, causing a decline of total densities at all three stations. Densliy .a the Eftluent station was highest (213,000 individuals per m2); the lowest densities were recorded at the hianomet Point station (142,000 individuals per m2). In April, the 15 highest ranked species at each station accounted for approximately 98% of the total density at each station. The percentage of the 15 dominant species in September was slightly lower, ranging from 95% to 98%. The larger list of rare species (46 to 65) recorded at each station thus contributed little to total density during both seasons. Mytllus edulls, Jassafalcata, and Lacuna vincta were the first, second, and third ranked species at all three stations in April, whereas in September each station had a different suite of species in the three top ranks. A total of 20 to 23 species comprised the 15 highest ranked species at all three stations in April and September hiost of these dominant species f were amphipods (9 species in April,8 species in September), followed by gastropodt (4 species in April, 5 species in September) and bivalves (3 species in April and September). I ' I i -_ _
l Species diversity indices are obscured by the high density of Mytilus rdulls. When the mussels are removed from the analysis, the diversity values are within the range expected in near coastal benthic communities. For example, Shannon's 11' rangul from 3.35 (hianomet Point) to 4.13 (Rocky Point)in spring and from 3.06 (Effluent) to 4.35 (Rocky Point) in the fall. Community analysis by clustering or similarity techniques indicates that there was little difference between the three stations. April samples frcm the Ef0 cent, hianomet Point, and Rocky Point stations intermixed to some extent regardless of whether the Bray-Curtis or NESS similarity measures were used. De September samples from the reference stations intermixed with Bray Curtis, but the Ef0uent samples tended to group together. With NESS, the Efauent samples formed a cluster that was relatively dissimilar from the reference stations. Similarity analysis by species for both April and September revealed that dominance ptterns induenced the way the species groups joined. For example, most of the species that comprise the lists of highest ranked dominant species tend to cluster together, while the rare or infrequently encountered species comprise other groups. Algal Studies No additions to the cumulctive algal lists were made as 6 result of analysis of the April W September 1990 samples. De rock and cobble substrata found at the Ef0uent, hianomet Point, and Rocky Point stations were heavily populated with red algae, especially Irish moss (Chondrus crispus) and Phyllophora spp. Epiphytle algal species were observed at all stations, with Chondrus and Phyllophora serving as primary hests. Algal community overlap measures the similarity in algal species composition between stations, in April 1990, the percent of replicate overlap was higher at the Ef0uent station (27,7%) than for either the hianomet Point (24.0%) or Rocky Point (22.5%) stations, indicating that individual samples at the Effluent station were less similar to one another than the samples from the reference stations. Community overlap between the three stations was very high, indicating a high degree of homogeneity in species shared, in September, the ranges in percent overlap between replicates was less than in April at all stations, with the largest decrease occurring at the reference stations. The overlap between the two reference stations was almost the same in September as it had been in April, whereas the overlap between either of the reference stations and the Ef0uent station declined from April to September. These results , indicate that the replicates from each station were more homogeneous and the Ef0uent station differed more from the reference stations in September. I l
W in April, total algal biomass was highest at the Effluent station and lowest at Rocky Polnt; the reverse of this pattern was seen in the fall when the highest algal biomass occurred at Rocky Point and the lowest at the Effluent station. Blomass of Osondrus cilspus was highest at hianomet Point in April and September; it was lowest at Rocky Point in April and at the Effluent station in September. Phyllophora spp, biomass was highest at the Eftluent station and lowest at hianomet Point in April but in the fall was lowest at the Effluent station and highest at hianomet Point. The highest biomass of benthic algal species other than 0 ondrus and Phyllophora occurred at Rocky Point in both spring and I fall, ne highest blomus of epiphytic algae was found at the Ef0uent station in April and at hianomet Point in September. Analysis of variance (ANOVA) indicated no signl0 cant differences in biomass
~
l values among the three stations for either season. Q,UALITATIVE TRANSECT SURVEYS The qualitative transect studies performed to evaluate Osondrus crispus community in the thermal plume area indicate that the denuded and stunted areas have returned to a condition that is typleal of full operation of the plant. The Omndrus denuded and stunted areas encompassed 904 and 90 m$, respectively in the April 1990 survey and 1835 and 300 m1 in June. The size of the affected area in June was similar to areas affected before the 2% yr shutdowr of the plant. During the second half of the year, g the denuded zone decreased gradually to encompan an area of 1260 m2 by December. At the same time, p the stunted rene experienced a sharp decrease to 166 m' in September and a slight increase in December (180 m2). He most important observation taken during these surveys was the remarkable development of dense mats of blue mussels (Mytilus edulls) in June. The mats were so thick that the algae were completely buried under mussels that meuured I to 2 cm in length. The size of these mussels suggests that they moved to the effluent canal as postlarval plantigrades that had originally settled on filamentous red algae in surrounding areas. The continuous water 00w and warmer temperature present in the effluent area along with rock surfaces that were largely devoid of algal growth are possible attractive factors that might account for this unprecedented event. by September, only few mussels were still present north of the center line, but dense assemblages were obse ved south of the cereter line, along with a fairly large population of grazing starfish, in December, the mussel populations had declined on the south side as well. 3
I
1.0 INTRODUCTION
This report represents a continuation (under Boston Edison Company Purchase Order No. 67261) of the long term (17 yr) algal and faunal studies at Pilgrim Nuclear Power Station (PNPS) that are intended to monitor the effects of the thermal ef0uent. The program has essentially remained unchanged for the last ten years. Quantitative benthic algal and faunal sampling is conducted during the spring and fall at two reference sites, Rocky Point and Manomet Point, and at a site offshore of the ef0uent canal (Figure 1). Qualitative SCUBA surveys of algal cover in the effluent thermal plume are conducted quarterly during March, June, September, and December. This Semi Annual Report includes quantitative data from samples that were collected in April and September 1990 and qualitative observations recorded in April, June, September, and December 1990. l 2.0 MLTilODS 1 2.1 FELD SAMPLING ne sampling sites are those that have been sampled since the beginning of the monitoring program, approximately 10 years ago. The stations are located by the following established procedures. Line-of sight positions are established using highly visible structures located on the shore as reference points. He Rocky Point station is located by lining up the microwave relay tower with the PNPS red and white off-gas stack. The Efauent station, located approximately 120 m offshore, is identined along the center line between the two discharge jettles. The Manomet Point station is located by lining up the two southernmost telephone poles on top of Manomet Point. Line-of sight positioning, combined with lead line depth checks ensures station relocation to within a radius of 20 to 30 m of the original station position. All sampling is done by SCUBA equipped biologists operating from a small boat. For the quantitative algal and faunal studies, five replicate samples Jelineated by a metal quadrant that measures 0.33 m on a side (0.1089 m2) are taken from the surface of rucks at each station. g Upon arrival at a station, the divers descend to the bottom and locate suitable rocks for placement 5 of the quadrant. Divers assess algal and faunal cover and select rocks that are considered typleal for the station. All attached Dora and fauna within the quadrant are scraped from the rock and drawn through an airlift device into a 0.5 mm mesh bag (Figure 2). Field labels with station, collection date, and replicate number are placed in sample bags before sample collection. After sample collection, the bag is tied and placed in a large catch bag,and a new bag is attached to the altlift. He divers then locate the I I
M M M M M M m mM e mW W M M M M M M 5 INN 5
- i(;;f.:c i NY .Y 5.l$.w$. '
Duxbwy l C. F:t
&$&ff % fG - @sf 14tM;y.'
;ijp!2 for /
E Gurnel Point Cape Cod Day
+ Plymouth Day i
@ Rocky Pt.
@ Ef f.51.
- f. .
@ Monomel Pt.
Plymouth .. i
; yl 'D -,
4 i t
? &
s . . ff- ^l;l; s unanen .=,, L3:% f Figure 1. tecation of Benthic Sampling Sites near Pilgrim Statkm.
I Suction Lift Tube And Catch Bag veiero Edge And j ~ 7 opening 0t sample 889 12' x 18'Nytex Mesh g (0,5 mm Mesh) a
= ,
g Rubber stopper E l Heavy Surgical Tubing used in conjunction With g Hose Clamp Por Stability 3 During Sampling I Scuba Connector l Flow of Airis W Controlled $y Yank Valve only PVC Tube n " e...d Pitting I I
- l 4 - 6' Low Proseure gg, Olve Hose N
E Lead Weight (Approx.10Lbs.) h
- [
~ t Figure 2. Suction Lift Device Ur.ed by Diven to Collect Ilenthic Samples.
6 l
I next suitable rock and repeat the sampling process. After the five rep!!eates are collectoJ at a station they are delivered to a biologh.t on the boat for processing, While the vessel is underway to the next station, the contents of each bag are transferred to a 1-gal plastic jar, labeled, and preserved with 10% buffered formalin. ApproGmately 100 g of Ilorax is added to each jar as a buffering agent to prevent softening of calcified shells. For the qualitative transect survey, SCUDA observations are made along the axis of the discharge canal. A line is extended across the mouth of the discharge jetty (Figure 3). A weighted transect line, marked at 10-m intervals, is then attached to the center of this line and deployed along the central axis of the canal to a distance of 100 m offshore. A 30 m line, marked at 1 m intervals, is extended perpendicular to the transect line by the divers and oriented to the transect line with a compass. A diver swims along this third line and records changes in algal cover at 10 m intervals from the transect line through the denuded and stunted Omndrus areas to uhere the algal cover becomes normal. I According to procedures established by Taxon (1982) and followed in subsequent years, the distinction be: ween ' denuded
- and ' stunted
- rones is based on the growth rnorphology of Omndrus I crispus. The denuded zone is defined as that area where Omndrus occurs only as stunted plants restricted to the sides and crevices of rocks, in this area, Omndrus is found on the upper surfaces of rocks only I where the microtopography of the rock surfaces creates small protected areas, In the stunted zone, Omndrus is found on the upper surfaces of the rocks but is noticeably inferie in height, density, and g frond development compared to unaffected areas. The normal zone is considered to begin at the point 5 where Omndrus height and density are fully developed. In addition to observing algel cover, the divers I record any unusual occurrences or events in the area and note the location of any dirtinctive algal or faunal associations.
2.2 LAI1 ORATORY ANALYSJS In the laboratory, the algal and faunal fractions of the samples are separated by washing the animals off the algae onto a 0.5 mm mesh screen. The animals are preserved in a solution of 70% ethanol, The algal fraction is preserved in a 10% formalin solution The faunal samples art labeled and stored in IGoz glass or plastic jars until sorting, Algal samples are labeled and stored in 1 gal plastic jars until sorting, Each replicate sample is processed separately. The algal component of each sample is examined, using both dissection and compound microscopes, to identify all species of macroalgae and, in addition, record the presence or absence of 38 indicator species, important algal references used to identify and i I
I I i Discharge Canal B q Barrier Net g
- -s _
, '. % , %f 7 E
- *. , ,. . E
?Q
,. x ,
... MF Etfluent Line @. W Se at Wolght Marks at 10 - motor intervals Diver 1 I
Diver 3 Diver 2 l
; x m .._gm.
(30 meters marked off at 1 -meter intervals) 8 1,s.o , me m. , , g g Diver saf ety IJne
=
I W Aacher and Line I Figure 3. Design of the Qualitative llenthic Transect Sampling Program at Pilgrim Station. 8
I confirm names are Taylor (1957), Parke and Dixon (1976), and South (1976). Thirty seven of the indicator species were originally chosen by Taxon in September 1978, having been carefully selected from a list of the several hundred algal species recorded from the PNPS study sites between 1974 and 1978 (Taxon,1982). One species (Cadophora rpp.) was added in 1988 (BECO,1988). The indicator species include members of each of the major algal families from a variety of habitats, including all of the dominant species within the study area, the majority of the macrophytic species, and the most common epiphytic species (Table 1). Therefore, the indicator species comprise the most substantial part of the algal community as measured by both percent cover and biomass, although they constitute only a small fraction of the Cora inhabiting the study area in terms of the number of species. Dry weight biomass of all macroalgae in each sample is reported as total biomass and for four separate algal fract!ons: Osondrus crispus, Phyllophora spp., epiphytic species, and the remaining benthic species. Each fraction is weighed on a Mettler balance after being dried for 72 h in an oven set I at 80'C, A 25% aliquot of the faunal fraction of each sample is processed and the remaining 75% of the I sample is archived. Prior to sorting, the 25% aliquot is stained with a saturated alcoholle solution of Rose Bengal for at least 4 h, but no longer than 48 h to avoid overstaining. The samples are examined I under a dissecting microscope and each organism or fragment thereof removed. Invertebrates are sorted to major taxonomic groups, such as polychaetes, crustaceans, bivalves, gastropods, echinoderms, and g other miscellaneous phyla. The blue mussel Mytllus edulls is left with the residue and counted during W the sorting process. Final identincation is to the low est possible taxon (usually to species). During identl0 cation, the I counts of each species are recorded. A new reference collection for the PNpS program has been developed from the 1990 samples and will serve as a voucher collection for subsequent identincations. The samples are archived for a minimum of three years after collection. 2.3 DATA ANALYSIS - All faunal data are kept on specially designed project data sheets to facilitate computer entry. Qata are entered into a spreadsheet format on a personal computer. The software used is Quattro Pro
- Some basic data summaries and calculations can be made while the data are in this form. Following data entry and reorganization in the spreadsheet, a hard copy of the raw data is generated and verined against the original coding sheets. All entry errors are corrected at this point. Data Gles are then transferred to the Woods Hole Oceanographic Institution (WHOI) VAX computer for analysis.
I ' I 4
I Table 1. Algal Indicator Species used for Quantitative Community Analysis. E Chlorophyta (Green Algae) Rhodophyta(Red Algae) Bryopsis plumosa* Aht;feltla plicata
- Gaetomorpha linum
- Antilhamnion americanum
- C. melagonium* Bonnemaisonia hamifera*
Cadophora spp.* Callophyllis cristata Enteromorphaflexuosa* Ceramium rubrum
- Rhl:oclonium riparfum* Chondrus crispus
- Uhu lactuca* Corallina oficinalls*
Cystoclonium purpurcum* Phaeophyta (Brown Algae) Gracilaria Ilhahlae Gymnogongrus crenulatus Gordarlaflagell{ formis Membranoptera alata* Desmarestia aculeata* Palmarla palmata D. viridis Phycodrys rubens
- Laminaria digitata
- Phyllophora truncata*
L. saccharina P. pseudoceranoides* Sphacelaria cirrosa* P. traillil Plumaria elegans Polyldes rotundus
- Polysiphonia elongata l P. flbrillosa* E P. harveyl*
P. nigrescens* g P. urceolata* q Rhodomela cortfenvides* Spermothamnion repens *
. spees< - n - _ ,i..
I I I I E I B_
I Analytical software consists of a suite of programs developed specl0cally for the analysis of j benthic data, in addition to a variety of data management and modincation utilities, these programs i include PRAREl and COMPAH. PRAREi summatizes the data for each sample, calculates a variety of diversity related indices, and generates a rarefaction curve. COMPAH is a multivariate classincation l package that allows a wide variety of user specined optiom for similarity indices and clustering strategies, including both normal (i.e., by station) and inverse (i.e , by species) analyses. The individual species composing the fauna at each station are rank ordered by abundance. The most abundant species is listed first, followed in order by less abundant forms. The percent contribution of each species to the total fauna is denoted by a decreasing total percentage starting with the most j abundant species and ending with the most rare. Basic statistical treatments include calculation of means l of abundances per station and extrapolation to density per m2 Species richness is it.:erpreted by using a Jackknife procedure in combination with pooled species I data to evaluate the contribution of rare species in the communities (Heltshe and Forrester,1983). This procedure takes into account that random samples are not necessarily representative of a population. The l Jackknife estimate of spec!es richness is a function of the number of so called
- unique
- species present i at a station, that is those that are present in one and only one replicate out of five. The jackknife I
estimate of species richness ($) is expressed as:
$ = S+ A" N k n
I where S represents the pooled species numbers at each station, n is the number of replicates, and & is the number of unique species. The variance of estimated species richness (var ($)) is also calculated to measure the spatial distribution of unique species. Measures of diversity calculated for each sample and station include the Shannon Wiener information (H*) and evenness (l') indices and rarefaction curves constructed according to the method of Hurlbert (1971). Shannon's H' has been shown to be a biased estimator and for small samples will l underestimate true population information (Smith and Grassle,1977). Hurlbert's expected species index of diversity is an unbiased estimator and is thus particularly useful when small and unequal sample sizes must be comprired. I " I l
I ne measure of similarity developed by Grassle and Smith (1976), the Norinalimi Expectni Species Shared (NESS), combined with group average sorting is used for cluster analysis. NESS is based g, on the expected number of species shared between random samples of size m drawn from a population, a and is sensitive to the less common species in the populations to be compared. For the present analyses, m was set at 200. He Bray-Curtis similarity measure, combined with group average sorting, is also used (Boesch, , 1977). Rese values are calculated for stations (normal) and species (inverse). For the latter, data are analyzed using numbers of individuals, l in order to evaluate patterns in the station and species similarities, a nodal analy. is is performed using the results of the similarity analyses described above. This procedure is espechily useful when evaluating the combined spring and fall data. Nodal analysis is a method of relating normal and inverse class 10 cations to aid in the interpretation of cluster analyses, ne method uses two way tables that show replicate groups on the vertical side and species groups on the horizontal side, nis technique is used i to measure constancy and fidelity. Constancy is a proportion derived from the number of occurrences of a species group in a replicate group as compared with the total possible occurrences. Fidelity is the degree of restriction of a species group to a replicate group. For the algae, community overlap was calculated using Jaccard's coef0clent of community (Grieg Smith,1964) to measure the similarity in algal species composition among the Efnuer,t, Manomet Point, and Rocky Point stations. Jaccard's coef0clent provides a mathematical evaluation of the similarity between two repUcates or stations using only species occurrence and does not consider differences in their abundance. Comparison of means in a single classification Model I ANOVA (Sokal and Rohlf,1969), for each season separately, were performed to determine whether there were any differences among stations in algal biomass. Sources of variation were among stations (df=2) and within stations (df= 12); F,y
= 3.89.
I I E u g i
.I 3.0 RESULTS 3.1 OUAN'ITTATIVE FAUNAL MONITORIN1 3.1.1 Systematics A total of 116 species were identified from samples taken in April and September 1990. The fauna consisted mostly of polychaetes (43 species,37%), followed by mollusks (40 species,34%) and crustaceans (26 species, 22%). The remaining seven species consisted of echinoderrns, anemones, nemeneans, sipuncullds, tunicates, and oligochaetes. A list of the species collected in 1990 is presented in Appendix A. The number of species from the combined spring and fall samples agrees well with the expectations based upon the spring results (DECO,1990b). In an environment like that of the monitoring l stations about 100 to 150 species are expected to be present at any one time; the exceptionally high numNr of species (well over 400) reported in previous years reflected taxonomic inconsistencies on one hand and the occasional presence of single individuals belonging to rare or untypical species on the other hand. He current species list will probably be expanded over time as a few such rare species are , I l encountered. . l 3.1.2 Species Richness I. Species richness values for all three stations for April (spring) and September (fall) 1990 are g presented in Table 2. Data are presented as total species per replicate for each station, with a mean value W over all replicates at each station and a cumulative total representing pooled species numbers at each in April 1990, the Rocky Point reference station had 80 species in all for pooled replicates (average per replicate: 48.2), the highest number among the thne stations. Manomet Point followed Rocky Point with 70 species (average per seplicate: 47.6), and the Effluent station had 69 species (average per replicate: 39.0). An analysis of variance (ANOVA) that compared the mean number of species occurring at each of the stations indicated no significant difference. In September 1990, the conditions were essentially the same. The Rocky Point station had the highest number of species (80, average per replicate: 54.2), followed by the Manomet Point station (74 species, average per replicate: 48.4) and the Effluent station (61, average per replicate: 39.2), in order to assess the rare species that might be present at the stations but were not found because of the relatively small area sampled, the jackknife estimate of Heltshe and Forrester (1983) was calculated (see Section 2.3), resulting in an estimated species richness value (S). In April, the estimated I I
Table 2, Faunal Spocles Richness at the Ef0uent, Manomet Point, and Rocky Point Stations in April and Scptember 1990. Ehent Manomet Nint RxLy Point spring rau spnng rau Spring Fall No. $ruies'Repticate 41,41,42, 42,38,27, 48,46,41 $ 1, 48, 47, 51, $0, 52, $4,04,49, 30,41 $0,39 $1, $2 43,53 45,43 53, $1 Mean 1 StanJard 39.0 1 39.2 1 47.6 1 48.4 1 48.2 i $4.2 1 Deviation $ A4 8.29 4.39 3.85
- t 96 $ 81 No. Specica/ station 69 61 70 74 s0 80 hckknifed Estimate 91.5 74.8 66.3 97,8 108.8 101.3 Species Richness ($1 Yariance ($) 15.36 5 44 19.36 13.04 13.76 16 96 species richness was highest at Rocky Point, followed by the Effluent station and hianomet Point, i.e.,
when rare species were considered, the Ef0uent station ranked between the two reference stations rather than below them, ne variance was highest at the hianomet Point station, suggesting that the rare species were distributed unevenly among the replicates from that station. In September, the estimated species richness values did not differ as drastically from the species numbers actually observed in the samples. Species richness at all stations was higher during both seasons of 1990 than it had been in 1989. Seasonal changes in species richness were mixed (decline at the Ef0uent station, increase at hianomet Point, no change at Rocky Point), as was the case in 1989 when there was no change at the Ef0uent station, a decline at hianomet Point, and an increase at Rocky Point. 3.1.3 Faunal Demity I Table 3 shows the faunal densities for each station and season, presented as mean number of individuals per replicate (extrapolated from the individuals counted in the 25% aliquot) and the density per m2, Because the area included within each replicate is 0.1089 m2, the total density at each station represents a total area of 0.5445 m', Generally, densities were very high in April, but declined to moderate values in September, in the spring, density at hianomet Point was by far the highest (about 420,000 individuals /m2), and the Ef0uent station ranked lowest (about 199,000 individuals /m2), in the fall, the Efauent station had the highest densities (;14,000 individuals /m2), and Rocky Point had the i4 g 1 1
ll u WillEum'11 u Table 3. Faunal Densities at the Efnuent, Manomd l'olnt, and Rocky I'olnt Stations in April and Smtember 1990. Density Total Fauna Afyrilus edulis Remaining Fauna station Se w n hican (R) No. Density hican ( X) No. Density hican (R) No. Density Indiv./ Rep, per m8 Indiv./ Rep. per m8 Indiv./ Rep. per m2 Spring 21,570 198.075 16,506 151,574 5,064 46,501 l Fall 23,294 213,899 13,425 123,277 9,869 90.622 Spring 45,775 420,342 36,182 332,253 9,593 88,089 Fall 15,504 1d2,369 9.155 84,070 6,349 $8.299 Spring 29,823 273,851 24,609 225,976 5,214 47,875 Fall 18,975 174,244 12,877 118,244 6,098 56.000 lowest densities, with about i14,000 individuals /m2 Both reference stations showed a considerable decline in total faunal densities from spring to fall, whereas densities at the Ef0uent station increased slightly. These shifts in total density were largely in0uenced by the mussel, Afytllus edulls; the large impact of the mussels on density was to be expected because they regularly comprise well over 50% of the entire fauna. Consistently high densities of mussels have been observed since 1988, preceded by a year of very low Afytilus density (DECO,1988). However,the increasing total density at the Efnuent station has to be attributed to species other than Afytllus, because the mussel densities decreased from April to September at about the same rate at all three stations. Figure 4 shows the densities per replicate of the three most abundant species in April and September Total densities per replicate are also presented. From these Ogures it is evident that the amphipod Jassafalcata is the most important species that innuenced the total density at the Ef0uent station (Fig. 4C). Lacuna vincta, the other top dominant aside from the mussels, experienced a more or less pronounced decline in densities between the spring and fall (Fig 4D). During the previous year, densities at the reference stations showed a similar tendency, whereas the Efnuent station was unusual because of exceptionally low densities in April followed by a sharp increase in September. Again, Afytllus was not the only factor innuencing this development; although the number of individuals increased, the contribution of mussels to the fauna remained constant at about 69%.
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1 3.1.4 Speeles Dominance The 15 numerically dominant speeles collected at tu Eftluent, hianomet Point, and Rocky Point stations in April and September 1990 are shown in Tables 4 through 6. Data are presented as the average number per replicate (25% allquot) and percent contribution to the total fauna, in the spring,20 species comprised the top 15 dominants at all three stations combined. The majority of these species were amphipods l (9 species), gastropods (4 species), and bivalves (3 species), including the usual dominant, Afytilus rdulls. l Eleven of the 20 species occurred at all three stations; 3 species were shared between two stations, and 6 species were dominant at only one station (2 species at the Efiluent,3 species at hianomet Point, and 1 species at Rocky Point). The three top ranking species, Afytilus edults, Jassafalcata, and Lacuna vincia, were the same at all three stations. In the fall, the stations differed in terms of the dominant fauna. A total of 23 species comprised the top 15 dom!nants at all three stations combined, and again most of these species were amphipods (8 species), gastropods (5 species), and bivalves (3 species). Ilowever, more phyla were represented by the fall dominants than were by the spring dominants; for example, a decapod, an anemone, and an echinoderm were among the fall dominants, but not among the spring dominants. Onl i6 out of 23 species were shared among all stations in September; 10 species were shared between two stations, mostly between the reference stations (6 I species); and 7 species were found among the dominants of only one station, mostly at the Eftluent (5 species). Aside from Afytilus, the top 3 ranks were occupied by a different combination of species at each station, nese trends are also apparent when comparing the dominants in spring and fall at each station separately. At the Eftluent station, only 7 of the 15 top dominants were the same in spring and fa'l, and only I the two highest ranks were occupied by the same speeles. At hianomet Point and Rocky Point,9 and 8 of the top 15 dominants, respectively, were the same in spring and fall, and the 3 highest ranks were occupied I by the same species (with ranks 2 and 3 switching position at hianomet Point and rank 2 differing at Rocky Point), Generally the contribution of amphipods to the dominant fauna declined between spring and fall, whereas the contribution of gastropods increased, and more major taxa were represented in fall than in spring. Due to a decrease in the mussel population between spring (77 to 83% of the total fauna) and fall (58 to 68%), the number of species composing 90% of the fauna increased from 3-4 to 511, respectively, I I I " I
I Table 4. Fifteen Most Abundant Species at the Efiluent Station in April and Sm(embof 1990, f 13n.UINT Spring 1990 l'au IWO Maan I% sess of = Meas thess of Nuader Westifaml Nunder Mostified per Iauna per Founs Specha Reptkaia Srwies ,--Espliana Mysilus eduhs (halve) 4,126.6 76.52 Myelar edulis (Bivalve) 3,356.2 57M Jassa/akasa (Amphin=!) 330.0 6.11 Jasia/akasa (Anthlpod) IC04 4 17.25 lacuna itwas (Castroptal) 221.4 4.10 Metruium ernlle (Anemane) 382.4 6.57 Corophium acusum (AnthipW) 129.6 2.40 Corophium subtrestatum (ArrthipoJ) 276.4 4.75 hwuctewis frierieus (Anthipod) 124.2 2.30 lecwie iiricsa (Oastritod) 210 8 3.62 g Calhopius lar>4sculus ( Arrehiptuf) 20 4 1.49 Corophium aculum (AnyhipoJ) 136.2 2.34 tschymerw ansuipes (Anthipod) 68.5 1.28 CrepiJula plana (Gostnyod) 65.0 1.12 Capnlla penaruts (Caprethd) 49.5 0.92 JJossa behhlea (1=ycJ) 54.8 0.94 Desamins shes (Anghipinf) 40.6 0.75 Crepuul.tfornicata (Os Anyod) 52.0 0 69 Aruunta simples (Bivalve) 36.2 0.67 Caprvila penansu (Caprethd) 45.6 0.78 IJossa phosphorva (Impen!) 32.0 0.59 CorvphJum icidioswn (Anthlpud) 37.6 0.65 Corophium bonath (Ant hi rd) 29.4 0.55 IJossa phosphorea (Imyod) 37.4 0.64 probolo4Jes holm<st (Amphipod) 15.6 0.29 D<iamine Asa (Amphinnf) 16.8 0.29 Onoha scul<a (Gastnyod) 12.2 0,23 Cancer irrvratus (Duspod) 16.0 0.27 Molpula sp. (7ursste) 9.2 0.17 Mirreue lunase (Castropu!) 15.6 0.27 TUTAL OF 15 $PrrtES 5,306.0 98.37 TOTAL OF 15 SPECLES 5707.2 97.98 REM AINtNO IDENTIMED FAUN A - 66.6 1.63 RTM AINING IDENTinED FAUN A - 116.2 2.02 54 5PECtES 46 $PEctEs TUTALIDERTinED FAUNA 69 5,392.6 100.00 TOTAL IDEt(tined FAUNA 61 5823.4 100 00 SPictES $PECIr.$ 5 I I I I I I
1 l I Table 5. Fifteen Most Abundant Species at the Manomet Point Station in April am! September 1990. I MANOMt.T ICINT I Spring 1990 Fs:11990 Meae Perurs of Meam Pmess of Nuscher Ucutified Nunder Messified I per Founs per Fauns __Specise Reptkate Specica Reptkata Myrifw eduhs (Bivalve) 9, 45.6 79.N Mysilus tJuhs (Bivalve) 2,288.8 30.05
/assefakasa (AmphipoJ) 871.6 7.61 Lacuna Hncsa (GastropoJ) 377.2 9.73 Lacuna wacia (Gastropod) 378.0 3.30 /assafakasa (Anthipcd) 232.0 5.99 Ischymetrus angulpes (ArnphipoJ) 269.2 2.35 Ccmphlum bonclu (Amphipod) 200.8 5.18 E Ponsogencia inermis (Anphipod) 146.0 1.28 Margarises Athemus (GastnyoJ) 92.0 2.37 Corpphium bonsul (Asnphip(4) 122.8 1.07 Molgula sp. (Tunisste) 73 4 1.89 Capreda praansts (Caprellid) 106.4 0,93 /Jous phosphorta (loopoJ) 50.0 1.29 Deramina shes (AnphipoJ) 100.4 0,88 Amphisor rubrica44 (AsnphipoJ) 48.8 1.26 Corophium acusum (AmphipoJ) 72.0 0.63 Corcphium acusum ( AsnphipoJ) 47.6 1.23 i Onobs aculva (Gastitpod) 39.4 0.34 Niascua airsica (Bivalve) 47.2 1.22 Margarius h<hetaus (GastropoJ) 36.0 0.31 Mistrua lunasa (GastropoJ) 43.4 1.12 t> thaude airsica (Bivalve) 34.0 0.30 asuriasforbeit (rehinoderm) 41.8 1.08 Caniopius larasculus (Amphipod) 32.0 0.28 Caperus penana's (CaprelliJ) 38.8 1.00 Photoe minusa (Polychaets) 22.2 0.19 Dexamine sAsa (AmphipoJ) 37.6 0.97 Pl<urymus glaber (Amphipod) 21.2 0.19 pleurymus f labar(Arnphipod) 35.2 0.91 I TOTAL OF 15 SPECIES REMAINING IDENTIFIED FAUN A .
35 SPECIES 11,296.8 147.0 98 70 1.30 TOTA 1.OF 15 SPECIES REMA1NING IDrNrtr!ED FAUNA. 59 $PECIES 3.654.6 221.4 94.29 5.71 TorrALIDENTIFIED FAUNA 70 11,443.8 100.00 TOTAL IDENrtrIED FAUNA 74 3,876.0 100.00 5 $PECIES SPECIES I I I I I I
E Table 6. Fifteen Most Aburdant Species at th0 Rocky Point Station in April ard September 1990. ROCKY IUIMr Spring 1990 Fall 1990 Me.aa Ivesese of Meam hness of = Nurubet unasified Naudiet Manurand Specise per Fauna per Fauas e Replac4ts Species Reptw-aae Mysdur <Juhs (Bivalve) 6,152.2 82.52 Mytilus <Juhs (Bivalve) 3,219.? 67.86
/ausfalcata (Arnphipnd) 214.8 2.88 Comphium bonsui(Anthlpod) 226.2 4.77 Lacune uncia (Oastropod) 198.4 2.66 Lacuna vencia (Otstropal) 174.4 3.68 1schymcarus angulpes (Amphipod) 135.0 1.81 Margan <s A<licuua (OsstropoJ) 170.4 3.59 Comphium bonale (ArnphipoJ) i12.0 1.50 Amph40, rubricosa (Anthipod) 138 6 2 92 5 Desamin, shes (AnthipoJ) 101.0 1.35 /ausfalcata (Amphipod) 135.0 2.85 Ponsogensia inermis (Arnphipod) 99.4 1.33 JJossa phuphores (1stoJ) 71.0 1.30 Comphium acusum (Anthipod) 48.2 0.65 Deaamins this (Anthipod) 69.4 1.46 Onoba sculta (OostrupoJ) 43.4 0.58 krephium scutum (Anyhipt4) 39 6 1.26 Margartses Ashcinus (GastnyoJ) 42.4 0.57 Onoba sculta (OostropoJ) 32.4 1.10 =
CapreHa penanns (Caprillid) 30.8 0.4 i fli44,ua errelse (Bivalve) 48.6 1.02 Anomia simpler (Bivalve) 30.8 0.41 Mo!gula sr. (Tunicste) 42.6 0.90 g Caluopius laswaculus (AnphipoJ) 30.4 0.41 Pleurymics glabar ( Anyhlpod) 41.0 0.86 Omalogyre asomus (OastnpoJ) 28.0 0.38 Orridula plana (Oastropal) 31.0 0.65 Molsula sp. frunicate) 25.0 0.34 Crrndulafomicata (OsatropoJ) 28.8 0.61 TOTAL OF 15 SPrflu 1,291.8 97.80 TOTAL OF 15 SPrriu 4,508.2 95.03 REMAINING IDENTIFIED FAUNA . 163.8 2.20 REM AINING IDENTIFIED FAUN A - 235.6 4.97 " 65 $PECIES 651PECIES TUTAL IDENTIFIED FAUNA 80 SPrrtu 7,455.6 100.00 TOTAL IDEKrlFIED FAUNA 80 SPEClu 4,743.8 100.00 h3 I I I I I 1
I 3.1.5 Species Diversity Species diverslty values for both spring and fall are presented in hl lu 7 and 8 For consisteney with l previous reports, values were calculated with and without Afytilus niulls, in se spring, the Ef0uent station had the highest diversity (11'= 1.64), and the lowest diversity was found at the Rocky Point station (11'= 1.39). When Afytllus was excluded from the analysis, the Ef0uent station was intermediate between the Rocky Point and hianomet Point stations, and the 11' indices ranged from 3.35 to 4.13. In toe fall, diversities j were generally highet than in the spring, with the 11' indices ranging from 2.28 to 2.63 with Afytllus inchided. The Ef0uent station now ranked lowest, whereas the highest diversity was found at hianomet Point. When Afyrilus was excluded, diversity was stilllowest at the Efuuent, but Rocky Point had the highest diversity. The 11' index values were similar to the ones calculated for the spring samples. 130th the spatial and the temporal changes in diversity in 1990 were very similar to those recorded in 1989. When diversities were evaluated with flurlbert's rarefaction method, the Ef0uent station occupied the same ranks as it did in terms of the 11' indices, whereas the ranks of the reference stations switched both in the spring and fall when Afytilus was included. For example, in April the number of species per 5000 individuals was 48.1 at the Ef0uent,41.9 at hianomet Point, and 47.6 at Rocky Point; in September, the I corresponding numbers were 43.2 at the Ef0uent,54.8 at hianomet Point, and 60.2 at Rocky Point (Figure , 5). When Afytllus was excluded, both diversity measures produced the same rankings among stations in both 5 seasons, g The combined results obtained with these two different methods indicate (1) that Afytllus obscured the 5 diversity at the reference stations more than at the Ef0uent station in both seasons, and (2) that it' was innuenced most strongly by Afytllus in the spring. I I I I l l 21 l I
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1 I l 3.1.6 Community Analysis l Similarity Analysis by Station Similarity among stations was measured both with Bray Curtis and NE3S (Grassle & Smith,1976). Bray-Curtis tends to be innuenced by the presence of single species with high abundances such as Mytilus edulls, whereas NESS is more sensitive to rare species. Analysis of the April samples with both methods produced two large clusters composed of replicates from all three stations, with four f the Ove Ef0uent samples grouping closer together with NESS (Figure 6A). Similarity among all stations was generally t.igh; all repNates were similar at a level of 0.86 in the NESS d ndrogram. When analyzed with Bray Curtis, the Septen-ber samples all fell into one large cluster except for three replicates of the Ef0uent station that formed two clusters containing two and one replicate, respectively These clusters were entirely dependent on the number of mussels and therefore contained !!ttle information. The NESS similarity analysis produced a much more informative dendrogram (Figure 6B). Two distinct clusters emerged, one consisting of the reference stations and the other consisting of samples from the Ef0uent station. The clusters joined at a relatively low level of similarity (0.55). When both NESS dendrograms are compared, the Ef0uent samples tend to group together, a trend that was more evident in the fall than In the spring. This trend is more clearly visible when all spring and fall samples combined are analyzed. Figure 7 shows the dendrogram resulting from a Bray Curtis analysis by station with replicates combined and group average sorting. This analysis confirms the Ondings from the separate analyses of spring and fall samples: (1) seasonal differences were much greater than differences in the spatial distribution of the benthic infauna; and (2) the Ef 0uent station was much less similar to the reference stations in the fall than it was in the spring. I I l g; I I' I l I_'
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w-Figure 7. Similarity Analysis with Bray-Curtis and Group Average Sorting, April and September 1900, Replicates Pooled. Similarity Analysis by Species The 50 most abundant species in both the spring and fall samples combined were used for the similarity analysis by species. Bray Curtis was the similarity measure used. The resulting dendrogram is shown in Figure 8, and the' species that composed the ten main clusters are listed in Table 9. Each cluster .contains up to nine species, and the composition of these clusters generally followed dominance patterns
-established by rank ordering the samples. Group I contains species that were dominant at the Effluent, and occasionally at Rocky Point, in the fall; groups 2 and 4 consist primarily of non dominant species present in the fall and spring samples, respectively; group 3 consists of non-dominants present in both sprin;; and fall samples; group 5 contains mainly species that were dominant at the reference stations in the fall; groups 6 26 l a_
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I Table 9. Species Groups Resulting from the Inverse Cluster Analysis with 11 ray-Curtis and Group Average Sorting. I Group 1 Group 5 Crepidula plana Hiatella arctica Crepidulafornicata Pleusyntes glaber Idotea balthicn Afolgula sp. Corophium irtsidiosum Onoba aculea Idotea phosphorra Group 2 Afargarites helicinus Amphltoe rubricata l Cancer irroratus hfitrella lunata q Oligochaeta Asterias forbesi
. Polygordius np, a Petricola pholadformis Group 6 Nassarius trivittatus l Eulalia viridis Detamine thea Caprella penantis Group 3 Corophium acutum lschyrocerns anguipes Strongylocentrotus droebachlertsis Pontogencia inennis g Amphlpholls squamata Hannothoe imbricata Corophium bonelli l Nicolea wsterlmla Group 1 Phosocephalus holbolli Nemertes Pholoe minuta
- Acanthodoris pilosa Omalogyra atomus Group 4 Proboloides holmesi .&
Calliopius laevisculus 9 Anomia squamula Ophiopholis aculeata g. Caprella linearis Group 8 Ncrc!: pelagica l Caprella nr septentrionalis - hietridium senile . Anomia simple.s Spisula solidissima . Corophium tuberculatum h M Diaphana minuta - Group 9 Naineris quadricuspida l Cerastoderma pinnulatum Jassafalcata g Lacuna vincta Group 10 blytilus ehtis I I u g a_
I and 7 conskt mostly of dominants present in the spring; group 8 consists of fall dominants at the Ef0uent; and groups 9 and 10 contain the three species consistently dominant at all stations. Nodal Analysis To better understand the results of the similarity analyses, a nodal analysis that compares the station groups with species groups was made. Two measures were calculated: constancy, which shows the frequency of a species group at a station group compared to its frequency at all station groups combined; and fidelity, which shows how restricted or faithful a species group is to a station group. The highest possible constancy value 1: 1.00, indicating that all species of a species group occurred at all stations of a station group; the lowest possible value is 0, indicating that none of the species of a species group occurred at any station of a station group. Fidelity values are between 0 (all species of a species group are evenly distributed over all stations) and > 3 (all species of a species group occurred at only one station). The results are presented in Figures 9 and 10. Both figures utilize an abbreviated version of the station and species dendrograms, with the station groups on one axis and the species groups on the other. The matrix shows the intersections of each species group with each station group; the width of each field reflects the number of stations and species comprising the respective groups. Both the constancy and Odelity diagrams show that species groups 5,6,9 and 10 exhibited neither spatial noc seasonal distribution patterns; the groups are characterized by uniformly high constancy (frequent I occurrences) and very low to low Gdelity (little restriction to one station). Species group 8 is the only group that shows a seasonal pattern. It was absent from all spring samples, whereas in the fall it exhibited very high 5 constancy / high fidelity at Rocky Point and high constancy / moderate fidelity at the Effluent station. A spatial pattern can be seen in the fall, when species groups 3,4, and 7 showed lower constancy and, for the most I part, lower fidelity at Rocky Point than at the other two stations. Species group 8 is thus the only group with constancy and fidelity values differing from those at the reference stations in the fall, and it may be in part responsible for the formation of the separate Eftluent sample cluster (Fig. 6B). As mentioned, group 8 consists of two species that were among the top dominants at the Effluent station in the fall. The nodal analysis does not provide any information as to why the spring samples of the Effluent and Rocky Point stations were more similar to each other than any of them was to the Manomet Point samples. I I 2, g I ..
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I l 3.2 OUANTITATIVE ALGAL MONITORING 3.2.1 Systematics , No additions to the cumulative algal species list presented in Semi Annual Report No.16 (BECO, 1980) were made as a result of the analyses of the April or September 1990 samples. The 28 species found in 1990 samples are indicated in Table 1. 3.2.2 Algal Community Description The habitats and associated algal and faunal communities found at the Manomet Point, Rocky Point, and Ef0uent subtidal stations are typical of shallow, exposed areas in western Cape Cod Day and have been well documented by Grocki(1984) and Davis and McGrath (1984). The rocky substrata characteristic of all three stations are covered with dense macroalgal communities typically dominated by two species, Chondrus crispus and Phyllophora spp. In 1990, red macroalgae moderately colonized the rock and cobble substrata found at all three stations. Two thirds of the species collected both in April and in September belonged to the Rhodophyta (red algae), in addition to the dominant species Choruirus crispus and Phyllophora spp., other benthic rhodophytes included Ahtlfeltlaplicata, Corallina oD1cinalls, and Polyides rotundus. Eplphytic rhodophytes found in all April replicate samples were Ceramlum rubrum, Cystoclonium purpureum, blembranoptera alata, Polysiphonia harveyl, and Spermothamnion repens. O(these, blembranoptera alata was totally absent from the Ef0uent station in September, although present in 90% of the reference station replicates. Other species collected in all April and September samples were the chlorophytes (green algae) Chaetomorpha linum, C. melagonium, and Rhl:oclonium riparium; and the phaeophyte (brown alga) Desmarestla aculeata. Biomass of Chondrus crispus was highest at Manomet Point in April and September. The Ef0uent station had the highest biomass of Phyllophora spp. and epiphytic algae in April but the lowest of both in the g fall. The highest biomass of the remaining benthic species was at the Rocky Point station in both April and E September, Gracilaria tlkvahlae, an indicator of warm water, was not collected in any of the replicate
- samples in either April or September 1990. However, the divers observed a dark red species, believed to be GracIlaria, within the denuded zone between 10 and 30 m along the transect line at the Ef0uent station during the April, June, and December surveys.
l 3.2.3 Algal Community Overlap Community overlap was calculated for April and September 1990 data using Jaecard's coefficient (Grieg-Smith,1964) to provide a mathematical evaluation of the similarity in algal composition between pairs l 32 a_
I of replicates or stations. Jaecard's coefficient uses only sper'es occurrence and is not in0uenced by differences in abundance. Species occurrence records of the 28 indicator species found in 1990 (Table 1) were used for these calculations. Comparisons between replicate samples for each station for April and September 1990 are presented in matrix form in Figures 11 and 12. Overall, the similarity of all three stations was high, ranging from 88.9% to 96.3% in April and from 80.0% to 96.0% in September, in April, community overlap was very high for all three pairs of stations, indicating a high degree of homogeneity in algal species present at all three stations, in both April and September, community overlap was higher between the two reference stations (96.3% and 96.0%, respectively) than between either the hianomet Point and Ef0uent stations (88.9% and 80.8%, respectively) or between the Rocky Point and Ef0uent stations (92.6% and 84.6%, respectively). This result indicates that in both April and September the algal communities at hianomet Point and Rocky Point were more similar to each other than either was to the community at the Efnuent station, in September, community overlap between hianomet Point and Rocky Point was almost the same as it had been in April (96.0%), but overlap between the other two pairs of stations had declined to 80.8% for the hianomet Point - Eftluent station pair and to 84.6% for the Rocky Point - Efnuent station pair, evidence that the Efnuent I station had become less similar to the reference stations than it had been in April. I The range in percent overlap between replicates at the Ef0uent station was slightly higher in Aprit (27.7%) than in September (24.6%), sugesting that the replicates were more similar in the fall than in the spring. A much larger difference was seen at the reference stations. At both the hianomet Point and Rocky I Point stations the range in percent overlap between replicates was much greater in April (24.0% and 22.5%, respectively) than in September (12.6% and 8.7%, respectively). This indicates that in September the replicate samples from the reference stations were much more similar to each other than those taken in April. 3.2.4 Algal Biomass Owndrus crispus Omndrus crispus biomass was measured at the Effluent, hianomet Point, and Rocky Point stations in April and September 1990 (Tables 10 and 11, respectively). In April, the range of individual biomass values was greatest at hianomet Point (39.57 to 325.25 g/m2), followed by the Effluent station (18.18 to 180.57 g/m2), and Rocky Point (43.61 to 128.98 g/m2). At the Efuuent, hianomet Point, and Rocky Point stations, mean Chondrus biomass was 34%,48%, and 31%, respectively, of the total algal biomass. I I l I
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I l Table 10. Dry Weight Diomass (g/m2) for Owndrus crispus, Phyllophora spp., The Remaining Dendile Species, Epiphytes, and Total Algal Diomass at the Effluent, Manomet Point, and Rocky Point Stations in April 1990. I Chondrus crhpus Phylkphora spp. Remaining llenthic Epiphytic Species All 3 Station / Spnies (Total) Algae g Replica'e 4 liiomats Percent Iliomass Percent linomass Percent liiomass Percent hmass EFF1 148.62 36.76 163.50 40.44 5.60 1.39 86.57 21.41 404.28 EFF2 158.81 28.55 215.18 38.68 62.97 11.32 119.34 21.45 556.29 EFF 3 88.40 28.46 135.77 43.72 5.88 1.89 80.51 25.92 310.56 EFF 4 180.57 44.98 125.49 31.26 13.77 3.43 81.61 20.33 401.44 EFF 5 18.18 19.51 14.41 15.46 29.38 31.53 31.21 33.49 93.18 R EFF 118.92 33.67 130.87 37.06 23.52 6.66 79.85 24.52 353.15 htP 1 97.58 37.61 16.98 6.55 12.58 4,85 132.28 50.99 259.43 h1P 2 39.57 20.38 105.48 54.33 13.22 6.81 35.89 18.48 194,16 blP 3 325.25 75.14 51.87 11.98 0.83 0.19 54.90 12.68 432.84 hlP 4 103.83 39.88 98.59 37.87 5.97 2.29 51.96 19.96 260.35 W htP 5 101.26 42.67 80.33 33.85 21.02 8.86 34.70 14.62 237.32 I h1P 133.50 48.23 70.65 25.52 10.72 3.87 61.95 22.38 276.82 RP 1 60.59 45.90 33.87 25.66 19.37 14.67 18.18 13.77 132.01 RP 2 50.21 24.00 86.66 41.46 47.92 22.92 24.24 11.60 209.03 RP 3 128.98 38.19 62.52 18.51 32.22 9.54 114.02 33,76 337.73 RP 4 52.88 34.76 48.29 31.74 20.20 13.28 31.95 21.00 152.12 RP5 43.61 17.50 159.64 64.05 26.53 10.64 19.46 7.81 249.24 R RP 67.25 31.13 78.20 36.20 29.25 13.54 41.57 19.24 216.03 EFF: Emuent; htP: hianomet Point; RP: Rocky Point; R: hican bionuss I I I I 36 5
Table 11. Dry Weight Biomass (g/m2) for Owndnu crispus, /Wyllophora spp., The Remaining Benthic Species, Epiphytes, and Total Algal Biomass at the Efnuent, Manomet Point, and Rocky Point Stations in September 1990. I Chondtns crnpus Phyllophora spp. Remaining llenthic Epiphytic Species All Station / Spaies (Totah Algae Replicate
% mass Percent % mass Percent liiomass Percent liioman Percent fliomass EFF1 7.44 5.07 73.35 49.94 25.98 17.69 40.12 27.31 146.89 EFF2 0.00 0.00 94.00 47.45 41.31 20 85 62.79 31.70 198.10 EFF 3 57.65 45 64 2.48 1.96 13.22 10.47 52.97 41.93 126.32 EFF 4 0.55 0 42 43.70 33.10 29.65 22.46 58.11 44.02 130.01 EFF 5 9.55 3.21 154.96 52.07 80 69 27.11 52.42 17.61 297.62 R EFT 15.04 8.35 73.70 40.90 38.17 21.18 53.28 29.57 180.19 htP 1 104.01 21.41 210.22 43.2R 83.35 17.16 88.13 18.14 485.71 htP 2 31.49 13.20 86.75 36.37 9.09 3.81 111.17 46.61 238.50 hlP 3 27.82 11.80 94 83 40.23 37.82 16.04 75.25 31.93 235.74 htP 4 98.96 32.58 91.98 30.28 15.42 5.08 97.41 32.07 303.77 h1P 5 142.47 33.23 226.20 52.75 4.02 0.98 55.90 13 04 428.79 R hlP 80.95 23.91 142.00 41.95 29.98 8.86 85.58 25.28 338.51 RP 1 56.18 22.90 47.37 19.31 77.48 31.59 64.26 26.20 245.09 RP 2 8.45 0.34 100.06 27.76 157.62 43.72 94.37 26.18 360.50 " RP 3 166.53 47.85 69.13 19.86 35.53 10.21 76.83 22.08 348.02 RP 4 57.83 15.62 120.63 32.58 89.14 24.08 102.64 27.72 370.24 I RP 5 41.40 10.95 181.03 47.90 72 ?! 19.24 82.80 21.91 377.94 R RP 66.08 19.41 103.64 30.45 86.50 25.41 84.18 24.73 340.40 EFF; Emuent; h1P; hianomet Point; RP: Rocky Point; R: hican bioman 37
I The Manomet Point station had the highest mean biomass value for Orondrus (133.50 g/m2), followed by the Efauent station (118.92 g/m2), and the Rocky Point station (67.25 g/m2). An ANOVA showed no signincant differences between any_of the stations when mean 0:ondrus biomass values were compared. In September, the range of individual biomass values was greatest at Rocky Point (8.45 to 166.53 g/m2), followed by Manomet Point (27.82 to 142.47 g/m2), and the Ef0uent station (0.00 to 57.65 g/m2). hiean Chondrus biomass was 8%,24%, and 19% of the total algal biomass, respectively, at the Ef0uent, Manomet Point, and Rocky Point stations. The Manomet Point station had the highest mean biomass value for 0,ondrus (80.95g/m2), followed by Rocky Point (66.08 g/m2), and the Efnuent station (15.04 g/m2). An' ANOVA showed no significant differences among any of the stations when mean Ozondrus biomass values were compared. The mean biomass of Orondrus decreased at all three stations between April and September. The largest decline (118.92 to 15.04 g/m2) was at the Efnuent station. Phyllophora spp. Phyllophora spp, biomass values for April and September are given in Tables 10 and 11, respectively. In April, the range of individual biomass values was greatest at the Eftluent station (14.41 to 215.18 g/m2), followed by Rocky Point (33.87 to 159.64 g/m2), and Manomet Point (16.98 to 105.48 g/m2). Phyllophora spp. were 37% of the total algal biomass at the Eftluent station,36% ac Rocky Point, and 26% at Manomet Point. The Efauent station had the highest mean biomass value for Phyllophora spp. (130.87 g/m2), followed . by Rocky Point (78.20 g/m2), anc' Manomet Point (70.65 g/m2). No significant differences were detected e.mong the stations in April 1990 when comparing Phyllophora biomass. In September, the greatest range of individual biomass values was at the Effluent station (2.48 to 154.96 g/m2), followed by Manomet Point (86.75 to 226.20 g/m2), and Rocky Point (47.37 to 181.03 g/m 2). Phyllophora spp. made up nearly the same percentage of the total algal biomass at the Ef0uent and Manomet Point stations, (41% and 42%, respectively) and less (30%) at Rocky Point. Mean biomass values for Phyllophora spp. were in an inverse pattern to that seen in the spring: the highest value (142.00 g/m2) was found at Manomet Point and the lowest (73.70 g/m2) at the Effluent station. An ANOVA showed no significant differences among any of the sta6cns when mean Phyllophora spp, values were compared. The typical seasonal increase of Phyllophora spp. biomass from spring to fall (BECO,1987a) did occur at the reference stations but a decrease in biomass occurred at the Effluent Str. tion. I 38 a_
Biomass of Remaining Benthic Species The category called " remaining benthic species" excludes Chondrus crispus, Phyllophora spp., and algal epiphytes, but does include Chaetomorpha linum, C. melagonium, Phl:oclonium ripartum, Ahnfeltla plicata, and Polyides rotundus at all stations during both seasons, and Phycodrys rubens at all stations in the spring and the reference stations in the fall. Biomass data for the remaining benthic species for April and September 1990 are presented in Tables 10 and 11. In April, the Ef0uent station had the highest range of biomass values (5.6 to 62.97 g/m2), followed by Rocky Point (19.37 to 47.92 g/m2), and Manomet Point (0.83 to 21.02 g/m2). The largest range of biomass values in September was at the Rocky Point station (35.53 to 157.62 g/m2) and the smallest range was seen at the Efnuent station (13.22 to 80.69 g/m2). In both April and September, the percentage that the remaining benthic species contributed to the total algal biomass was greatest at Rocky Point (14% and 25%, respectively), intermediate at the Effluent station (7 % and 21 %, respectively) and least at hianomet Point (4 % and 9%, respectively). The highest mean biomass values occurred at the Rocky Point station in both spring and fall (29.25 and 86.50 g/m2, respectively); the Efnuent station had intermediate biomass values during both seasons (23.52 and 38.17 g/m2, respectively) and Mar,mr Point had the smallest values (10.72 and 29.98 g/m2, respectively). No significant differences were found among the three stations for biomass of the remaining benthic species in either the April or September samples. I Epiphytic Algal Biomass 8 Biomass values of epiphytic algae in April and September 1990 are given in Tables 10 and 11. The Effluent station exhibited the highest epiphytic mean biomass value in April (79.85 g/m2) and the lowest value in September (53.28 g/m2). In April, Manomet Point had the intermediate biomass value (61.95 g/m2) and Rocky Point had the lowest (41.57 g/m2). In September, Manomet Point had the highest mean biomass value (85.58 g/m2), followed by Rocky Point (84.18 g/m2), in April, epiphytic algal biomass at the Efnuent was 29% higher than that at Manomet Point and 92% greater than that at Rocky Point. In September, epiphytic algal biomass at the Effluent station was approximately 37 % less than at both Manomet Point and Rocky Point. In both April and September, the percent contribution of the epiphytic species to the total algal biomass was greatest at the Efnuent station (24.52 and 29.57 g/m2, respectively), intermediate at Manomet Point (22.38 and 25.28 g/m2, respectively) and lowest at Rocky Point (19.24 and 24.73 g/m2, respectively). No significant differences in epiphytic algal biomass were found among the three stations during either season. I I I
I Total Algal Biomass Values for total algal biomass for April and September 1990 are given in Tables 10 and 11. The Ef0uent station had the highest mean biomass value (353.15 g/m2) in April and the lowest value (180.19 g/m2) in September. Both the Manomet Point and Rocky Point stations experienced an increase in biomass for total algae between spring (276.82 and 338.51 g/m2, respectively) and fall (216.03 and 340.40 g/m2, respectively). In April, total algal biomass at the Effluent station was 28% greater than at Manomet Point and 63% greater than at Rocky Point; in September, total algal biomass at the Ef0uent station was 45% less than at either the Manomet Point or Rocky Point stations. From spring to fall, total algal biomass decreased nearly 50% at the Efauent station, but increased 22% at Manomet Point and 58% at Rocky Point. No significant differences in total algal biomass were found among the three stationsduring the spring or fall. 3.3 OUAIJTATIVE TRANSECT SURVEY I Qualitative transect surveys of acute impact zones were initiated in January 1980 and the quarterly survey frequency was established in 1982. Four surveys were performed during 1990 (April 9, June 19, September 19, and December 13), bringing the total number of surveys conducted since 1980 to 40. Results of surveys conducted from 1980 through 1983 were summarized in Semi Annual Report No. 22 (BECO, 1983). The most recent summary of the surveys conducted between 1983 and 1988 can be found in Semi-Annual Report No. 35 (BECO,1990a), along with a review of the four surveys performed in 1989, Detailed results of the April and June 1990 surveys are in Semi Annual Report No. 36 (BECO,1990b). This report will summarize the April and June 1990 surveys as well as incorporate new data from the September and December 1990 surveys. Figures 13,14,15, and 16 show the results of mapping performed by SCUBA divers. The denuded zone is the area essentially devoid of Chondrus crispus, whereas the stunted zone has Chondrus that is smaller and less dense than that growing under normal conditions. The dive team must keep in mind while taking measurements that the shallower depths to the northwest of the discharge canal preclude normal Chondrus growth. A large boulder that is nearly exposed at mean low water, and that is used as a landmark by both the Science Applications international Corporation (SAIC) and the Massachusetts Division of Marine Fisheries g dive teams, is plotted in each Ogure. This boulder serves as a visual fix for the proper placement of the W l-transect line and ensures consistency among the surveys. I a I a_
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. Figure 13. Stunted and Denuded Omndrus Zones Observed in April 1990.
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u .- _ e.3 i Figure 14. Stunted and Denuded Omndrus Zones Observed in June 1990, B: 42
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,___i Control Area Figure 15. Stunted and Denuded Ozondrus Zones Observed in September 1990.
43
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. _ p.. . .-
30 $0 tb 0 10 2O 3O M anns NORTH SOUTH Denuded Area Stunted Area Control Area Figure 16. Stunted and Denuded Chondrus Zones Observed in December 1990. 44 l
I 3.3.1 April 1990 Transoct Survey The extent of the denuded and stunted areas mapped on April 6,1990 immediately offshore from PNPS is shown in Figure 13. The denuded zone extended approximately 70 m offshore along the centerline of the transect and was asymmetrically distributed, extending further toward the northwest than to the southeast. The denuded zone covered an area of 904 m2 and was 25% smaller than in the December 1989 survey From the 10 m to 50 m mark some rocks were bare while others were covered with patches of young Chondrus, Enteromorpha, and Ulva. A dark red alga, believed to be Gracilaria tihahlae, was found between the 10- and 30-m mark of the transect. At the 60-m mark and north of the transect, many rocks within and outside the denuded zone were covered with the coralline alga, Corallina oficinalls. The stunted zone, with an area of about 90 m2 was present only on the south side of the transect. Very few mussels were observed within the survey area. 3.3.2 June 1990 Transect Survey Results of the divers' survey on June 19,1990 are shown in Figure 14. The denuded zone extended 30 m further offshore than in April, nearly reaching the 100 m mark on the transect line, and was still asymmetrically distributed around the transect line with more area northwest of the line than southeast of the line. The area of the denuded zone had doubled in size (to approximately 1835 m2) since the April survey. Between the 30 m and 40 m marks on the transect some scattered Chondrus, Gracilarla, and Ulva were seen north of the line. A very dense mat of blue mussels (Mytilus edulls), each about I to 2 cm in length, covered I the entire survey area; the mussel mat was most dense between 50 and 100 m on the transect line. From the 70-m to 90-m mark on the transect, up to 10 individuals per m2 of the starfish Asterlasforbest were seen I grazing on the mussels. The stunted zone was present on both side of the denuded zone and had tripled in area from the April survey to about 300 m2 I 3.3.3 September 1990 Transect Survey Figure 15 shows the results of the transect survey conducted on September 19, 1990. The denuded zone extended to the 100-m mark on the transect line and as in the two previous 1990 surveys was asymmetrically distributed with 60% of the area northwest of the transect line and 40% of the area southast of the line. There was a pronounced projection to the northwest at the 70 m mark where the denuded zone extended 18 m from the transect line. The area (1600 m2) of the denuded zone was 13% less tt an that found in June. I 45 I
l I Within the discharge canal there were dense assemblages of Uhu interspersed with small patches of the red fibrous alga Cystoclonium purpureum Beyond the discharge canal, the area north of the transect line had less algal coverage and fewer algal species than the area south of the line. From the 50- to 70 m mark on the transect line, Uhu was found along the center of the transect and out to 8 to 12 m north of the line and about 4 m south of the line. Fucus was present beyond the Uha, particularly on the north side of the line. Additional algal species present at the 50-m mark and beyond included Cystoclonium purpureum, which was found out to 5 m from the line, and the delicate epiphytic species Polysiphonia hanryl, which was seen at the 60-m and 70-m mark. Corallina oficinalis was also present at the 70-m mark. A few mussels were seen north of the line but many were seen to the south. These mussel beds supported a large population of starfish (Asterlas) from 40 to 70 m along the transect line. Many mussel shells were present at the 80-m mark. The stunted zone (166 m2) was only aalf as large as that found in the June survey. Three-quarters of the stunted zone lay north of the transect line bordering the northward projection of the denuded zone and extending 21 m from the line at the 80-m mark. On the southeast side the stunted zone was narrow, averaging about 2 m between the 55-m and 70-m marks on the transect line. 3.3.4 December 1990 Transect Survey The results of the divers' survey performed on December 18,1990 are mapped in Figure 16. The denuded zone extended out to 95 m along the transect line and was much more symmetrically distributed around the line than in the three previous 1990 surveys. The widest portion of the denuded zone occurred at the 50-m mark where it reached 9 m north of the transect line and 6 m south of the line. The area (1260 m2) of the denuded zone had again decreased in size and was 21% smaller than it was in September and 31% smaller than in June. Within the discharge canal, the rock was mostly bare, with only small assemblages of the red alga Cystocloniumpurpureum interspersed within patches of Gracilarla sp. As noted in previous surveys, the area north of the transect line had less algal coverage and lower diversity than the southern region. Beyond the 70 m mark where some Uh'a, Fucus, Corallina, and Cystoclonium occurred, species diversity increased. There was much less coverage by Ulva as compared to the September survey when dense assemblages were observed. No Laminaria was observed. A few mussels (Myrilus edulls) were seen at the 50- and 60 m marks; some starfish (Asterlas) were seen grazing on the mussels on the southern side of the transect. The mussel shell debris seen at the 80-m mark in September had been replaced with pebbles, presumably by wave action. Il B_
The stunted zone (180 m2) was slightly larger in area than it was in September and beyond the 40-m mark completely surrounded the denuded zone. The width of the stunted zone was generally about I to 2 m except for a 5 m wide area north of the 60-m mark on the transect line, l
4.0 CONCLUSION
S ( 4.1 FAUNAL STUDIES I l
- Species richness was lowest at the Efauent station and highest at Rocky Point both in April
'I and September 1990. Species richness decreased at the Effluent station, increased at Manomet Point, and stayed the same at Rocky Point between spring and fall. l e Faunal densities in spring were lowest at the Efnuent station and highest at Manomet Point, I whereas they were highest at the Ef0uent station and lowest at Manomet Point in the fall. Densities were generally higher in April than in September.
- Dominant species were similar among stations in April, but differed at the Ef0uent station from the reference stations in September. Densities of Mytilus edulis declined between April and September and allowed for colonization by other organisms, e.g., the anemone Metridium senile at the Eftluent station, e Species diversity was generally higher in the fall than in the spring. The Ef0uent station had the highest diversity in April, but ranked lowest in September. Mytilus affected the diversity values most strongly in the spring when its density was very high.
I e Similarity among stations was greater in the spring than in the fall. When analyzed with NESS, the Effluent samples tended to form a separate cluster, most distinctively in the fall. 4.2 ALGAL STUDES l e Alcal communities consisted mostly of red algae, including the dominant species Ozondrus
- crispus and Phyllophora spp. A few green algae and one species of brown. alga were also collected.
- Community overlan between stations was highest between the two reference stations both in April and September. The overlap between the Eftluent station and either reference station was lower during both seasons and declined between spring and fall, indicating that in the fall s, the Efauent station differed more from the reference stations than in the spring, o Mean biomass of Chondrus biomass decreased at all stations between April and September.
In April, Ozondrus biomass was highest at Manomet Point and lowest at Rocky Point. In September, Manomet Point still ranked highest, whereas Chondrus biomass was lowest at the Effluent. PhyIIophora biomass in April was highest at the Eftluent station and lowest at Manomet Point, whereas in September the two stations switched ranks. Between April and September, Phyllophora biomass increased at the reference stations, but decreased at the 47 I
I Efnuent station. Biomass of the remaining benthic species was highest at Rocky Point and lowest at Manomet Point during both seasons. Epiphytic algal blomass in April was highest at the Ef0uent station and lowest at Rocky Point, whereas in September it was highest at 3 ] Manomet Point and lowest at the Ef0uent station. Total algal biomass decreased at the 5 Effluent station by nearly 50% between April and September, but increased by 22% at Manomet Point and 38% at Rocky Point. 4.3 OUALITATIVE TRANSECT SURVEYS
- During the spring and summer, the Chondrus stunted and denuded zones returned to a condition that is typical for periods of full operation of the plant. Dt. ring the second half of the year, the stunted and denuded zones decreased to encompass 180 m2 and 1260 m2, respectively. A remarkable development of unusually dense Mytilus mats took place in June.
These populations gradually diminished until they were no longer observed in December, I 5.0 IlTERATURE 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 Co.1980. Marine Ecology Studies related to the operation of Pilgrim Station. Semi Annual . Report No - 16. Boston, MA. Boston Edison Co. 1983. Marine Ecology Studies related to the operation of Pilgrim Station. Semi Annual Report No. 22. Boston, MA. Boston Edison Co.1986. Marine Ecology Studies related to the operation of Pilgrim Station. Semi Annual Report No. 27. Boston, MA. Boston Edison Co.1987a, Marine Ecology Studies related to the operation of Pilgrim Station. Semi Annual Report No. 30. Boston, MA.
- Boston Edisoti Co. 1988. Marine Ecology Studies related to the operation of Pilgrim Station. Semi Annual Report No. 32. Boston, MA.
Boston Edison Co. s990a, Marir.c Ecology Studies related to the operation of Pilgrim Station. Semi-Annual Report No. 3S. Boston, MA.
' Boston Edison Co.1990b. Marine Ecology Studies related to the operation of Pilgrim Station. Semi Annual Report No. 36. Boston, MA.
Davis, J.D. and R. A. McGrath. 1984. Some aspects of nearshore benthic macrofauna in western Cape Cod Bay. In Davis, J.D. and D. Merriman (eds.), Observations on the Ecology and Biology of Western Cape Cod Bay, Massachusetts. Lecture Notes on Coastal and Estuarine Studies. Springer-Verlag, Ne,v York,228 pp. I t_
m Grassle, J.F., and W. Smith 1976. A similarity measure sensitive to the contribution of rare species and i its use in investigation of variation in muine benthic communities. Oecologia 25: 13-22. Grieg Smith, P.1964 Quantitative Plant Ecology Second Edition, Butterworths, Washington,256 pp. m Grocki, W. 1984. Algal investigations in the vicinity of Plymouth, hiassachusetts, in: Davis and Daniel l l hierriman (eds.): Observations on the ecology and biology of western Cape Cod Bay, hiassachusetts. Loeture Notes on Coastal and Estuarine Studies. 228 pp. Springer Verlag, NY. Heltshe, J.F., and N.E. Forrester. 1983. Estimating species richness using the jackknife procedure. Biometrics 39: 1-11. I Hurlbert, S.H.1971. The nonconcept of species diversity: a critique and alternative parameters. Ecology 52: 577 586. I Newell, R.D.1979. Biology ofIntertidal Animals, hiarine Ecological Surveys Ltd.,Faversham, Kent. 781 pP. I Parke, ht., and P. Dixon.1976. Checklist of the British marine algae. 3rd revision. Journal of the hiarine Biological Association of the United Kingdom 56: 817-843. Smith, W., and J.F. Grassle.1977. Sampling properties of a family of diversity measures. Biometrics 33: I 283-292. I South, G.R. 1976. A checklist of marine algae of eastern Canada. Ist Revision. Journal of the hiarine Biological Association of the United Kingdom 56: 817-843. Taylor, W.R.1957. hiarine Algae of the Northeastern Coast of North America. 2nd Edition. University of hiichigan Press, Ann Arbor, hil. 590 pp. Taxon. 1982. Benthic studies in the vicinity of Pilgrim Station, in: hiarine Ecology Studies Related to Operation of Pilgrim Station. Semi Annual Report No.19.
'I I
49 !
APPENDIX A.1.lST OF SPECIES IDENTIFIED AT TIIE EFFLUENT, MANOMI?I' POINT, AND ROCKY POINT STATIONS IN 1990 Smaller Phyla Pectinariidae Pectinarla granulata CNIDARIA Afetridium senile Pholoidne Anemone Pholoe minuta NEMERTEA Phyllodocidae Eteone longa S1PUNCULolDEA Eulalla viridis Eumida sanguinea Annelida Phyllodoce (Analtides)maculata OLIGOCHAETA Polygordlidae l Polygordius sp.1 POLYCHAETA Ampharetidae Polynoidae I Asabellides oculata Hannothoe extenuata Hannathoe Imbricata Arenicolidae Hannothoc spp. juv. l Arenicola marina Hannothoe spp. Indet. Lepidonotus squamatus [ Capitellidae l Capitella capitata Sabellarildae biedlomastus cal {forniensis Sabellaria vulgaris g Afedio~m astus spp. indet. Sabellidae l Cirratulidae Fabricia sabella Caulleriella bloculata Potamilla neglecta l Chaetozone setosa Chaeto:one sp. I Potamilla rentformis Sabellidae spp. Indet. Chaeto:one spp. juv. Cirratuluscirratus Sigallonidac Dodecacerla corailli Sthenelais boa Nephtyidae Spionidae Nephrys caeca Polydora cornuta Polydora socialis Nereididae Polydora absteri Nerels pelagica Polydora spp. indet. Nerels e.onata Prionosplo steenstrup! Nerels spp. Juv. SploJllicornis Splo thulini Orbiniidae Spionidae spp. juv. Naineris quadricuspida A1
I Syllidae lschyroceridae Autolytus alexandri ischyrocerus angulpes Autolytusfasciatus Jassafalcata l Autolytus prismaticus E Autolytus spp. Juv. Phoxocephalidae Exogone hebes Phoxocephalus holbolli Syllis (1)posyllis) cf. hyalina Pleustidae Terebellidae Pleusymtes glaber g Amphitritinae spp. juv. g Nicolea venustula 1ontogenelidne Nicolea zostericola Pontogenela inermis g Polycirrus eximius g Polycirrasphosphoreus Stenotholdae Polycirrus spp. Indet. Metopella angusta Polycirrus spp. Juv. Proboloides holmesi CalMagsa CAPRELLIDEA Caprellidae ISOPODA Caprella linearls Idoteldae Caprella penantis Idotea phosphorea Caprella nr. septentrionalis Idotta barthica Caprellidae spp. juv. AMPHIPODA DECAPODA B Amphitoldae Cancer Irroratus E Amphltoe rubricata Carcinus maenas Eualus puslolus g-Calliopidae Pagurus acadianus n Calliopus laevisculus Pagurus sp. Corophlidae M0Russa Corophium acutum Corophium bonelli GASTROPODA g Corophium insidiosum Acmaeldae g. Corophium spp. Indet. Acmaea testudinalis Corophium spp Juv. Aeolidildae Dexaminidae Aeolidia papillosa Datamine thea Calyptracidae Gammatidae Crepidulafornicata Gamarellus angulosus Crepidula plana Gammarus oceanicus Gammarus sp. Cerithlidae Marinogammarus stoerensis Blttlum alternatum I A-2 I
E Columbellidae Gastropoda spp. Indet. Anachis translirata Gastropoda spp. juv. Mitrella lunata Nudibranch spp. Indet. Cratenidae BIVALVIA Cratena aurantia Anomildae E Diaphanidae Anomia simplex Diaphana minuta Anomia squamula l Eubranchidae Cardlidae Eubranchus exiguus Cerastoderma pinnulatum nr. Eubranchus pallidus i Hiatellidae Facelinidae Hlatella arctica Facelina bostoniensis i Mactridae Lacunidae Splsula solidissima 1.acuna vincta i Myldae Lamellidorididae Afya arenarla l Acanthodorispilosa Littorinidae Mytilidae Modlotus modiolus l Littorina littorea Mytilus edults Littorina satatills Petricolidae Nassariidae Petricola pholadyormis i Nassarius trivittatus Tellinidae Naticidae Macoma tenta Lunatia heros Tellina agills Omalogyridae Thraciidae Omalogyra atomus lhracia septentrionalls Pyramidellidae Veneridae Odostomia dealbata Gemma gemma Odostomia gibbosa Mercenaria mercenaria Turbonilla elegantula l Rissoidae Alvania pseudareolata Blvalvia spp. Indet. POLYPLACOPHORA Lepidochiton ruber
.i Trochidae Onoba aculea 1schnochiton ruber Margarites helicinus A3 i
l I Echinodermata ASTEROIDEA g Asteriasforbes! l Henricia sanguinolenta ECHINOIDEA Strongylocentrotus droebachtensis OPHlUROIDEA Ophlopholls aculeata
. Amphlpholls squamata Tunicata POLYCLINIDAE Amaroucium con.stellatum MOLGULIDAE g Molgula sp. E I-I I
I I I I I I A-4 I
I 11NAL SEMI-ANNUAL REIORT Number 37 I (Volume 2 of 2) I , I IIENTlilC ALGAL AND FAUNAL MONITORING I AT Tile PILGRIM NUCLEAR IOWER STATION (IMPACT ON IlENTillC COMMUNITIFS) January-Docember i990 I to llOSTON EDISON COMPANY Regulatory Affairs Dwartment Liccasing Division I 2511raintree lilli Office Park Ilraintree, Massacimsats 02,84 I I From SCIENCE APPLICATIONS INTERNATIONAL CORPORATION 89 Water Stred Woods lloie, MA 02543 (508) 540 7882 I i A P ,ii i m i g I I
~ TAllLE OF CON 111NTS h EX EC UTI V E S U M M A R Y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I r I 1.0 INTRODUCIION .............................................. 3 l l 2.0 M l?I110 D S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.0 DACKGROUND ................................................ 7 4 . 0 I M P A CT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 I 4.1 QUAN11TATIVE FAUNAL COMMUNrrY STUDIES . . . . . . . . . . . . . . . . . . 9 4.1.1 Species Richness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.1.2 Species Demity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...... Il 4.1.3 Species Diversity .................................. I 4.1.4 Similarity Aneng Stations ............................. 11 14 4.1.5 Discussion- Faunal Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.2 QUAN1TrA11VE ALGAL COMMUNirY STUDIES . . . . . . . . . . . . . . . . . 18 4.2.1 Algal Community Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 4.2.2 Algal Community Overlap 18 I 4.2.3 Al gal Diomass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.2.4 Discussion- Algal Studies . . . . . . . . . . ................... 20 4.3 QUALrrATIVE TRANSECT SURVEYS . . . ...................... 25 5.0 CO N C LU S IO NS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 5.1 QU AN1TTATIVE FAU N AL STUDIES . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 5.2 QUAN1TTATIVE ALGAL COMMUNITY MONirORING .............. 29 5.3 QU ALITATIVE TRANSECT SURVEYS . . . . . . . . . . . . . . . . . . . . . . . . . . 30 6.0 LITERATURE CirED .......................................... 31 1 LIST OF TAllLES Table 1. Algal Community Overlap in Percent Between Station Pairs for the Period 1983 1990
. ...................................................... 19 i
1.lST OF FIGUR13 L Figure 1. location of Rocky Point, limuent, ard Manomet Point Subtidal (10 ft MLW) Statiam . .
......................................................... 6 I
L Figure 2. Monthly PNPS Capacity Factor (vertical lines) arxl Circulating Pump Activity (tilack bars at 100% = 2 pumps; at 50% = 1 pump; at 0% = 0 pumps) Plotted for the Perkxl 1983 nm,ughi989 .. .......................................... .. 8 p l'igure 3. Species Richness for the Permd April 1983 'through September 1990 Plottal with Monthly PNPS Capacity Factor (MDC) . . . . . . . . . . . . . . . . . . . . . . . . ............ 10 7 lB Figure 4. Total Faunal Deruities (irxlividuals per m2) for the Perkx! April 1983 *lhrough September 1990 Plotted with the Monthly PNPS Capacity Factor (MDC) ......,.......... 12 Figurc 5. Total Faunal Demities, excluding Mytilus edults (lixtividuals per m2), for the Perkd April 1983 *lhrough September 1990 Plotted with the Monthly PNPS Capacity Factor (MDC) . 13 g Figure 6. Shanrum Wiener Diversity (H') Irxlex for Data liscluding Mytllus edults for the Perkxl l April 1983 'Ihrough 1990 Plotted with the Monthly PNPS Capacity Factor (MDC) .... 15 Figure 7. Dendrogram Showing Results of Cluster Analysis of Data Using N!!SS Similarity arxl I Group Average Sorting, Replicates Separate. A, April 1990; II, September 1990 . . . . . 16 Figure 8. Seasonal 11uctuatiom in Total Mean Algal llioman at the Manomet Point, Rocky Point, i arxl limuent Stations During Spring arxl Fall Sampling Periods for the Collections IMween April 1983 and Smtember 1990 Plotted with the Monthly PNPS Capacity Factor (MDC) . 21 Figure 9. Seasonal Fluctuations in Total Mean Phyllophora lilomass at the Marmmd Point. Rocky Point, arxl limuent Stations During Spring and Fall Sampling Periods for the Collections 11etween April 1983 and September 1990 Plotted with the Monthly PNPS Capacity Factor ( M DC) . . . . . . . . . . . . . . . . . . . . . . . . . . ......................... 22 Figure 10. Seasonal Fluctuatiom in Total Mean Omndrus Iliomass at the Manomd Point, Rocky I ?olnt, and limuent Statiom During Spring and Fall Sampling Periods for the Collections 11ctween April 1983 arxl September 1990 Plotted with the Monthly PNPS Capacity Factor (MDC).................................................... 23 Figure i1. Area of the Denuded arx! Stuntal Ames in the Vicinity of the PNPS limucnt Canal Plotted with the Monthly PNPS Capacity Factor (MDC). No area measurements were made in September arx! December 1987,1988, arx! March and June 1989 because of lack of dermitive demarcatiom of denuded and stunted runes . . . . . . . . . . . . . . . . . . . . . . . 26 Figure 12. Results of the 1990 Qualitative Tramect Surveys of the PNPS Acute impact Wme off the Discharge Canal. A, April; II, June; C, September; D, December .............. 28 il
I EXECUTIVE
SUMMARY
This volume of the semiannual report summarizes the potential impacts caused by the PNPS on the benthic communities in the vicinity of the Pilgrim Nuclear Power Station. Field and laboratory studies are detailed in volume 1 of this report. The cooling water that circulates through the plant is warmed and discharged through a canal into the nearshore waters of Cape Cod Bay. This discharged water includes two sources of potential impact on the benthic communities: 1) warming of ambient waters and,2) increased current velocities resulting in scouring of the bottom. Species composition and community structure may be potentially changed to varying degrees depending upon season and local oceanographic conditions. Scouring has a direct physical impact that actually removes benthic organisms and prevents recolonization, in its extreme, the bottom scouting results in rock surfaces that are completely denuded and devoid of marine life. The following observations were recorded as part of the 1990 benthic monitoring program. Total number of species observed at the Ef0uent Station are not directly related to plant operation, but may be related to habitat modi 0 cation caused by changes in mussel populations. Total faunal density Ductuations are strongly in0uenced by mussel populations. Unusually high mussel populations were observed in the vicinity of the discharge canal in June 1990. Mussels may have migrated to the site in response to higher temperatures from the themal discharge or by the currents. Species diversities declined at all stations in 1990, precluding any obvio is effects of PNPS on area wide I species diversity patterns. Community analysis using cluster analysis indicates that the by September 1990, the Ef0uent I Station differed structurally from the two reference stations. Two species, one anemone and an amphipod, were dominant at the Ef0uent station, but rare or absent at the other two stations. A composite assessment of all benthic community parameters including species richness, diversity, and density taken together with community composition indicates that subtle alterations in these parameters in the Ef0uent area are probably the result of PNPS operation, The algal community at the Ef0uent station was different from those at the Manomet Point and Rocky Point stations in 1990. The warm water alga, Gracilaria Ilkvahtae, was observed at the Ef0uent station during the April, June and December surveys (its absence in Septemb:r might be correlated with the low operating capacity of PNPS that month). In 1990, the number of algal species shared (overlap) between the reference stations was higher than between the Ef0uent and reference stations. This was a return to the pattern seen from 1983 to I ' I
I 1987. Algal blomass generally showed the same seasonal pattern observed since 1983 (except for 1986) only at the reference stations. Total mean algal biomass was lower in the spring than in the fall at Manomet Point and Rocky Point but declined from spring to fall at the Ef0uent Station. The size of the denuded Lone of the acute impact area in June and September 1990 was the largest observed since at least 1983. Area of the denuded zone is mainly in0uenced by circulating water pump operation but high pump capacity in 1990 does not alone explain why the denuded rone in 1990 is so much larger than that seen in 1983 and 1985 when the water pumps worked at 100% capacity. The large denuded area resulted from an anomalous increase that occurred between the April and June surveys. Typically, the denudal zone decreases in area during the spring, a time of abundant algal growth. I l I I I I I I I I I I l I ! l
I
1.0 INTRODUCTION
The benthic monitoring program at the Pilgrim Nuclear Power Station (PNPS) began in 1972, and has extended in various forms and at different levels to the present time; it was continued in 1990 under DECO Purchase Order 67621. The objectives of the program are to identify and assess any impacts of the operation of PNPS on the nearshore marine benthic communities. ~lle benthic communities are an excellent indicator of environmental perturbations because most of the organisms are unable to migrate away from sources of d!sturbance. Significant changes in benthic community parameters, therefore, can be correlated with the source of the perturbation. PNPS is a base load, nuclear-powered electrical generating unit designed to produce 670 megawatts of energy under full operational conditions. The station is cooled by water that is withdrawn from Cape Cod Bay. The cooling water is then returned to the Bay via a discharge canal that is designed to dissipate the heat from the water through rapid mixing and dilution. The two circulating pumps produce a combined water flow of approximately 20 m' per see at full operational capacity. The cooling system at PNPS includes two sources of potential impact on the benthic communities: 1) warming of I ambient waters and,2) increased current velocities resulting in scouting of the bottom. The Orst impact has the potential to stress the communities so that species composition and community structure are I changed to varying degrees depending upon season of the year and the in0uence oflocal oceanographic conditions. He second effect has a direct physical impact that actually removes benthic organisms and I prevents recolonization. In its extreme, the bottom scouring results in rock surfaces that are completely denuded and devold of macroscopic marine life. g 3 Operational conditions at the PNPS have provided an opportunity to assess long term trends associated with the impact on the benthic communities. Plant operations have included years of nearly full operation as well as times when there were complete shutdowns, sometimes for prolonged periods. The most recent shutdown began in April 1986 and extended until March 1989. This outage proved to be the longest shutdown in the history of plant. During this period the benthic communities associated with the ef0uent canal and areas immediately offshore received mainly reduced flows when a single circulating pump operated. No thermally enriched water was discharged. As a consequence, the benthic communities normally impacted by the ef0uent recovered to such an extent that by 1988 there was essentially no difference between the control locations and the areas near the discharge canal. Studies conducted in 1989 and 1990, therefore, were timed to assess the impact of plant operation on a benthic environment that had returned to near ambient conditions. I I
I This volume of the Semi Annual Report summarlies impact findings in relation to the benthic monitoring program. It discusses overall trends in the data presented in Volume I and in previous years' (19831989) reports in an effort to summarire the effects associated with PNPS operations on benthic communities. Volume 2 places particular emphasis on the effects of high plant operation following the long shut-down perkvJ outlined above. l 1 Il I IH I I I I l I 1 I I I t 4 g I
' -- ~
I 2.0 Mfiril0DS The present design of the benthic monitoring program includes quantitative and qualitative approaches for determining the presence and extent ofimpacts assoelated with the PNPS. Speci0 cations for methods and procedures follow guidelines established by the Pilgrim Administrative Technical Committee (PATC) and adopted by BECO as modined in 1981 (DECO,1987). The quantitative studies l were designed in order to compare benthic community parameters at three stations: 1) a surveillance station located approximately 120 m offshore from the mouth of the discharge canal (Efduent station),
- 2) a control or reference station located 0.25 nmi NW of the discharge canal (Rocky Point station), and
- 3) a reference station located 2 nmi SE of the discharge canal (Manomet Point station)(Figure 1). Algal and faunal community analyses performed on data collected from these stations are compared for spatial and temporal (seasonal) variability. Differences between the Ef0uent and reference stations are then examined for potential impacts associated with PNPS operation.
The Efouent station is located far enough offshore of the discharge canal that the most extreme scouring effects present in the discharge canal are moderated by wave action and long shore currents. The site, therefore, is believed to experience only subtle effects on community structure and species I composition, in contrast, the area in the near field discharge ef0uent itself is heavily impacted with considerable bottom scouring as evidenced by the algal denuded zone. In order to study this acutely impacted area, a qualitative diver transect study has been designed to map the affe:ts on algal I communities. Divers perform quarterly transect surveys to measure the extent of denudation and stunting of the algal flora in the discharge ef0uent plume. The focus of these studies is the commercially I important red alga, Chondrus crispus, a species common throughout western Cape Cod Bay. Divers swim along a measured transect line in the discharge ef0uent, noting the boundaries of the denuded, stunted, and normal Chondrus zones. Variations in the size of these zones are recorded over time as a means of determining the area most severely affected by PNPS operations. Detailed descriptions of field methodologies are present%I in the first volume of this report. I I I I
l 1
.,4. - .
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I 3,0 !!ACKGROUND PNPS operational conditions from 1983 through 1990 provide an opportunity to assess the degree of impact of the cooling water discharge on the benthic ommunities and on the length of time it takes for these communities to recover when the plant is shut down. Figure 2 depicts the annual maximum dependable capacity (htDC) factor and circulating water pump operation for l'NPS since 1983 The h1DC is a measure of reactor output that approximates thermal loading to the marine environment A maximum MDC value of 100% represents the highest allowable change in ambient temperature for water l discharge to Cape Cod Bay (18'C AT). The cumulative capacity factor from 1973 to 1990 was 46,8%, but from 1983 to 1990 was only 35.4%. During the life of the plent, power output has varied greatly The most productive years were 1979 (82.5%),1983 (80.3%),1985 (84.4%), and 1990 (72,3%). These very productive years have frequently been followed by low output years, with the most extensive period of non-output lasting f om April 1986 to March 1989. During times of plant shutdown or variable power outputs, only one or none of the circulating purnps may have been operating (Figure 2). During the shutdown that began in April 1986, one circulating pump was operational most of the time, but there were extended periods when no pumps were operated at all. The longest power outage ended in March 1989 with the resumption of electrical generation and I the operation of both circulating pumps. The high MDC percentage (72,3%) and the operation of both circulating pumps in 1990 has provided an opportunity to evaluate the effect of full plant operation on I benthic communities that had returned to ambient conditions following nearly three years of shutdown. I I I I I l ' I
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I 4.0 IMPACT 4.1 OUANTirATIVE FAUNAL COMMUNirY STUDiliS 4.L1 Species Rictmess The nr.mber of species collected at each station has been plotted over time as a measure oflong-term tr: des richness patterns (Figure 3). In terms of potential impact from the effluent discharged from PNPS, one obvious effect should be a reduction in numbers of species at the Efnuent Station during times of plant operation. At the same time, the numbers of species at the reference stations should remain consistently higher. Until 1987, this pattern was typleally observed during periods when the operation l of the plant was high. Ilowever, during the extended power outage, especially from March 1987 to September 1988, the Ef0uent station still exhibited lower numbers of species. Following this period, the l j number of species at the Ef0uent station increased and all three stations were essentially the same. By I the fall of 1990, the numbers of species at the Ef0uent station had again been reduced in relation to the 4 two reference stations. These long-term results suggest that the numbers of species present at the Effluent station are not necessarily related to the operation of the PNPS. One very obvious correlation between the long term trends in numbers of species is with the density of the blue mussel, Mytilus edulls. During 1987, mussel populations were very low at all stations, then gradually increased to unusually high population levels in September 1988 (see below for qualitative observations on dense mussel populations in June 1990), This i result correlates very well with the low counts of species at all stations that were observed in March 1987 and highs recorded in September 1988. It is likely that the mussels themselves caused sufncient habitat modification to establish additional niches that attracted a higher number of species. I Although mussel density can account for the higher number of species at a station, it does not account for lower absolute numbers of species at the Effluent station in relation to the reference stations. I This relationship is likely due to either subtle effects of the PNPS operation or to natural differences between the three stations. There have been examples of the reference stations themselves exhibiting as great a difference between them as with the Ef0uent station. I-I l I ' 1g
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4.1.2 Species Density l The total faunal densities from 1983 through 1990 are shown at all three stations (Figure 4). Total densities have fluctuated widely during this interval, largely because of periodic mass settlements of the blue mussel, Afytilus edulls. When mussels are removed from the density tabulations, total i densities are typically much lower (Figure 5). There does not appear to be any seasonal correlation with total density at any station. Long-term variation in individual species other than rnussels have not been investigated.' The biology of Mytllus edulls includes initiallarval settlement on filamentous red algae followed, , after a period of growth and development, by movement to sites of final attachment. The immigration of these " plantigrade" juveniles is probably more important than the inillal settlement and may explain the unusually dense populations that were observed in the efuuent canal in June 1990 as part of the qualitative transect surveys. The mussels were mostly small, but were observed to be so thick that the algae were completely buried by the masses of mussels. This population had been considerably reduced in September and was completely gone in December. This reduction in mussel population may have been I the result of predation by starfish, many individuals of which were observed to be associated with the mussels in June. Densities of Af edulls comparable to that in the discharge canal were not observed in adjacent I areas in June 1990. It is likely that the plantigrades moved to the site in response to some environmental cue. This cue could have been the higher temperatures caused by the ef0uent, and/or the more rapid I water movement caused by the current moving through the discharge area. i Historically, mussel populations at the Ef0uent station have been both higher and lower than the reference stations at Manomet Point and Rocky Point. No consistent pattern can be discerned from the data. 4.1.3 Species Diversity Species diversity is a measure of the relationship between the number of species (richness) and their abundance (density)in the community. Species diversity has been calculated in this program both with mussels included and excluded because their high numbers may obscure potential patterns. Two measures of diversity have been presented in the BECO reports. The first is the Shannon-Wiener (H') i 1 --,_r,__....__....... I1 I
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I index, with its associated evenness (Pielou's j'), and the second is Hurlbert's ratefaction values (See volume I for details). Long term summaries of H' values are provided in Figure 6. Typically, a seasonal pattern is evident, where low diversity values in the spring are followed by higher values in the fall. This pattern was observed, with few exceptions, more or less regularly from 1983 through 1989. In the 1990 samples, however, species diversity lacreased at both Manomet Point and Rocky Point between spring and fall, but decreased at the Ef0uent station overall. This latter result corresponds with a decrease in the total number of species at the same station (see above). Total density was lower at the Ef0uent station than at the two reference stations during both of these sampling periods. Overall, species diversities were lower at all three stations than in recent years. This appears to be a regional effect rather than any substantial impact caused by the PNPS. 3.1.4 Similarity Among Stations Cluster analysis was used to compare the community structure of each of the stations between seasons for 1990 (Figure 7). In the spring, the three stations were more or less indistinguishable from one another in terms of Bray Curtis and NESS similarity, llowever, the Ef0uent station replicates were joined to the Rocky Point and Manomet Point stations at a 0.55 level of NESS similarity in the fall which indicated that the Ef0uent station differed in species compositio.) from the reference stations. We have already noted how species diversity and the numbers of species were also lower at the Ef0uent station than at the reference stations during the same period. Analysis of the species composit!on data reveals that two species, the anemone, hietridium senile and the amphipod, Corophium tuberculatum, were dominants at the Ef0uent station in the fall, Aferridium senile was rare or absent at the other two stations and C. tuberculatum did not cccur at all at the reference locations. Another difference in species g composition that could have contributed to the different clustedng patterns between the spring and fall e data, was that the amphipod Jassafalcata was 5 to 10 times more abundant at the Ef0uent station in the fall than at the reference stations. These results indicate that the Ef0uent station was different from the reference stations in several of the benthic parameters. I I I l
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, I 4.1.5 Discus.sion-Faunal Studies Results of the quantitative benthic faunal studies revealed (nat by the end of 1990, the Ef0uent station differed structurally from the reference stations. These differenees included traditional benthic community parameters, such rs species diversity and density, as well as overall community composition as revealed by cluster analysis. Further inspection of the data indicated that in September two species had become dominant at the Efnuent station that were either not important or entirely absent at the reference stations. These species included the anemone, Afctridium scnlle and the amphipod, Corophium tuberculatum. The increase in Af. 3rnfle indicates that spaces on the rocks for development of populations of this anemone were suf0clent at the Efnuent station, but not at the reference locations. This result correlates to some extent with the mussel density that was considerably higher at the reference locations. Because mussels and anemones both require attachment surfaces, the lower mussel densities at the Ef0uent station might account for the increase in anemones. The results of the 1990 benthic community studies differed from those of 1989 in that the Ef0uent station actually became different in several aspects from the reference stations. In contrast,in 1989, there were only minor differences among the three stations. During 1989, richness and diversity were not depressed at the Ef0uent station, whereas these parameters were depressed in 1990. Likewise, there were no unusual species that were only limited to any one station, whereas an anemone and amphipod were dominants at the Efnuent station in the fall that were not important at the reference stations. These results suggest that after a full year of renewed plant operation, some changes began to emerge in the I structure of benthic communities near the discharge canal. No one single benthic parameter can be cited as evidence of PNPS having an impact on benthic communities at thesampling stations, but when all are I taken together, a cumulative impact is evident. Faunal communitics that are associated with thermal discharges and under some stress, are suspected to be characterized by low densities, few species, and elevated diversities (Logan and Maurer, 1975). Species that dominate in such an environment tend to be opportunists or pioneers. At the Pilgrim Station, benthic communities as topresented by the Ef0uent station located offshore of the discharge canal do not appear to be subjected to extreme stress, although low levels of potential stress were apparently present in September, as evidenced by depressed density, diversity, and richness. The Efnuent station differed structurally as evidenced by the Ef0uent station being dissimilar to the reference stations in the cluster analysis. The communities within the near field discharge ef0uent and qualitative survey area are more directly impacted by the bottom scouring and thermal discharge in that rock surfaces are denuded of their algal cover. Although quantitative benthic samples are not taken within the near Beld discharge g I
I ef0uent, logic would dictate that all community parameters would be drastleally reduced by loss of cryptic habitat. Ii f.2 OUANTTTATIVE ALGAL COMMUNrrY STUDIES 4.2.1 Algal Community Descriptions l The algal community at the Effluent station is dominated by the red macroalgae, Chondrus crispus and Phyllophora spp.. These species are also dominant at the Manomet Point and Rocky Point stations. Less abundant but nonetheless important algal speeles are those that indicate an effect upon the community by the thermal ef0uent of PNPS. These important species include Gracilaria tikvahlae, a warm-water species (BECO,1982), and Laminaria spp., a typical cold water alga, prevalent along the northeast coast of the United States. Gracilarla tibuhlac does not occur at the reference stations but occurred regularly at the Efauent station during normal operational years of PNPS. Gractlarla tibuhlac decreased drastically in abundance during 1986 and was entirely absent from the denuded zone during 1987, the second year of the three-year power outage. Conversely, Laminarla spp. was present within the area that had formerly been the acute impact zone during all four observation periods in 1987, 1988, and in March and June of 1989. The disappearance of Laminarla spp. by September 1989 and the reappearance of Gracilaria tibuhlar coincided with the return of PNPS to operational status. During 1990, G, tlkvahlae was observed in the impact zone of the Ef0uent station in April, June and December; lominarla spp. was only ol~rved and collected at the reference stations. 4.2.2 Algal Community Overlap Table 1 presents algal community overlap values (i.e., the percentage of shared species) between pairs of stations from 1983 through 1990. In general, the Manomet Point and Rocky Point stations have g been more similar to each other (higher percentage overlap) than either have been to the Effluent station, E and this pattern continued for the April and September 1990 collections. As in previous years, Qe g overlap values for the various station pairs (Manomet Point vs. Rocky Point, M anomet Point vs. Effluent, B and Rocky Point vs. Effluent) were not very different; the April and September overlap values had ranges of 7.4% and 11.4, respectively. The 1990 ;amples were unusual in that the species overlap between the reference stations was the highest recorded since 1983 in both April and September. I 18 s
I Table 1. Algal Community Overlap in Percent Between Station Pairs for the Period 1983-1990. I Overlap (%) Ycar Season MP vs. RP MP vs. EIT2 RPvs.EIT I Spring 81.0 85.2 81.0 I 1983 Fall 77.8 67.9 73.0 I 1984 spring Fall 76 0 84.0 68.0 73.1 70.4 71.0 Spring 8:. 0 77.0 75.0 1985 Fall 65.5 73.1 88.9 Spring 90.9 76.9 80.8 1986 Fall 84.0 70.4 77.8 Spring 77.2 66.7 70.8 I 1987 Fall 80.0 80.0 76.0 Spring 88.9 81.5 82.5 I 1988 Fall 82.8 89.7 85.7 I 1989 Spring Fall 81.5 87.0 76.9 85.2 80.0 74.1 Spring 96.3 88.9 92.6 1990 Fall 96.0 80.8 84.6 I I I
- I
. I " !I l
I The small range in overlap values seen for most sampling periods indicates a relatively homogeneous algal species distribution among all three stations. Only twice, since 1983, hr.ve the reference stations shared fewer species with each other than one of them with the Efnuent station. Such variations in species overlap are not necessarily directly caused by effects related to PNPS operations, but rather are part of naturally occurring, seasonal and long term variations in Cape Cod Day (BECO, 1989). In addition, the nearly 3 year power shutdown of PNPS from April 1986 until hiarch 1989 did not cause any marked changes in the dominant algal species composition, indicating that PNPS operations have had little effect on species composition. Since the plant has resumed operation, overlap between all three station pairs has been very high and the overlap values for 1990 were consistently higher than those seen in 1989. 4.2.3 Algal Biomass I' The April 1990 samples showed that algal biomass failed to follow the typical seasonal decline ; through the winter months. Rather, at all three stations the mean values for total algal biomass increased from September 1989 to April 1990 (Figure 8). During the summer of 1990, total algal biomass increased at hianomet Point and Rocky Point, as expected, but decreased sharply at the Ef0uent station, to the second lowest value seen since 1983 (lowest value occurred in hf arch 1989). The summer increase in biomass at the reference stations was mostly due to an increase in Phyllophora spp. biomass (Figure 9). In contrast to the increase in Phyllophora spp. from spring to fall, the biomass of Chondrus decreased at all three stations, most precipitously at the Effluent station (Figure 10). Chondrus biomass at the Effluent station in September 1990 was the lowest recorded since 1983. 4.2.4 Discussion- AI Eal $tudies By the end of 1990, PNPS had been in operation for nearly two years, and the Ef0uent station showed effects caused by the cooling water discharge that were similar to those seen during previous times of peak power generation at the plant. The results of algal community studies performed in 1990 show that the Effluent station differed from the reference stations in species composition, supporting a similar conclusion from the faunal studies. hieasures of similarity between station pairs (Jaccard's coefficient of community) show a greater degree of similarity between the reference stations than between I 20 I
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100 to o isi iiiiiii iiiiiiii1( isiiiiiii isiisiiiiiissiieiiinisaisisiiisisiiiiiiiisii iiiaiiiiisiii. ii ; o u s s o u s s o u s s o u s s o u s s o u s s o u s s o u s s o 1983 1984 1985 1986 1987 1988 1989 1990 l A Emuent CJ Manomet Point .M Tbcity Point MDC n. Figure R. Seasonal Fluctuations in Total Mean Mgal Biomass at the Manomet hiint, Rocky Point, and Efiluent Statiotts During Spring and Fall Sampling Periods for the Collections Between April 1983 and September 1990 Plotted with the Monthly PNPS Capacity Factor (MDC). l l
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3 o i o n o o n o o o n o i n o o n n o t iWoJn 5o D. rrru M n nJ o5o 0n .uoJi n5 o0o o oW oJ n$ . Do Mn o n nJi .5o n DlM J 5 9 W J 5 0 D u J $ D 1988 1989 1990 1985 1985 1987 1983 1984 C) Manomet Point 3*E NGy Point MDC A Emueit Figure 9. Seasonal Flunnitions in Total Mean Inyllor n ora Biomass at the Manomet Ibint Rocky Point, and Efiluent Stations During Spring and Fall Sampling Periods for the CoIIections Between April 1983 and Sq0A 1990 f%tted with the Monthly P Capacity Factor (MDC). M M M E M M M M g 3 E E E E E E E E E
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I stations thrin between either reference station compared to the Efouent. This observation is typical for the study and for 1990 was caused, in part, by fewer species occurring at the Ef0uent station than at the reference stations during both sampling periods. During April, the cold water speeles leminarla spp. was absent only from benthic samples collected at the Ef0uent station and, in September, three species of secondary algae that occurred at both reference stations were absent from the Ef0uent. The effect of power plant operation upon the algal cormuunity has been confined primarily to chanEcs in species composition rather than biomass. This pattern was repeated in the 1990 samples. 131omass values for the major algal categories failed to shew any differences among stations for either season that would indicate a significant effect of PNPS at to Efauent (Figures 810). The impact of PNPS on the algal community of the Ef0uent station is tc0ceted in the presence or absence of several less dominant species, probably because of differences in ecological requirements of the different species. For example, the warm water species Gracilarla Ilhuhlae is found only at the Ef0uent station during times of thermal discharge and the cold water species lemInaria spp is found only at the reference stations. I I I I I I l I I , I 24 I
l 4.3 OUAlJTATIVE'UMNSECESURyjiYS Reselts of the qualitative transeet !.urveys from 1983 through 1990 are presented in Figure 11). The total acute impact area (denuded and stunted)is plotted with the extent of the denuded zone alone and the monthly PNPS capacity factor (hlDC). The difference between the denuded and total acute impact zones represents the stunted zone. A lag-time in recovery response by the acute impact rone to the 1984 PNPS power outage was reported in Semi Annual Report No. 27 (BECO,1986). Evidence of tHs slow recovery included a decrease in the area of the total acute impact zone that began in mid 1984 (5 months after the cessation of power plant operations) and continued through mid 1985. Between December 1984 and December 1985, the total impacted area (denuded and stunted zones combined) was the smallest recorded between 1983 and 1986, indicating a delay in recovery of this area in response to the absence of thermal discharge in 1984. This phenomenon reversed itself under normal PNPS operating conditions, so that only 6 to 9 months after the resumption of thermal efnuent discharge the size of the acute impact rone began to increase between September and December 1985). These results conGrmed a delay period of about 6-9 months between the causal factor (cessation or resumption of thermal efnuent discharge) and associated response (decrease or increase of the acute impact zone size). From 1987, increased recolonization of the denuded and stunted zones by Chondrus crispus made zone boundaries difficult to distinguish (no areal differences could be discerned from September 1987 through June 1989). As in summer 1984, the considerable decrease of the denuded area of the acute I impact zone from December 1986 to June 1987 was mostly the result of the shutdown of the circulating we.ter pumps from late hiarcr. to early September (DECO,1988). Apparently, water current scouting I is a greater stress to algal colonization than increased water temperature. Scouring denudes the substratum, whereas elevated temperature results in stunted growth (Bridges and Anderson,1984), I in 1988, the circulating water pump activity was low, resulting in little thermal loading and scouting effect. Results of the 1988 transect survey showed increased recolonization of the formerly I denuded and stunted zones by CAondrus in response to the continuing outage. Divers were unable to detect boundaries of these zones and no area measurements could be made. I I 25 I
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L in March and June 1989, divers were again unable to detect boundaries of the denuded or stunted zones and no area measurements were made (BECO,1990). In September and December, presumably in response to increased PNPS operations and the resultant scouring of the acute impact zone, boundaries t.egan to be redefined and area measurements could be made of the total impact zone. During 1990, the boundaries between the stunted and denuded zone became more clearly defined and areal measurements of both zones continued (Figure 12). The areas of the denuded and total acute impact zones in June were the highest seen since 1983. The dramatic increase in total affected area that lb occurred between April and June 1990 has not been seen before in the 1983-1990 period. The typical pattern seen in 1983 and 19851987 is that during the spring, with warmer temperature and increased sunlight, algal growth flourishes and the impact area declines even in years with high power plant operating capacity. The pattern son in 1990 is anomalous and permits no ready explanation. I I I I I I I i l i
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om ~~s soum um ~~= soum I Figure 12. Results of the 1990 Qualitative Transect Surveys of the PNPS Acute Impact Zone off the Discharge Canal. A, April; B, June; C, September; D, December. 28 5_
5.0 CONCLUSION
S 5.1 OUANTITATIVE FAUNAL STUDIES e Total number of species observed at the Ef0uent Station are not directly related I to plant operation, but may be related to habitat modincation caused by changes in mussel populations.
- Total density fluctuations are strongly influenced by mussel populations.
I. Unusually high mussel populations were observed in the vicinity of the discharge canal in June 1990. Mussels may have moved to the site in response to higher temperatures from the thermal discharge or to the discharge currents.
- Species diversities declined at all stations in 1990, precluding any obvious effects of PNPS on area wide species diversity patterns.
- Community analysis using cluster analysis indicates that by September 1990, the l Effluent station differed structurally from the two reference stations. Two species, one anemone and an amphipod, were dominant at the Effluent station, l but rare or absent elsewhere, j
- A composite assessment of all benthic community parameters including species richness, diversity, and density taken together with community composition indicates that subtle alteracons in the Effluent station are probably the result of PNPS operation.
5.2 OUANTITATIVE ALGAL COMMUNITY MONITORING
- The algal community at the Efiluent station was different from those at the Manomet Point and Rocky Point stations in 1990. The warm-water alga,
.E Grac!/ aria tlkvahlae, was observed only at the Eftluent station during the April, 5 June and December surveys (its absence in September might be correlated with the low operating capacity of PNPS that month).
- In 1990, the number of algal species shared (overlap) between the reference stations was higher than between the Effluent and reference stations. This was a return to the pattern seen from 1983 to 1987.
- Algal biomass generally showed the same seasonal pattern observed since 1983 (except for 1986) only at the reference stations. Total mean algal biomass I increased from spring to fall at Manomet Point and Rocky Point but declined from spring to fall at the Effluent Station.
I I I 29 E l 4
I 5.3 OUALITATIVE TRANSECT SURVEYS
- The size of the denuded zone of the acute impact area in June and September 1990 was 3 the largest observed since 1983. Area of the denuded zone is mainly influenced by 5 circulating water pump operation, but high pump capacity in 1990 does not alone explain why the denuded zone in 1990 is so much larger than that seen in 1983 and 1985 when 3 the water pumps worked at 100% capacity. The large denuded area resulted from an 5 anomalous increase that occurred between the April and June surveys. Typleally, the denuded zone decreases in area during the spring, a time of abundant algal growe.
There is no apparent explanation for this anomalous pattern. I I I I I I I I I I I I 30 a_
I 6.0 LITERATURE CITED Boston Edison Co 1982, hiarine ecology studies related to operation of Pilgrim Station. Semi Annual Report no.19. Boston hia. I Boston Edison Co.1986 hiarine ecology studies related to operation of Pilgrim Station. Semi-Annual Report no. 27. Boston hia. Boston Edison Co.1987. Marine ecology studies related to operation of Pilgrim Station. Semi-Annual Report no. 29. Bostoa hia. Boston Edison Co.1988 hiarine ecology studies related to operation of Pilgrim Station. Semi Annual Report no. 31. Boston hia. Boston Edison Co.1989, hiarine ecology studies related to operation of Pilgrim Station. Semi-Annual Report no. 33. Boston hia. Boston Edison Co.1990, hiarine ecology studies related to operation of Pilgrim Station. Semi Annual Report no. 35. Boston hia. Bridges, W. L. and R. D. Anderson,1984. A brief survey of Pilgrim Nuclear Power Station hiarine Ecology Study Program. Lecture Notes on Coastal and Estuarine Studies 11:263 271. Logan, D.T. and D. hiaurer. 1975. Diversity of marine invertebrates in a thermal effluent. Journal of I the Water Pollution Control Federation 47:515-523. I I I I I I 31 I
I l k ICHTHYOPLANKTON ENTRAINMENT MONITORING AT PILGRIM NUCLEAR POWER STATION JANUARY-DECEMBER 1990 Volume 1 of 2 (Results) I I Submitted to Boston Edison Company I I- by Marine Research, Inc. ral - th, Massachusetts I April 1, 1991 I I I I I I
iE !I I TABLE OF CONTENTS SECTION PAGE n EXECUTIVE
SUMMARY
1 i' I l II INTRODUCTION 2 4 III METHODS AND MATERIALS 3 ( lg 13 RESULTS AND DISCUSSION 7
- IV A. Ichthyoplankton Entrained - 1990 7 f
i i B. Multi-year Ichthyoplankton Comparisons 14 C. Lobster Larvae Entrained 27 1 V HIGHLIGHTS 29 j3 1 g lI i i APPENDICES A and B (available upon request) I , 1 I I g ! l I I 1 I 5 1
LIST OF FIGURES u- enan
] 1 Entrainment sampling station in PNPS discharge j canal. 4 2 Location of entrainment contingency plan samp-ling stations, C-1 through C-13. 6 Dominant species of fish eggs and larvae found 3
l in PNPS ichthyoplankton samples by season. Per-l cent of total and summed monthly means for all species are also shown. B 4 Mean monthly densities per 100 m' of water in the PNPS discharge canal for the eight numer-ically dominant egg species and total eggs, 1990 (dashed line). Solid lines encompassing shaded area show high and low values over the 1975-1989 period. 16 5 Mean monthly densities per 100 m) of water in the PNPS discharge canal for the eleven numeri-cally dominant larval species and total larvae, 1990 (dashed line). Solid lines encompassing shaded area show high and low values over the 1975-1989 period. 20 LIST OF TABLES TABLE PAGE 1 Species of fish eggs (E) and larvae (L) ob-tained in ichthyoplankton collections from the Pilgrim Nuclear Power Station discharge canal, January-December 1990. 30 2 Species of fish eggs (E) and larvae (L) col-lected in the PNPS discharge canal, 1975-1990= 33 LIST OF APPENDICES APPENDIX Densities of fish eggs and larvae per 100 m8 of I A* water recorded in the PNPS discharge canal by species, date, and replicate, January-December 1990. B* Mean monthly densities and range per 100 m3 of water for the dominant species of fish eggs-and larvae entrained at PNPS, January-December 1975-1990.
*Available upon request.
11
SECTION I EXECUTIVE
SUMMARY
PNPS ichthyoplankton sampling was completed twice per month in January, February, October-December, weekly from April through September; while scheduled weekly in March, sampling was possible only twice due to equipment failure. Numerical dominants among the 42 species represented in the 1990 collections included sand lance, sculpin, and rock gunnel in winter-early spring; Atlantic mackerel, cunner, and fourbeard 3 rockling during late spring-early summer; and windowpane, cunner, rockling, and hake in late summer-autumn. Comparisons between 1990 monthly mean densities per 100 m) of water and those recorded over the 1975-1989 period suggest that Atlantic cod eggs and winter flounder larvae were comparatively uncommon in 1990. While fourbeard rockling eggs were common in April compared with past years, they were relatively uncommon in September. Atlantic mackerel eggs, Atlantic herring larvae, rockling ' larvae, tautog larvae, and cunner larvae were all relatively abundant in the 1990 collections. Two lobster larvae were found in the 1990 entrainment samples. These were the first to be recorded since 1982, bringing the total collected at PNPS to eleven in 17 years of sampling. 1
I SECTION II INTRODUCTION This report summarizes results of ichthyoplankton entrainment sampling conducted at the Pilgrim Nuclear Power Station (PNPS) discharge canal on a regular basis from January through December 1990. Work was carried out by Marine Research, Inc. (MRI) for Boston Edison Company (BECo) under Purchase Order No. 67253 in compliance with environmental monitoring and reporting requirements
- of the PNPS NPDES Permit (U.S. Environmental Protection Agency and Massachusetts Division of Water Pollution Control). In an effort to condense the volume of material presented in this report, details of interest to some readers may have been omitted. Any questions or requests for additional information may be directed to Marine Research, Inc., Falmouth, Massachusetts, through BECo.
I I I I I I I I E
I I SECTION III METHODS AND MATERIAI4 Entrainment sampling at PNPS was completed twice per month during January, February, October, November, December, and weekly April-September. Although weekly sampling was scheduled for March, j only two collections were made due to failure of the not rigging. ! Samples were collected in triplicate from rigging mounted approxi- i l mately 30 meters from the headwall of the discharge canal (Figure 1), at low tide during daylight hours. A 0.333-mm mesh, 60-cm diameter plankton net affixed to this rigging was streamed in the canal for 8 to 12 minutes depending on the abundance of plankton I and detritus. In each case, a minimum of 100 m2 of water was sampled. Exact filtration volumes were calculated using a General Oceanics Model 2030R digital flowmeter mounted in the mouth of the net. All samples were preserved in 10% Formalin-seawater solutions and returned to the laboratory for microscopic analysis. A detailed description of ~hec analytical procedures may-be found in MRI.(1988).* When the Cape Cod Bay ichthyoplankton study was completed in 1976, a contingency sampling plan was added to the entrainment monitoring program. This plan was designed to be implemented if eggs or larvae of any dominant species proved to be " unusually
- Marine Research, Inc. 1988. Ichthyoplankton Entrainment Monitor-ing at Pilgrim Nuclear Power Station January-December 1987.
III.C.1-6-10. In: Marine Ecology Studies Related to operation of Pilgrim Station. Semi-annual Report No. 31. Boston Edison Company.
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,1
I abundant" in the PNPS discharge samples. The goal of this sampling plan was to determine whether circumstances in the vicinity of Rocky Point, attributable to PNPS operation, were causing an abnormally large percentage of ichthyoplankton populations there to be entrained or, alternatively, whether high entrainment levels simply were a reflection of unusually high population levels in Cape Cod Bay. " Unusually abundant" was defined as any mean density, calculated over three replicates, which was found to be 50% greater than the highest mean density observed during the same month from 1975 through 1989. The contingency sampling plan consists of taking additional sets of triplicates from the PNPS discharge on subsequent dates to monitor the temporal extent of the unusual density. An optional offshore sampling regime was also established to study the spatial distribution of the species in question.. The offshore contingency program consists of single, oblique tows at each of 13 stations (Figure 2) on both rising and falling tides for a total of 26 samples. Any contingency sampling requires authorization from Boston Edison Company. I I I I I " I
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5 s ~ SECTlQH_lY l EESyLTS AND DISCUSSION A. Jphthvoplankton_ Entrained - 1990 Population densities per 100 m) of water for each species listed by date, station, and replicate are presented for 1990 in Appendix A (available upon request). Table 1 lists all species represented in the 1990 collections, indicates the months eggs and/or larvae of each species wore found and, for the more common species, the months of peak abundance. Ichthyoplankton collections are summarized below within the three primary spawning seasons observed in Cape Cod Bay: winter-I early spring, late spring-early summer, and late summer-autumn. Figure 3 shows the dominant species of eggs and larvao within each season for 1990. Winter-early sorina spawners (December-April) The beginning of this spawning season is sampled at the end of-the calendar year. Th' December 1990 collections consisted of a single lumpfish egg (Cyclooterus lumpus) and a small number of Atlantic herring larvae (Clunea harenaus harengus). The collections represented monthly mean densities of 0.1 per 100 m' for lumpfish eggs and 1.2 per 100 m8 for herring larvae. The number of species represented in the earlier collections of this season was five in January, three in February, seven in March, and 19 in April. Eggs remained 7
I I I I I I Figure 3. Dominant species of fish eggs and larvae found in PNPS ichthyoplankton samples by season. Percent of total 3 and summed monthly means for all 3 species are also shown. I I I I I I I I I I-I'
I I Eggs Larvae I Late Summer-Autumn Season Auguet-Hov.mb., Late Summer-Autumn Auguet Nov.mb., o~, wimsv p.w 3044 -
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I I I I I Figure 5. Mean monthly densities por 100 n8 of water in the PNPS discharge canal for 'che eleven g numerically dominant larval species and a total larvae, 1990 (dashed line). Solid lines encompassing shaded area show high and low values over the 1975-1989 period. Clupea harenaus hargamm Amadytes sp. Encholympus niinbrius Scomber scombrun Tautoca gnitis HYRXQEpohalug spp. Tautocolabrug adspersus Liparis spp. Ult' aria nubbif urcata Pseudocleuronectes americanug Pho11s gunnellus Total larvae I I I I I I
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i l MYOXOCEPHALUS SPP. LARVAE .i LIPARIS SPP, LARVAE f I i I! i 100 1000 j E
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t v. m c . s .2 v 34 l g r 3,.
r Mw r- r L_ J Table 2(continued). SMcies 1975 1976 1977 1978 1979 19E0 19?1 1022 IW3 loE4 IT5 1%6 IW7 IMS IM E IFJ Feriod ofJul 0_ w ir s
- Oct L E E/L E E_trp2tgejcrostatns L
L E/L E L Sep - RN [aialichthysdantatus E/L E/L E/L E/L E/L E/L EIL E/L E/L My - Cd E/L E/L E/L E/L E/L E/L E/L E.oblonTr* E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L ppr(my) - (M)frt Scephthales eg'rss* E/L E/L E/L E/L E/L E/L E/L E/L E E/L E/L E/L E/L E/L E/L mr(My) - (Jun))EN Glypto shaltn etnoclessus E/L E/L E/L E/L E/L E/L E/L Himlessoidq platessoidesE/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L Jan(Mr) - (Je)55 E E/L E/L E/L E/L E/L E/L Feb( Apr) - (Nyj%N L_iggnda larjn tna E/L E/L E/L E/L E/L E/L E/L E/L E/L L Nr-Jm Lippsvita pt:trani E/L E/L E/L E/L E/L E/L E/L E/L E/L Jat[ Apr) - (Jun)pa; (Mudafl eWas amricanu:;E/L E/L L E/L E/L E/L E/L E/L E E E E E/L E/L by - Sep E E Irinactes sculater L Jul - Ra; Spberroidas eaculattt; L 40 38 37 34 42 37 36 41 43 42 Ntr er of 5;&ias** 36 43 35 37 35 M 41 of larvsa.
'Altheuch those e7;s wre not identified s;eifically, tier wre asstrad to have occurred as sher: based en tha octurer, **For c:cparative purposes tre spacies of Myoxocerbalt::: wre asstred for 1975-I?78 and tio spacias of LDris fer I?75-1980.
l l l
I ,I I I I APPE!1 DIX A* I Densities of fish eggs and larvac per 100 m' of water recorded in the Pf1PS dis-I charge canal by species, date, and repli-cate, January-December 1990. I
*This Appendix is available upon request.
I I I I I I
'I I
I
m r APPENDIX B* Mean monthly densities and range per 100 m8 of water for the dominant speeles of fish eggs and larvio entrained at PNPS, I January-December, 1975-1990. l *This Appendix is available upon request. I I I
Y - Aupendiz_B l " Mean monthly densities and range per 100 m8 of water for the dominant species of fish eggs
~
and larvae entrained at PNPS, January-December 1975-1990. Some standardization of data sets was required to adjust for changes in the sampling program which have occurred over the years:
- 1. Only 0.333-mm mesh net data were used in those cases (1975) when field sampling was carried out using both 0.333 and 0.505 mesh nets.
- 2. When, as in 1976 and 1977, 24-hour sampling series were conducted, the samples taken nearest the time of daylight low tide were selected for comparison since this conforms to the routine specification for the time of entrainment sampling used in all subsequent years.
- 3. For the same reason only daylight low tide data were used When, in 1975, samples were also taken at high tide and/or at night.
I 4. Cod and pollock egg densities were summed to make up the category "gk2 Oc" since these eggs were not distinguished prior to 1976. In January and February when witch flounder do not spawn, all three egg stages are included in this estegory. During the remaining months early-stage eggs are included with the gadidae-Glvotocephalus group.
- 5. Beginning in April when the Enchelyocus-Urophycis-Esprilus grouping became necessary, the listing for Enchelyopus 1
I , cinbrius includes only late-stage eggs, the two early stages being included with the grouped eggs.
- 6. Since the Brosme-Scomber grouping was not considered necessary af ter 1983, grouped eggs were added to S. Ecombrun eggs in the table for 1975-1983 (D. brosme eggs having always been rare).
- 7. Sculpin larvae were identified to species beginning in 1979 following Khan (1971). They are shown by species beginning with that year as well as added together (Myoxocephalus spp.)
for comparison with prior years.
- 8. Similar results ar. shown for seasnail larvae which were not I speciated prior to 1981.
- 9. Although samples were in fact taken once in April 1976 and once in March and August 1977, comparisons with other years when sampling was weekly are not valid and corisequently do not appear in the table. Data collected in 1974 was not included because samples were not collected at low tide in all cases.
- 10. When extra sampling series were required under the contingency sampling regime, results were included in calculating monthly mean densities.
Table format: Mean Range I
+ Khan, N.Y. 1971. ComparatiNe morphology and ecology of the pelagic larvae of nine cottidae (Pisces) on the northwest Atlantic and'St. Lawrence drainage. Ph.D. thesis, University of Ottawa.
234p. l l
s F L E ICHTHYOPLANKTON ENTRAINMENT MONITORING AT PILGRIM NUCLEAR POWER STATION JANUARY-DECEMBER 1990 Volume 2 of 2 (Impact Perspective) I Submitted to Boston Edison Company Boston, Massachusetts I by Marine Research, Inc. Falmouth, Massachusetts April 1, 1991
e I TABLE OF CONTENTS SECTION EAqE I EXECUTIVE
SUMMARY
1 II INTRODUCTION 2 III IMPACT PERSPECTIVE A. Contingency Sampling Plan 3 B. Ichthyoplankton Entrainment - General 6 C. Ichthyoplankton Entrainment - Specific 7 D. Potential Pump Effects 11 E. Lobster Larvae 38
.I IV HIGHLIGHTS 20 V LITERATURE CITED 21 I
I I i I
I LIST OP FIGURES PIGURE 1%GE 1 Numbers of eggs estimated to have boon entrained by PNPS in 1990 had it operated at full pump flow I by species or species group (dominants only) in-cluding all egg species combined. The period of occurrence observed in 1990 is also indicated. 8 2 Numbers of larvae estimated to have been en-trained by PNPS in 1990 had it operated at full pump flow for each dominant species including all I larvae combined. The period of occurrence ob-served in 1990 is also indicated. 9 I 3 Hoan monthly densities per 100 m8 of water for total eggs and total larvae entrained at PHPS within four pump operation categories during I the April-August period of 1983-1990. Values for 1983,1985, 1990 are averaged (all pumps operating) as are 1986,1988 (1 CWS pump out of
. service). See text for details. 15 LIST OF TABLES TAllLE I 1 Ichthyoplankton densities por 100 m8 of water which reached the "unasually abundant" level in PHPS entrainment samples, 1980-1990. 4 LIST OF PLATES PLATE 1 Plankton not streaming in the discharge canal at Pilgrim Station for the collection of fish eggs and larvae (lobster larvae are also recorded).
I A single, six-minute collection can contain sev-eral thousand eggs and larvae representing 20 or more species. I I 11 I
s SECTION 1 EXECUTIVE
SUMMARY
Ichthyoplankton collections were made in the Pilgrim Nuclear Power Station (PNPS) discharge canal in triplierte twice por month in January and February, weekly from April thr, ugh September, and twice per month from October through December; although scheduled for weekly in March, sampling was possible only twice due to equipment failure. PNPS operated at 72% capacity in 1990, by far the highest level since 1985. Ichthyoplankton densities meeting the " unusually abundant" critorion defined under the congingency sampling program were not recorded in 1990. Based on full load flow capacity, total numbers of eggs which may have been entrained by PHPS in 1990 were estimated to range from 1.7 million for searobins to 1.9 billion for Atlantic mackerel, corresponding values for larvae ranged from 5.9 million for Atlantic herring to 134.8 million for cunner. Recent declines in abundance of cunner, windowpano, yellowtail flounder, and winter flounder in collections around PHPS appear to be widespread and therefore unlikely to be directly related to entrainment of eggs and larvae. Examination of egg and larval entrainment between years with differing pump regimes strongly suggests that larval entrainment and perhaps even egg entrainment are directly correlated with water usage rates. Although two larval lobsters were collected in PNPS entrain-ment samples in 1990, their overell scarcity at PNPS remains an interesting topic. 1
Il SECTION II INTRODUCTIO1{ , i This report addresses results of PHPS ichthyoplankton entrainment sampling in relation to potential impact assessment. Discussions are based on results presented in "Ichthyoplankton Entrainment Monitoring at Pilgrim Nuclear Power Station January-December 1990", Volume 1 - Results. Work was conducted by Marine Research, Inc. (MRI) for Boston Edison Company (BECo) under Purchase Order No. 67253 in compliance with environmental monitor-ing and reporting requirements of the PHPS NPDES Permit (U.S. Environmental Protection Agency and Massachusetts Division of Water Pollution Control). In a continuing effort to condense the volume of material presented in this and related reports, details of interest to some readers may have been omitted. Any questions or requests for additional information may be directed to Marine Research, Inc., Falmouth, Massachusetts, through BECO. Plate 1 shows the ichthyoplankton sampling net being deployed l on station in the PNPS discharge canal. I I I I l I \ l (
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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 le larvae representing 20 or more species, I E E E
^ - - ---- _ '%%%,_
I SECTION III IMPACT PERSPECTIVE A. Contingency sannling Pinn Ichthyoplankton densities in the PNPS discharge canal meeting the " unusually abundant" criterion, defined as exceeding by 50% the highest mean density over three replicates recorded during the same month from 3975 through 1989, did not occur in 1990. This compares with no occurrences in 1989, two occasions in 1988, no occurrences in 1987 or 1986, four in 1985, six in 1984, one in 1983, eight in 1982, seven in 1981, and twelve in 1980 (Table 1). No specific events were recorded prior to 1980 primarily because " unusually I abundant" was not precisely defined early in the contingency plan. In past years it was standard practice for BECO, in consulta-tion with regulatory personnel, to autt.orize 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 occurrence of a high-density ichthyoplankton patch in the Rocky Point area rather than a more widespread phenomenon. In the three cases where high densities persisted (larval Atlantic menhaden, Brevoortia tyrannus, June 1981; larval rock gunnel, Phglig gunnellus, April 1982; larval rock gunnel, February 1985, additional entrainment sampling at I I
I Table 1. Ichthyoplankton densities per 100 28 of rater which reached the
" unusually abundant"* 1evel in PNPS entrainment samples, 1980 1990.
" Unusually abundant" Previous high Snecies Month dgpsity (yeari density (yeari l
EGGS Brevoortin tyrannus June 74.2 (1980) 6.2 (1978) Se pt ember 1961.9 (1982) 1.4 (1979) gl 1065.8 (1982) gi October 37.8 (1980) 0.2 (1978) Enchelvoous Urochvcis September 71.3 (1980) 30.1 (1979) Peprilus Urochvcis spp. September 152.8 (1980) 22.3 (1978) Labrid Limanda 6 labrid July 12917.0 (1981) 8116.8 (1975) Scomber scombrus May 15261.3 (1985) 572.0 (1980) 1457.6 (1985) LARVAE Brevoortia tyrannus June 7.1 (1981) 4.2 (1980) 495.9 (1981) " 34.7 (1981) ! October 11.7 (1980) 1.8 (1976) November 24.3 (1980) 3.2 (1978) Enchelvoous cimbrius August 204.6 (1983) 36.0 (1980) Urophycis spp. September 105.6 (1984) 22.3 (1981) Tautogn onitis August 21.6 (1984) 4.1 (1974) September 9.2 (1980) 4.8 (1975) l Tautogolabrus adspersus June 624.5 (1981) 378.8 (1977) , July 296.5 (1980) 1 S.5 (1974) 2162.5 (1981) 296,5 (1980) g September 20.3 (1980) 1.5 (1975; g Pholis gtnnellus February 19.6 (1984) 7.4 (1975) ' 13.8 (1984) 47.5 (1985) 19.6 (1984) l March 70.2 (1980) 36.9 (1975) 210.5 (1984) 70.2 (1980) 3 415.2 (1984) " " 3 April 74.0 (1982) 12.1 (1977) 74.7 (1982) " " 34.0 (1982) " 22.4 (1982) " " 23.5 (1982) 4 a
I Table 1 (continued) .
" Unusually abundant" Previous high Specias Month density (yeari density (year)
I LARVAE (continued) Ammodvtes sp. January 31.1 (1980) 104.4 (1985) 13.5 (1975) 31.1 (1980) - scomber scombrus June 2700.0 (1981) 128.0 (19/5) Mvoxocechalus spp. February 79.2 (1988) 37.4 (1985) I March April 153.6 (1980) 308.3 (1988) 303.6 (1982) 97.0 (1975) 188.7 (1986) 53.1 (1981)
*" Unusually abundant" was defined as 50% greater than the presious high density I observed during the same month 1975 1989.
I I I I I I I I I I 5
I about two-day intervals indicated that high densities continued fo: up to two weeks. Since no changes in PNPS operation occurred, it appeared in those situations that productivity was generally high relative to previous years. B. Ichthyonlankton Entrainment - General Entrainment of-ichthyoplankton at PNPS represents a direct, negative environmental impact since fish eggs and larvaa pass through the plant in large numbers each day and are subjected to elevated temperatures, mechanical forces, and periodic chlorine-tion. When PNPS is not on line, increased temperature is not a factor but ichthyoplankton may still be subjected to mechanical forces and periodic chlorination when circulating seawater pumps operate. Although survival has been demonstrated for some species of fish eggs at PNPS such as the labrids (45%; Marine Research 1978, 1982) an6 among larvae at other power plants (0-100% initial survival depending on species and size; Ecological Analysts 1981), mortality is asnumed to be 100% as a conservative approach to PNPS impact assessment. To place fish egg and larval densities entrained . at PNPS, expressed as numbers per 100 m) of water, in some perspective in relation to amounts of water utilized by PNPS, they were multiplied by maximum plant flow rates over each respective period of occurrence. This was completed for each of the numerically dominant species as well as total eggs and total larvae. Mean
-monthly densities were multiplied by 17,461.44, the full load flow i
a_
I capacity of PNPS in 100 m8 units per 24-hour day, then by the number of days in each respective month they occurred. Values for each month 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 groups, numbers of eggs entrained ranged from 1,725,190 for searobins (Prionotus spp.) to 1,891,845,748 for Atlantic mackerel (Scomber I scombrus). Corresponding values among the eleven dominant larval l l l species ranged from 5,943,874 for Atlantic herrit.g (Clunea harengus harengus) to 134,802,317 for cunner (T.autogolabrus adsoersus) . For all eggs and all larvae combined values were 3,103,891,444 and 353,367,161, respectively. These numbers indicate the vast quantities of eggs and larvae which can be entrained by the circulating seawater system at PNPS during a year's time and presumably are lost to the local fish population. I C. Ichthvoplankton Entrainment - Specific The effects of entrainment on populations of Atlantic
' menhaden, winter flounder (Pseudooleuronectes americanus), pollock (Pollachius V.irfms) , cunner, rainbow smelt (Osmerus mordax),
Atlantic silversides (Monidia 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 appreciable adverse impact on indigenous pupulations. was predicted to occur. Modeling studies
- I lI
Number of Eggs Entrained - 1990 I SPECIES AND OCCURRENCE PERIOD i' 6.160.396 - !i1 l Brevoortia tyrannus (June-November) - l li ' 'l f ! ! Y' l Enchelyopus-Urophycis-Peprilus (April-October) - l 120.332.021 l 4 i Gadidae-Clyptocephalus (January-November) - f 2.615,724 , l l i i!-- Labridae-Limanda (May-October) - 1.008.934.226 l I c> Scomber scombros (May-September) - 1.891.84S 748 j Prionotus spp. (June-September) ] 1,725,190 Paralichthys-Scophthalmus (May-October) ~
- f. 60,919.472 Hippoglossoides platessoides (April-June) -
l 2.386.979 Total Eggs 3.103.891.444..- liti.,
,1 1 ,1, , , .,i,,,, , , , , , , , , , , ,
1 10 100 1000 10000 (Millions) Figure 1. Numbers of eggs estimated to have been entrained by PNPS in 1990 had it operated at full pump flow by species or species group (dominants only) including all egg species combined. The period of occurrence observed in 1990 is also indicated. l M M M M M M M M M M M M 5M M M M 'M M
~
' ~
+ .
y m m m w-- 3- u -. > w SPECIES AND OCCURRENCE PERIOD Clupea harengus h_. (April-May, November-January) -
-5,943,874 l Enchelyopus cimbrius (April-November) - 40,669,440 l j
Tautoga onitis (June-September) -' 8,720,243
-134,802,317 l Tautogolabrus adspersus (June-September)
Ulvaria subbifurcata (April-July) - 16.056,794. l 1 , Pholis gunnellus (January-May) - 12.268.408 l
* .60,886,295 l Ammodytes sp. (January-June) 4.611.566 j Scomber scombrus (May-August)
- 26,003,576 l Myoxocephalus spp. (February-June) 7,829.710 l Liparis spp. (March-June)
I Pseudopleuronectes americanus (April-June) - 7.337.297 l. I I Total Larvae
- 353,367.161 -[ i
- i e i n 10 100 1000 1
(Milfions) 1990 had it operated at full pump Figure 2. Numbers of larvae estimated to have been entrained by PNPS in The period of occurrence observed flow for each dominant species including all larvae combined. in 1990 is also indicated. f
I 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, Linaris spp.; radiated shanny, Ulvaria subbifurcata; sculpin, Mvoxocephalus spp.; rock gunnel) suggested that the percentage of original larval production contributing to entrainment by PNPS Unit 1 was less than 1.0 (Marine Research 1978). For twelve additional categories of eggs and larvae (see Marine Research 1978) considered to be more widely distributed in Cape Cod Bay, percentages contributing to entrain-ment were smaller, the highest being 0.12% (labrid-Limanda eggs). If entrainment of ichthyoplankton at PNPS represented a significant source of mortality in western Cape Cod Bay, the losses might be reflected in finfish collections in the PNPS area. A review of indices of relative abundance for some species based on otter trawl and gill net sampling by Massachusetts Division of Marine fisheries personnel (Lawton et al.1990; V.J. Malkoski, B.C. Kelly, personal communication) does not indicate any long-term steady declines among Atlantic herring, pollock, or tautog. I Several species, on the other hand, have displayed recent declines in abundance. These include cunner, windowpane (Scochthalmus acuosus), yellowtail flounder (Limanda ferrucinea), and Winter flounder. In these cases, however, commercial landings, stock _ assessment research, and other monitoring studies indicate that these delines appear to be widespread, extending all along the Mascuhusetts coastline (MDMF 1985, Foster 1987, Howe et al.1988, NOAA 1989, Marine Research 1990). Therefore, these specific I a_
declines appear to be the result of natural population variation H- probably coupled with overfishing. D. Es.tentiaL_Pumo Effects PNPS was involved in a long-term outage which began in April 1986 and continued into 1989. During most of this period only one of two main circulating water system (CWS) pumps was operating I (flow = 155,000 gpm, 9.78 m8 per second, compared with 310,000 gpm or 19.56 m8 per second, when the plant operates with two pumps). Beginning in late March 1987, intermittent use of a single circulating seawater pump made it basically unavailable for entrainment sampling, leaving only one or occasionally two Salt Service Water System (SSWS) pumps in service, each with a capacity of about 2500 gpm, or 0.16 m8 per second. From May through early September 1987 sampling continued with only the SSWS pump (s) providing flow for entrainment sampling. This situation also occurred from April through late August 1984 although two SSWS pumps functioned throughout that period. To compare the response of ichthyoplinkton to different pump regimes, densities per 100 m8 of water were compared for single SSWS pump periods (1987), two SSWS pump periods (1984), single CWS pump periods (1986, 1988), and two CWS pump periods (1983, 1985, 1990). Statistical comparisons involving these data were restrict-ed primarily to the May through August time frame when sampling was possible and the stated pump schedules were consistently main-tained; the 1987 da . set forced the exclusion of April from the 11
statistical tests because no sampling occurred in April 1987 due to uncertainty concerning the pump use schedule at that time. April data from the remaining years were included in graphicd analyses however (see below). Collectionsmadeduringthesebonthsin1989 did not falt clearly into any specific pump use category because the plant was returning to service, and CWS purp operation varied between one and two pumps. Only June and August 1989 were consistently sampled under one regime (all pumps in service). During the May through August period of 1990 all pumps remained in service. When collections were first made in 1984 using the relatively low-volume SSWS pumps, an assumption was made that ichthyoplankton would continue to be sampled in proportion to its abundance in the Rocky Point area since larval fishes, especially the small ones, show little directional swimming ability and pelagic eggs certainly drift passively. Results reported in the 1986 annual PNPS report (Marine Research 1987) indicated that April-August 1984 larval entrainment collections (2 SSWS pumps only) were so low that local I populations did not. appear to be impacteC in similar proportion by the SSWS pumps as by the CWS pumps. When 1987 larval data became available, the limited influence of the SSWS pumps became more apparent. May-August larval densities for 1987 when only one SSWS pump was used were exceptionally low each month, even when compared
.with 1984i Egg densities in 1987 ranked lowest over the 1983-1987 period only for August.
I I a
Mean densities per 100 m3 of water for total eggs and total larvae, May-August 1983-1990 were examined using a nonparametric, single classification, Kruskal-Wallis test; data obtained on May 30, June 25, and August 19, 1987 were omitted because those samples were taken during brief periods of single CWS pump operation. For the Kruskal-Wallis test individual sampling dates were used. No significant difference wt 'oparent among years for eggs (p = 0.05) but a very highly signifiwant difference (p < 0.001) was found for larvae. Nonparametric multiple comparisons among years for larvae showed no significant difference between 1989 and 1990 or between 1983,1985, and 1988 while 1984, 1986, and 1987 dif fered from those two groups and from each other. The summed ranks as well as results of the multiple comparisons (indicated by vertical bars) were as follows: I May-) m st 198bl990 M SUM M SCM ECGS PUXPS LW')E PCMPS 1989 - 1030 ( E or 1 GS 0.0.S.) 1990 1159 (E) 1988 - 903 (1 G S 0.0.S.) 1989 1105 ( E or 1 CWS 0.0.S.) 1985 - 846 (E) 1983 947 (E) 1983 - 791 (E) 19 5 930 (E) 1990 - 769 (E) 1988 814 (1CWS0.0.5.) I 1986 - 734 (1CWS0.0.5.) 1986 8 665 (1CWS0.0.S.) 1984 - 640 (2SSWS) 1984 l 518 (2SSWS) 1987 - 617 (1SSWS) 1987 l189 (1SSWS) 8.77.9.s. Kruskal-WallisCoeffleient 49.47** 0.0.S.=OutOfService 13 1
I Figure 3 presents the monthly means averaged within pump operation categories for the April-August time frame. Data for 1990 were averaged with the corresponding data from 1983 and 1985, the yeare of full operation; however April 1990 was excluded because only one CWS pump was in service at that time. Larval densities separated distinctly, particularly when sampling occurred only with one or two salt service water pumps. Data for 1989 with rixed pump usage varied between the all and one CWS pump regimes but in a consistent manner. June and August with all pumps in service during each sampling period ranked above the other years. May and July with two of five and one of four dates with all pumps in service, respectively, showed monthly means which fell between the all and one CWS pump values. April, also having one of four I dates with all pumps operating, fell below the one CWS pump category but well above the two SSWS pumps mean for that month. The fact that the overall May-August data set for 1990 larvae ranked significantly higher than 1983 and 1985, the other full-operation years, suggests that larvae were relatively abundant during the late-spring and summer of 1990. Similarly, that 1989 ranked just below 1990 and was not found to be significantly different from 1990, in spite of the six dates when one CWS pump was out of service, suggests that in general larvae were relatively abundant during that period. The apparent reduced susceptibility of larvae to the SSWS A. pumps was further indicated by sampling on May 30, 1987 when collections were made while one CWS pump was placed into service 14 l
== mm. mm um um = = = = = = -
e == mm .
- m. == ==
Fish Eggs. Fish Larvae Mean Density /100 Cubic Meters Mean Density /100 Cubic Meters 10000 1000: j*
~
too * ~ ' - ~ (~ ~ . . ___ l
/ .
l \ 10 :
/
100 :
' I
~
G !
-. 1 :
h 0.1 -
~ ~
g . . . 0.01 '
- Apr May Jun Jul Aug Apr May Jun Jul Aug
- 1 SSWS(1987) - 2 SSWS(1984) 1 CWS O.O_S(1986.88)
--- alt. (1983.85.90) 2 CWS O.O.S(1989)
PHPS Data. Figure 3. Mean monthly densities per 100 m' of water for total eggs and total larvae entrained at PNPS within four pump operation categories during the April-August period of 1983-1990. Values.for 1983, 1985, 1990 are averaged (all pumps operating) as are 1986, 1988 (1 CWS pump out of service). See text for details.
I for a short period. On May 28 no larvae were obtained while sampling under the influence of one SSWS pump. Two days later on May 30 a mean density of 132 larvae per 100 m3 was obtained consisting of eight species. On June 4, again with only one SSWS pump operating, two larval species with a combined mean density of 2 per 100 m8 of water were taken. A comparison of the number of ichthyoplankton species recorded from May through August over the 1983-1990 period indicated that 1987 was clearly the lowest with 13 overall (23 with inclusion of the three dates when one CWS pump was in use); 1984 and 1986 followed with 29 each. Numbe.rs of r secies ranged from 30 (1990) to 35 (1989) during years when at least one CWS pump Wes in use. The low species count in 1987 was due primarily to a scarcity of I larvae. Only four species of larvae were recorded over the May-August period of 1987 compared with 24 (1984) to 32 (1989) over the other years. Numbers of egg species were somewhat more consistent with 9 being taken in 1987 compared with 15 (1984 and 1988) to 20 (1989) during the other years. Including May 30, June 25, and August 19, 1987 when a single CWS pump was in service brought the 1987 totals up to 15 species of eggs and 16 species of larvae. The low densities of larvae in 1984 and the strikingly low densities in 1987 over the spring and summer period strongly suggest that ichthyoplankton populations near PNPS were not impacted in similar proportion by the SSWS pumps as by the main circulating seawater pumps. A sharp decline in larval densities occurred between 1984 and 1987 values, suggesting that dropping I, a_
I from two to one SSWS pump eliminated entrainment of many larvae. The intermediate values for 1986 and 1988, when one CWS pump was in service, ranking between 1984/1987 and 1983/1985/1990 suggests a direct relationship between pump flow and larval entrainment. Values for 1989 with variable pump operation further support this conclusion (Figure 3). Apparently the relativcly low flow of the SSWS pumps has very limited influence on drawing larvae into the
.I intake embayment area and subsequently through the PNPS condensers.
These results could reflect mainly physical flow effects acting upon free-floating larvae or perhaps an active larval swimming ability, permitting an increasing number of them to avoid entrain- ! ment as pump capacity declines. For example, 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)% hen two seawater pumps operate t than when only one seawater pump operates, or even when one 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 Nater mass. Also the more widespread the influence of a particular pumping rate, the higher the probability that high-density ichthyoplankton patches will be entrained. The role which vertical distribution plays may be of great importance as well, as the smaller pumps probably draw water over a more restricted vertical profile, one which may not coincide with the presence of many eggs and larvae.
E 17
l I Although no significant difference was detected among years for total eggs, years did rank in similar manner to the larvae. Notable exceptions occurred with 1988 (one CWS pump) which ranked second among the eggs and 1990 (2 CWS pumps) which ranked third among the fully operational years and fifth overall. The one SSWD pump year (1987) again ranked last. As mentioned for larvae, the high ranking of 1989 among the eggs taken from May thrc.lgh Augurt, when one CWS pump was out of service on six occasions, suggests that eggs were generally abundant during those months. It is important to keep in mind that all comparisons based on different pump capacities were made without knowledge of ichthyo-plankton populations around Rocky Point. The observed rankings could have beer. due entirely, or in part, to differences in production among the eight years, although that would appear to be an extraordinary coincidence given the well-defined relationship between ichthyoplankton densities and PNPS flow. Perhaps, on the contrary, the f act that densities ranked according to pump capacity in spite of high inter-year variability suggests how strong this relationship may be. E. Lobster Larvae The scarcity of larval lobsters (Homarus americanus) 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 four million dollars (Lawton et al. 1983). Among lobstermen working inshore waters, this increased to 1381 tons valued at $6.8 million in 1985 (Hoopes 1986) 18 I l 1 I_
I and 1485 tons valued at $7.5 million in 1986 (Hoopes 1987). Fron 1987 through 1989 annual landings ranged from 1262 tons to 1385 i tons with generally rising value (peak = $8.1 million in 1988; Hoopes 1988, 1989, 1990). Neuston sampling conducted in the northwest sector of Cape Cod Bay (Lawton et al. 1983; Matthiessen and Scherer 1983 J 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 regions. Sampling around Rocky Point from 1974 through 1977 showed consider-ably more late-stage larvae than young larvae (Lawton et al.1983) . That, coupled with the prevailing counterclockwise Cape Cod Bay currents, suggests that larvae may arrive from the north. Sampling , at the mouth of the Cape Cod Canal also suggests that large numbers of larvae entet Cape Cod Bay from Buzzards Bay and perhaps the Canal itself (Matthiessen and Scherer 1983; Matthiessen 1984). Regardless of source, larval lobsters appear to be}}