ML20029C813: Difference between revisions
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a high-rise otter trawl to monitor pelagic fish abundance, while the monitor-ing in the study area is conducted with 5.4.2.3 Demersal Eish gill nets. | a high-rise otter trawl to monitor pelagic fish abundance, while the monitor-ing in the study area is conducted with 5.4.2.3 Demersal Eish gill nets. | ||
General Mlantic MackcIn1 Many species (hake species, rainbow smelt, yellowtail flounder, and winter Atlantic mackerel abundance has remained flounder), showed a significantly lower steady in the study area and increased in CPUE during the operational period (Table the Gulf of Maine (Table 5-18). The index 5-22) that was a continuation of a trend of Age 1+ Atlantic mackerel biomass for that began in the early 1980s. This trend the Gulf of Maine has increased dramati- is not attributable to the operation of cally since 1983 (NOAA 1992). There were Seabrook Station because it began prior no significant differences in CPUE between to the operation of the station. The l | General Mlantic MackcIn1 Many species (hake species, rainbow smelt, yellowtail flounder, and winter Atlantic mackerel abundance has remained flounder), showed a significantly lower steady in the study area and increased in CPUE during the operational period (Table the Gulf of Maine (Table 5-18). The index 5-22) that was a continuation of a trend of Age 1+ Atlantic mackerel biomass for that began in the early 1980s. This trend the Gulf of Maine has increased dramati- is not attributable to the operation of cally since 1983 (NOAA 1992). There were Seabrook Station because it began prior no significant differences in CPUE between to the operation of the station. The l | ||
decrease in the CPUE of demersal fish the preoperational and operational peri-ods, although CPUE in the operational year species in the study area is similar to of 1992 was the second highest recorded the decline in the indices of abundance to date, observed in the Gulf of Maine and Georges 4 Bank, with the exception'of hake species (NOAA 1992). The general decrease in Solny Do2 fish abundance of demersal fish in both the j study area and the Gulf of Maine-Georges j Until the early 1980s, spiny dogfish Bank area is probably due to a factor that CPUE in the study area was negligible. operates on a larger geographic scale than Since then, CPUE of spiry dogfish in- Seabrook Station, such as commercial creased to its present status as one of overfishing of demersal fish stocks, the five most abundant fish. The NMFS biomass estimate for spiny dogfish in the Gulf of Maine - middle Atlantic region has | decrease in the CPUE of demersal fish the preoperational and operational peri-ods, although CPUE in the operational year species in the study area is similar to of 1992 was the second highest recorded the decline in the indices of abundance to date, observed in the Gulf of Maine and Georges 4 Bank, with the exception'of hake species (NOAA 1992). The general decrease in Solny Do2 fish abundance of demersal fish in both the j study area and the Gulf of Maine-Georges j Until the early 1980s, spiny dogfish Bank area is probably due to a factor that CPUE in the study area was negligible. operates on a larger geographic scale than Since then, CPUE of spiry dogfish in- Seabrook Station, such as commercial creased to its present status as one of overfishing of demersal fish stocks, the five most abundant fish. The NMFS biomass estimate for spiny dogfish in the Gulf of Maine - middle Atlantic region has ((aken increased steadily since 1985 to record or near-record levels in 1990 and 1991 The average CPUE of hake species was (NOAA 1992). Spiny dogfish increased in significantly greater during tha preopera- j relative abundance from 2% in 1963 to 41% tional period than the operational period in 1986 (NOAA 1992). The dramatic in- (Table 5-22). Ilowever, the index of bio-5-60 1 | ||
FISil TABLE 5-22. | FISil TABLE 5-22. | ||
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SEABROOK STATION U . \ | SEABROOK STATION U . \ | ||
j, | j,((,ho.. . Olecnarge | ||
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g ypTON Suenock # | g ypTON Suenock # | ||
Latest revision as of 06:00, 15 March 2020
| ML20029C813 | |
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| Site: | Seabrook  |
| Issue date: | 08/31/1993 |
| From: | NORMANDEAU ASSOCIATES, INC. |
| To: | |
| Shared Package | |
| ML20029C810 | List: |
| References | |
| XXIV-1, NUDOCS 9404290224 | |
| Download: ML20029C813 (350) | |
Text
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North Atlantic April 22,1994 ENCI.OSUltE I TO NYN-94050 NORMANDEAU ASSOCIATES TECIINICAl,ItEPORT XXIV-1 l
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! 9404290224 940422 PDR ADOCK 05000443
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l L l l I i f' SEABROOK ENVIRONMENTAL STUDIES, 1992 A CIIARACTERIZATION OF ENVIRONMENTAL CONDITIONS IN THE HAMPTON-SEABROOK AREA DURING THE OPERATION OF SEABROOK STATION TECHNICAL REPORT XXIV-1 Prepared for < NORTH ATLANTIC ENERGY SERVICE CORPORATION P.O. Box 300 Seabrook Station Seabrook, New Hampshire 4 1 Prepared by NORMANDEAU ASSOCIATES INC. 1' 25 Nashua Road Bedford, New Hampshire 03110-5500 i R-13666 August 1993 j
. _ . . . . - _ m _
6- up mm A --A e as 4 re- -4 n - p TABLE'0F CONTENTS ' SECTION 1.0 - EXECUTIVE
SUMMARY
SECTION 2.0 - WATER QUALITY
- SECTION 3.0 - PilYT0 PLANKTON SECTION 4.0 - ZOOPLANKTON SECTION 5.0 - FISil SECTION 6.0 - MARINE HACROBENT110S SECTION 7.0 - SURFACE PANELS SECTION 8.0 - EPIDENTIIIC CRUSTACEA SECTION 9.0 - ESTUARINE BENTil0S SECTION 10.0 - SOFT SIIELL CLAH (NYA ARENARIA)
T
'% ,--4, . -
f f , 4 TABLE OF CONTENTS PAGE 1.0 EXECUTIVE
SUMMARY
. . . . . . . . . . . . . . . . . . . . . . , , . . 1-1 1.1 APPROACH . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1.2 STUDY PERIODS . . . . . . . . . . . . . . . . . . . . , , 1-4 1.3
SUMMARY
OF FINDINGS . . . . . . . . . . . . . . . . '1-5 1.4 LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . 1-12 i I I
.1 I
.l 1-1
- . - - .. . - .- ~_.
4
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LIST OF FIGURES i PAGE 1-1. Sequence of events for determining if there are environmental changes due to the operation of Seabrook Station . .. ..... 1-2 1-2. Average daily power level at Seabrook Station in 1991 and 1992 .. 1-6 1 s u I j LIST OF TABLES
~
1-1.
SUMMARY
OF BIOLOGICAL COMMUNITIES AND TAXA MONITORED FOR EACH POTENTIAL IMPACT TYPE . . . . . .. .. ............. 1-3 1-2; MONTHLY CHARACTERISTICS OF SEABROOK STATION OPERATION IN 1990, 1991 AND 1992 . . . . . . . .. . .. . . . .. ........ 1-6 N 1 1-11
EXECUTIVE
SUMMARY
1.0 EXECUTIVE
SUMMARY
the thermal discharge. The intake is also expected to have only a localized ef fect, . 1.1 APPROACH and this effect is characterized by the entrainment and impingement sampling The purpose of this report is to assess programs, whether there have been changes in the " balanced, indigenous populations" in the A basic assumption in the monitoring nearfield coastal waters of New ilampshire program was that there are two major as a result of commercial operation of sources of naturally-occurring variabil-Seabrook Station, which began in August ity: (1) that which occurs among dif-1990. The ability to determine whether ferent areas or stations, i.e., spatial, operation of the plant has affected the and (2) that which varies in time, from aquatic biota in the area is dependent daily to weekly, monthly or annually. In upon a systematic approach to impact the experimental design and analysis, the assessment, incorporating both temporal Seabrook Environmental Program has focused and spatial components (Figure 1-1). on the major source of variability in each Potential operational effects could be community type and then determined the ruled out if: (1) results from the magnitude of variability in each com-operational period were similar to pre- munity. The frequency and spatial vious (preoperational) years, given the distribution of the sampling effort were natural variability in the system; or, (2) determined based on the greatest sources dif ferences within the operational period of variability for each parameter (NAI were observed in both nearfield and far- 1991). Biological variability was field areas. In addition, other potential measured on two levels: species and sources of change have been investigated community (Table 1-1) . A species' abun-before the conclusions specified within dance, recruitment, size and/or growth are this report were drawn. This study design important for understanding operational was modeled af ter objectives discussed by impact, if any, should changes occur in Green (1979), which have been described these parameters between stations or over in more detail previously (NAI 1991). time. These parameters were monitored for selected species from each comunity type. The validity of the impact assessment Selected species were chosen for more model is based on comparisons between intensive study based on either their nearfield stations within the influence commercial or numerical importance, of Seabrook Station and farfield stations sensitivity to temperature, potential as outside its influence. Thermal plume a nuisance organism, or habitat prefer-modeling as well as operational validation ence. Overall community structure of the clearly indicates this to be true for biota, e.g., the number and type of thermal effects. The extent of a +3*F species, total abundance and/or the (1.7"C) isotherm covered a relatively dominance si.ructure, was also reviewed to small 32-acre surface area. Temperature determine phtnt impact, if any, in a way differences did not cxtend below the not detected by monitoring individual thermocline due to the buoyant nature of species. Trends in these parameters were i 1-1
SEQUENCE OF EVENTS FOR DETERMINING IF THERE ARF. ENVIRONMENTAL CHANGES DUE TO OPERATION OF SEABROOK STATION is Operational
, Period YES stmtlar to m
. No previous years impact at nearfield station 7
NO U Operational Period YES No nearfield D-similar to Impact farfield
?
NO Observed changes related to NO m No r plant impact operation
?
i YES Y Operational Impact Figure 1-1. Sequence of events for determining if there are environmental changes due to the operation of Seabrook Station. Seabrook Operational Report,1992. 1-2
EXECUTIVE
SUMMARY
TABLE 1-1.
SUMMARY
OF BIOLOGICAL COMMUNITIES AND TAXA MONITORED FOR EACH POTENTIAL IMPACT TYPE. SEABROOK OPERATIONAL REPORT, 1992. LEVEL MONITORED SELECTED HONITORING SPECIES / AREA IMPACT TYPE SAMPLE TYPE COMMUNITY PARAMETERS Intake Entrainment Microzooplankton x x Macrozooplankton x x Fish eggs x Fish larvae x x Soft-shell clam larvae x Cancer crab larvae x Impingement Juvenile / Adult fish x x i Discharge Thermal Plume Nearshore water quality x Phytoplankton x x Lobster larvae x ,- Intertidal / shallow subtidal macroalgae ! and macrofauna x x l Subsurface fouling j community x x I Detrital Mid-depth / deep
- Rain macrofauna and macroalgae x x Bottom fouling community x Demersal fish x x Lobster adults x Cancer crab adults x Estuary Cumulative Estuarine temperature x Sources Soft-shell clam spat and adults x Estuarine fish x x 1-3
.~
l EXECUTIVE
SUMMARY
reviewed against the natural variation in evaluated through continued monitoring at community structure, sampling .ations established during the preoperational period, with statistical A ;evious Summary Report (NAI 1977) comparison of the results at both the co . luded that the balanced indigenous community and the species levels. The community in the Seabrook study area null hypothesis in all tests is that there should not be adversely influenced by loss has been no change in community structure of individuals due to entrapment in the or selected species abundance or biomass circulating water system (CWS), exposure that is restricted to the nearfield area. reviewed against the natural variation in This in turn would indicate, based on the community structure. approach outlined in Figure 1-1, that the balanced indigenous populations have been A previous Summary Report (NAI 1977) maintained. concluded that the balanced indigenous community in the Seabrook study area should not be adversely influenced by loss 1.2 STUDY PERIODS of individuals due to entrapment in the circulating water system (CWS), exposure Environmental studies for Seabrook to the thermal plume or exposure to Station began in 1969 and focused on plant increased particulate material (dead design and siting questions. Once these organisms) settling from the discharge. questions were resolved, a monitoring The current study continues to focus on program was designed to assess the the likely sources of potential influence temporal (seasonal and yearly) and spatial from plant operation, and the sensitivity (nearfield and farfield) variability of a community or parameter to that influ- during the preoperational period as a ence within the framework of natural baseline against which to evaluate variability (Table 1-1). Naturally, a conditions during plant operation. This community or species within the study area report focuses on the preoperational data might be affected by more than one aspect collected from 1976 through 1989 for of the CWS. Results from this monitoring fisheries studies and from 1978 through program will be discussed in light of that 1989 for most plankton and benthic aspect of the cooling water system that studies; during these years sampling has the greatest potential for affecting design has consistently focused on pro-that particular component of the biolog- viding the background to address the ical community. question of operational effects. Entrainment and impingement were ad- Commercial operation of Seabrook dressed through in-plant monitoring of the Station began intermittently in July and organisms entrapped in the circulating August 1990, and continued for periods of water system (CWS). The effects on the approximately three weeks in September and balanced, Indigenous population of aquatic October. Therefore, August 1990 is 'l biota in the waters in the vicinity of the considered the beginning of the opera- 1 CWS intake and discharge structures were tional period for the purposes of this 1-4
l I EXECUTIVE SUHFJutY environmental assessment. Af ter operation overwhelming influence of high tempera- ) at 100% for less than a week at the begin- tures in 1991. ning and end of November, the plant operated nearly continuously from December Annual mean surf ace and bottom salinity 1990 through July 1991 when it was shut levels in 1992 declined from 1990 and 1991 ) down for routine maintenance. Resumption levels, dropping to the lowest level of full power operation began again in observed to date. This decrease, which October 1991 and continued through a began in June 1990, prior to station second maintenance outage in late Septem- operation, occurred at all three stations, ber 1992. Full power operation began indicating it was part of a regional again in November 1992 (Figure 1-2) . The phenomenon. Precipitation was higher than circulating water system was active average during some of the months in 1991 throughout 1990,1991, and 1992, although and 1992, but does not appear to account occasionally at reduced levels (Table for the observed differences. 1-2). , Surf ace and bottom dissolved oxygen in l 1992 increased from the lower than average 1.3
SUMMARY
OF FINDINGS values observed in 1991 to values that , were near the preoperational average. l Water Ouality These variations at least in part can be related to changes in water temperature. Physical and chemical water quality For the operational period (1991 and 1992 I parameters were reviewed as part of the combined), mean surface and bottom average biological assessment. Annual average dissolved oxygen values were significantly surface and bottom temperatures in 1992 lower than the average during the pro-were lower thsn average, ending the trend operational period at all three stations. l of increasing temperatures that began in The seasonal cycles in 1991 and 1992 were 1987/1988. The seasonal cycles, however, typical of the patterns observed in were the same as in previous years. previous years. Spatial differences in average surface and bottom temperatures that were apparent Nutrient concentrations in 1991 and 1992 during the preoperational period continued were generally lower than in recent years, in 1992. The average temperature was but showed seasonal patterns that were highest at intake station, followed by similar to previous years. Concentrations discharge station, with lowest temperature of nitrate, ammonia, and total phosphorus observed at the farfield station. When in 1992 were lower than the average of the operational period (1991 and 1992) is recent preoperational years. The average considered as a whole, average surface and of these nutrients and orthophosphate was bottom temperatures at all three stations significantly lower during the operational were significantly higher than the average period at all three stations, for the recent preoperational period (1987-1989, when all three stations were sampled concurrently), due mainly to the 1-5
EXECUTIVE
SUMMARY
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, g g y. 35 JAN FE8 MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FES MAR APR MAY JUH JUL AUG REP OCT NOV OEC 196I 1992 Figure 1-2. Average daily power level at Seabrook Station in 1991 and 1992.
Seabrook Operational Report,1992. TABLE 1-2. HONTHLY CHARACTERISTICS OF SEABROOK STATION OPERATION IN 1990, 1991 AND 1992. SEABROOK OPERATIONAL REPORT, 1992. DAYS OF CIRCULATING WATER SYSTEM AVERAGE DAILY OPERATION FLOW (mgd) MONTH 1990 1991 1992 1990 1991 1992 Jan 31 31 31 324 584 585 Feb 28 28 29 564 580 578 Mar 31 31 31 563 580 581 Apr 30 30 30 563 531 576 May 31 31 31 562 581 581 Jun 30 30 30 563 578 593 Jul 31 31 31 582 535 593 Aug 31 21 31 588 253 583 Sep 30 26 29 588 257 314 Oct 31 31 24 590 552 159 Nov 30 30 30 590 590 566-Dec 31 31 31 589 591 563 1-6 i
EXECUTIVE
SUMMARY
Although water quality parameters showed abundance that were observed during the some changes in 1991 and 1992, these preoperational period were maintained differences were not restricted to the during the operational period. The nearfield area. Spatial differences typical seasonal pattern of spring and observed during the preoperational period fall blooms continued. Chlorophyll a continued in 1991 and 1992. There was no concentrations roughly parallelled the evidence of a change associated with the seasonal trends of total phytoplankton operation of Seabrook Station. abundance. There were no changes in the phytoplankton community that were re-stricted to the nearfield area. This Ehylaniftnkton suggests that Seabrook Station has had no discernible effect on phytoplankton. Primary producer assemblages have shown a shift in community composition and an Paralytic shellfish poison toxicity increase in total abundance throughout the levels are monitored to determine if study area during the operational period. Seabrook Station is in any way enhancing The focus of the ultraplankton (defined the occurrence of red tide. Only two as species measuring <10 pm) assessment shellfish bed closures related to red tide was a nearfield-farfleid operational occurred in 1991 and none occurred in comparison. Since the last preoperational 1992. As in the past, red tido events in phytoplankton collection in 1984, the New Hampshire coincided with those in laboratory techniques available for use adjacent states. There were no outbreaks have improved, and research on the of red tide that were restricted to New ultraplankton has proliferated. As a Hampshire. result, ultraplankton appear more numerous during the operational period, The ultraplankton community was dominated by Zooolankton colonial Cyanophycean at both nearfield and farfield stations. Other studies in Entrainment of plankton by the circulat-the Gulf of Mnine have confirmed this ing water system represents both a loss trend. The phytoplankton community to the various plankton communities, and I (species measuring >10 pm) has also ultimately to adult populations, due to undergone changes throughout the area. entrainment of egg and larval forms. In Many diatom species have decreased in 1992, estimates of bivalve larvao entrain-importance, replaced by higher numbers of ment were made from April, May, and June species such as the yellow green alga in plant collections. Siste11a sp. was l l Phaeocystis ponchetel. During the the most abundant species entrained, and preoperational period, the phytoplankton #ytilus edulis and Solenidae were second-community was highly variable among years, arily important. The level of bivalve so it is not surprising that this trend larvao entrainment was an order of continued. There were few differences magnitude lower than the previous two among stations in community composition, years, probably because entrainment however. Spatial differences in total samples were collected only through the 1-7
l EXECUTIVE
SUMMARY
third week of June, before larvae of fshore stations, they were ascribed to area-wide ; reached peak densities. In' addition,1992 long-term trends rather than a result of offshore densities of dominant /fytllus Seabrook Station's commercial operation. edulls and most other taxa were substan-tially lower than in 1991 and during the The microzooplankton community was preoperational period, strongly influenced by seasonal patterns of the numerically important copepods Ichthyoplankton entrainment was estimat- 01thona sp., Pseudocalanus sp., and
- ed in 1992 f rom samples collected f rom Pseudocolanus/Calanus nauplii. Collec-January through August and December, tions from 1990,1991 and 1992 generally Atlantic mackerel and cunner /yellowtail showed seasonal patterns that were typical flounder were the most common egg taxa of previous years. The species composi-that were entrained, as was true in 1991. tion among the three stations during the
- The larval species most likely to be operational period showed no significant entrained in 1992 were rock gunnel, differences. Abundances of some of the Atlantic seasnail, grubby, and American dominants, such as copepod Eurytemora sp.
sand lance. Entrainment estimates in 1992 copepodites , Pseudocolanus/Calanus nauplii were roughly comparable to 1990 and 1991 and Olthona sp. copepodites and adults, estimates. The abundances of most of the were significantly different during the commonly entrained species in offshore operational period when compared to the samples were similar to average abundances preoperational period. However, these during the preoperational period, suggest- changes were not. restricted to the ing that entrainment had a negligible nearfield station, suggesting a regional effect on offshore populations. phenomenon. The ichthyoplankton egg and larvae The macrozooplankton comunity has shown communities showed the distinct seasonal seasonal changes that were strongly progression of dominants that typified influenced by the population dynamics of i previous years. However, some of the dominant copepods Centropages typicus and dominant species showed area-wide changes Calanus finmarchicus and larval forms of in abundance during the operational benthic species such as barnacles and period. Yellowtail and winter flounder Concor spp. Seasonal changes were and Atlantic herring larvae all had observed at all three stations in synchro-decreased abundances during the operation- ny both during the preoperational and al period, parallel 11ng long-term trends operational periods. 'Ihe macrozooplankton
~
j in the adults and in the Gulf of Maine as holo /meroplankton community in 1992 showed { a whole. Operational abundances of cunner some differences in the late-fall and and pollock larvae were also lower than winter community, and abundances of
- during the preoperational period, while dominants varied from preoperational Atlantic mackerel and Atlantic cod levels in winter. However, these varian-densities were higher during the opera- ces were noted at all three stations and i tional period. As these differences were thus deemed to be part of natural l occurred at both near- and farfield among-year variability. Average densities a
1-8 i l
EXECUTIVE
SUMMARY
l 1 of selected macrozooplankton species average, due mainly to record-low catches during the operatfonal period were similar of Atlantic herring in 1991. However, to the preoperational period, with one total catch increased in 1992 as a result enception: Cancer spp. were more numerous of increased numbers of Atlantic herring, during the operational period at all three Atlantic mackerel, and spiny dogfish. stations. NOAA reports that stock biomass of herring and mackerel has been increasing in the l Gulf of Maine since the early 1980s due Imoinnement to decreased fishing pressure. In addition, NOAA sttrveys have shown a l A total of 1174 fish were impinged at dramatic increase in spiny dogfish in the Seabrook Station, an increase from the Gulf of Maine since 1980. There has been 1019 recorded in 1991 and 499 in 1990. no significant difference between near-Impingement rates were highest following field and farfield stations, indicating strong northeastern storms, which occurred that Seabrook Station is having no in October 1991 and December 1992. The discernible effect on the pelagic fish species that were impinged were primarily community. demersal, such as flounders, lumpfish, and sculpin, although pelagic fish such as The total catch of demersal fish in the pollock, rainbow smelt and Atlantic study area has been steadily declining silverside were also susceptible. since 1989, a result of decreasing catches Impingement at Seabrook Station is less of dominants such as Atlantic cod, than any other electrical generating yellowtail flounder, and winter flounder. station in New England that has a marine In the Gulf of Maine, stocks of these intake and several orders of magnitude species have been decreasing since the less than recreational fishing losses. 1980s and are currently near record lows. A potential impact would be indicated by a significant change in abundance during Adult Fish Pooulation the operational period that was restricted to the nearfield station. This assessment potential impacts of Seabrook Station is complicated by the fact that the must be considered within the framework presence of lobster gear at the nearfield of long-term trends in the Gulf of Maine. station often prevented sample collection Catches of adult fish have shown changes in late summer, when catch of some species in the Hampton-Seabrook area that are, for were largest. Catches of two of the the most part, consistent with trends dominant demersal species were lower 4 observed in the Gulf of Maine. Pelagic during the operational period, but trends fish catches in the study area have been were not consistent among the three low since the early 1980s, following peak stations. Winter flounder catches were catches in 1978 and 1980. The average significantly lower during the operational total catch for the operational period period at the nearfield and the southern (1991 and 1992) at all three stations farfield station, but there was no remained lower than the preoperational significant difference at the northern 1-9
l l EXECUTIVE
SUMMARY
)
Benthos f arfield station. Since this dif ference i was not restric'ted to the nearfield , station, it does not appear to be related Composition in the benthic macroalgal to operation of Scabrook Station. and macrofaunal communities has been Atlantic cod catches decreased at all relatively stable during the monitoring three stations during the operational program, although year-to-year variation i period. However, at the nearfield in the abundance or biomass of the i station, where catches have historically dominants has been evident throughout the , been lowest, the decrease was especially program. August benthic collections at pronounced. It is uncertain whether this each station during the operational period , change 1:; indicative of an effect of had similar species composition to the Seabrook Station or is simply part of majority of collections from previous natural variability. years. Most community parameters such as species richness and total abundance or biomass showed no changes that were Surface Panels restricted to nearfield stations, There were some exceptions, however. Total Surface panels are utilized to monitor intertidal algal biomass -in August was g the recruitment and development of the significantly lower during the operational
. fouling community, many of which are also period at the nearfield station only, due
. dominants in the hard substrate benthic mainly to reduced biomass of dominant 4 community. The assemblage on surface Chondrus crispus biomass. When triannual panels shows a regular seasonal progres- samples were considered, however, there sion in recruitment and development. The were no significant differences-in total patterns observed during the operational biomass or biomass of Chondrus crispus. period were similar to those observed The number of macrof aunal taxa at the during the preoperational period. Species nearfield shallow subtidal station was richness, total abundance, and biomass at significantly higher than the preopera-the nearfield stations during the opera- tional mean, whereas there was no signifi-tional period showed no difference from cant difference at the farfield station. the preoperational average. The amphipod This difference was due to the 1990 Jassa falcata, bivalve Mytilidae (mid- collections, which had higher-than-average depth stations only), and hydroid Tubu- density and species richness and a 1arla sp. , occurred less frequently during slightly different species composition. the operational period in comparison to In 1991 and 1992, macrofaunal species previous years. As this occurred at both richness and community composition became near- and farfield stations, it was more similar to the preoperational indicative of a regional trend rather than average. At the mid-depth intake station, . an effect of Seabrook Station. total algal biomass and total macrof aunal density during the operational period was , significantly lower than during the I preoperational period. l 1-10
_ _ _ _ _ _ _ __ _. _ .~ _ . . _. l EXECUTIVE
SUMMARY
All of the selected benthic species are suspected to originata in the Gulf of showed evidence of recruitment and growth Maine and Georges Bank, and thus density during the operational period. Some of increases are probably unrelated to local the dominant species had abundance or influences, including Seabrook Station, biomass that was significantly dif ferent Total lobster catch declined in 1992. from previous years. However, most of the Preliminary catch estimates for 1992 from changes occurred at nearfield and farfield NOAA are also lower than 1991, and the stations, suggesting that these dif feren- difference is attributed to lower water ces were an arca-wide phenomenon. Two temperatures. Seasonal patterns in 1992 species showed changes that were restrict- were similar to previous years. However, ed to the nearfield area. The kelp there was no significant difference in Larninarla digitata has been declining in average catch between the operational and the shallow subtidal zone since 1989. The preoperational periods at the nearfield reduction has been more pronounced at the station, although a significant dif ference nearfield station, resulting in a signifi- was noted at the farfield station, cantly lower density during the operation- Catches of legal-sized lobsters were j al period. As this reduction began prior significantly lower during the operational to plant start-up, it is not related to period in comparison to the preoperational plant operation. The amphipod Ampichoc period, a result of the increase in the l rubricata, once a dominant in the inter- legal-size limit in 1990. tidal zone, was rarely collected from 1984-1989. Low numbers were collected at C6tches of Jonah crab in 1992 and during the farfield station beginning in 1990, the operational period were similar to but few have been collected at the previous years. Rock crabs, ' loss preva-nearfield station. As a result, densities lent in the study area than their conge-were significantly lower during the ner, were significantly higher in number operational period only at the nearfield in 1991 and 1992 in comparison to previous station. Tha patterns in Ampichoe density years at both nearfield and farfield appear to be part of a long-term trend stations. d rather than a result of the operation of Seabrook Station. Six lobsters were impinged in 1992, a decrease from the 29 impinged in 1991 and similar to the 4 that were impinged in Eolbenthic Crustaceji 1990. This level of impingement does not appear to be a threat to the lobster Lobster, and rock and Jonah crabs are population. Important predators in the Hampton-4 Seabrook region. Lobster larvae were
- significantly more abundant in 1991 and E
- Lty3rine Studies 4
1992 when compared to the preoperational period. No differences among stations Hampton-Seabrook estuary is monitored were detected. The Stage IV lobster primarily to determine if Seabrook larvae that are collected in New Hampshire Station's settling pond discharge into 1-11
-Es 2.. - 4-sa p EXECUTIVE
SUMMARY
Browns River has any effect on the nearby sof t-shell clam had a seasonal occurrence estuarine community. The estuarine and density level in 1992 and during the environment is typically exposed to operational period that was similar to extreme variations in temperature and previous- years. Young-of-the-year salinity. As a result, the biota are recruitment in 1992 was less than the tolerant to these conditions, and opportu- preoperational average at some flats, but nistic species often predominate. was similar to previous years at others. Temperature and salinity in 1992 were Survival of the young-of-the year to spat near-average. The number of taxa, total increased in 1992, but remained below-abundance, and abundances of dominant average. Juvenile stages also had lower species in 1992 were within the range of than average densities in 1992 Spat and previous years. The benthic community in juveniles are particularly susceptible to - Drowns River was similar to that at the predation by green crabs. High green crab farfield area in Mill Creek. There was catches in 1991 and 1992 coincided with no evidence of a detrimental effect of the low densities of its main prey species, settling pond discharge. Adult clams are af fected by human preda-tion from recreational clam digging'and The estuarine fish community was the disease sarcomatous neoplasia. Clam predominantly composed of Atlantic flats have been closed for four years, silverside, along with young-of-the-year eliminating the important f actor of human winter flounder, rainbow smelt, stickle- predation. However , low numbers of spat backs, and mummichog/ striped killifish and juveniles limited adult recruitment (rundulus spp. ) . Total CPUE was near its until 1992, when adult clam densities lowest point in 1992, although within the increased. The increase was most dramatic range of previous years. This was due at Flat 4, where neoplasia has historical-primarily to diminished catches of ly been absent. Changes in the soft-shell Atlantic silverside and winter flounder. clam population can be related to long-Atlantic silverside catches have been term cycles of recruitment, predation, and declining steadily since 1983, reaching possibly disease. There was no evidence their lowest point in 1992. Winter of an effect from Seabrook Station. flounder CPUE in the estuary has been decreasing since 1980, paralleling trends in the Gulf of Maine since 1983. In 1992, 1.4 LITERATURE CITED catches were the lowest to date. The low catches of estuarine fish in 1992 appear Green, R.H. 1979. Sampling design and to be a continuation of a long-term trend. statistical methods for environmental biologists. John Wiley and Sons, N.Y. Hampton-Seabrook estuary contains the 257 PP. ~ majority of New Hampshire's stock of the sof t-shell clam. Recruitment and survival Normandeau Associates Inc.1977. Summary of this important species is affected by document: assessment of anticipated a variety of factors including predation impacts of construction and operation and disease. Umboned larval stages of the of Seabrook Station on the estuarine, 1-12
3 EXECUTIVE
SUMMARY
coastal and offshore waters of Hampton-Saabrook, New H'ampshire.
. 1991. Seabrook Environmentel Studies, 1990. A characterization of environmental conditions in the Hampton-Seabrook area during the operation of Seabrook Station. Tech. Rep. XXII-II.
9 4 4 3 1-13 i l
.E \
TABLE OF CONTENTS PAGE 2.0 WATER QUALITY , . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2.1 INTRODUCTION
. . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.2 NETHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 h
2.2.1 Field Methods . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.2.2 Laboratory Methods . . . . . . . . . . . . . . . . . . . . . 2-2 2.2.3 Analytical Methods . . . . . . . . . . . . . . . . . . 2-2 2.3 RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 2.3.1 Physical Environment . . . . . . . . . . . . . . . . 2-3 2.3.2 Nutrients . . . . . . . . . . . . . . . . . . . . . . 2-17 2.4 DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . 2-19 2.4.1 Water Quality Characterization . . . . . . . . . . . . . . . 2-19 2.4.2 Effects of Plant Operation . . . . . . . . . . . . . . . 2-19 , 2.5 LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . 2-21 1 1 1 l l l l i l l i 2-1
.r - i, ,
d LIST OF FIGURES PAGE 2-1. Water quality sampling stations . . . . . . . . . . . . . . . . . 2-1 2-2. Surface and bottom temperature ('C) at nearfield Station P2, monthly means and 95% confidence intervals over the preoperational period (1978-1989) and the operational period (1991-1992), and monthly means of surface and bottom temperature at Stations P2, P5, and P7 in 1992 . . . . . . . . . . 2-4 2 ^. Long-term annual means and 95% confidence intervals of surf ace I and bottom temperatures at Stations P2, PS and P7, 1979-1992 . . . 2-5 2-4. Comparison of monthly averaged continuous temperature ('C) data collected at the surface at discharge (DS) and farfield (T7) stations during commercial operation, August 1990-December 1992 . . . . . . . . . . . . . . . . . . . . . . . . 2-11 2-5. Monthly mean' difference and 95% confidence intervals between surface and bottom temperatures ('C) at Stations P2, PS, and
. P7 for the preoperational period and monthly means for the operational period (1991-1992) and 1992 . . . . . . . . . . . . . . 2-15 2-6. Surface and bottom salinity (ppt) and dissolved oxygen (mg/L) at nearfield Station P2, monthly means and 95% confidence intervals for the preoperational period (1978-1989) and monthly means for the operational period (1991-1992) and 1992 . . . 2-16 2-7. Surface orthophosphate and total phosphorus (pg P/L) at nearfield Station P2, monthly means and 95% confidence <
intervals for the preoperational period (1978-1984 and 1987-1989), and monthly means for the operational period (1991-1992) and 1992 . . . . . . . . . . . . . . . . . . . . . . 2-18 l 2-8. Surface nitrite-nitrogen, nitrate-nitrogen and ammonia-nitrogen 1 (pg N/L) at nearfield Station P2, monthly means and 95% , l confidence intervals for the preoperational period (1978-1984 and 1987-1989), and monthly means for the operational period (1991-1992) and 1992 . . . . . . . . . . . . . . . . . . . . 2-20 .] t l l 1 l l l 2-11 1 9- edMii . rm.pg e q 9 m - -,--se
. . . -. - ~ . - . .. . . . - =
l
~
l l i i LIST OF TABLES
)
1 1 PAGE ! I l .- 1. MEANS AND 95% CONFIDENCE INTERVALS FOR WATER QUALITY PARAMETERS MEASURED DURING PLANKTON CRUISES AT STATIONS P2, PS, AND P7 OVER PRE 0PERATIONAL YEARS AND MEANS OVER ! OPERATIONAL YEARS (1991-1992) AND IN 1992 . . . . . . . . . . . . 2-6 2-2. RESULTS OF ANALYSIS OF VARIANCE COMPARING WATER QUALITY ! CHARACTERISTICS AMONG STATIONS P2, PS, AND P7 DURING RECENT PREOPERATIONAL YEARS (1987-1989) AND OPERATIONAL (1991-1992) YEARS . . . . . , . . . . . . . . . . . . . . . . . 2-8 2-3. MONTHLY MEAN TEMPERATURES ('C) AND TEMPERATURE DIFFEREN-CES (AT,'C) BE'IVEEN DISCHARGE (DS) AND FARFIELD (T7) STATIONS AT THE SURFACE, AND NEARFIELD (ID) AND FARFIELD (T7) STATIONS AT SURFACE, MID-DEPTH (8.5 m) AND B01 TOM (16 2 m) DEPTHS COLLECTED FROM CONTINUOUSLY-MONITORED TEMPERATURE SENSORS, JULY 1990-DECEMBER 1992 . . . . . . . 2-12 2-4.
SUMMARY
OF POTENTIAL EFFECTS OF SEABROOK STATION ON WATER QUALITY PARAMETERS . . . . . . . . . . . . . . . . . . 2-21 i 2-111
l i l ' WATER QUALITY 2.0 WATER QUALITY 2.2 MET 110DS
2.1 INTRODUCTION
2.2.1 Field Methods Mater quality parameters are coll ** d Near-surface (-1 m) water samples for to provide information on the physical nutrient analysis were collected during environment within the vicinity of daylight hours, utilizing a General Seabrook Station, to interpret information Oceanics* 8-L water sampler from the intake from the biological monitoring program, (Station P2), discharge (PS), and farfield and to determine if the operation of (P7) sampling locations (Figure 2-1). Seabrook Station has had any measurable Nutrient sampling commenced at Stations effect on the physical and chemical P2 and PS in 1978 and at Station P7 in characteristics of the water column. 1982. Sampling continued until 1981 at These objectives are accomplished by PS and 1984 at P2 and P7. Sampling identifying seasonal and annual trends in resumed at all three stations in July temperature, dissolved oxygen, salinity, 1986, and has continued ;.o the present. and nutrient levels at nearfield and Water samples were taken once in January, farfield sampling locations. February, and December and twice monthly N RTE MGR
+
5 HEAD C. 0 5 t Neutas! We .
. , n,-... ? '^fner l SCALE 1
* %??as"" !
I GREAT BOARS HEAD , Hk N r- ,, I s -
. 17 .
sROWW$ k \ , RTVER , 5 , l '* **ol.ga.r . - W ..: OUTERp},l f ""gfgf l SEARROOK^b s / go STATION ,- n f , .fA , LEGEND S $O0K SUNK l - h a = =ater quatiry stations
' \ stAsRoot stAcH gf '
l Figure 2-1. Water quality sampling stations. Seabrook Operational Report,1992. 2-1
- - - . . . . . . - - . _ . - - . ~ - . - - . ~ .. ..
l I i WATER QUALITY l l
- from March through November in conjunction and Wastes (USEPA 1979) and Standard l with the phytoplaitkton and microzooplank- Methods ( APIIA 1989),
ton sampling, and within 24 hours of the weekly macrozooplankton and ichthyoplank-ton sampling. 2.2.3 Analytical Methods Temperature, dissolved oxygen, and Results from these collection efforts salinity measurements began in 1979 at were used to describe the seasonal, 4 Stations P2 and P5, and in 1982 at Station temporal, and spatial characteristics of P7. Sampling at P2 and P7 has continued the water column within the nearshore to the present, while sampling at PS was waters of f Seabrook Station. Any values interrupted from January 1982 until July that were less than the detection limits 1986. At all stations, temperature and were assigned a value equal to one-half conductivity proflies were taken four of the detection limit for computational times per month January through December purposes. Seasonal trends were analyzed with a Beckman Thermistor Salinometer us ing monthly mean temperatures and (through March 1989) or a YSI (Model 33) dissolved oxygen, salinity, and nutrient S-C-T Meter, within 24 hours of the weekly concentrations. Monthly means for the macrozooplankton and ichthyoplankton sam- preoperational and operational periods pling. were calculated from the monthly means for each year within each period. Monthly Duplicate dissolved oxygen samples were means for 1992 were calculated _ as the also collected at near-surf ace and near- average of all samples taken within a bottom (2 m above bottom), and were fixed given month. In the field with manganous sulfate and alkaline iodide-azide. Additionally, Among year trends were evaluated using continuously-monitored temperature data annual or period (preoperational, opera-from the discharge (Station DS), nearfield tion) means. The annual means of 1992 (ID) and f arfield (T7) areas were collect- collections were calculated as the mean ed and provided by North Atlantic Energy of all observations within the year. The Service Corporation (NAESCO)(Figure 2-1), means of preoperational and operational collections were calculated as means of annual means over all years within each 2.2.2 Laboratory Mohada period, which varied among stations and parameters. The preoperational periods Water quality samples were analyzed for for the different analyses are listed on five plant nutrients: total phosphorus , the appropriate tables and figures; . in-orthophosphate, nitrate, nitrite, and all cases the operational period consists ammonia. These determinations were made of collections from 1991-1992. Collec-using a Technicon Autoanalyzer II system, tions from 1990 were not included in these All analyses were performed according to analyses since the year was divided Era Methods for Chemical Analyses of Water between the preoperational and operational 2-2
l I i WATER QUALITY l periods, and the inclusion of partial turns were warmer than during the preoper- l years in each period would bias the means. ational period in all months except July, 1 August, October, and November. Operational /preoperational and near-field /farfield dif ferences in monthly mean Long-term temperature trends (Figure 2-parameter levels were evaluated using a 3) indicate that 1991 was the warmest year multi-way analysis of variance procedure since 1979 at both nearfield and farfield ( ANOVA), which was designed to specifical- stations, and that a warming trend ly test for potential impacts of plant occurred between 1988-1991. These operation. Class variables included dif ferences are reflected in the preopera-period (Preoperational and Operational, tional and operational mean temperatures Preop-Op), year, month, station, and the (Table 2-1), which indicate that average interaction term Preop-Op X Station. The temperatures for the 1991-1992 period were preoperational period for each analysis warmer than temperatures averaged over all ' was specified as 1987-1989, which was the preoperational years and over recent ! period during which all three stations preoperational years. However,1992 mean i were sampled concurrently (thus maintain- surf ace temperatures were lower than the l ing a balanced model design). These preoperational means but within the 95% i results were evaluated in conjunction with confidence limits, means calculated over all available preoperational years to help distinguish Monthly surf ace temperatures at Stations ! , between rocent trends and long-term PS and P7 followed a seasonal pattern trends, similar to that observed at Station P2 during 1992 (Figure 2-2), and have l exhibited a similar long-term trend I 2.3 ELSULTS (Figure 2-3). Over all years of the j study, average surf ace temperatures have j 2.3.1 Physic _aLfainment been warmer at Station P5 than at Stations 1 P2 and P7 (Table 2-1); these differences Tempar.ninr.n were statistically significant between 1987-1992, regardless of operational l Monthly surf ace temperatures at Station status (Table 2-2). At nearfield and I P2 followed a similar seasonal pattern forfield stations, operational mean during both the preoperationni and surface temperatures (averaged over all operational periods (Figure 2-2). months) were significantly warmer than the i Temperatures were low from January-March, means during recent preoperational years increased steadily from April to their (Table 2-2), primarily due to temperatures peak in August, then decreased through observed during 1991 (Figure 2-3). December. Temperatures observed in 1992 Temperatures observed in 1990 fit within were generally within the 95% confidence this increasing trend. Since preopera-interval of preoperational means during tional-operational differences were all twelve months. Over the operational consistent among the stations (nonsignifi-period as a whole (1991-1992), tempera- cant interaction term, Table 2-2), the 2-3
Surface, Intake Bottom, Intake m- %ma m- %e.r.o a
.......... op,,,o., .......... op ,,o.a
--o-- iw2 --.-- tw2
.c u- ,
,. N', s, 9
w u-y . ', W u l g p,, . T a t;
- s 10 -
i io - < .. - a . u i w l s / '.
. f. o -
y l ' A / H 5- .. s 5- ' g...... , w '
- o iiiiiiiiiiii 0 -" T r i i i i i i i i i i JAN FEB MAA Am MAY AlN Al AUG SEP OCT NOV DEC JAN PES MAR Am MAY U AL AUQ 3EP OCT NOV DEC MONTH MONTH Surface, 1992 Bottom, 1992 m- w. m> m- inw. m
.......... w,,,, n .......... %,,,, g 3 re aa n - - - - - -
resa n u- -), u-l ', G
,!; G w w ll w ,, W u u l
2 - p / ,.:. H go . H 10 ,/ '-s g .,. ' '. ' . , w w i '.', b d
. .i ',',
a l e n ~, e l ,' , i c 5- , 5- ,
~. .,
o o i e i i i i i i i i e i i i i i i i i i i i i i JAN R$ MAR Am MAY JUN A1 AUG SEP OCf NOV DEC JAN R8 MAR APR MAY AJN A1 AUG SEP OCT NOV DEC MONTH MONTH
-1 Figure 2-2, Surface and bottom temperature (*C) at nearfield Station P2, monthly means and 95%
confidence intervals over the preoperational period (1978 1989) and the operational period (1991 1992), and monthly means of surface and bottom temperature at Stations P2, P5, and P7 in 1992. Seabrook Operational Report,1992. 2-4
Surface, Station P2 llottom, Station P2 O, P-
- 10 0 -
g ,g 10.0 - , g -
,, ~ / ~- g .
s w -
~
< / \ --
~ --
e w 6 6 3.o - g $.0 - *
$ s c-S3 i i i i i i i i i i i e i *0 i i i e iiiiiiiiii 79 80 81 82 0 84 45 M 47 f3 89 W 91 92 19 80 81 82 83 84 85 M 87 88 89 90 91 92 YEAR YEAR Surface, Station P5 llottom. Station P5 13.0 - 15.0 -
G._ 9 w 10.0 - , /N g t04-g - ~s u ~
- 4 N 5 g
- - /
5 5 .0-l5.0-0.0 , , , , , , , , , , , , , , a0 , , , , ,,,,,,,,,, 79 80 81 82 0 84 85 56 47 88 89 90 91 92 79 to II 82 0 84 43 86 87 88 89 90 91 92 YEAR- YEAR Surface, Station P7 Ilottom, Station P7 15.0 - 15.0 - G G 10'0 - 10.0 - 5 , /' ~ ,, s ' % 5 - w ,
!w -s / N' __ /~' , & 30-
- 65.0-0 0 e &
EO 6 i i 6 i i i I 6 i i 6 40 ., , , , ,,,,,,,,,, 79 80 81 *20 84 85 M $7 88 89 90 91 92 79 80 41 82 0 84 6 M 87 88 89 90 91 92 YEAR YEAR Figure 2 3. Long tenn annual means and 95% confidence intervals of surface and bottom temperatures at Stations P2, P5 and P7,1979-1992. Scabrook Operational l Report,1992. 2-5 l
\
l
TABLE 2-1. MEANS AND 95% CONFIDENCE INTERVALS FOR WATER QUALITY PARAMETERS MEASURED DURING PLANKTON CRUISES AT STATIONS P2, PS, AND P7 OVER PREOPERATIONAL YEARS AND MEANS OVER OPERATIONAL YEARS (1991-1992) AND IN 1992. SEABROOK OPERATIONAL REPORT, 1992. PREOPERATIONAL ALL YEARS
- RECENT YEARSb OPERATIONAL 1992 PARAMETER LCL i UCL LCL i UCL i i ,
TEMPERA'IURE (*C) Surface P2 8.64 9.13 9.62 8.33 8.99 9.65 9.45 8.88 P5 8.97 9.53 10.09 8.30 9.15 9.99 9.75 9.30 P7 8.27 8.73 9.19 8.04 8.84 9.63 9.28 8.79 Bottom P2 6.68 7.13 7.58 6.13 6.57 7.01 7.64 7,39 P5 6.33 7.05 7.77 6.04 6.65 7.27 7.75 7.49 P7 6.32 6.85 7.38 5.95 6.44 6.93 7.43 7.08 w
& SALINITY (ppt)
Surface P2 31.30 31.59 31.87 30.69 31.57 32.44 30.88 30.53 P5 31 31 31.61 31.91 30.67 31.50 32.33 30.76 30.41 P7 31.17 31.53 31.89 30.58 31.39 32.20 30.83 30.55 Bottom i P2 31.99 32.18 32.37 31.32 32.07 32.82 31.23 30.89 P5 31.99 32.18 32.37 31.56 32.13 32.70 31.27 30.86 P7 32.01 32.23 32.45 31.52 32.18 32.83 31.49 31.11 DISSOLVED OXYGEN (mg/L) , Surface P2 9.48 9.69 9.89 9.48 9.71 9.95 9.60 9.69
- P5 9.31 9.71 10.11 9.49 9.73 9.96 9.66 9.77 P7 9.58 9.66 9 73 9.39 9.70 10.00 9.56 9.66 ,
Bottom P2 9.81 9.19 9.48 8.26 9.22 10.19 9.19 9.48 P5 8.71 9.21 9.71 8.19 9.20 10.22 9.27 9.49 P7 8.90 9.09 9.28 8.12 9.12 10.11 9.13 9.34 l (continued)
TABLE 2-1. (Continued) PREOPERATIONAL ALL YEARS
- RECENT YEARSb OPERATIONAL 1992 PARAMETER LCL i UCL LCL i UCL x x SURFACE NUTRIENTS (pg/L)
Orthophosphate P2 10.41 12.95 15.49 9.48 14.91 20.34 13.81 14.05 P5 19.56 12.10 14.64 10.15 14.57 18.99 13.85 13.02 P7 14.21 15.91 17.61 11.17 15.57 19.96 14.38 14.24 Total Phosphorus P2 22.37 25.84 29.31 20.61 29.18 37.75 26.55 24.52 P5 21.73 27.46 33.18 25.37 29.72 34.08 26.43 22.86 P7 25.38 29.11 32.85 20.83 30.97 41.10 26.81 24.10 7 Nitrite " P2 1.60 2.05 2.50 1.23 2.05 2.88 2.17 2.38 PS 1.63 2.14 2.66 1.30 1.96 2.63 1.87 1.74 P7 1.26 1.90 2.55 1.23 2.17 3.12 2.29 2.38 Nitrate P2 34.03 40.00 45.97 17.25 44.03 70.80 37.62 30.95 P5 32.49 39.84 47.18 14.74 42.19 69.63 34.82 23.93 P7 31.28 42.06 52.84 20.99 47.44 73.89 38.93 34.29 A=monia P2 0.28 6.42 12.57 -- -- -- 4.88 2.86 P5 0.00 6.07 19.69 -- -- -- 4.29 3.10 P7 0.00 7.57 20.33 -- -- -- 5.48 3.81 "Mean of annual means for preoperational years: Water quality parameters: P2 = 1979-1989 Nutrients: P2 = 1978-1984, 1987-1989 PS = 1979-1981,-1987-1989 P5 = 1978-1981, 1987-1989 P7 = 1982-1989 P7 = 1982-1984, 1987-1989 b l987-1989; preoperational period specified in ANOVA (Table 2-2), mean of annual means.
*Because analytical methods for ammonia changed in April 1988, preoperational period for a =,nia is April 1988-- December 1989.
. TABLE 2-2. RESULTS OF ANALYSIS OF VARIANCE COMPARING WATER QUALITY CHARACTERISTICS AMONG STATIONS P2, PS, AND P7 DURING RECENT PREOPERATIONAL YEARS (1987-1989) AND OPERATIONAL (1991-1992) YEARS. SEABROOK OPERATIONAL REPORT, 1992. l SOURCE OF MULTIPLE PARAMETER VARIATION
- DF SS F COMPARISONSh <
(ranked in decreasing order) b ,c Surface Temperature PREOP-OP 1 24.16 404.33*** OP> PREOP YEAR (PREOP)d 3 23.08 128.75*** MONTH (YEAR)* 55 4174.19 1270.13*** STATION' 2 4.27 35.71*** P5>P2>P7 PREOP-OP X STATION 8 2 0.23 1.89 NS , ERROR 116 6.93 Bottom Temperature PREOP-OP 1 66.65 773.73*** OP> PREOP YEAR (PREOP) 3 8.10 31.34*** MON'Di (YEAR) 55 1463.23 308.85*** STATION 2 2.07 12.01*** PS>P2>P7 Y PREOP-OP X STATION 2 0.10 0.06 NS ERROH 116 9.99 Surface Salinity PREOP-OP 1 15.88 164.89*** PREOP >0P YEAR (PREOP-OP) 3 23.21 80.34*** MONTH (YEAR) 55 262.55 49.56*** , STATION 2 0.55 2.86 NS PREOP-OP X STATION 2 0.31 1.59 NS - ERROR 116 11.17 Bottom Salinity PREOP-OP 1 27.52 563.60*** PREOP >OP YEAR (PREOP) 3 15.91 108.62*** MONUf (YEAR) 55 70.58 26.28*** STATION 2 1.09 11.16*** P7>PS P2 PREOP-OP X STATION 2 0.17 1.76 NS ERROR 11t> 3.D (continued) _ _ - <r _ _ _ "r- _____.m__- _m _____.___._._..._ :_____ .
TABLE 2-2 (Continued) SOURCE OF MULTIPLE PARAMETER VARIATION
- DF SS F COMPARISONSh (ranked in decreasing order)
Surface Dissolved PREOP-OP 1 1.30 66.44*** PREOP >0.P Oxygen YEAR (PREOP) 3 1.42 24.15*** MONTH (YEAR) 55 159.12 147.50*** < STATION 2 0.13 3.30* PS P2 P7 I PREOP-OP X STATION 2 0.04 1.04 NS ERROR 116 2.28 Bottom Dissolved PREOP-OP 1 0.19 8.72** PREOP >0P Oxygen YEAR (PREOP) 3 15.00 224.96*** , MONTH (YEAR) 55 251.98 206.10*** STATION 2 0.39 8.82*** P5 P2>P7 PREOP-OP X STATION 2 0.07 1.56 NS 4 ERROR 116- 2.58 Orthophosphate PREOP-OP 1 45.22 14.28*** PREOP >0P YEAR (PREOP-OP) 3 245.27 25.81*** MONTH (YEAR) 55 11522.11 66.15*** STATION 2 12.78 2.02 NS PREOP-OP X STATION 2 1.62 0.26 NS ERROR 116 367.38 Total Phosphorus PREOP-OP 1 453.34 16.35*** PREOP >0P YEAR (PREOP-OP) 3 1443.70 17.36*** MONTH (YEAR) 54 18289.25 12.22*** STATION 2 36.82 0.66 NS PREOP-OP X STATION 2 48.78 0.88 NS ERROR 114 3159.96 Nitrate - PREOP-OP 1 3480.33 76.11*** PREOP >0P YEAR (PREOP-OP) 3 13055.58 95.16*** M0tTI'H (YEAR) 55 534683.29 212.58*** STATION. 2 441.57 4.83** P7 P2 PS PREOP-OP X STATION 2 9.28 0.10 NS ERROR 116 5304.73 (continued)
~
TABLE 2-2 (Continued) SOURCE OF MULTIPLE PARAMETER VARIATION
- DP SS F COMPARISONSh (ranked in decreasing order)
Nitrite PREOP-OP 1 0.75 1.93 NS YEAR (PREOP-OP) 3 6.51 5.57** MONTH (YEAR) 55 411.32 19.22*** STATION 2 2.60 3.34* P7 P2 P5 PREOP-OP X STATION 2 0.63 0.80 NS ERROR 116 45.14 Ammonia PREOP-OP 1 98.10 33.58*** PREOP-OP YEAR (PREOP-OP) 2 221.56 37.92*** MONTH (YEAR) 41 567.61 4.74*** e' STATION 2 35.40 6.06** P7>P2 PS PREOP-OP X STATION 2 1.14 0.20 NS Y ERROR 26 251.26 5
- Based on averaged monthly collections for all parameters b
Preoperational years: 1987-1989 at each station for all parameters except ammonia, which was April 1988 through December 1989 Preoperational versus operational period, regardless of station d Year nested within preoperational and operational periods, regardless of station
" Month nested within year nested within preoperational and operational periods, regardless of station
' Station P2 versus PS versus P7, regardless of year 9 Interaction between main effects hunderlining indicates no significant difference when tested with a Waller-Duncan K-ratio e test NS = not significant (p 2 0.05)
* = significant (0.05 2 p>0.01)
** = highly significant (0.01 2 p >0.001)
*** = very highly significant (0.001 2 p)
WATER QUAI.ITY operational status of Seabrook Station and farfield stations and for all three does not appear to-have influenced surf ace combined, operational mean temperatures temperatures in the study area, Signifi- (averaged over all months) were warmer cant differences were also noted smong than preoperational mean temperatures (all years and months (Table 2-2). years and recent years; Tables 2-1 and 2-2). Similar to surface temperatures, Results obtained for bottom temperatures annually-averaged bottom temperatures were similar to results for surface exhibited a warming trend between 1989 and temperatures. Monthly operational end 1991 (Figure 2-3), contributing to the 1992 temperatures were warmer than apparent preoperational-operational preoperational temperatures during several differences. months at Station P2, although ;.Le overall seasonal patterns observed were similar Continuously-monitored temperatures t between the two periods (Figure 2-2). received from NAESCO for 1992 were similar Although all three stations exhibited a to results obtained during routine similar seasonality in 1992 (Figure 2-2), monitoring. A similar seasonal pattern temperatures on average were warmer a'. emerged (Figure 2-4), and surface tempera-Station P5 than at P2 and P7; a similar tures observed in 1992 were cooler than relationship was observed prior to those observed in 1991 (Table 2-3), operation-(Table 2-2) . At both nearfield Stations DS (Discharge) & T7 (Farfield) m m~ ------. v 1A - 16 - h 14 - 'g s s 12 - \ 10 - \ h-Q
\,
s /
'\
\g /.
l \ N H 6- \ / i \
\ , -,/ \ /
4- s u ,- 2-
$0$APO VDC PS A Y e 1 P OCT VDC S A Y O$ POT VEC 1990 1991 1993 Figure 2-4. Comparison of monthly averaged continuous temperature ('C) data collected at the surface at discharge (DS) and farfield (T7) stations during commercial operation.
August 1990-December 1992. Seabmok Operational Report,1992. 2-11 _ - - - . ~,
)
, d E e C u DA 0287 00524 2 3 43 8 8 3 5 8 5 n NF 7 87621 393 4 7 2 0 7 20 5 1 3 i AR . . . . . , . . . .
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)S A - - A - - - - - - - - - - - o S c DT (
(A ES GN 226624699 91 24 7 8 3 4 1 06 1 1 ROD 2 391 2381 66 56 2 381 9 3 827 7 66 AIE . HTR2 9 7 423401 442 - 7 5 9 9 7 4. 2340 111 141 11 7 5 CAO9 9 7 1 1 1 1 1 - 1 T STT9 1 ISI1 D )O N , N7MT 1 2 8 1 5 6 4 1 3 6 ET R 244324 1 1 3 0 8 5 5 2 2 42 E(YO 079959860 03 V LP S 644501 354 - 97 D 4 2 - - 9 1 4 7 5 7DSI ELUP D 1 1 1 1 1 - I - - 1 1 - 1 - BEO IUL
)FNA CRIN *,FATO N I T OT ADCA (N R 61 3221 40397 4 9 0 85 8 8 03 4 08 2 AME 7 23621 4201 66 0 1 1 1 00 1 1 01 1 2 S OP . . . . . . . . . . . . . . .
E)RO T 1 1 1000000011 T 00000 000000 0 CDF A - - - n - - - - - NI K E(DO R EO EDTR FLCB FEEA 1 7 87 10269831 2 4 7 1 1 027 8 8 4 1 IILE 7 1 7327006638 7 1 7 2 27 053 638 DSLS PO 1 9 1 9 7 4436035751 96 7 4 4 36 03 5 65 1 9 6 IAC PE . 9 1 T 1 1 1 1 1 1 9 1 T 1 1 1 1 1 1 UNS2 T H9 ADT9 RNP1 EAE P ,D R 781 931 8667 05 3 4 56 9 8 204 8 6 9 M E 431 948586804 6 2 9 327 1 7 351 5 EE)B . . . . . . . . . . . . . TCmM S 6556034651 1 8 D 4 4 36 0 3 56 5 1 96 A E D 1 1 1 1 1 1 1 I 1 1 1 1 1 1 C DF2.E NR AU6D S1 -
) (0 CE 9
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) 5. SE A 630143
. . A 6 1
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N78 0 7 F - - - - - - 486297 0 7 F - - - - - - 486 29 7 AT(E 9 T R - - - - - - 1 1 1 1 9 T R - - - - - - 1 1 1 1 E( R 9 U 9 U M HU 1 S 1 S DTT ( ( . YLPA LEER D D HIDE L L . TF P E 461 4 41 E 9 1 2787 NRDM I 51 3029 I 6 1 21 33 OAIE F F . . . MFMT R . R S A - - - - - - 486308 D A - - - - - - 4 8639 7 . D - - - - - - 1 1 1 1 1 I - - - - - - 1 1 1 1 _ F F 3 - - 2 E D . G L - E R E L A I B H H H F A T C T R _ T N S N B R R Y N L *G P T V C N A NBRRYNLGFTVC O M I AEAPAUUUECOE DJFMAMJJASOND O M E AEAPAUUUECOE N JFMAMJJASOND _ w < .) : i
TABLE 2-3. (Continued) 1990 1991 1992 MONTH ID T7 AT ID T7 AT ID T7 AT NEARFIELD - FARFIELD (MID-DEPTH) JAN -- -- -- 4.83 5.00 -0.17 4.44 4.70 ~ -0.26 -t FEB -- -- -- 4.19 4.31 -0.12 3.00 -- - - - [ MAR -- -- -- 3.53 3.64 -0.11 3.01 -- -- APR -- -- -- 5.36 5.44 -0.08 4.63 -- -- MAY -- -- -- 8.11 8.39 -0.28 8.12 8.13 -0.01 - JUN -- -- -- 11.19 11.46 -0.27 9.63 9.79 -0.16 , JUL 11.76 11.50 0.26 11.24 11.74 -0.50 10.93 11.31 -0.38 AUG 14.81 15.42 -0.61 14.96 14.88 0.08 12.09 12.39 -0.30 SEP 14.06 13.94 0.12 13.74 13.87 -0.13 11.09 11.40 -0.31 r u OCT 11.92 11.85 0.07 10.94 11.14 -0.20 -- -- --
- d. NOV 9.42 9.53 -0.11 9.41 9.58 -0.17 7.63 7.68 -0.05 DEC 7.47 7.57 -0.11 6.86 7.11 -0.25 5.54 5.83 -0.29 l NEARFIELD - FARFIELD (BOTTOM)
JAN -- -- -- 5.14 5.74 -0.60 4.16 4.34 -0.18 FES -- -- -- 4.19 4.81 -0.62 2.98 3.06 -0.08 MAR -- -- -- 3.39 3.87 -0.48 3.09 3.12 -0.03
-APR -- -- --
4.83 5.13 -0.30 4.29 4.26 0.03 l MAY -- -- -- 6.32 6.67 -0.35 6.19 6.09 0.10 JUN -- -- -- 9.15 9.46 -0.31 8.04 7.96 0.08 ; JUL 9.08 9.62 -0.54 9.01 9.34 -0.33 8.65 8.51 0.14 ! AUG 13.26 13.14 0.12 13.08 12.92 0.16 10.08 9.77 0.31 SEP 12.14 12.31 -0.17 11.89 11.99 -0.10 9.79 9.68 0.11 OCT 11.03 11.17 -0.14 10.28 10.37 -0.09 -- -- -- I NOV 9.49- 9.91 -0.42 9.40 -- -- 8.62 8.83 -0.21 l DEC 7.43 7.96 -0.53 6.93 -- -- 5.76 -- --
- Commercial operation began in August, 1990. _
l I k __..____.._____________1_-.__ _ _ - _ _ . _ _ _ _ . _ _ . - _ - .___ _
.. _. - = . - - . - -- -_- - - - . -
WATER QUAI.ITY l 1
' During the preoperational and operation- preoperational (all years and recent
-al periods, Watet' Column warming began years) and operational periods, mean between February and March at Stations P2 surface salinities were similar among the
- and P5, and between March and April at three stations, but mean bottom salinities Station P7. Fall turnover (the point at were higher at Station P7 than at PS and which bottom temperatures become warmer P2. These relationships were consistent regardless of the operational status of
~ than surface temperatures) occurred at each station during both periods between Seabrook Station (Table 2-2). November and December (Figure 2-5). At each station, the temperature stratifica-tion was weaker (i.e., the difference Ilissolved Oxvnen between surface and bottom temperatures was smaller) in 1992 compared to that Monthly surface dissolved oxygen observed during 1991 (NAI 1992) and the concentrations at Station P2 exhibited a ' preoperational period. Temperature similar seasonal pattern during the stratification observed over the opera- preoperational and operational periods tional period as a whole was weaker than (Figure 2-6). Oxygen concentrations were during the preoperational period at highest from January-March, decreased Stations P2 and P5, but was similar steadily from April through August, were between the two periods at Station P7. stable in September and October, then The weaker stratification observed in 1992 increased in November and December, at Stations P2 and P5 was due primarily Seasonal trends were substantiated by a to cooler surface temperatures and significant difference among months (Table slightly warmer bottom temperatures as 2-2). Monthly operational dissolved comparnd to temperatures from the preoper- oxygen concentrations were lower than ational period. preoperational concentrations during February, March, June, September, October, and November, and were equal' to or
- Salinity slightly greater than preoperational concentrations during the remainder of the Although monthly surface and bottom year. Monthly dissolved oxygen concen-salinities at Station P2 exhibited similar trations observed during 1992 alone were seasonal patterns throughout the study more similar to preoperational concentra-(Figure 2-6), the water column on average tions (Table 2-1).
was less saline during the operational period when compared to the preoperational At all three stations, mean surface period (Table 2-1). Mean surf ace ~ and dissolved oxygen concentrations declined bottom salinities (averaged over all slightly (<0.1 mg/L) but significantly-months) were lower during the operational between the recent preoperational period period in comparison to previous years at and the operational period (Table 2-2), all three stations (Table 2-1). This Over all years of the study, mean surface reduction was significant over the period dissolved oxygen concentrations were not of 1987-1992 (Table 2-2). Over both the significantly different between Stations 2-14 i
.---c.s.,. .- - .w, . - , . .,
. - .. _ - . _ . ~ . ~ ~ . . _ _ - . .. _ ~ _ .-_ . . ~. . .
Station P2 to - p.maca
- 9- .... ..... pm.gg 4- --.o-- 1992 7-
~
.* p
/',sx, ;..q-.~~...
a e-g y s-1- H 1- , d 0- g- VM~~ . , ,
.t -
2 , , , , , , , , , , , , JAN FED MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTII Station P5 to - %,p.n6..i b g- .......... pgg s- --.o-- 3992 g 7-5 j s-
': [f '%
S r'- ,
- o. ,- . . ,. . .
{ 2- , .-' 'u '
&Y 7. . . psf S' '
1-f
'A 1 6 I i i i i i i i . i JAN Fell MAR APR MAY JUN JUI. AUG SIP OCr NOV DEC MONTl!
Station P7 to - e-w.o .i
- 9- .......--*
Wmal k, 8- --*-- 1992 , W 7~ g 6-H 5-h 4-j'%.R, L ' i
\
$ 3- ,
.'h. l 3 2- ,' N, ;
H 1- ',' s - h, r. 70' ~q ~ 2~ i i i i i i i i . . . . JAN ITJi MAR APR MAY JUN JUU AUG SEP OCT NOV DEC J MONTl! I
- Preopentional yern = 1979 1989 b Preoperational yeen = 1979 1981,1987 1989 - !
- Preopentional yesn = 1982 1989
- I Figure 2 5 Monthly mean difference and 95% confidence intervals between surface and bottom temperatures (*C) at Stations P2, P5. and P7 for the pn
- operational period and ,
monthly means for the operational period (1991 1992) and 1992. Seabrook l Operational Report,1992. i 2-15 I i
l Surface 'Sallnity Bottom Salinity i u ws-a u P.,P.au.a
.......... wa .......... y ,a
--4-- i992 --4-- i992 n- n- T o a '
e
/ x E n- .., , $ n- 4 ..
l b 1 h ,, 'a ,.Q,, ,, .., 5,_ /. , ..... .,+ 'q,/h8 3 3
,' r., . ' , ' '.s ,ao a.
p 3o - l s .. .- i
, y c 43o-u b,, , ^d -
a s .. A, , f t/ ,' 'd f
- n. 8- n-3 i e i iiiiiiiii i i i i i i i i i i i i JAN FEB MAR APR MAY EN Et AUG SEP OCTNOV DEC JAN FEB MAR APRMAYEN EL ALU SEP OCrNOVDEC MONTH MONTil Surface Dissolved Oxygen Bottom Dissolved Oxygen ta = 12 -
/ 11 - /9 l g !! -
y g y g p '\ f , f -i .y 3.* *
; 10 - /- ,
; 10 - "
.. A
$ N \,4 A, N.
c ' .. A" 'b*** s l e. 9- T e 9- ,K l ( J j - . .gr. - g ', ' C U '. b
] .
E ,, Prooperadest E g Preoperadma 1
.......... pg ..........
pg
--4-- 1992 --4-- 1992
- I I I I I i a i i i i i 0 i i i i i i i i i a i JAN FEB MAR APRMAY EN EL AUG SEP CCT NOV DEC JAN FEB MAR APRMAY EN Et ALU $EP OCTNOV DEC 'l MONTH MONTH ]
1
.] ,
i Figure 2-6. Surface and bottom salinity (ppt) and dissolved oxygen (mgil.) at nearfield Station P2, monthly means and 95% confidence intervals for the preoperational period (19781989) and monthly means for the operational period (1991 1992) and 1992. Seabrook Operadonal l Report,1992. 2-16 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _3
WATER QUALITY
-P5 and P2, as were concentrations between 2.3.2 Nutrients Stations P2 and P7; concentrations at Station P5, however, were signif1cantly Phoschorus Soccles groater than at P7. The relationship among the three statione with respect to Monthly surface orthophosphate and total surface dissolved oxygen has not changed phosphorus concentrations at Station P2 since Seabrook Station has been operation- generally followed similar seasonal al (nonsignificant interaction term, Table patterns during preoperational and 2-2). operational periods, with some exceptions (Figure 2-7). Operational orthophosphate Results obtained for bottom dissolved concentrations were equal to or greater oxygen concentrations were similar to than the upper 95% confidence limits'of trends in surface dissolved oxygen, preoperational means in March and Septem-although operational concentrations were ber. Operational total phosphorus concen-within the 95% confidence intervals of trations exceeded the upper 95% confidence preoperational mean concent rations during limits of preoperational means in August all twelve months at Station P2 (Figure and December, but were lower than the 2-6). Monthly concentrations observed lower 95% confidence limit of the preoper-during 1992 were greater than the upper ational mean in April. Seasonal differ-95% confidence limit of preoperational ences were substantiated by significant means during April, July, and August, and difforences among months (Table 2-2).
within preoperational confidence intervals Operational mean orthophosphate and total all other months. At each station, the phosphorus concentrations (averaged over average bottom dissolved oxygen concentra- all months) were within the 95% confidence tion observed during 1992 was higher than intervals of preoperational means (all the preoperational mean (Table 2-1). Over years and recent years) at each station all three stations, average concentrations (Table 2-1), although mean operational were slightly but significantly lower concentrations were significantly lower during the operational period when than the recent preoperational means at compared to the recent preoperational all three stations (Table 2-2), period (Table 2-2). Regardless of operational status, average concentrations Average orthophosphate and total were not significantly different between phosphorus concentrations were similar Stations P2 and PS, and significantly among the three stations over the recent i greater than concentrations observed at preoperational period and the operational Station P7. period, Indicating that preoperational-operational dif ferences in orthophosphate and total phosphorus concentrations occurred area-wide.
~! . \
2-17 I
'l
l l Orthophosphate 70 - Pm>pwiumal
.......... op.,. i
--C-- 1992 60 -
M i 30 - M d 40 -
$ l
{ y 30 - a (2 [ .* b l 20 - . .i .
; % *. ]
10 - y g O , , , , , , , , , , , , JAN FEB MAR APR MAY JUN JUI. AUG SEP OCT NOV DEC MONTil Total Phosphorous 70 - %..i ,
..... .... m ,a ,
~
..n. Im I w- ,o I ,
a o: s m- '/ l a a
//
o: i; 2 "O -
..,, - ll l 9
y 30 - k....- N.,
',N L.-
\
S N' # ,' I 20 -
':;;::3% ...:.. .. :ft'--1 l 10 -
c , , , , , , , , , , , , JAN FEB MAR APR MAY JUN JUL AUG SFP OCT NOV DEC MONTil Figure 2 7. Surlace orthophosphate and total phosphorus (pg P/L) at nearfic!d Station P2, monthly means and 95% confidence intervals for the preoperational period (1978 1984 and 19871989), and monthly means for the operational period (1991 1992) and 1992. Seabrook Opemtional Report,1992. 2-18
WATER QUALITY { Nftronen Spiqin P2 and PS or P2 and P7 (Table 2-2). These spatial and temporal differences were Seasonal patterns of nitrogen species consistent regardless of Seabrook during the operational period were similar Station's operational status. l in most cases to trends observed during ! the preoperational period. At Station P2, monthly nitrato concentrations during the 2.4 DISCUSSION operational period were within the 95% confidence intervals of the preoperational 2.4.1 Water Quality Characterization mean during most months (Figure 2-8). Nitrate was generally highest in winter Nearly all water quality parameters (January, February, November, December) showed some significant change between the and lowest in summer (May-September). preoperational and operational periods Significant differences occurred among (Table 2-4) . Temperatures in particular months (Table 2-2). Monthly nitrite were higher over the operational period concentrations at Station P2, however, compared to the preoperational period, showed exaggerated highs and lows, which The apparent increase in temperature did not necessarily correspond temporally during the operational period appears to to preoperational highs and lows. have been caused by the unusually warm Specifically, nitrite concentrations temperatures observed in 1991, as indicat- l observed in 1992 exceeded the upper 95% ed by the long-term trend in annual mean confidence limits of preoperational means surf ace and bottom temperatures. Average in February, March, September snd Decem- temperatures declined in 1992 to levels ber, but were less than the lower 95% that were similar to the preoperational confidence limits of preoperational means means. A similar decline in surface in April, May, and October. Monthly ammo- temperatures between 1991 and 1992 was nia concentrations at Station P2 were less noted elsewhere in the Gulf of Maine than the detection limit in all months in (Maine DMR 1992). Dissolved oxygen 1992 except August, and have generally concentrations, which when tested had a been less than the detection limit since significant inverse relationship to the change in analytical method that temperatures (P=0.001, Pearson Correlation occurred in 1988 (NAI 1992). Coefficient), increased in 1992 in response to these cooler temperatures. Nitrate and ammonia concentrations Other changes included decreases in - averaged over all months declined between salinities and all nutrient concentrations the recent preoperational period and the between the recent preoperational period ' operational period, although nitrite and the operational period, concentrations remained stable (Table 2-2). Concentrations of each parameter were gennrally higher at Station P7 than at P2 2.4.2 Effects of Plant Ooeration and PS (Table 2-1). Differences between P7 and P5 were always significant, and no Although water quality was shown to significant differences were noted between differ between the preoperational and 2-19 i
.- _. . . _ _ _ . . _ _ _ _ _ . __ _ . ~. _ __ ._ - _ . _ . _ . .
Nitrate-NitrogGn
- 2a no wa
- - .o- - im-
, 16o - . e i4o - x i20 - ... w too - ... i gg 80 - w--- *,
,, A .
.a -
- ,f*
vm 6a - - v.. It e- R, " ./1 detection * '
-- a limit 0 i i i i i i i i i i i e JAN FEB MAR APR MAY M EL AtJO SEP OCr NOV- 'DEC MONTH
+ Nitrite-Nitrogen to - Prop numa
% ,a
- --4-- 1992 2 7-
*w E W 6-p A\
o o o~ s 5- p. '
, s e
ma <-
. ., .f.'. . . . , ' Sm i *
\
t.. yg -
/
..*a. \
e 32 '2 2 NUM s, A g, . . .,. i' detection * % i - g;g W %--- ... 6 : - 1, or e(
'e i i i i i i i e i i i JAN FEB MAR APR MAY JUN JUL 'At)O SEP OCr NOV 'DEC MONTH Ammonia Nitrogen b
, 20 - poop. i.a y .
.......... Op.moma jw --o-- 1992 gg o-15 -
ua 10 - 2 c$
. . . . . . . . . . . . ........................ *,-...g...',",........ ...'
r ' ."' detection
- 5-
- umi,
- o. - - -o. - - - o - - - o. - - -o- - - 4, s - - - o - - - c. - - -o 0 i i i 4
i i i i i i i . JAN FEB ~ MAR APR MAY. 2 JUL AUG SEP OCr NOV DEC MONTH 4
- Forthe purpose of calculating monthly means, data points reported as .
*below detection limit
- were given a value of one-half the detection limit.
b ,-. Pisoperational period for ammonia is April 1988. December 1989; confidence intervals not calculated for this period.~ Figum 2 8. Surface nitrite. nitrogen, nitrate. nitrogen and ammonia. nitrogen ( g N/L) at nearfield Station P2, monthly means and 95% confidence intervals for the
. pn: operational period (19781984 and 1987-1989), and monthly means for the operational period (1991 1992) and 1992. Seabrook Operational Report,1992.
2-20
*- _ . . _ . _ -_ .-w- - - , , . . . . .y.,
WATER QUALITY l 1 TABLE 2-4.
SUMMARY
OF POTENTIAL EFFECTS OF SEABROOK STATION ON WATER QUALITY l PARAMETERS. SEADROOK OPERATIONAL REPORT, 1992. ' OPERATIONAL PERIOD SPATIAL TRENDS CONSISTEKr j SIHILAR TO RECENT PRE- WITH PREVIOUS YEARL' 1 PARAMETER DEPTH OPERATIONAL PERIOD?* Temperature surface Op> Preop yes bottom Op> Preop yes Salinity surface Op> Preop yes ) bottom Op> Preop yes I Dissolved oxygen surface Op> Preop yes bottom Op> Preop yes Nitrite surface yes yes Nitrate surface Op< Preop yes Ammonia surface Op< Preop yes Orthophosphate surface Op<Proop yes Total phosphate surface Op< Preop yes I
- based on ANOVA 1987-1992, when all 3 stations were sampled concurrently operational periods, these differences in the study area has been adversely were not restricted to the nearfield area affected by the operation of Seabrook (Table 2-4).
For example, although Station. I temperature has increased over time, it has increased in a similar f ashion at each of the three stations. This suggests the 2.5 LITERATURE CITED presence of a regional warming trend (as indicated by Figure 2-3), rather than an American Public Health Association. 1989. Standard methods for the examination of effect of plant operation. Additionally, water and wastewater, 17th edition. a11 parameters exhibited similar seasonal patterns during the preoperational and Maine Department of Marine Resources. operational periods, suggesting that the 1992. Boothbay Harbor Environmental Data, 1991 and 1992. West Boothbay natural cycling of these parameters Harbor, Maine, remains unaffected by plant operation. At this time, therefore, there are no Normandeau Associates Inc. (NAI). 1992, indications that the physical environment Seabrook Environmental Studies, 1991, 2-21
WATER QUALITY A characterization of environmental conditions in the llampton-Seabrook area during the operation of Seabrook Station. Tech. Rep. XXIII-I. United States Environmental Protection Agency. 1979. Methods for chemical analyses of water and wastes. EPA-600/4-79-020. EMSL, Cincinnati, Ol!. 2-22
TABLE OF CONTENTS PACE 3.0 Pl!YT0 PLANKTON . . . . . . . . . . . . . . . . . . . . . . . . , . . . . 3-1 3.1 OBJECTIVES . . . . . . . . . . . . . . . . . .. . . . . , . 3-1 3.2 MET 110DS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , 3-1 3.2.1 Field Methods . . . . . . . . . . . . . . .. . ... . . 3-1 3.2.2 Laboratory Methods . . . . . . . . . . . . . . . . . . . 3-2 3.2.3 Analytical Methods . . . . . . . . . . . . . . . .. . . . . 3-2 3.3 RESULTS . . . . . . . . . . . . . . . . .. . . . . . . . . . . . 3-5 3.3.1 Total Community . . . . . . . . . . . . . . . . .. . . . 3-5 3.3.1.1 Phytoplankton . . . . . . .. . . . .. . . . 3-5 3.3.1.2 Ultraplankton . . . . . . . . . . . . . . . . . . 3-9 3.3.1.3 Chlorophyll a Concentrations .. . . . . . . . . . 3-11 3.3.2 Selected Species . . . . . . . . . . . . . . . . . . . 3-15 j 3.3.3 PSP Levels . . . . . . . . . . . . . . . . . . . . . . . . 3-15 3.4 DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15 l l 3.4.1 Community Interactions . . . . . . . . . . . . . . . . . . . 3 l 3.4.2 Effects of Plant Operation . . . . . . . . .. . . . . . . 3-18 l l 3.5 LITERATURE CITED . . . . . . . . . . . . . . .. . . . . . . . . . 3-19 1 i I 3-1
~. _ , _ ,
v LIST OF FIGURES PAGE 3-1. Phytoplankton sampling stations . . . . . . . . . . . . . . . . . 3-1 3-2. Monthly mean log (x+1) total abundance (no./1) of phyto-plankton (210 pm) at nearfield Station P2, monthly means and 95% confidence intervals over all preoperational years (1978-1984), and monthly means over operational years (1991-1992); and percent composition by major division for preoperational and operational periods . . . . . . . . . . . . 3-6 3-3. Monthly mean log (x+1) total abundance of ultraplankton (<10 pm) at Station P2, P5 and P7 during 1992 . . . . . . . . . . 3-8 3-4. Mean monthly chlorophyll a concentrations and 95% confidence intervals at Station P2 over preoperational years (1979-1989). and monthly means over operational years (1991-1992); and annual mean chlorophyll a concentrations at Stations P2, P5 , and P7 over early preoperational years (1978-1984), recent preoperational years (1987-1989), and operational years - (1991-1992) . . . . . . . . . . . . . . , . . . . . . . . . . 3-12 3-5. Log (x+1) abundance (no./1) of Skolotonoma costatun at near-field Station P2; monthly means and 95% confidence intervals over all preoperational years (1978-1984) and monthly means for the operational period (1991-1992) and 1992 . . . . . . . . . . 3-13 i 3-6. I,og (x+1) abundance (no./1) of Skeletonoma costetun at t nearfield Station P2; monthly means and 95% confidence intervals over all preoperational years (1978-1984) and monthly means for the operational period (1991-1992) and 1992 . . . 3-16 3-7. Weekly paralytic shellfish poisoning (PSP) toxicity levels e in Nyt11us edu11s in llampton 1(arbor, mean and 95% confidence intervals over'preoperational years (1983-1989) and operational years (1991-1992). Data provided by the State of New flampshire . . . . . . . . . . . . . . . . . . . . . . 3-16 f 3-11
* - 9= - + - -= y _-. y ,
LIST OF TABLES PAGE .3-1.
SUMMARY
OF METil0DS USED IN EVALUATION OF THE PHYTOPLANKTON COMMUNITY . . . . . . . . . . . . . . . . . . . . . . 3-3 < 3-2. ABUNDANCE .(x 10* cells /L) AND PERCENT COMPOSITION OF PIIYT0 PLANKTON SPECIES DURING Tile PREOPERATIONAL PERIOD (1978-84), OPERATIONAL PERIOD (1991-1992), AND 1992, AT NEARFIELD STATION P2 . -. . . . . . . . . . . . . . . . .. . .. . 3-7 3-3. GEOMETRIC MEAN ABUNDANCE (x 10" collo/L) 0F PHYTO-PLANKTON (210pm) AND 95% CONFIDENCE INTERVALS FOR Ti!E PREOPERATIONAL PERIOD, AND OPERATIONAL (1991-1992) AND 1992 GE0 METRIC MEANS . . . . . . . . . . . . . . . . . . . . . 3-9 3-4 RESULTS OF ANALYSIS OF VARIANCE COMPARING ABUNDANCES OF PilYT0 PLANKTON BE1VEEN STATIONS P2 AND P7 DURING PREOPERATIONAL AND OPERATIONAL (1991-1992) PERIODS . .. . .. . . 3-10 , 3-5. 1992 Pl(YTCPLANKTON PERCENT COMPOSITION BY STATION . . . ... . . . 3-10 3-6. GEOMETRIC MEAN ABUNDANCE (x 10* cells /L) 0F ULTRA-PLANKTON (<10pm) AND 95% CONFIDENCE INTERVALS FOR Ti!E PREOPERATIONAL PERIOD, AND OPERATIONAL (1991-1992) AND 1992 GEOMETRIC HEANS . . . . . . . . . . . . . . . . . . . 3-11 3-7. 1992 ULTRAPLANKTON PERCENT COMPOSITION BY STATION . . . . . . . . . 3-12 3 8. RESULTS OF ANALYSIS OF VARIANCE COMPARING ABUNDANCES OF TIIE PilYT0 PLANKTON SELECTED SPECIES AND CilLOROPHYLL a CON-CENTRATIONS AMONG STATIONS P2, PS AND P7 DURING PRE 0PERA- , TIONAL YEARS AND THE OPERATIONAL (1991-1992) PERIOD . . ... . . . 3-14 3-9.
SUMMARY
OF POTENTIAL EFFECTS (BASED ON ANOVA) 0F OPERATION OF SEABROOK STATION ON TifE PilYT0 PLANKTON COMMUNITY , . ... . . . 3-17' r l l 3-111- l l
ti PIIYTOPIANKTON 3.0 PIIYTOPIANKTON 3.2 HETil0DS 3.1 QDJECTIVES 3.2.1 Field Metheda The purpose of the phytoplankton study Near-surface (-1 m) water samples for is to identify seasonal, annual, and phytoplankton and chlorophyll a analyses spatial trends in the primary producer were collected during daylight hours at community in order to determine if the Stations P2 (intake), PS (discharge) and operation of Seabrook Station has had a P7 (farfield) (Figure 3-1) using an 8-measurable effect on the community. liter Niskin bottle. Collections were Specific aspects of the community evaluat- taken once per month in January, February ed include phytoplankton (taxa 210 pm in and December, and twice monthly from March aize) abundance and percent composition, through November at Station P2 from 1978-ultraplankton (taxa < 10 pm in size) 1984, at Station P5 from 1978-1981, and abundance and percent composition, com- at Station P7 from 1982-1984 Chlorophyll munity standing crop as measured by a collections at all three stations chlorophyll a concentrations, abundance resumed in July 1986 and phytoplankton of the selected species (Skoletonema collections were resumed in April 1990, costatum), and toxicity levels of the and have continued on this schedule paralytic shellfish poison (PSP, as through December 1992. From each whole measured by concentrations of Alexandrium water collection, two one quart (0.946 L) camarense, formerly known as Conyaulax jars containing 10 mL of a modified sp. , in the tissue of the mussel Nyc11us Lugol's iodine fixative were filled for edu11s) in the Hampton-Seabrook area, phytoplankton taxonomic analyses and one N ars uoos g d ,y..-. , iTJi B@ HsAD
. . y. C.
. i i o- , 1) . lld8 3CALE
_f
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- . pnyt oi.nuton .i.i.a.
f",' l ,/ @ N ssanoot s . (I . a.
\ suscu ,}~~} 4:i }
Figure 3-1. Phytoplanken sampling stations. Seabrook Operational Report,1992. 3-1
PHYTOPLANKTON I 1 l l l gallon (3.785 L) was reserved for chlo- dances for ultrnplankton, total phyto-rophyll 4 analyses. Wnokly paralytic plankton and thn selected species (Skol- , shn11 fish poisoning (PSP) toxicity lovels econema costatum). The log (x+1) trans- I were provided by the State of New Hamp- formation was performed on the samplo shire. period mean, prior to calculating monthly ) means. Temporal (prooperational-opera- ! < tional) patterns in species abundancos j 3.2.2 Lah2IAlory,4tihnda were evaluated using geometric means; I temporal patterns in community composition Phytoplankton sampics woro prepared for woro evaluated by examining the percent l analysis following the steps outlined in composition of dominant (>1%) taxa. NAl (1991). One randomly-selected Chlorophyll a temporal and seasonal replicato f rom each station and sample comparisons were based on untransformed porlod was analyzed for all taxa and the monthly and yearly mean conenntrations, second replicato was analyzed for Skole- The similarity among the three stations conoma costatun only. Two 0.1-mL sub- with respect to species composition of tho i samples from each replicate were withdrawn dominant phytoplankton taxa was evaluated and placed in Palmer-Maloney nanoplankton statistically using a multivariato counting chambnrs. For those replicates analysis of variance procndure (MANOVA, selected for taxonomic analyses, the Harris 1985). Operational /preoperational I entire contents of the chamber were and nearfield/farfield differences in enumerated and identified to the lowest total abundances for Skolatonema costatun, j practical taxon. phytoplankton, ultraplankton, and mean chlorophyll a concentrations were evaluat-Procedures for preparation of chloro- ed using a multi-way analysis of varianco phyll a water samples are also found in procedure (ANOVA, SAS 1985). Proopera-NAI (1991) . Following the extraction of tional periods for each analysis are ! the plant pigment, fluoresennce was listed on the appropriato figures and determined; chlorophyll a concentrations tables; in all cases the operational (pg/L) worn then computed. porlod evaluated in this report includes collections from 1991-1992. l I 3.2.3 Analytical Methods Weekly mean PSP toxicity levels averaged l over the preoperational and operational Members of the phytoplankton community periods were comparnd graphically. I were classified into two size fractions (ultraplankton [ <10 um] and phytoplankton j [h10 pm]), as defined by Marshall and ' Cohen (1983), and were analyzed separately (Table 3-1) . Seasonal abundance patterns for the prooperational and operational periods woro compared graphically using , log (x+1)-transformed monthly mean abun- l l l 3-2 ,
, --2-w-, -m m, , ,p y , --
w , . -- , - - - w4- -g -
TABLE 3-1.
SUMMARY
OF METHODS USED IN EVALUATION OF THE PHYTOPLANKTON COMMUNITY. SEABROOK OPERATIONAL REPORT, 1992. 1 DATES USED SOURCE OF ANALYSIS TAXON STATIONS IN ANALYSIS DATA CHARACTERISTICS VARIATION PHYTOPLANKTON* Percent Composition All P2 1978-1984; Preoperational and -- 1991-1992 operational means; species with <1% of , total abundance deleted P2,P5,P7 1992 Monthly means; species -- with <1% of total abundance deleted , Abundance All P2,P5,P7 1978-1984; Monthly i; annual -- T 1991-1992 geometric mean; Skeletonema costatum P2 1978-1984; Preoperational and -- 1991-1992 operational means MANOVA 20 dominants P2,P5,P7 1992 Monthly means; species Station
- with <1% of total abundt.nce deleted ANOVA All P2,P7 1982-1984; Monthly i Preop-Op, Year, 1991-1992 Month, Station Skeletonema costatum P2,P7 1982-1984; Monthly i Preop-Op, Year, 1991-1992 _
Month, Station P2,PS 1979-1981; Monthly x Preop-Op, Year, 1991-1992 Month, Station ULTRAPLANKTON* ' l Percent Composition All P2,P5,P7 1992 Monthly i; no deletions -- Abundance All P2,PS,P7 1978-1984; Monthly i; annual -- 1991-1992 geometric mean i (continued) t
. - .__ = .. ._ - _
i 1
- - i TABLE 3-1. -(Continued) 1 DATES USED SOURCE OF.
ANALYSIS TAXON STATIONS IN ANALYSIS DATA CHARACTERISTICS VARIATION i ; CHLOROPHYLL a- ' Concentration -- P2 1979-1989; Monthly i -- 1991-1992 , P2,PS,P7 1978-1984; Preoperational, -- 1987-1989; operational and annual i 1991-1992 means; . ANOVA -- P2,PS,P7 1987-1989; Monthly i Preop-Op, Year, : 1991-1992 Month, Station .
-[ PSP T0XICITY -- --
1983-1989; Weekly i -- 1991-1992
*All data _ log (x+1) transformed I
4 P b b e w
PIIYT0 PLANKTON I 3.3 RESEIS 6mone-Year Trends 3.3.1 Iglal Community On an annualized basis, the phytoplank- 1 ton community at Station P2 has histori- I 3.3.1.1 Ehytonlankton cally been modo up of four major compo- I nents: SAeleconema costatum (Dacillario-3.9A1 Qual Trends phyceae), all other Bacillariophyceae l (diatom) species, Phaeocyst/s pouchecil, Monthly mean total phytoplankton abun- and all remaining species. Although those i dances have typically exhibited a bimodal groupings are descriptive of both the pattern of spring and fall peaks during prooperational and operational periods, I both the prooperational and operational the relativo importance of onch group or periods, as dnpicted by nearfield (P2) species, as well as their actual abundanc-collections (Figure 3-2). Monthly mean es, has varied considerably on a year-to-operational total abundances were slightly year basis (Figure 3-3), grentor than preoperational total abun-dancos in all months except June, July, Diatoms as a group (including Skoloco-August and September, and fell within the nema costatum) comprised approximately 75% upper 95% confidence limit (UCL) of of the preoperational assemblago (531,000 prooporational monthly means in all months organisms /L) ana .53% of the operational except April and December. assemblage (357,200 organisms /L; Table 3- i 2). Skeletonoma costatun alono accounted Although there is seasonal succession for 36% and 21% of the total assemblagos, in the phytoplankton community, diatoms respectively. Within the prooperational i (Bacillarlophyceae) dominated during ton period, however, the relative abundance j of twelve months at Station P2 in both the of Skalotonoma costatus varied f rom as low preoperational and operational porlods, as 10% of the total assemblaga in 1979 to ) accounting for 60-99% of the phytoplankton approximately 80% in 1980 (Figuro 3-3). I assemblago (Figure 3-2). Yellow-green algae (Xanthophycone) have been dominant The remaining diatom species accounted during March and April in the preopera- for 42% (285,700 organisms /L) of tho tional period and in April and May during preoperational assemblage (Tablo 3-2), the operational period. No other groups ranging from 16-17% in 1980 and 1983 to exhibited overall dominance during either 70% in 1979 (Figure 3-3). Species that period, although cryptomonads (Crypto- were important during this period were phycoan) were an important group in May Chaetoceros socialis (10% over the period) (27%) and September (22%) during the and Rhlzosolenta delicatula//ragillsslaa preoperational period. (14% over the period). During the operational period, other diatoms account-ed for 32% (215,900 organisms /L) of the assemblage (68% in 1991 and 26% in 1992); Leptocylindrus danicus and L. minimus were 3-5
Phytoplankton: Total Abundance 6.3 - Prooperiuonal
.......... operigcmag ,O g ['%,
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=0
+w 4.0 =
q ' on 3: ts-2<0 i i i i i i i i i i i i IAN FTB MAR APR MAY AN Jt.1 ALU SEP OCr NOV DEC MONTH Phytoplankton: Preoperational Percent Composition (19781984) 1* - = w m = w m ss m m W We Ws TRR 700: s's s
,, s) ,W< m/// YA W ,,W 'JA ' Y, W,
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i i i i i i i i i i IAN FEB MAR APR htW fdN Et Al'o $EP OCr NOV DEC MONTH Phytoplankton: Operational Percent Composition (19911992) z
'*~ M sW W
A Ws mm We YA W = W W M
,W WNe W
VA M W, M
/A' W
YA We ws sw o so - Ay ;; m ; We yo ,W YA ,W Ay yA 6 m sW ' A'c YA AY We YA mm mm =W eWs Ws ,W ,W NV
,,W VA VA ,W W AY sW VA VA
$, m - sW We Ws tis m :stm: YA ,W Ne VA ,W AY YA
- AV VA' Ws t a tt mtU YA ,W Ne VA ,W AY VA
$ ** AY We YA tit m ,mtU YA ,W We VA ,W AY YA v AY We 's A mm :mit: Ws ,W Wc YA ,WW Nv YA g 20 - sW We 'Ns mm : mt: Ws ,W AY YA sW sW VA We Ws AY Ws tm; : m st: VA ,W = YA f.41 VA
'A'c mm ' ? ? " =i ,/,,'.,' 4mN = '5'15' A 's : ?.4.
i i i i i i i i i i i JAN FEB hMR APR MAY EN Et Atc SEP GCr -NOV DEC MONTH Bacdiariophycea. O ca-r re a . E osr>44 h r. . - cr>vura rc .
@ cru c ycu. G Decchri . E) x.noic y==.
, Figure 3 2. Monthly mean log (x+1) total abundance (no/l) of phytoplankton (210 m) at nearfield Station P2, monthly means and 95% confidence intervals over all preoperational years 1 (1978 1984), and monthly means over operational years (1991 1992); and percent l l
. composition by major division for preoperational and operational periods. Seabrook Operational Repon,1992.
c 3-6
+ - -
TABLE 3-2. ABUNDANCE (x 10* cells /L) AND PERCENT COMPOSITION OF PHYTOPIANITON SPECIES DURING THE PREOPER/.TIONAL PERIOD (1978-1984), OPERATIONAL PERIOD (1991-1992) AND 1992 AT NEARFIEID STATION P2. SEABROOK OPERATIONAL REPORT, 1992. t PREOPERATIONAL OPERATIONAL 1992 PERCENT PERCEhrr PERCEN7 CIASS TAXA ABUNDANCE" COMPOSITION ABUNDANCE
- COMPOSITION ABUNDANCE
- 40MPOSITION Dinophyceae Prorocentrum sicans 0.74 1.08 Cryptophyceae Cryptomonas sp. 1.30 1.95 1.37 1.21 Ianthophyceae Phaeocystis poucbatil 11.80 17.18 27.18 40.68 54.36 47.90 Bac111ariophyceae Baci11ariophyceae 0.78 1.13 1.09 1.63 Ceracaulina bergon11 0.93 1.36 Chaetocetos debills 2.14 3.12 Cheetocaros decipicas 0.11 1.07 Y Chaeroceros socialis 6.58 9.58 1.75 2.61 2.73 2.41 w Chaetoceros sp. 1.21 1,76 2.20 3.29 2.97 2.61 Cy11adrotheca clastorium 0.81 1.21 Eeptocylindrus danicus 3.86 c.77 7.53 6.64 Esprocr11odrus minimus 1.01 1.48 4.70 7.04 7.02 6.18
#f tsschia sp. 3.21 4.67 2.33 3.49 4.25 3.75 Rhizosolenia delicatulaffragilissima 9.45 13.77 1.81 2.71 1.84 1.62 Skeletonesa costatum 24.54 35.74 14.13 21.15 24.81 21.86 Thalassionesa nitzschioides 1.35 1.96 1.09 1.64 1.63 1.44 Thalassiosira sp. 1.91 2.78 1.24 1.86
*Mean abundance over all year (s) in each period; species accounting for
- m 97 $Qp Q% 'y@f M :Mi@s id kk Ni{
- P2>P7 PREOP-0P x STATION
- 1 <0.01 0.03 NS .
- E n a_ , ,.
- includes colonials and filamentous l l
- 1 0.08 0.18 NS Error 57 26.54 "ANOVA based on mean of twice-monthly collections Mar-Nov and monthly collections Dec-Feb; only years when collections at these stations were concurrent are included; analyses include only years when all 12 months were sampled.
- + r s ,o 5 2.0 - %
SUMMARY
OF POTENTIAL EFFECTS (BASED ON ANOVA) 0F OPERATION OF SEABROOK STATION ON THE PHYTOPLANKTON COMMUNITY. SEABROOK OPERATIONAL REPORT,1992. DIFFERENCES BETWEEN OPERA-OPERATIONAL PERIOD TIONAL AND PREOPERATIONAL SIMILAR TO PREOPERATIONAL PERIODS CONSISTENT AMONO COMMUNITY ATTRIBUTE PERIOD 7 STATIONS 7 TOTAL COMMUNITY Op> Preop yes Skeleconess costatum Op> Preop yes Chlorophyll a yes -- 3-17
PHYTOPLANKTON were similar between the two periods, and Androscoggin and/or Kennebec . River (Maine) peak concentrations generally coincided outflows (Franks and Anderson, 1992a). with seasonal peaks in phytoplankton and This theory is consistent with the ultraplankton abundances during both generally observed north-to-south seasonal periods. progression of occurrence of this dino-flagellate and the PSP levels (Franks and The focus of the investigation of the Anderson 1992b). Local sources of ultraplankton assemblage was an examina- dinoflagellates may also contribute to the tion of nearfield-farfield differences blooms as well. However there have not during the operational period, as identi- been PSP " outbreaks" associated solely fication techniques and information avail- with this segment of the New Hampshire ability had significantly improved af ter coast nor have shellfish bed closings in preoperational collections ended in 1984. New Hampshire been conducted independent During 1992, the ultraplankton assemblage of larger regional (southern Maine and was dominated by Cyanophyceae, particular- northern Massachusetts) closings. ly colonials (Table 3-7). Percent composition, seasonal occurrences and total abundances of each of the ultra- 3.4.2 Effects of Plant Oooration plankton taxa were similar among the three stations. Other studies conducted in the Historically (1978-1984), the phyto-Gulf of Maine have indicated that these plankton community has been variable both forms are currently prominent throughout temporally and spatially. The high the region (Shapiro and Haugen 1988; variability in density levels and communi-Haugen 1991). ty structure from year to year due to the influence of both physical and chemical Only minor occurrences of PSP toxicity factors, some cyclical and some transito-have been documented in the study area ry, and to the rapid turnover rate of during the operational period (May 2 and phytoplankton populations, makes it 9, 1991). The occurrence of PSP toxicity difficult to succinctly describe the long-in this portion of the Gulf of Maine was term temporal community structure (NAI first documented in 1972 (NAI 1985), 1985). However, all documented character-possibly as the result of the transport 1stics of the phytoplankton community in of the PSP-producing dinoflagellate the vicinity of Seabrook Station indicate Alexandrium comarense (formerly called that, although some community changes have Conysulax sp.), from the Bay of Fundy occurred over time, these changes have following Hurricane Carrie. With few occurred at all three stations, and in exceptions, PSP has been recorded sea- some cases (i.e. the apparent increase of sonally in this region of the western Gulf certain Cyanophyceae forms), these changes of Maine ever since, although not always have been widely documented in the Gulf at toxic levels. It is currently thought of Maine. Other measures of the phyto-that Alexandrium camarense blooms are plankton community that are somewhat less trnnsported to this reglen on coastally- variable and more predictable than trapped buoyant plumes de. rived from the abundances, such as chlorophyll a, have 3-18
~PHYTOPLANKTON maintained a stable level and pattern of in the Hampton-Seabrook area, 1975-1984.
occurrence between the recent preopera- Tech. Rep. XVI-II, tional and operational periods. Therefore there is no evidence to suggest that the . 1985. Seabrook Environmental operation of Seabrook Station has had a Studies, 1984. A characterization of measurable or detrimental effect on any baseline conditions in the Hampton-Sea-aspect of the local primary producer brook Area, 1975-1984. Technical Report , community. XVI-II.
. 1991. Seabrook Environmental
! 3.5 LITERATURE CITED Studies. 1990 Data Report. Technical Report XXII-I. Frr.nks , P. J. S . and D. M. Anderson. 1992a. Alongshore transport of a toxic phyto- . 1992. Seabrook Environmental plankton bloom in a buoyant current: Studies, 1991. A characterization of j l l Alexandrlue tomarense in the Gulf of environmental conditions in the Hampton-Maine. Mar. Biol. 112:153-164. Seabrook area during the operation of Seabrook Station. Tech. Rep. XXIII-I. Franks, P.J.S. and D.M. Anderson. 1992b. l Toxic phytoplankton blooms in the . 1993. Seabrook Environmental l southwestern Gulf of Maine: testing Studies. 1992 Data. Unpublished Data hypotheses of physical control using Tables, historical data. Mar. Biol. 112:165-174. SAS Institute Inc. 1985. SAS User's Guide: Statistics, Version 5 edition. Harris, R.J. 1985. A primer of multi- SAS Institute, Inc. Cary, N.C. 956 pp. variate statistics. Academic Press, Orlando. 575 pp. Shapiro, L.P. and E. M. Haugen. 1988. Seasonal distribution and temperature l Haugen, E. 1991. Unpublished phyto- tolerance of Synochococcus in Boothbay plankton data filed with MWRA, Deer Harbor, Maine. Estuar. Coast. Shelf Island offshore outfall monitoring stud- Sci. 26:517:525. ies, 1990. Sokal, R.R., and F.J. Rohlf. 1969. Marshall, H.G. and M.S. Cohen. 1983. Biometry. W.H. Freeman and Co., San Distribution and composition of Francisco. xxi + 776 pp. phytoplankton in northeastern coastal waters of the United States. Estuar. Stockner, J.G. 1988. Phototrophic Coast, and Shelf Sci. 17:119-131. picoplankton: an overview from marine and freshwater ecosystems. Limnol. Normandeau Associates Inc. 1984. Oceanogr. 33:765-775. Seabrook Environmental Studies. A characterization of baseline conditions 3-19
E I
-1 1
I l TABLE OF CONTENTS PAGE 4.0 ZOOPLANKTON . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 4-1 4.1 OBJECTIVEG . . . . . . . . . . . . . . .. . . . . . . . . .. . . 4-1 4.2 METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . 4-1 4.2.1 Field Methods , . . . . . . . . .. . . . . . . . . . . 4-1 4.2.1.1 Microzooplankton . ... . . . . . . . . . . .. . 4-1 4.2.1.2 Bivalve Larvae . . . . . . . . . . . . . ... . 4-2 4.2.1.3 Entrainment . . . . . . . . . . . . . .. . 4-2' 4.2.1.4 Macrozooplankton . . . . . . . . . . . . . . . . 4-2 4.2.2 Laboratory Methods . . . .. .. . . . . . . . .. . 4-3 4.2.2.1 Microzooplankton . . . . . . . . . . . . . 4-3 4.2.2.2 Bivalve Larvae . . . . . . . . . .. . . . . . . 4-3 4.2.2.3 Macrozooplankton . . .. . . . . . . . . . . . . 4-3 4.2.3 Analytical Methods . . . . . .. . . . . . . . . . . . . . . -4 4.2.3.1 Communities . . . . . . . . . . . . . . . . . 4-4 4.2.3.2 Selected Species . .. . . . . . . . . . . .. . 4-7 4.3 RESULTS . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 4-8 4.3.1 Microzooplankton . . . . . . . . . . . . . . . . . . . . . 4-8 4.3.1.1 Community Structure . . . . . . . . . . . .. . . . 4-8 4.3.1.2 Selected Species . . . . . . . . . . . . . . . 4-12 4.3.2 Bivalve Larvae . . . . . . . . . . . . . . . . . . . . . 4-18 4.3.2.1 Community Structure . . . . . . . . . . . . . . . . 4-18 4.3.2.2 Selected Species . . . . . . . . . . . . . . 4-23 4.3.2.3 Entrainment . . . . . .. . . . . . . . . . . . . 4-25 4.3.3 Macrozooplankton . . . . .. . . . . . . . . . . . .. . 4-27 4.3.3,1 Community Structure . . . . . . . . . . .. . . 4-27 4.3.3.2 Selected Species . . . . . . . . . . . . . .. . . 4-37 4.4 DISCUSSION . . . . . . . . . . . . . . . . . . . . . . .. . . . 4-43 4.4.1 COMMUNITY . . . . . . . . .. . . . . . . .. . . . . . . 4-43 4.4.2 SELECTED SPECIES . . . . . . . .. .. . . . . . . . .. . 4 4.5 LITERATURE CITED . . . . . . . .. . . . . . . . . . . . . .. 4-49 4-1
LIST OF FIGURES PAGE 4-1. Plankton, water quality and entrainment sampling stations . . . . . 4-1 4-2. Dendrogram and seasonal groups formed by numerical classifi-cation of log (x+1) transformed microzooplankton abundances (no./m3 ) at nearfield Station P2, 1978-1984, July-December 1986, April 1990-December 1992 . . . . . . . . . . . . . . . . . . 4-9 4-3. Log (x+1) abundance (no./m3 ) of Eurytemora sp. copepodites and Eurytemora herdmani adults, Pseudocalanus/Calanus sp. nauplii, and Pseudocalanus sp. copepodites and adults; monthly means and 95% confidence intervals over all preoperational years (1978-1984 and 1986) and monthly means for 1992 and operational period at nearfield Station P2 . . . . . . 4-14 4-4. Log (x+1) abundance (no./m 3
) of Olchona sp. nauplil, copepodites and adults; monthly means and 95% confidence intervals over all preoperational years (1978-1984 and 1986) and monthly means for 1992 and operational period at nearfield Station P2 . . . . . . . . . . . . . . . . . . . . 4-19 4-5. Dendrogram and seasonal groups formed by numerical classifi-cation of bivalve larvae log (x+1) transformed abundances (half monthly means; no./m3) at Seabrook intake (P2), dis-charge (P5) and farfield (P7) stations, April-October, 1988-1992 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-21 3
4-6. Weekly mean log (x+1) abundance (no./m ) of Nycilus edulis larvas during preoperational years (1978-1989, including 957, confidence intervals), and weekly means in the opera-l tional period (1991-1992) and in 1992 . . . . . . . . . . . . . . . 4-24 4-7. Volume of cooling water pumped and number of bivalve larvae (x10') entrained by Seabrook Station, 1990-1992 . . . . . . . . . . 4-26 4-8. Dendrogram and seasonal groups formed by numerical classifi-cation of monthly mean log (x+1) transformed abundances (no./1000 m3 ) of holo- and meroplanktonic species of macro-zooplankton at intake Station P2, discharge. Station P5 and i farfield Station P7, 1988-1992 . . . . . . . . . . . , . . . . . . 4-28 I j 4-9. Dendrogram and seasonal groups formed by numerical classifi-cation of monthly mean log (x+1) transformed abundances (no./1000 m3 ) of tychoplanktonic species of macrozooplankton at intake Station P2, discharge Station P5 and farfield - Station P7, 1988-1992 . . . . . . . . . . . . . . . . . . . . . 4-35 : i 4-11 !- 3
PAGE 4-10. Log (x+1) abundance (no./1000 m3 ) of Calanus finnarchicus copepodites and adults and Carcinus noenas larvae; monthly means and 95% confidence intervals over all preoperational years (1978-1984, 1986-1989) and monthly means for the operational period (1991-1992) and 1992 at intake Station P2 . . . 4-38 4-11. Log (x+1) abundance (no./1000 m3 ) of Crangon septenspinosa (zona and post larvae) and Neomysis americana (all lifestages); monthly means and 95% confidence intervals over all preopera-tional years (1978-1984, 1986-1989) and monthly means for the operational period (1991-1992) and 1992; and mean percent composition of Neomysis americana lifestages over all preopera-tional years (1978-1984, 1986-1989) and for the operational period (1991-1992) at intake Station P2 . . . . . . . . . . . . . , 4-42 l l 1 1 l l 4-111
LIST OF. TABLES PAGE 4-1.
SUMMARY
OF METHODS USED IN NUMERICAL CLASSIFICATION AND ANALYSIS OF VARIANCE OF ZOOPLANKTON COMMUNITIES, AND ANALYSIS OF VARIANCE OF ZOOPLANKTON SELECTED SPECIES . . . . . . 4-5 3 4-2. GEOMETRIC MEANS OF HICROZ00 PLANKTON ABUNDANCE (NO./m ), 95% CONFIDENCE LIMITS, AND NUMBER OF SAMPLES FOR DOMINANT TAXA OCCURRING IN SEASONAL CLUSTER GROUPS IDENTIFIED BY NUMERICAL-CLASSIFICATION OF COLLECTIONS AT NEARFIELD STATION P2, 1978 - 1985, JULY - DECEMBER 1986, APRIL - DECEMBER 1990, 1991 AND 1992 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10 3 4-3. GE0 METRIC MEANS (N0/m ) AND 95% CONFIDENCE LIMITS FOR PREOPERATIONAL YEARS AND MEANS FOR OPERATIONAL YEARS OF SELECTED MICR0 ZOOPLANKTON SPECIES AT STATIONS P2, PS, AND P7 . . . , , . . . . . . . . . . . . . . . . . . . . . . . . . 4 4-4. RESULTS OF THE ANALYSIS OF VARIANCE OF LOG (X+1) 3 TRANSFORMED DENSITY (NC/m ) 0F SELECTED MICROZ00 PLANKTON SPECIES AMONG PREOPERATIONAL YEARS (1982-1984) AND OPERATIONAL YEARS (1991 AND 1992) AND NEARFIELD (= STATION P2) VS. FARFIELD (= STATION P7) AREAS . . . . . . . . . . 4-16 4-5. GEOMETRIC MEAN ABUNDANCE (No,' / 3m ), 95% CONFIDENCE LIMITS OF DOMINANT TAXA AND NUMBER OF SAMPLES OCCURRING IN SEASONAL GROUPS FORMED BY NUMERICAL CLASSIFICATION OF BIVALVE LARVAE COLLECTIONS AT INTAKE (P2), DISCHARGE (PS) AND FARFIELD (P7) STATIONS, 1988-1992 . . . . . . . . . . . . . . . 4-22 3 4-6. GEOMETRIC NEAN ABUNDANCE (No./m ) AND UPPER AND LOWER 95% CONFIDENCE LIMITS OF NYTIEUS EDUEIS LARVAE AT STATIONS P2, P5 AND P7 DURING PREOPERATIONAL YEARS AND GEOMETRIC MEAN ABUNDANCE DURING TIE OPERATIONAL PERIOD (1991-1992) AND 1992 . . . . . . . . . . . . . . . . . . . . . . 4-24 4-7. REFULTS OF ANALYSIS OF VARIANCE COMPARING INTAKE (P2), DISCHARGE (PS) AND FARFIELD (P7) WEEKLY ABUNDANCES OF NYTIEUS EDUEIS DURING PREOPERATIONAL (1988-1989) AND OPERATIONAL (1991-1992) PERIODS . . . . . . . . . . . . . . . . . 25 4-8. ESTIMATED NUMBER OF' BIVALVE LARVAE (x10') ENTRAINED BY THE COOLING WATER SYSTEM AT SEABROOK STATION FROM THIRD WEEK IN APRIL THROUGH THIRD WEEK OF JUNE 1992 . . . . . . , , . . . 4-27 4-iv
PAGE 3 4-9. GEOMETRIC MEAN ABUNDANCE (No./1000m ) AND 95% CONFIDENCE LIMITS OF DOMINANT I!OLO- AND MER0 PLANKTONIC TAXA ~0CCURRING IN SEASONAL GROUPS FORMED BY NUMERICAL CLASSIFICATION OF MACROZ00 PLANKTON COLLECTIONS (MONTHLY MEANS) AT INTAKE STATION P2, DISCHARGE STATION P5 AND FARFIELD STATION P7, 1988-1992 . . . . . . . . . . . . . . . . . . . . . . . . 4-29 3 4-10. GEOMETRIC MEAN ABUNDANCE (No./1000m ) AND 95% CONFIDENCE LIMITS OF DOMINANT TYC110 PLANKTONIC TAXA OCCURRING IN SEASONAL GROUPS FORMED BY NUMERICAL CLASSIFICATION OF MACROZ00 PLANKTON COLLECTIONS (MONTHLY MEANS) AT INTAKE STATION P2, DISCHARGE STATION P5 AND FARFIELD STATION P7, 1988-1992 . . . . . . . . . . . . . . . . . . . . . . . . 4-33 3 4-11. GEOMETRIC MEAN ABUNDANCE (No./1000 m ) AND UPPER AND LOWER 95% CONFIDENCE LIMITS OF SELECTED MACROZ00 PLANKTON SPECIES AT STATIONS P2, P5, AND P7 DURING PREOPERATIONAL YEARS AND GEOMETRIC MEAN ABUNDANCES IN THE OPERATIONAL YEARS (1991-1992) AND 1992 . . . . . . . . . . . . . . . . . . . 4-39 4-12. RESULTS OF ANALYSIS OF VARIANCE COMPARING ABUNDANCES OF SELECTED MACROZ00 PLANKTON SPECIES FROM STATIONS P2, P5, AND P7 DURING PREOPERATIONAL (1987-1989) AND OPERATIONAL (1991-1992) PERIODS . . . . . . . . . . . . . . . . . . . . 4-40 4-13.
SUMMARY
OF POTENTIAL EFFECTS (BASED ON CLASSIFICATION AND MANOVA RESULTS) 0F OPERATION OF SEABROOK STATION INTAKE ON THE INDICENOUS ZOOPLANKTON C0t!MUNITIES . . . . . . . 4-45 4-14.
SUMMARY
OF POTENTIAL EFFECTS (BASED ON ANOVA RESULTS) 0F OPERATION OF SEABROOK STATION INTAKE ON ABUNDANCES OF SELECTED INDIGENOUS ZOOPLANKTON SPECIES . . . . . 4-48 4-v
1 1 ZOOPIANKTON l 4.0 200PIANKTON 4.2 METHOR.S l 6.1 OBJECTIVES 4.2.1 Field Methods j I Three components of the zooplankton 4.2.1.1 Microzooolankton community, microzooplankton, bivalve larvae and macroznoplankton, were sampled Microzooplankton were sampled twice-caparately to identify seasonal, annual, monthly in March-November and monthly in and spatial trends at both the community December-February at intake (Station P2), and species level. Trends of each discharge (Station PS) and farfield component of the invertebrate plankton (Station P7) areas (Figure 4-1). Sampling were evaluated to determine whether ~ occurred from July to December 1986 and entrainment in Seabrook Station's cooling from April 1990 to December 1992. In system intake has had a measurable ef fect addition, Station P2 was sampled from l on the community or any individual January 1978 to December 1984 and Station I species. Entrainment of bivalve larvae P7 from January 1982 to December 1984. in the plant's cooling water system was Four replicato samples were collected by measured directly, pump at 1 m below the surface and 2 m I I l jy RYELEDGE 3 7 ' uzAo O . o s s Nauvaen uae - l
. -l~;;w
. ; . . , v -
SCALE CONTOUA oEPTH IN METERS LEGEND cREary BpR3 .s = zooplankton stations H. M N se y a hivajve larvac stations
~
21 et = Seabrook Entrainment Station BROWN 3 g P1 3 { intake ***b
'\ e NEA UTEA -[) E SEABROOK STATION
1i
- < l fu, g .,,e,,,,;c ,,y .
HA kttTON SEABROOK ' UNK ' HARBOR OCKS ,,,. l, C E
\
SM8R00K ,, i ' i. DEACH g)' Figure 4-1. Plankton and entrainment sampling stations. Seabrook Operational Report,1992. 4-1
ZOOPLANKTON 1 l l above the bottom at each station. Dis- water pumphouse on-site at Seabrook charge from the pumps was directed into Station from July 1986-June 1987 and June a 0.076-mm mesh plankton net (12 cm 1990-October 1992. Three replicates were diameter) set into a s"pecially-designed collected during each sampling date. stand filled with seawater to within 15 Sampling dates coincided with offshore em of the top of the net. Pumping time bivalve larvae sampling whenever possible. was recorded in order to calculate volume Entrainment sampling was not conducted on filtered based on predetermined pumping several scheduled sampling dates, however, rates. Microzooplankton were rinsed from due to either plant outages or sampling the nets into sample containers after equipment problems. I pumping and were fixed in borax-buffered 3% formalin. Samples were taken using a double barrel collection system. A 0.076-mm mesh plankton net was suspended in a 30 gallon 4.2.1.2 Bivalve Larvae drum which, in turn, was suspended in a 55 gallon drum. Water diverted from the The spatial and temporal distributions cooling water system entered the 55-gallon of 12 species of umboned bivalve larvae drum from the bottom and overflowed the were monitored using a 0.5-m diameter, 30 gallon drum into the plankton net. 0.076-mm mesh net. Samples were collected Af ter passing through the net, the water weekly from mid-April through October at discharged through the bottom of both Hampton Harbor (P1), and at Stations P2, drums. The water supply was adjusted to P5 and P7 (Figure 4-1). Sampling began maintain three to six inches of water at Station P2 in July 1976. Farfield above the plankton not at all times. Four Station P7 was added to the program in of these double drum collectors were 1982, and Station P1 was added in July operated simultaneously. After the water 1986. Samples were collected at Station was drained from the system, the contents - P5 from July-December 1986 and April 1988 of the four nets were consolidated and to the present. Two simultaneous two- placed in one sample jar with 1% buffered-minute oblique tows were taken at each formalin. The volume filtered was station. The volume of water filtered was measured with an in-line flowmeter and recorded with a General Oceanics* flow- averaged approximately 7 3m per replicate. meter. Upon recovery, net contents were preserved with 1-2% borax-buffered formalin (with sugar added to enhance 4. 2.1. 4 Macrozoonlaniton color preservation) and refrigerated. Macrozooplankton were collected from July 1986 to December 1992 at Stations P2, 4.2.1.3 Entrainment P5, and P7 (Figure 4-1). Station P2 was also sampled from January 1978 to December Bivalve larvan entrainment sampling was 1984. Station P7 was also sampled from l conducted up to four times a month by January 1982 to December 1984. I NACSCO personnel within the circulating 4-2
~ +
-_-___________________.m_T
ZOOPLANKTON Macrozooplankton collections were made subsample and then averaged to provide at night four times per month, concurrent mean abundances for each replicate. with ichthyoplankton sampling. On each date, four replicate oblique tows were made with 1-m diameter 0.505-mm mesh nets 4.2.2.2 Bivalve Larvae at each station. The nets were set off the stern and towed for 10 minutes while When the total umboned larvae collected varying the boat speed, causing the net ranged from 1-300, the entire sample was , to sink to approximately 2m off the processed. Samples were split when the bottom and to rise to the surface at least total umboned bivalve larvae count twice during the tow. When nets became exceeded 300 specimens and two subsample clogged due to plankton blooms, tows were fractions were enumerated from each shortened to 5 minutes. The volume sample. Umboned larvae were identified filtered was determined with a General from an established species list and Oceanics* digital flowmeter. Upon enumerated. Subsamples (when present) retrieval, each net was rinsed and the were averaged for each tow, and paired contents preserved in buf fered formalin. tows were averaged to obtain a mean for each week. 4.2.2 Laboratory Methods 4.2.2.3 Macrozoonlankton 4.2.2.1 Hierozooolankton Macrozooplankton were analyzed from Two replicates from each depth and three of the four tows (randomly selected) station on all sample dates were analyzed at each station for two of the four for microzooplankton; the remaining two sampling periods each month (usually replicates were archived and stored as alternating weeks). Copepods were
" contingency" samples. The sample was analyzed by concentrating or diluting the concentrated or diluted to a known volume sample to a known volume from which a that provided an optimal working number subsample of approximately 150 copepods of organisms (ca. 200 per 1-m1 subsample), per 1 ml could be attained. The sample ;
Each sample was agitated with a calibrated was agitated with a Stempel pipette to I bulb pipette to homogeneously distribute homogeneously distribute the contents and i the contents. A 1-m1 subsample was 1 m1 was removed and examined under a I removed, placed in a Sedgwick-Raf ter cell dissecting microscope. Subsampling j and examined under a compound microscope continued until at least 30 of the using magnifications of 40X to 200X. All dominant copepod and 150 total copepods zooplankton taxa present in the subsample were counted. If an even distribution of were counted and identified. Most copepods could not be attained,.the sample l copepods were identified to developmental was serially split using a Folsom plankton stage. Two subsamples were analyzed for splitter. Cyclopoids and copepodites of each replicate. Individual abundances for smaller colored species (which were not l all taxa (no./m ) 3were computed for each efficiently collected in the macrozoo-4-3
l l ZOOPLANKTON l plankton samples) were not included in the 4.2.3 Analytical Methods copepod counts. The lifestage and sex of Calanus finmarchicus were identified. 4.2.3.1 Communities Subsamples were recombined with the sample. Macrozooplankton and bivalve larvae analyses began with the calculation of the To enumerate rarer copepods ( Anomalaura arithmetic mean of replicate samples for opalus, Collgus sp., Candacia armaca, each station during each sampling period. Euchaeca sp. , Harpacticoida, Monstrillidae Sampling period means were log (x+1) and Rhincalanus nasutus) and the remaining tracformed prior to statistical analysis. I macrozooplankton, the sample was placed Replicate surface and bottom micro-in a Folsom plankton splitter and serially zooplankton abundances in each sampling split into fractions that provided counts period were log (x+1) transformed prior of at least 30 individuals of each to any analyses (Table 4-1). dominant macrozooplankton taxon (as defined in NAI 1984). A maximum of 100 The macrozooplankton community comprises ml of settled plankton was analyzed, numerous species that exhibit three basic Macrozooplankton taxa were enumerated by life history strategies. The holoplankton species using a dissecting microscope at species, e.g. copepods, are planktonic magnifications between 6x and 150x. essentially throughout their entire life Selected species (Cancer sp., Carcinus cycle. Meroplankton includes species that maenas, Crangon septemspinosa, and spend a distinct portion of their life Neomysis americana) were identified to cycle in the plankton, _ e. g. larvae of detailed developmental stage (lifestage benthic invertebrates. Species that and/or sex). Splits were recombined upon alternate between association with the completion. substrate and rising into the water column - on a regular basis are called tychoplank-For each sample type, species counts ton, e.g. mysids. Because of these were converted to density by multiplying behavioral differences, as well as large each species' count by the appropriate dif ferences in abundances , macrozooplank-scaling ratio (the proportion of the ton species were categorized into holo / sample analyzed for each particular meroplanktonic species or tychoplanktonic < organism) and dividing by the volume of species prior to statistical analysis. water filtered during field collection. The same types of analyses were performed Microzooplankton and bivalve larvae on each group of species. 3 abundances were reported as no./m ; macrozooplankton abundances were reported Temporal and spatial changes in micro-as no./1000 m . 3 zooplankton, bivalve larvae, and the two components of macrozooplankton community structure were evaluated using numerical classification techniques (Boesch 1977), j This technique forms groups of stations and/or sampling periods based on similari-4-4
TABLE 4-1.
SUMMARY
OF METHODS USED IN NUMERICAL CIASSIFICATION AND MULTIVARIATE ANALYSIS OF VARIANCE OF ZOOPLANKTON COMMUNITIES, AND ANALYSIS OF VARIANCE OF ZOOPLANKTON SELECTED SPECIES. SEABROOK OPERATIONAL REPORT,'1992. SOURCE OF DATES USED VARIATION IN ANALYSIS TAXON LIFESTAGE STATIONS IN ANALYSIS DATA CHARACTERISTICS" (M)ANOVA MICROZ00 PLANKTON Numerial 37 dominants -- P2 1978-1984, i, surf ace and bottom; -- classification 7/86-12/86 species excluded with 4/90-12/92 frequency of occurrence
<25%
MANOVA 27 dominants -- P2 1992 i, surface and bottom; Station, Sample PS species excluded with period P7 frequency of occurrence
<25%
AMOVA Selected species: Eurytemora sp. Cb P2 1982-1984; Monthly mean, surface, Preop-Op, Year, & Euryteeora herdmani A P7 1991-1992 and bottom Month, Station O Pseudocalanus/Calanus N Pseudocalanus sp. C,A Oltbona sp. N,C,A BIVALVE LARVAE Numerical All taxa except -- P2 1988-1992* Half-monthly means -- classification Bivalvia PS calculated from P7 weekly x MANOVA All taxa e;tcept -- P2 1988-1992* Weekly i Preop-Op, Station, Bivalvia P5 Year, Week P7 ANOVA Selected species: -- P2 1988-1992 Weekly i Preop-Op, Station, Mytilus edulis PS Year, Neek P7 c (continued)
b TABLE 4-1. (Continued) SOURCE OF. DATES USED VARIATION IN~ ANALYSIS TAXON LIFESTAGE STATIONS IN ANALYSIS DATA CPARACTERISTICS* (H)ANOVA MACROZOOPLANk"f0N Numerical -- P2 1988-1992* Monthly i. -- classification Tycho: P5 Tychoplankton: used all 22 dominants P7 taxa except Mysidacea ! and Amphipoda. Holo /mero: Holo /mero: deleted-taxa 50 dominants occurring in $5% of sam - ples and general taxa. MANOVA All taxa -- P2 1988-1992* Monthly mean Preop-Op, Station,- P5 Yesr, Month e P7 8 ANOVA Selected species: Calanus finmarchicus C,Ab P2 1988-1992* Monthly x Preop-Op, Station, Cancer sp.d L PS Year, Month Carcinus meanas* L P7 . 'Crangon septenspinosa L Neomysis americana All
*All data log (x+1) transformed unless otherwise noted b
C = copepodite; A = adult; N = navplii; L = larvae i *1990 excluded d ( Cancer spp. discussed in Section 8.0 ! *Carcinus maenas larvae are essentially absent for 7 of 12 months, therefore a peak period _of June-October only j was analyzed. l \' . l
ZOOPLANKTON ty levels calcul.ated for all possible dances of dominant taxa among nearfield combinations of stations /samplingperiods and farfield stations and between the and the species that occur there. The preoperational and operational periods Bray-Curtis similarity index (Clifford and (Table 4-1). Historically, there have Stephenson 1975, Boesch 1977) was used, been few differences in planktonic species Values of the indices ranged from 0 for assemblages among nearfield intake and absolute dissimilarity to 1 for absolute discharge and farfield stations. Continu-similarity, ation of the trend during plant operation would suggest that there were no effects The classification groups were formed of plant operation on these communities. from arithmetic averages by the unweighted Probabilities associated with the Wilks' pair group method (UPGMA: Sneath and Sokal lambda test statistic were reported (SAS 1973). Results were simplified by 1985). , combining the entities based on their similarity levels, determined by both the Densities of bivalve larvae in entrain-within group and between group similarity ment samples were multiplied by the values. Results were presented graphical- month's average daily volume pumped ly by dendrograms, which show the within- through the circulating water system, and group similarity and the similarity levels by the number of days represented by each at which they link to the other groups. sampling date, and then summed within The groups were characterized by the mean month to estimate the number of bivalve abundance of dominant taxa and total larvae entrained by Seabrook Station on abundance (sum of all taxa) during the a monthly basis. No entrainment estimates preoperational and operational periods. were made for the August-November 1991 or Communities during the operational period September-October 1992 periods, when. (August 1990-December 1992) were judged sampling was suspended due to scheduled to be similar to previous years if plant outage. collections were placed in the group with the majority of seasonal collections from previous years. A potential impact was 4.2.3.2 Selected Species suggested if community differences occurred solely during the operational Temporal and spatial differences for the period and were restricted to the near- selected species were quantitatively field area. This situation would initiate evaluated for the preoperational and , additional investigations. If community operational periods. Many of the selected l differences occurred at both nearfield and species monitored in the Hampton-Seabrook farfield stations, they were assumed to area have shown year-to-year differences i be part of an area-wide trend, and that are part of natural environmental ; unrelated to plant operation. variability. Given this framework, values from the operational period (1991,1992, l Multivariate analysis of variance and in some cases 1990) were compared to (MANOVA, Harris 1985) was used to assess previous years using analysis of variance - simultaneously the similarity in abun- (Table 4-1). In order to facilitate 4-7
l ZOOPLANKTON 1 interpretation of ANOVA results, the abundance and the dominance structure of j preoperational mean and 95% confidence numerically-important taxa. Lifestages limits, and 1992 and operational annual of the copepods Olchona sp. and means are presented for each selected Pseudocalanus sp., and. Pseudo-sp ecies by station. Most of the organisms calanus/Calanus nauplii were the most show seasonal patterns as well. Some abundant organisms in virtually every species are present only during part of seasonal group during both preoperational the year (e.g., Carcinus maenas), and operational periods (Table 4-2). Therefore, the ANOVA utilized collections Winter samples (Group 1) were character-from those " peak periods," which are noted ized by low abundances of Olchona sp. and in results tables (Section 4.3). Seasonal copepod nauplii. Increased numbers of patterns are shown graphically in plots these species marked the appearance of the of the mean and 95% confidence limits over winter / spring assemblage (Group 3). all preoperational years for each month. Spring and spring / summer assemblages Monthly mean values from the operational (Groups 4 and 5, respectively) were-period and 1992 were plotted on the same characterized by the presence of bivalve graph to provide a visual comparison of veliger larvae and increased numbers of their magnitude and seasonality. copepod nauplii, Olthona sp., c.nd life-stages of Pseudocolanus sp. In fall (Group 6), bivalve veligers disappeared, 4.3 RESULTS and numbers of Olchona sp. , Pseudocalanus sp. lifestages, and copepod nauplii 4.3.1 Microzoonlankton decreased. The small winter ' and f all groups (Groups 2 and 7) did not differ 4.3.1.1 Community Structure appreciably from the other collection dates with respect to those taxa that were Icmocral Characteristics numerically important. Temporal variability in species abun- Comparison of the specific dates includ-dances and taxonomic composition of the ed within the major cluster groups indi-nearshore microzooplankton community cated that differences among years wer. (surface and bottom samples averaged) at generally moderate. The most pronounced Station P2 for all pr'3 operational and variation occurred during late summer and operational collections was examined using fall of preoperational years where cluster numerical classification. Collections groups included a number of " outlying were grouped into five ma.,or groups that collections" (i.e., a collection date corresponded with the annual seasonal separated by more than two weeks from the progression of dominant species and two rest of the seasonal group) (Figure 4-2), additional smaller groups (one collection Summer tended to be a period of high date was ungrouped; Figure 4-2). The abundance and diversity partly due to major seasonal patterns in the microzoo- recruitment of meroplankton into the plankton community structure were largely zooplankton coinmunity. These factors defineated by changes 'in both total contributed to variability within each 4-8
wnhin group sirndanty s .- en 4
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J I Fl M i'lM A l J J lA l' S' l 'O lN lD ' MONTil Figure 4-2. Dendrogram and seasonal groups fonned by numerical classification oflog (x+1) transformed microzooplankton abundances (no/m3) at nearfield Station P2,1978 1984, July-December 1986, April 1990-December 1992. Seabrook Operational Report,1992. 4-9
TABLE 4-2. GEOMETRIC MEANS OF MICROZ00 PLANKTON ABUNDANCE (NO./m3
), 95% CONFIDENCE LIMITS, AND 1RIMBER OF SAMPLES FOR. i DOMINANT TAXA OCCURRING IN SEASONAL CLUSTER GROUPS IDENTIFIED BY NUMERICAL CLASSIFICATION OF COLLECTIONS AT NEARFIELD STATION P2, 1978 - 1985, JULY - DECEMBER 1986, APRIL - DECEMBER 1990, 1991 AND 1992. SEABROOK I OPERATIONAL REPORT, 1992.
i DOMINANT
- PREOPERATIONAL PERIOD OPERATIONAL PERIOD GROUP TAXA n LCL MEAN UCL n LCL MEAN UCL i
1 Copepoda nauplii 13 90.4 158 274.0 5 44.6 309 2108.2 Early Winter Oltbona sp. 117.2 252 540.7 101.7 571 3186.6 (0.60/0.57)b Pseudocolanus sp. 39.1 81 165.2 11.8 53 288.8 Pseudocalanus/Calanus nauplii 39.1 81 167.3 4.8 21 79.9 Tintinnidae 20.2 113 610.3 3.2 15 56.4 2 Cirripedia larvae 5 5.2 62 640.0 not represented Winter Copepoda nauplii 23.6 117 561.1 (0.64/0.62) Oltbona sp. 143.1 305 647.4 Polychaeta larvae 4.6 48 438.7
- Pseudocalanus/Calanus nauplii 28.4 137 647.0 c~
A3 Copepoda nauplii 32 387.6 538 747.2 14 552.6 877 1391.1 Uinter/ Spring Oithona sp. 570.0 862 1304.3 1129.3 1678 2493.0 (0.66/0.62) Pseudocalanus sp. 104.3 174 290.6 -- -- -- Pseudocalanus/Calanus nauplii 321.9 491 748.6 82.9 192 422.9 4 Acarria sp. 14 16.5 51 155.0 1 -- 316 -- Spring Bivalvia veliger larvae 237.3 535 1206.0 -- 1 -- (0.68/0.66) Copepoda nauplii 1368.5 2533 4687.6 -- 1361 -- Oirbona sp. 1815.8 3379 6287.2 -- 1224 -- Pseudocalanus sp. 397.3 690 1198.5 -- 592 -- Pseudocolanus/Calanus nauplii 814.1 1518 2828.6 -- 8 -- Rotifera 8.7 66 459.8 -- 419 -- i 5 Bivalvia veliger larvae 63 374.6 592 934.3 19 70.1 168 400.4 Spring / Summer Copepoda nauplii 2126.1 2896 3944.6 2541.2 3527 4895.3 (0.67/0.66) Oirbona sp. 3266.8 4037 4989.3 4631.6 6180 8246.5 Pseudocalanus sp. 543.8 748 1029.0 184.3 352 673.7 Pseudocalanus/Calanus nauplii 1205.5 1581 2074.1 211.2 399 752.3 (continued)
TABLE 4-2. (Continued) DOMINANT
- PREOPERATIONAL PERIOD OPERATIONAL PERIOD GROUP TAXA n LCL MEAN UCL n LCL MEAN UCL 6 Copepoda nauplii 39 499.3 706 997.8 6 326.8 684 1430.4 Fall Ofthona sp. 972.8 1321 1792.6 697.2 1400 2808.6 (0.68/0.66) Pseudocalanus sp. 147.0 220 329.7 147.6 293 579.0 Pseudocalanus/Calanus nauplii 358.2 497 688.5 48.2 179 657.7 Tintinnidae 24.4 63 158.5 44.9' 893 17430.7 7 Bivalvia veliger larvae not represented 5 31.8 142 625.7 Fall Copepoda nauplii 263.1 508 980.2 (0.74/0.66) Ofthona sp. 506.7 1092 2353.9
- Pseudocalanus sp. 36.4 114 352.4 T
e
- taxa comprising >_ 5% of total group abundance in either preoperational or operational period -
bwithin group similarity /between group similarity 4 k D b
. _ _ _ - . - n , m - _ - - _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _
ZOOPLANKTON -l 1 i I season and among years. Collections from not significantly different among the 1990,1991 and 1992 were generally placed three stations when tested with MANOVA into groups containing corresponding dates (p=0.70), as was found in 1990 (NAI 1991) from the preoperational period, although and 1991 (NAI 1992). , some collections from f all 1990 and 1991 with lower-than-typical abundances were identified as a separate group (Group 7). 4.3.1.2 Selected Species Preoperational and operational periods were similar in the rank order of numer- The copepods Pseudocolanus sp. and ically dominant taxa identified from each Olehona sp. were selected for in-depth cluster group (Table 4-2). Differences analysis in the microzooplankton program among groups, in large measure, were because of their dominant roles in the attributed to seasonal variability in the community. Their abundance and low abundances of these dominant taxa. Sea- trophic level make them important members sonal groups identified by numerical of the marine food web throughout the Gulf classification generally encompassed of Maine (Sherman 1966; Tremblay and Roff collection periods with similar tempera- 1983, lJavic 1984, Anderson 1990). The ture regimes, particularly with respect third selected species, Eurycemora hard-to the depth and intensity of the thermo- mani, although not dominant, has been cline (NA1 1985, NAI 1991), reported to be an abundant coastal copepod in the northern region of the western Atlantic (Katona 1971) and as such, may Sostial Patterns be particularly sensitive to perturbations in the local temperature regime. Life-Spatial variation (i.e., among-stations stages of these taxa were identified differences) in the microzooplankton whenever possible to develop an under-community structure was examined separate- standing of the dynamics of population ly for both the preoperational and recruitment cycles. In some' cases, operational periods, with abundances however, the likely presence of congeneric averaged over depth. Historical com- species made it impossible to routinely parisons of total microzooplankton den- identify all lifestages to species level. sities aieraged on a monthly basis revealed no significant differences between Stations P2 and P7 (NAI 1985). Eurvtemora so.
. Although some numerically-important taxa exhibited large differences in rank order Earlier studies indicated that Euryte-or percent composition between stations, mora sp. copepodite and E. herdmani adult their individual abundances were also not populations in Hampton Harbor and the significantly different, and confidence nearfield Station P2 underwent similar intervals of the preoperational and seasonal cycles, but during the spring the operational abundances generally over- estuarine population was much larger than lapped (NAI 1985). Similarly, 1992 the nearfield population (NAI 1978,1979).
abundances of the 27 dominant taxa were These observations suggest that recruit-4-12
. m. _ ,
l ZOOPLANKTON l ment to the coastal population may be sup- detected in E herdmani adult abundances plemenced by the. estuarine population. in either the preoperational or operation-Other sources of recruitment in the spring al years (Figure 4-3). Although annual might be maturation of, and subsequent mean abundances of E. herdmani adults reproduction of, overwintering copepodites during the operational period and 1992 or hatching of diapause (overwintering) were comparable in magnitude to mean eggs (Grice and Marcus 1981, Marcus 1984). densi*.les for the preoperational years (Table 4-3), the mean operational density Eurycesora sp. copepodite monthly mean of E. herdmani adults was found to be densities for the operational period and significantly lower than the recent 1992 failed to exhibit a mid-summer preoperational mean (Table 4-4). However, density peak that was observed in the mean no significant dif ferences were detected of recent preoperational years (1982-1984) between the average densities of nearfield and were well below the preoperational and farfield areas. Significant differ-average density from June through August ences were noted among years and months. (Figure 4-3) . However, mean operational and 1992 densities displayed (1) a late-spring peak that was comparable in Pseudocalanus_u. magnitude to the preoperational mid-summer peak and (2) a late fall peak that was Historically, Pseudocalanus/Calanus sp. comparable to the fall peak in recent nauplii were present year-round at Station preoperational years. The operational and P2 in large numbers (Figure 4-3), and were 1992 annual geometric means for Eurycemora among the numerically-dominant taxa sp. copepodites at Station P2 were below composing the microzooplankton community the overall mean for the recent preopera- in most seasons (Table 4-2). Seasonal tional years (Tables 4-3, 4-4), but were peak abundance occurred during mid-summer within the range of mean values for during preoperat.lonal years, while the individual years (NAr 1991). ANOVA highest densitica during the operational results indicated that Eurytemora sp. period and 1992 were observed during the 1 copepodite abundances during the opera- late-summer. Annual mean densities for tional period were significantly lower the operational period were significantly ! than densities from recent preoperational lower than the recent preoperational mean ; years. Significant dif ferences were also at both stations (Table 4-4). Seasonal ! noted among years and months. Average and among-year differences were substanti-densities at Station P2 were not signifi- ated by significant differences among cantly dif ferent from those at Station P7. years and months. Spatial differences were not statistically significant. j Temporal changes in the abundance of 1 Eurytemora hardmani adults during the Pseudocalanus sp. copepodites and adults operational period and 1992 followed the were also present throughout the year same general seasonal pattern as described during the preoperational period with peak l for Eurycemora sp. copepodites with the abundances occurring in mid-summer (Figure exception that a fall peak was not 4-3). Peak abundances during the opera-1 4-13 j
Eurytemora sp. Eurytemora herdmani Copepodites Adults 4.0 - ggmag 40- p,,op ,,umag
-- - **- - Opersumal
.......... Opereumal 3, -
--4-- 1992 -- - . i,92 y 3.0 - y 3.0-z- z-gi 2.5- g i 15 -
- e. z g g 10- g g 10-
*5i -
*: 9.3 -
87 5 4 / 81 a s /N 40 kgy i i i i i i i i i i N...f.'? (- 40-
.. .a ,
'y....
i i i o i i ii y JAN FEB MARAPRMAYEN Aa, AUG SEP OCTtOYDEC 1AN FEB MARAPRMAYEN Et AUG SEP OCTNOVDEC MONTil MONTil PseudoealanusICalanus Nauplii i 4.0 - 3.5 - P
'd C 3,o -
u / /f -i
/ -
' . T N.
2.5 - -
,,;j # . .' g,,,
g3 10 - . .s,
*O t.5 - 3 ow 3 3 j 1.0 - Freoperanmal g
.......... po.g
---o-- 1992 00 i i i i iiiie i i JAN FEB mR APRMAYEN Et AUG SEP OCrNOV DEC a
MONTH Pseudocalanus sp. Pseudocalanus sp. Copepodites Adults 4.0 - 4.0 - py,,u.a Op., .g
--o-- 1972 U y 3.0- 1 p ..u A d y 3.0-z T e-g i 2.5 - y, , . . . . o p'" '\T 9C 8 I '-
z 7 dv 2.0 - Q' . / s .
% /S 9
i- R ,y 10 - / ca 2 (, 80 4 9 .,/ %,' 1 Pg
- 51.5- i.
* ! t.5 - ? /. V. ',1 6, 1.0 - Preoperaumal i 1.0 - ' p8 Operaama 1992 a5 - 'I(2' i 40 g ; 3 , g i i 3 , , ; , 40 , i g ; , , i;ie ii JAN FEB MARAPRMAY AN Et AUG SdP OCrNOVDEC JAN FEB MARAPRMAYLN Et AUG SEP OCTNOVDEC MONTF. MONTH Figure 4-3. I.ng (x+1) abundance (no.An') of Eurytemora sp. copepodites and Eurytemora herdmani adults, PseudocalanuslCalanus sp. nauplll, and Pseudocalanus sp.
cupepodites and adults; monthly means and 95% confidence intervals over all preoperational years (1978-1984 and 1986) and monthly means for 1992 and emional period at nearfield Station P2, Seabmok Operational Report,1992. 4-14
TABLE 4-3. 3 GEOMETRIC MEANS (N0/m ) AND 95% CONFIDENCE LIMITS FOR PREOPERATIONAL YEARS AND MEANS FOR OPERATIONAL YEARS OF SELECTED MICR0 ZOOPLANKTON SPECIES AT STATIONS P2, P5, AND P7. SEABROOK OPERATIONAL REPORT, 1992. PREOPERATIONAL YEARS
- SPECIES /LIFESTAGE STATION LCL MEAN UCL OP MEANb 1992 MEAN Eurytemora sp. P2 2.1 4 8.1 1 1 copepodites P5 -- -- --
1 1 P7 <0.1 4 45.3 1 2 Eurytemora herdeani P2 0.8 2 4.1 1 1 adults P5 -- -- -- 1 1 P7- <0.1 3 27.9 1 <1 Pseudocalanus/Calanus P2 380.9 593 923.0 151 206 sp. nauplii PS -- -- -- 131 154 P7 88.4 499 2794.3 127 157 i Pseudocalanus sp. P2 144.3 223 343.3 153 152 C copepodites P5 -- -- -- 185 235 P7 30.0 193 1210.0 179 161 Pseudocolanus sp. P2 13.4 23 39.2 15 17 adults PS -- -- -- 17 22 P7 5.9 25 95.2 21 25 Oltbona sp. P2 238.6 465 904.4 544 852 nauplii P5 -- -- -- 586 691 P7 41.8 403 3818.5 511 811 01thona sp. P2 274.6 490 875.5 858 1020 copepodites PS -- -- -- 929 1028 P7 16.3 299 5185.9 706 850 Oltbons sp. P2 59.3 107 192.3 188 278 adults P5 -- -- -- 207 335 P7 5.4 98 1526.5 156 233 "Preoperational years: P2 = 1978-1984, P5 = not sampled, P7 = 1982-1984. Mean of annual means. b Operational years = 1991 and 1992; 1990 not sampled during January through March, data not included. Mean of annual means. m.._____.-______________m - _ -
TABLE 4-4. RESULTS OF THE ANALYSIS OF VARIANCE OF LOG (X+1) TRANSFORMED DENSITY (N0/m ) 0F 3 SELECTED MICROZ00 PLANKTON SPECIES AMONG PREOPERATIONAL YEARS (1982-1984) AND OPERATIONAL YEARS (1991 AND 1992) AND NEARFIELD (= STATION P2) VS. FARFIELD (= STATION P7) AREAS. SEABROOK OPERATIONAL REPORT, 1992. SPECIES / SOURCE OF LIFESTAGE VARIATION
- df SS F HULTIPLE COMPARISONS Eurytemora sp. Preop-Op 1 3.09 11.28*** Preop >0p copepodite Year (Preop-Op) 3 10.22 12.43***
Month (Year) 55 51.13 3.39*** Area 1 0.07 0.26 NS Preop-Op X Area 1 0.20 0.73 NS Error 148 40.57
- 1. . Eurytemore herdmani Preop-Op 1 4.38 21.29*** Preop >Op l adult 3 8.24 13.35***
l - Year Month(Preop)-Op) (Year 55 53.42 4.72*** I
'. Area ~ 1 0.19 0.91 NS m Preop-Op X Area 1 0.15 0.72 NS Error 148 3 G . 4 ',
1 14.68 62.98***- Preop >Op Pseudocalanus/Calanus sp. nauplii Preop Year(-Op Preop-O 3 7.52 10.75*** Month (Year) p) 55 58.42 4.56*** Area 1 0.09 0.38 NS Preop-Op X Arer. 1 0.01 0.05 NS Error- 148 34.49 Pseudocalanus sp. Preop-Op 1 0.36 1.53 NS copepodite Year (Preop-O 3 6.10- 8.56*** Month (Year) p) 55 51.06 3.91*** Area 1 0.01 0.02 NS Preop-Op X Area 1 0.06 0.26 NS Error 148 35.12 Pseudocalanus sp. 1 0.83 . 3.09 NS adult Preop (-Op Year Preop-O 3 7.58 9.46*** Month (Year) p) 55 57.63 3.92*** Area 1 0.28 1.04 NS Preop-Op X Area 1 0.26 0.97 NS Error 148 39.52 (continued) _. - _ _ _ - _ _ _ - _ - _ = _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
TABLE 4-4. (Continued) SPECIES / SOURCE OF LIFESTAGE VARIATION
- df SS F MULTIPLE COMPARISONS.
Oichona sp. Preop-Op 1 0.24 1.40 NS nauplii Year (Preop-Op) 3 14.91 28.75*** Month (Year) 55 45.07 4.74*** Area 1 0.31 1.80 NS Preop-Op X Area 1 0.02 0.13 NS Error 148 25.59 Oithona sp. Preop-Op 1 5.56 40.55*** Op> Preop copepodite Year (Preop-O 3 14.02 34.08*** Month (Year) p) 55 61.02 8.09*** Area 1 0.66 4.81* P2>P7 7 Preop-Op X Area 1 0.01 0.09 NS y Error 148 20.30 Oltbons sp. Preop-Op 1 1.78 10.41** Op> Preop adult 3 17.67 34.39*** Year Month(Preop)-Op) (Year 55 56.92 6.04*** Area 1 0.39 2.30 NS Preop-Op X Area 1 <0.01 0.00 NS Error 148 25.36 NS = Not Significant (P> 0.05)
* = Significant (0.05 2 P >0.01) ** = Highly Significant (0.01 2 P > 0.001) * *** = Very Highly Significant (P 5 0.001)
- Preop-Op = pre-operational period vs. operational period, regardless of area Year (Preop-Op) = year nested within pre-operational and operational periods, regardless of area Month (Year) = month nested within vear Area = nearfield vs. farfield stations Preop-Op X Area = interaction of main effects
ZOOPLANKTON tional period occurred in late summer. operational and 1992 geometric means for The annual mean densities of both copepo- copepodites at Station P2 were consider-dites and adults during the operational ably larger than the mean for the entire period were not significantly different preoperational period (Table 4-3). from the recent preoperational (1982-1984) Operational densities were significantly meau (Table 4-4) . Significant differences larger than those during the recent were noted among years and months, but not preoperational (1982-1984) period, between stations. Differences among years and months were also significant. The density of copepo-dites at Station P2 over all sampling Oltbons so. dates was significantly greater than at Station P7 (Table 4-4). All Olchona sp.11festages were present year-round and together constituted one Fluctuations in seasonal abundance of of the most abundant microzooplankton taxa 01thona sp. adults during the operational throughout the preoperational period period and 1992 were similar to those (Tables 4-2 and 4-3). Nauplii and cope- observed during the preoperational period. podites occurred at similar levels of Geometric mean abundance for adults at abundance, while adults were slightly less Station P2 for the operational years and abundant (Figure 4-4). 1992 were slightly higher than the mean for all preoperational years (Table 4-3). Olehona sp. nauplii densities at Station However, mean operational densities of p2 during the operational period and 1992 Olthona sp. adults were significantly generally exhibited the same seasonal greater than the recent (1982-1984) pattern of abundance as during the preoperational means at both nearfield and preoperational period (Figure 4-4). The farfield stations. Differences among_ annual operational and 1992 geometric years and months were also significant. means for nauplil at Station P2 were high- No significant dif ferences were detected er than the overall (1978-1984) preopera- between stations. tional mean, but were within the 95% confidence limits (Table 4-3). When average operational densities were 4.3.2 Bivalve Larvae compared to the recent preoperational (1982-1984) mean, this dif ference was not 4.3.2.1 Community Structure significant (Table 4-4). Significant dif ferences were noted among years and Patterns of abundance of the umboned months, but not between stations. bivalve larvae assemblage were examined using numerical classification to address Oltbona sp. copepodites also followed the questions of whether there were the same general pattern of seasonal differences among stations (spatial abundances during the operational period patterns) or between the preoperational and 1992 that was evident during the pre- and operational periods (temporal pat-operational period (Figure 4-4). The terns). This aggregation of meroplank-4-18
l l l 4 l 1 l Olthona sp. Olthona sp. Nauptli copepodites 4.0 - 4.0 - A l 3.5 - g .^ p g 3.5 - q /,,c. ,
* < / '
*/T\
- w. 3.0 -
y3
.c 6j %<,[\ r4 - 3.0 -
W;
\
n.. ,w.. , s;ed
+ -
% 1 c E 2.5 - p .
u/.. b 4 % g N, a: T
\
<
- 2.s -
oE 2 l b 3 2.0 - 8 '.$ b 3 2.0- " 41 it ; 4 1.3 - 41.5-8 d *8 1.0 - Wuonal 8:
- 1.0 - g%g
.. ~....-
Opmumal ,
.......... Opernama
- - .o- - IM2 --oa. - IW2 E0 , , , , , , , , , y , , 40 , , , , , , , , , , , , i JAN FEB MAR APRMAYJUN JUL A00 SEP OCrNOVDEC JAN FED MARAPRMAY AJN JUL AUG SEP OCrNOVDEC MONTil MONTil Olthona sp.
Adults 4.0 - Pmipemmal
% .a u- - - .o - - iw2 Ps w ,., 3.0 - q .# a y5 r
$ T ll' . .'s .
. .~.9l .s
<~ 2.5 - - a g8 % *;.42 "' , [.
, . . (- 1 ao 2.0 - .... .... b.
m2
*j
- 8. u-Y..// 'i ':
i aa i.0- i 6 as - 40 , _ , , , , , , , , , , 3 JAN FEB MARAPRMAYJUN JUL AUd SEP OCrNOVDEC MONTil Figure 4 4. Log (x+1) abundance (no./m') of Olthona sp. nauplii, copepodites and adults; monthly means and 95% confidence inteivals over all preoperationa! years (1978 1984 and 1986) and monthly means for 1992 and operational pei!ou at nearfield Station P2. Seabrook Operational Repon.1991. 4-19
ZOOPLANKTON tonic species exhibited strong seasonal p=0.83). Furthermore, there were no patterns that were generally consistent nearfield-farfield differences in com-among years and stations (Figure 4-5). munity structure that were restricted to Mean abundances were grouped seasonally, the operational period (Station X Preop-falling into one of four distinct groups. Op; F=1.45, p=0.09). The seasonal structure of the community reflected recruitment of different taxa as dominants (Table 4-5). Temocral Patterns The bivalve larvae assemblage showed Spatial Patterns predictable seasonal changes that were consistent among years. No unusual Distribution of meraplankton in marine assemblages of bivalve larvae have a waters can be largely related to several occurred during the operation of Seabrook factors - distribution of spawning adults, Station, as evidenced by the classifica-length of larval existence and local tion of all the operational period hydrographic conditions. The dominant collections into groups that occurred pro-bivalve larvac collected in coastal waters operationally (Figure 4-5 and Table 4-5) . of New llampshire are species whose adults Early spring collections (Group 1) were _ are widely distributed along the New Eng- characterized by low densities of Flatella land coastline. Duration of larvae stage sp. The transition to the late spring i is dependent on temperature, but is assemblage (Group 2) was marked by typically up to six weeks. The local increased densities of #1acella sp. along l l hydrography is dominated by tidal and with moderate densities of #ycilus edu11s ! longshore currents (NAI 1980). Stations and Nya truncaca. !!igh densities of N. P2, PS and P7 are located in waters of edu11s and Neceranomia squamula and i similar depth (Figure 4-1) with no moderate densities of Nodfolus modfolus l physical barriers between them. These typified one of the two summer / fall ; conditions tend to homogenize the bivalve assemblages , Group 3. This assemblage was l larvae spatially. It is not unexpected, followed by a period of low-to-moderate then, that there were few occasions when densities of bivalve larvae (Group 4) that species composition at the three stations occurred in July or August. In most differed. suf ficiently to classify any years, a second peak of #. edults and E. station differently than the others sqreamula and N. modlolus led to the (Figure 4-5). During 89% of half-month recurrence of the summer / fall assemblage periods, all three stations were grouped (Group 3) in late summer or fall, which together; nearfield Stations P2 and P5 was often again followed by low to clustered together 94% of the time. moderate densities of larvae (Group 4). Multivariate analysis of variance indi- Thus no single group characterized the cated there were no significant differ- bivalve larvae assemblage from August-ences in the bivalve larvae assemblage October. arrgng the three stations during the years 1968, 1989, 1991 and 1992 (F=0.715, l I 4-20 i l
within sroup 7..... sundanty 3g kNwgggdsd gg;g g@ Group 1. Early Spring 7 no. of :amples MMY$N@
....... twaween srouP sumlan y j ,*,.. .f ,./ f f f
- t0 ::: *.*.*: *
,.,.,. ., ,. j ,.. *
- Group 2. Spring
-0 no. of sampies .,.,..
,. ,..f.,. f.,....
Grcup 3. . Summer / Fall
?;';';';'i';'v'E'v'E' E i
%w%w% % e g g g % % % % % % % %
g #g# g #g 'g g %%%i g#g#g#g#g#g# g'%
%%( )
N# gW% ##%V% ## %' g Group 4
- Summer / Fall
%#g g ##gV%V%y% i g#% %#% % % % % % % Y
% % % % %'%'% % % % Y NN%WNs,'c
.#,',','.' A #t' A# c l i i l i '
O.0 0.2 0.4 0.6 0,8 1.0 BR AY.CURTIS SIMILARITY n_ g '-~ v . v . v s
,. 9;9;9;9'9;Q Xs'.;0 n- .w::.v; y,y,y,y,y,y;,y,y .a gn2 g $;
i
,* **** ....< W ,$,y,y,y,
,y,y,W y p :,..a.
,., w - y,yf - . . y,y
,y,y,, e n_ .w. y,w -
int n- w,y ,y,y, 4 g
.... f. .w . .%,y,y g %
,%, w , , re aroup i n_ 3 ppg "Q: .
$ a.
O croup 2 tm n_ qqp s uW ve
-M g- ,';,-
o EL * @ oroup 3 P2 m/s p . .J. ' N, . ' ' im Ps-pf 3%
$4*
'v.
.* /,
,y, n. ' croup 4 ry, o
- S Vg .v. y e w o h M_ .v. % % % w %'% =
iwa n- i vn .v. N N N % w%' % s s y n !sh .v. sX6X%X6', %f; APR MAY I NN l $1, Abo Ship oCT MoNTil Figure 4-5. Dendrogram and seasonal gmups formed by numerical classification of bivalve .., larvae log (x+1) transformed abundances (half monthly means; no./m2) at Seabmok ! intake (P2), discharge (PS) and farfield (P7) stations, April-October, 1988-1992. Seabrook Operational Report,1992. 4-21 i i i.
TABLE 4-5. GEOMETRIC MEAN ABUNDANCE (No./m 3 ), 95% CONFIDENCE LIMITS OF DOMIh' ANT rt.Xt. AND NUMBER OF SAMPLES OCCURRING IN SEASONAL GROUPS F0EMED BY NUMERICAL CLASSIFICATION OF BIVALVE LARVAE COLLECTIONS AT ItTTAKE (P2), DISCHARGE (PS) AND FARFIELD (P7) STATIONS, 1988-1992. SEABROOK OPERATIONAL REPORT, 19912 GROUP DOMINANT TAXA
- PREOPERATIONAL YEAPS OPERATIONAL YEARS b n LCL i UCL n LCL i UCL 1 Eiatella sp. 18 29.7 43 61.1 6 17.8 55 165.7 Early spring <
(0.63/0.26)* 2 Eiste114 sp. 10 683.7 1372 2750.9 14 495.2 789 1255.8 Late spring Hycilus eduli.s 30.0 97 306.6 2.1 9 32.1 (0.65/0.45) Hya truncata 79.9 163 331.9 7.7 15 29.7 h 3 #rtilus edulis 52 1731.5 2744 4347.4 38 994.6 1620 2038.9 Summer / Fall Referanomia squamula 539.9 904 1513.9 425.3 731 1257.3 (O.70/0.61) 'Hodiolus modiolus 288.6 452 707.4 142.1 238 399.7 Elate 11a sp. 142.2 267 499.8 86.5 159 29 3 . ~. , 4 Seteranomia squamula 19 59.3 104 181.9 38 153.5 213 275.5 Summer / Fall Hodiolus modiolus 21.4 42 81.9 3.8 5 7.4 (0.63/0.61 Hytilus edulis 23.3 37 58.9 45.9 72 112.2
#pa arenaria 6.0 13 25.3 5.9 9 13.5 Spisula solidissies 7.2 13 22.1 9.5 14 20.8 "those taxa contributing 25% of total group abundance in either preoperational or operational period collections ,
bAugust 1990 - October 1992 '
*(within group similarity /between group similarity)
1 1 I ZOOPLANKTON l l The bivalvo larvae assemblage during the both species were examined to evaluate operational period (beginning in August whether there was evidence of impacts 1990) was similar to previous years, induced by operation of Seabrook Station. ) Dansities of all bivalve larvae were low l in 1992. The typical second peak of ' dsnsities in the late summer or fall #va arenarla either did not occur, as for NycIlus edu11s and Modlolus modfolus, or was of This species is discussed in detail in short duration (Eeceranomia squamula) (NAI Section 10.0. 1993). As a result, the low density summer / f all (Group 4) assemblage occurred f rom mid-July through October (Figure 4- # vellus edu11s 5). Abundances of most of the dominants in each seasonal group during the opera- Abundances of #ytilus edu11s peaked in tional period were less than the pre- mid-June at Station P2 during the preoper-operational mean, but within the 95% ational and operational periods and during confidence 11mits. Tha two mussel species 1992, and remained relatively abundant (#. edu11s and N. modlolus) had abundances until the end of the sampling period in during the operational period that were October (Figure 4-6). Abundances had been below the lower 95% confidence limit significantly higher in 1991 than during (Tabic 4-5). Decreased abundances of the preoperational period (NAI 1992), but bivalve larvae were confirmed by results during 1992 were generally less than the of a MANOVA comparing station and opera- lower 95% confidence limit of preopera-tional condition (1988, 1989, 1991 and tional means, particularly from late July 1992). Although 1991 and 1992 abundances through early August and in late September were significantly lar than abundances through early October. However, the 1992 in 1988 and 1989 (F=43.8, pn0.0001), annual peak abundance (in late June) was dif ferences were consistent among stations slightly greater than the upper 95%- (Station X Preop-Op: F=1.45, p=0.09). confidence limit of the preoperational peak. 4.3.2.2 Selected Soecies The annual abundances at each station during 1992 were an order of magnitude Nya arenaria was identified as a lower than abundances observed in 1991, selected species because of the interest which ranged from 260-296/m3 (Table 4-6 in recreational (locally) and commercial and NAI 1992). Because of the lower (regionally) harvesting of adults and the abundances observed during 1992 at both concern that impacts to the larval nearfield and farfield stations, average population could decrease the standing operational abundances at all three stock of harvestable clams. Nyci1us stations were determined to be signifi-edu11s has been the most abundant species cantly less than recent preoperational encountered in bivalve larvae investiga- (1988-1989) abundances (Table 4-7). This . tions. Temporal and spatial patturns of trend was the reverse of that observed in 4-23
I ZOOPLANKTON l Mytilus eilulls 3- rr.opauma
.......... oporm.g o
-o- twa s 4- -.
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3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 i APR MAY JUN JUL AUG SEP OCT NOV MONTHSVEEK l l Figure 4-6. Weekly met.n log (x+1) abundance (no/m') of Afytilus edults larvae during preoperational years (1978 1989, including 95% confidence intervals), and , weekly means in the operational period (1991 1992) and in 1992. Seabrook Operational Report.1992. 3 TABLE 4-6. GE0HETRIC HEAN ABUNDANCE (No./m ) AND UPPER AND LOWER 95% CONFIDENCE LIMITS OF NYTIMS EMLIS LARVAE AT STATIONS P2, PS AND P7 DURING PREOPERATIONAL YEARS AND GE0HETRIC HEAN ABUNDANCE DURING THE OPERATIONAL PERIOD l, (1991-1992) AND 1992. SEABROOK OPERATIONAL REPORT, 1992. PREOPERATIONAL YEARS OPERATIONAL 1992 STATION YEARS LCL i* UCL i* i
.P2 1982-1989 136.6 258.0 486.6 101.8 32.0 P5 1988-1989 21.9 222.3 2179.5 115.0 39.2 P7 1982-1984, 141.9 286.1 575.8 105.4 41.1 1986-1989 "mean of annual means 4-24
)
i 200 PLANKTON TABLE 4-7. RESULTS OF ANALYSIS OF VARIANCE COMPARING UrrAKE (P2), DISC 11ARGE (P5) AND FARFIELD (P7) WEEKLY ABUNDANCES OF #FTILUS ElX1LIS DURING PREOPERATIONAL (1988-1989) AND OPERATIONAL (1991-1992) PERIODS. SEABROOK OPERATIONAL REPORT, 1992. SOURCE OF HULT.IPLE VARIATION df SS F COMPARISONS Preop-Op 1 3.44 29.02*** Preop >0p Station 2 0.08 0.36 NS Year (Preop-Op) 2 51.95 219.27*** Week (Preop X Year) 97 477.76 41.57*** Station X Preop-Op 2 0.33 1.39 NS Error 197 23.34 1991 (NAI 1992) . Station dif ferences were (Figure 4-7) for two reasons: 1) entrain-not significant during the period when ment sampling onded before the peak period collections were made at all three of bivalve larvae abundances (NAI 1993), stations, although differences among years and 2) numbers of most of the dominant and months were significant. Therefore, taxa were lower than average. E14ts11a 1991 (NAI 1992). Station dif ferences were sp. and Nycilus edulis were the most not significant during the period when commonly entrained taxa in 1992 (Table 4-collections were made at all three 8, Figure 4-7), consistent with the typi-stations, although differences among years cal spring assemblages in offshore waters and months were significant. Therefore, (Table 4-5). In 1990 and 1991, Nycilus the changes in the N. edulis population edulis was the most frequently entrained observed during both 1991 and 1992 species (Figure 4-7), reflecting its domi-occurred throughout the study area. nance in the nearshore bivalve larvae assemblage (Table 4-5). #1acolla sp. and Heteranomia squacula were secondary 4.3.2.3 Entr.u.inment dominants in the entrainment collections in 1990 and 1991 (Figure 4-7). The ef fects of operation of Seabrook Station on bivalve larvae are monitored In all years, entrainment was highest primarily through entrainment sampling and in June or July, reflecting the natural secondarily through comparisons of both peak in bivalve larval abundance observed community and species abundance character- nearshore. Entrainment appeared to be istics between the preoperational and substantially lower in 1991 and 1992 than operational periods. The estimated total 1990 (NAI 1991), primarily due to lower number of larvan entrained in the cooling entrainment of Nycilus edulls, #1acella i water system in 1992 is presented in Table sp. and Eccoranonia squacula. 4-8. In 1992, entrainment samples were collected from April through the third week in June. Entrainment estimates were l substantially inwer than previous years 4-25 l
l l l Cooling Water Pumped i m- 1 i Cn d It h "~ RE 50 -
/
es u
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% M-j S=
u a m-85 O E,., 10 - 0 i iiiiiiiiiiiiiiiiiiiiiiii JUN Et AUO SEP OCT NOV DEC JAN FEB MAR APR MAY JUN EL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN 1990 1991 1992 YEAR / MONTH
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not mnpled Th , o i,ii.... ,iiiiiiiiiiiiii RN Et AD, SEP oCT NOV DEC 1AN FEB MAR APR MAY JUN Et AUG SEP OCT NOV DEC 1AN FEB MAR APR MAY JUN 1990 1991 1992 YEA R/ MONTH Figulo 4-7. Volume of cooling water pumped and number of bivalve larvae (x10') entrained by Seabrook Station,19901992. Seabrook Operational Report.1992. . 4-26
ZOOPLANKTON TABLE 4-8. ESTIMATED NUMBER OF BIVALVE LARVAE (x10') ENTRAINED BY THE COOLING WATER SYSTEM AT SEABROOK STATION FROM THIRD WEEK IN APRIL THROUGH THIRD WEEK OF JUNE 1992. SEABROOK OPERATIONAL REPORT, 1992. SPECIES APR HAY JUN. .b Hytilus edu11s 0.1 0.1 121.7 Modiolus modiolus <0.1 0.1 0.1 Placopecten magellanicus 0 0 0.1 Heteranomia squamula <0.1 0.1 6.7 Spisula solidissima 0 0 0 Hya arenaria 0 0 0.2 Hya truncata 0 0.4 0.7 Hlatella sp. 24.4 36.3 129.1 Macoma balthica 0 0 0 , Bivalvia 9.9 0.6 4.0 ! Teredo navalls 0 0 0 Solenidae <0.1 0.3 75.3 TOTAL 34.4 37.9 338.0
- represents three weeks of June only b
equipment failure in June, sampling not resumed 4.3.3 tiacrozoo.plaahinn The Holo- and Heroolankton Assembinec 4.3.3.1 Community Structure The distinct seasonal patterns of the holo- and meroplankton previously observed Historical analysis (1978-1984 and 1986- were again evident when 1992 collections 1989) of the macrozooplankton assemblage were included in the numerical classifica- i at the nearfield Station P2 showed sea- tion (Figure 4-8, Table 4-9). Winter and sonal changes that were greatly influenced early spring (Group 1) collections were by the population dynamics of the dominant dominated by Cirripedia. Copepods (Temora copepods Centropages typicus and Calanus longicornis, Calanus finmarchicus, finmarchicus (NAI 1990). Other taxa, par- Pseudocalanus sp. , Centropages typicus), 1 ticularly meroplanktonic species, exerted and Olkopleura sp. were co-dominants in i short-term influences, especially during Group 1. Two small groupings of preopera-the spring and summer (NAI 1985). Because tional collections occurred in winter and of their lower abundances, seasonal pat- early spring. Tomora longicornis and terns of tychoplanktonic species, e.g., Sagitta elegans dominated in February 1990' mysids, amphipods and cumaceans, were not (Group 2) and Calanus finmarchicus with well documented by numerical classi- Cirripedia dominated March and April fication of the entire macrozooplankton samples in 1989 (Group 3). Late spring assemblage. To identify seasonal patterns (Group 4) collections were dominated by more clearly, the tychoplankton assemblage Calanus finmarchicus, although other was analyzed separately from the moro- and copepods (T. longicornis, C. typicus), the holoplankton. j 4-27
...... within aroup ,
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- JAN l FEB l MAR APR k MAY l NN l NL . AUGl SEP oCT l NoV l DEC Momu 1
Figum 4 8. Dendrogram and seasonal gmups formed by numerical classification of monthly 3 mean log (x+1) transformed abundances (no/1000 m ) of holo. and meroplanktonic species of macmzooplankton at intake Station P2, discharge Station P5 and farfield ; Station P7,1988-1992. Scabrook Operational Report,1992, .; 4 28 l 6 .I l
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TABLE 4-9. 3 GEOMETRIC MEAN ABUNDANCE (No./1000m ) AND 95% CONFIDENCE LIMITS OF DOMINANT Il0LO- AND MER0 PLANKTONIC TAXA OCCURRING IN SEASONAL GROUPS FORMED BY NUMERICAL CLASSIFICATION OF MACROZ00 PLANKTON COLLECTIONS (HONTHLY MEANS) AT INTAKE STATION P2, DISCHARGE STATION PS AND FARFIELD STATION P7, 1988-1992. SEABROOK OPERATIONAL REPORT, 1992. GROUP
- DOMINA}rr SPECIESb PREOPERATIONAL YEARSC OPERATIONAL YEARSc n LCL i UCL n LCL i UCL 1 Cirripedia 12 4290.7 9454 20830.1 21 3286.1 13230 53254.3 Winter-Early Temore longicornis 2199.9 4262 8255.7 1456.7 2438 4079.0 Spring Calanus finmarchicus 1345.2 2889 6204.6 363.8 1290 4564.6 (0.70/0.61) Pseudocalanus sp. 1048.7 2033 3941.3 1414.1 2297 3729.9 Sagitto elegans 436.2 1439 4743.2 370.6 704 1335.0 Oikopleurs sp. 125.,1 697 3864.4 5406.4 11097 22778.5 Centropages typicus 35.4 84 199.6 1874.8 3896 8093.6 2 Temora longicornis 3 3224.5 29586 271404.5 not represented Feb 1990 Sagitta elegans 7109.1 20976 61890.1 (0.81/0.58) 3 Calanus finnarchicus 6 4483.2 8051 14458.9 not represented ,
Mar-Apr 1989 Cirripedia 1051.9 4501 19253.1 (0.68/0.49) 4' Calanus finmarchicus 24 39516.7 57933 84931.5 12 53482.7 111028 230487.9 Late Spring Temora longicornis 3640.7 6173 10467.3 4772.1 8131 13853.8 (O.74/0.66) Evadne sp 3201.3 6113 11670.8 5544.7 11939 25704.8 Eualus pasiolus 3908.0 6056 9384.1 1167.2 2197 4134.7 Centropages typicus 7.1 30 116.2 5263.7 10568 21217.3 5 Calanus finmarchicus 18 17309.3 37401 80812.4 24 16612.3 29202 51322.1 Summer Centropages typicus 8075.7 24997 77371.7 33804.9 76227 171882.6 (0.70/0.66) Cancer sp. 10234.1 24507 58681.4 27110.1 39563 57736.3 Eualus pusiolus 3047.2 7596 18931.5 3126.2 5208 12328.2 Temore longicornis 1789.3 4133 9544.6 6009.8 9636 15449.0 (continued)
TABLE 4-9. (Continued) GROUP" DOMINANT SPECIESb PREOPERATIONAL YEARSC OPERATIONAL YEA'RSC n LCL i UCL n LCL i UCL l 6 Centropages typfcus 12 19923.0 47263 112120.7 21 18280.0 36998 74880.7 i Fall Centropages bamatus 3588.5 6522 11852.1 155.2 426 1167.2 q (0.69/0.66) Centropt.ges sp. 2109.1 5255 13091.0 509.0 1285 3242.8 1 7 Centropages typicus 18 1537.6 2992 5819.8 9 1275.9 2982 6967.5 Late Fall- Temora longicornis 1543.5 2563 4255.0 275.0 556 1124.1 i y Centropages bamatus Early Winter- 833.6 1338 2146.7 4.5 23 104.6 g (0.72/0.66) Pseudocalanus sp. 625.6 1111 1972.0 40.8 87 185.0 Sagitta elegans 590.5 973 1602.1 404.2 702 1227.5 Centropages sp. 382.3 652 1113.2 86.9 236 636.0
*(within group similarity /between group similarity) b those taxa contributing 25% of total group abundance in either preoperational or operational periods
*preoperational period = January 1988-July 1990; operational period = August 1990-December 1992
- - ~ . , , . - _ _ _ . _ _ . _ . _ - - - - . _ . _ _ _ _ . _ - _ - . _ . - - . . - _ . ~ .u-___m-.- .- _-- - - . _ _ _ _ _
ZOOPIANKTON I .cladoceran Evadne sp. and the shrimp P2, P5 and P7 are small relative to the j gualus puslolus' were also abundant, aren from which holo- and meroplanktonic Summer (Group 5) collections were domina- organisms could be recruited (via current ted by C. Ilnmarchicus, C. typicus and transport) to coastal New Hampshire. Cancer sp. Other meroplanktonic species (e.g., Carcinus moonas, Sec. 4.3.3.2), Numerical classification of holo- and though not dominant, reached their peak meroplanktonic abundances in 1988-1992 abundances during summer months. C. typl- revealed no spatial differences among cus, its congener C. hamatus and Cen- Stations P2, PS and P7 (Figure 4-8). tropages sp. copepodites were dominant in Collections from all stations were grouped fall and early winter (Groups 6 and 7). together within each month. Although Early winter (Group 7) abundances were species composition was similar among reduced compared to those in the f all, and stations, differences in species abundanc-other copepods were relatively abundant, es were detected by HANOVA (p=0.0001). Dif ferences in individual species abun-The seasonal shif t in dominance between dances were most likely to occur between Cirripedia, Calanus /inmarch/cus and the farfield and nearfield stations; for Contropages typicus between 1988-1992 was species exhibiting spatial differences, consistent with patterns observed histori- abundances were generally- higher at cally (NAI 1990) . The seasonal shif ts in nearfield stations. This was the case for dominance observed among the copepods Calanus finmarchicus (see also Sec. Calanus /inmarchicus, Centropages typicus 4.3. 3. 2) and Temora longicornis, tuo of and to a lessor extent, Pseudocalanus sp. the three numerically dominant taxa in were consistent with others' observations 1988, 1989, 1991 and 1992. Differences for the Gulf of Maine (Sherman et al. could be related to spatial differences 1988), in water quality parameters. Temperature and dissolved oxygen, for example, were Previous analyses have suggested that higher in the nearfield area than farfield there are no spatial dif ferences in holo- in both near-surface and near-bottom and meroplanktonic assemblages in the waters, while bottom salinity and nitrogen study area (NAI 1991). The geography of nutrients were higher in the farfield coastal New England helps to create the (Section 2.0). hydrographic conditions of the Gulf of Maine. There are no major land barriers Species composition of holo- and mero-between the Bay of Fundy and Cape Cod that planktonic components of the macrozoo-would divert coastal currents offshore, plankton assemblage during the operation although several embayments can affect of Seabrook Station was similar to the local conditions. This condition promotes preoperational period examined. Collec-a circulation pattern that allows wide- tions from each month in the operational spread dispersal of planktonic organisms, period were grouped with collections from particularly holoplankton and those mero- the same month in the preoperational planktonic species with extended larval period except January and December 1992 existence. The distances among Stations (Figure 4-8). Collections from these 4-31 J
1 1 I l ZOOPLANKTON ! months in previous years had formed the one species, Calanus //ncarchicus, which late f all-early winter assemblage (Group was reported to have exhibited an in-7), Due to the presence of Olkopleura creasing trend in the Northwest Atlantic sp. , C41 anus finmarchicus and Cirripedir over the past 30 years (Sherman 1991). larvae, as well as the absence of Centro- Jossi (1991) reported that total copepod pages hamatus, the macrozooplankton assem- abundances in the Gulf of Maine were blage in January 1992 resembled typical higher in 1990 than in the previous winter-early spring (Group 1) biological decade. Only Centropages hamatus declined conditions more closely than Group 7. In in abundance. Sagitta elegans, Pseudo-December 1992, high abundances of the calanus sp., Evadne sp. and Eualus congeneric species C. typicus and C. pusfolus were similar in abundance between hamatus, as well as their copepodites were the two time periods. more typical of fall (Group 6) conditions than of late f all-early winter (Group 7), when abundances tend to be reduced. The Tychoolankton Assemblane l Group abundances were generally similar Abundances of tychoplanktonic species between operational and preoperational tended to vary seasonally over only one-periods with two exceptions. Late fall to-two orders of magnitude; three taxa and early winter (Group 7) abundance was (amphipods Pontogenela inerals and lower in the operational period due mostly Oedicerotidae, and the mysid Neomysis to reduced abundances of copepods Tomore americana) were usually among the domi-longicornis, Centropages hamatus and nants (Table 4-10). Seasonality of the Pseudocolanus sp. Abundances of tychoplankton species assemblage is less Olkopleura sp. and Centropages typicus in clearly defined by numerical- classifica-winter and early spring (Group 1) were tion than are seasonal patterns of the substantially higher during the opera- holo- and meroplankton assemblage. tional period than the preoperational Within-group similarities are lower and period. Geometric mean abundances of between-group dif farences are smaller for dominant taxa were generally higher in the tychoplankton groups (Figure 4-9; Table operational years of 1991-1992 than in the 4-10) than for holo- and meroplankton preoperational period of 1988-1989 (MANOVA groups, as noted in NAI (1992). Apparent testing operational status; p=0.0001). seasonal patterns likely reflect environ-Of the 11 taxa that dominated the holo- mental conditions along with a con.bination and meroplankton during various parts of of other factors: Intermittent swimming the annual cycle, seven (Temora longl- activity, recruitment of new individuals cornis, Centropages typicus, Olkopleura and sampling bias introduced by use of sp., Cirripedia, Calanus Ilnmarchicus, oblique tows that integrated collections Cancer sp'., and Centropages sp. copepo- over the entire water column. Some dites) reached higher abundances in the general observations can be made, however. 1 operational period than in the recent preoperational period (1988-1989). These The annual cycle of the tychoplankton results were confirmed by NOAA studies for assemblage was characterized by changes 4-32
TABLE 4-10. GEOMETRIC MEAN ABUNDANCE (No./1000m3 ) AND 95% CONFIDENCE LIMITS OF DOMINANT TYCH0 PLANKTONIC TAXA OCCURRING IN SEASONAL GROUPS FORMED BY NUMERICAL CLASSIFICATION OF MACROZ00 PLANKTON COLLECTIONS (HONTHLY MEANS) AT INTAKE STATION P2, DISCHARGE STATION P5 AND FARFIELD STATION P7, 1988-1992. SEABROOK OPERATIONAL REPORT, 1992. GROUP
- DOMINANT SPECIES b PREOPERATIONAL YEARSC OPERATIONALhEARSC n LCL i UCL n LCL i UCL 1 Harpatticoida. 7 13.3 43 133.6 4 10.9 38 128.7 Winter Poncogenia inermis 7.8 35 146.3 4.7 71 920.8 (0.65/0.61) Oedicerotidae 4.2 15 49.2 6.0 18 50.0 Neomysis americana 4.7 12 30.2 10.2 95 823.6 i
Diastylis sp. 4.6 12 30.5 1.5 20 169.1 Pseudoleptocuma minor 4.5 10 22.0 1.2 10 53.3 Hysis mixta <0.1 5 35.4 3.9 15 51.0 2 Nysis mixta 24 212.2 710 2367.8 16 245.7 647 1703.6 Late Winter-Spring Neomysis americana 22.4 56 135.5 16.0 36 77.5 y (0.61/0.56) Pontogenia inermis 16.3 30 54.5 22.9 47 97.4 U 3. Pontogenela inermis 3 0.7 9 52.4 3 <0.1 6 69.7 Spring (P7) #psis mixta <0.1 7 76.4 <0.1 21 4269.3 (0.49/0.44) Neomysis americana <0.1 7 5773.4 <0.1 6 72.0 Diasty11s sp. 2.3 5 8.5 <0.1 7 137.4 Harpactacoida <0.1 1 20.6 <0.1 5 162.6 4 Oedicerotidae 13 147.5 396 1061.8 21 75.5 221 641.6 Summer Pontogeneia inermis 105.7 178 299.4 80.1 133 220.8 (0.65/0.63' Harpactacoida 28.4 63 136.5 78.5 145 265.3 Neomysis americana 14.9 56 202.0 58.5 111 210.1 5 Pontogeneia inermis 6 20.8 161 1195.1 1 - 20 - Summer Neomysis americana 21.1 95 414.8 - 106 - (0.63/0.61) Oedicerotidae 6.0 17 44.9 - 15 - Diasty11s sp. 5.2 12 24.5 - 25 - 6 Hagactacoida 4 2.8 13 48.4 4 2.3 5 11.2
-Summer (P7) Oedicerotidae <0.1 4 36.7 <0.1 8 186.2 (0.44/O.37) Pontogeneia inermis <0.1 3 25.8 0.8 5 18.2 Calliopius laeviusculus <0.1 2 10.3 <0.1 1 3.4 Neomys2s americana <0.1 1 4.7 1.5 3 7.1 Hperiidae <0.1 1 16.1 <0.1 2 69.3 Ischyrocerus anguipes 0.0 0 0.0 <0.1 2 6.9 (continued)
_.L__m__ -_ -
TABLE 4-10. (Continued) GROUP
- DOMIEANT SPECIESb PREOPERATIONAL YEARSC OPERATIONAL YEARSC n LCL ic UCL n LCL Tc UCL 7 #eomysis americana 10 217.0 419 806.4 10 109.8 196 349.4 Fall Oedicerotidae 4.9 15 43.2 7.4 22 61.5 (0.57/0.53) 8 Neomysis americana 6 55.9 576 5839.4 10 44.7 157 543.5 Fall Poncogeneia inermis 30.5 60 116.1 19.9 68 223.9 (0.66/0.63) Diastylis sp. 16.2 57 193.7 19.5 43 92.2 Pseudoleptocues minor 9.4 30 90.7 5.8 18 50.5 Harpacticoida 7.0 16 34.9 11.7 17 25.5
- 9 Neomysis americana 4 5.8 52 403.3 5 0.5 17 228.6 L
m Fall (P7) Diascylis sp. <0.1 1 3.5 1. 3 - 3 6.8 (0.41/0.36) Oedicerotidae 0.7 1 1.5 0.2 3 10.7 Hyperiidae <0.1 1 7.6 0.2 2 4.5 10 Neomysis americana 15 320.2 825 2120.7 13 170.9 331 638.9 Fall-Early Winter Diastylis sp. 30.0 67 147.3 29.5 59 115.8 (0.65/0.63) Oedicerotidae 21.2 40 76.1 29.9 53 93.8 Pseudaleptocuma minor 12.4 28 59.6 20.8 44 93.0 b(within group similarity /between group similarity) those taxa
*preoperationt.1 contributing period =25% of total January group abundance 1988-July in either 1990; operational preo =perational or operational periods period August 1990-December 1992
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Figure 4-9. Dendrogram and seasonal gmups formed by numerical classif'ication of monthly mean log (x+1) transformed abundances (no/1000 m3 of tychoplanktonic species of macrozooplankton at intake Station P2, discharge Station P5 and farfield Station P7,1988 1992. Seabrook Operational Report,1992. 4-35 i l
ZOOPLANKTON in relative abundance of the three omni- together (82% of collections, Figure 4-9), present taxa as well as three intermittent The assemblage at Station P7 was distinct dominants (Harpacticoida, Olastylls sp. , from that at the nearfield stations in 58% and #rsis mixta). Abundances were lowest of the collections. Although Station P7 in mid-winter (primarily February; Group generally exhibited similar seasonal
- 1) although the six dominants were all patterns to Stations P2 and P5, abundances present. In the spring (Group 2), the of dominant ta.xa were lower, resulting in assemblage was overwhelmingly dominated the formation of three groups (3,6, and by #ysis mixta, whose abundance has 9) composed solely of farfield collec-historically been an order of magnitude tions. Results of numerical classifica-higher than that of other species. N. tion were substantiated by MANOVA, which mixta juveniles tend to migrate offshore indicated that there were significant during the spring in New Hampshire waters differences among stations in species (Grabe and Hatch 1982). Spring collec- composition (p=0.0001). These spatial tions at Station P7 have occasionally been differences are likely the result of depauperate throughout the study, as dif ferences in substrate and proximity to represented by Group 3. Summer colloc- Hampton Harbor.
tions (Groups 4,5 and 6) were character-ized by varying abundances of codominant Seasonal groups of the tychoplankton amphipods Poncogenela inermis and Oedi- assemblage were similar between Stations cerotidae and the mysid Neomysis america- P2 and PS during preoperational and nn. Peak abundances of Neomysis americana operational periods throughout most of the - typified fall and early winter (Groups year (Figure 4-9). The assemblage 7,8,9 and 10) collections. Collections exhibited greater variability (as indicat-from 1992 followed the same basic pattern ed by collections being associated with observed in recent preoperational years more groups) preoperationally during (ligure 4-9; Table 4-1C), with one February, June and August (Figure 4-9). exception. September collections were There was little consistency at Station more closely allied to summer collections P7, partially an artif act of the relative-than fall collections while in most ly low abundances at this station. HANOVA previous years September was classified results indicated that differences between as a " fall" community. The main differ- preoperational (1988-1989) and operational l once between these two groups was the (1991-1992) periods existed (p=0.0001), presence of Oedicerotidae in summer and with abundances higher during operational absence of Olascy11s sp. This situation years than in recent preoperational years. also occurred in 1988 and 1991, and only This shif t occurred in both nearfield and at Station P2. forfield stations (Figure 4-9; Station X Preop-Op, p=0.83), indicating a broadscale Differences between the nearfield and trend. ) farfield areas in tychoplankton assem- I blages from 1988 through 1992 were ap-parent from numerical classification. Stations P2 and P5 were usually grouped 4-36 i
- a. . . .
200 PLANKTON 4.3.3.2 Selected Soecies Copepodito abundances averaged over the operational period at all stations were gelanus finmarchicus not significantly dif ferent from mean i abundances for both the long-term preoper- l Calanus finnarchicus, particularly the ational period (Table 4-11) and the recent copepodite lifestage, has historically preoperational period (Table 4-12). In l been a dominant macrozooplankton species, recent years (1987-1989 and 1991-1992), as observed in the community assessment average abundances at Stations P2 and P5 (Table 4-9) . Both copepodites and adults have been similar, and significantly are usually present throughout the year. greater than those at Stat. ion P7 (Table Average monthly copepodito abundances at 4-12). These differences have been Station P2 have historically exhibited a consistent regardless of operational broad spring-to-f all peak (Figure 4-10). status, as indicated by the nonsignificant Operational and 1992 abundances followed interaction term (Table 4-12). Signifi-a similar pattern, with slightly more cant differences were also noted among exaggerated seasonal extremes. Operation- years and months. Mean adult abundances al or 1992 monthly mean abundances at Stations P2 and P7 have declined exceeded the upper 95% confidence limit between the preoperational period (all of preoperational means in May, June, years) and the operational period, while November, and Decembar, end were less than abundances at Station P5 have remained the lower 95% confidence limit of preoper- stable (Table 4-11). However, average ational means during January, February, adult abundances have been similar among and March (Figure 4-10). the three stations and have not changed significantly betwoon the recent preopera-Adult monthly mean abundances at Station tional period and the operational period P2 have historically shown a somewhat (Table 4-12). Abundances differed weaker seasonal pattern than copepodite significantly among years and months. abundances, although adult abundances have also tended to peak between late spring In the community assessment (Sec. and early f all (Figure 4-10). Adult abun- 4.3.3.1), the MANOVA indicated that C. dances generally followed a similar finmarchicus showed significantly higher seasonal pattern during the operational abundances during the operational period period as a whole, but departed from the compared to the recent preoperational norm during the late spring in 1992. As period (1988-1989). The ANOVA, however, copepodites reached peak abundances in May indicates no preoperational-operational and June in 1992, adult abundances differences. Two factors contribute to declined to zero. This occurred at all these dif fering conclusions. The MANOVAs three stations (NAI, unpublished data), combined copepodites and adults, while Adult abundances recovered strongly during copepodites and adults were analyzed July, August, and September, to levels separately in the ANOVA. The more about equal to the upper 95% confidence important factor, however, is that 1987 limit of preoperational means, collections were included in the ANOVA, but not in the MANOVA. In 1987, copepo-4-37
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{ 1 i i i i i i i i i i i JAN TEB MAR APR MAY EN Rt AUo SEP OCT M)V DEC i 1 MONTil i l Figure 410. Log (x+1) abundance (no/1000 m3) of Calanusfinmarchtcus copepodites and adults and Carcinus maenar larvac; monthly means and 95% conndence intervals over all preopemtional years (1978 1984,19861989) and monthly means for the operational period (1991 1992) and 1992 at intake Station P2. Seabrook Opemtional Report 1992. 1 4-38 l l 1
TABLE 4-11. GEOMETRIC MEAN ABUNDANCE (No./1000 c?) AND UPPER AND LOWER 95% CONFIDENCE LIMITS OF SELECTED MACROZ00 PLANKTON SPECIES AT STATIONS P2, PS, AND P7 DURING PREOPERATIONAL YEARS AND GEOMETRIC MEAN ABUNDANCES IN THE OPERATIONAL YEARS (1991-1992) AND 1992. SEABROOK OPERATIONAL REPORT, 1992. PREOPERATIONAL SPECIES /LIFESTAGE OPERATIONAL 1992 (peak period) STATION LCL i' UCL i" i Calanus finmarchicus P2 3,942 5,668 8,150 5,634 5,205 copepodites PS 4,670 7,697 12,686 7,317 8,128 (January-December) P7 2,096 3,701 6,534 3,572 3,870 Calanus finnarchicus P2 52 103 204 41 42 adults PS 25 61 148 68 74 (January-December) P1 20 65 203 28 39 Carcinus maenas P2 2,854 4,312 6,514 10,092 9,740 i larvae P5 1,823 4,549 11,352 11,080 10,596
$ (June-October) P7 2,613 4,633 8,214 6,632 4,293 Crangon septenspinosa P2 181 244 329 339 405 zoese and postlarvae PS 142 201 284 299 362 (January-December) P7 114 190 316 140 125 Neomysis americana P2 98 193 381 205 263 all lifestages PS 20 58 164 54 84 (January-December) P7 28 68 162 28 44
" Years sampled:
Preoperational: P2 = 1978-1984, 1987-1989 P5 = 1987-1989 P7 = 1982-1984, 1987-1989 Mean of annual means Nean of annual means, 1991 and 1992
. _ _ . . _ _ _ _ _ _ _ . _ _ - _ _ _ m __m___m ._ _ . a-.. m F Nh -
Y
TABLE 4-12. RESULTS OF ANALYSIS OF VARIANCE COMPARING ABUNDANCES OF SELECTED MACR 0 ZOOPLANKTON SPECIES FROM STATIONS P2, PS, AND P7 DURING PREOPERATIONAL (1987-1989) AND OPERATIONAL (1991-1992) PERIODS. SEABROOK OPERATIONA' ~ PORT, 1992. SPECIES" SOURCEb d.f. SS F tt0LTIPLE COMPARISONSh Calanus finmarchicus coyepodites Preop-Op' 1 1.14 2.92 NS (J anuary-December) Year (Preop-pp)d Month 3 4.11 3.50* (year) 55 488.66 22.68*** - Station 2 3.30 4.22* PS P2 P7 Preop-Op X Station9 2 0.33 0.42 NS Error 296 115.96 Calanus finmarchicus Preop-Op 1 0.08 0.08 NS adults Year 3 16.67 5.25** (January-December) Month (Preop-Op) (Year) 55 439.37 7.54*** Station 2 4.92 2.32 NS Preop X Station 2 0.48 0.23 NS Error 296 313.40 Carcinus maenas 1 0.97 2.02 NS larvae Preop-(OpPreop-O Year 3 0.27 0.19 NS (June-September) Month (Year) p) 15 24.21 ' 3.36*** Station 2 1.19 1.24 NS Preop X Station 2 0.15 0.15 NS T Error 96 46.12 $ Crangon'$eptems$arvae inosa Preop Op 1 0.11 0.40 NS zoeae an post Year (Preop-Op) Month 3 2.50 2.99* (January-December) (Year) 55 422.18 27.62*** Station 2 7.34 13.20*** P2 P5>P7 Preop X Station 2 0.28 0.51 NS Error 296 82.26 Neomysis americana 1 1.74 3.16 NS all lifestages Preop (-OpPreop-O Year 3 32.88 19.88*** (January-December) Month (Year) p) 55 127.89 4.22*** Station 2 41.40 37.55*** P2>PS>P7
~ Preop X Station 2 0.05 0.05 NS Error 296 163.19
- Based on twice monthly sampling periods Commercial operation began in August 1990; 1990 data left out of analysis to keep a balanced design in the MOVA procedure.
*Preoperational (1987-1989) versus operational (1991-1992) periods, regardless of station; 1987-1989 d
reflects the period of time-that all three stations were s q led coincidentally. Year nested within preoperational and operational periods, regardless of station.
- Month nested within year, regardless of station.
Station P2 vs. station PS vs. station P7, regardless of year. 8 Interaction between main effects. NS. = Not significant (p >0.05)
* = Significant (0.05 2 p >0.01)
** = Highly sipificant (0.01 2 p'>0.001) ,
*** = Very highly significant'(0.001 2 p) h Ranked in decreasing order. Underlines indicate no significant dif ference in least-squares means (a 5 .05).
ZOOPLANKTON dite abundances (which in general out- peaked over a broad period between late weigh adult abundances) were higher than spring and early fall (Figure 4-11). in 1988 and 1989, and similar to abundanc- Operational monthly means were higher than es observed in 1991 (NAI 1991 and 1992). the upper 95% confidence limit of preoper-Excluding 1987 from the MANOVA served to ational means in March, April, May, and emphasize the 1988-1989 trough in the July. In October, however, the operation-long-term cyclical pattern of abundances, al mean abundance was lower than the lower thus leading to the observed pre- 95% confidence lim!.t nf the preoperational operational-operational differences. mean (Figure 4-11). Abundances have increased slightly Carcinus moenas between the preoperational (all years) and operational periods at Stations P2 and PS, Larvae of the green crab Carcinus moenas and have decreased slightly at Station P7 have historically shown a strong bimodal (Table 4-11). At all three stations, seasonal pattern at Station P2, with peak however, abundances have shown no signifi-abundances occurring during the late cant difference over the period of 1987 spring through early f all (Figure 4-10), to 1992 (Table 4-12). Regardless of The timing and abundance of green crab operational status, abundances have been larvae were very similar during both the similar between Stations P2 and PS, yet preoperational and operational periods, significantly greater than abundances at alttough operational monthly mean abun- Station P7 (Table 4-12). Abundances dances exceeded the upper 95% confidence showed significant differences among limit of preoperational means in May, months. June, and July. Over all preoperational years and opera- Econvsis americana tional years, average peak period abun-dances have been similar at both nearfield For the combined lifestages of Neomysis , and f arfield stations (Tables 4-11, 4-12), americana (ovigerous and larvigerous and have increased between preoperational females, adults, immature adults, and and operational periods (Table 4-11). Juveniles), monthly mean abundances at Average abundances have not, however, Station P2 during both the preoperational increased significantly between the recent and operational periods showed no consis-preoperational period and the operational tent seasonal pattern (Figure 4-11). period (Table 4-12). Significant dif fer- Abundances averaged over all months at ences were noted among months. Stations P2, PS and 77 have also remained stable between the preoperational and operational periods, and there have been : Crancon septemspinosa no significant preoperational-operational ! differences observed at all three stations Abundances of the zoeae and post-larvae combined -(Table 4-12). During both the of Crangon septomspinoss have histarically recent preoperational period and the f 4-41
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JAN FEB MAR APR MAY . RJN EL AtJO SEP. OCr NOV DEC MONTH d Ovigerous & Larviserous O Aaua 4 t= = rure ^aus Juvenite Figure 4-11. Log (x+1) abundance (no./1000 m% . ;ngon septemspinosa (zoca and post larvac) and Neomysis americana (all lifesta, ,, monthly means and 95% confidence intervals over all preoperat5nal years (1978-1984,' 19861989) and monthly means for the operational pcdod (1991 1992) and 1992; and mean percent composition of Neomysis , americana lifestages over all preoperational years (1978-1984,1986-1989) and for the operational period (1991-1992) at intake Station P2. Seabrook Operational Report,1992. 4-42 P 9 y f .c - - * -
ZOOPLANKTON operational period, abundances of all life time immature adults accounted for an stages combined have been significantly increasing proportion of the total. higher at Station P2 than at either Station P5 or P7 (Table 4-12). 4.4 DISCUSSION Although the abundance of the combined lifestages changed relatively little 4.4.1 COMMUNITY throughout the year, the individual lifestages showed strong seasonal patterns Entrainment of occurrence (Figure 4-11). During both the preoperational and operational The focus of monitoring plankton in the periods, immature adults were the most intake area was to evaluate the ef fect of common lifestage during January and entrainment of organisms by the circulat-February. The decline in the relative ing water system (CWS) on community abundance of immature adults during the structure and population levels in the . early spring was paralleled by an increase nearfield area. Due to the limited in the relative abundance of adults. By control of their horizontal movements and May, juveniles were also abundant. During often broad vertical distribution in the May, adults accounted for relatively more water column, most types of planktonic. , of total Neomysis abundance, and juveniles organisms could be exposed to entrainment. and immature adults accounted for rela- Estimates of total monthly levels of tively less during the operational period entrainment were presented (Table 4-8) to compared to the preoperational period. quantify losses to bivalve larvae. During the operational period, a larger Community structure and abundances of percentage of ovigorous and larvigerous selected species in the nearfield area females were present in May than during during commercial operation were compared the preoperational period. Differences to historical conditions and to farfield between the two periods were also seen in conditions. These comparisons address the June. Fewer juveniles and adults and more question of whether the balanced, indige-Immature adults were present during the nous planktonic populations within the operational period compared to the study area have been affected by the plant preoperational period. intake during the commercial operation to date. During the remainder of the year, percent composition of the lifestages was Although Seabrook Station has operated similar between the two periods. Adults its circulating water system at varying and immatures were the most common levels since 1985, no power or heated lifestages during July and August. discharge were produced until the summer Juveniles increased between September and of 1990. Entrainment of bivalve larvae October, when they were the dominant has been monitored since June 1990. These lifestage. Juveniles began to decline collections provide a measure of the
-during November and December, at which actual number of organisms directly affected by plant entrainment.
4-43
ZOOPLANKTON The number of bivalve larvae entrained Bivalve Larvae monthly was estimated from June through October 1990, late April through early Varying abundances of Flate11a sp., August 1991, and late April through June Nytilus edulis and Feteronomia squamula 1992; sampling was not conducted during defined most seasonal groups identified scheduled maintenance outages of the plant by the community analysis. The species in 1991 and 1992. Three taxa, Nyc11us composition during the operational period edu11s (blue mussel), Feteranomia squamula was similar to previous years. However, and Flatella sp. , accounted for more than community structure in 1991 and 1992 85% of the bivalve larvae entrained during differed significantly from recent June and July of each year (Figure 4-7), preoperational years (1988-1989) because
#odlolus modfolus was intermittently of significantly lower abundances of entrained during 1990 and 1991. Monthly almost all taxa in 1992 (Table 4-13).
entrainment of all taxa was less in 1991 Community structure, however, was similar and 1992 in comparison to 1990. Reduced at nearfield and farfield stations both l CWS flows during outage periods in summer preoperationally and during the operation-when larvae typically reach their peak al period. Therefore, entrainment of abundance levels in local coastal waters bivalve larvae in the CWS of Seabrook led to reduced entrainment. Furthermore, Station is not suspected to have caused reduced abundances of N. edulis larvae depressed abundances of bivalve larvae. observed in local coastal waters (P2, P5, Although umboned larvae densities. were P7) in 1991 and 1992 compared to 1990 depressed, examination of the samples contributed to lower entrainment levels. Indicated that straight-hinged larvae, I which are not enumerated, were abundant. i l It is possible that lower-than-average Microzooolankton temperatures may have delayed or prevented metamorphosis to the umboned stage. The Seasonal patterns of the natural appearance of Elate 11a sp. , Anomia sp. , assemblage of microzooplankton have and Mytilidae recruiting to bottom panels historically been dominated by the in 1992 was normal in terms of the timing population dynamics of the copepods and intensity (Section 6.0). Patterns of Olthona sp. and Pseudocolanus sp. and the Mytilidae settlement on surface panels production of early lifestages (nauplius occurred at the same time and in similar larvae) of other copepods that have been levels to previous years (Section 7.0). present year-round. Seasonally, other There were no indications that benthic taxa such as polychaete larvae, bivalve recruitment of Mytilidae or Nodfolus l larvae and tintinnids influenced community mod /olus was depressed in 1992 as a result j structure. Since Seabrook began commer- of low densities of larvae. l cial operation, species composition continued to resemble the historical patterns (Table 4-13). I l 1 4-44 j i
ZOOPLANKTON TAB LE 4 - 13.
SUMMARY
OF POTENTIAL EFFECTS (BASED ON CLASSIFICATION AND MANOVA RESULTS) 0F OPERATION OF SEABROOK STATION INTAKE ON THE INDIGEN0US ZOOPLANKTON COMMUNITIES. SEABROOK OPERATIONAL REPORT, 1992.
. DIFFERENCES BETWEEN OPERATIONAL AND OPERATIONAL PERIOD PREOPERATIONAL PERIODS COMMUNITY SIMILAR TO CONSISTENT ATTRIBUTE PREOPERATIONAL PERIOD 7 AMONG STATIONS 7 MICROZ00 PLANKTON Community Structure yes" yes 1
h Abundances no-variable among taxa yes i BIVALVE LARVAE Community Structure yes" yes Abundances Op< Preopb ,e yes j MACROZ00 PLANKTON Holo /meroplankton j Seasonal occurrence yes, except no " winter" yes i group of reduced abun-dance in 1992* i Abundances Op> Preop (most dominant yes 1 I taxa)* Tychoplankton Seasonal occurrence yes yes Abundances Op> Preop
- yes u
"Dased on results of numerical classification b
Based on comparisons of group mean abundances Based on MANOVA results 4-45
ZOOPLANKTON 1 Holo- and Mercolanktonic (Meise-Munns et al.1990). These factors Macrozooolankton could have contributed to the difference of the holo- and meroplanktonic macro-The annual cycle of the holo- and zooplankton assemblage observed in January .l meroplanktonic components of the macro- 1992. , zooplankton community in coastal waters of New Hampshire is similar to other Temperatures resembled preoperational portions of the Gulf of Maine (Anderson conditions during 1992 and were therefore 1990; Tremblay and Roff 1983; Sameoto unlikely to have contributed to the _1 I and Herman 1992), and has remained somewhat atypical December macrozoo-consistent over the past five years. plankton community, which resembled a Minor exceptions include the late winter- typical fall community. It is possible early spring period (February through that the warm winter of 1991-1992 enhanced April), which has exhibited greater the survival of the warm-water species' ' variation among years (reflected in more Cencropages typicus and C. hamatus (Grant seasonal groups) than other periods. Both 1988) sufficiently to enable them to surface and bottom salinity have exhibited endure until their fall breeding period, higher variability among years between In most seasonal groups, abundances of C. February and April than during other typicus tended to be higher in the months (see Section 2.0), indicative of operational collections than in preopera-varying meteorological influerces (i.e. tional collections; MANOVA results precipitation) affecting salinity directly indicated that differences in abundance ., and through runoff. Storms often cause were significant. g shelf water masses to mix with coastal water masses. Despite relatively low Many holo- and meroplankton species have salinities in February (and March in near- reached higher abundances during opera-bottom waters), the 1992 macrozooplankton tional years than during recent (1988-community resembled previously-observed 1989) preoperational years (Table 4-13). communities. This may be associated with a similar , trend in the phytoplankton community. The macrozooplanktonic assemblage in Copepods such as Acartia spp. , Calanus 1992 did differ from expected patterns of finmarchicus and Temora longicornis are reduced abundances in January and Decem- sensitive to phytoplankton abundance and ber. In January, species composition can produce substantially more eggs when resembled the community normally occurring phytoplankton are abundant (Peterson 1985, in February and later. Elevated tempera- Runge 1988), although this trend has not tures in the fall of 1991 (NAI 1992) may been noted in this study. Reproduction have af fected the observed increase in of other copepods that showed areawide plankton abundances, enhanced the survival changes in this study. (01chona sp., of overwintering copepods, and may have Pseudocolanus sp.), however, is not as stimulated earlier spawning of barnacles, closely linked to primary production l Overwintering stages may control the (Runge 1988), abundances of various copepod species 4-46
ZOOPLANKTON Although holo- and meroplanktonic that occasionally occurred during the community s t ructiure was qualitatively preoperational period as well. similar among Stations P2, PS, and P7, quantitative examination of abundances Comparison of the entire tychoplankton indicated that spatial differences assemblage across stations revealed that, occurred, and in fact, persisted from with the exception of hyper 11d amphipods, preoperational through operational periods all taxa were more abundant in the (as evidenced by the MANOVA's significant nearfield than in the farfield. Usually, station term and insignificant interaction abundances were similar at Stations P2 and term). Specific differences were not PS. Substrate preferences are exhibited clearcut. Fewer than 20% of the 50 taxa by tychoplanktonic species such as mysids examined exhibited significant station (Vig1cy and Burns 1971, Pezzack and Cory difforences. Differences may be related 1979, Mauer and Wigley 1982), amphipods to water quality characteristics (Section (Bousfield 1973) and cumaceans (Watling 2.0). Temperature and dissolved oxygen 1979). Substrate type and complexity, as have been higher in the nearfield (P2 and well as proximity to Hampton-Seabrook PS) while bottom salinity and nitrogen- estuary, may account for some of the nutrients have been higher in the f arf fold observed differences. Historically, (P7)(Section 2.0). The proximity af Neomysis americana, Pontogenela inermis, Stations P2 and P5 to Hampton Harbor may Diasty11s sp. and oedicarotid amphipods partially account for water quality have had higher abundances at Station P2, patterns, where substrate is sand and cobble, than at P7, where the substrate is mainly sand (NAI 1985, 1988, 1989 and 1990). In Tychoolanktonic Macrozooolankton addition, Hampton-Seabrook estuary may provide a source of N. americana to The tychoplanktonic community, composed Stations P2 and P5. At Station PS, where of species that inhabit both the substrate the substrate is largely ledge outcrop and and the water column, exhibited greater cobble, densities of Blastylls sp. have variability both temporally and spatially been lower than at P2 (NAI 1988, 1989). than the holo- and meroplanktonic communi-ty. Excursions into the plankton can be While both temporal and spatial differ-related to such factors as light, lunar ences have been observed in various I cycle, storm events, reproduction and components of the macrozooplankton nonspecific aggregation. These factors community, these differences have been can influence apparent abundance dramati- consistent. Although abundances of a ., cally (Mauchline 1980). number of species have differed between the preoperational ar.d operational Seasonal changes in species composition periods, similar changes have occurred at were similar between preoperational and nearfield and farfield locations. Other operational years, except during Septem- species, particularly tychoplankton, have l bor. The summer assemblage extended into exhibited spatial patterns that have been ! September in 1991 and 1992, a situation consistent from preoperational to opera-I 4-47
ZOOPLANKTON tional periods. The long-term consistency operational years (1991-1992) for selected in distribution indicates that operation microzooplankton species were generally of Seabrook Station's cooling water system similar to patterns observed during the has not affected the macrozooplankton preoperational period at nearfield Station community. P2 (Table 4-14). Although ANOVAs detected significantly lower preoperational mean densities for Eurytemora sp. copepodites, 4.4.2 SELECTED SPECIES Eurytemora sp. adults and Pseudocalanus/ Calanus sp. nauplii, and significantly MicrozooolanktoD higher abundances of Olthona sp. copepo-dites and adults during station operation, Trends in both the densities and pattern the general lack of significance in the of seasonal variation recorded during spatial (Area) and operational status TAB LE 4 - 14.
SUMMARY
OF POTENTIAL EFFECTS (BASED ON ANOVA RESULTS) 0F OPERATION OF SEABROOK STATION INTAKE ON ABUNDANCES OF SELECTED INDIGENOUS ZOOPLANKTON SPECIES. SEABROOK OPERATIONAL REPORT, 1992. PLANKTON OPERATIONAL PERIOD DIFFERENCES BETWEEN SELECTED SPECIES SIMILAR TO OPERATIONAL AND LIFESTAGES PREOPERATIONAL" PERIOD 7 AND PREOPERATIONAL PERIODS CONSISTENT AMON0 STATIONS? MICR0 ZOOPLANKTON Eurytenora sp, copepodites Op< Preop yes E. herdman 1 adults Op< Preop yes Pseudocalanus/Calanus nauplii Op< Preop yes Pseudocalanus sp, copepodites yes yes adults yes yes Olthona sp. nauplii yes yes copepodites Op> Preop yes adults Op> Preop yes BIVALVE LARVAE Hytilus edulls larvae Op< Preop yes MACROZ00 PLANKTON Calanus finmarchicus copepodites yes yes adults yes yes Crangon septemspinosa larvae yes yes Carcinus maenas larvae yes yes Neomysis americana yes yes "recent preoperational years, 1987-1989 4-48
.- .. . - . . - - -- - - -~
l 1 l ZOOPLANKTON l l 1 interaction (Preop-Op X Area) terms preoperational period (Table 4-14). One ) indicated that the temporal differences species, Neomysis americana, showed l Were observed throughout the study area significant nearfield-farfield dif ferences
- (i.e., at both nearfield and farfield during both the preoperational and stations) and therefore could not be operational periods. Abundances have attributed to a plant effect, remained stable over time, and the relationship of abundances between the three stations has also remained un-Elvalve Larvae changed.
Umboned larvae of #ytilus edulis have been generally present in the water column 4.5 LITERATURE CITED from mid-May through the end of the sampling program. Their protracted Anderson, J.T. 1990. Seasonal develop-presence was probably due to spawning ment of invertebrate zooplankton on patterns and the duration of larvae life. Flemish Cap. Mar. Ecol. Progr. Ser.
- In Long Island Sound, spawning occurred 67:127-1409.
over a two-to-three month period and was asynchronous among local populations (Fell Bayne, B . L. 1965. Growth and the delay and Balsamo 1985). Three-to-five weeks of metamorphosis of the larvae of is required for larvas development (Bayne Nytilus edu11s (L.) Ophelia 2:1-47. 1976), and metamorphosis can be delayed up to 40 days until suitable settling 1976. The biology of mussel conditions are encountered (Bayne 1965). larvae. Chap. 4 .in Bayne , D.L., ed. Although the seasonal pattern of #. edulis Marine Mussels: Their Ecology and larvae in 1991 and 1992 was similar to Physiology. IBP 10. Cambridge Univ. previous years, operational period Press. pp. 81-120. abundances were significantly lower due to low abundances in 1992. However, this Boesch, D.F. 1977. Application of pattern was observed at each of three numerical cleasification in ecological I stations, suggesting that this phenomena investigations of water pollution. U.S. is unrelated to the operation of Seabrook Environmental Protection Agency, Station. Ecological Research Report Agency, l Ecological Research Report, 114 pp. Hacrozooolankton Bousfield, E. L. 1973. Shallow-water Gammaridean Amphipoda of New England. .
- There has essentially been no change in Comstock Publishing Assoc. (Cornell the abundances or seasonality of any of University Press; Ithaca, NY and London.
the macrozooplankton selected species. 312 pp. Average abundances of all selected species during the operational period were not significantly different from the recent , I 4-49
ZOOPLANKTON Clifford H.T. , and W. Stephenson. 1975. Katona, S.K. 1971. The developmental An introduction'to numerical classifica- stages of Eurytemora affinis (Poppe, tion. Academic Press, New York. 229 1880) (Copepoda, Calanoida) raised in pp. laboratory cultures, including a com-parison with the larvae of Eurytemora Davis, C.S. 1984. Interaction of a americana Williams,1906, and Eurycemora copepod population with the mean herdman 1 Thompson and Scott, 1897. circulation of Georges Bank. J. Mar. Crustaceana 21:5-20. Res. 42:573-590. Marcus, N.H.1984. Recruitment of copepod Fell, P.E. and A.M. Balsamo. 1985, nauplii into the plankton:- importance Recruitment of Nyt11us edu11s L. in the of diapanse eggs and benthic processes. Thames Estuary, with evidence for Mar. Ecol. Prog. Ser. 15:47-54, differences in the time of maximal settling along the Connecticut shore. Mauchline, J. 1980. The Biology of Estuaries 8:68-75. Mysids: Part I, in The Biology of Mysids and duphausiids. Adv. Mar. Biol. Grabe, S.A. and E.R. Hatch. 1982. 18:3-372. Aspects of the biology of Nysis mixta (Lilljeborg 1852)(Crustacea, Mysidacea) Maurer, D. and R. L. Wigley. 1982, in New Hampshire coastal waters. Can. Distribution and ecology of mysids in J. Zool. 60(6):1275-1281. Cape Cod Bay, MA. Biol. Bull. 163:477-491. Grant, G.C. 1988. Seasonal occurrence and dominance of Centropages congeners Meise-Munns, C. , J. Green, M. Ingham and in the Middle Atlantic Bight, USA. D. Mountain. 1990. Interannnual Hydrobiol. 167/168:227-237. variability in the copopod populations of Georges Bank and the Western Gulf of Grice, G.D. and N.H. Marcus. 1981. Maine. Mar. Ecol. Progr. Ser. 65:225-Dormant eggs of marine copepods. 232. Oceanogr. Mar. Biol. Ann. Rev. 19:125-140. Normandeau Associates Inc. 1978. Seabrook Environmenta! 3tudies, 1976-Harris, R.J. 1985. A primer of multi- 1977. Monitoring of plankton and variate statistics. Orlando: Academic related physical-chemical factors. Press. 575 p. Technical Report VIII-3. l Jossi, J.W. 1991. Gulf-of-Maine copepods . 1979. Seabrook Environmental hit 11-year high. In Northeast Fisher- Studies, July through December 1977. ies Center End-of-Year Report for 1990. Plankton. Technical Report IX-1. NOAA-NMFS.
. 1980. Annual summary report for 1978 hydrographic studies off 4-50
Z00PLANXTON Hampton Beach, New Hampshire. Preopera- environmental conditions in the Hampton-tional ecological monitoring studies for Seabrook area during the operation of i Seabrook Station. Technical Report X-2. Seabrook Station. Tech. Rep. XXIII-I. l
. 1984. Seabrook Environmental .1993. Seabrook Environmental Studies. 1983 data report. Technical Studies. 1992 Data. Unpublished Data Report XV-1. Tables.
. 1985. Seabrook Environmental Peterson, W.T. 1985. Abundance, age Studies, 1984 A characterization of structure and in situ egg production baseline conditions in the Hampton- rates of the copepod Tecoro longicornis Seabrook Area, 1975-1984. Technical in Long Island Sound, New York. Bull.
Report XVI-II. Mar. Sci. 37(2):726-738.
. 1988. Seabrook Environmental Pezzack, D.S. and S. Corey. 1979. The Studies. 1987. A characterization of life history and distribution of baseline conditions in the Hampton- Neomysis scaricana (Smith) (Crustacea, Seabrook area. 1975-1987. A preopera- Mysidacea) in Passamaquoddy Bay. Can, tional study for Seabrook Station. J. Zool. 57:785-793.
Technical Report XIX-II. Runge, J.A. 1988. Should we expect a
. 1989. Seabrook Environmental relationship between primary production Studies. 1988. A characterization of and fisheries 7 The role of copepod baseline conditions in the Hampton- dynamics as a filter of trophic vari-Seabrook area. 1975-1988. A preopera- ability. Hydrobiol. 167/168:61-71.
tional study for Seabrook Station. Technical Report XX-II. Sameoto, D.D. and A.W. Herman. 1992. Ef fect of the outflow from the Gulf of 1990. Seabrook Environmental St. Lawrence on Nova Scotia shelf Studies. 1989. A characterization of zooplankton. Can. J. Fish. Aquat Sci. baseline conditions in the Hampton- 49:857-869. Seabrook area. 1975-1989. A preopera-tional study for Seabrook Station. SAS Institute, Inc. 1985. SAS User's Technical Report XXI-II. Guide: Statistics, version 5 edition. SAS Institute, Inc. , Cary, N.C. 956 pp.
. 1991. Seabrook Environmental Studies, 1990. A characterization of Sherman, K. 1966. Seasonal and areal environmental conditions in the Hampton- distribution of Gulf of Maine Coastal-Seabrook area during the operation of Zooplankton,1963. ICNAF Special Publ.
Seabrook Station. Tech. Rep. XXII-II. No. 6. pp. 611-623.
. 1992. Seabrook Environmental . 1991. Northwest / northeast Studies, 1991. A characterization of Atlantic zooplankton show different 4-51
ZOOPLANKTON l l trends. In Northeast Fisheries Center End-of-Year Report for 1990. NOAA-NMFS. Sherman, K., M. Grosslein, D. Mountain, D. Busch, J. O'Reilly and R. Theroux. lj 1988. The continental shelf ecosystem
]
off the northeast coast of the United J States. Chapter 9, pp. 279-337. In H. J Postma and J.J. Zijlstra, Ecosystems of the World 27. Continental Shelves. Elsevier, Amsterdam. Sneath, P.H.A., and R.R. Sokal. 1973. Numerical taxonomy. The principles and ' practice of numerical classification. W.H. Freeman Co., San Francisco. 573 l pP-Tremblay, M.J. and J . C . Roff. 1983. k l Community gradients in the Scotian shelf l zooplankton. Can. J. Fish. Aquatic. Sci. 40:598-611.36 I Watling, L. 1979. Marine flora and f auna j i of the Northeastern United States, Crustacea: Cumacea. NOAA Technical l Report NMFS Circular 423. 23 p. Wigley, R.L. and B.R. Burns. 1971. Distribution and biology of mysids (Crustacea, Mysidacea) from the Atlantic , Coast of the United States in the NMFS l Woods Hole collection. Fish. Bull. 69(4):717-746. i
)
l l l l l 4-52 . l
I l l
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TABLE OF CONTENTS l PAGE l l 5.0 FISH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 5.1 OBJECTIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 5.2 MET 110DS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 5.2.1 Ichthyoplankton . . . . . . . . . . . . . . . . . . . . . 5-1 5.2.1.1 Of fshore Sampling . . . . . . . . . . . . . . . . 5-1 5.2.1.2 Entrainment Sampling . . . . . . . . . . . . . . . . 5-2 5.2.1.3 Laboratory Methods . . . . . . . . . . . . . . . . 5-3
- 5. 2.1. 4 Analytical Methods . . . . . . . . . . . . . . . 5-3 5.2.2 Adult Fish . . . . . . . . . . . . . . . . . . . . . . . . 5-5 5.2.2.1 Pelagic Fish Community . . . . . . . . . . . . . 5-5 5.2.2.2 Demersal Fish Community . . . . . . . . . . . . 5-5 5.2.2.3 Estuarine Fish Community . . . . . . . . . . . . 5-5 5.2.2.4 Impingement . . . . . . . . . . . . . . . . . . 5-5 5.2.2.5 Analytical Methods . . . . . . . . . . . . . . . . 5-7 5.3 RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . 5-9 5.3.1 Ichthyoplankton . . . . . . . . . . . . . . . . . . . . . . 5-9 5.3.1.1 Community . . . . . . . . . . . . . . . . . . . . 5-9 i 5.3.1.2 Selected Species . . . . . . . . . . . . . . . . 5-17 5.3.1.3 Ichthyoplankton Entrainment . . . . . . . . . . . . 5-25 5.3.2 Adult Fish . . . . . . . . . . . . . . . . . . . . . . . . 5-26 5.3.2.1 Communities . , . . . . . . . . . . . . . . . 5-26 5.3.2.2 Selected Species . . . . . . . . . . . . . . . . . 5-35 5.3.2.3 Impingement . . . . . . . . . . . . . . . . . . 5-52 l
-1 l
5.4 DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-54 j 5.4.1 Ichthyoplankton . . . . . . . . . . . . . . . . . . . . . . 5-54 -l 5.4.1.1 Community . . . . . . . . . . . . . . . . . . . . . 5-54
- 5. 4.1. 2 Selected Species . . . . . . . . . . . . . . . . . 5-54 5.4.1.3 Entrainment . . . . . . . . . . . . . . . . . . . . 5-57 l
,i 5-1
PAGE , 1 5.4.2 Adult Fish . . . . . . . . . . . .. . . . , . . . . . . . . 5-58 5.4.2.1 General . . . . . . . . . . . . . . .. . . . . . . 5-58 5.4.2.2 Pelagic Fish . . . . . . . . . . .. . . . . . . . 5-59 . 1 5.4.2.3 Demersal Fish . . . . . . . . . . . . . . . . . . . 5-60 5.4.2.4 Estuarine Fish . . . . . . . . . . . . . . . . . 5-62 5.4.2.5 Impingement . . . . . . . . . . . . . . . . , . . 5-63 5.4.2.6 Effects of Station Operation . . . . . . . . . . 5-66 5.5 LITERATURE CITED , . . . . . . . . . . .. . . . . . . . . . . 5-67 1 1 5-LL
1 C LIST OF FIGURES PAGE 5-1. Ichthyoplankton and adult fish sampling stations . . . . . . . . 5-2 5-2. Dendrogram and temporal / spatial occurrence pattern of fish egg assemblages formed by numerical classification of ichthyo-plankton samples (monthly means of log (x+1) transformed number ' per 1000 m3 ) at Seabrook intake (P2), discharge (PS), and farfield (P7) stations, July 1986-December 1992 . . . . . . . . . 5-10 5-3. Dendrogram and temporal / spatial occurrence pattern of fish - larvae assemblages formed by numerical classification of ichthyoplankton samples (monthly means of log (x+1) 3 transformed number per 1000 m ) at Seabrook intake (P2), discharge (PS) and farfield (P7). stations, July 1986-December 1992 . . . . . . . . . . . . . . . . . . . . . . .'5-14 3 5-4. Mean monthly log (x+1) abundance (no./1000 m ) in the pre-operational period (July 1975-July 1990, with:95% confidence limits), operational period, and 1992 for larvae of American. sand lance, winter flounder, Atlantic cod, and yellowtail flounder at nearfield Station P2 . . . . . . . . . . . . . . . . 5-18 5-5. Mean monthly log (x+1) abundance (no./1000 3m ) in tha pre - operational period (July 1975-July 1990, with 95% confidence limits), operational period, and 1992 for larvae of Atlantic mackerel, cunner, hake, Atlantic herring, and pollock at nearfield Station P2 . . . . . . . . . . . . . . . . . . . . 5-24 5-6. Total monthly cooling water system flow and estimated numbers of fish eggs and larvae encrained during the operational period . . 5-28 5-7. Annual total catch per unit effort (number per 24-hour set) in. gill nets by station and mean of stations, 1976-1992 . . . . . . . 5-29 5-8. Annual total catch per unit effort (mean number per 10 minute tow) in etter trawls by station and mean of stations, 1976-1992 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-32 5-9. Annual total catch per unit effort (mean number per haul) in beach seines by station and mean of stations, 1976-1992 . . . . . . 5-36 5-10. Log (x+1) catch per unit effort (number per 24-hr. set) for Atlantic herring, pollock and Atlantic mackerel; monthly means ) and 95% confidence intervals over all preoperational years l (1976-1989) and monthly means for the operational years 1 (1991-1992) and 1992 averaged over gill net Stations G1, j G2 and G3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-39 .) 5-111 l
PAGE 5-11. Log (x+1) catch per unit effort (mean number;per ten minute -l 1 tow) for Atlantic cod; monthly means and 95% confidence i intervals over all preoperational years (1976-1989) and j monthly means for the operational years (1991-1992) and 1 1992 at otter trawl Stations- T1, T2 and T3 . . . . . . . . . . . . 5-42 5-12. Log (x+1) catch per unit effort (mean number per 10 minute tow) for hake species and yellowtail flounder; monthly means and 95% confidence intervals over all preoperational years J (1976-1989) and monthly means for the operational years (1991-1992) and 1992 averaged over otter trawl Stations T1, T2 and T3 . . . . . . . . . . . . .. . . . . . . . . . . . . . 5-46 5-13. Log (x+1) catch per unit effort (mean number per ten minute tow) for winter flounder; monthly means and 95% confidence intervals over all preoperational years (1976-1989) and monthly mee.ns for the operational years (1991-1992) and 1992 at otter trawl Stations T1, T2 and T3 . . . . . . . . . . . . . . 5-48 5-14. Log (x+1) catch per unit effort (number per haul) for winter
-flounder, rainbow smelt and Atlantic silverside;. monthly means and 95% confidence intervals over all preoperational years (1976-1989) and monthly means for the operational years (1991-1992) and 1992 averaged over beach seine. Stations S1, S2 and S3 . . . . . . . . . . . . . . . . . . . . . . . . . . 5-50 5-15. Log (x+1) catch per unit effort (mean number per 10 minute tow) for rainbow smelt; monthly means and 95% confidence intervals over all preoperational years (1976-1989) and monthly means for the operational years (1991-1992) and 1992 averaged over otter trawl Stations T1, T2 and T3 . . , , . . . 5-52 5-16. Volume of cooling water pumped and fish impinged at Seabrook Station during 1991 and 1992 . .. . . . . . . . . . . . . . . . 5-55 5-iv i '.e
, c . . -
LIST OF TABLES PAGE l l 5-1. DESCRIPTION OF FINFISH SAMPLING STATIONS . . . . . . . . . . . . . 5-6 l 1
^
5-2. FREQUENCY OF OTTER TRAWL SAMPLES NOT COLLECTED AT STATION T2 DUE TO THE PRESENCE OF COMMERCIAL LOBSTER GEAR . . . . . . . . . 5-7 5-3. FAUNAL CHARACTERIZATION OF GROUPS FORMED BY NUMERICAL CLASSIFICATION OF SAMPLES OF FISH EGGS COLLECTED AT SEABROOK INTAKE (P2), DISCHARGE (PS), AND FARFIELD (P7) STATIONS DURING JULY 1986 THROUGH DECEMBER 1992 . . . . . . . . . 5-11 5-4 FAUNAL CHARACTERIZATION OF GROUPS FORMED BY NUMERICAL CLASSIFICATION OF SAMPLES OF FISH LARVAE COLLECTED AT SEABROOK INTAKE (P2), DISCHARGE (PS), AND FARFIELD (P7) STATIONS DURING JULY 1986 THROUGH DECEMBER 1992 . . . . . . . . . . 5-15 3 5-5. GEOMETRIC MEAN ABUNDANCE (No./1000 m ) AND 95% CONFIDENCE LIMITS OF SELECTED SPECIES OF FISH LARVAE AT STATIONS P2, PS, AND P7 OVER PREOPERATIONAL YEARS AND GEOMETRIC MEAN ABUNDANCE IN OPERATIONAL YEARS AND 1992 . . . . . . . . . . . . . . 5-19 5-6. RESULTS OF ANALYSIS OF VARIANCE
- OF LOG (x+1) TRANSFORMED 3
ABUNDANCES (No./1000 m ) 0F SELECTED SPECIES OF FISH' LARVAE AMONG STATIONS P2, PS, AND P7 DURING PREOPERATIONAL AND~ b OPERATIONAL PERIODS . . . . . . . . . . . . . . . . . . . . . . . 3-20 5-7. MONTHLY ESTIMATED NUMBERS OF FISH EGGS AND LARVAE ENTRAINED BY TEE COOLING WATER SYSTEM AT SEABROOK STATION DURING JANUARY THROUGH AUGUST AND DECEMBER 1992 . . . . . . . . . . . . . 5-27 5-8. GEOMETRIC HEAN CATCH PER UNIT EFFORT (NUMBER PER 24-HOUR SET, SURFACE AND BOTTOM) FOR ABUNDANT SPECIES COLLECTED IN GILL NETS AT STATIONS G1, G2 AND G3 COMBINED FOR THE PREOPERATIONAL PERIOD WITH 95% CONFIDENCE LIMITS, AND 1991, 1992 AND OPERATIONAL MEAN . . . . . . . . . . . . . . . . . . 5-29 5-9. GEOMETRIC HEAN CATCH PER UNIT EFFORT (NUMBER PER 24-HOUR SET, SURFACE AND BOTTOH) BY STATION FOR ABUNDANT SPECIES COLLECTED IN GILL NETS DURING THE PREOPERATIONAL PERIOD WITH 95% CONFIDENCE LIMITS, AND 1991, 1992 AND OPERA-TIONAL MEAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-31 5-10. GEOMETRIC MEAN CATCH PER UNIT EFFORT (NUMBER PER TEN-MINUTE TOW) FOR ABUNDANT SPECIES COLLECTED IN OTTER TRAWLS AT STATIONS T1,-T2 AND T3 COMBINED FOR THE PREOPERATIONAL PERIOD WITH'95%' CONFIDENCE LIMITS, 1991, 1992, AND OPERATIONAL MEAN . . . . . . . . . . . . . . . 5-32 5-v
l 1 I PAGE ! i 5-11. GE0 METRIC MEAN CATCH PER UNIT EFFORT (NUMBER PER 10 MINUTE TRAWL) BY STATION FOR ABUNDANT SPECIES COLLECTED IN O' ITER TRAWLS DURING THE PREOPERATIONAL PERIOD WITH t 95% CONFIDENCE LIMITS, AND 1991, 1992 AND OPERATIONAL MEAN . . . . 5-34 { i 5-12. GEOMETRIC MEAN CATCH PER UNIT EFFORT (NUMBER PER HAUL) l FOR THE TEN MOST ABUNDANT SPECIES COLLECTED IN BEACH . SEINES AT STATIONS S1, S2 AND S3 COMBINED FOR THE PREOPERATIONAL PERIOD WITH 95% CONFIDENCE LIMITS, AND j 1991, 1992 AND OPERATIONAL MEAN . . . . . . . . . . . . . . . . 5-36 j l I 5-13. GEOMETRIC MEAN CATCH PER UNIT EFFORT (NUMBER PER HAUL) BY STATION FOR THE TEN MOST MOST ABUNDANT SPECIES COLLECTED IN BEACH SEINES FOR THE PREOPERATIONAL PERIOD WITH 95% CONFIDENCE LIMITS, AND 1991, 1992 AND OPERATIONAL MEAN . . . . . . . . . . . . . . . . . . . . . . 5-37 ] l 5-14 RESULTS OF ANALYSIS OF VARIANCE COMPARING ABUNDANCES OF { I SELECTED SPECIES OF PELAGIC FISH AT ALL GILL NET STATIONS DURING PREOPERATIONAL AND OPERATIONAL PERIODS . . . . . . . . . . 5-40 5-15. RESULTS 07 ANALYSIS OF VARIANCE COMPARING ABUNDANCES OF SELECTED SPECIt'.S' 0F DEMERSAL FISH AT ALL TRAWL STATIONS ! DURING PREOPERATIONAL AND OPERATIONAL PERIODS . . . . . . . . . 5-43 l 5-16. RESULTS OF ANALYSIS OF VARIANCE COMPARING ABUNDANCES OF SELECTED SPECIES OF ESTUARINE FISH AT ALL BEACH SEINE STATIONS DURING PREOPERATIONAL AND OPERATIONAL PERIODS . . . . . . 5-51 5-17. NUMBER OF ORGANISMS IMPINGED AT SEABROOK STATION BY MONTH AND SPECIES DURING 1992 . . . . . . . . . . . . . . . . . . . . . . 5-53 5-18.
SUMMARY
OF POTENTIAL EFFECTS (BASED ON NUMERICAL CLASSIFI-CATION AND MANOVA RESULTS) 0F OPERATION OF SEABROOK STATION IKTAKE ON INDIGENOUS ICHTHYOPLANKTON COMMUNITIES . . . . . 5-56 5-19.
SUMMARY
OF POTENTIAL EFFECTS (BASED ON ANOVA RESULTS) 0F OPERATION OF SEABROOK STATION INTAKE ON ABUNDANCES OF SELECTED ICHTHYOPIJ4KTON SPECIES . . . . . . . . . . . . . . . . . 5-56 6 5-20. COMPARISON OF ENTRAINMENT ESTIMATES (x 10 ) AT NEW ENGLAND POWER PLANTS WITH MARINE INTAKES . . . . . . . . . . . . . . . . 5-58 5-21.
SUMMARY
OF POTENTIAL EFFECTS OF OPERATION OF SEABROOK STATION INTAKE ON ABUNDANCES OF PELAGIC FISHES . . . . . . . . . . 5-59 5-22.
SUMMARY
OF POTENTIAL PLANT EFFECTS ON ABUNDANCE OF DEMERSAL FISHES . . . . . . . . . . . . . . . . . . . . . . . 5-61 5-vi
l 4 PAGE 5-23.
SUMMARY
OF POTENTIAL PLANT EFFECTS ON ABUNDANCE OF 1 ESTUARINE FISilES . . . . . . . . . . . . . . . . . . . . . . . . 5-63 l 5-24. COMPARISON OF IMPINGEMENT AT NEW ENGLAND POWER PLANTS WITil MARINE INTAKES . . . . . . . . . . . . . . . . . . . . . . . 5-64 l LIST OF APPENDIX TABLES
-1 5-1. FINFISil SPECIES COMPOSITION BY LIFE STAGE AND GEAR, JULY 1975-DECEMBER 1992 , . . . . . . . . . . . . . .5-70
'l l
l l
.l l
l l l l l 5-vii !
FISH 5.0 FISH period was added to the months of Febru-ary- August and December beginning in July Common names recognized by the American 1977. A second sampling period was added , Fisheries Society (Robins et al.1991) are to the remaining months beginning in used for fish taxa. The common and January 1979. In March 1983, the sampling i scientific names for every taxon collected frequency was increased from twice per from 1975 through 1992 in the Seabrook month to the current frequency of four ichthyoplankton and adult finfish programs times per month. l are listed with their relative abundances , by gear type in Appendix Table 5-1. No Station P2 near Seabrook Station's species new to the Seabrook program were intake (Figure 5-1) was sampled throughout encountered during the 1992 surveys. the entire July 1975-December 1992 period. Station P5 near Seabrook Station's discharge was sampled during July 1975-5.1 OBJECTIVES December 1981 and during July 1986-December 1992. ' Station P7, located The objectives of the ichthyoplankton approximately 7 km north of the nearfield and adult fish investigations are to discharge zone was sampled to delineate determine the seasonal, annual, and the farfield ichthyoplankton commnity spatial trends in the distribution of during January 1982-December 1984 and eggs, larvae and adult fish in the during January 1986-December 1992. nearshore waters off Hampton and Seabrook, NH, and for adult fish only, in the On each sampling date and at each Hampton River estuary. In addition, the station, four samples were collected at , objectives are to determine the number and night. Samples were paired oblique tows l species of adult fish impinged at Seabrook with 1-m diameter, 0.505-mm mesh nets. l Station, and of fish eggs and larvae Each net, with an 8-kg (17.6-lb) depres- I entrained by Seabrook Station. The goal sor, was set off the stern and towed for I is to determine if the operation of 10 minutes while varying the boat speed, Seabrook Station has any measurable ef fect causing the nets to sink to approximately ; on the nearshore fish populations. 2 m off the bottom and to rise obliquely l to the surface at least twice during the i tow. The standard 10-minute tows were 5.2 tifJ110D3 occasionally reduced to five-minute tows to minimize net clogging due to high 5.2.1 Ichthvoolankton plankton density. The volume filtered, calculated using data from a calibrated l 5.2.1.1 Offshore Samoling General Oceanics@ flowmeter mounted in l each net mouth, averaged approximately 500 Ichthyoplankton sampling was conducted m3 for 10-minute tows and approximately 3 from July 1975 through December 1992. 250 m for five-minute tows. Upon retriev-Sampling was initially conducted monthly al, each net was washed down from mouth (July 1975-June 1976). A second sampling 5-1
1 l i FISil { l N ****%
. . .- - :: ngte
_ ,n
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?' , .
anga.a , j
~-
= .
i 2p , j,' ,, ' acwo ;
**g .. j _ , - e . u.,,. r l
e er i! Juwino amsog
- t *= w a i y mi- _,,,y,,
'NIE?of '
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, Ay / .
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(, ; i i { f Figure 51. Ichthyoplankton and adult fish sampling stations. I b Seabrook Operational Report,1992.' )
' to cod end and the contents preserved in Samples were taken using a double barrel 5% formalin buffered with borax. collection system. A 0.505-mm mesh plank- l ton net was suspended in a 30 gallon drum which, in turn, was suspended in a 55-5.2.1.2 Entrainment Sa!Daling gallon drum. Water diverted from the cooling water system entered the 55 gallon Ichthyoplankton entrainment sampling was drum from the bottom, overflowed the 30-conducted up to four times a month by gallon drum into the plankton not. After NAESCO personnel within the circulating parsing through the not, the water dis-water pumphouse on-site at Seabrook charge.1 through the bottom of both drums.
Station during July 1986-June 1987 and The wr er supply was adjusted to maintain June 1990-December 1992. Sampling dates three to six inches of water above the coincided with of fshore ichthyoplankton plankton nu. st all times. Four of these ( sampling whenever possible. Three double d r u.. collectors were operated replicate samples were collected during simultaneously. Following sampling, water , each sampling date. Entrainment sampling was drained from the system and the was not conducted on several scheduled contents of the four nets were consolidat-sampling dates, due to either plant ed, placed in one sample jar, and pre-outages or sampling equipment problems. served with 5% buffered formalin. The The entrainment data discussed in this volume filtered was measured with an in-report are only those for the operational line flowmeter and averaged approximately pe r-f od . 100 m3 per replicate, f 5-2
FISH
-5.2.1.3 Laboratory Methods 5.2.1.4 Analvtical Methods Beginning in March 1983, only two of the Community structure of the ichthyo-four offshore samples, one from each pair, plankton was investigated with numerical were analyzed from each station for each classification to determine whether sampling date. The remaining two were species composition changed between the held as contingency samples. Prior to preoperational period (July 1990 and March 1983, all four samples per date and earlier) and the operational period station were analyzed. From January (August 1990 and later). Log (x+1) through December 1982, only one sample per transformed densities (number per 1000 m3 )
date and station was completely analyzed; of eggs and larvae were analyzed separate-only selected taxa were counted from the ly, remaining three samples. The data sets were reduced by (1) Samples were subsampled with a Folsom averaging dates within month, (2) in-plankton splitter and sorted for fish eggs cluding only the more abundant taxa, and and larvae using a dissecting microscope. (3) limiting the analysis to data col-Successive aliquots were analyzed until lected since July 1986, when all- three a minimum of 200 eggs and 100 larvae were stations of concern were sampled. Rare sorted or until 200-400 mi settled taxa were excluded on the basis of percent plankton volume was sorted. All eggs and composition (less than 0.1%) or frequency larvae were identified to the lowest of occurrence (less than 5%). One month, practical taxon (usually species) and March 1989, was excluded from the egg counted. Some eggs that were difficult analysis because the counts were too low to identify to species were grouped with to provide a meaningful measure of species eggs of similar appearance (e.g. , cunner c.omposition (fewer than 20 per station). (Tautogolabrus adspersus) and tautog The analysis used the Bray-Curtis similar-(Tautoga onit/s) were grouped with yel- ity index (Clifford and Stephenson 1975) lowtail flounder (Pleuronectes ferru- and the unweighted pair group clustering gineus) and termed Labridae/Pleuronecces method (Sneath and Sokal 1973). The
- eggs]. Numbers were then converted to a resulting dendrograms were evaluated on standard density (no./1000 m 3). At least the basis of whether samples from the 20 larvae per sample (if present) were operational period were grouped different-measured to the nearest half millimeter ly by the analysis than were the preopera-notochord length for each of nine selected tional samples.
species. Multivariate analysis of variance All entrainment replicates collected (MANOVA, Harris 1985) was also used to were analyzed frem each sampling date. Indicate whether community composition Sample analysis for entrainment samples differed between preoperational and was identical to that used for offshore operational periods. The analysis was samples. restricted to collections from July 1986-December 1992, the common period of 5-3 i
- -. . - . - - - - - .- . _ - - ~ _ ..
FISH sampling at Stations P2, P5 and P7. The significant but the Preop-Op X Station l same species that were analyzed by interaction term was not, it meant that l numerical classification were included, densities had changed equally at all and individual sampling dates were used stations between the preoperational and (without first averaging within month). operational periods. The Wilks' lambda statistic was used to evaluate shif ts in log (x+1) transformed Geometric means and ANOVA were calculat-densities between preoperational and ed using only the months of peak abundance operational periods, for each selected species. This peak period was defined for each. species as Larvae of nine selected species were those three or four months that usually individually evaluated for temporal and encompassed at least 90% of the annual . spatial changes in abundance between the abundance for this very highly seasonal preoperational and operational periods. life stage. Densities in the remaining Seasonal patterns of abundance were eight or nine months were primarily zero, ! graphically examined by comparing averages and they were excluded so their uniformly of log (x+1) transformed densities of each low values would not overwhelm the pat-month of the year for the preoperational torns present in the principal season of period, the operational period, and for occurrence. 1992 alone. Geometric means were compared among the preoperational, operational, and Entrainment results were examined for 1992 periods at the intake, discharge, and the operational period only. Entrainment f arfield stations. Sampling periods were results for July 1986-June 1987 (prior to averaged within month before averaging commercial operation) were presented in months or years together. This practice the 1987 baseline report (NAI 1988). > weighted each month or year equally in Densities of eggs and larvae in entrain-cases where the number of collections ment samples were multiplied by the varied among months or years, month's average daily volume pumped through the Circulating Water System, and Analysis of variance (ANOVA) was used by the number of days represented by each to evaluate spatial and temporal variabil- sampling date, and then summed within ity and to test the null hypothesis that month to estimate the number of ichthyo-values collected during the operational plankters entrained by Seabrook Station period were not significantly different on a monthly basis. No entrainment from the preoperational period. ANOVAs estimates were made for the August-were restricted to the July 1986-December November 1991 or September-November 1992 1992 period, so that the same years were periods, when sampling was suspended due l represented at each station. The ANOVA to plant outage, factor of principal interest was the , Preop-Op X Station interaction term, where I Preop-Op is a class variable with two val- l uos, representing preoperational and operational periods. If Preop-Op was 5-4
FISH
~
5.2.2 Adult Fish It was not always possible to collect samples at Station T2 due to the presence 5.2.2.1 Pelarie Fish CommunitJ of commercial lobster gear. The frequency of missed samples has increased since 1983 Gill nets were set for two consecutive (Table 5-2). During the operational j 24-hour periods twice each month at period, no samples were collected at l Stations G1 (farfield), G2 (nearfield) and Station T2 during September and October G3 (f arfield) beginning in July 1975 to of 1990, August through October of 1991, sample the pelagic fish community (Figure and October of 1992. l 5-1; Table 5-1) . Sampling was changed to once per month in July 1986. Nets were 30.5 m x 3. 7 m and comprised four panels 5.2.2.3 Estuarine Fish Community having stretch mesh dimensions of 2.5 cm, . 10.2 cm and 15.2 cm. One not array Seine samples were taken monthly from consisting of surface and near-bottom nets April to November at Stations S1, S2 and was set at each station. All nets were S3 beginning in July 1975 (Figure 5-1; set perpendicular to the isobath (Figure Table 5-1). Duplicate daytime hauls were 5-1). Additionally, one gill not per taken into the tidal current at each station was set at mid-depth in February, station with a 30.5 m x 2.4 m bag seine. ( ' ' June and October. All nets were attached The nylon bag was 4.3 m x 2.4 m with 1.4 between permanent mooring and tended daily em stretch mesh, and each wing was 13.1 by SCUBA divers. m x 2.4 m with 2.5 cm stretch mesh. 5.2.2.2 Demersal Fish Community 5.2.2.4 Imoincement The inshore groundfish community was Fish impinged at Seabrook Station were sampled monthly beginning in July 1975. collected af ter being washed from the 1/8" Sampling frequency was increased to twice traveling screens within the circulating per month in January 1985. Trawling was water pumphouse. Traveling screens were conducted at night along Stations T1, T2, washed weekly (K. Dow, YAEC, pers. comm. ) and T3 (Figure 5-1; Table 5-1) with a 9.8- and impinged fish were sluiced into a m shrimp trawl (3.8-cm nylon stretch mesh collection basket. Fish from weekly body; 3.2-cm stretch mesh trawl bag;1.3-cm collections were separated from debris, stretch mesh cod end liner). Two repli- placed in dated plastic bags and frozen. cates were taken at each of the three sta- On a periodic basis, samples were thawed, tions. The net was towed at approximately identified to species, and counted. Data - 1 m/s for 10 minutes, with successive tows were provided by North Atlantic Energy taken in opposite directions. The volume Service Corporation. of drift algae caught in the trawl was recorded. l l 5-5
FISH. TABLE 5-1. DESCRIPTION OF FINFISH SAMPLING STATIONS. SEABROOK OPERATIONAL REPORT,1992. STATION DEPTH BOTT0H TYPE REMARKS BEACH SEINES S1 0-2 m s and Affected by tidal currents; approximately 300 m upriver from Hampton Beach Marina. S2 0-1 m sand Affected by tidal currents; approximately 200 m upstream from the mouth of the Browns River. S3 0-3 m sand Affected by tidal currents; located in Seabrook Harbor, approximately 300 m from Hampton Harbor Bridge. GILL NETS G1 20 m sand Seaward from rocky out-cropping off Seabrook. G2 17 m sand Seaward of Inner Sunk Rocks. G3 17 m rock / cobble Offshore from Great Boars Head. OTTER TRAWLS T1 20-28 m sand Transect begins 0.5 miles southeast of Breaking Rocks Nun, 150-200 m from submerged rock outcroppings. T2 15-17-m sand, drift 100 m from Inner Sunk Rocks, algae w/shell scoured by tidal currents; debris large quantities of drift algae. T3 22-30 m sandy; littered Located off Great Boars with shall Head; just seaward of a debris cobble area (rocks 15 ' l 50 cm diameters). 5-6
FISH TABLE 5-2. FREQUENCY OF OTTER TRAWL SAMPLES NOT COLLECTED AT STATION T2
'DUE TO THE PRESENCE OF COMMERCIAL LOBSTER GEAR. SEABROOK OPERATIONAL REPORT, 1992.
l 1 NUMBER OF SAMPLES HONTH YEAR NOT COLLECTED 1 October 1983 1 November 1983 1 September 1985 l' August 1986 2 September 1986 2 October 1986 2 September 1988 2 October 1988 2 September 1989 t 2 October 1989 b 2 September 1990 2 October 1990 2 August 1991 2 September 1991 2 October 1991 1 September 1992 2 October 1992
" Frequency of sample collection increased to two dates per month in July 1986. i b
Seabrook Station became operational in August 1990. l l 1 1 1 5.2.2.5 Anahtthal Methods per unit effort (CPUE). The standard units were one 24-hour set for gill nets, Fish collected in gill nets, trawls and one ten-minute tow for the otter trawl, j seinen were identified to species, and one haul for beach seines. Data were j measured and grouped into 2 cm size tabulated separately for each transect or classes. Fish that were difficult to station and for each depth for the gill identify in the field such as hakes nets. CPUE data were log (x+1) transformed (Urophycis spp.), skates (Rajo app.), and all operations were performed on the sna11 fishes (Liparis spp.), and mummichogs trans formed data. The log (x+1) transfor- l and striped killifish (Tundulus spp.) were mation was employed because it allows for grouped by genus. O values to be used to normalize posi-tively skewed frequency distributions Catch data from each of the three types (Sokal and Rohlf 1981). Transformed means of fishing gear were standardized to catch were back transformed for presentation in S-1
1 FISH l 1 i tables and figures as geometric means, spatial differences in CPUE for the ) Geometric means are generally lower than selected species. Details of the ANOVA i arithmetic means as outliers have less model used are found in NAI (1992). Main l influence on a geometric mean. Thus, a effects tested included the operational ! geometric mean is a weighted mean in which status of Seabrook Station (preoperational . extreme values are given less weight than versus operational), sampling station values closer to the center of the (nearfield and farfield) and the interac-distribution. Differences in the pelagic, tion between operational status' and demersal and estuarine fish communities sampling station. A significant interac-between the preoperational and operational tion term was considered to indicate a periods, and among stations were analyzed potential impact due to the operation of through comparisons of geometric mean Seabrook Station (NAI 1992). Catch data CPUE. were subset to exclude months when-individual selected species were histori- . Seasonal, inter-annual and spatial cally not present, or catches were very variations in abundance were analyzed for variable. The remaining periods of low nine selected species. Selection of variation in CPUE were used in the ANOVA.- species was based on two criteria: (1) This method of subsetting the data was high abundance in at least one life stage conservative because it increased the and gear type; (2) importance in local power of the model to detect significant commercial or sport fisheries. The nine differences among years by decreasing selected species and their primary within-year variation. The year 1990 was collection methods were: classified as either preoperational,-or operational, or was excluded from the analysis for a species depending on that Species Gear True species' seasonal pattern of occurrence. If the months selected for analysis Atlantic herring gill nets included August (the month of plant Atlantic mackerel gill nets startup), collections from 1990 were Pollock gill nets eliminated from analysis. If the months Atlantic cod otter trawl selected occurred before August,1990 was Hakes (red, classified as preoperational; and if the white, spotted) e t.,r trawl months selected occurred af ter August, , Yellowtail flounder otter trawi 1990 was classified as operational. Vinter flounder otter trawl and
- beach seine The months of August through October Rainbow smelt otter trawl and were excluded from the analysis of vari-beach seine ance of trawl catches because often the Atlantic silverside beach seine only data available for this time period were from the farfield stations. .
l Analysis of variance (ANOVA) was used Impins: see collections were noted as to statistically test- for temporal and total co - ; per species by month. In 5-8
. . ... - --. - . .. - - - - . ~ - - . _ - -
FISII addition, the number of fish impinged per Eggg million gallons ' of cooling water was calculated. Numbers of fish impinged and Numerical classification of 231 monthly impingement rates were compared to other ichthyoplankton samples from three New England power plants with marine stations based on e.bundances of 11 domi-
-intakes, nant taxa of fish eggs resulted in eight major groups (Figure 5-2). Each group was characterized by its distinct species 5.3 RESULTS composition and abundances (Table 5-3).
Group 1 included collections from the late 5.3.1 Ichthyoolankton fall that were dominated by Atlantic cod / haddock eggs. Group 2 collections 5.3.1.1 Esmmunity were from the early winter and contained mostly Atlantic cod / haddock and pollock st o' the dominant pelagic and demer- eggs , in relatively low densities. Group adult finfish in the study area are 3 collections, from lat a winter, were also collected as larvae. Few, however, are characterized by low densities and identified in the egg stage either because Atlantic cod / haddock eggs, but American of difficult identifications (for example, plaice replaced pollock as the secondary Atlantic cod, yellowtail flounder, cunner, dominant. Group 4 collections were from and hake), or because several of these early spring and had higher densities of species do not produce pelagic eggs (for American plaice and Atlantic cod / haddock xample, American sand lance, winter eggs, and typically some fourboard
- lounder, and Atlantic herring). rockling eggs as well. Group 5 collec-tions, from the mid-spring, featured much The nearfield ichthyoplankton community higher egg densities as well as increased ,
has been examined in annual baseline diversity. They were dominated by reports using numerical classification cunner /yellowtail flounder, fourbeard (NAI 1982, 1983, 1984, 1985) and discri- rockling, American plalce, and Atlantic minant analysis (NAI 1987, 1988, 1989, mackerel. Group 6 collections were from 1990). Species composition of both eggs late spring and early summer and were and larvae exhibited distinct seasonal primarily characterized by very high changes that were consistent among years. densities of cunner /yellowtail flounder In the first two operational reports (NAI eggs. Group 7 collections were from the 1991, 1992), numerical classification summer months, and were generally charac-(cluster analysis) demonstrated that tbn terized by hake or hake /fourbeard rockling 1990 and 1991 communities followed the eggs, with smaller densities of cunner / same seasonal patterns observed ir pre- yellowtail flounder and windowpane. Group vious years. This year the corr . unity 8 >11ections were from the' fall when egg analysis of fish eggs and larvae again densities were lower. The primary taxa l uses numerical classification, and its present were ' Atlantic cod / haddock, I focus includes a comparison of intake, hake /fourbeard rockling, hake, Atlantic q discharge, and farfield stations, whiting, or fourbeard rockling. 5-9 l l l
, . . . , -1
, n , . - - ,. . .~ . . - ~ . . - - .. - . ., ~. --
"****- 8 UP i
4-g 4 4)
,---k f number of samples Group 1. Late Fall e
between group similarity ( R!n 0 , . , , , . , . , . . , , , , 20 ", e '##l Group 2. Early Winter
>?i:e?r?ola:olr sto?.
[!!!!!!!!!!:i Group 3. Late Winter Group 4 - Early Spring
*h*^a^;l*'
.. Group 5.Mid Spring
_ Group 6 Late Spring / Early Summer Group 7 Summer Group 8. Early Fall .. 0!0 O!2 O!4 O!6 O!8 1.0 BRAY CURTIS SIMILARITY 1992 P2_ P5_ li'i',l,lj see s ,e e - l.a.;
/
[ ,'- j u Group 1 ,
. . ? - Group 2 1991 P5_;[elr[e[ ; Q E Group 3 M sssss . . . ; .s a P2 .'i'i'i'1' jjj"j .,*.* '
$ Group 4 1996 1 u -* a *- // '
P5-'\e/ P7 e' ' 's ,.a. 6 s
,* . . = /// = 0
- Group 5 pT s vvc, #
y 1989 P5 'h .x . ( 'j @ Groop6 P7 'g es ejj, , . . 7. p7 rjyse ,e s g .a.a. o Group 7 p1 l - E . Group 8 PL'/,J,f/j
, .l*la d
O u ungrouped 1987 P5_,;,;,;,',; . .a F7 . e. e. e. e. *
.a. y g NS not sampled P2 x 1986 P5 p7 NS x g/ .:
a gp
, x excluded from analysis J'F'M'A'M'J -
=J A'S O N'D MONTH j Figult 5 2. Dendrogram and temporal / spatial occurrence pattem of fish egg assemblages j formed by numerical classification ofichthyoplankton samples (monthly means - '
of log (x+1) transformed number per 1000 mi) at Seabmok intake (P2), discharge (PS), and farfield (P7) stations, July 1986-December 1992. Seabrook Operational
. Report,1992.
5-10 w, . ..- .- . - - . . , . , - . .- .-. .. . , . -
TABLE 5-3. FAUNAL CHARACTERIZATION OF GROUPS FORMED BY NUMERICAL. CLASSIFICATION OF SAMPLES OF FISH EGGS COLLECTED AT SEABROOK INTAKE (P2), DISCHARGE (PS), AND FARFIELD (P7) STATIONS DURING JULY 1986 THROUGH DECEMBER 1992.* SEABROOK OPERATIONAL REPORT, 1992. NUMBER OF SAMPLES AND DENSITY (EGGS /1000 m3 )d PREOPERATIONAL PERIOD" OPERATIONAL PERIOD
- GROUP DOMINANT TAXAC n LCL MEAN UCL n LCL MEAN. UCL 1 Late Fall Atlantic cod / haddock 27 68 90 119 16 42 58 82 (0.73/0.49)b 2 Early Winter Atlantic cod / haddock 20 5 7 8 13 3 5 7 (0.60/0.59) pollock <1 1 2 <1 1 2 3 Late Winter Atlantic cod / haddock 5 5 9 16 6 3 6 13 (0.74/0.59) American plaice 2 3 4 5 6 9 4 Early Spring American plaice 15 22 38 64 6 46 164 585 (0.56/0.34) Atlantic cod / haddock 7 15 30 27 39 57
,. fourbeard rockling 4 8 16 0 <1 1 h 5 Mid-Spring cunner /yellowtail flounder 12 175 293 488 6 259 589 1,340 (0.76/0.55) fourbeard rockling 77 235 715 32 66 138 American plaice 54 73 97 58 96 158 Atlantic mackerel 18 37 77 237 527 1,170 6 Late Spring / cunner /yellowtail flounder 30 5,680 9,800 16,900 15 5,470 10,100 18,500 Early Summer (0.72/0.64) 7 Summer hake 24 143 204 291 15 100 228 519 (0.74/0.64) hake /fourbeard rockling 131 242 447 106 185 321 cunner /yellowtail flounder 17 45 113 16 58 207 windowpane 29 53 94 87 131 198 8 Early Fall Atlantic cod / haddock 9 10 20 39 9 1 4 11 (0.67/0.42) hake /fourbeard rockling 4 10 25 4 9 19 hake 6 10 17 2 4 7 Atlantic whiting 5 8 12 8 16 31 fourbeard rockling 1 4 10 <1 1 1
*Each " sample" consisted of the average of tows within date and dates within month.
b(Within group /between group similarity) , Those whose preoperational geometric mean densities together accounted for 290% of the sum of the preoperational geometric mean densities of all' taxa within the group. d Geometric mean and lower (LCL) and upper (UCL) 95% confidence limits.
*Preoperational = July 1986 - July 1990; Operational = August 1990 - December 1992.
FISH The temporal and spatial distribution The pattern of seasonal succession of of samples among'the groups (lower part the eight fish egg assemblages identified of Figure 5-2) indicates the extent to by this analysis remained consistent from which changes in the composition of the year to year, and the period following the fish eggs community correspond to any of initiation of commercial operation in the f actors in the sampling design (plant August 1990 agreed very well with the operational status, month, year, or pattern in previous years (Figure 5-2), station). Tne time of year was clearly The August 1992 samples indicated a the only factor that was related to the slightly longer persistence of the Group changes in species assemblages among the 6 late spring-early summer cunner / groups, as shown by the vertical patterns yellowtail flounder eggs assemblage than formed by the groups in the lower part of in five of the previous six years, but the figure. Each month's samples occurred transitions from one assemblage to another - in no more than three of the nine groups. have varied by one month in several Furthermore, each group consisted only of preoperational occasions as well (Figure samples from a brief season (one to four 5-2). Overall, the species composition months). In contrast to the factor of and abundance of fish eggs have been very month, the factors of plant operational consistent between the preoperational and . status, year, and station were unrelated operational periods. This conclusion is to group assignment: no group had a substantiated by the results of a multi-disproportionately high number of samples variate analysis of variance (MANOVA), from the preoperational period, the opera- which showed that although there was a tional period, any single year, or any detectable change in the egg community single station. This indicates that for between preoperational and operational any particular season, the species assem- periods (p<0.001), the difference was blages were similar among years, among consistent at nearfield and farfield stations, and between preoperational and stations (p>0.99). This result implies operational periods, that there were some among-year differ-ences in the fish egg community as a Samples from dif ferent stations col- whole, but because they were not limited lected in the same month tended to occur to nearfield stations, there is no evi-in the same sample group, indicating a dence t. hat they are related to plant nigh degree of similarity of fish eggs operation. The most notable dif ferences assemblages among the three stations. In between preoperational and operational 90% of the months in the analysis, periods were decreased densities of
-collections from all three stations were fourbeard rockling and pollock eggs in the classified in the same group (Figure 5-2). operational periods.
Furthermore, in 34% of the months,.high similarity levels in the collections from !' the three. stations caused them to group more closely with each other than with any of the other samples in the same group. I 5-12
FISH Larvae The limited number of months represented in each sample group (from one to three) Eight groups were identified from shows that the groups reflect highly numerical classification of 234 monthly consistent seasonal assemblages (Figure ichthyoplankton samples from three 5-3). In contrast, there was no tendency stations on the basis of abundances of 22 for samples to group selectively according dominant taxa of fish larvae (Figure 5-3). to plant operational status, year, or sta-Each group was characterized by a unique tion. Each group contained a represen-set of dominant species and their abun- tative selection of samples from both dances (Table 5-4). Group 1 collections preoperational and operational periods, were from the late fall and contained samples from several different years, and primarily Atlantic herring larvae. Group samples from all three stations. 2 collections were from the early winter and were dominated by American sand lance, In 97% of the months analyzed, all three , with lower densities of Atlantic herring, stations were classified into the same < gulf sna11 fish, and pollock. Group 3 sample group (Figure 5-3). In 39% of the contained late winter collections with months, the three stations not only fell high densities of American sand lance, and in the same group, but they were more rock gunnel as a secondary dominant. closely similar to each other than to any Group 4 collections, from the early other samples of their group. This l spring, featured American sand lance at underscores the similarity in species j somewhat reduced densities, and were composition among the three stations. secondarily characterized by Atlantic I seasnail, gulf snailfish, grubby, and rock Larval fish assemblages in the opera-gunnel, Group 5 was made up of mid-spring tional period (August 1990 and later) collections, which contained Atlantic followed the same seasonal progression as seasnail larvan in the greatest abundance, in preoperational years (Figure 5-3). followed by winter flounder, radiated Slight variations in the timing of the shanny, American sand lance, and American appearance of the various seasonal as- I plaico. Group 6 collect .ons were from semblages occurred among years within both i late spring and early summer and were the preoperational and operational dominated by larvae of cunner, fourbeard periods, but the seasonal pattern in the rockling, radiated shanny, Atlantic operational period was consistent with the mackerel, and winter flounder. Group 7 usual preoperational pattern. The species collections, from the late summer, had composition in the operational period was high densities of cunner, and were also similar to that in the preoperational characterized by fourbeard rockling, hake, period, although average densities were and witch flounder larvae. Group 8 not always similar between preoperational ; collections were from the early fall and operational periods. For example, months, and contained relatively low Atlantic herring densities in the late larval densities, with fourbeard rockling fall (Group 1) decreased between - the predominating and several other species preoperational and operational periods, occasionally present in smaller numbers, whereas Atlantic mackerel densities in the 5-13 w- w - as- s .,ea >n---. -
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TABLE 5-4. FAUNAL CHARACTERIZATION OF GROUPS FORMED BY NUMERICAL CLASSIFICATION ~OF SAMPLES OF FISH LARVAE COLLECTLD AT SEABROOK INTAKE (P2), DISCHARGE (P5), AND FARFIELD (P7) STA-l TIONS DURING JULY 1986 THROUGH DECEMBER 1992.* SEABROOK OPERATIONAL REPORT, 1992. 3 NUMBER OF SAMPLES AND DENSITY (LARVAE /1000 m )d PREOPERATIONAL PERIOD
- OPERATIONAL PERIOD
- GROUP DOMINANT TAXAC n LCL MEAN UCL n LCL MEAN UCL 1 Late Fall Atlantic herring 30 29 50 84 21 6 12 21 (0. 25/0.16)b 2 Early Winter American sand lance 14 12 24 48 6 10 26 63 (0.53/0/48) Atlantic herring 2 4 8 <1 1 2 i gulf snailfish 2 4 6 2 3 5
,. pollock 1 3 8 1 3 4 3 Late Winter American sand lance 22 226 324 463 12 178 258 375 u (0.72/0.61) rock gunnel 23 37 58 18 37 75 i
.C 4 Early Spring American sand lance 17 51 80 125 6 32 58 105 (0.68/0.61) Atlantic seasnail 13 23 40 3 6 10 gulf snailfish 7 11 18 1 3 6 grubby 6 11 19 4 6 9 rock gunnel 6 10 17 1 3 5 5 Mid-Spring Atlantic seasnell 7 31 87 240 6 13 38 105 (0.63/0.37) winter flounder 6 18 51 2 5 14 radiated shanny 11 17 26 8 19 40 American sand lance 6 10 17 4 19 72 American plaice 4 7 13 5 8 12 6 Late Spring / cunner 30 52 116 254 12 3 19 87 Early Summer fourbeard rockling- 32 55 93 14 27 54 (0.58/0.45) radiated shanny 19 29 42 30 44 66 Atlantic mackerel 10 19 36 11 49 215 winter flounder 6 11 20 5 10 20 7 Late Summer cunner 12 69 146 306 12 140 467 1,550 (0.61/0.45) fourbeard rockling 19 51 132 25 38 59 hake 5 8 14 13 42 130 witch flounder 3 7 14 1 2 4 (continued)
.k u n re TABLE 5-4. (CONTINUED)
NUMBER OF SAMPLES AND DENSITY (LARVAE /1000 m3 )d PREOPERATIONAL PERIOD
- OPERATIONAL PERIOD
- GROUP DOMINANT TAXAh n LCL MEAN UCL n LCL MEAN UCL 8 Early Fall fourbeard rockling 15 1 3 5 12 3 5 9 (0.43/0.31) cunner 1 3 6 1 1 2 windowpane 1 1 2 <1 1 2 Atlantic herring <1 1 2 <1 <1 1 hake 1 1 2 <1 1 1 Atlantic whiting <1 1 2 <1 1 2 witch flounder <1 1 1 <1 1 2
*Each " sample" consisted of the average of tous within date and dates within month.
b(Within group /between group similarity).
*Those whose preoperational geometric mean densities together accounted for 190% of the sum of the Y' preoperational geometric mean densities of all taxa within the group.
g Geometric mean and lower (LCL) and upper (UCL) 95% confidence limits.
*Preoperational = July 1986 - July 1990; Operational = August 1990 - December 1992.
l l l
FISH 1 ate spring /early summer (Group 6) in- reason for the high within-year vari-creased between preoperational and oper- ability (NAI 1983). at.ional periods. Shifts in the larvae community composition such as this are reflected in a significant operational American Sand Lance status effect (p<0.001) in a MANOVA for this same data set. When the operational Historically, American sand lance larvae status vs. station interaction (Preop-Op were usually present in collections from X Station) is examined, however, it is December through June or July, with peak clear that any changes during the opera- abundances occurring from February through tional period were not limited to the April (Figure 5-4). The relatively long nearfield stations (p>0.99). This is an period of occurrence is due primarily to indication that changes in larval abun- an extended hatching period (Richards dances in the operational period were not 1982) and a long planktonic period for the related to plant operation, and it is larval stage (Bigelow and Schroeder 1953). likely that the significant difference Abundance during 1992 and the two-year between preoperational and operational operational period was 'very similar to fish larvae communities is due to long- abundance in the preoperational period in term trends. Of the 22 taxa in the most months, but lower than in the MANOVA, the greatest contributions to the preoperational period in March and April operational period shift in species (Figure 5-4) . American sand lance was the composition were decreased densities of most abundant species during both the Atlantic herring, gulf snailfish, and preoperational and operational period at Atlantic seasnail; and increased densities all stations (Table 5-5). Average of hake and Atlantic whiting. These were abundances in 1992 were lower than the area-wide changes not limited to the preoperational average at Station P2, but nearfield stations, were within the 95% confidence limits of the preoperational mean at Stations PS and P7. Analysis of variance indicated that 5.3.1.2 Selected Soccita one of the nearfield stations (PS) had significantly greater densities of larval The nine species of fish selected for American sand lance than at the farfield detailed analyses of within-year and station, but average densities were not among year patterns of larval abundance s ignificantly dif ferent between preopera-were either numerically dominant or im- tional (1986-1990) and operational periods portant as recreational or commercial (Table 5-6). species. Although larval fish were present in every month, each species exhibited a period of peak abundance of Winter Flounder three or four months and was usually absent for part of the year. These Winter flounder larvae, which ranked seasonal fluctuations were the primary fourth in abundance among the selected species during the preoperational period, 5-17
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FISH TABLE 5-5. 3 OE0HETRIC HEAN ABUNDANCE (No./1000 m ) AND 95% CONFIDENCE LIMITS
'0F SELECTED SPECIES OF FISH LARVAE AT STATIONS P2, PS, AND P7 OVER PREOPERATIONAL YEARS AND OE0HETRIC HEAN ABUNDANCE IN OPERATIONAL YEARS AND 1992. SEABROOK OPERATIONAL REPORT, 1992.
PREOPERATIONAL YEARS
- SPECIES OPERATIONAL (peak period) STATION LCL HEAN* UCL YEARSb 1992 American sand lance P2 106.8 159.6 238.1 80.3 98.2 (Jan-Apr) P5 129.7 225.4 391.2 148.0 173.9 P7 56.0 106.0 199.9 86.4 103.9 Winter flounder P2 9.0 12.1 16.0 6.4 7.5 (Apr-Jul) PS 7.5 10.5 14.7 6.4 8.6 P7 4.7 8.0 13.4 1.7 1.9 Atlantic cod P2 1.3 2.5 4.4 1.3 0.9 (Apr-Jul) PS 0.7 2.4 5.9 1.6 1.5 P7 0.3 1.0 2.1 0.8 0.7 Yellowtail flounder P2 1.9 3.4 5.8 1.2 1.3 (May-Aug) PS 2.8 5.0 8.3 1.2 1.5 P7 1.2 2.9 5.7 1.2 1.6 Atlantic mackerel P2 4.5 6.9 10.4 8.8 1.9 (May-Aug) PS 2.6 6.8 16.0 5.8 1.3 P7 3.8 5.9 9.1 9.6 2.7 Cunner P2 28.9 48.5 81.0 22,6 4.2 (Jun-Sep) P5 22.0 55.0 135.5 20.5 4.6 P7 23.9 59.0 143.9 28.5 5.2 Hake P2 2.4 3.9 6.2 0.9 0.2 (Jul-Sep) P5 1.6 3.1 5.6 1.7 0.2 P7 1.4 3.9 9.0 2.7 0.1 Atlantic herring P2 14.8 29.0 55.9 6.4 5.4 (Oct-Dec) PS 11.0 28.8 73.2 8.2 5.7 P7 15.8 33.2 68.5 10.1 15.7 Pollock P2 3.2 6.3 11.6 1.0 b (Nov-Feb) PS 3.0 8.2 19.9 1.4 b P7 0.8 2.4 5.6 0.7 b
*Preoperational years:
P2 = Jul 1975-Jul 1990 PS = Jul 1975-Dec 1981 and Jul 1986-Jul 1990 P7 = Jan 1982-Dec 1984 and Jan 1986-Jul 1990 (Years in which one or more months of the peak period were not sampled at a station were not included in the mean) b Yearly mean not computed for pollock in 1992 because January and February 1993 data were not available. 5-19
t TABLE 5-6. 3 RESULTS OF ANALYSIS OF VARIANCE OF LOG (x+1) TRANSFORMED ABUNDANCES (No./1000 m ) OF SELECTED SPECIES OF FISH LARVAE AMONG STATIONS P2, PS, AND P7 DURING PREOPERATIONAL AND OPERATIONAL PERIODS. SEABROOK OPERATIONAL REPORT, 1992. MULTIPLE COMPARISONS 9 (Ranked in SPECIES
- SOURCE OF decreasing (peak period) VARIATION df SS F order)
American sand lance Preop-Op 3 0. D 0.M M (Jan-Apr) Year (Preop-O 4 3.24 1.59 NS Month (. Year) p)d 18 71.70 7.80*** Station 2 4.09 4.00* P5 P2 P7
- Preop X Station i 2 1.22 1.19 NS Error 242 123.57 Winter flounder Preop-Op 1 2.90 8.22** Preop >Op
. (Apr-Jul) Year (Preop-O 4 5.33 3.78** Month (Year) p) 18 88.88 14.00*** Station 2 5.50 7.79*** P2 P5 P7 Preop X Station 2 0.98 1.39 NS i Error 248 87.49 w
,, Atlantic cod Preop-Op 1 1.88 14.83*** Op> Preop ,
o (Apr-Jul) Year (Preop-Op) 4 1.31 2.59* Month (Year) 18 11.16 4.89*** Station 2 0.56 2.22 NS Preop X Station 2 0.14 0.55 NS Error 248 31.47 Yellowtail founder 1 1.43 5.03* Preop >Op (May-Aug) Preop (-Op Year Preop O 3 3.59 4.20** , Month (Year) p) 15 29.87 7.00*** Station 2 t 0.21 0.36 NS Preop X Station 2 0.22 0.39 NS ; Error 216 61.48 Atlantic mackerel Preop-Op 1 2.65 3.90* Op> Preop (May-Aug) Year (Preop-O 3 27.20 13.34*** Month (Year) p) 15 147.42 14.46*** Station 2 0.45 0.33 NS Preop X Station 2 0.41 0.30 NS Error 216 146.80 (continued)
. _ ___m - _ _ -- -_ _ _ _ _ _ _ _ _ - _ . _ _ _ . _ _
TABLE 5-6. (Coatiaued) MULTIPLE COMPARISONS 9 (Ranked in SPECIES
- SOURCE OF decreasing (peak period) VARIATION df SS P order)
Cunner Preop-Op 1 23.00 35.53*** Preep>0p (Jun-Sep) Year (Preop-O 3 47.95 24.69*** Month (Year) p) 15 138.65 14.28*** Station 2 0.67 0.51 NS Preop X Station 2 0.07 0.05 NS Error 216 139.81 Hake Preop-Op 1 0.88 2.05 NS (Jul-Sep). Year (Preop-Op) 4 15.55 9.11*** Month (Year) 12 28.05 5.48*** Station 2 1.29 1.52 NS Preop X Station 2 0.57 0.66 NS w Error 194 82.80 Z Atlantic herring Preop-Op 1 21.95 53.14*** Preop >Op (Oct-Dec) Year (Preop-O 5 25.49 12.34*** Month (Year) p) 14 61.42 10.62*** Station 2 0.60 0.72 NS Preop X Station 2 0.41 0.49 NS Error 218 90.05 Pollock Preop-Op 1 3.89 22.89*** Preop >0p (Nov-Feb) Year (Preop-O 4 13.15 19.37*** Month (Year) p) 18 17.64 5.77*** Station 2 0.67 1.98 NS Preop X Station 2 0.05 0.15 NS Error 254 43.13
*b Based on each species' peak period as defined in Table 5-5 Preoperational = July 1986 - July 1990; Operational = August 1990 - December 1992; 1990 data were not included in the analysis for species where the period of peak abundance includes both July and August (e.g., yellowtail flounder)
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%reoperational ear nested withinversus operational and preoperational period regardless operational of station periods, regardless of statiod j *ponth nested within year nested within preoperational and operational periods, regardless of station
! Interaction between main effects (status and station) l 9 Underlining indicates no significant difference in least squares means at alpha 5 0.05. i NS = Not significant ( 0.05)
* = Significant (0.05 0.01)
** = Highly significant (0.012
*** = Very highly significant (p>0.001) ps0.001) i
F_ISil were usually present from April through larval Atlantic cod in 1992 and during the July, with the greatest abundance occur- operational period were lower than in the ring in May and June (Figure 5-4). Very preoperational period in most months, but few specimens were caught during August exhibited the same bimodal pattern. The through March. The season of occurrence average abundance in 1992 was lower than in 1992 and during the operational period the average abundance in 1991 and during was generally similar to that of the pre- the preoperational period at all three operational period, except that the stations (Table 5-5, NAI 1992). Analysis occurrence began later. Abundance in 1992 of variance indicated that mean abundance was lower in April and May, and higher in was higher during the two operational July compared to the preoperational period years than in the last four years of the (Figure 5-4). Average abundance of larval preoperational period and this pattern was winter flounder was lower at all stations consistent at all three stations (P2, PS, in 1992 and during the operational period P7) (Table 5-6). When earlier preopera-l than during the preoperational period tional years are included in the compari-(Table 5-5) . Densities of winter flounder son, however, the preoperational densities larvae have been variable from year to were greater (Table 5-5). year, so the lower values during the operational years are not necessarily indicative of negative effects due to Yellowtail Flounder Seabrook Station. The operational period's annual geometric mean densities Yellowtail flounder larvae were usually 3 of 5.5 larvae /1000 m in 1991 and 7,5 collected from May through September, with larvae /1000 m 3 in 1992 were within the peak abundance occurring in June and July range of values for the preoperational (Figure 5-4). Monthly abundance of years, which varied from 2.9 larvae /1000 yellowtail flounder larvae in 1992 and m3 in 1981 to 22.4 larvae /1000 m3 in 1985 during the operational period was lower (NAI 1991). The ANOVA results indicated than during the preoperational period, that not only was the average preopera- except in July, when abundance in 1992 and tional abundance greater than operational, for the operational period was slightly but abundance at the nearfield stations higher than in earlier years. The average (P2 and PS) was higher than abundance at abundance for the peak period in 1992 and ; the farfield station (P7) (Table 5-6). for the two-year operational period was lower than the preoperational average at all three stations (Table 5-5).- No Atlantle Cod significant differences were detected among nearfield and farfield stations 1 Atlantic cod larvae typically exhibited (Table 5-6). a bimodal period of occurrence with one l peak lasting from November through February and a second, usually larger pepk, lasting from April through July (Figure 5-4). Monthly abundances of i 5-22 l
FISH Atlantic Mackerel preoperational period (Table 5-5). ANOVA results indicated this difference was sig-Atlantic mackerel larvae have histori- nificant and there were no significant cally exhibited a period of occurrence differences among stations (Table 5-6). lasting from May through August or Sep-tomber with greatest densities occurring in June and July (Figure 5-5). The period liakn of occurrence has remained similar during the operational period, although monthly During the preoperational period, hake mean densities during the peak period were larvae have been confined to a relatively substantially higher in 1991 (NAI 1992) brief period of occurrence, beginning in and lower in 1992 (Figure 5-5) than the June or July, peaking in August and preoperational mean. As a result, the September, then declining to near zero by average abundance in 1992 for the peak- November (Figure 5-5) . Although generally period was substantially lower than the similar to the historical pattern, preoperational mean at all three stations, seasonal patterns during the operational although the operational mean abundance period have been highly variable over the was generally comparable (Table 5-5), three years studied. As hake larvae may However, analysis of variance indicated include more than one species, seasonal that mean abundance was statistically trends may be more variable than for a 8 renter during operational years 1991-1992 single species. Hake densities in 1990 than during the recent preoperational were much higher than in previous years years 1987-1989 (Table 5-6). There was (NAI 1991), whereas densities in 1992 were no significant difference in abundance exceptionally low (Table 5-5, Figure 5-5), among the three stations (Table 5-6). In a month by month comparison of opera- I tional and preoperational period densities (Figure 5-5) the high 1990 densities Gunnsu: usually balanced the low 1992 densities, .! yielding operational period densities that Cunner larvae have historically been were similar to the preoperational period collected primarily from June through densities in most months. Only in July, September, with peak abundance during July when the strong 1990 year class fell into and August (Figure 5-5). Abundances the preoperational period, were the during the operational period generally operational period densities substantially followed this same pattern, although the lower than in the preoperational period 1992 densities were much lower than usual, (Figure 5-5). When annual means were particularly during August and September. compared between preoperational and' As a result, average peak period abundance operational periods (Tables 5-5 and 5-6), in 1992 was less than the lower 95'4 1990 was excluded becaune it fell partly confidence limit of the preoperational in the preoperational period'and partly mean at all three stations. Mean abun- in the operational period. In the absence dance at all stations during the opera- of those high 1990 densities, the opera-tional period was lower than during the tional mean densities of hake larvae were 5-23 i
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JAN IES MAR Am MAY JUN Et AUG SEP OCf NOV DEC MONTu Figure 5 5. Mean monthly log (x+1) abundance (no/1000 m8)in the preoperational period (July 1975. July 1990, with 95% confidence limits), operational period, and 1992 i forlarvae of Atlantic mackerel, cunner, hake, Atlantic herring, and pollock at nearfield Station P2 Seabrook Operational Report,1992. 5-24 l l
l l FISH 1 I substantially lower than the preopera- from November though February and few to l tional mean derisities at all three none were caught from March through ! stations due to the low 1992 densities. October (Figure 5-5). However, monthly I pollock catches during the preoperational However, the difference between operation-al and recent (1987-1989) preoperational period were highly variable from year to was not statistically significant, year, as evidenced by the broad confidence Significant differences were noted among limits (Figure 5-5). Densities of larval years at months (Table 5-6). pollock were also irregular during the operational years. Monthly mean densities in 1992 were lower than average from Atlantic IIerring January-March and October-December. Average monthly densities during the Atlantic herring larvae typically operational period were higher than usual occurred from October through May and were during May but lower than usual in Decem-rare for the remainder of the year (Figure ber, Geometric mean abundance for the 5-5). Peak abundance usually occurred 1990-91 and 1991-92 peak periods was lower from October through December but a than the preoperational mean, but this second, smaller peak was commonly observed pattern was consistent among all stations in March. A similar pattern was also (Table 5-5). The mean abundances for the observed in 1992 and during the operation- season beginning in late 1992 are not yet al period, although the secondary peak was available because the period of peak abun-later and smaller during the operational dance extends through the change of year. period. October and November densities Analysis of variance indicated that the were lower than usual in 1992 and during average operational abundance was lower the operational period. The average than abundance during the recent preopera-abundance in 1992 and for the three year tional period (Table 5-6). However, there operational period was lower than the were no significant differences in lower 95% confidence limit of the preoper- abundance among stations. Annual and ational mean at all three stations (Table seasonal (monthly) differences. were 5-5). Average operational abundances were statistically significant (Table 5-6), significantly lower than recent preopera-tional abundances (1986-1989) at all sta-tions (Table 5-6). 5.3.1.3 Ichthyoolankton Entrainment The greatest potential effect of the Ro110th operation of Seabrook Station on ich-thyoplankton is expected to be mortality Pollock larvae also exhibited a fall- of fish eggs and larvae entrained by the . winter pattern of occurrence, but it was cooling water system. Seabrook's circu-generally briefer than that of herring lating water system was in operation 862 larvae. Relatively large densities of of the 884 days during the August 1990-pollock larvae were collected during both December 1992 operational period. The the preoperational and operational periods average daily flow rate ranged from 5-25
l FIS!! 602,000 m3 (159 million gallons) in October in 1980. The increase in CPUE in 1992 was 1992 to 2,240,000 ini (593 million gallons) primarily due to an increase in the catch in June and July 1992. Entrainment of spiny dogfish, Atlantic herring, and samples were collected on 69 sampling alewife. During 1992, Atlantic herring l dates during the operational period, was the dominant species followed by spiny ] primarily during December-September, dogfish, Atlantic mackerel, alewife, and I pollock (Table 5-8). CPUE of these Twelve taxa of fish eggs and 24 taxa of species all increased between 1991 and fish larvae were recorded from entrainment 1992 with the exception of pollock, which l samples in 1992. Total entrainment was was relatively constant. estimated for both eggs and larvae for q January-August and for December 1992 on Changes in the composition of the the basis of observed densities in pelagic fish community between the pre-entrainment samples and the total cooling operational and operational periods were water flow (Table 5-7). Atlantic mackerel examined by comparing the geometric mean and cunner /yellowtail flounder eggs were CPUE of the dominant species. Five entrained in the greatest numbers during species ( Atlantic herring, blueback her-those months, and the greatest numbers of ring, Atlantic whiting, pollock, and larvae entrained were rock gunnel, At- Atlantic mackerel) accounted for approxi-lantic seasnail, grubby, and American sand mately 79% of the average preoperational lance. These were the same taxa of eggs gill net catch . (Table 5-8). Atlantic j and larvoo that were dominant in entrain- herring was again dominant during the j ment samples during 1991 (NAI 1992). The operational period, followed by spiny dog-estimated numbers entrained were somewhat fish, Atlantic mackerel, pollock and greater in 1991 than in 1992 (Figure 5-6). alewife. The primary difference in These estimates can be considered to species composition between the pre-represent total losses due to entrainment operational and operational periods was (assuming the worst case of 100% mortality the increased CPUE of spiny d sgfish. The. of entrained ichthyoplankton). CPUE of spiny dogfish was aximately 13 times higher during th sperational period (0.40 fish /24 hours) than the 5.3.2 Mult Fish preoperational period (0.03 fish /24 hours). 5.3.2.1 Communities Inter-Annual Patterns in the Pelaric Soatial Patterns in the Polarie Fish Fish Community Community l Catch per unit effort (CPUE) for gill CPUE at gill net stations G1, G2,.and l nets, (all stations combined) increased G3 showed similar fluctuations among years to 10 fish per net in 1992 (Figure 5-7), (Figure 5-7). CPUE at any single station This CPUE was the highest recorded since was not consistently larger than any other q the record CPUE of 29 fish per 24-hour set station. Trends in species composition 4 5-26 l
l l l l f*ISil l l TABLE 5-7. MONTHLT ESTIMATED NUXIERS OF FISH E005 AND LARYAI ENTRAINED (x104 ST THE CCOLING WATER SYSTEN AT SEAAR00K STAfl0N , DURING JANUART THROUCE AUGUST AND DECEXBER 1992. SEABROOK OftRATIONAL REPORT, 1992. l TAXON JAN FIl MAR Al!! MAT JUN JUL AUC DEC TCrTAL ETS ATLAhTIC MACKEREL 0.0 0.0 0.0 0.2 170.5 283.4 2.1 0.0 0.0 456.3 CUNNER /YELLONTAIL FLOUNDER 0.0 0.0 0.0 0.1 18.2 84,9 81.3 14.2 0.0 198.6 AME21CAN PLA!CE 0.0 0.0 0.0 32.5 14.9 4.1 0.8 0.0 0.0 52.3 BAK2/70URSEARD ROCKLING 0.0 0.0 0.0 0.3 16.8 13.6 8.3 11.7 0.0 50.6 ATLANTIC C00/ WITCH FLOUNDER 0.0 0.0 0.0 1.2 4.2 20.5 10.0 1.2 0.0 37.1 UINDOWANE 0.0 0.0 0.0 0.0 8.6 8.7 2.6 2.6 0.0 22.5 ATLAVI!C CCO 0.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.7 1.8 ATLANTIC MEh1ADEN 0.0 0.0 0.0 0.0 0.0 1.4 0.0 0.0 0.0 1.4 70VR3EARD ROCXLING 0.0 0.0 0.0 0.0 0.2 0.2 0.4 0.0 0.0 0.8 ATLAhilC C00/RA000CK 0.0 0.0 0.6 0.0 0.0 0.0 0.0 0.0 0.0 0.6 POLLOCK 0.1 0.0 0.0 0.0 0.0 0,0 0.0 0.0 0.2 0.4 ATLANTIC WHITING 0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0.0 0.1 TCftAL 0.3 0.0 0.6 31.2 233.4 417.0 105.5 29.6 1.9 822.6 LAEYM POCK GUNNEL 0.3 10.5 30.0 4.3 0.2 0.0 0.0 0.0 0.0 45.3 ATLANTIC SEASNA!L 0.0 0.0 0.0 2.9 11.3 14.9 2.3 0.1 0.0 31.5 GRUBBY 0.0 0.6 11.5 4.3 2.2 0.3 0.0 0.0 0.0 18.9 AMERICAN SAND LANCE 0.9 6.7 6.1 3.2 1.1 0.1 0.0 0.0 0.0 18.1
% INTER ELOUNDER 0.0 0.0 0.0 0.0 0.3 5.9 0.0 0.0 0.0 6.2 ATLANTIC HERRING 0.0 0.0 0.0 0.3 0.0 0.0 0.0 0.0 4.6 4.9 GULTSHAILFISH 0.5 0.6 0.4 0.2 0.1 0.1 0.0 0.0 0.0 1.9 UNIDEhTIFIED 0.0 0.1 0,1 0.6 0.2 0.3 0.1 0.0 0.0 1.4 RADIATED SHANNY 0.0 0.0 0.0 0.0 0.7 0.1 0.2 0.0 0.0 1.1 AMERICAN PLAICE 0.0 0.0 0.0 0.1 0.0 0.7 0.0 0.0 0.0 0.8 LO!GORN SCULPIN 0.1 0.2 0.2 0.1 0.0 0.0 0.0 0.0 0.0 0.6 Sil0RTHORN SCULPIN 0.0 0.5 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.6 ATLANTIC C00 0.0 0.0 0.0 0.0 0.0 0.4 0.0 0.0 0.0 0.4 R DEISH 0.0 0.0 0.3 0.1 0.0 0.0 0.0 0.0 0.0 0.4 HOUSTACRE SCULPIN 0.0 0.1 0.1 0.2 0.0 0.0 0.0 0.0 0.0 0.3 1 ALLICATORf!SB 0.0 0.0 0.0 0.2 0.1 0.0 0.0 0.0 0.0 0.2 YELLOWIAll FLOUNDER 0.0 0.0 0.0 0.0 0.1 0.1 0.0 0.0 0.0 0.1 HADOOCK 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0.1 WIND 0? PANE 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.1 POLLCCI 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 UNIDENTIFIED SCULPIN 0.0 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.1 70UtBEARD R0'KLING 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.1 LUMPFISH 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.1 CAlNBCW SMELT 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 TOTAL 1.9 19.2 48.8 16.3 16.3 22.9 2.8 0.2 4.7 133.1 5-27
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4 TABLE 5-8. GE0 METRIC HEAN CATCl! PER UNIT EFFORT (NUMBER PER 24-l{00R SET, SURFACE AND BOTT0H) FOR ABUNDANT SPECIES COLLECTED IN GILL NETS AT STATIONS G1, G2 AND G3 COMBINED FOR TIIE PREOPERATIONAL PERIOD WITil 95% CONFIDENCE LIMITS, AND 1991, 1992 AND OPERATIONAL HEAN. SEABROOK OPERATIONAL REPORT, 1992.
, PREOPERATIONAI. PERIOD OPERATIONAL PERIOD SPECIES LCL MEAN b UCL 1991 1992 NEAN' Atlantic herring 0.51 0.83 1.21 0.39 0.50 0.44 Atlantic whiting 0.09 0.23 0.39 0.03 0.16 0.10 Blueback horring 0.15 0.23 0.31 0.13 0.07 0.10 Pollock 0.16 0.22 0.27 0.20 0.19 0.20 Atlantic mackerel 0.15 0.20 0.26 0.12 0.33 0.23 Alewife 0.07 0.10 0.13 0.08 0.21 0.15 htlantic menhaden 0.05 0.07 0.10 0.03 0.09 0.06 dake species
- 0.04 0.06 0.08 0.00 0.06 0.03 Rainbow smelt 0.04 0.05 0.07 0.02 0.07 0.04 Atlantic cod 0.04 0.05 0.07 0.00 0.02 0.01 Spiny dogfish 0.01 0.03 0.04 0.14 0,40 0.27 Other species 0.08 0.10 0.13 0.16 0.20 0.18
" Includes red, white and spotted hake l Dfean of annual means, 1976-1989 l 'Hean of annual means, 1991-1992 5-29
FISli ~~~~ l and CPUE were also similar among stations 1991; however, CPUE of spiny. dogfish (Table 5-9). Tho' primary difforences in increased greatly. In 1992, spiny dogfish species composition and CPUE between the CPUE increased to where it was the most preoperational and operational periods at abundant species. Atlantic herring CPUE all stations were the increase in demi- remained constant between 1991 and 1992. nance of spiny dogfish and the decrease l in dominance of Atlantic herring. Inter-Annual Patterns in the Demersal Atlantic herring dominated the catch Fish Community during the preoperational period at Station G1, located approximately 2 km Otter trawl CPUE (fish per ten-minute south of the discharge (Table 5-9). Dur- tow) for all stations and species combined ing 1991, the first ful1 operational year, during the preoperational period peaked Atlantic herring was again dominant and in 1981 at 95 fish / tow (Figure 5-8). CPUE species composition was similar to the increased to a second peak of 61 fish / tow preoperational period. Spiny dogfish CPUE in 1989, but then decreased to the current increased greatly in 1992 to the highest record low of 24 fish / tow in 1992. During recorded levels. 1992, longhorn sculpin was the dominant species followed by winter flounder, skato Station G2, located approximately 250 species, hake species, yellowtail floun-m southwest from the dischargo, showed a der, and windowpane (Table 5-10). CPUE similar pattern in species composition and of all historically abundant species CPUE as Station 01. Atlantic herring was except haddock decreased between 1991 and the dominant species in the preoperational 1992, period followed by pollock and blueback herring (Table 5-9). In 1991, the Changes in the composition of the dominance of Atlantic herring decreased demersal fish community between the as spiny dogfish and bluefish became a preoperational and operational periods larger part of the total catch. In 1992, were examined by comparing the geometric CPUE of Atlantic herring rebounded, but mean CPUE of the dominant species. During still remained below preoperational the preoperational period, five species levels. CPUE of spiny dogfish in 1992 (yellowtail flounder, longhorn sculpin, decreased but was above preoperational hake species, winter flounder, and skate levels. species) accounted for approximately 74% of the average preoperational otter trawl Station G3, located approximately 2.5 catch (Table 5-10). During the operation-km north of the discharge area, showed al period, CPUE of all these species de- ] similar patterns in CPUE and species creased (except skate species) and their composition as Stations G1 and G2 (Table relative ranking of abundance changed. , 5-9). Atlantic herring was the dominant Winter flounder was the dominant species ( during the preoperational period followed in the operational . period followed by i by Atlantic whiting and blueback herring. longhorn sculpin, yellowtail flounder, Atlant.ic herring was dominant again in skate species and hake species. The 5-30
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76 77 74 79 80 il 31 83 le 25 l6 87 84 09 90 91 91 YEAR Figure 5-8. Annual total catch per unit effon (mean number per 10 minute tow) in otter trawls by station and mean of stations, 1976-1992. Seabrook Operational Report,1992. TABLE 5-10. GE0HETRIC HEAN CATCH PER UNIT EFFORT (NUMBER PER TEN-HINUTE TOW) FOR ABUNDANT SPECIES COLLECTED IN OTTER TRAWLS AT STATIONS T1, T2 AND T3 _ COMBINED FOR THE PREOPERATIONAL PERIOD WITH 957. CONFIDENCE LIMITS, 1991, 1992, AND OPERATIONAL HEAN. SEABROOK OPERATIONAL REPORT, 1992. I PREOPERATIONAL PERIOD
- OPERATIONAL PERIOD
- b UCL 1991 1992 NEAN*
SPECIES LCL HEAN Yellowtail flounder 7.38 9.11 11.19 3.38 0.84 2.11 Longhorn sculpin 2.62 3.76 5.24 2.76 2.10 2.43 Hake species d 2.58 3.21 3.94 2.11 0.93 1.52 Winter flounder 2.43 3.20 4.14 3.79 2.04 2.92 Rainbow smelt 0.73 1.06 1.45 0.90 0.40 0.65 Atlantic cod 1.15 1,72 2.45 0.39 0.14 0.27 Skate species
- 1.25 1.75 2.36 2.58 1.10 1.84 Atlantic whiting 0.43 0.67 0.95 0.52 0.42 0.47 Ocean peut 0.64 0.80 0.98 0.32 0.23 0.28 Pollock 0.20 0.35 0.51 0.80 0.28 0.54 Windowpane 0.90 1.27 1.70 1,49 0.72 1.11 Haddock 0.09 0.21 0.35 0.00 0.04 0.02 Other species 1.17 1.39 1.64 1.60 0.81 1.21
*In most years, sampling was curtailed at Station T2 during September and October due to presence of lobster gear, b Moan of annual means, 1976-1989 )
*Mean of annual means, 1991-1992 Includes red, white and spotted hake
' Includes big, little, and thorny skates 5-32
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FIS!! l primary difference in the species compo- Species composition during the pre-cition of the demersal fish community operational period at Station T1, located between the preoperational and operational approximately 4 km south of the discharge periods was the decrease in CPUE of area, was dominated by yellowtail floun-yellowtail flounder, der, hako species, and longhorn sculpin (Table 5-11). Yellowtail flounder was the dominant species during the operational Soatial Patterns in the Demersal Fish period although CPUE greatly declined. Community Winter flounder and skate species were the next most abundant species. CPUE of the Species composition, as measured by majority of abundant species declined CPUE, was different among otter trawl during the operational period, with stations (Table 5-11). During both the yellowtail flounder showing the greatest preoperational and operational periods, proportional decrease, yellowtail flounder was the dominant opecies at Stations T1, while winter Winter flounder, yellowtail flounder and flounder was dominant at Station T2. rainbow smelt were the dominant species AtStation T3, yellowtail flounder was during the preoperational period at dominant in the preoperational period, re- Station T2, located approximately 1 km placed by longhorn sculpin during the south of the discharge (Table 5-11), operational period. The differences in During the operational period, winter habitat among the stations probably flounder were again dominant followed by account for the differences in species rainbow smelt and hake species. CPUE of composition. Station T2 is located in all abundant species decreased between the shallower water with a bottom occasionally preoperational and operational periods, covered with drif t algae, while Stations with the exception of pollock, and spiny T1 and T3 are located in deeper water with dogfish, which were relatively stable, sandy bottoms. Among the dominant species, yellowtail flounder CPUE had the largest proportional Mean annual CPUE in 1992 was similar at decrease. the farfield stations (T1 and T3) while CPUE at the shallower nearfield station Species composition at Station T3, (T2) was much lower (Figure 5-8). Trawl located approximately 4 km north of the samples are not regularly collected at discharge area was dominated by yellowtail Station T2 duting August through October, flounder, longhorn sculpin and hake a period when catches were high at the species during the preoperational period. other stations (NAI 1993). Therefore, the Species composition changed during the low annual catch at Station T2 compared ' operational period, with longhorn sculpin j to the lack of sampling during months when dominant followed by winter flounder and catches were high at the other stations skate species. CPUE of all abundant l (NAI 1993), species was lower during the operationa, period with the exception of pollock and winter flounder, which increased slightly. l 5-33 1 j
TAELE 5-11. GE0fETRIC MEAN CATCH FER UNIT EEFORT (NUMEER FER 10 MIN'JiE TRAWL) BY STATION FOR AELTNDAhT SPECIES COLLECTED IN CITER TRAWLS Dl!RI)G THE PREOPERATIONAL PERIOD WITH 95: CONEIDENCE LIMITS. AND 1991. 1992 AND OPEEATIONAL F AN. SEAER00L OPERATIONAL EEPORT. 1992. STATION Tl STATION T2 STATION T3 b b OPERATI0pi PERIODb FREOPERATIONAL PERIOD
- OPERATIONAL PERIOD PREOPERATIONAL PERIOD
- OPERATIONAL PERIOD PREOPERATIONAL PERIOD
- SPECIES LCL MEAN llCL 1991 1992 MEAM LCL MEAN lEL 1991 1992 MEAN LCL MEAN 11CL 1991 1992 MEAN Tellowtail flounder 16.19 20.04 24.75 7.51 1.95 4.73 2.12 2.85 3.75 0.71 0.15 0.43 7.72 10.12 13.17 3.56 0.67 2.12 T Hake species 3.52 4.46 5.58 2.91 1.45 2.18 1.22 1.61 2.06 1.07 0.34 0.71 2.99 3.84 4.87 2.36 1.01 1.69 y longborn sculpin 3.02 4.26 5.87 3.08 2.39 2.74 0.69 1.05 1.48 0.46 0.22 0.34 5.11 7.60 11.12 6.01 4.92 5.47 Winter flounder 2.03 2.84 3.87 4.75 2.30 3.53 3.94 5.63 7.89 3.36 1.15 2.26 1.63 2.12 2.71 3.29 2.69 2.99-Windovpane 1.22 1.84 2.63' 2.73 1.55 2.14 0.69 0.95 1.26 0.89 0.47 0.68 0.67 1.03 1.47 1.05 0.32 0.69 Atlantic cod 1.23 1.83 2.61 0.26 0.22 0.24 0.41 0.67 0.98 0.14 0.03 0.09 1.83 2.94 4.50 0.76 0.17 0.47 Skate species 0.91 1.61 2.57 4.70 1.91 3.31 0.36 0.51 0.67 0.18 0.19 0.19 2.95 3.71 4.61 4.15 1.37 2.76 Atlantic whiting 0.58 0.96 1.44 0.55 0.52 0.54 0.10 0.18 0.27 0.11 0.00 0.06 0.59 0.91 1.31 0.88 0.76 0.82 Rainbow smelt 0.65 0.95 1.31 0.55 0.40 0.48 1.25 1.81 2.51 1.56 0.41 0.99 0.42 0.69 1.01 0.87 0.39 0.63 Ocean pout 0.49 0.63 0.77 0.21 0.11 0.16 0.41 0.55 0.71 0.40 0.21 0.31 0.97 1.26 1.60 0.37 0.39 0.38 Pollock 0.18 0.30 0.44 1.36 0.40 0.88 0.31 0.61 0.98 0.86 0.39 0.63 0.11 0.19 0.28 0.34 0.10 0.22 Haddock 0.05 0.16 0.28 0.00 0.01 0.01 ( 0.01 0.03 0.06 0.00 0.00 0.00 0.19 0.47 0.82 0.00 0.10 0.05 Spiny dogfish < 0.01 0.01 0.01 0.04 0.00 0.02 0.00 0.00 0.00 0.02 0.00 0.01 < 0.01 0.01 0.02 0.00 0.00 0.00 All other species 1.29 1.62 2.00 1.95 1.47 1.71 1.12 1.43 1.79 1.78 0.42 1.10 0.92 1.15 1.41 1.18 0.61 0.90
*Mean of annual means. 1976-1989 b
Mean of annual means. 1991-1992
-. _.- - - - - -- _. -. . _ _ _ _ . - .- - - . . _ - . = - . -
FISil Anong the abundant species, yellowtail Hampton liarbor, were lower and more stable flounder CPUE had the largest percentage among years than the other two stations. decrease. (Figure 5-9). In 1991 and 1992, mean CPUE was highest at Station Si followed by Sta-tion S3 and S2 (Figure 5-9). The high Inter-annual Patterns in the Estuarine annual variability was due to large Fish Comalunity fluctuations in the CPUE of the dominant species, Atlantic silverside. Average CPUE for all seine stations combined within the llampton-Seabrook Species composition, as measured by estuary ranged from 41 to 362 fish / haul CPUE, was dif ferent among seine stations and averaged 43 fish / haul in 1992 (Figure (Table 5-13). Atlantic silverside fol-5-9). Seine CPUE was generally lower lowed by winter flounder were the dominant during the period 1982 through 1992 (41- species at Station 53 during both the 114 fish / haul) than 1975 through 1981 (200 preoperational and operational periods.
- to 362 fjsh/ haul), primarily dun to At Station S2, Atlantic silverside and decreases in Atlantic silverside abundance Fundulus species were dominant during the (NAI 1992). Rainbow smelt abundance also preoperational period. Atlanti: silver-
- strongly influenced the overall CPUE. side was also dominant during tne opera-During peak years of CPUE, such as 1976, tional period but Atlantic harcing ranked 1979 and 1990, rainbow smelt CPUE was second in abundance. No Fundulus species above average (NAI 1992), were collected at Station S2 during the operational period. At Station S1, Atlan-During the preoperational period At- tic silverside and Fundulus species were lantic silverside was the most abundant the two most abundant fishes during both fish followed by winter flounder and the preoperational and operational peri-ninospine stickleback (Table 5-12), ods.
Atlantic silverside and winter flounder i were also the dominant fishes during the operational period with Fundulus species 5.3.2.2 Selectcil_Soccles ranking third in abundance. Polaric Soecies SpglgLhtterns in the Estuarine Fish Atlantic lierrine Community Atlantic herring are seasonal migrants Mean annual CPUE during the preopera to New England waters during the summer tional period was highly variable, and early f all (Whittatch 1982). Spawning Station S3 (near the mouth of the estuary) occurs in the Gulf of Haine during late had the highest inter-annual variability, August through October and adults migrate showing dramatic increases in CPUE in to southern overwintering grounds shortly 1976, 1979, 1981, and 1990 (Figure 5-9). after spawning (Whitlatch 1982; NOAA Catches at Station S1, most distant f rom 1992). Young-of-the year Atlantic herring 5-35
a- ----- s=== si sumson $2
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75 76 77 78 79 80 $1 82 83 54 IS ' .b 86 #7 48 39 90 91 92 YEAR e p , ,,,,, ,,,pi. ,,g.s,a m 19si 6 s4= n. Apr0 esaissh h Figure 5-9. Annual total catch per unit effort (mean number per haul) in beach seines by station and mean of stations. 1976-1992. Seabrook Operational Report,1992. TAB LE 5 - 12. GE0HETRIC HEAN CATCH PER UNIT EFFORT (NUMBER PER HAUL) FOR THE TEN HOST ABUNDANT SPECIES COLLECTED IN BEACH SEINES AT STATIONS S1, S2 AND S3 COMBINED FOR THE PREOPERATIONAL PERIOD WITH 95% CONFIDENCE LIMITS, AND 1991, 1992 AND OPERATIONAL HEAN. SEABROOK OPERATIONAL REPORT, 1992. PREOPERATIONAL PERIOD OPERATIONAL PERIOD SPECIES LCL HEAN" UCL 1991 1992 HEANb Atlantic silverside 5.16 7.56 10.90 5.57 2.78 4.18 Tundulus species 0.49 0.73 0.99 0.57 0.04 0.31 Pollock 0.04 0.20 0.39 0.14 0.07 0.11 Alewife 0.02 0.08 0.14 0.02 0.01 0.02 Rainbow smelt 0.20 0.31 0.43 0.21 0.08 0.15 American sand lance 0.06 0.14 0.23 0.12 0.10 0.11 Atlantic herring 0.09 0.16 0.22 0.20 0.07 0.14 Ninespine stickleback 0.39 0.75 1.21 0.25 0.32 0.29 Winter flounder 1.15 1.49 1.89 0.70 0.37 0.54 Plueback herring 0.03 0.21 0.41 0.16 0.00 0.08 Other species 0.81 1.08 1.40 0.80 0.23 0.52
- mean of annual means, 1976-1989 -i b meen of annual means, 1991-1992
" includes mummichogs and striped killifish 5-36
TABLE 5-13. CEOMETRIO EAN CATCH PER UNIT EFFORT (NUMBER FER HAUL) BT STATION FOR TE TEN 10ST HOST ABUNDHI SPECIES COLLECTED IN BEACH SEIES FOR TEE PREFERATIONAL PERIOD WITH 95I CONFIDENCE LIMITS. AND 1991,1992 AND OPERATIONE EAN. SEAER00K OPERATIONAL REPORT 1992. STATION S1 STATION S2 STATION S3 b b OPERATIONAL PERIOD b PREOPERATIONAL PERI @
- OPERATIONAL PERIOD PREOPERATIONAL PERIOD
- OPERATIONAL PERIOD PREOPERATIONAL PERI W "
SPECIES IfL EAN UCL 1991 1992 MEAN LCL MEAN UCL 1991 1992 EAN IfL EAN UCL 1991 1992 EAN . American sand lance 0.01 0.10 0.19 0.36 0.34 0.35 0.01 0.22 0.48 0.00 0.00 0.00 0.04 0.12 0.20 0.04 0.00 0.02 Atlantic silverside 5.42 7.65 10.66 7.04 2.76 4.90 5.34 7.54 10.50 3.44 2.12 2.78 4.42 7.49 12.30 6.% 3.59 5.27 Y Blueback herring 0.06 0.28 0.53 0.47 0.00 0.24 0.01 0.13 0.26 0.00 0.00 0.00 0.02 0.23 0.49 0.07 0.00 0.04 d Alevife 0.01 0.08 0.15 0.07 0.04. 0.06 < 0.01 0.09 0.18 0.00 0.00 0.00 0.02 0.07 0.12 0.00 0.00 0.00 Atlantic berring < 0.01 0.10 0.22 0.18 0.00 0.09 0.09 0.25 0.43 0.09 0.22 0.16 0.06 0.13 0.20 0.33 0.00 0.17 Fundulus sp. 0.84 1.16 1.54 2.84 0.13 1.48 0.68 1.27 2.07 0.00 0.00 0.00 0.02 0.05 0.07 0.00 0.00 0.00 Pollock 0.01 0.11 0.22 0.12 0.00 0.06 0.02 0.16 0.31 0.04 0.00 0.02 0.06 0.36 0.73 0.20 0.21 0.24 Ninespine stickleback 0.42 0.77 1.21 0.70 0.30 0.50 0.26 0.76 1.45 0.04 0.12 0.08 0.31 0.73 1.28 0.09 0.57 0.33 Rainbow smelt 0.03 0.13 0.24 0.12 0.12 0.12 0.% 0.16 0.26 0.21 0.09 0.15 0.36 0.73 1.1* 0.37 0.04 0.18 Winter flounder 0.69 0.a7 1.29 0.85 0.00 0.43 0.66 1.02 1.44 0.17 0.12 0.15 1.97 2.92 e.17 1.26 1.31 1.29 All other species 0.55 0.86 1.24 0.33 0.09 0.21 0.79 1.03 1.31 0.45 0.14 0.30 0.89 1.31 s.01 2.04 0.51 1.28
*Mean of annual means. 1976-1984, 1987-1989 bMean of annual means, 1991-1992
l l FISH l (spawned the previous fall) appear in 5-10). This pattern was repeated during coastal waters b'y summer (Bigelow and the operational period, when CPUE was Schroeder 1953). Atlantic herring monthly highest in the spring through fall and few mean CPUE during the preoperational period pollock were captured during the winter. was highest during the spring and fall In 1992, average monthly catches were (Figure 5-10). In 1992 and during the lower than the preoperational mean in May two-year operational period, the spring and November, and higher than average in peak in CPUE occurred one month later and August. The average annual CPUE in 1992 fall abundances were greatly reduced in was similar to that reported in 1991 and comparison to the preoperational period. during the preoperational period (Table 5-8). There were no significant differ-The average annual catch increased in ences in CPUE during the selected months 1992 from the 1991 mean, but was still between the preoperational and operational well below the preoperational average periods or among stations (Table 5-14). (Table 5-8). The average CPUE during the CPUE differed significantly among years selected months was significantly lower and months. Pollock biomass indices for during the operational period and there the Gulf of Maine have declined sharply were no significant differences among since the mid-1980s and have remained stations (Table 5-14). Significant relatively low since 1984 (NOAA 1992). differences were noted among years and -_ months. Atlantic herring Age 2+ stock biomass in the Gulf of Maine has increased Atlantic Mackerel significantly si.nce 1981 to present record levels (NOAA 1992). The decrease in At- The northern population of Atlantic latic herring CPUE during the operational mackerel spawns in the spring and early w riod in the study area contrasts with summer (Bigelow and Schroeder 1953) the recent increase in Atlantic herring primarily in the Gulf of St. Lawrence biomass in the Gulf of Maine. (NOAA 1992). Adult Atlantic mackerel overwinter on the outer continental shelf between Cape Sable'and Cape Hatteras and Pollock typically first appear in the Gulf of Maine in May (Bigelow and Schroeder 1953; Pollock spawn in the Gulf of Maine in NOAA 1992). Atlantic mackerel monthly the late fall and early winter. Small mean CPUE in gill nets was greatest in pollock of ten appear in inshore waters in June through November of the preopera-the spring and move to deeper waters in tional period (Figure 5-10). During the the summer as water temperatures increase. operational period, Atlantic mackerel were These pollock then return to inshore present from June through November with waters in the f all as water temperatures the highest catches in October. In 1992, , decrease (Bigelow and Schroeder 1953). higher than average catches occurred in Monthly mean CPUE of pollock was typically June and August through November, while highest during the late spring and late catches were lower than average in July. fall, and lowest during the winter (Figure 5-38
l l l l Atlantic herring 1.2 - , Prnoperanonal l
.......... p aa g l g --o-- tw2
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~
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4 T T 4 4 I i 4 4 4 I 4 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH Pollock i.2 - Pr.opme.a
.......... Op.6.a w --o-- inz a 0.8 -
c. U 0.6 - 0.4 - ,CL [*, ~ D
*7 -j JAN FEB MAR APR MAY NN JUL AUG SEP OCT NOV DEC MONTH Atlantic mackerel 1.2 - Pyuanal 1.0 -
Opmdand ga --o-- 1992 a 0. 8 - D. V 0.6 - O'" ~
/ s *:.A .=,
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0.2 - f.***
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N ,- -- 3. L 0.0 y y , y y y , , , 3 _ JAN FEB MAR APR MAY JUN JLL AUG $EP OCT NOV Dr4 MONTH Figure 5-10. Log (x+1) catch per unit effort (number per 24-hr. set) for Atl.mtle herring, pollock and Atlantic mackerel; monthly means and 95% conf.dence intervals over all preoperational years (1976-1989) and monthly means fcr the operational r years (1991 1992) and 1992 averaged over gill net Statioris Gl. U2 and G3. Scabrook Operational Report,1992. 5-39
W TABLE 5-14. RESULTS OF J 4 LYSIS OF VARIANCE COMPARING ABUNDANCES OF SELECTED SPECIES OF PELAGIC FISH AT ALL TLL NET STATIONS DURING PREOPERATIONAL AND OPERATIONAL PERIODS. SEABROOK OPERATIONAL REPORT, 1992. MULTIPLE COMPARISONS
- SPECIES SOURCE OF (Ranked in (MONTHS USED) VARIATION
- df SS N decreasing order) !
Atlantic herring
- Preop-Op _
1 1.54 15.39*** Preop >Op (Jan-May, Sep-Dec) Year (Preop-Op) 15 2.38 23.80*** Month (Year) 135 0.55 5.55*** Station 2 0.01 0.13 NS Preop-Op X Station 2 0.01 0.12 NS Error 486 y Pollock" Preop-Op 1 0.02 0.51 NS
$ (Apr-Dec) Year (Preop-Op) 15 2.77 4.19***
Month (Year) 136 12.23 2.04*** Station 2 0.20 2.25 NS Preop-Op X Station 2 <0.01 0.05 NS , Error 491 Atlantic mackerel d Preop-Op 1 0.06 1.75 NS (Jun-Nov) Year (Preop-Op) 14 2.98 5.91*** Month (Year) 80 10.63 3.69*** Station 2 0.28 3.83* G3 G2 G1 Preop-Op X Station 2 0.13 1.85 NS Error- 314
- Preop-Op = Preoperational period vs. operational. period Year (Preop-Op) = Year nested within preoperational and operational perciods Month (Year) = Month nested within year b NS = not significant (p>0.05)
* = significant (0.052p>0.001)
** = highly significant (0.012p>0.001)
*** = very highly significant (ps0.001)
*1990 classified.preoperational 1MO catch deleted
" Underlining indicates no significant difference in least square means (a S 0.05)
- FISil -
The average annual catch in 1992 'in- Atlantic cod CPUE for the selected months creased from low I'evels in 1991 to a value was significantly lower during the that was greater than the preoperational operational period at all stations, end mean (Table 5-8). There were no signifi- this decrease was greater at Station T2 cant differences in average CPUE of (nearfield) compared to the farfield Atlantic mackerel during the selected stations (Table 5-15). The decrease in months between the preoperational and CPUE during the operational period at the operational periods (Table 5-14). nearfield station was pronounced during
' Significant dif ferences were noted among every month sampled except June (Figure years and months. Estimates of stock 5-11). Significant differences among biomass of Age 1 and older fish betwoon years and months were noted.
Labrador and North Carolina have increased steadily since 1981 and are presently at Both commercial landings and the esti-record levels-(NOAA 1992), mated spring spawning stock biomass of Atlantic cod in the Gulf of Maine in-CPUE of Atlantic mackerel during the creased between 1986 and 1991 due to the selected months was significantly greater strong 1987 year _ class (NOAA 1992). at Station G3 located north of the ir.take. However, in 1992 the spring spawning stock The Proop-Op X Station interactica term biomass decreased substantially, which is was not significant, Indicating a consis- reflected in the low CPUE of Atlantic cod ; tent relationship among statior.s regard- in the study area. Despite the recent { 1ess of operational status. increases in commercial landings in the
]
Gulf of Maine, the Atlantic cod stock is considered overexploited (NOAA 1992). Demersal Soecies itlantic cod 1[nksa Atlantic cod migrate offshore in the Red hake spawn from May through November summer as water temperatures increase and in the southwest part of Georges Bank i reappear in inshore waters in the fall as (NOAA 1992) . Overwintering occurs in the l water temperatures decrease (Bigelow and deeper parts of the Gulf of Maine and on l Schroeder 1953). Monthly mean Atlantic the continental shelf and slope of south cod ( PW. vas typically highest in the and southwest of Georges Bank (NOAA 1992). spring and fall and lowest during the White hake spawn during the winter and summer (Figure 5-11) . Monthly mean CPUE spring although the exact area of spawning in 1992 and during the operational period has not been delineated (NOAA 1992). l was consistently lower than monthly mean Juveniles and adults move into shallower CPUE during the preoperational period. water in the spring and summer and dis-perse to deeper waters in the fall. Ifake The average annual catch in 1992 species CPUE in the study area was decreased from levels in 1991 at all three composed of red hake, white hake and stations (Table 5-11). The average spotted hake. Monthly CPUE of hake spe-5-41
Station T1 u- %a
%.u.a
--o-- in2 td 1 0-6 8
a 0.3 - -
/N _N
. N I T _/
!.!.1 55.. .,., $ - ,
i- ~;'J i ~ E' h .,'ii'.<...'.1 a i 7---" - 4..... . i i . . JAN IT.B MAR APR MAY JUN JUL AUG SEP OCr NOV DEC MONTH Station T2 u- %e.a w .a
--o__ im d 1.0 -
c. U . 8 -3 0.5 - p
----*-/M *
- T * - !.3 _
JAN FEB MAR APR MAY JUN PJL AUG SEP OCT NOV DEC MONTH Station T3 IJ "
%d.a
.......... p. g
--4-- 1992 g 1.0 - .
a. v 8 a 0.s - y
/
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' p g ................p-0.0 , , , *'i == .
JAN n.B MAR APR MAY JUN R AUG SEP OCr NOV DEC MONTH Figun: 5 11. Log (x+1) catch per unit effon (mean number per ten minute tow) for Atlantic ) cod; mon hly means and 95% confidence intervals over all preoperational years (1976-1989) and monthly means for the operatianal years (1991-1992) and 1992 at otter trawl Staions TI, T2 and T3. Seabrook Operational Repon,1992. 5-42
s l TABLE 5-15. RESULTS OF ANALYSIS OF VARIANCE COMPARING ABUNDANCES OF SE ECTED SPECIES OF DEMERSAL FISH AT ALL TRAWL STATIONS DURING PREOPERATIONAL AND OPERAYIONAL PERICOS. SEABROOK OPERATIONAL REPORT,1992. . SPECIES IfULTIPE COMPARISONS' (HONTHS USED) SOURCE OF VARIATION
- df $$ @ (Ranked in decreasing order)
Atlantic cod
- Preep-op 1 10.65 179.07***
(Jan-Jul Nov-Dec) Year (Preop-Op) 15 22.27 24.97*** Month (Year) 136 24.15 2.99*** Station 2 4.22. 35.48*** Preop-Op X Station 2 0.97 8.11*** T3 Pro. T1 Pre. T2 Pre. T3 Op, T1 Op, T2 Op Error 465 Eakes d Proop-Op 1 2.87 42.64*** Proop>Op (Jan-Jul, Nov-Dec) Year (Proop-Op) 14 6.79 7.20*** Month (Year) 128 76.39 8.86*** Station 2 1.48 11.01*** T1)T3>T2 (n Proop-Op I Station 2 C.09 0.66 NS g Error 420
" Yellowtail flounder
- Proop-Op 1 30.29 360.09*** Preop >Op (Jan-Jul, Nov-Dec) Year (Proop-Op) 14 14.37 12.20***
Month (Year) 128 15.89 1.48** Station 2 20.23 120.25*** Ti>T3>T2 Proop-Op X Station 2 0.45 2.67 NS Error 420 Winter flounder
- Proop-Op 1 1.91 28.15***
(Jan-Jul, Nov-Dec) Year (Proop-Op) 14 S.31 8.74*** Month (Year) 128 26.69 3.07*** Station 2 1.99 14.66*** Preop-Op X Station 2 1.69 12.43*** T2 Pro T1 Pro, T1 Op. T2 Op, T3 Pro, T3 Op Error 420 (continued) ___ c- - 2
J TABLE 5-15. (Contineed) SPECIES MULTIPLE COMPARISONS' (PioWTits USED) SOURCE OF VA.RIAYION* df SS F* (Ranked in decreasing order) Rainbow smelt
- Proop-Op 1 3.56 31.18*** Preop >Op (Jan-May. Nov-Dec) Year (Preop-Op) 15 12.34 6.64***
Isoeth (Year) 102 $5.12 6.74*** Station 2 0.64 2.60 NS Preop-Op X Station 2 0.59 2.37 NS Error 359
" Station: 71 vs. T2 vs. T3 regardless of year or month; Proop-Op = Preoperational period vs.
y operational period; Year (Preop-Op) = Year nested within preoperational and operational periods, regardless of area; tsanth (Year) = tsanth nested within year, regardless of station; Preop-Op I e A Station = interaction of main effects b NS = not significant (p>0.05)
* = significant (0.052p>0.01)
** = highly significant (0.012p>0.001)
*** = very highly significant (p50.001)
*1990 d
classified preoperational 1990 data deleted
*1990 classified operational
' Underlining indicates no significant difference (o 5 0.05) 'in least squares means.
- - . .a
FISH cies during the preoperational period in- There were significant differences among
. creased steadily from January to a peak stations in CPUE of hake species during during June through October (Figure 5-12). the selected months (Table 5-15). CPUE This pattern was repeated during the was highest at Station T1 followed by operational period when CPUE was highest Stations T3 and T2. Although CPUE was between June and October. Average monthly significantly different among stations, catches in 1992 were lower than average the differences were consistent between in.every month except October, when they the preoperational and operational periods were higher than average. and are likely attributable to differences in habitat.
The annual average catch in 1992 was lower than that reported in 1991 at all three stations (Table 5-11). CPUE of Yellowtall flounder hakes was highest from 1976-1978 and 1981-1982, but steadily declined from 1984- Average yellowtail flounder do not. 1990, then increased slightly in 1991 (NAI undergo any extensive seasonal movements,
- 1992). The average catch in 1992 repre- but move slightly offshore in the summer, sente the lowest to date. As a result, apparently to avoid warm water tempera-average CPUE was significantly lower tures (Bigelow and Schroeder 1953). CPUE during the selected months of the opera- of yellowtail flounder during the preop-tional period. Among-year and among-month erational period was relatively constant differences were significant. among months (Figure 5-12). In 1992 and during the operational period, CPUE was It is difficult to draw comparisons lower and variation in CPUE was larger between the CPUE of hake species in the among months than during the preopera- _.
study area and trends in the Gulf of Maine tional period, because the term " hake species" in this study includes three species, while the Average CPUE of yellowtail flounder in j National Marine Fisheries Service delin- 1992 showed a substantial decrease from ) eates trends for red and white hake 1991 levels to the lowest level recorded l separately. The index of red hake biomass to date (Table 5-11, NAI 1992). Average in the Gulf of Maine and northern Georges yellowtail flounder CPUE during the Bank has increased steadily since 1968, selected months was significantly lower and the stock is presently considered during the operational period (Table 5-underexploited (NOAA 1992). The index of 15). CPUE during the selected months was biomass for white hake in the Gulf of greatest in the preoperational years of ! Maine and Georges Bank has fluctuated 1980 and 1981, and lowest in the opera-without any long-term trends since the tional year of 1992 (Table 5-10, NAI early 1970s (NOAA 1992). The white hake 1992). There were also significant dif-stock in considered fully exploited (NOAA ferences among years, months, and sta-1992). tions. CPUE was greatest at Station T1 followed by Stations T3 and T2. Spatial differences occurred consistently through-5-45 l
I
-1 i
i l I Hake species i 1.4 - Preopermiand
% .a o
--*~~ l'92 . ,'a i.2 - / \
l s i
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JAN FEB MAR APR MAY JUN R1 AUG SEP OCT NOV DEC MONTH Yellowtail flounder 14- Preoperaumal
....... .. Opermied
~~ ~~ l992 1.2 -
y ., 1.0 - -
/% y ---- p g 0.. - . . . ,,
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" i i e i i i i . . . i i JAN FEB MAR APR MAY JUN JUL AUo $EP OCr NOV DEC MONTH Figure 5 12. Log (x+1) catch per unit effort (mean number per 10 minute tow) for hake species and yellowtail flounder; monthly means and 95% confidence intervals over all preoperational years (1976-1989) and monthly means for the operational years l (1991-1992) and 1992 averaged over otter trawl Stations T1, T2 and T3. Seabmok
- Operational Report,1992.
5-46
FISH out the study regardless of operational from May-October was generally higher than status and were probably due to differenc- average at Stations T1 and T3, but average es in habitat. or below average at Station T2. The significant reduction in CPUE at all Averge winter flounder CPUE in 1992 stations between the preoperational and decreased from CPUE in 1991. This operational periods was probably due to decrease was most dramatic at Stations T1 commercial overexploitationof yellowtail and T2, where geometric mean CPUE de-flounder in the Gulf of Maine and Georges creased by more than 50%; CPUE at T3 Bank. The index of yellowtail flounder decreased by 18% (Table 5-11). Winter biomass for the Georges Bank, Southern New flounder CPUE during the selected months England and Cape Cod stocks has fallen was significantly lower during the steadily since the most recent peak la the operational period at Stations T2 (near-early 1980s (NOAA 1992). These stocks are field) and T1 (farfield), but was not presently considered overexploited. significantly different at Station T3, the other farfield station (Table 5-15). The significant Preop-Op X Station interaction Demersal and Estuarine Soecies term indicates that the differences in CPUE between the preoperational and Winter Floundgr operational periods did not occur equally at all stations (Table 5-15). Significant North of Cape Cod, winter flounder differences in CPUE also occurred among typically spawn from February through years and months. April in salinities ranging from full seawater (31-33 ppt) to brackish water (11 The decrease in the CPUE of winter ppt; Bigelow and Schroeder 1953). Young- flounder in the study area in 1991 and of-the-year winter flounder in Waquoit Bay 1992 is in agreement with the trends in on Cape Cod moved less than 100 m during winter flounder abundance in the Gulf of their first summer, primarily in a Maine. The annual spring index of winter downstream direction (Saucerman and Deegan flounder abundance in Massachusetts Bay - 1991). Sexually mature winter flounder Cape Cod Bay was at its lowest recorded exhibited seasonal movements associated value in 1991 and the stock is presently with spawning, where they concentrated in considered overexploited (NOAA 1992). The shoa1 waters during the winter and spring, index of winter flounder abundance for and after spawning, dispersed to deeper 1992 is not yet available; however, water by midsummer (Howe and Coates 1975). preliminary analyses indicate that the Winter flounder monthly mean CPUE in the index increased slightly in 1992, possibly otter trawl during both the preoperational due to management restrictions on commer-and operational periods was highest from cial and recreational fishermen in s May through October (Figure 5-13). Massachusetts (S. Correia, Mass. Div. L Average monthly catches in 1992 were Marine Fish., pers, comm.). generally lower than average from January- l March or April and December, CPUE in 1992 5-47
Station T1 1.6 - p.,pmumel
.......... opmoma
--4-- 1992 1.2 -
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0.2 = / ***"*~- 0~0 p -4 g,_~ / O**'~O l i i T I i i l i i 4 6 JAN l'EB MAR APR MAY AN Et Ath SEP OCr NOV DEC MONTH Station T3 1.6 " Pm>pereumal
.......... Opernumal
.c.. g992 1.2 - p.,,
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p p. - 02- e v g..*...-....*.,o
~ ~ -
r n', T i i I i i 6 4 I 6 i i JAN R8 MAR APR MAY NN Rt AUG SEP OCT NOV DEC MONTH Figure 5-13. Log (x+1) catch per unit effort (mean number per ten minute tow) for winter flounder; , monthly means and 95% confidence intervals over all preoperational years (19761989) and monthly means for the operational years (1991 1992) and 1992 at otter trawl Stations T1, T2 and T3. Seabrook Operational Repon,1992. 5-48 i
I FISH l Haan monthly CPUE of winter flounder in smelt migrate into the water column on a l estuarine seine cdtches (averaged over all flood tJde and remain in deeper water l stations) was greatest in May through during an ebb tido (Ouellet and Dodson 'l October of both the preoperational and 1985). operational periods (Figure 5-14). However,1992 monthly CPUE was lower than Rainbow smelt monthly mean CPUE in the average in almost all months. The average otter trawls was greatest in December and annual CPUE in 1992 for the selected January through March during both the pre-months was substantially lower than CPUE operational and operational periods in 1991 and during the prooperational (Figure 5-15). Monthly catches in 1992 i period at Stations S1 and S2. The 1992 were lower than averagn from January-March CPUE at Station S3 was similar to that and November-December (Figure 5-15). recorded in 1991, but less than half of Average CPUE in 1992 was lower than that the preoperational mean (Table 5-13). At recorded in 1991 and during the preopera-all three stations, CPUE in 1992 was the tional period at all three stations (Table lowest recorded to date (Tablo 5-13. NAI 5-11). Average CPUE during the selected 1992). As a result, winter flounder CPUE months was significantly lower during the was significantly lower during the opera- operational period at all stations (Table tionni pnriod in comparison to the 5-15). The preoperational period includes preoperational porlod (Table 5-16). years with very high catches, including Winter flounder CPUE shows ovidence of a 1988 and 1989 (NAI 1992). long term cycle, with higher CPUE in the preoperational years of 1979 through 1982 Rainbow smolt CPUE in seines was rela-and lower catches from 1987-1992 (NAI tively constant each month during the 1992). Mnan CPUE at Station S3 was preoperational period but was higher in-significantly greater than other stations, August during the operational period possibly due to the higher salinity at (Figure 5-14) . Monthly mean CPUE in 1992 this station, was lower than the preoperational average in all months. The average CPUE in 1992 was similar to that recorded in 1991 and Rainb n.Jmcit during the preoperational period at Station S1. CPUE at Stations S2 and S3 Rainbow smelt are anadromous fish that in 1992 was lower than the average catch spawn in estuaries at the head of the tido in 1991 and during the preoperational in the early spring (Bigelow and Schroeder period (Table 5-13). There were no sig-1953). Af ter spawning, the adults return nificant differences in CPUE between the to high salinity water. The eggs require preoperational and operational periods freshwater or nearly freshwater for (Table 5-16), although significant development. Larval rainbow sm91t main- differences were noted among years and tain position in the estuary through months. Station 53, at the mouth of the vertical migration in combination with the Hampton River estuary, had significantly two layer circulati.on system of northern greater CPUE than the other stations. estuaries. To maintain position, rainbow 5-49
Winter flounder 1.0 - Preopeseunnal
% mmt
~~O~~ I"I 08-d a, 06- .
U . 3 a O s-
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- W 0,.
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......~
o.,3 .r -o---- o- * ,, ,- *..%, 00 , , , , 7 , , , AfH MAY A1N R AtX) SEP 0 07 NOV MONTil Rainbow smelt 0.3 - Preqwammal
%ume
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b 0.2 - . a .* . .
's '
'/
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0.0 T T :r i i s i Alv htAY AN R AIXJ SEP (K.T NOV MONTn Atlantic silverside 2.3 - Pr=>pereuunal
.......... c3.,,,,,,i
--o-- iwa 2.0 -
1':~:.w\
, . . ', ' P' lu t.s - .. ,
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- i 1
i c.7. . i ..t.r..... : i,*_-_s' L .....:.? T I I I I i i i Aft MAY AN M. AtX) 51 7 oCr NOV l l MONTil Figure 5 14. Log (x+1) catch per unit effort (number per haul) for winter flounder, rainbow smelt and Atlantic silverside; monthly means and 95% confidence intervals over all preoperational years (1976 1989) and monthly means for the operational years (1991 1992) and 1992 averaged over beach seine Stations S1, S2 and S3. Seabrook Operational Report,1992, l 5-50 l
TABIE 5-16. RESULTS OF ANALYSIS OF VARIANCE COMPARING ABUNDANCES OF SELECTED SPECIES OF ESTUARINE FISH AT ALL BEACH SEINE STATIONS DURING PREOPERATIONAL AND OPERATIONAL PERIODS. SEABROOK OPERATIONAL REPORT, 1992. MULTIPLE COMPARISDNS* SOURCE OF (Ranked in SPECIES VARIATION
- df SS Fb decreasing order)
(MONTHS USED) Winter flounder
- Preop-Op 1 1.78 20.61*** Preop >Op (Apr-Nov) Year (Preop-Op) 13 6.49 5.80***
Month (Year) 105 15.07 1.67*** Station 2 3.09 17.96*** S3 S2 S1 Preop-Op x Station 2 0.11 0.67 NS Error 419 d Rainbow smelt Preop-Op 1 0.04 0.35 NS to (Apr-Nov) Year (Preop-Op) 13 2.88 1.96* O.
~
Month (Year) 105 14.86 1.25 NS Station 2 2.85 12.60*** S3 S2 S1 Preop-Op x Station 2 0.02 0.10 NS Error 419 d Atlantic silverside Preop-Op 1 2.36 10.26** Preop >Op (Apr-Nov) Year (Preop-Op) 13 16.31 5.45*** Month (Year) 105 381.51 15.78*** Station 2 0.50 1.09 NS Preop-Op x Station 2 0.24 0.51 NS Error 419
- Preop-Op = Preoperational period vs. operational period Year (Preop-Op) = Year nested within preoperational and operational periods Month (Year) = Month nested within year b
NS = not significant (p>0.05)
* = significant (0.052p>0.01)
** = highly significant (0.012p>0.001)
*** = very highly significant (pso.001)
*1990 d
classified preoperational 1990 classified operational
" Underlining indicates no significant difference (a 5 0.05) in least squares means.
l FISH l l Rainbow smelt l .2 - Preoperational _j
.......... Operadonal
-o-- 1992 0.8 -
s b 0.6 - / \. e .- '2 3 j t \ ., , 04 ,.- , s ........,
\ /\
/
f
\ .*
'\
0.2 - d
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.w.. T~
* *l * * * * * *, *?{ ' ' ' _. - ~ * *, * * $ i y[ ' ' ' ' J JAN FEB MAR APR MAY JUN JUL AUG sEP OCT NOV DEC MONTil Figure 5 15. Log (x+1) catch per unit effort (mean number per 10 minute tow) for rainbow smelt; monthly means and 95% confidence intervals over all preoperational years (19761989) and monthly means for the operational years (1991 1992) and 1992 averaged over otter trawl Stations T1,T2 and T3. Seabrook Operational Report,1992.
Eginarine Soecies stations (Table 5-13). ANOVA results confirmed a significant reduction between Atlantic silverside the preoperational and operational periods ' (Table 5-16) . CPUE in the preoperational Atlantic silverside average is a common years of 1976, 1979, 1981 and 1980 was estuarine fish found in nearly every larger than all other years (NAI 1992). , inshore area in the Gulf of Maine (Bigelow CPUE in the operational year of 1992 was and Schroeder 1953). They are usually the lowest recorded during the study resident in nearshore areas year-round, (Table 5-16, NAI 1992). There were no where they spawn from May through July significant differences in CPtE during the (Whitlatch 1982). Atlantic silverside selected months among stations, but monthly mean CPUE in the seines was significant differences in CPUE occurred greatest in August through November for among years and months. both the preoperational and operational periods (Figure 5-141 Monthly mean catches in 1992 were lower than average 5.3.2.3 Imoinstement from July-December. As a result, the average catch in 1992 was lower than the An estimated total of 1,174 fish were average catch in 1991 and during the impinged at Seabrook Station in 1992 preoperational period at all three (Table 5-17). The greatest number of fish - 5-52
T6BIZ 5-17. NJMBER OF ORGANISPG IMPINCED AT SEABRC0K STATION 87 MONTH AND SPECIES DURING 1992. SEABRCDK OPERATIONAL REPORT.1992. SPECIES JAN FEB MAR APR MAY JUN JUL ADG SEP OCT* NOV DECb TOTAL PERCENT Pollock 1 64 23 1 142 231 19.68 Winter flounder 7 2 3 1 5 191 209 17.80 Windowpane 1 1 7 4 83 96 8.18 Longhorn sculpin 2 1 9 20 9 2 1 7 37 88 7.50 Rainbow smelt 4 1 2 60 47 5.71 Atlantic silverside 3 2 2 60 67 5.71 Sea raven i 2 8 7 6 4 1 5 21 55 4.68 Grubby 4 7 1 1 2 39 54 4.60 Skate sp. 10 1 1 2 34 48 4.09 Rock gunnel 2 1 1 2 11 3 20 40 3.41 Lumpfish 1 1 4 3 5 4 1 10 29 2.47 American sand lance 1 27 28 2.39 Atlantic cod 6 4 1 1 1 1 12 26 2.21 , Herring sp. 1 1 1 1 13 1 4 22 1.87 Shorthorn sculpin 1 3 1 1 11 17 1.45 Vryw uth 1 1 14 16 1.36 Eake sp. 15 15 1.28 Cunner 1 3 3 5 1 13 1.11 m Tautog i 2 6 9 0.77 American lobster 2 6 8 0.68 4 u Seasnail sp. 6 6 0.51 Unidentified 5 5 0.43 Threespine sticklebeck 3 3 0.26
' Ocean pout 3 3 0.26 Atlantic sackerel 2 1 3 0.26 American eel 3 3 0.26 Sea lamprey 1 1 1 3 0.26 Northern pipefish 1 1 2 0.17 Butterfish 2 2 0.17 Fourspot flounder 1 1 0.09 Red hake 1 1 0.09 Spiny dogfish 1 1 0.09 Searobin sp. 1 1 0.09 Cusk 1 1 0.09 Sculpin sp. 1 1 0.09 TUTAL 35 20 20 56 70 97 37 4 6 0 22 807 1174 100 Rate
- 1.93 1.19 1.11 3.24 3.89 5.45 2.01 0.22 0.66 0.000 1.30 4.62 6.18 Data provided by Tankee Atomic Electric Corporation.
" Circulating water syntes down during planned outage September 29, 1992 - October.24, 1992 b Includes an estimate of December 11-13, 1992 storm impact; the large volume of seaweed prevented performing actual counts. , *No. fish /10' gallons pumped.
i
l FISH i l (69%) were impinged in December, primarily rather than any effect of the operation during a strong riortheast storm on 11-13 of Seabrook Station. If a change between December (Figure 5-16). The impingement preoperational and operational periods had , rate (fish /10' gallons of cooling water) been limited to the nearfield stations, l was also greatest in December. The then it could possibly be related to { dominant species impinged were pollock, Seabrook Station. winter flounder, windowpane, longhorn sculpin, rainbow smelt and Atlantic f silverside, each of which accounted for 5.4.1.2 Selected Snecies I 5% or more of the total number of fish impinged. With the possible exception of Individual species also showed some , rainbow smelt, pollock and Atlantic sil- s ignificant dif f erences between preopera-verside, these fish are demersal species. tional and operational abundances. Five Few truly pelagic fish such as herring of nine selected species exhibited larval i species were impinged. Only seven rainbow densities that were lower in the opera-smelt and seven Atlantic silverside were tional period than they had been in the impinged until the storm in December of preoperational period, while two showed 1992, when an estimated additional 60 higher operational densities, and two individuals of rainbow smelt and Atlantic showed no significant difference (Table silverside each were impinged. Impinge- 5-19). Year to year variability in ment of windowpane and winter flounder abundances was significant for eight of ' i l. also increased greatly as a result of the the nine species. This may have contrib-December storm. uted to the significance of the operation- 1 al status factor in the analyses, but a ! l significant Preop-Op dif ference suggests 5.4 DISCUSSION there is a long-term trend above and beyond the typical interannual variabili-5.4.1 Ichthvoolankton ty. As was the case with the community analyses, such changes could not be 5.4.1.1 Community attributed to plant operation because changes in abundance observed at the The seasonal patterns of species nearfield stations also occurred at the assemblages identified by cluster analysis farfield station. This is shown by the were highly consistent between preopera- non-significance of the Preop /Op X Station tional and operational periods and among interaction term in the ANOVAs for all sampling stations for both fish eggs and nine selected species (Table 5-6). fish larvae. There were some statistical-ly discernable differences in abundances Significant differences between preoper-between the preoperational and operational ational and operational densities may be communities of eggs and larvae (Table 5- indicative of long-term trends in abun-18). These shifts in abundance were dances throughout the New Hampshire similar at both nearfield and farfield coastal area. Consistent decreasing stations, representing area-wide changes trends have been observed over the last 5-54
l' 20 - y \ '
. 1s -
88i o c. " 10 - o bA '5 w E$I I~ scheduled outage scheduled outage 0 i i i i e i i i e i I i i I i i i i i i i i e i JAN FEB MAR APR MAY AJN Et AUG SEP OCT NOV DEC JAN FEB MAR APR MAY EN Et ACO SEP OCT NOV DEC 1991 1992 807 250 - g 2x - wo Oh 150-5a 100 -
$,e-_
3 ?! ZA 50 - not - not sampled sampled 0 -- , , , , , , , , , , , , , , , , , , , , , , , , JAN IT.B MAR APR MAY JUN Et ALU SEP OCT NOV DEC JAN FEB MAR APR htAY JUN Et AUG SEP OCT NOV DEC 1991 1992 100 - 90 - 80 - j Z $ 0 M- \ / s y / *s / ss -s s W g
- (0 - s/ 's#,s's MMd s W / p/ge#
u 3 , muA e N~ 's h j I4 Mhg s MMut$ \ C .- s
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A i X mmh s s's's' -. sMM Ms8 s MIMMM /\s ; 30 - 's's A' Mh n ','s'
's 6' . 'pS stuuuuu
# ' 's 's ' ' Nth sMth s '
J:!4A MMMM M' ,' 3} - 33 g;;u ,- <p- ogr- s;;;;;;;ps ,s 10 , Mth not lMt' 0d [h Ngh 'INMN' not h
// 'l sampled jdjQ %@ y 4h. 4 Ig q;.j;;i 6'..l sampled 5-0 , , , , , , , , , , , , , , , , ,
, ; i JAN FEB MAR APR l'AY JUN Et AUG $EP OCT NOV DEC JAN FEB MAR APR MAY A1N Et AUG SEP OCT NOV DEC 1991 1992
@ Little skate C lenghom sculpin @ Immpfish
@ Pouock Windowpane Winter flounder 1
i Figure 516. Volume of coollng water pumped and fish impinged at Seabrook ) Station during 1991 and 1992. Seabrook Operational Report,1992. ; 1 1 1 5-55 I I
FIS!! TADLE S-18.
SUMMARY
OF POTENTIAL EFFECTS (DASED ON NUMERICAL CLASSIFICATION AND MANOVA RESULTS) 0F OPERATION OF SEABROOK STATION INTAKE ON INDIGEN0US ICimIYOPLANKTON COHHUNITIES. SEABROOK OPERATIONAL REPORT, 1992. DIFFERENCES BETWEEN OPERATIONAL AND l OPERATIONAL PERIOD PRE 0PERATIONAL PERIODS ) PLANKTON SIMIIAR TO CONSISTENT j COHHUNITY PREOPERATIONAL PERIOD?* AHONG STATIONS 7" , Fish eggs: I ' seasonal occurrence yes yes abundances no-Op< Preop in yes l ! several taxa 1 Fish larvae: seasonal occurrence yes yes q abundances no-variable among taxa yes j
- Based on results of numerical classification or HANOVA.
TABLE 5-19.
SUMMARY
OF POTENTIAL EFFECTS (BASED ON ANOVA FESULTS) 0F OPERATION OF SEADROOK STATION INTAKE ON ABUNDANCES OF SELECTED ICl!TIIY0 PLANKTON SPECIES. SEABROOK OPERATIONAL REPORT, 1992. DIFFERENCES BETWEEN OPERATIONAL AND I OPERATIONAL PERIOD PREOPERATIONAL PERIODS SIMILAR TO CONSISTENT i SPECIES PREOPERATIONAL PERIOD 7 AHONG STATIONS 7 American sand lance yes yes Winter flounder Op< Preop yes Atlantic cod Op> Preop yes Yellowtail flounder Op<Proop yes Atlantic mackerel Op> Preop yes Cunner- Op< Preop yes -l Hake yes yes . Atlantic herring Op< Preop yes , I Pollock Op< Preop yes 5-56
. .. .. ~ . . - . -. - - - . ._ -_ ._- -
i FISil several years in the Gulf of Maine stocks Although most species did not differ of winter flounder, yellowtall' flounder, significantly among the intake, discharge, Atlantic mackerel, red hake, white hake, and farfield stations, American sand lance Atlantic herring, and pollock (NOAA 1992), and winter flounder were less abundant in the farfield area than at least one of the A high level of similarity was observed nearfield stations. Both these species among stations in both the community have demersal eggs, a factor that could analyses and the selected species analy- contribute to spatial variation in ses. This is consistent with the observa- abundances of the larval stage because of tion in previous years that samples the decreased opportunity for dispersal collected on the same date at different from localized spawning localities stations resembled each other much more compared to species that have planktonic than samples collected at the same station eggs. i j one week apart (NAI 1983, 1984). Similar-ity of ichthyoplankton abundances and species composition among stations can be 5.4.1.3 Entrainment explained by the passive drifting of planktonic organisms and the dynamic The primary ef fect of the operation of nature of the water masses in the study Seabrook Station on ichthyoplankton is area. For example, during Februarythrough expected to be from entrainment through l April 1978 when American sand lance larvan the cooling water system. Comparison of were most abundant, reversing flood and previous years of entrainment data with ebb tidal current and longshore currents densities of nearfield ichthyoplankton has in the sampling area were typically 0.2 shown that species composition is general-to 0.6 knots about 75% of the time (NAI ly comparable, but that entrained densi-1980). Currents of this magnitude could ties are often substantially lower than transport a water mass about two nautical nearfield densities (NAI 1988, 1991, miles in a single tidal excursion, or 1992). These dif ferences are probably due about 8-24 km in 2n hours during periods to the different depths represented by dominated by longshore flow. The distance nearfield samples (oblique tows throughout from Station P2 to PS (2-3 km) or from P2 most of the water column) and entrainment i to P7 (4-5 km) is short enough that samples (the intake is located at mid-plankton communitles are transported from depth). Uneven depth distribution of fish one station to another in a matter of eggs and larvae., particularly at certain hours. Thus on the time scale of this times of the day, has been well documented study, in which samples are collected and (Smith et al. 1978, Kendall and Naplin compared over weeks, months, and years, 1981, Fortier and I,eggett 1983) and was the intake (P2), discharge (PS), and confirmed in the nearfield sampling area farfield (P7) stations may represent the (NAI 1981a, 1981b). As a result, when same " patch" of ichthyoplankton sampled eggs or larvae are most highly concentrat-5 l at different times, ed near the bottom or in the surface waters their vulnerability to entrainment is reduced. 5-57
b A a _ - - - - u - ' 2 - FISil The magnitude of ichthyoplankton substantially lower than those entrained entrainment at Seabrook Station in 1991 at Millstone, and 1992 was comparable to or lower than estimated total annual entrainment at The ultimate effect of entrainment other nuclear power plants at coastal losses on the balanced indigenous popula-marine locations in New England in recent tions of ichthyoplankton, as well as any years (Table 5-20). Cunner /tautog/ offects from the thermal discharge, is yellowtail flounder eggs entrained at measured by any changes to the nearfield Pilgrim, and cunner egg entrainment at ichthyoplankton communities that corre-Hillstone were both greater than the spond with the onset of operation of Seabrook estimates for entrained cunner / Seabrook Station. There were no communi-yellowtail flounder eggs. Annual on- ty-wide or selected species changes that trainment estimates for American sand corresponded with plant operation that did lance larvae at Seabrook were generally not occur in the farfield sampling area. lower than the entrainment estimates at Millstone and Pilgrim. The entrainment estimates for grubby larvae at Seabrook 5.4.2 Mult Fish were generally lower than the estimated number of grubby larvae entrained at 5.4.2.1 General Millstone and grubby and other sculpin larvae (#yoxocephalus spp. ) entrained at The fish community off flampton and Pilgrim. Entrained winter flounder larvae Seabrook, NII, was monitored for impacts at Seabrook, were comparable to the that included entrainment of larvae and estimated number entrained at Pilgrim, but impingement of adults. The estuarine fish TABLE 5-20. COMPARISON OF ENTRAINHENT ESTIMATES (x 10') AT NEW ENGLAND POWER PLANTS WIT 11 HARINE INTAKES. SEABROOK OPERATIONAL REPORT, 1992. SEABROOK SPECIES 1991 1992 PILGRIH" HILLSTONEb Cunner /yellowtail/ 716 199 1750 1534-4758 tautog eggs Sand lance larvae 37 18 108 5-190 Grubby larvae d 22 19 7.4 11-124 Winter flounder larvae 9 6 8.4 31-514 !
"MRI 1993. Cape Cod Bay b NUSCo 1993, 1979-1981 (eggs) or 1976-1992 (larvae). Long Is. Sound.
Seabrook: cunner /yellowtail; Pilgrim: cunner /tautog/yellowtail; Millstone: cunner. d Sdabrook, Millstone: grubby; Pilgrim: grubby and other sculpin. 5-58
l I , FISl! 1 I l community was monitored to determine if ties are not as strong as in the demersal there were any impacts due to the Browns fish community. The primary difference River discharge. Potential impacts were in pelagic fish community composition identified by trends in abundance between between the preoperational and operational the preoperational and operational periods periods was a relative decrease in that did not occur equally at the near- abundance of Atlantic herring, and an field and forfield stations for gill not increase in abundance of spiny dogfish and otter trawl collections, or did not (Table 5-21). Atlantic mackerel increased occur equally at all stations for seine in relative abundance, although CPUE collections, Other environmental influ- remained stable, ences such as long-term trends in fish abundance in the Gulf of Maine and Georges i Bank were considered in evaluating poten- Alinatic_.llarring tini operational effects, if any. Abundance of Atlantic herring has in-creased dramatically in the Gulf of Maine 5.4.2.2 Eg. ingle Fish (Table 5-21); however, CPUE has only increased slightly in the study area in Trends in the abundance of the pelagic recent years. CPUE of Atlantic herring fish community .in the study area are was significantly larger during the similar to trends that have occurred in preoperational period, primarily due to the Gulf of Haine; however the similari- extremely large catches in 1980. CPUE in TABLE 5-21.
SUMMARY
OF POTENTIAL EFFECTS OF OPERATION OF SEABROOK STATION INTAKE ON ABUNDANCES OF PELAGIC FIS!!. SEABROOK OPERATIONAL REPORT, 1992. DIFFERENCES BETWEEN OPERATIONAL AND OPERATIONAL PERIOD PREOPERATIONAL PERIODS l SIMILAR TO CONSISTENT AHONG LONG TERM ABUNDANCE l PARAHETER PREOPERATIONAL PERIOD 7" STATIONS?" TREND IN GULF OF HAINE h j Community Op<Proop yes increasing i Atlantic Op< Preop yes increasing l herring Atlantic yes yes increasing mackerel Pollock yes yes decreasing, stocks overexploited Spiny Op>Proop yes increasing dogfish 1
- Based on ANOVA results, except spiny dogfish NOAA (1992) 5-59
l FISH ; i i' 1992 of Atlantic herring was the largest crease in the CPUE of spiny donfish in the recorded since 1988 and may be starting study area cannot be attr: cod to the to increase in the study area. The lack operation of Seabrook Stnt - a because the of close agreement between the index of increase began prior to t.he commercial Atlantic herring abundance in the Gulf of operation of Seabrook Station, and it has Maine (NOAA 1992) and the CPUE data from occurred over a wide geographic area that ! the study area may be due to dif ferences extends throughout the Gulf of Maine, in sampling gear. The NMFS survey uses Georges Bank and middle Atlantic areas. a high-rise otter trawl to monitor pelagic fish abundance, while the monitor-ing in the study area is conducted with 5.4.2.3 Demersal Eish gill nets. General Mlantic MackcIn1 Many species (hake species, rainbow smelt, yellowtail flounder, and winter Atlantic mackerel abundance has remained flounder), showed a significantly lower steady in the study area and increased in CPUE during the operational period (Table the Gulf of Maine (Table 5-18). The index 5-22) that was a continuation of a trend of Age 1+ Atlantic mackerel biomass for that began in the early 1980s. This trend the Gulf of Maine has increased dramati- is not attributable to the operation of cally since 1983 (NOAA 1992). There were Seabrook Station because it began prior no significant differences in CPUE between to the operation of the station. The l decrease in the CPUE of demersal fish the preoperational and operational peri-ods, although CPUE in the operational year species in the study area is similar to of 1992 was the second highest recorded the decline in the indices of abundance to date, observed in the Gulf of Maine and Georges 4 Bank, with the exception'of hake species (NOAA 1992). The general decrease in Solny Do2 fish abundance of demersal fish in both the j study area and the Gulf of Maine-Georges j Until the early 1980s, spiny dogfish Bank area is probably due to a factor that CPUE in the study area was negligible. operates on a larger geographic scale than Since then, CPUE of spiry dogfish in- Seabrook Station, such as commercial creased to its present status as one of overfishing of demersal fish stocks, the five most abundant fish. The NMFS biomass estimate for spiny dogfish in the Gulf of Maine - middle Atlantic region has ((aken increased steadily since 1985 to record or near-record levels in 1990 and 1991 The average CPUE of hake species was (NOAA 1992). Spiny dogfish increased in significantly greater during tha preopera- j relative abundance from 2% in 1963 to 41% tional period than the operational period in 1986 (NOAA 1992). The dramatic in- (Table 5-22). Ilowever, the index of bio-5-60 1
FISil TABLE 5-22.
SUMMARY
OF POTENTIAL PLANT EFFECTS ON ABUNDANCE OF DEMERSAL FISHES. SEABROOK OPERATIONAL REPORT, 1992. OPERATIONAL DIFFERENCES BETVEEN PERIOD PREOPERATIONAL AND SIMILAR TO OPERATIONAL PERIODS LONG TERM PARAMETER PREOPERATIONAL CONSISTENT AMONG ABUNDANCE TREND IN MEASURED PERIOD" STATIONS
- GULF OF MAINE b Community Op< Preop Yes Decreasing Atlantic cod Op< Preop No Abundance index peaked' l in 1991, presently decreasing. Stocks overexploited.
Hake Op< Preop Yes Red hake: Increasing White hake: l No trend j Rainbow smelt Op< Preop Yes No information Yellowtail Op< Preop Yes Decreasing, stocks flounder over exploited l Winter Op< Preop No Decreasing, stocks i flounder over exploited l " Based on ANOVA results b Source: NOAA (1992) mass for red hake increased steadily since Winter Flounder the early 1980s, and the index of biomass for white hake has fluctuated without any The average CPUE of winter flounder was long-term trends since the early 1970s. significantly greater during the It is dif ficult to compare the indices for preoperational period at the nearfield red and white hake with the CPUE of station (T2) and one of the farfield combined hake species in the study. area, stations (T1) (Table 5-15). There was no This lack of specificity may contribute significant difference in CPUE between the to the apparent differing trends, preoperational and operational periods at However, the decrease in CPUE of hake the other farfield station (T3). The species in the study area began in the decrease in CPUE at the nearfield station mid-1980s and is likely not attributable is probably not due to the operation of to Seabrook Station, which became opera- Seabrook Station because the same trend tional in 1990. was observed at one of the farfield 5-61
1 l i l FISH stations that is beyond the influence of 1992) due to dif ferences in habitat. The reason for the decrease in CPUE at the the nearfield discharge. The index of winter flounder in the Gulf of Maine nearfield station in 1992 is unknown. The developed by the Massachusetts Division numbers of Atlantic cod captured in 1992 of Marine Fisheries (NOAA 1992) has and 1991 (NAI 1992) are so low that it is declined steadily since 1983 and in 1991 difficult to draw inferences about its was at its lowest point. The decrease in distribution and temporal changes in CPUE in the study area is similar to the abundance. Bottom water temperatures in trends oliserved in the Gulf of Maine and the operational period were significantly is probably due to the same cause - higher than the preoperational period at commercial overfishing. both nearfield and farfield stations, indicating regional warming (See Section 2.0). Very few Atlantic cod (26) were Rainbow Sm.elt impinged in 1992 (Table 5-17) and entrainment of eggs or larvae were The average rainbow smelt CPUE was relatively low compared to other species. significantly lower during the operational Therefore, the reduction in Atlantic cod period (Table 5 - 15 ) .- NMFS does not CPUE at the nearfield station may repre-provide an index of abundance for this sent a local distributional change, nearshore fish so it is not possible to track its abundance in areas other than the study area. However the decrease in 5.4.2.4 Estuarine Fish l CPUE of rainbow smelt was observed at both i nearfield and farfield otter trawl Mlan_ tic Silverside stations and therefore is not likely attributable to the operation of Seabrook The estuarine fish community was moni-Station. tored to determine any potential effects due to discharge from the settling basin or from operation of Seabrook Station. AtDntic Cod The dominant resident fish species in the estuary for both the preoperational and l CPUE of Atlantic cod decreased signif- operational periods was Atlantic silver-I icantly at all stations, but the decrease side. CPUE of Atlantic silverside was was significantly larger at the nearfield greatest during the first year of monitor-station (T2) (Table 5-15). The decrease ing, 1976, and declined steadily since l In CPUE at the nearfield station was then. Because this decline was observed especially pronounced in 1992, as only two at all stations (Table 5-23), and it began Atlantic cod were captured at this station prior to any potential plant impacts, it l during the entire year as opposed to 15 is most likely not due to the operation and 17 fish at each of the two farfield of Seabrook Station. stations (NAI 1993). CPUE of Atlantic cod has generally been lower at the nearfield station than the farfield stations (NAI 5-62 L___ _ __ _ _ . _ . _ _ _ _ _ _ _ . . _ _ _ ___ ._ - _ _ - - . _ . -
I 1 l FISH 1 l TADIE 5-23.
SUMMARY
OF POTENTIAL PLANT EFFECTS ON ADUNDANCE OF ESTUARINE FISHES. SEABROOK OPERATIONAL REPORT, 1992. DIFFERENCES BETWEEN PREOPERATIONAL AND OPERATIONAL PERIOD OPERATIONAL PERIODS SIMILAR TO CONSISTENT AHONG SPECIES PRE 0PERATIONAL PERIOD 7 STATIONS 7 Winter flounder Op< Preop Yes Rainbow smelt Yes Yes Atlantic silverside Op< Preop Yes Et,inbow Smcit the operation of Seabrook Station. The index of winter flounder abundance Rainbow smelt was an important, but decreased steadily in the Gulf of Maine highly variable member of the estuarine since 1983 (NOAA 1992) and the decreased fish community. Rainbow smelt CPUE varied abundance of winter flounder in the greatly both seasonally and annually, estuary may be a reflection of this CPUE was highest in the operational regional decline. period, primarily due to record catches in 1990. CPUE declined since 1990, but was within the range of preoperational 5.4.2.5 Imoinnement years. Operation of Seabrook Station appears to have had no effect on the Fish impingement was monitored at abundance of rainbow smelt. Seabrook Station to assess plant-related effects on the balanced, indigenous population within the coastal waters of htter_IIqundcI New Hampshire. It was expected that any potential effects due to the intake of Winter flounder composed only a small Seabrook Station would be detectable in portion of the estuarine fish community, the pelagic fish community. The intake averaging only 2% since 1976 (NAI 1992). structure withdraws water from the middle The majority of the winter flounder of the water column, which is the habitat captured in the seines were juvenile fish of the pelagic fish community. However, up to ago 2 (as aged by length frequency), the composition of the impingement CPUE of winter flounder in the seines was community was more similar to the demersal significantly lower during the operational fish community than the pelagic. Plant period. However, the decrease in CPUE in operat.i.ns have not resulted in the the operational period is the continuation impingement of large numbers of pelagic of a trend that began in 1980, prior to fish. 5-63
i FISl! ! The number of fish impinged, rate of storms has a large ef fect on the numbers fish impingement,'and species composition of fish impinged and the species composi-of the impingement community varied tion. between 1990 and 1992. The number of fish impinged increased from a low of 499 fish Impingement at Seabrook Station is less - in 1990 to a high of 1,174 in 1992. than any other electrical generating Similarly the rate of fish impingement station in New England with a marine increased from a low of 2.5 fish /10' intake (Table 5-24). The of fshore intake gallons of cooling water in 1990 to a high structure that withdraws water from the of 6.2 fish /10' gallons in 1992. Species middle of the water column appears to be composition also varied among years, minimizing entrapment, as designed. To although fsnr trends are becoming apparent put losses from impingement into perspec-with the collection of additional data: tive, the number of fish impinged at (1) impingement at Seabrook Station is Seabrook Station was compared to the lower than any other electrical generating estimated recreational catch of fishes in station in New England with a marine the marine waters of New Hampshire. The intake; (2) pollock, windowpane and winter National Marine Fisheries Service esti-flounder appear to be the fishes most mates that 1,584,000 marine fish were vulnerable to impingement at this station; captured by marine anglers in New Hamp- > (3) the demersal fish community appears shire in 1989, the most recent year for j to be the community most vulnerable to which statistics are available. Of these impingement; (4) the occurrence of strong fish, approximately 27% were released TABLE 5-24. COMPARISON OF IMPINGEMENT AT NEW ENGLAND POWER PLANTS WITH MARINE INTAKES. SEABROOK OPERATIONAL REPORT, 1992. STATION PERIOD NUMBER OF s'ISH IMPINGED ANNUALLY Pilgrim Station
- 1973-1992 1,143-87,752 mean = 18,418 1989* 3,472 SalemHarborElectrfc Genern.ing Statien 1974 39,578 Millstone Station d 1976-1988 16,266-511,387 mean = 101,953 Brayton Point Jan-Jun 12,231' Station
- 1992 Seabrook Station 1990 499 mean = 897 1991 1,019 1992 1,174
- Boston Edison (1993) bAnderson et al. (1975) 1989 is the most recent year for which data are available. '!
d NUSGo (1987)
% bert DeHart pers, comm., New England Electric 'Six month total only_(January-June) 5-64
- FISH alive, resulting in a harvest of 1,156,000 the windowpane resources of the study fish. Assuming that the marine recre- area, ational harvest in 1989 was of the same order of magnitude as 1992, fish losses Pollock, winter flounder and windowpane due to impingement at Seabrook Station can all be considered demersal fishes.
(1,174 fish) were negligible compared to The intake structure for Seabrook Station losses due to recreational harvest. removes water from the middle of the water Furthermore, a total of 1,437 fish were column. It was assumed that the fish captured in gill nets in the study area community most likely to be affected by as part of the effort to evaluate the impingement would be the pelagic fish potential impacts of the station. This community. The intakes were designed with monitoring ef fort resulted in the removal an of f-bottom intake with a velocity cap of about the same number of fish as were to minimize impingement of fish. The low impinged. numbers of fish impinged indicated that this lesign and its location are minimiz-Of those individuals impinged from 1990- ing pelagic impingement. However, it 1992, pollock (424), winter flounder (343) appears that the majority of the fish and windowpane (298) were the most nu- impinged are demersal fish. The fouling merous fish impinged at Seabrook Station community on the intake structure may (NAI 1991, 1992). attract demersal fish the way many demersal fish are attracted to areas Average pollock CPUE in gill nets was not around artificial reefs (Bohnsack et al. significantly different between the 1991). preoperational and operational periods. Impingement of this species does not One of the primary factors affecting the appear to be causing any significant number of fish impinged and the rate of impact. Average CPUE of winter flounder impingement appears to be the occurrence in trawls decreased in the operational of exceptionally strong northeast storms. period, particularly at the nearfield During both 1991 and 1992, large impinge-station. The impingement of 343 winter ment events occurred during strong flounder over three years from the study northeast storms. In 1991, 45% of all area is not likely to have caused any winter flounder were impinged in October measurable impact. CPUE of windowpane has and the majority of those fish were. not been analyzed as it was not one of the collected during and immediately af ter a species selected for impact analysis. storm on 29 October (NAI 1992). In 1992, 1 Mean CPUE of windowpane during the 69% of all fish were impinged in December. operational period was within the 95% and the majority of those fish were confidence interval of the preoperational collected during and af ter a strong storm mean, which indicates that windowpane on 11-13 December (Figure 5-16). Im-
- abundance has not decreased in the opera- pingement of all fish was lowest in 1990, ,
tional period. It is unlikely that the and no exceptionally strong northeast '! impingement of 298 windowpane over three storms occurred that year. Storm events years caused a substantial reduction in have been associated with increased 5-65 l 1 l n , - . , ,
~ - . . - . . - . ~
USII impingement in freshwater (Thomas and field and farfield stations, and (3) a similar decrease in the abundance of Hiller 1976; Lifton and Storr 1977). Winter flounder impingement was associated demersal fishes occurred in the Gulf of with storm events and sudden decreases in Maine and Georges Bank due to commercial water temperature at the Hillstone overfishing (NOAA 1992). Generating Station (NUSCo 1987). The mechanism for increased impingement during As with most other demersal fishes, CPUE storm events is unknown, but it is of Atlantic cod decreased during the possible that the increased turbulence may operational period at all stations. cause demersal fish to be more vulnerable Unlike any of the other demersal fishes, . to impingement. The bottom turbulence the decrease was significantly greater at during the storm of 11-13 December 1992 the nearfield station than the farfield was strong enough to move 1,500 pound gill stations, indicating a possible correla-net moorings located in 60 feet of water, tion to plant operation. The decrease in This turbulence was undoubtedly strong CPUE at the nearfield station in the enough to lif t flounders and demersal fish operational period appears to be primarily of f the bottom and into the water column due to low catches for all months except where they could have become disoriented June. The reason for the low catches is and vulnerable to impingement. not clear, and may be due to the discharge causing a local distributional change or may be simply part of natural variability. 5.4.2.6 Effec 15 of Station Oooration The decrease in CPUE does not appear to be due to increased bottom water tempera-With the possible exception of Atlantic tures, changes in habitat, or impingement cod, the operation of Seabrook Station had and entrainment. Only 72 Atlantic cod no measurable effects on the nearshore were impinged between 1990 and 1992 and fish populations of the study area. The it is unlikely that the removal of this pelagic fish community in the study area many fish could affect the Atlantic cod appeared to be increasing in abundance in resources of the study area. Atlantic cod 1992 due to larger CPUE of Atlantic are mobile fish capable of large scale herring, Atlantic mackerel and spiny movements (Bigelow and Schroeder 1953). l dogfish (Table 5-21). These three species If plant operations are affecting Atlantic are also increasing in abundance in the cod abundance in the nearfield area, they Gulf of Maine - Georges Bank areas due to would probably respond by avoiding the changes in the patterns of commercial areas affected and moving to adjacent fishing (NOAA 1992). The demersal fish areas. The status of Atlantic cod in the community continued to decrease in abun- nearfield area will continue to be
- i. dance during the operational period, but monitored in future studies, was probably not due the operation of l
Seabrook Station beccuse (1) the trend began in the early and mid-1980s before the operation of Seabrook Station, (2) the decrease occurred equally at both near-l
- j. 5-66 l
l l
FISH 5.5 LITERATURE CITED Fortier, L., and W. C. Leggett. 1983. Vertical migrations and transport of Anderson, C.O., D.J., Brown, B.A. larval fish in a partially mixed Ketschke, E.M. Elliott and P.L. Rule, estuary. Can. J. Fish. Aquat. Sci. 1975. The effects of the addition of 40(10):1543-1555. a fourth generating unit at the Salem Harbor Electric Generating Station on Harris, R.J. 1985. A primer of multi-the marine ecosystem of Salem Harbor. variate statistics. Academic Press, Massachusetts Division of Marine Orlando. 575 pp. Fisheries, Department of fisheries, Wildlife and Recreational Vehicles. Howe, A.B., and P.G. Coates. 1975. Winter flounder movements, growth and Bigelow, H. B. , and W.C. Schroeder. 1953. mortality of f Massachusetts. Trans. Fishes of the Gulf of Maine. U. S. Fish Amer. Fish. Soc. 104(1):13-29. Wildl. Serv. , Fish. Bull. 53(74):1-577. Kendall, A.W., Jr., and N.A. Naplin. Bohnsack, J.A., D.L. Johnson, and R.F. 1981. Diel-depth distribution of summer Ambrose. 1991. Ecology of artificial ichthyoplankton in the Middle Atlantic reef habitats and fishes. Puges 61-108 Bight. Fish. Bull. , U. S. 79(4):705-726. in W. Seaman and L.M. Sprague, eds. Artificial habitats for marine and Lif ton, W. S. , and J.F. Storr. 1978. The j freshwater fisheries. Academic Press, effect of environmental variables on l Boston. fish impingement. Pages 299-311 in L.D. , Jensen, ed. Fourth national workshop on I Boston Edison. 1993. Impingement of entrainment and impingement. Ecological organisms at Pilgrim Nuclear Power Analysts Inc. Melville, NY. 424 pp. Station (January-December 1992). In Marine ecology studies related to Marine Research, Inc. (MRI). 1993, operation of Pilgrim Station. Semi-ann. Ichthyoplankton entrainment monitoring l Rep. 41. Boston Edison Company, at Pilgrim Nuclear Power Station l January-December 1992. Vol. 2. (Impact Clif ford, H.T. , and W. Stephenson. 1975. perspective). In Marine ecology studies An introduction to numerical classifica- related to operation of Pilgrim Station. tion. Academic Press, New York. 229 Semi-ann. Rep. 41. Boston Edison pp. Company. Faber, D.J. 1976. Identification of four Normandeau Associates Inc. (NAI). 1980. northern blonniold fish larvae in the Annual summary report for 1978 hydro-Canadian Atlantic Ocean (Stichaeidae, graphic studies off Hampton Beach, New Lumpenidae). J. Fish. Res. Board Can. Hampshire. Preoperational ecological 33(8):1798-1802. monitt, ring studies for Seabrook Station. Tech. Rep. X-2. 5-67
FISH
. 1981a. Seabrook Environmen- tional study for Seabrook Station, tal Studies, l'979. Finfish ecology Tech. Rep. XVIII-II.
Investigations in Hampton-Seabrook estuary and adjoining coastal waters. . 1988. Seabrook Environmental Tech. Rep. XI-2. Studies, 1987. A characterization of baseline conditions in the Hampton-1981b. Seabrook Environmen- Seabrook area, 1975-1987. A preoperat-tal Studies. 1980 data report. Tech. lonal study for Seabrook Station. Tech. Rep. XII-2. Rep. XIX-II.
. 1982. Seabrook Environmental . 1989. Seabrook Environmental Studies, 1981. A characterization of Studies, 1988. A characterization of baseline conditions in the Hampton- baseline conditions in the Hampton-Seabrook area, 1975-1981. A preopera- Seabrook area, 1975-1988. A preopera-tional study for Seabrook Station. tional study for Seabrook Station.
Tech. Rep. XIII-3. Tech. Rep. XX-II. 1983. Seabrook Environmental . 1990. Seabrook Environmental Studies, 1982. A characterization of Studies. 1989. A characterization of baseline conditions in the Hampton- baseline conditions in the Hampton-Seabrook area, 1975-1982. A preopera- Seabrook area, 1975-1989. A preopera-tionni study for Seabrook Station. tional study for Seabrook Station. Tech. Rep. XIV-II. Tech. Rep. XXI-II.
. 1984 Seabrook Environmental . 1991. Seabrook Environmental Studies, 1983. A characterization of Studies, 1990. A characterization of baseline conditions in the Hampton- environmental conditions in the Hamptot.-
Seabrook area, 1975-1983. A preopera- Seabrook area during the operation of tional study for Seabrook Station. Seabrook Station. Tech. Rep. XXII-II. Tech. Rep.'XV-II.
. 1992. Seabrook Environmental 1985. Seabrook Environmental Studies, 1991. A characterization of Studies, 1984. A characterization of environmental conditions in the Hampton-baseline conditions in the Hampton- Seabrook area during the operation of Seabrook area, 1975-1984. A preopera- Seabrook Station. Tech. Rep. XXIII-I.
tional study for Seabrook Station. ; Tech. Rep. XVI-II. . 1993. Seabrook Environmental l Studies. Unpublished 1993 data tables. j
. 1987. Seabrook Environmental Studies, 1986. A characterization of National Oceanic and Atmospheric Adminis-baseline conditions in the Hampton- tration (NOAA). 1991. Marine recro-Seabrook area, 1975-1986. A preopera- ational fishery statistics survey.
Atlantic and Gulf coasts, 1987-1989. ; 5-68 l I
FISH Current Fisheries Statistics Number Amer. Fish. Soc. Special Pub. 20. 174 8904. National' Oceanic and Atmospheric pp. Administration, Mational Marine Fisher-les Service, Fisheries Statistics Saucerman, S.E., and L.A. Deegan, 1991. Division, Silver Spring, MD. Lateral and cross-channel movement of young-of-the-year winter flounder
. 1992. Status of fishery (Pseudopleuronectas americanus) in resources off the northeastern United Waquoit Bay, Massachusetts. Estuaries States for 1992. NOAA Tech. Memo. NMFS- 14(4)*440-446.
F/NEC-95. 133 pp. ! Smith, W.G., J.D. Sibunka, and A. Wells. Northeast Utilities Service Company 1978. Diel movements of yellowtail (NUSCo). 1987. Monitoring the marine flounder, Limanda terruginea, detemined environment of Long Island Sound at from discrete depth sampling. Fish. Millstone Nuclear Power Station. . Bull., U.S. 76(1):167-178. Summary of studies prior to Unit 3 operation. Sneath, P.H.A., and R.R. Sokal. 1973. Numerical taxonomy. The principles and
. 1993. Monitoring the marine practice of numerical classification.
environment of Long Island Sound at W.H. Freeman Co., San Francisco. 573 Millstone Nuclear Power Station. 1992 pp. annual report. Thomas, D.L., and G.J. Miller. 1976. Oullet, P., and D.D. Dodson. 1985. Impingement studies at the Oyster Creek Dispersion and retention of anadromous Generating Station, Forked River, New rainbow smelt (Osmerus mordax) larvae Jersey, from September to December 1975. In the middle estuary of the St. Pages 317-341 in L.D. Jensen, ed. Third Lawrence River. Can. J. Fish. Aquat. national workshop on entrainment and Sci. 42(2):332-341. impingement. Ecological Analysts Inc. Melville, NY. 425 pp. Richards, S.W. 1982. Aspects of the biology of Ammodytes americanus from the Whitlatch, R. B. 1982. The ecology of New St. Lawrence River to Chesapeake Bay, England tidal flats: a community 1972-75, including a comparison of the profile. U.S. Fish and Wildlife Long Island Sound postlarvae with Service, Biological Services Program, Ammodytes dubius. J. Northwest Atl. Washington, D.C. FWS/0BS-81/01. 125' Fish. Sci. 3:92-104. pp. 7. Robins, C.R. , R.M. Bailey, C.E. Bond, J.R. Brooker, E.A. Lachner, R.N. Lea, and W.B. Scott. 1991. A list of common and scientific names of fishes from the United States and Canada. 5th ed. 5-69
APPENDIX TABLE 5-1. FlhTISH SPEClES COMPOSITION BY LIFE STAGE AND GEAR JULY 1975-DECEMBER 1992. SEABROOK OPERATIONAL REPORT, 1992. ICHTHY 0 PLANKTON ADULT AND JUVENILE TOWS FINFISH GILL ECCS LARVAE TRAWLS NETS SEINES SCIEhilFIC NAME" COMMON NAME* b Acieenser oxyrhynchus Atlantic sturgeon R Mgg agitiYalis blueback herring - R C C Mgsa rediocris hickory shad - R Mgn oseudoharenaus alevife - 0 0 0 81gg gapidittima Americanshad - R 0 0 Algiasp. R Armodytesacericanus American sand lance A 0 R 0 6aarbichasigpu Atlantic volffish R Anchoa hepsetus striped anchovy R Anquillarostrata Americaneel C R AgitM Endrang fourspine stickleback R &tqbg ntgg probatocechalug sheepshead R Aspjdochoroidesmonoptervatus alligatorfish C 0 Brevoortia tyrannus Atlantic menhaden 0 0 R 0 R HIggg htga g cusk 0 0 Ca,n g hippga crevallejack R qutigpttglig gitiata black sea bass R R Concer oceanicu conger eel R CLgpgahaHDan Atlantic herring C 0 A 0 Cryotacanthodes maculatus vrycouth 0 R Cyllgpigagigaps lumpfish C R R R Eqshelycon cirbilus fourbeard rockling C C 0 [gndgigssp mummichog C QadggJ9fhgA Atlantic cod - C C 0 R Gaiug!fglancararmus Atlantic cod / haddock C Gatt_elgstngsp.d stickleback R R C Glyotocechalgtsyngq1ogs g witch flounder C C 0 Huitriptets americanus sea raven 0 0 0 R Hjpmalossoides olatessoidu American plaice C C 0 Hippoalossus hipmalossus Atlantic halibut R Labridae/Pleuronectes cunner /yellowtail flounder
- A - -
Lipartsatlanticus Atlanticseasnail R C - - - Lipartsgghegl gulfsnailfish C - - - Liparis sp. snailfish R 0 Lo 0 0 R-J hin a.grlgang goosefish R Lgeg an larptstaeformis 8 snakeblenny 0 R Lgsgua raculatus daubed shanny R R Kacrotoareggamericanus ocean peut 0 C R Helancarammus aealefines haddock - 0 C R Mgaidiarenidia Atlanticsilverside R 0 R A Menticirrhus saxatilis northernkingfish R Merluccius bilinearis Atlantic whitingh C C C C R (continued) 5-70
^1 1
APPENDIX TABLE 5-1. (Continued) ICHTHYOPLANKTON ADULT AND JUVENILE TOWS EINFISH CILL SCIENTIFIC NAME* COHHON NAME" ECCS LARVAE TRAWLS K6TS SEINES 'Microcadug toccod Atlantic toscod R R 0 Morone amatigg white perch R
}{gtongtaxatills striped bass R R tiggjlcephalus striped mullet R Uustelug ggA11 smooth dogfish R HYoxoceobalus aengua grubby C 0 2 0 hyonocechalus octodecerseinosus longhorn sculpin C A 0 R l WYoxocechalg ggIgin shorthorn sculpin C 0 R R l Odontaspig taurus sand tiger R l Oncorhynchus kisutch coho salmon R R Oncorhynchusp31sg rainbow trout R d
Osmerus int.a3 rainbow smelt 0 0 0 C Paralichttygdentatus summer flounder R R Paralichthysgblgaqu foutspot flounder R 0 C R [gpI11g triacanthus butterfish 0 0 R 0 R [gtromnon gring sealamprey R thaligaunnellus rockgunnel C 0 R R Pleuronecteg americanus vinter flounder C C 0 C Pleuronectes ferruaineus yellowtail flounder - C A R R
&lguronectesputnami smooth flounder R R C foll gbig virens pollock C C C C 0 Eggiggu ullattig bluefish 0 0 frionotuscarolinus northern searobin - -
0 R Erigiq1g evolans striped searobin - - R Prionotut sp. searobin 0 R - - - Punattiuggunqitig ninespine stickleback C Raigsp* skate C R 1g10gtrutta brown trout 0 Salvelinus {gatjaalig brook trout R SqgehgI laponicus chub mackerel R i Eggthtt agggktu Atlantic mackerel A A R C R Scoobthalmqs,aquesus windovpane C C C R 0 Sebastessp.3 redfish 0 Sphoeroidesmaculatus northern puffer R R gggly; acanthia; spiny dogfish R C itenotomuschrysope scup R 0 R Stichaeus ounctatus Arcticshanny 0 SynanathugLugg northern pipefish C 0 R 0 j 1.ltgggonitis a tautog - C R 111tgggLatngadspitgg cunner - A 0 0 R forpedonobiliana Atlantictorpedo R II1g[gpg ratnyl moustache sculpin 0 R ylntigsubbifurcata radiated shanny C 0 Urgpby.C118P.k bake A C A 0 C Ecotnotes: See next page. 5-71 ] l
l l l l APPENDIXTABLE5-1, (Continued) footnotes:
- Names are according to Robins et al. (1991) unless otherwise noted. Taxa usually identified to a different level are not included in this list to avoid duplication (e.g., Gadidae, Enchelvoous/Urochycis, Hvoxocephalus sp.,
UrochYcis GjlMS b0ccurrence of each species is indicated by its relative abundance or frequency of occurrence for each life stage or gear type: A - abundant (2107, of total catch over all years) C - common (occurring in 210% of samples but < 10% of total catch) 0 - occasional (occurring in ( 10 and 21% of samples) R - rare (occurring in < 1% of samples)
- not usually identified to this taxonomic level at this life stage Predominantly ba@lg beteroclitis, mummichog, but may include a small number of fundulus maialis, striped killifish.
$wo species of Casteresteg have been identified from seine samples: Q.aculeatus,threespinestickleback:and Q. yhigl.pAdl, blackspotted stickleback (both occurring commonly).
- Nay also include a small number of tautog.
'Three species of Ljpatig have been identified from trawl samples: L.atlanticus,L.coheni,andL.incullinus (inquiline snallfish). 9 Spelling after Faber (1976). Nreviouslycalledsilverhake: Atlantic whittag was recommended by Kendall and Naplin (1981:707). I FourspeciesofEalahavebeenidentifiedfrostrawlsamples: E. fadiata, thorny skate (cormon): E.erinacea, little skate (common): E. qqg1 Lata, vinter skate (occasional): andE.eclanteria,cleatnoseskate(rare). 35th_aglej norvecicus (previously called (. Italing), J. pentella and g, fasciatus have been reported to occur in the northwest Atlantic. SebasterincoastalNewHampshirewatersareprobablyS. fasciatus,goldenredfish (Dr. Bruce B. Collette, U.S. National Museum, pers. come. April 1982), but larval descriptions are insufficient to allow distinction among the three species. Nhree species of Vrophycis have been identified from trawl samples: 9. chgs, red hake (common): 2. Iggig, white hake (common): andU.Iggia,spottedhake(rare). l l 5-72
TABLE OF CONTENTS PACE 6,0 MARINE MACROBENTHOS . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 6.1 OBJECTIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 6.2 METHODS . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 6.2.1 Field Methods . . . . . . . . . . . . . . . . . . . . . . . 6 6.2.2 Laboratory Methods . . . . . . . . . . . . . . . . . . . . 6-2 6.2.3 Analytical Methods . . . . . . . . . . . . . . . . . . . . . 6-3 6.2.3.1 Community . . . . . . . . . . . . . . . . . . . . 6-3 6.2.3.2 Selected Species . . . . . . . . . . . . . . . . . .6-6 6.3 RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6 6.3.1 Marine Macroalgae . . . . . . . . . . . . . . . . . . . . 6-6 6.3.1.1 Horizontal Ledge Communities , , . . . . . . . 6-6 6.3.1.2 Selected Species . . . . . . . . . . . . . 6-24 6.3.2 Marine Macrofauna . . . . . . . . . . . . . . . . . . . 6-26 6.3.2.1 Horizontal Ledge Communities . . . . . . . . . . . 6-26 6.3.2.2 Selected Benthic Species . . . . . . . . . . . . 6-43 6.4 DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . 6-55 6.4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . 6-55 6.4.2 Potential Discharge Effects on Intertidal / Shallow Subtidal Benthic Community . . . . . . . . . . . . . 6-55 6.4.2.1 Background . . . . . . . . . . . . . . . . . . . 6-55 6.4.2.2 Intertidal Benthic Community . . . . . . . . . . . 6-56 6.4.2.3 Shallow Subtidal Benthic Community . . . . . . . . 6-58 6.4.3 Potential Detrital Effects on the Mid-Depth and Deep Benthic Community . . . . . . . . . . . . . . . . . . . . . 6-58 6.4.3.1 Background . . . .. . . . . . . . . . . . . . . 6-58 6.4.3.2 Mid-Depth Benthos . . . . . . . . . . . . . . . . 6-59 6.4.3.3 Deep Benthic Community . . . . . . . . . . . . . 6-61 6.4.3.4 Effects of Seabrook Station Operation . . . . . . . 6-61 6.5 LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . 6-61 6-1
, . ~ _ - -.
4 4 LIST OF FIGURES PAGE 6-1. Marine benthic sampling stations . . . . . . . . . . . . . . . . . 6 6-2. Preoperational (through 1989) median and range and 1991 and 1992 values of number of taxa collected in triannual general algae collections at Stations B1MSL, B1MLW, B17, B19, B31 (1978-1992), B5MSL, B5MLW, D35 (1982-1992),- and annual collections at B16 (1980-1984; 1986-1992), B13, B04 (1978-1984; 1986-1992) snd B34 (1979-1984; 1986-1992) . . . . . . . . . . . . . 6-8 6-3. Dendrogram and station groups formed by year formed by numerical classification of August collections of marine benthic algae, 1978-1992 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-14 6-4. Dendrogram and station groups by year formed by numerical classification of August collections of marine macrofauna, 1978-1992 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-34 2 l l l
)
r 4 1 l l 6 11 1
--- , ,. . . . . _ _1
'l LIST OF TABLES PAGE 6-1. SELECTED BENTHIC TAXA AND PARAMETERS USED IN ANOVA OR WILCOXON'S SUMMED RANKS TEST . . . . . . . . . . . . . . . . . . 6-4 6-2. PREOPERATIONAL MEAN AND 95% CONFIDENCE LIMI1S AND 1992 AND OPERATIONAL MEAN NUMBER OF TAXA, TOTAL BIOMASS, AND C#0NDRUS CRISPUS BIOMASS COLLECTED AT INTERTIDAL, SHALLOW SUBTIDAL, MID-DEPTH, AND DEEP BENTHIC STATIONS . . . . . . . . . . 6-9 6-3. RESULTS OF ANALYSIS OF VARIANCE OF NUMBER OF TAXA (per 8
1/16 m*) AND TOTAL BIOMASS (g per m ) 0F MACR 0 ALGAE COLLECTED IN AUGUST AT IKTERTIDAL, SHALLOW SUBTIDAL, AND DEEP STATION PAIRS, 1978-1992 . . . . . . . . . . . . . . . . 6-10 6-4.
SUMMARY
OF SPATIAL ASSOCIATIONS IDENTIFIED FROM NUMERICAL CLASSIFICATION (1978-1992) 0F BENTHIC MACROALGAE SAMPLES COLLECTID IN AUGUST . . . . . . . . . . . . . . . . . . . 6-15 6-5. A COMPARISON OF SPARSELY OCCURRING MACROALGAE TAXA IN AUGUST BENTHIC DESTRUCTIVE SAMPLES DURING THE PREOPERATIONAL PERIOD (1978-1989) AND THE OPERATIONAL PERIOD (1990, 1991 AND 1992) . . . . . . . . . . . . . . . . . 6-18 6-6. PRE 0PERATIONAL MEAN AND 95% CONFIDENCE LIMITS, 1992 AND OPERI.TIONAL MEANS, AND RESULTS OF WILCOXON'S SUMMED RANK TEST COMPARING NUMBERS OF FOUR KELP SPECIES AND PERCENT FREQUENCIES OF THREE UNDERSTORY ALGAL TAXA BETWEEN OPERATIONAL AND PREOPERATIONAL PERIODS . . . . . . . . . . . . . 6-20 6-7. PERCERT COVER AND PERCENT FREQUENCY OF DOMINANT PERENNIAL 2 AND ANNUAL MACR 0 ALGAL SPECIES PER 0.25 m AT FIXED INTERTIDAL NON-DESTRUCTIVE SITES DURING THE PRE 0PERATIONAL AND OPERATIONAL PERIOD . . . . . . . . . . . . . . . . . . . . . . 6-22 6-8. PREOPERATIONAL MEAN AND 95% CONFIDENCE LIMITS, 1992 AND OPERATIONAL MEANS AND RESULTS OF WILC0XON'S SUMMED RANKS TEST COMPARING PERCENT FREQUENCIES OF FUCOID ALGAE AT WO FIXED TRANSECT SITES IN THE MEAN SEA LEVEL ZONE BEWEEN THE PREOPERATIONAL AND OPERATIONAL PERIODS . . . . . . . . . . . . 6-25 6-9. RESULTS OF ANALYSIS OF VARIANCE OF C#0NORUS CRISPUS BIOMASS (g/m 2) AT INTERTIDAL AND SHALLOW SUBTIDAL STATION
' PAIRS FOR THE PREOPERATIONAL AND OPERATIONAL (1991 AND 1992) PERIODS . . . . . . . . . . . . . . . . . . . . . . . . . . 6-27 6-111 1
~1
-. . ~ . ._
l 1 PACE 6-10. PREOPERATIONAL MEAN AND 95% CONFIDENCE LIMITS AND 1991, 1992 AND OPERATIONAL MEAN NUMBER OF TAXA (per 1/16ml ) AND GEOMETRIC HEAN DENSITY (No./m*) FOR TOTAL DENSITY (NON-COLONIAL MACROFAUNA) SAMPLED IN AUGUST AT INTERTIDAL, SHALLOW SUBTIDAL, MID-DEPTH- AND DEEP STATIONS . . . . . . . . . . . 6-28 6-11. RESULTS OF ANALYSIS OF VARIANCE OF NUMBER OF TAXA (por 1/16 m )2 AND TOTAL DENSITY (per m') 0F MACROFAUNA COLLECTED IN AUGUST AT INTERTIDAL, SHALLOW, MID-DEPTil, AND DEEP SUBTIDAL STATIONS 1978-1992 . . . . . . . . . . . . . . . . . . . . 6-29 6-12. STATION GROUPS FORMED BY CLUSTER ANALYSIS WIllt PRE 0PERA-TIONAL AND OPERATIONAL (1990-1992) GEOMETRIC MEAN DENSITY AND 95% CONFIDENCE LIMITS FOR ABUNDANT MACROFAUNAL TAXA (NON-COLONIAL) COLLECTED ANNUALLY IN AUGUST FROM 1978 TifROUGH 1992 . . . . . . . . . . . . . . . . . . . .'. . . . . . 6-32 6-13. PERCENT FREQUENCY OF OCCURRENCE BY SEASON AND OVER ALL 2 SEASONS OF THE DOMINANT FAUNA WITHIN PERMANENT 0.25m QUADRATS AT THE UPPER (BARE ROCK), MID- (FUCOID ZONE) AND LOWER (Chondrus ZONE) INTERTIDAL ZONES AT NEARFIELD B1 (OUTER SUNK ROCKS) AND FARFIELD BS (RYE LEDGE) DURING Tite PRE 0PERATIONAL AND OPERATIONAL (1991-92) PERIODS AND IN 1992 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-37 6-14. ESTIMATED DENSITY (per 0.25 m 8) 0F SELECTED SESSILE TAXA. ON HARD-SUBSTRATE BOTTOM PANELS EXPOSED FOR FOUR MONTilS AT STATIONS B19 AND B31 SAMPLED TRIANNUALLY ( APRIL, AUGUST, DECEMBER) FROM 1981-1992 (EXCEPT 1985 AND 1990) . . . . . . . . . . 6-42 6-15. GEOMETRIC MEAN DENSITY (NO./SQ. METER) AND UPPER AND LOWER 95% CONFIDENCE LIMITS AND 1992 AND OPERATIONAL MEANS FOR SELECTED BENTHIC MACROFAUNAL SPECIES AT NEARFIELD-FARFIELD STATION PAIRS . . . . . . . . . . . . . . . . . 6-44 6-16. RESULTS OF ANALYSIS OF VARIANCE COMPARING LOG-TRANSFORMED DENSITIES OF SELECTED BENTHIC SPECIES AT NEAR- AND FAR-FIELS STATION PAIRS (B1HLW/B5MLW, B17/B35, B19/B31) DURING PREOPERATIONAL (TI(ROUGH 1989) AND OPERATIONAL (1991 AND 1992) PERIODS . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-45 6-17. MEAN LENGTH (HM) AND UPPER AND LOWER 95% CONFIDENCE LIMITS DURING THE PREOPERATIONAL PERIOD AND 1992 AND OPERATIONAL MEANS FOR SELECTED BERI' HIC' SPECIES AT NEARFIELD-FARFIELD STATION PAIRS . . . . . . . . . .. . . . . . . . . . . . . . . . . . 6-49 6-18. MEAN DENSITIES (per m ) 8AND RANGE DURING THE PREOPERATIONAL PERIOD (1985-1989) AND MEAN IN 1991 AND 1992 0F ADULT
~
SEA URCHINS . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-54 6-iv
.. . - - _ - _ . . . = . .
d PAGE 6-19.
SUMMARY
OF EVALUATION OF DISCHARGE PLUME EFFECTS ON THE BALANCED INDIGENOUS BENTHIC COMMUNITIES IN VICINITY OF SEABROOK STATION . . . . , . . . . . . . . . . . . . . . . . . . . 6-57 6-20.
SUMMARY
OF EVALUATION OF DISCHARGE PLUME EFFECTS ON REPRESENTATIVE IMPORTANT SPECIES IN VICINITY OF SEABROOK STATION . . . . . . . . . . . . . . . . . . . . . . . . . 6-57 4 6-21.
SUMMARY
OF EVALUATION 0F DETRITAL RAIN EFFECTS ON THE BALANCED INDIGENOUS BENIliIC COMMUNITIES IN THE VICINITY OF SEABROOK STATION . . . . . . . . . . . . . . . . . . . . . . . . 6-60 6-22.
SUMMARY
OF EVALUATION OF DETRITAL EFFECTS ON REPRESENTATIVE IMPORTANT BENTHIC SPECIES . . . . . . . . . . . . . . . . . . . 6-60 4 l l l 6-v l
- l l
HARINE HACROBENTHOS 6.0 MARINE MACROBENTHOS 6.2 HETHODS 6.1 ODJECTIVES 6.2.1 Field Methods The objective of the marine macrobenthic Quantitative (destructive) samples of program is to identify annual and spatial macrofauna and macroalgae were collected trends in the macroalgal and macrofaunal triannually at six benthic stations; three communities and selected benthic species, nearfield-farfield station pairs repre-and to determine if there are any measur- senting the lower intertidal (B1MLV, able ef fects on the benthic macroalgal and B5HLW), shallow subtidal (4.6 m; B17, B35) macrofaunal communities and selected and mid-depth (9-12 m; B19, B31) loca-important species due to the operation of tions. Sampling was conducted at four Seabrook Station. The potential ef fects additional stations in August only. This that were investigated are those consid- included one mid-depth intake station ered to be most likely to affect the ben- (B16) and three deep (18-21 m) stations thic habitat. These include exposure to (nearfield-B13 and B04, and f arfield-B34; both the surf ace-oriented thermal plume, Figure 6-1). Sampling for this program most likely at intertidal and shallow began in 1978 with five nearfield stations 'subtidal (4.6 m) depths, and increased (B1, B04, B13, B17, B19) and one f arfield detritus from entrained organisms, most station (B31). Nearfield Station B16 was likely in the vicinity of the discharge added to the study in 1979 and three area. f arfield stations were added in 1980 (B34) N l W""
+ . ,.
i i u- ?~ umi N- I 2F t##! gwj "',* 3E.
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LEGEND sa m O = benthic samples
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liI)
$ Im,'**%g/~ f4f" we
* % (
,,,w mag;
'%'ll Ja ~
N m=< '- tV N/ A i ummun . f Figure 61. Marine benthic sampling stations. Seabrook Operational Report,1992. 6-1
HARINE HACROBENT110S and 1982 (B35, B5). All organisms were occurrence of fucold algae was recorded removed from five' randomly selected 1/16 along a 9.5-m transect line (NAI 1991a). m2 (0.0625-m8 ) areas on rock surfaces. ' Epifauna and flora were scraped from rock Subtidal transects were established in - surfaces. Subtidal collections were drawn 1978 to monitor larger macroinvertebrates through a diver-operated airlift into a and macroalgae that are not adequately 0.79-mm mesh bag, placed in a labeled represented in the destructive samples. I plastic bag, brought to the surface, and Six randomly placed replicate 1-m x 7-m , sent to the laboratory for preservation band transects were surveyed at nearfield-and processing (NAI 1991a). Intertidal farfield station pairs in the shallow collections used a similar procedure but subtidal (B17, B35) and mid-depth (B19, i did not use an airlift. B31) zones in April, July and October. The percent frequency of occurrence was A comprehensive collection of all recorded for dominant "understory" visible algal species (" general algae") macroalgae (Chondrus crispus, Phyllophora was made in conjunction with destructive spp. and Pellota serrata), as well as sampling in each station area. In counts of Modlolus modlolus, Strongylo-J - addition, collections were taken from the controtus droabachlensis and all kelp a mean low water and mean sea level areas species. (including tide pools) in the intertidal I zone. Information on recruitment of sessile ! benthic organisms and their patterns of Beginning in 1982, two intertidal succession was obtained from the bottom stations (B1MSL and B5HSL, Figure 6-1) panels program. Beginning in 1981, were evaluated nondestructively during bluestone panels (60 cm x 60 cm) were April, July and December. Observations placed 0.5 m of f the bottom substrate at were made at permanent 0.25-m8 quadrats Stations B19 and B31. Stations B04 and at three tidal levels: bare rock zone B34 were added in 1986. Triannual panels (approximate mean high water), predomi- were exposed for 4-month intervals and nately Fucus spp.-covered zone (mean sea collected in April, August and December. J level), and Chondrus crispus-covered zone Long-term panels were exposed for one year j (approximate mean low water). The percent and collected in August. cover of fuccid algae and percent frequen- j cy of occurrence for an established spe-clos list of perennial and annual algal 6.2.2 Laboratory Methods ) species, gastropods (Acmana testudinalls, Littorina spp., Nucella lapillus), Balanus All subtidal and intertidal destructive sp. , and Mytilidae were recorded. General bamples were washed over a 1.0-mm sieve. observations for the entire sampling area All algal species from each sample were were recorded and photographs were taken identified to lowest practical taxon, of each tidal zone and each permanent dried for 24 hours at 105'C, and weighed, 0.25-m 8 quadrat. The frequency of For macrof aunal analysis of the May and i November sampling periods, only fauna 6-2
l MARINE MACROBENTHOS i designated as selected species were A predetermined number of individuals from ) identified and ' counted. The selected each station from May, August, and i species were determined from previous November samples was measured to the studies to be those taxa that are the most nearest 0.1 mm and enumerated. The sex useful as indicators of overall community of the amphipods was identified and I type in the study area based on abundance, presence of eggs or brood was recorded. l trophic level, and habitat specificity. All faunal species collected during Auguat Macroalgae from the general collections were identified to the lowest possible were identified to the lowest possible taxon; non-colonial species were counted taxon. The complete macroalgae species and colonial taxa were listed as present. list was compiled from both general and In addition, spirorbid polychaetes at destructive collections and included crus-subtidal Stations B19 and B31 were tose coralline algae collected only in estimated from five subsamples of the alga August. Phyllophora spp. All undisturbed bottom panel faces were Life history information was collected first analyzed for Balanus sp. and for nine macrof aunal species at the paired Spirorbidae and then scraped to remove nearfield and farfield stations where they sessile bivalves and solitary chordates were most abundant. These were: for identification and enumeration. j Hydrozoa, Bryozoa and any abundant algal ' Taxon Stations species were analyzed only from long-term panels. Molluscs l Hytilidae B1MLW, B5MLW, B17, B35, B19, B31 6.2.3 Analytical Methods l Nucella lapillus B1HLW, B5MLW 6.2.3.1 Community l Amphipods Ampichoc rubricata B1MLW, B5MLW Macroalgal and macrofaunal community Jassa marmorata B17, B35, analyses included numerical classification Pontogenela and analysis of variance of community ) Innrels B19, B31 parameters from August samples including number of taxa and total abundance or l Decapods biomass (Table 6-1). In addition, the Cancor Irroratus B17, B35 median percent frequencies of dominants Cancer borealls B17, B35 in the intertidal non-destructive program during the operational period were com-Echinoderms pared to the median and range from the Strongylocantrocus preoperational period. The total number droebachlensis B19, B31 of algal taxa from the general collections Aster 11dae B17, B35 during 1991 and 1992 was qualitatively compared to the median and range from the 6-3
TiBIE 6-1. SEIECTED BENIHIC TAXA AND PARAMETERS USED IN ANOVA OR WIILCION'S SUMMED RANKS TEST. SEABROOK OPERATIONAL REPORT,1992. DATES USED DATA SOURCE OF COHNUNITY PARAMETER /TAION LIFESTAGE* STATIONS IN ANALYSIS CHA R A f7 ERISTICS6 YARIATION* - Benthic Imminaria saccharina -- B17 1978-1992 Mean number per Preop-Op macroalgae Laminaria digicata -- B35; 1982-1992 sample period and 11 aria esculanca -- B19, B31 1978-1992 station, no trans- ! Agarus cribrosum -- B19, B31 (except 1990) formation. Wilcox-on's sumused ranks by station Choadras crispus -- B17. B19, B31 1981-1992 Mean i frequency per Preop-Op Pbr11opbora spp. -- B35 1982-1992 year. No transfor-Pciloca serraca -- (arcept 1990) mation. Wilcozon's summed ranks test.
, Chondrus crispus -- B17, B1MLW 1978-1992 Biomass per sample Proop-Op, Station, e B5MIK , 835 1982-1992 period and replicate. Year Month & (except 1990) Square root transfor-nation, shallow sub-tidal; no transfor-mation, intertidal Number of taxa -- B1MIM, B17 Aug. 1978 *92 Amount per station. Proop-Op Station Total biomass -- B19, B31 year and replicate; Year B5MLW, 835 1982-1992 no transformation B13, 304 1978-1984, 1986-1992 -
B34 1979-1984, 1986-1992 Ascopbrilus nodosus -- BIMSL, B5MSL 1983-1992 Mean % frequency per Preop-Op i Fucus rasiculosis +- (except 1990) sample period and Fucus distichus year; no transforma-spp. edancatus -- tion. W11cozon's Fucus discichus summed ranks test by spp discichus -- station Fucus sp. -- (continued) .1
TABLE 6-1. (Continued) DATES USED DATA SOCRG OF Cot & UNITY PARAMETER /TAION LIIISTACE* STATIONS IN ANALYSIS CHARACTERISTICS b VARIATION
- Benthic Macrof auna Japirboe rubricata, J/A B1MIM, 1978-89, 91-92 Abundance per Preop-Op. Station, r Nucella lapillus. J/A B5MIM 1982-89, 91-92 replicate; Year, henth Mytilidae spat J/A 3 dates per year Jassa marmorata, J/A B17, 1978-89, 91-92 Mytilidae spat, J/A B35 1982-89, 91-92 Asteriidae J/A B17, 1981-89, 91-92 B35 1982-89, 91-92 Poncogeneia inermis. J/A B19,B31 1978-89, 91-92 Mytilidae spat, J/A Strongylocearrorus J/A T'
w droebschiensis Total density -- B1MIM, B5MIM; August. Amount per year, sta- Proop-Op. Station, 317. B35; 1978-1992 tion and replicate Year B19, B31, B16; (see algte B04, B34, B13 for years) Number of taxa -- Same as above Same as above Number per year. Proop-Op, Station, station, and repli- Year cate; no transforma-tion Hodfolus modiolus J/A B19, 831 1980-1989 Mean per sample Preop-Op 1991-1992 period, Vilcozon's summed ranks test, No transformation E
- Life Stages: J/A = juvenile / adult.
" logg ,(x+1) transformation unless otherwise stated.
" Preop-Op: Operational period (1991-1992) vs. previous years.
MARINE MACRODENTH0S preoperational period. A comparison of well as the operational mean and 1992 community composition of the operational annual mean are presented for each so-and preoperational periods (macroalgae and lected species by station. macrofauna) was carried out using numer-ical classification (Boesch 1977). Bray-Curtis similarity values were computed for 6.3 RESULTS the annual August log-transformed average density (macrofauna) and square-root 6.3.1 Marine Macroalnae t rans formed average biomass (macroalgae) . All macroalgal species with a frequency- 6.3.1.1 Horizontal Ledre Communities of occurrence of less than 1.2% and all macrofauna species occurring less than Number of Taxa 7.6% were excluded from the analysis. Thirty-four algal species and 83 fauna The number of taxa is an important species were included in the numerical measure of community diversity. Macro-classification. The group average method algal taxa richness is measured two ways. (Boesch 1977) was used to classify the Although a qualitative measure, the number samples into groups. of taxa from the general collections represents the maximum number occurring at a station during a given season, 6.2.3.2 Eglected Snecies depending on the visibility and other factors affecting collection efficiency. Comparisons between preoperational and The number of taxa collected from destruc-operational periods were made using tive samples represents a quantitative Analysis of Variance ( ANOVA)(SAS 1985) or measure in a 1/16 m2 area, and thus can the Wilcoxon's summed ranks test (Sokal be statistically tested. and Rolf 1969) for the dominant species listed in Table 6-1. ANOVA was used to test for operational differences in Number of Taxa: General Co11g.ctions abundance or biomass at nearfield/farfield station pairs. The Least Squares Means A total of 128 taxa has been collected test (SAS 1985) was used to evaluate during the preoperational study from 1978 differences when the Preop-Op X Station through 1989 in general collections (NAI . interaction term was significant at a $ 1990). No new taxa were collected in 0.05. The Wilcoxon's test was used to 1990, 1991 or 1992. Historically, test for significant dif ferences between (through 1989) over half (51%) of these preoperational and operational periods in taxa were red algae (Rhodophyta), with the percent frequencies or numbers at each remainder divided almost evenly.between station. For specifics on the ANOVA de- brown algae (Phaeophyta, 27%) and green sign refer to NAI (1992a). In order to algae (Chlorophyta, 22%). This proportion facilitate interpretation of ANOVA re- is typical'for the New Hampshire coast sults, the preoperational mean abundance (Mathieson and Hehre 1986). In 1991 and or biomass and 95% confidence limits as 1992, the proportions were similar to 6-6
MARINE MACROBENTHOS l l previous years. In 1992, more than half similar between corresponding nearfield of the species were red algae (56%), more and farfield shallow subtidal and deep than one quarter brown algae (27%), and stations during both the preoperational , the remainder (17%) were green algae (NAI and operational periods. In the inter- l 1993). tidal zone, the nearfield station (B1MLW) had fewer taxa at the approximate mean low ; Numbers of taxa from general collections water mark and a greater number of taxa in 1991 and 1992 were within the range of at mean sea level than its farfield j previous years at eight of the twelve counterpart at Rye Ledge (B5MLW), a trend ; stations (Figure 6-2). In 1992, numbers that continued from 1990 to 1992 (Figure j of taxa at most of these stations in- 6-2, NAI 1992a). In the mid-depth zone, creased over low values recorded in 1990 fewer taxa have been recorded throughout and 1991. The number of taxa at B16 in the study at the intake station (B16) than 1992 was lower than the lowest value at the discharge and farfield stations recorded during the preoperational period, (B19 and B31). This may be due in part continuing a trend first observed in 1989 to fewer annual collections at B16 (once l (NAI 1990) . At deep Stations B13 and B34, per year) than at B19 and B31 (three times l the number of taxa in 1992 was the lowest per year). J ever recorded, i Spatini differences remained relatively Number of Taxa: Ouentitative Samoles consistent between the preoperational and ; operational periods. In 1991 and 1992, Numbers of taxa from August quantitative l numbers of taxa were highest at the samples collected at shallow subtidal, I f arfield intertidal mean low water (MLW) mid-depth and deep stations during the and both shallow subtidal stations, operational period were not significantly Lowest numbers of taxa were found at the different from the preoperational period deep stations and farfield high intertidal (Tables 6-2,6-3). In 1992, numbers of mean sea level (MSL) station. During the taxa at most of the nearfield stations in preoperational period, the number of taxa these depth zones (B1MLW, B17, B16, B19, was highest in the intertidal MLW zone, and B04) were within the 95% confidence and generally decreased with increasing limits of the preoperational mean (Table depth (Figure 6-2). This pattern was 6-2). Numbers of taxa at the farfield consistent with other New Hampshire stations (B5MLW, B35, B31, B34) in 1992 studies (Mathieson et al. 1981). De- were lower than the preoperar.ional average clining numbers of taxa beginning in 1989 and outside of the 95% confidence limits. at most of the stations (NAI 1990) have Collections at both intertidal (MLW) sta-made spatial differences less obvious. tions had significantly lower numbers of taxa during the operational period when Nearfield/farfield differences in compared to previous years (Tables 6-2, numbers of taxa from general collections 6-3), as was first noted in 1990. How-in 1991 and 1992 followed previously- ever, numbers of taxa at intertidal observed trends. The numbers of taxa were stations in 1992 increased from the lower-6-7
65 - ! o Median 1 a 1991 33 0 1992 l e August Only 50 - 0 45 - , o y 40 - !! < b a 35 - 5 a X
;c 30 -
O () 25 - o y e 20 - o o o 9 O A o 15 - 11 O O 10 - 5 -i i i i
, i i i i e e i*
B1MSL BIMSL BIMLW BJMLW B17 B35 816
- B19 B31 Bl3
- B04
- B34 SilALLOW MID DEPTil DEEP INTERTIDAL STATIONS Figure 6 2. Preoperational(tluough 1989) median and range and 1991 and 1992 values of number of taxa collected in triannual general algae collecdons at Stations BlMSL, BIMLW, 1 B 17, B 19, B31 (1978 1992), B5MSL, B5MLW, B35 (198'2 1992), and annual collections at B 16 (1980-1984; 1986 1992), B 13, B04 (1978 1984; 1986 1992) and
- B34 (1979-1984; 1986-1992). Seabrook Operational Report,1992.. 6-8
- . . - . .-. - - - = . --
4 TABLE 6-2. PREOPERATIONAL MEAN AND 95% CONFIDENCE LIMITS AND 1992 AND OPERATIONAL MF.AN NUMBER OF TAXA, TOTAL BIOMASS, AND CEONDRUS CRISPUS BIOMASS COLLECTED AT INTERTIDAL, SHALLOW SUBTIDAL, MID-DEPTH, AND DEEP BENTHIC STATIONS. SEABROOX OPERATIONAL REPORT, 1992. PREOPERATIONALC 1992 OPERATIONAld LOWER UPPER PAPJufETER/ TAXON DEPTH ZONE STATIONS CL i CL i i Number of taxa
- 2 Intertidal B1MLV 9.8 10.9 12.0 10.2 9.7 (no. per 1/16 m ) B5MLW 16.4 17.9 19.4 16.0 14.5 t
. Shallow subtidal B17 10.7 11.3 11.9 10.8 10.7 i B35 14.2 15.2 16.2 9.6 12.3 Mid-depth B19 9.7 10.1 10.6 10.2 9.2 B31 10.6 11.0 11.4 8.6 10.3 B16 8.6 9.0 9.4 8.8 8.9 Deep B04 7.3 7.6 7.9 7.4 7.3 :' B13 7.6 7.9 8.2 7.4 7.5 2 B34 7.3 7.7 8.0 6.8 7.4 > Intertidal B1MLV 1030.3 1300.5 1570.7 1046.4 1038.5 Totaj) (g/m biomass
- B5MLV 923.1 1198.0 1472.9 1136.1 1049.0 Shallow subtidal B17 1109.5 1208.4 1307.3 1037.9 1210.5 B35 961.0 1170.0 1378.9 906.1 1101.1 Mid-depth B19 258.1 308.6 359.2 291.3 390.0 B31 388.9 471.2 553.4 444.8 371.8 B16 611.5 779.8 948.1 419.0 536.5 Deep B04 79.5 99.7 119.8 90.7 82.8 l B13 75.4 96.0 116.7 52.3 105.9 i i B34 35.0 71.4 107.7 23.0 29.8 ;
b ' Intertidal B1MLW 749.3 908.7 106.3.1 1130.8 1007.4 Chong)rus (g/m crispus B5MLW 610.6 787.8 965.0 602.4 645.7 Shallow subtidal B17 566.7 644.1 72).5 582.9 579.0 B35 433.9 477.3 520.8 379.3 358.7 Mid-depth B19 0.2 1.4 2.6 1.4 1.3 B31 74.1 99.9 125.8 175.6 104.6
- August only.
Driannual samples, intertidal, shallow and mid-depth subtidal only. Rarely collected at deep stations.
*Preoperational, 1978-1989 period (Stations B1MLW, B17, B19, B31: 1978-1989; Stations B5MLW, B35: .1982-1989; Station B16: 1980-1984, 1986-1989; Stations B13, B04: 1978-1984, 1986-1989; B34 1979-1984, 1986-1989). Mean of annual means.
%er:ationalperiod, 1990-1992.
, TABLE 6-3. RESULTS OF ANALYSIS CF YARIANCE OF NUMBER OF TAIA (per 1/16z a ) AND TCTAL BIOttASS (g per za ) OF NaranAffAF CGLIZCTED IN AUGUST AT INTERTIDAL, mr.rnil SUBTIDAL, AND DEEP STATION PAIRS, 1978-1992. SEABROOK OPERATIONAL REPORT, 1992. PARAMETER DEPTH IONE SOURCE OF VARIATION df SS I* MULTIFIE COMPARISONS' (STATION) (Ranked in decreasing order) 1 14.6 5.56* Op<freop Number of Taxa Intertidal Proopg* 119.7 45.72*** BIMiksLir!IM (B1MLW, 85MLV) Station 1 Year (Preop-Op)* . 13 235.7 6.93** Station I Preop-Op* 1 1.1 0.42 MS Error 9 23.6 Shallow Preop-Op 1 10.2 4.88 NS Subtidal Station 1 26.3 12.62** B35>B17 (B17, 835) Yeer (Preop-Op) 13 63.3 2.34 NS S Station I Preop-Op 1 3.2 1.53 NS
$ Error 9 18.7 o 2.98 NS liid-depth Proop-Op 1 2.5 (B16, B19, 831) Station 2 15.2 6.97**
Year _ (Preop-Op) 13 29.4 2.07* Station X Preop-Op 2 1.0 0.45 NS Error 23 25.1 Deep . Preop-Op 1 0.8 2.98 NS (504, 834, B13) Station 2 0.4 0.67 NS Year (Preop-Op) 12 10.9 3.34** Station X Preop-Op 2 ~ 0.1 0.18 NS Error 23 6.3
TABM 6-3. (Continued) PARfMETER DEPTH ZONE SOURCE OF VARIATION df SS F* MULTIPE COMP &RISONS' (STATION) (Ranked in decreasing order) Total Blomans Intertidal Proop 1 232,551.8 2.87 NS (B1 MIX B5 MIX) Station 1 456,483.5 5.63* B1 Pre 85 Op B1 Op B5 Pre Year (Preop) 13 13,725,239.3 13.03*** Station I Preop 1 524,864.0 6.48* Error 109 8,830,655.8 Shallow Preop 1 33,159.5 0.40 NS Subtidal Station 1 89,681.1 1.09 NS (B17, 835) Year (Preop) 13 2.941,589.3 2.76** Station I Preop 1 43,322.3 0.53 HS 7 Error 109 8.942,826.4 N Mid-depth Preop 1 259,312.1 6.64* (B16, Bis, B31) Station 2 2,356,413.6 30.17*** B16 Pre B16 Op B31 Pro B19 Op 331 Op B19 Pre Year (Preop) 13 1,699,264.1 3,35*** Station I Preop 2 602,530.1 7.71*** Error 186 7,263,473.9 Deep Preop 1 8.589.2 3.90* (804, B34. B13) Station 2 68,021.0 15.42*** B13 Op B04 Pre B13 Pre 504 Op B34 Pre 534 Op Year (Preop) 12 66,553.3 2.52** Station I Preop 2 14,505.9 3.29* Error 187 412,336.2
- Preop-Op = 1990, 1991 and 1992 vs. preoperational (1978-1989) period 'Onderlining indicates no significant difference (a 5 05) 5tations within depth zone among least squares means with a paired c test.
*d Tear within preoperational and operational periods regardless of area Interaction between main effects
*NS = Not significant (p>0.05)
* = Significant (0.051p>0.01)
** = Highly significant (0.012p>.001)
*** = Very highly significant (pi.001)
MARINE MACROBENTHOS than-average levels reported in 1991 (NAI in 1984 (NAI 1985). Total biomass has 1992a), to levels that approached the steadily decreased at this station be-preoperational mean. ginning in 1990 (NAI 1992a; Table 6-2). Total biomass, however, at nearfield Station B19 and farfield Station B31 Total Biomass during the operational period was not significantly different from previous Total algal biomass showed distinct years (Table 6-3),
- changes with depth. During the opera-tional period (1990-1992), August total At the deep stations,1992 total biomass biomass values have been highest in the values were similar to the preoperational intertidal and shallow subtidal areas, and mean at nearfield Station B04, but much lowest at deep stations, consistent with lower than the preoperational average (and previous years (Table 6-2). However, in outside the 95% confidence intervals) at -
the intertidal zone, total biomass was nearfield Station B13 and farfield Stat' ion significantly lower during the operational B34 (Table 6-2) . ANOVA results revealed period at the nearfield station, whereas that total biomass was significantly lower biomass at the f arfield station during the during the operational period at farfield operational period was not significantly Station B34 than during the preoperational different from previous years (Table 6-3). period. At nearfield Stations B04 and Total biomass values in 1991 and 1992 in- B13, there was no significant difference creased over the low values noted in 1990 between operational and preoperational and were within the 95% confidence mean biomass levels (Table 6-3). Intervals of the preoperational period (Table 6-2, NAI 1991b). Community Analysis Total biomass at the shallow subtidal stations showed no significant changes The focus of the multivariate community during the operational period when com- analysis was to determine if plant pared to previous years. In 1992, biomass operation had caused changes in the values were lower than the preoperational species ' assemblages typically found in average but within the range of previous each depth zone. The algal community years (Table 6-2). This difference was during the operational period (1990,1991 not statistically significant. and 1992) was judged to be similar to , previous years if 1990,1991 and 1992 col- ! Changes in total biomass in the mid- 1ections at a given station were placed depth zone were not consistent among with the majority of collections from the l stations (Tables 6-2, 6-3). Total biomass preoperational period. This was true in l was significantly lower during the opera- all cases. tional period than during the preopera-tional period at Station B16. Total In the intertidal zone (HLV, mean low 2 biomass in 1992 (419 g/m ) was still higher water), the habitat at nearfield Station j than the lowest value of 368 g/m2 reported B1 was mostly algae-covered ledge with a 6-12
HARINE MACROBENTHOS small proportion of blue mussel (mytilid) boulders and horse mussel (#odfolus bads. The f ar f'ie ld station (BS) was medlolus) beds. Its farfield counterpart, similar, except for the presence of B31, lacked boulders, was predominately boulders, and its more protected condition algae-covered lodge and horse mussel beds (NAI 1990). The intertidal algae communi- with a small amount of cobble. Substrate ty has been stable at both nearfield and at the nearfield Station B16 (intake) was f arfield areas (B1MLW and B5MLW) since the more similar to the nearfield shallow study's beginning (Figure 6-3, Table 6-4) . subtidal station without boulders or Chondrus crispus was the overwhelming cobble. The mid-depth area has been dominant, and.#astocarpus stellatus was characterized by a predominance of a secondary dominant during both the Phy11ophora spp., and decreased amounts operational and preoperational periods at of Chondrus crispus in comparison to more both stations. C. crispus biomass was shallow communities. Secondary dominants lower during the operational period in have historically dif ferentiated the three comparison to the preoperational mean mid-depth stations. (Table 6-4), but includes the excep-tionally low values recorded in 1990 (NAI The intake station (B16) has been 1991b). characterized by Phy11ophora spp. , along uith Phycodrys rubens as a secondary The habitat at both shallow (4.6 m) dominant (Table 6-4). Moderate amounts subtidal stations (B17, B35) was predomi- of three traditionally shallow-subtidal nantly algae-covered ledge, and a small species (Cystoclonfun purpureum, Ceraslun portion of crustose algae-covered ledge, rubrum and Chondrus crispus) differentiate Boulders were present at the farfield sta- this station from the nearfield discharge tion (B35). At nearfield and farfield (B19) and farfield (B31) stations. Mean shallow subtidal stations (B17 and B35), biomass of all dominants at B16 during the community composition was similar between operational period was lower than during the operational and preoperational the preoperational period (Table 6-4), periods. Chondrus crispus was also the paralleling the trend in the total biomass i dominant species at this depth, with (Tables 6-2, 6-3). Phy11ophora spp. the second-most abundant species, both during preoperational and Phy11ophora spp. also predominated at , operational periods (Table 6-4). C. the discharge station B19, along with crispus biomass was lower during the Phycodrys rubens (Table 6-4). Community operational period than during the composition during the operational period preoperational period at both stations was similar to previous years, and mean (see also section 6.3.1.2), while Phyllo- biomass values during the operational phora spp. biomass was higher during the period were generally within the 957. operational period, confidence limits of the preoperational l period. However, P. rubens biomass during In the mid-depth area (9-12 m), the the operational period was three times habitat at nearfield Station B19 (dis- higher than during the preoperational charge) included algae-covered ledge, period. 6-13
. . ~ .
.t I i
. .... . within group
$nin11AfMy , i f v:t ; y; '
y: 4 Ofsii $N!, ,+.I o 'Tj ~ Q % Q. V ."., )J h,, i number of d's.tsMrMbO_.yjl&
- ";.m- 8e;p Intertidal
~
.w i urnples
_ w a..:t@ g y!n o- +Y M t - d :1 w , '$ s is?M@"s ? fl to::0 g).;:g: - ' g %@sy&prn
- i. . . . . .. . . .. betw een s mup rmygff.. jg);:g'g:{:N. i'
. . . . . .fp? s, -* f;w nrndanty _
1
~ 10 number of wg;WMyu;Qt-samples J"2+h.M?.%
- E"J:
W O*nufegy:t l
-0 mv Shallow s@ . .M ;i:N.sp nifs.1 c t a.q Subtidal t'x$h :Wct fjMl, . St<'5> v?)
Jr J l StId depth g 13:; q-
,/ 'Y Intake
@A s ^.W
+ > 511d dep;h j@M, @u, ( jf Discharge
- a. < x 3:
>s s;p,3 M, . .s 3' . k N b S Mid ' ';5N;O depth W&c j;M' Farfleid s af am;m:. p wi ..w 1, 19 t < 'J > +
,s
[s<',s ; , , y .3, 2 "J Deep intake
] <* , ^s 4
*pP
& s r!:,d.g.::.> . ?!W f. ,f * ,
l ' y' f]f.;f.jfrW. l y_y-q:Qj%yw?}
, %d n' heI.'* 4 0 Deep Discharge s e ed q .- y. e =
W . hy M eetY E by, .: N M /Farfleid w *.:f.Ovp ,
- pt{ny4+Rhi bdfi',
3 t . 7, s 4'N$h5h:.n*
;Qi-> 44W h [t:b v[% TJN:> 4T d[
b I I 8 l
' l 8 l
4 I 3 I I 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 IIR AY.CURTIS SIStILARITY l Figure 6 3. Dendrogram and station groups formed by numerical classification of August collections of marine benthic algae, 1978 1992. Seabrook Operational Report,1992. l l 6-14 1 1 i e- '"-r't 9t- .t % mw--eeS s- n e.m, - , , - . ,
TABLE 6-4.
SUMMARY
OF SPATIAL ASSOCIATIONS IDENTIFIED FROM NUMERICAL CLASSIFICATION (1978-1992) 0F BENTHIC MACROALGAE SAMPLES COLLECTED IN AUGUST. SEABROOK OPERATIONAL REPORT, 1992. WITHIN/ GROUP BIOMASS (g/m2 ) MEAN BETWEEN DEPTH STA- DEPTH YEARS GROUP PREOP
- OP ZONE TIONS (m) INCLUDED SIMILARITY DOMINANT TAXA MEANb CI b MEAN Intertidal BIMLV MLW 1978-1991 .69/.32 Chondrus crispus 986.18 189.73 751.57 B5MLW MLV 1982-1992 Mastocarpus stellatus 215.23 108.66 260.44 Corallina officinalis 51.25 31.30 26.50 Shallow B17 4.6 1978-1992 .76/.55 Choudrus crispus 774.22 111.65 614.88 Subtidal B35 1982-1992 Phy11ophora spp. 204.73 61.90 280.81 i Ceracium rubrum 69.29 20.72 68.49 U Cystocloniuc purpureum 56.59 41.12 102.93 i Corallina officinalis 51.58 23.24 36.69 Mid-depth B16 9.4 1980-1984; .79/.68 Pby11ophora spp. 404.45 99.80 298.42 Intake 1986-1992 Phycodrys rubens 188.86 71.00 132.79 Chondrus crispus 56.97 30.43 6.97 Cystoclonium purpureum 44.50 26.48 39.81 i Ceramium rubrum 34.99 20.70 14.46 Callophyllis cristata 32.46 8.64 28.84 (continued)
L
4 TABLE 6-4. (Continued) WITHIN/ GROUP BIOMASS (g/me ) HEAN BETWEEN DEPTH STA- DEPTH YEARS GROUP PREOP * - OPC ZONE TIONS (m) INCLUDED SIH11ARITY DOMINANT TAXA MEAN CI b MEAN Mid-depth B19 12.2 1978-1992 .77/.68 Phy11ophora spp. 201.85 38.26 219.22 Discharge Chondrus crispus 1.61 1.63 0.19 Phycodtys rubens 50.16 19.30 118.60 Corallina officinalis 15.17 4.41 6.31 Callophyllis cristata 12.52 5.71 16.12 Ptilota serrata 16.01 6.33 11.97 Cystoclonium purpureun 5.97 4.42 _10.27 [ Mid-depth B31 9.4 1978-1992 .79/.64 Phy11ophora spp. 213.17 64.66 161.42 m Farfield Corallina officinalis 97.77 26.70 94.14 Chondrus crispus 114.80 42 26 10.67 Phycodrys rubens 22.93 5.49 27.56 Deep Intake B13 18.3 1978-1984; .69/.54 Phy11ophora spp. 68.85 23.77 86.14 1986-1992 Ptilota serrara 11.54 3.96 8.82 Phycodrys rubens 5.82 2.95 6.19 Deep Dis- B04 18.9- 1978-1984- .66/.54 Ptilota serrata 64.00 18.27 40.50 charge / 21.0 1986-1992 Phy11ophora spp. 10.97 5.04 7.72 Farfield B34 1979-1984; Corallina officinalis 6.86 3.59 1.65 1986-1992
" Preop = preoperational, 1978-1989 period (Stations B1MLW, B17, B19, B31: 1978-1989; Stations B5MLV, B35: 1982-1989; Station B16: 1980-1984, 1986-1989; Stations B13, B04: 1978-1984, 1986-1989; B34: 1979-1984, 1986-1989)
Nean and 95% confidence interval-
*Op= 1990, 1991 and 1992
, . ~ -
1 I MARINE MACROBENTHOS Community composition at the farfield (x = 57.95 g/m*) were similar to previous mid-depth station'(B31), while similar to years (NAI 1991a, 1992b, 1993). other mid-depth stations, was distinct (Table 6-4). Although Phy11ophora spp. Despite its 18-m depth, the algal as-was the most abundant taxon, as at the semblage at the deep intake Station B13 other mid-depth stations, moderate amounts historically was composed mainly of the of Corallina officina11s and Chondrus mid-depth species Phyllophora sp. (Table crispus, and low amounts of Phycodrys 6-4). The presence of moderate amounts rubens distinguished this area from its of the typically-deep species Ptllota nearfield counterpart. Community composi- serrata suggests it is a transition. zone tion at B31 f rcm 1990 to 1992 was similar between mid-depth and deep areas. This to a11 previous years, indicating that the trend continued during the operational species assemblage here shows little year- period, with no change in community to-year variability. Biomass values composition noted. Blomass values of the during the operational period of all dominants during the operational period dominants except P. rubens were within the were within the 95% confidence limits of 95% confidence limits of the preopera- the average biomass during the preopera-tional mean. tional period. In the deepest area (18-21 m), horse In order to monitor the algal community mussel beds constituted over half of the for new or infrequently-occurring species substrate at all three stations; algae- that might bloom to " nuisance" levels, the covered ledge was generally the next most occurrence of rare taxa was also examined. frequent substrate. Boulders mixed with Twenty-four species out of a total of 128 algae-covered ledge were present at B34 occurred infrequently (less than 1.7% (farfield) and, with cobble at 813 frequency) in the biomass collections from (intake). Neither boulders nor cobble was 1978 to 1989 (Table 6-5). Two taxa present at the discharge Station (B04). appeared more frequently in 1990,1991 and Community composition at nearfield and 1992 than in previous years, Petalonia farfield deep stations (B04 and B34) in fascla and Bonnemaisonia hamifera. Both 1990, 1991 and 1992 was similar to pre- species are typical of the eastern coast vious years (Table 6-4). Ptilota serraca, of the U.S. (Taylor 1952), and have been the dominant species during the preopera- recorded from coastal New Hampshire , tional period, continued to predominate (Mathieson and Hehre 1986). Neither during the operational period. Average species is considered a nuisance organism, P. serrace biomass for the group during and both have occurred only at low levels, the operational period (40.5 g/m") was ap- None of the other rare species have been proximately 60% of the preoperational noted as nuisance species in the coastal average (64.0 g/m2 ). However, reductions environment. Therefore, there is no in P. serrata biomass in 1990, 1991, and apparent threat to the established algae 1992 occurred only at the farfield station community. (x = 23.0 g/m 2); nearfield biomass values 6-17
I MARINE MACROBENTIiOS jI
~l l
TABLE 6-5. A COMPARISON OF SPARSELY OCCURRING MACROALGAE TAXA IN AUGUST 1 BENTIIIC DESTRUCTIVE SAMPLES DURING TliE PREOPERATIONAL PERIOD i (1978-1989) AND THE OPERATIONAL PERIOD (1990,1991 AND -1992). I SEABROOK OPERATIONAL REPORT, 1992. f ( l b j SPARSELY OCCURRING TAXA
- SPARSELY OCCURRING TAXA '
1978-1989 1990-1992 1 Monastroma grevillel x Monostroma oxyspermum x ; Enteromorpha intestinalis x \ Enteromorpha linza x k Enteromorpha pro 11fera x. \ Ectocarpus sillculosus x Giffordia granulosa x j Sphacelaria cirrosa x k Desmarestia viridis x Petalonia fascia Scytosiphon lomentaria x Dumontla contorta x Ceranium deslongchampli x Pilayella littoralis x Plumarla elegans x Polysiphonia denudata x Polysiphonia harveyl x Porphyra minista x Entacladla viridis x Spongonema tomentosum x Cladophora sericea x Spongomorpha spinescens x Bonnemaisonia hamifera . Palmaria palmata x Bryopsis plumosa x Chordarla flagelliformis x Isthmoplea sphaerophora x Eesthesia difformis x "less than 9 occurrences out of 512 samples (1.8%) boccurred three times or less during operational period (2%) 6-18
l I HAR1NE MAC!10BENTH05 Eelos and Understory Soecies In the mid-depth zone (Stations B19, B31), Agarum cribrosum uas the most abun-The macroalgal community is a three- dant kelp species during both the opera- ; tiered system of canopy, understory, and tienal and preoperational periods. Lami-crustose coralline species. Canopy spe- narfs sacchardna was also numerous, but cles are comprised of kelps, which occur only at the f arfield station. AJundances from 4-18 m depth. Laminaria spp. pre- of oost of the kelp species in the mid-dominate from 4-8 m, and are replaced by depth zone showed no change during the Agarum cribrosua f rom 8-18 m (Witman 1987, operational period. Mean abundances of Ojeda and
Dearborn 1989). A similar Agarum cribrosum,
Alaria esculenca and distributional pattern was observed in Laminario saccharina during the opastion-this study. al period were not significantly different from previous years (Table 6-6). Although In the nearfield and farfield shallow the mean abundances for L. saccharina were subtidal zone (Stations B17, B35), Lamin- reduced at both stations in 1992 and dur-aria saccharina was the most numerous kelp ing the operational period when compared species, and L. digicaca was a secondary to the preoperational mean, the reductions dominant during both the preoperational were not statistically significant. L. and operational periods. Numbers of L. diglesca abundances in 1991 and 1992 were saccharina showed strong recovery at significantly reduced at both mid-depth Station B17 in 1992 after an observed stations in comparison to the preopera-decline in the population from 1989 tional period, but the reductions were through 1991 (Table 6-6, NAI 1992a). As most marked at B19. The continuing a result, there was no significant dif- decline at Station B19 is part of an ference in the operational abundance in overall trend which began in 1988 (NAI comparison to the preoperational abun- 1989), and the reduction at Station B31 dance. At the shallow subtidal Station became evident in the spring of 1990 B17, L. digicaca demonstrated a signifi- before plant operation began (NAI 1991b). cant reduction in abundance in 1991 and 1992 when compared to previous years. Kelps are sensitive to storm events This decline began in 1989, prior to plant (Witman 1985). Three of the kelp species, operation (NAI 1989, 1990, 1991b). (Laminarla digitate e t P19, 4. saccharina Although abundances of both kelp species at B17 and B35, Agarum cribrosum at B19 were also reduced at the farfield station and B31) showed substantial reductions in B35 during the operational period, there October 1991, after Hurricane Bob (NAI were no significant differences from the 1992a). Strong bottom currents may have preoperational period (Table 6-6), dislodged the kelps. In 1992, numbers of Substantially-higher abundances of Lacuna kelps increased te levels comparable to vineca, a molluscan predator on kelps, those prior to Hurricane Bob (NAI 1992b, coincided with reduced kelp density in 1993). August 1990, 1991 and 1992 and may have contributed to the observed differences (Section 6.2.2.1; NAI 1991a,1992b,1993). 6-19
TABLE 6-6. PREOPERATIONAL MEAN AND 95% CONFIDENCE LIMITS, 1992 AND OPERATIONAL MEANS, AND RESULTS OF WILCOXON'S SUMMED RANK TEST COMPARING NUMBERS OF FOUR KELP SPECIES AND PERCEhT
, FREQUENCIES OF THREE UNDERSTORY ALGAL TAXA BETWEEN OPERATIONAL AND PREOPERATIONAL PERIODS. SEABROOK OPERATIONAL REPORT, 1992.
PREOPERATIONAL* 1992 OPERATIONALb TAXON STATION LCL i UCL i i df ZC KELPS Laminaria digirata 17 140.6 213.9 287.2 27.0 29.7 1 -3.84*** 35 96.5 155.8 215.1 178.5 136.5 1 -0.24 NS 19 81.5 139.9 198.3 17.5 18.6 1 -3.54*** 31 401.7 500.2 598.7 273.7 249.5 1 -3,49***- Laminaria saccharina 17 270.8 415.1 559.4 403.0 250.3 1 -1.81 NS 35 210.9 325.7 440.5 276.1 242.0 1 -0.83 NS 19 1.9 59.1 116.3 16.7 15.1 1 -1.49 NS 31 59.7 95.5 131.3 80.9 69.4 1 -0.54 NS Alaria esculenta 19 0.0 2.4 7.2 0 4.4 1 0. % t1S 31 19.9 75.2 130.5 125.3 75.0 1 -0.23 NS e 4 Agarum cribrosum 19 613.5 786.6 959.7 702.5 699.7 1 -0.95 NS c) 31 280.2 366.4 452.6 297.1 283.2 1 -1.11 NS EDERSTORY Chondrus crispus 17 67.5 71.8 76.0 72.7 75.5 1 0.83 NS 3.i 46.5 54.1 61.7 66.0 68.1 1 1.96 NS 15 0.4 4.2 7.9 2.0 6.8 1 1.31 NS 31 14.2 21.0 27.8 30.0 26.7 1 2.00* Pby11ophora sp. 17 14.6 20.3 26.0 33.0 25.3 1 0.35 NS 35 11.2 19.9 28.7 41.7 27.4 1 0.39 NS 19 28.5 34.0 39.6 43.3 39.6 1 -0.35 NS 31 25 5 31.8 38.0 31.7 31.3 1 -0.12 NS Ptilota serrata 17 0 0.8 1.6 0 1.4 1 0.52 NS 35 0 0.6 1.1 1.0 0.9 1 0.75 NS 19 28.6- 35.6 42.5 48.3 38.2 1 0.35 NS 31 9.3 13.1 16.8 12.3 10.3 1 -1.54 NS
*Mean of annual means. Years for kelps-Stations 17,19,31: 1978-1989; Station 35: 1982-1989.
For understory species-Stations B17,B19,B31: 1981-1989; Station B35: 1982-1989. LCL, UCL - Upper and lower confidence limits, b l991 and 1992
*NS = not significant (p>0.05)
* = significant (0.052p>0.01)
** = highly significant (0.012p>.001)
T f HARINE MACROBENTH0S Msasurements of percent frequency of dominate in 1992. At nearfield Station occurrence of the three understory algae B1 during the operational period, the that were dominant at transect sites immature perennial Fucus spp. occurred during the preoperational period (Table only during December (Table 6-7). The 75% 6-6) showed dif ferences among depths that frequency of occurrence for 1992 was much were similar to those observed from greater than the preoperational median biomass collections (Table 6-4). The (6%) but within the preoperational range. understory community in the shallow zone Historically, the percent frequency of historically has been dominated by Chon- occurrence of Fucus spp. at farfield drus crispus with Phyllophora spp. a Station B5 has been greater than at secondary dominant, while the mid-depth Station B1 during all three sample community was dominated by Phy11ophora periods. This pattern has continued spp. A similar pattern occurred during during the operational years. The annual the operational period. Algal frequencies green algal species complex Urospora of C. crispus, Phyllophora spp., and penicilliformis/Ulothrix flacca occurred Ptilota serraca during 1991 and 1992 at at both stations only during the spring both nearfield stations were not signifi- in 1992. At the nearfield Station B1, the cantly different from those observed frequency of occurrence in the spring of historically (Table 6-6). C. crispus 1992 was similar to previous years. At showed a significant increase during the farfield Station B5 during 1992 and the operational period that occurred only at operational period, the complex U. farfield Station B31 (Table 6-6). Phyllo- penicillifornis/U. flacca was reduced when phora spp, has shown a trend of increasing compared to the preoperational median, but abundance during the operational period within the established range. Historical-at both shallow subtidal stations, but ly, occurrence of this complex at Station this trend was not significant. B5 has been greater than the range for Station Bl. However, during 1992, the frequency of occurrence at Station B5 was Intertidal Communities (Non-Destructive less than B1 (Table 6-7). tLonitorine Program) The Fucoid Ledge Site, in the mid-tide In situ counts of macroalgae at the zone, is situated in the area of maximum nearfield and farfield intertidal stations fuccid algae cover. In 1992, the peren-(B1 and BS) monitor quadrats in fixed nial Tucus spp. was the dominant taxon locations, thus eliminating small-scale within the quadrats at Stations B1 and B5, spatial variability and focusing on as has been true in previous years (Table temporal variation. The Bare Ledge Site, 6-7). Median percent cover and percent at the upper edge of the mid-tidal zone, frequency during 1992 and the operational was characteristic of ledge not continu- period were generally within or close to ously covered by macroalgae. Algal the range of the preoperational period, species that have been dominant histori- These fuccids were persistent and occurred cally at the bare ledge site continued to frequently, although relatively low cove-6-21
i l TABLE 6-7. PERCENT COVER AND PERCENT FREQUENCY OF DOMINANT PERENNIAL AND ANNUAL HACROALCAL SPECIES PER 0.25 m AT FIXED INTERTIDAL NON-DESTRUCTIVE SITES DURING THE PREOPERATIONAL AND OPERATIONAL PERIOD. SEABROOK OPERATIONAL REPORT, 1992. ZONE */ SPECIES STATION PERIODd APR JUL DEC t Hare Ledee' fucus spp. B1 Preoperational 6 19 6 (range) (0-81) (0-94) (0-94) 1992 0 0 75 Operational 0 0 43.5-B5 Preoperational 82 97 100 (range) (0-100) (12-100) (0-100) 1992 94 81 94 Operational 94 90.5 90.5 Urospora penicilliformis/ B1 Preoperational 45 0 0 Ulochrix flacca (range) (0-99) (0) (0) 1992 55 0 0 Operational 44 0 0 B5 Preoperational 73 0 0 (range) (0-100) (0) (0) 1992 13 0 0 Operational 22 0 0 Fucold Ledgg Fucus spp.* B1 Preoperational 93 93 68 (range) (25-98) (60-100) (25-95) 1992 95 98 48 Operational 95 89 63 B5 Preoperational 94- 94 93 (range) (60-98) (65-100) (2-98) 1992 60 85 100 Operational 65.5 86 92.5 Fucus spp.I' B1 Preoperational 94 88 88 (range) (69-100) (75-100) (69-94) 1992 87 81 62 Operational 87 90.5 71.5 B5 Preoperational ' 85 85 91 (range) (62-100) (69-100) (31-100) 1992 75 75 88 Operational 81 87.5 84.5 (continued) l 6-22 i
TABLE 6-7. (Continued) ZONE */ SPECIES STATION PERIOD d APR JUL DEC b Chondrus 22na Chondrus crispus B1 Preoperational 45 34 45 (range) (20-53) (20-38) (28-53) 1992 35 8 25 Operational 46 17 31.5 B5 Preoperational 45 48 41 (range) (0-72) (41-55) (39-48) 1992 38 65 39 Operational 48 63 46 Hastocstpus stellatus B1 Preoperational 47 66 48 (range) (21-69) (65-71) (32-67) 1992 33 42 39 Operational 40 55.5 35 B5 Preoperational 47 51 44 (range) (0-53) (41-63) (43-56)- 1992 42 23 46 Operational 42.5 43 42.5 Corallina officine11s B1 Preoperational 0 0 0 (range) (0) (0) (0) 1992 0 0 0 Operational 0 0 0 B5 Preoperational .30 52 52 ( range) (15-57) (33-61) (31-65) 1992 52 55 69 Operational 59 61.5 '57
- Bare ledge: approximate mean high water. Fucoid ledge: approximate mean sea level.
Chondrus zone: approximate mean low water. b Percent frequency of occurrence based on point contact line sampling (Fucoids: holdfasts only).
- Percent cover of whole plants based on fixed quadrats.
d Preoperational: 1982-1989 median and range ~. Operational median: 1991 and 1992. 1992 annual mean.
'l 6-23
HARINE HACROBENTHOS i rages have been occasionally recorded in The Chondrus zone quadrat in the MIM previous years. (mean low water) zone is situated in the 1 area of maximum red algae cover. In 1992, Coverage of dominant fuccids in the as has been true historically, Chondrus l fucoid zone (measured using fixed-line crispus and #astocarpus stellatus dominat-transects) has shown some change during ed this zone. Overall operational period the operational period. In 1992, in median percent frequencies for both contrast to the preoperational years, species exceeded 30% during most sample. , Ascophyllum nodosum occurred somewhat less periods, with few differences noted be-frequently at Station B5 than at B1 (Table tween the two stations, consistent with 6-8). At nearfield Station B 1, Asco- previous years (Table 6-7). However, phyllum nodosua mean frequency of oc- during 1992, the percent cover of Chondrus currence during the operational period crispus was below the preoperational range overall was significantly greater than the during July and December at nearfield Sta-preoperational mean. The mean frequency tion Bl. At farfield Station B5,1992 and of occurrence of A. nodosum at farfield operational trequencies were higher than Station B5 during the operational years the preoperational range in July. In was not significantly different from pre- addition, #astocarpus stellatus f requency vious years. Fucus vesiculosis in 1992 of occurrence at B1 and B5 during July was continued a trend of decreased frequencies the lowest recorded to date. December at Station B1 that began in 1989, result- frequencies, however, were similar to pre-ing in a significantly lower operational vious years. The understory taxon Coral-mean in comparison to the preoperational lina officinalls occurred only at B5 in mean (Table 6-8). There has also been a 1992 and was absent at B1, consistent with significant but less dramatic reduction previous years. This species occurred in in occurrence of F. vesiculosis at moderate frequencies at B5 in all seasons; farfield Station B5. In 1992, Fucus dist- the 1992 frequencies were similar to ichus ssp. edentatus frequencies substan- previous years. tially increased over low levels recorded in 1991. As a result, the frequency of occurrence during the operational period 6.3.1.2 Selected Soecies showed no significant difference from the preoperational period (Table 6-8, NAI Chondrus erisous 1992a). Fucus distichus ssp. distichus, which did not occur during the preopera- Chondrus crispus (Irish rr.oss), a red tional period, has occurred at both algae, is common to the lower intertidal nearfield and farfield intertidal stations and shallow subtidal habitats from Nova during the operational period. Frequency Scotia to New Jersey (Taylor 1952). It levels diminished in 1992, however, was the dominant understory algal species following moderate values recorded in 1991 in the lower intertidal zone and, to a (NAI 1992a). lesser extent, in the shallow subtidal zone near the Sunk Rocks (see Table 6-4). 6-24
TABLE 6-8. PREOPERATIONAL MEAN AND 95% CONFIDENCE LIMITS, 1992 AND OPERATIONAL MEANS, AND RESULTS OF WILCOXON'S SUMMED RANKS TEST COMPARING PERCENT FREQUENCIES OF FUCOID ALGAE AT TWO FIXED TRANSECT SITES IN THE HEAN SEA LEVEL ZONE BETWEEN THE PPIOPERATIONAL AND OPERATIONAL PERIODS. SEABROOK OPERATIONAL REPORT, 1992. PREOPERATIONAL" TAXA STATION LCL i UCL 1992 OPERATIONALb df Z* X X Ascopby11ue nodosum B1 26.44 32.0 37.56 42.7 41.0 1 2.6** B5 31.10 41.2 49.38 37.0 35.2 1 -1.26 NS Fucus resiculosis B1 25.72 47.4 69.04 0.7 1.3 1 -3.39*** BS 17.27 27.0 36.64 12.7 16.3 1 -1.99* Fucus distichus El 6.02 16.2 26.36 23.3 18.8 1 0.76 NS spp. edentatus B5 0.00 3.6 12.31 16.0 8.0 1 0.90 NS 7 U Fucus distichus B1 -- 0.0 -- 0.7 9.5 1 3.31*** spp. distichus B5 -- 0.0 -- 7.3 5.5 1 3.31*** Fucus sp. B1 0.00 7.6 18.11 23.3 27.8 1 2.72** B5 0.00 0.6 2.13 2.7 6.2 1 3.59***
"Mean of annual means, 1983-1989. LCL, UCL = upper and lower 95% confidence limits.
b l991 and.1992. NS = not significant (p>0.05)
* = significant (0.01<ps0.05) ** = highly significant (0.001<ps.01) *** = very highly significant (ps0.001)
1 4 MARINE MACR 0BENTH05 At the nearfield and farfield intertidal decreases in juvenile Myt111dae (NAI stations , Chondrus crispus biomass during 1991b). the operational period was not signifi-cantly different from values recorded In the intertidal zone, the number of during the preoperational period (Table taxa increased in 1992 at both nearfield 6-9). The trend of decreased biomass at and farfield stations. However, the mean both stations, which began prior to plant number of taxa for the operational period operation, was reversed in 1991. During (1990-92) was significantly below the 1992, C. crispus biomass continued to in- preoperational average at both near- and crease at B1 and stabilized at B5 (Table f arfield stations (Tables 6-10,11) . The 6-2, NAI 1992a). In the shallow subtidal numbers of taxa at both stations were zone, C. crispus biomass levels during the within the range of the preoperational operational period were significantly period (NAI 1991b). The low total mean lower than collections from the pre- densities of 1991 increased during 1992 operational period at both nearfield and and were within the 95% confidence limits farfield stations (Tables 6-2, 6-9). In of the preoperational average at both 1992, C. crispus biomass at intertidal and near- and farfield stations (Table 6-10). l shallow subtidal stations (x = 1091. 25 The total mean density (no. of individu-g/m8 ) recovered af ter substantial reduc- als/m2 ) during the operational period was tions in November (x = 424.72)fo11owing not significantly different from the a severe northeastern storm in 1991 (NAI preoperational density at either station. 1992a, Table 6-2). In the shallow subtidal (4,6 m). zone, the number of taxa at the nearfield 6.3.2 liaring_Jac ro f agan station (B17) increased significantly during the operational period, while the 6.3.2.1 Horizontal Ledge Communities f arfield station (B35) was within the 95% confidence limits of the preoperational t[umher of Tua and Total Density average. The total density at both stations during the operational period was The number of taxa and total density near the preoperational average and no 8 (nwnber of noncolonial macrofauna /m ) have significant dif ferences occurred (Tables been used to monitor spatial and annual 6-10, 6-11). l trends in the macrofaunal community. l These parameters have been measured in In the mid-depth (9-12 m) zone, changes August since 1978, and have shown broad- in number of taxa between the operational scale changes in relation to depth. The and preoperational periods were not number of taxa generally increased from significant at the three mid-depth intertidal through mid-depth stations, and stations (Table 6-11). Changes in total declined slightly at the deep stations. density were significant, with the intake Total density showed a general decrease (B16) having a significantly lower density with increasing depth, mainly due to during the operational period. Likewise, the total biomass of algae was signifi-6-26
2 TABLE 6-9. RESULTS OF ANALYSIS OF VARIANCE OF CEONDRUS CRISPUS BIOMASS (g/m ) AT INTERTIDAL AND SHALLOW SUBTIDAL STATION PAIRS FOR THE PREOPERATIONAL AND OPERATIONAL (1991 AND 1992) PERIODS. SEABROOK OPERATIONAL REPORT, 1992. SOURCE OF PARAMETER DEPTH ZONE VARIATION df SS Ff MULTIPLE COMPARISONS Chondrus Intertidal Preop-Op* 1 125,204.75 1.20 NS B1MLW>B5MLV crispus (B1, B5) Year (Preop-Op)b 12 12,957,037.08 10.32*** Month (Year)* 28 14,820,858.80 5.06*** Stationd 1 4,918,102.86 47.02*** Station X Preop-Op" 1 57,702.30 0.55 NS Error 276 28,867,835.68 h* Shallow Preop-Op 1 236.09 5.97* Op< Preop subtidal Year (Preop-Op) 12 685.21 1.44 NS B17>B35 (B17, B35) Month (Year) 28 4,788.03 4.32*** Station 1 814.36 20.59*** Station X Preop-Op 1 1.00 0.03 NS Error 276 10,916.94
- Preop-Op = 1991 and 1992 vs. all previous years, regardless of station D ear nested within preoperational and operational periods regardless of station
- Month within year regardless of year, station or period d Station pairs within a depth zone: intertidal = B1MLW, B5MLW; shallow subtidal = B17, B35, regardless of year or period
" Interaction of main effects f
NS = Not significant (p>0.05)
* = Significant (0.052p>0.01)
** = Highly significant (0.012p>0.001)
*** = Very highly significant (ps.001)
TABLE 6-10. PREOPERATIONAL MEAN AND 95% CONFIDENCE LIMITS AND 1991, 1992 AND OPERATIONAL MEAN NUMBER OF TAXA (per 1/16m )2 AND GEOMETRIC MEAN DENSITY (No./m2) FOR TOTAL DENSITY (NON-COLONIAL MACROFAUNA) SAMPLED IN AUGUST AT INTERTIDAL, SHALLOW SUBTIDAL,- MID-DEPTH AND DEEP STATIONS. SEABROOK OPERATIONAL REPORT, 1992. PREOPERATIONAL" OPERATIONALb 1211 1992 DEPTH ZONE STATION LOWER MEAN UPPER MEAN MEAN MEAN MEAN NO. OF TAXA (No. per 1/16 m2 ) e Intertidal B1MLW 43 49 55 37 31 41 B5MLW 42 48 55 42 36 43 Shallow subtidal B17 54 58 62 63 62 61 B35 51 55 59 52 52 48 Mid-depth B16 63 70 76 68 73 63 B19 60 68 76 72 64 65 B31 45 51 56 53 46 41 Deep B04 57 63 69 68 73 61
- B13 49 54 59 59 72 43
. O B34 54 64 74 59 64 49 m .
TOTAL DENSITY (No./m** i Intertidal BIMLV 82562 122795 182634 96(24 35089 125429 B5MLW 42577 68684 110798 85019 48270 80734 Shallow subtidal B17 77462 23373 31284 28410 18362 38900 B35 19175 28372 41981 28930 31635 20172 Mid-depth B16 19671 31590 50730 11388 11217 7980 , B19 8559 12785 19097 14803 14044 6833 B31 8090 16240 32681 12418 20868 8592 Deep B04 3568 4936 6828 3957 4676 4119 B13 3291 6073 11205 9671 5517 14165 B34 3119 5523 9780 5127 4031 3874
*Preoperational period extends through 1989 (Stations B1MLW, B17, B19, B31: 1978-1989; Stations B5MLW, B35: 1982-1989; Station B16: 1980-1984, 1986-1989; Stations B13, B04: 1978-1984, 1986-1989; 1
Station B34: 1979-1984, 1986-1989). b Operational period: 1990-1992. _ _ _ - _ _ _ - _ - _ _ . - _ - - _ _ - _ _ _ _ _ _ _ - _ - _=_
-TABLE 6-11. RESULTS OF ANALYSIS OF VARIANCE OF NUMBER OF TAXA (per 1/16 2m ) AND TOTAL DENSITY (per m2 ) OF MACROFAUNA COLLECTED IN AUGUST AT INTERTIDAL, AND SHALLOW, MID-DEPTH, AND DEEP SUBTIDAL STATIONS 1978-1992. SEABROOK OPERATIONAL REPORT, 1992.
STATION MULTIPLE COMPARISONS
- PARAMETER GROUPS CLASS VARIABLE df SS F* (Ranked in decreasing order).
Number of Taxa B1MLW, b Preop-Og 1 1512.39 21.00*** Op< Preop B5MLV Station 1 27.11 0.38 NS Year (Preop-Op) 13 6869.22 7.34 NS Station X Preop-Opd 1 270.14 3.75 NS Error 109 7849.23 b B17, B35 Preop-Og 1 18.14 0.21 NS + Station 1 1046.84 12.40*** Year (Preop-Op) 13 2721.73 2.48** B170P B17 Pre B35 Pre B3500 y Station X Preop-Opd 1 420.91 4.99* g Error 109 9919.10 b B19, B31, Preop-Op 1 74.22 0.57 NS B16 Station 2 9735.38 37.66*** B19 B16 B31 Year (Preop-Op) 13 11668.95 6.94*** Station X Preop-Opd 2 195.92 0.76 NS Error 186 24043.34 B04, B34, h Preop-Op 1 106.18 0.80 NS B13 Station 2 1875.32 7.06*** B04 B34 B13 Year (Preop-Op) 12 13528.15 8.49*** Station X Preop-Opd 2 566.86 2.13 NS Error 187 24839.73 (Continued) 2
TABLE 6-11. (Continued) STATION MULTIPLE COMPARISONS
- PARAMETER GROUPS CLASS VARIABLE df SS F* (Ranked indecreasing order) b Total Density B1MLW, Preop-Op 1 0.003 0.05 NS B5MLW Station 1 0.49 8.05** B1MLW>B5MLW Year (Preop-Op) 13 6.79 8.61***
Station X Preop-Opd 1 0.20 3.24 NS Error 109 6.61 b 0.04 0.69 NS B17, B35 Preop-Op 1 Station 1 0.06 1.11 NS Year (Preop-Op) 13 3.26 4.94*** Station X Preop-Opd 1 0.04 0.80 NS Error 109 5.53 7 B19, B31, Preop-Op b 1 0.92 8.85** B16 Station" 2 0.53 2.55 NS Year (Preop-Op) 13 10.42 7.68*** Station X Preop-Opd 2 1.42 6.80*** B16 Pre B31 Pre B1900 B19 Pre B3100 B160n Error 186 19.42 b 0.03 0.34 NS B04, B34, Preop-Og 1 B13 Station 2 1.42 7.35*** B13 B34 B04 Year (Preop-Op) 12 8.89 7.68*** Station X Preop-Opd 2 0.56 2.90 NS Error 187 18.03 ONS = Not significant (p>0.05)
* = Significant (0.05dp>0.01)
** = Highly significant (0.012p> 001)
O** = Very highly significant (ps.001) b Preoperational-(through 1989) versus operational (1990-1992) period, regardless of station. l l *Nearfield = Stations B1MLV, B17, B19, B16, B04, B13; farfield = Stations B5MLW, B35, B31, B34, regardless i of year / period. d interaction between main effects.
" Underlining signifies no significant differences (a 5 0.05) among least squares means with a paired t-test.
Multiple comparisons listed in decreasing order.
MARINE MACRODENT1105 cantly lower during the operational period B31), and deep (B04, B13, B34) areas were (Table 6-3). The total density of distinct in both species distributions and macrofauna at the intake peaked in 1988 abundances. In most cases, based on the 8 (83,466/m ) and decreased by more than 80% similarity in species composition, the the following year (NAI 1990). By 1992, 1990-1992 (operational) collections were the total density had decreased by an placed in the group with the majority of order-of-magnitude to the lowest ever preoperational collections from the same recorded (Table 6-10; NAI 1991b). Since station (Table 6-12, Figure 6-4). The the decline began in 1988, prior to plant intertidal, shallow subtidal, and mid-operation, it is not an operational depth assemblages showed little year-to-effect. No significant changes in total year variation in their community struc-density occurred at the discharge (B19) ture. Benthic assemblages were less or its f arfield counterpart (B31) (Tables stable at deep stations, especially at l 6-10, 6-11). B13, as evidenced by shifts in group assignment by the cluster analysis. I In the deep (18-21 m) zone, in 1992, the number of taxa decreased from 1991 values Spatial differences in community at all three stations, and the operational structure among depths were indicated by average was near the preoperational differences in densities of dominant taxa average at each station (Table 6-10). The as well as species composition. Mytilidae number of macrofaunal taxa showed no was one of the dominant taxa in all depth significant changes during the operational zones. Less-abundant species, such as period when compared to previous years peracarids Jassa marmorata, Jaera marina, (Table 6-11) . In 1992, total density was gastropod Lacuna vincts, and barnacle within 95% confidence limits of the Balanus crenatus accounted for the majori-preoperational average at B04 and B34. ty of the among-station variability. The total density was above the preopera-tional average at the intake (B13) in The intertidal habitat (Group 1) was the 1992, but well within the range of the most distinct (between group similarity preoperational period (NAI 1991b). of only 0.437) of all groups because of Changes in total density between the the overwhelming predominance of Mytilidae operational and preoperational periods spat (69,205/m 2 preoperationally). Also, were not significant (Table 6-11). the presence of species that are restrict-ed to or most abundant in the intertidal zone (Nucella lapillus, Turtonia minuta, Community Structure Jaera marina) distinguish this group from the deeper water groups (Table 6-12). The noncolonial, macrofaunal, hard- Other dominants included the molluscs bottom community structure at all near- /Ilotella sp. spat and Locuna vinces. and farfield stations has historically Every intertidal collection, including shown changes related to depth (NAI 1992, was placed in Group 1 based on 1991b). Intertidal (B1, B5), shallow similar species composition and abundance. subtidal (B17, B35), mid-depth (B16, B19, During the operational period (1990-1992) 6-31
TABLE 6-12. STATION GROUPS FORMED BY CLUSTER ANALYSIS WITH PREOPERATIONAL AND OPERATIONAL (1990-1992) GEOMETRIC MEAN DENSITY AND 95% CONFIDENCE LIMITS FOR ABUNDANT MACROFAUNAL TAXA (NON-COLONIAL) COLLECTED ANNUALLY IN AUGUST FROM 1978 THROUGH 1992. SEABROOK OPERATIONAL REPORT, 1992.
=
PREOPERATIONAL OPERATIONAL GROUP No./ NAME/ DOMINANT SIMILARITY" STATIONS (YEARS) TAXA LOWER MEAN UPPER n MEAN n 1 Intertidal Mytilidae 47977 69205 99824 20 71595 6
.700/.437 B1 MEW (1978-92) Joera marina 2116 3626 6216 1324 B5MLV (1982-92) Lacuna vincta 2035 3209 5060 3532 Oligochaeta 1203 2030 3423 789 Turtonia minuta 1367 2707 5360 1830 i Riatella sp. 1464 2604 4631 664 u Nucella lapillus 925 1501 2432 1394
" Cammarellus angulosus 181 572 1803 76 Cammarus oceanicus 241 564 1319 1588 Anomia sp. 373 493 650 567 2
Shallow Mytilidae 2905 4758 7793 20 2362 5 subtidal Lacuna vincta 3761 5379 7694 11925
.755/.582 B17 (1978-89, Idotea phosphorea 1695 2166 2768 1753 1991-92) Pontogeneia .rnermis 1248 1773 2518 1262 E35 (1982-92) Jassa marmorata 1097 1572 2254 1665 Canre11a 479 701 1027 S29 s'eptentrionalis Idocea balthica 508 890 1559 1131 Asteriidae 385 602 940 718 Calliopius 402 575 821 734 laeviusculus Ischyrocerus angulpes 316 539 920 381 Fiatella sp. 129 186 270 40 (continued) i
4 TABLE 6-12. (Continued) PREOPERATIONAL OPERATIONAL GROUP NO./ NAME/ DOMINANT SIMILARITY" STATIONS (YEARS) TAXA LOWER MEAN UPPER n MEAN n 3 Mid-Depth: Mytilidae 3582 5791 9363 34 4078 13 Discharge / B19 (1979-92) Pontogeneia inermis 994 1527 2346 702
-Farfield/ B31 (1979-92) Capre11a 642 974 1476 643 Intake / B16 (1980-84, 86-92) septentrionalis Recent Deep B13 (1986-87, 89-92) Anomia sp. 576 798 1105 833 Intake B17 (1990) Elate 11a sp. 521 759 1105 409
.702/.650 Lacuna vincts 276 406 597 493 Balanus crenatus 30 88 251 340 m 4 d, Deep; Pontogencia inermis 211 297 420 27 105 6
') Discharge / B04 (1979-84, 86-92) Asteriidae 185 249 334 290 Farfield/ B13 (1978-84, 88) Anomia sp. 158 247 388 469 Historic B34 (1979, 81-84, Tonicella rubra 132 157 187 73 .. Intake 86-92) Capre11a 99 154 238 93
.665/.650 septentrionalis Mytilidae 107 184 316 124 Musculus niger 70 108 168 104 6 27 111 165 Balanus crenatus Thelepus cincinnatus 8 19 44 185 5
Misc. Pontogeneia inermis 83 817 7986 4 - 0
.638/.607 B19 (1978) Mytilidae 3 148 5052- -
B31 (1978) Capre11a 149 235 369 - B34 (1980) septentrionalis B04 (1978) Elate 11a sp. 19 166 1365 - Lacuna vincta 36 158 670 - Anomia sp. 84 211 528 - Asteriidae 96 221 507 -
*within group /between group similarity
....... oithin group simhsrity _
% Gj?' i@f xx
.Mi 9 number of samples g,
fe
.r-- f$ , ;
; 3 Group 1 Intertidal
...U... between groep similanty I [f[
10 sets - WSF W in number of sa.nples , ,,,;,,
.O WWWe'
%,y,ggs le'<l<lelrl<'<l Group 2 Shallow Subtida!
NN%'N, j E l ! L
- -l l
Group 3 Mid-depth: Discharge /Farfleid/ Intake Deeps intake (recent) Group 4 Deep: Discharge /Farfield/ Illstoric Intake
-v / /// / / / // ///s Group 5 - Miscellaneous
- i i i i i 0.3 0.4 0.5 0.6 0.7 0.8 0.9 BRAY CURTIS SIMILARITY GROUPS / STATIONS a INTERTIDAL SIIALLOW MID-DEFTl! DEEP $
1 l 5 17 l 35 16 l 19 l 31 l 13 4 l 34 3 9 : Group 1
,,,,,,'l'l
+
8h ss dd :d N[#['['l'lN%
@iryN- %'%'
l
- w croup 2 i:Qtt Ak k.%y g
# g'g ##
g g# g% l 87 XsXs,
, i i croup 3
$$e$D 51 4ev m :,l-l-l,l,l-l :
g as ~A*>vNNN% croup 4 8 s3 f dwv wi wWW f' ,: !!hl w Group 5
;[ :
8 hN h, : ; ,l l l DM 88mP led
- 1 MR W 'c ! J
- a E M$ I'b i l 71 ${[!j$
*ikk lk [ i t i :
78 fe2e2e; [////// ! / j ' //j 1 l Figure 6-4. Dendrogram and station groups by year formed by numerical classification of August collections of marine macrofauna, 1978-1992. Seabrook Operational Report,1992. i 6-34
HARINE HACROBENTHOS densities of Joera carina, Elatella sp. , Group 3 (primarily mid-depth stations Cammarellus angulosus and 011gochaeta de- (B19, B31 and B16) and the deep intake creased, whereas Cammarus oceanicus in- station (B13) for most years since 1986) creased. Densities of mytilids and the was the largest group. It was usually j two other most common species essentially characterized by a predominance of , showed no change (Table 6-12). Myt111dae and the amphipods Pontogenela inermis and Capre11a septentrionalis The shallow subtidal habitat (Group 2) (Table 6-12). Stations B31 (farfield), includes Stations B17 and B35 and had the B19 (discharge) and B16 (mid-depth intake) highest within group similarity (Table 6- were characterized by this assemblage 12). Mytilidae was still the predominant every year except 1978. Despite its 18-m taxon, although more than an order-of- depth, Station B13 has been classified in magnitude less abundant than in the the mid-depth macrofaunal assemblage since intertidal area. Aside from the herbivo- 1986 (except for 1988), because of the rous gastropod Lacuna vincco, and juvenile predominance of mytilids, Capre114, and Asteriidae, dominants were peracarid Riatella. The typically mid-depth algae crustaceans such as Pontogenela inermis, Phy11ophora spp. was the dominant at this Idotes phosphorea, I. balchica, Jassa station (Table 6-4). The 1992 collections marmorata, Callioplus laeviusculus, and at all tout stations were similar to Ischyrocerus angulpes (Table 6-12). Rela- previous years, and thus placed in the tively high densities of the latter five same group. During the operational species distinguished the shallow subtidal period, numbers of Poncogenela inermis and area from other areas. Stations B17 and Flatella sp. were below the preopera-B35 were placed in this group every year tional average, and numbers of the except for B17 in 1990. The sample from barnacle Balanus crenatus were above Station B17 in 1990 had well below average average. These minor differences were not numbers of Jassa, Callioplus and Ischyro- enough to cause changes in group cerus and was classified with the mid- assignments. The operational average depth group. In 1991 and in 1992, the densities for all other species were species composition and abundance at within the 95% confidence limits of the Station B17 were similar to the preopera- preoperational averages. tional period, and the collections were placed in the shallow subtidal assemblage Collections at deep Stations B04, B34, again (Figure 6-4) . During the operation- and B13 in past years (1978-84, 1988) al period, abundances of the sessile characterized Group 4. The assemblage in bivalves Mytilidae and Flate11a sp. Group 4 typically had a low total density decreased and were below the preopera- of macrof auna when compared to shallower tional average. The abundance of Lacuna stations, due to low numbers of bivalve vincta increased during the operational molluscs, particularly Hytilidae, Anomia period, and all other species were within sp., and Flatella sp. Crustaceans such the 95% confidence limits of the pre- as Poncogenela inerals, and Capre11a operational mean (Table 6-1:4). septentrionalls and juvenile starfish, As teriidae, took on greater importance in 6-35
r MARINE HACROBENTH05 this depth zone. Species with low always had a lower frequency of Balanus abundance at shallower stations such as spp. than the farfield station. The the northern red chiton, Tonicella rubra, average percent frequency of occurrence the tube-building fan worm, Thelepus over all seasons during the operational clncinnaeus, and the sessile bivalve, period (1991-1992) was quite close to the
#usculus niger were most abundant at deep preoperational average at both stations, stations. During the operational period, and well within the preoperational range collections f rom both near- and f arfield (Table 6-13) . The herbivorous gastropod, deep stations (B04 and B34) were placed Littorina saxatills, was also an important in this group. During the operational constituent of the bare rock community, period Anomia sp. and Balanus cronatus showing lower frequencies in April than increased in abundance, and Pontogenela in July or December during the preopera-inermis, Ton / cella rubra and Capre11a tional period. The mean percent frequency septentrionalls were below the lower 95% of L. saxatills during all seasons of the confidunce limit of the preoperational operational period at both stations was average. However, these changes were within the preoperational range.
minor and did not cause shifts in group assignments. Fucold-covered ledge areas at.approxi-mately mean sea level were characterized Group 5 consisted of only four samples, by a heavy cover of the perennial algae three of which were taken in 1978 at Fucus spp. (mainly F. vesiculosus)(Table Stations B19, B31, and B04. The group was 6-7). During both the preoperational and characterized by relatively low abundances operational periods, Mytilidae was the of the molluscs Mytilidae, Flate114 sp. , most common macrofaunal taxon at nearfield Lacuna vincta and Anomia sp. , and high Station B1, with high frequencies during densities of Pontogenela inermis. No all three sample periods (Table 6-13). collections have been similar to Group 5 Hytilidao usually did not show high since 1980. frequencies at Station B5, where Balanus spp. were more common. The herbivorous gastropod, Littorina obtusata, was common Intertih l Communities at both mid-intertidal stations. Frequen-(Non-destructive Monitoring cies during the oporational period were Prograal within the baselir,e range at both sta-tions, although frequencies at B5 had The bare rock areas near mean high water increased (Table 6-l',). at both near- and farfield stations supported low percentages of algae such The Chondrus zone, at approximately mean as Urospora pencilliformis/Ulothrix flacca low water, was characterized by rock ledge and Tucus spp. (Table 6-7). The predom- with a thick cover of red algae, mainly inant macrof aunal resident was Balanus Chondrus crispus and Mastocarpus stel-spp. , which was most abundant in the bare lacus. At Station B5, the encrusting red rock habitat (NAI 1992a). Proopera- algae Corallina o/Itcinalls was frequently tidnally, the nearfield station almost encountered (Table 6-7). Of the macro-6-36
TABLE 6-13. PERCENT FREQUENCY OF OCCURRENCE BY SEASON AND OVER ALL SEASONS OF THE DOMINANT FAUNA WITHIN PERMANENT 0.25m2 QUADRATS AT THE UPPER (BARE ROCK), MID- (FUCOID ZONE) AND LOWER (Chondrus ZONE) INTERTIDAL ZONES AT NEARFIELD B1 (OUTER SUNK ROCKS) AND FARFIELD B5 (RYE LEDGE) DURING THE PREOPERATIONAL AND OPERATIONAL (1991-92) PERIODS AND IN 1992. SEABROOK OPERATIONAL REPORT, 1992. ZONE */ SPECIES STATION PERIOD / YEAR APR JUL DEC ALL SEASONS d BARE ROCK Balanus spp.b B1 Preop Median
- 61 51 9 40.3 Preop Range (4-100) (9-88) (0-88) (0-100) 1992 51 79 74 68.0 Op Median 46 62.5 61 56.5 Op Range (41-51) (46-79) (48-74) (41-79)
B5 Preop Median 89 85 72 82.0 Preop Range (58-100) (24-100) (5-100) (5-100) T 1992 70 60 50 60
$ Op Median 82.5 63.5 30.5 58.8 Op Range (70-95) (60-67) (11-50) (11-95)
Littorina saxatills B1 Preop Median 7 57 16 26.7 Preop Range (0-44) (0-88) (0-88) (0-88) 1992 25 81 75 60.3 Op Median 31 81 37.5 49.8 Op Range (25-37) (81) (0-75) (0-81) B5 Preop Median 50 66 75 63.7 Preop Range (0-100) (38-94) (0-100) (0-100) 1992 31 6 19 18.7 Op Median 56 28 34.5 39.5 Op Range (31-81) (6-50) (19-50) (6-81) (continued) i
- - - - - - - - ~ - - - - - - - - - - - - - -
i TABLE 6-13. (CONTINUED) i ZONE */ SPECIES STATION PERIOD / YEAR APR JUL DEC ALL SEASONS d FUCOID ZONE - Mytilidae b B1 Preop Median 82 76 78 78.7 Preop Range (37-100) (27-100) (43-10) (27-100) 1992 91 99 19 69.7 Op Median 87 96 57 80 Op Range ~ (83-91) (93-99) (19-95) (19-99) B5 Preop Median 8 1 5 4.7 Preop Range (2-100) (0-100) (0-100) (0-100) 1992 9 19 0 9.3 m Op Median 7 9.5 5.5 7.3 h Op Range (5-9) (0-19) (0-11) (0-19) Littorina obtusata B1 Preop Median 3 10 6 6.3 Preop Range (0-6) (0-25) (6-19) (0-25) 1992 6 0 0 2.0 ^ Op Median 6 8 6 6.7 Op Range 6 (0-19) (0-12) (0-19) B5 Preop Median 3 16 7- 8.7 - Preop kange (0-25) (0-44) (0-44) (0-44) ' 1992 0 25 12 -12.3 Op Median 6 28 24.5 19.5 Op Range (0-12) (25-31) (12-37) (0-37) (continued)
TABLE 6-13. (CORTINUED) , ZONE */ SPECIES STATION PERIOD / YEAR APR JUL DEC ALL SEASONSd CHONDRUS ZONE Mytilidae B1 Preop Median 90 89 65 81.3 Preop Range (54-95) (71-95) (15-85) (15-95) 1992 67 76 93 78.7 Op Median 81 85.5 78 81.5 Op Range (67-95) (76-95) (63-93) (63-95) B5 Preop Median 49 63 26 46' Preop Range (10-72) (23-80) (0-49) (0-80) 1992 21 53 49 41 p Op Median 10.5 40 28.5 26.3. u Op Range (0-21) (27-53) (8-49) (0-53) Hucella lapillus B1 Preop Median 75 100 56 77.0 Preop Range (13-100) (100) (31-88) (13-200) 1992 25 100 37 54.0 Op Median 53 100 28 60.3 Op Range (25-81) (100) (19-37) (19-100) B5 Preop Median 94 38 69 67 , Preop Range (75-100) (13-56) (56-81) (13-100) 1992 94 50 31 58.3 Op Median 97 43.5 25 55.2 Op Range (94-100) (37-50) (19-31) (19-100) (continued)
TABLE 6-13. (CONTINUED) ZONE */ SPECIES STATION PERIOD / YEAR APR JUL DEC ALL SEASONS d Littorina littorea B1 Preop Median 0 0 0 O Preop Range (0) (0-13) (0-6) (0-13) 1992 0 25 12 12.3 Op Median 9.5 15.5 12 12.3 Op Range (0-19) (6-25) (12) (0-25) B5 Preop Median 81 100 88 89.7 Preop Range (75-100) (94-100) (44-94) (44-100) 1992 94 100 62 85.3 Op Median 87.5 100 35.5 74.3 p Op Range (81-94) (100) (9-62) (9-100) Acmaea testudina11s B1 Preop Median 13 13 13 13.0 Preop Range (6-38) (0-25) (6-81) ~(0-81) 1992 12 12 0 8.0 Op Median 15.5 12 6 11.2 Op Range (12-19) 12 (0-12) (0-19) : B5 Preop Median 0 0 0 0 Preop Range (0-44) (0-13) (0-25) (0-44) 1992 12 12 12 12.0 Op Median 12 9 3 8 Op Range 12 (6-12) (0-6) (0-12)
- Bare ledge station is at upper edge of MSL zone, at approximate mean high water. -Fuccid station is at '
approximate mean sea level mark. Cbondrus zone station is at approximate mean low water mark. N ethod of computing percent frequency varies among taxa (point-contact method for Mytilidae and Balanus since l July-1983, percent frequency of occurrence for all other species). .
- PREOP period.is 1982-89, except for Cbondrus zone, where sampling began in April, 1985. Operational period is
! 1991-92. d l Average of three seasonal medians.
I l l H RINE HACROBENTHOS i faunal species monitored, Nucella lapillus species. Balanus spp. (mainly Balanus and Mytilidae spat were the most fre- crenatus, with some Balanus balanus) quently encountered at both stations typically settled by April. Recruitment (Table 6-13) . During the preoperational continued in some years after the April ; period, Mytilidae had medium-to-high sampling period and densities were higher , I frequencies in April and July with in the August samples, while in other generally lower percentages in December, years April sampling occurred near the The total frequency of mytilids during the settlement peak (NAI 1991b, Table 6-14). operational period was within the range By December, densities were consistently of the preoperational years. The predato- low, as Balanus populations disappeared ry snail, Nucella lapillus, was frequently due to mortality. At Station B19 in the' encountered at both stations in the lower operational period, Balanus spp. set in intertidal zone. Seasonal trends and August in 1991 (later than usual) and in median percent f requencies were close to April in 1992. The average over all those of the preoperational period, and seasons during the operational period was almost all were within the preoperational within one standard deviation of the range. The common periwinkle, Littorina preoperacional average at both stations. llecorea, is an exotic species brought from Europe in the 1840s (Van Patten Anomia sp. was unique among the sessile 1992). It occurred in high frequencies taxa that were examined, showing a pattern only at Station B5 throughout the year. of late sumer-fall recruitment. Although The percent frequency of L. littorea over low densities of Anomia sometimes occurred all seasons increased at Station B1 during on panels by August, numbers were typical-the operational period, although it was ly highest in December when abundances of within the range of the preoperational all other sessile taxa were low, a pattern years. Acmaea testudinalls was enumerated which occurred during both the operational in low-to-moderate frequencies in the and preoperational periods (Table 6-14). Chondrus zone at Station B1 in all years The operational average over all seasons and occasionally at Station B5; f requen- was within one standard deviation of the cies followed the same pattern during the preoperational average, and therefore was operational period, except at the farfield not considered substantially different. Station B5, where an increase occurred during the operational period. Frequen- #1 ate 11a sp. is a sessile bivalve that cies were within the range of the preoper- showed highest densities in August col-ational years at both stations. lections and had low densities in April and December samples during the baseline period. During the operational period, jiubtidal Foulina Community (Bott2 m the seasonal pattern at both stations was Eanel Monitorine Program) similar to the preoperational trend (Table 6-14). The operational average over all Panels set at mid-depth stations (B19, seasons was within one standard deviation B31) near the bottom provide information of the preoperational average at both on recruitment of four sessile macrofaunal stations. #1ste11a sp. larvae were typi-6-41
. i TAB 12 6-14. ESTIMATED DENSITY (per O.2.5 m') 0F SELECTED SESSILE TAXA ON HARD-SUBSTRATE BOTTOM PANELS EXPOSED FOR FOUR MONTHS AT '
STATIONS B19 AND B31 SAMPLED T11 ANNUALLY ( APRIL, AUGUST, DECEMBER) FROM 1981-1992 (EXCEPT 1985 AND L990). SEABROOK OPERATIONAL REPORT,1992. , i
- A.P R AUG NOV ALL SEASONS i TAXA PERIOD / YEAR STATION MEAN SD MEAN SD MEAN SD HEAN SD Jalamus spp. B19 17053 13793 6403 4973 9 13 7822 8610 Prg* 802 0 0 10281 9386 (*
Op B19 18393 17501 12450 1991 B19 6017 - 11883 - 0 - 5967 - 1992 B19 30767 - 13017 - 0 - 14595 - Pro B31 40962 22611 7917 6166 14 17 16298 21722 o Op B31 23200 11833 7175 2039 0 0 10125 11878 . 1991 B31 14833 - 8617 - 0 - 7817 - 1992 B31 31567 - 5733 - 0 - 12433 - A:2cela sp. Pro B19 <1 <1 31 68 1232 1136 421 703 i Op B19 124 98 83 100 2600 1934 936 1442 1991 B19 193 - 154 - 1232 - 526 - 1992 B19 54 - 12 - 3967 - 1344 - Pro B31 0 0 36 42 993 1246 343 563 , Op B31 8 6 202 193 556 126 255 278 ' 1991 B31 4 - 338 - 645 - 329 - es 467 181 g 1992 B31 12 - 65 - - N Elarella sp. Pre B19 1 2 3966 2595 27 31 1331 2282 Op B19 5 2 5532 2944 1 1 1846 3192 1991 B19 3 - 3450 - 2 - 1152 - 1992 B19 6 - 7614 - 0 - 2540 - Pro B31 <1 <1 11659 10594 16 21 3392 6727 Op B31 4 3 21569 3363 16 22 7196 12447 1991 231 2 - 23947 - 31 - 7993 - 1992 B31 6 - 19191 - 0 - 6399 - Myrilidae Pro B19 2 3 367 247 58 57 142 197 Op B19 133 110 3122 3655 56 0 1104 1748 1991 B19 55 - 537 - 56 - 216 - 1992 BIS 210 - 5706 - 56 - 1991 - Pro B31 8 11 '5035 10054 36 36 1693 2894 Op B31 37 25 6523 1172 58 76 2206~ 3739 1991 B31 19 - 7351 - 112 - 2494 - 1992 B31 54 -
.5694 - 4 -
1917 -
- Preop: 1981-1984 (Balaams and Anomia B19); 1982-1984 (Balanus and Anomia, B31); 1983-1984 (Flars11a and Mytillidae, B19 and B31);
, Dec. 1986-1989 (all taxa and stations). 4 5 1991-92
I MARINE MACROBENTHOS cally highest from May through July, flounder subtidally (Witman 1985, Ojeda although in some years densities remained and Dearborn 1991). It attaches to hard i high through the end of sampling in substrate with strong byssal threads, and October (see Section 4.0), forms a habitat for many other species. During the preoperational period, In the intertidal zone, annual Mytilidae Mytilidae spat had generally settled on abundances have been variable during the bottom panels by August, with numbers preoperational period (NAI 1991b). gre'atly reduced by December. The pattern Abundances in 1992 showed a dramatic during the operational period was similar increase over the low values recorded in (Table 6-14) . Nytilus edulls larvae were 1991, which were the lowest recorded to typically most abundant in June and July, date, to levels that were within the 95% but were present from May-October (Section confidence limits of the preoperational 4.0). During August 1992 at Station B19, mean (NAI 1992a, Tabic 6-15). However, the density of mytilids was over an order averages for the two year operational of magnitude above the preoperational period at both near- and farfield stations average. Because of the high density in were significantly lower than the preoper-August 1992, the operational average over ational mean (Tables 6-15, 6-16). Spatial all seasons at B19 was well above the dif ferences have been consistent through-preoperational average, while the density out the study, as densities were signifi-at B31 was near average. Because of the cant!*r higher at B1MLW than at B5MLW high standard deviation of the preopera- during the preoperational and operational tional mean (an indication of among-year periods (Tables 6-15, 6-16). . variability), the operational increase at B19 is probably a result of natural Among year trends in mytilid densities variability, in the shallow subtidal zone (Stations B17, B35) parallelled those in the in-tertidal. Abundances in 1992 (Table 6-15) .l 6.3.2.2 Selected Benthis_stm in increased at both stations from the below-average levels that occurred in 1991 (NAI Mytilidae 1992a). 1992 densities at B17 were within the 95% confidence limits of the preopera-Mytilidae, composed primarily of juve- tional mean, although lower than average. nile (<25 mm) Nycilus edulis, was the At Station B35, . 1992 densities were j overwhelming dominant in the intertidal similar to the preoperational mean (Table sone, and was accng the dominant taxa in 6-15). Mytilid abundances averaged over the shallow subtidal and mid-depth zones the two-year operational period were (Table 6-12). Nycilus edu11s, the blue significantly lower than tne preopera-mussel, is an important prey species for tional mean at both stations (Tables 6-15, the dogwinkle Nucella lapillus in the 6-16). l intertidal zone (Mange 1983) and for lob-ster, starfish, Cancer crabs, and fish such as cunner, yellowtail, and winter l l 6-43 I l
l l HARINE HACROBENTHOS l TABLE 6-15. GEOMETRIC HEAN DENSITY (NO./SQ. METER) AND UPPER AND LOWER 95% CONFIDENCE LIMITS AND 1992 AND OPERATIONAL HEANS FOR SELECTED BENTHIC MACROFAUNAL SPECIES AT NEARFIELD-FARFIELD STATION PAIRS. SEABROOK OPERATIONAL REPORT, 1992. SPECIES STATION" PREOPERATIONAL b 1992 OP' LOWER HEAN UPPER HEAN HEAN C.L. C.L. Mytilidae B1MLW 99961 121297 147185 174024 77318 B5MLW 61846 72831 85768 80902 44684 B17 1820' 2580 3657 1821 1073 B35 2917 4449 6787 5163 3232 ' B19 1180 1947 3212 1994 2963 B31 3642 6196 10541 2244 5019 Nucella lapillus B1MLW 1563 1970 2482 852 839 B5MLW 795 905 1030 451 469 Asteriidae B17 465 590 748 416 602 B35 118 184 287 21 105 Pontogenela inermis B19 526 604 694 1142 666 B31 329 404 497 427 233 Jassa marmorata B17 776 1045 1408 2139 1636 B35 1298 1888 2745 3755 3481 Ampithoe rubricata B1MLW 6 19 60 1 0 B5MLW 1 3 9 135~ 167 Strongylocentratus B19 44 66 99 62 45 droebachtensis B31 20 31 46 22 22 Nodlolus modlolus d B19 90 100 110 76 82 B31 72 89 106 61 71 4
'Nearfield = B1MLW, B17, B19; Farfield = B5MLW, B35, B31.
b Prooperational = mean of annual means, 1978-1989 (B1MLW, B17, B19, B31) or 1982-1989 (B5MLW, B35).
'Op = operational mean, 1991-1992; mean of annual means, d
Arithmetic mean of annual means. Preop = 1980-1989, Op = 1991-1992. 1 l I 6-44 ____ _ _ _ __ _ _ - _ _= - - - _ _- = -___-_ _ -
T r ' TABLE 6-16. RESULTS OF ANALYSIS OF VARIANCE COMPARING LOG-TRANSFORMED DENSITIES.0F SELECTED BENTHIC SPECIES AT NEAR- AND FARFIELD STATION PAIRS (B1MLW/B5MLW, B17/B35, B19/B31) DURING PREOPERATIONAL (THROUGH 1989) AND OPERATIONAL (1991 AND 1992) PERIODS. SEABROOK OPERATIONAL REPORT, 1992. , SAMPLED IN MAY. AUGUST. NOVEMBER STATION SOURCE OF SPECIES
- PAIRS VARIATION df SS Fh MULTIPE COMPARISONSf (ranked in decreasing order)
Mytilidae B1MLW Preop-Op* 1 1.89 16.00*** Op< Preop (<25 mm) B5MLW Year (Preop-Op) 12 10.24 7.23*** BIMLW>B5MLW Month (Year) 28 24.34 7.36*** Station d 1 2.61 22.13*** Preop-Op X Station
- 1 0.00 0.00 NS Error 276 32.60 i B17 Preop-Op 1 3.19 13.31*** Op< Preop
$ B35 Year (Preop-Op) 12 23.82 8.29*** B17>B35 Month (Year) 28 63.95 9.54***
Station 1 5.74 23.98*** Preop-Op X Station 1 0.71 2.96 NS Error 268 64.14 B19 Preop-Op 1 0.11 0.29 NS B31 Year (Preop-Op) 12 66.50 15.46*** Month (Year) 28 34.42, 3.43*** Station 1 6.85 19.10*** B19>B31 Preop-Op X Station 1 0.99 2.75 NS Error 327 117.21 (continued)
TABLE 6-16. (Continued) SAMPLED IN MAY. AUGUST. NOVEMBER ! STATION SOURCE OF HULTIPIE SPECIES
- PAIRS VARIATION df SS @ COMPARISONS' (ranked in decreasing order)
Nucella lapillus B1MLW Preop-Op 1 5.69 43.74*** Op<Preep B5MLW Year (Preop-Op) 12 6.47 4.14*** Month (Year) 28 25.22 6.92*** Station 1 3.45 26.53*** B1MLW>B5MLW Preop-Op X Station 1 0.02 0.16 NS Error 276 35.91 Asteriidae B17 Preop-Op 1 1.08 7.91** i B35 Year (Preop-Op) 12 27.16 16.50***
$ Month (Year) 28 18.17 4.73***
Station 1 16.31 118.92*** Preop-Op X Station 1 1.16 8.49** B17 On B17 Pre B35 Pre B35 Op Error 268 36.75 Pontogensia inermis B19 Preop-Op 1 0.48 2.40 NS B31 Year (Preop-Op) 12 10.65 4.44*** Month (Year) 28 31.28 5.58*** B19 OP B19 Pre B31 Pre B31 Op Station 1 5.31 26.52*** Preop-Op X Station 1 0.85 4.25* Error 327 65.43 Jassa marmoraca B17 Preop-Op 1- 2.19 6.82** Op> Preop B35 Year (Preop-Op) 12 16.35 4.24*** Month (Year) 28 22.39 2.49*** Station 1 3.92 12.21** B35>B17 Preop-Op X Station 1 0.06 0.17 NS Error 268 86.12 (continued)
TABIE 6-16. (Continued) SAMPLED IN MAY. AUGUST. NOVEMBER STATION SOURCE OF MULTIPLE SPECIES
- PAIRS VARIATION df SS Fb COMPARISONS I (ranked in decreasing order)
Aspitboe rubricata B1MLW Preop-Op 1 0.58 1.54 NS B5MLW Year (Preop-Op) 12 236.02 52.64*** Month (Year) 28 32.69 3.12*** Station 1 51.14 136.85*** Preop-Op X Station 1 46.85 125.38*** B5 Op B5 Pre El Pre B1 Op Error 276 103.13 Strongylocentrotus B19 Preop-Op 1 1.14 2.33 NS droebachiensis B31 Year (Preop-Op) 12 38.92 6.62*** , Month (Year) 28 41.60 3.03*** k Station 1 5.60 11.43* Preop-Op X Station 1 0.04 0.08 NS Error 327 160.30 Nodfolus modfolus B19 Preop-Op I 323648.31 20.06*** Op< Preop (adults) B31 Year (Preop-Op) 10 1253622.52 7.77*** Month (Year) 242 778195.07 2.01** Station 1 165.76 0.01 NS Preop-Op X Station 1 6167.42 0.38 NS Error 819 13211100.02
- Log (x+1) density, except for N. modfolus adults, were sampled semi quantitatively and were compared with rank densities.
NS = Not significant (p>0.05)
* = Significant (0.051p>0.01)
** = Highly significant (0.012p>0.001)
*** = Very highly significant (p50.001)
*Preoperational (through 1989) versus Operational (1991 and 1992) period, regardless of station Nearfield = Stations 1MLW, B17, and B19; farfield = Stations B5MLW, B35, B31, regardless of year / period
" Interaction between main effects-
' Underlining signifies'no significant differences (alpha 5 0.05) among least squares means with a paired t-test.
MARINE HACROBENT110S In the mid-depth zone, Myt111dae abun- tional mean length was smaller than L dances in 1992 decreased from the higher- average. The average length in 1992 and than-average levels reported in 1991 during the operational period at both (Table 6-15, NAI 1992a). Average abun- stations was within the range of previous dances during the operational period were years (NAI 1991h). not significantly different from the preoperational average (Table 6-16). In the subtidal zone, the preoperational mean lengths ranged from 2.3 to 2.8 mm. Among-station dif ferances in Mytilidae Mean length in 1992 was larger than the density observed during the preoperational preoperational average and outside the 95% period continued in 1991 and 1992. confidence limits at the two shallow Mytilid abundances at the nearfield subtidal stations and at the mid-depth subtidal stations (B1MLW, B17, B19) f arfield Station B31. Over the two-year historically have been significantly lower operational period, mean lengths were than at their farfield counterparts within the 95% confidence limits of the (B5MLh , B35, B31) . These differences con- preoperational mean at the two farfield tinued during the operational period Stations B31 and B35. Mytilids at Station (Tables 6-15, 6-16). Intertidal densities B17 were larger than the preoperational were one-to-two orders of magnitude higher average during the operational period but than those at the shallow subtidal and within the range of previous years (NAI mid-depth stations , which were generally 1991b). At B19, mytilid lengths in 1992 similar, were slightly smaller than the preopera-tional average, as there were few indi-viduals measuring more than 4 mm (NAI Nycilus edulis range up to 100 mm in length (Gosner 1978). The Mytilidae col- 1993). The average length for the lected in this study ranged from less than operational period was smaller than the 1 mm to 25 mm in length. The majority of lower 95% confidence limit of the pre-mytilids collec*.ed have been newly-settled operational mean (Table 6-17). spat measuring 2-3 mm (Table 6-17). Historically, intertidal mytilids were Ilistorically, Nyc11us edu11s larvae have slightly langer than those from subtidal been present from mid-May to October zones; this trend continued during the (Section 4. 0) . There were no changes in operational period at all stations. the distribution or abundance of larvae Mytilids from intertidal depths averaged in 1991 or 1992. Settlement on surface j approximately 3 mm in length during the panels occurred year-round, but was preoperational period at both stations. heaviest from June-October (Section 7.0). j In 1992 and during the operational period Recruitment to the benthic habitat, as as a whole, the average length at Station indicated by the appearance.of individuals B1MLW was larger than average and outside measuring 1 mm, historically has occurred the 95% confidence limits of the preopera- from August-October, with some individuals tional mean. At Station B5HLW, the occasionally appearing in ' April or May. average length in 1992 was similar to the (NAI 1985). In 1992, low numbers of 1-mm preoperational mean, although the opera- individuals appeared in May, August, and 6-48
MARINE MACROBENTHOS TABLE 6-17. KEAN LENGTH (MM) AND UPPER AND LOWER 95% CONFIDENCE LIMITS
' DURING THE PRE 0PERATIONAL PERIOD AND 1992 AND OPERATIONAL MEANS FOR SELECTED BENTHIC SPECIES AT NEARFIELD-FARFIELD STATION PAIRS. SEABROOK OPERATIONAL REPORT, 1992.
j PREOPERATIONAL" 1992 OPERATIONALb TAXA STATION LOVER MEAN UPPER HEAN MEAN Mytilidae* B1MLW 3.1 3.1 3.2 3.7 3.5 B5MLW 3.2 3.3 3,3 3.3 3.0 B17 2.3 2.3 2.4 2.6 2.6 B35 2.4 2.5 2.5 2.6 2.4 . B19 2.3 2.4 2.4 1.8 1.9 B31 2.7 2.8 2.9 3.0 2.8 Nucella B1MLW 6.7 6.9 7.0 5.8 5.6 lapillus B5MLW 5.8 6.0 6.2 6.1 5.8 Asteriidae B17 4.8 5.0 5.1 4.4 4.9 ; B35 6.4 6.7 7.1 5.9 5.6 Poncogenolo B19 5.0 5.1 5.3 4.8 5.1 inormis B31 5.2 5.3 5.4 5.3 5.4 Jassa B17 4.1 4.2 4.2 4.5 4.5 marmorata B35 3.9 3.9 4.0 4.2 4.3 , Amplthoo B1MLW 6.7 7.0 7.3 6.5 7.8 j rubricata B5MLW 7.4 7.8 8.2 7.4 7.5 ; Strongylocontrotus B19 1.8 1.9 2.0 1.9 1.7 droebachlensis B31 1.8 1.9 2.0 4.9 3.3 "Preoperational = mean of annual means, 1982-1989. Annual mean is sum of lengths ! of all individuals collected in May, August, and November divided by total number of individuals measured. . b Operational = mean of annual means, 1991 and 1992. Individuals measu.ing >25 mm were excluded. 6-49
MARINE MACROBENTIIOS November at intertidal and shallow and outside the 95% confidence limits subtidal stations'(NAI 1993). At the mid- (Table 6-17), although within the range depth stations, 1-mm mytilids were more of previous years (NAI 1991b). At Station numerous than at shallower depths, and B5MLW, average lengths in 1992 and during were present in May, August and November. the operational period were within the 95% Recruitment on short-term surface panels confidence limits of the preoperational in 1992 was heaviest in June and July mean (Table 6-17). (Section 7.0). Historically, Nucella lapillus re-cruitment in the study area occurred in Nucella lapillus August or September, as indicated by increased numbers of small (2-3 mm) Nucella lapillus, the dogwinkle, is an individuals. Juveniles persisted through important intertidal predator, particu- the winter months, but the seasonal larly on mytilid spat and barnacles (Menge occurrence of adults was sporadic (NAI and Sutherland 1976). It is the sole 1985). In 1992, adult individuals (10-25 benthic predator in the mid-intertidal mm) predominated in May and August, and zone (Menge 1976), joined by starfish high numbers of small (2-3 mm) individuals Astarlas spp. In the low intertidal zone were collected in November at both (Lubchenco and Menge 1978). Densities of stations (NAI 1993). Nucella in 1992 were the lowest recorded to date for the second year in a row at Asteriidae both nearfield and farfield intertidal stations (Table 6-15, NAI 1992a). As a The Asteriidae collected in this study result, mean density during the opera- are juveniles, too small to be assigned tional period was significantly lower than to genus. Two species of both Astoclas the preoperational mean (Table 6-16), and Leptasterias can occur withM the Spatial differences have been consistent study area (Gosner 1978), although throughout the study. Station B1MLW has Asterlas are more common. The species of j had significantly higher densities of Astorias in the study area, A. forbesli ! Nucella than Station B5MLW, parallel 11ng and A. vulgarls, have overlapping geo-the pattern of its most important prey, graphic cnd bathymetric distributions mytilld spat (Tables 6-15, 6-16). (Henge 1979). Both species are considered to have a major role in regulating the Nucella lapillus can reach up to 51 mm intertidal community because of their in length (Abbott 1974). During this intense and nearly-exclusive predation on study, annual mean lengths ranged from 3- mussels. They are second only to urchins i 12 mm during the preoperational period in their importance as predators in the (NAI 1991b), averaging 6.5 mm at the two shallow subtidal zone, feeding mainly on intertidal stations (Table 6-17). Average mussels (Sebens 1985a). Although Asteril-annual lengths in 1992 and during the dae occurred in all depth zones, abun-operational period at Station B1MLV were dances were highest at shallow subtidal smaller than the preoperational average depths (B17,B35)(NAI 1993). 6-50 i l
MARINE MACROBENTHOS Asteriidae abundances in 1992 decreased doninant species in both benthic (Table from 1991 levels at both Stations B17 and 6-12) and macrozooplankton collections B35 (NAI 1992a; Table 6-15). At Station (Section 4.0). It clings to submerged B35, 1992 abundances were the lowest algae from the lower intertidal to depths recorded during this study (Table 6-15; greater than 10 m (Bousfield 1973). NAI 1991b). When averaged for the operational period, abundances at B17 were Pontogenela inermis was a dominant at not significantly different from the all of the subtidal stations (Table 6-12). preoperational average; however at B35, Abundances in 1992 were higher than the the operational mean abundance was preoperational average at B19, but similar significantly lower than the preopera- to the preoperational average at B31 tional mean (Tables 6-15, 6-16), (Table 6-15) . No significant differences in mean density were found between the Adult sea stars generally measure more operational and preoperational periods at than 100 mm, tip-to-tip. For example, the nearfield Station B19,' but densities Asterlas forbesil ranges up to 125 mm in at the farfield station were significantly length, and A, vulgarls may reach 200 mm lower during the operational period (Gosner 1978) . During the preoperational (Tables 6-15, 6-16). Densities of P. period, Asteriidae averaged approximately inerals at B31 first declined in 1990, 5 mm in length at Station B17 and 7 mm at prior to plant operation (NAI 1991b). Station B35 (Table 6-16). Average lengths Spatial differences have been consistent in 1992 were smaller than the preopera- throughout the study, with significantly ; tional average at both stations. The higher abundances at B19 in comparison to ' average for the two-year operational B31 (Table 6-16), period at B17 was similar to the preoperational mean, but at B35 was Pontogenela increls ranges up to 11 mm smaller than the lower 95% confidence in length (Bousfield 1973). P. inermis limits of the preoperational mean, collected at mid-depth stations averaged Historically, newly-settled rect aits (1-3 approximately 5 mm in length during the , mm) appeared in summer samples (NAI 1985), preoperational period. In 1992, average ~ l In 1992, Asteriidae measuring 1-3 mm lengths were smaller than the preopera-predominated in May and August at Station tional average at Station B19 but at B31 B17, suggesting recruitment was occurring were within the 95% confidence limits of at this time. Asterilds were relatively the preoperational mean (Table 6-17). For rare at B35 in 1992, but several individu- the operational period as a whole, mean als measuring 1-3 mm were collected in May lengths were similar to the preoperational and August (NAI 1993), means at both stations. Trends in the presence of ovigerous Pontorenels inermis females and the appearance of juveniles can be used as an indicator of reproduc-Pontogenela inerals is a pelagic, cold tive success. According to Bousfield water amphipod (Bousfield 1973), and a (1973), P. lnerals has an annual life 6-51
HARINE MACROBENTHOS cycle, with ovigerous females present in Jassa marmorata ranges up to 9 mm in winter and spring. In this study, re- length (Bousfield 1973). In a New York productive females have historically been study, adult females averaged approxi-collected in low numbers from January mately 7 mm in length in spring, but their through September (NAI 1985). In 1992, average size steadily decreased to ovigorous females were collected in August approximately 4 mm in summer (Franz 1989) . at both stations (NAI 1993). Recruitment, The population was characterized by as indicated by the appearance of individ- multiple overlapping generations, uals measuring 1-3 mm, historically Individuals from this study averaged occurred between May and July (NAI 1985). approximately 4 mm during the preopera-In 1992, juveniles measuring 1-3 mm tional period, representing a mixture of appeared in moderate numbers in May, juveniles and adults. Average length in consistent with previous years (NAI 1993). 1992 and during the operational period was larger than the upper 95% confidence limit of the preoperational mean at both Jassa marmorata stations (Table 6-17). Jassa marmoraca is a ubiquitous and Historically, reproductive females have abundant fouling organism in areas with been collected year-round, but were more strong tidal and wave currents (Bousfield abundant from April-November. Large 1973). Its open-ended tubes collect numbers of juveniles measuring 1-2 mm sediment and detritus, forming a mat appeared in July and occurred for the complex over the hard substrate (Sebens remainder of the year (NAI 1985). In 1985a). An omnivorous suspension feeder, 1992, ovigerous females were collected it feeds on both live and dead plant and during all three sampling dates. Repro-animal material (Nair and Anger 1979), ductive females settled on short-term It is one of the dominant species on surface panels from May-December, but were surf ace fouling panels (Section 7.0) and most numerous in August and September (NAI in the shallow subtidal community (Table 1993). Individuals measuring 1-3 mm were 6-12). numerous in subtidal samples in August and November. Recruitment on short-term Densities of Jossa in 1992 were higher surface panels occurred continuously from than the preoperational average for the June-December (NAI 1993). second year in a row at B17 and B35 (Table 6-15; NAI 1992a). The average for the two-year operational period was signifi- Amoithon rubricata cantly higher than the preoperational mean at both stations (Table 6-16). Throughout Ampichoe rubricaca is an amphi-Atlantic the study, densities have been signifi- amphipod that ranges from Labrador south cantly higher at B35 than at B17 (Tables to Long Island Sound (Bousfield 1973). )
.I 6-15,6-16). In this study, it has been found primarily in intertidal areas, but is occasionally common at shallow subtidal stations.
6-52
i MARINE MACROBENTH0S j I Primarily herbivorous, hpichos spends were monitored by the appearance of j most of its life in a nest constructed in ovigerous females and juvenile specimens macroalgae (Skutch 1926). hplchoe was measuring 1-3 mm, Ovigorous and brooding one of the dominant intertidal crustaceans females were rare, but during the pre-through 1982, but was rarely collected operational period were occasionally f rom 1984-1989 (NAI 1991b). Low numbers collected from April through September were collected in 1990 at B5MLW, followed (NAI 1985). No ovigerous females were by moderate densities in 1991 and 1992 collected in 1991 or 1992 (NAI 1992b, (NAI 1991b,1992a, Table 6-15). The mean 1993). Historically, the largest numbers density during the operational period at of small (1-3 mm) individuals were station 85MLW was significantly higher collected from April through September, than the preoperational mean (Table 6-16). suggesting recruitment occurred during At the nearfield Station B1MLW, however, this time period. In 1983 and 1984, few hpithoe were collected in 1991 or recruitment appeared depressed, accounting 1992, resulting in significantly lower for both lower overall densities and densities during the operational period larger mean size (NAI 1985). This trend in comparison to the preoperational period continued through 1991 (NAI 1992a). In (Tables 6-15, 6-16). There was no ap- 1992, moderate numbers of individuals parent reason for the disappearance of measuring 1-3 mm appeared in August at h pichoe from the intertidal zone from B5MLW. However, at B1MLW, no individuals 1984-1989, nor any explanation why in this size range were collected in 1992 densities have recovered at the farfield (NAI 1993). station. hpithoe rubricata ranges in length from Stronerlocentrotus droebachlensis 14-20 mm (Bousfield 1973). During the preoperational period, hpithoe from the Strongylocentrotus droebachlensis, the intertidal zone everaged 7-8 mm (Table 6- green sea urchin, is distributed from the 16), reflecting the mixture of juveniles Artic south to New Jersey-(Gosner 1978). and adults. The average annual length in It is an omnivore, but prefers grazing on 1992 was smaller than the preoperational Laarinaria saccharina over other common average at B1MLW, but the two year algal species (Larson et al. 1980; Mann operational average was larger than the et al .1984) . When the macroalgae supply preoperational mean. As length measure- is depleted, it will prey on Nyt/lus ments at B1MLW are based on only a few edu11s (Briscoe and Sebens 1988). Sebens individuals, they are not reliable (1985a) named S. droebachtensis as the estimates of the population length. At most important predator in the 6-18 m hard Station B5MLW, average annual lengths in substrate habitat, in large part responsi-1992 and during the operational period ble for the multiple steady states typical were within the 95% confidence limits of in this habitat. When urchin densities the preoperational mean (Table 6-17), are low, foliose algal species prolifer-ate. However, population explosions lead , Trends in reproduction and recruitment to the eradication of all foliose algal ) I 6-53
HARINE HACROBENTHOS i species, leaving only crustose coralline 2 mm in diameter during the preoperational algae. This has occurred on the Canadian period (Table 6-17). The average length Atlantic Coast (Breen and Mann 1976). In in 1992 at B19 was similar to the preoper-the New Hampshire area, large numbers of ational average, but for the two year green sea urchins were responsible for operational period was smaller than the creating algae barrens near the Isles of preoperational average. At B31, however, Shoals in 1981 (Witman 1985). Predators the average length in 1992 was 4.9 mm, the that can control urchin populations highest recorded to date (NAI 1991b). Include the Jonah crab Cancer borealls, Relatively few measurable urchins were ocean pout, and to a lesser extent, the collected at B31 in 1992, and nearly a American lobster (Sebens 1985b). third measured 6-15 mm (NAI 1993). This resulted in a larger-than-average annual Newly-recruited urchins were collected length. In destructive samples, but were not common. During the preoperational period, Ilistorically, newly-settled individuals average density ranged from 31 (Station have been collected in August and Sep-B31) to 66 (B19)(Table 6-15). Abundances tember (NAI 1985). Large numbers of 1-mm in 1991 and 1992 were not significantly urchins appeared in 1992 in November at different from previous years (Table 6- B19 but few were collected at Station B31 16). Densities have been significantly throughout the year (NAI 1993). - i higher at Station B19 in comparison to B31 throughout the study (Tables 6-15,6-16). Adult urchins, enumerated in the tran-2 sect program, have been relatively rare Adult sea urchins measure up to 75 mm since monitoring began in 1985 (Table 6-in diameter (Gosner 1978). Most of the 18). Peak numbers have never exceeded individuals collected subtidally were 1.3/m . Urchin densities were low in 1991, 2 juvenile, with lengths averaging close to ranging from 0 to 0.05/m for the year. 2 TABLE 6-18. HEAN DENSITIES (per m ) AND RANGE DLTRING THE PREOPERATIONAL PERIOD (1985-1989) AND HEAN IN 1991 AND 1992 0F ADULT SEA URCHINS. SEABROOK OPERATIONAL REPORT, 1992. PREOPERATIONAL OPERATIONAL STATION HEAN RANGE 1991 1992 NEAN l B17 0.2 0-1.3 0.05 0.01 0.03 l B35 0.1 0-0.5 0 0 0 B19 0.09 0.02-0.2 0.01 0.76 0.39 B31 0.04 0-0.26 0 0.06 0.03 Mean 0.1 0-1,3 0.02 0.2 6-54 ) 1
, MARINE MACROBElfTHOS Urchin numbers at the mid-depth Stations 6.4 DISCUSSION B19 and B31 increased in 1992. At B19, 0.76 urchins per square meter were 6.4.1 Introduction collected on transects. He ever, the number averaged over all four subtidt.?. Benthic communities are monitored for 2 atations (0.2/m ) was within the range of two types of discharge effects. Exposure previous years. Consistently-low numbers to elevated temperatures from the dis-of adult urchins indicate that this charge plume would be most likely to occur species is not becoming a nuisance species in surface and near-surface waters because in the study area. of the plume's buoyancy. Although temperature increases have been shown to be unlikely at intertidal areas at the Modlolus modlolus Outer Sunk Rocks and shallow subtidal
#odlolus modlolus, the northern horse areas (Teyssandier et al.1974, Padmana-mussel, replaces the blue mussel at depths bhan and Hecker 1991), these sites are from 10-20 m (0jeda and Dearborn 1989). monitored for possible plume effects. The #odlolus exhibits a clumped distribution, operation of Seabrook Station is being settling in persistent beds that create evaluated to determine whether there is a microhabitat and refuge for a diversity increased detritus resulting from en-of other benthic organisms. Nodlolus beds trained organisms that affects the have been found to have significantly benthos. This effect, if it occurs, would higher densities of infauna in comparison be most likely in the immediate vicinity to adjacent areas without #odlolus, of the discharge (Stations B19 and B04).
possibly because of sediment accumulation, reduced flow, increased food, and protec-tion from predators (Witman 1985). 6.4.2 Potential Discharge Effects on Intertidal / Shallow Subtidal Hodiolus modiolus densities were sig- Benthic Community nificantly lower during the operational period at both near- and farfield stations 6.4.2.1 JLrickeround ; (Tables 6-15, 6-16). In 1992, densities l decreased from levels in 1991, but were ,The intertidal and shallow subtidal l within the range of previous years (NAI horizontal ledge benthic communities are ; 1991b). Spatial differences were consis- characterized by a thick cover of red I tent throughout the study, as significant- algae (mainly Chondrus crispus) and large ly higher densities occurred at B19 in numbers of juvenile mussels (mainly 'l comparison to B31. Modfolus are suscepti- Nycilus edulls, the blue mussel). These ) ble to storm damage caused by increased two species provide cover and habitat for drag from epiphytic growth by kelps -1985 other algae, bivalves and crustaceans. (Witman 1985) . Strong f all storms in 1991 and 1992 may have reduced the numbers of The intertidal and shallow subtidal
#odlolus in the study area. benthic communities are not exposed to 6-55
HARINE HACROBENTIIOS substantial (>1'F) temperature increases samples wera considered, total biomass and resulting f rom plant operation. The areal biomass of C. crispus showed no signifi-coverage of the discharge plume and likely cant difforence from historical levels, temperature increase have been modeled Values reported in 1992 increased from under several current regimes and meteo- levels in 1990 and 1991, suggesting that rological conditions (Toyssandler 1974). the trend is reversing. Thus the reduced A recent study to validate model results biomass reflects natural year-to-year for the discharge plume showed no moa- variability rather than plant operation. surable temperature increase at the Outer Sunk Rocks under the conditions tested Four benthic algal and f aunal taxa woro (Padmanabhan and Hecker 1991). Tempera- intensively studied as representative ture increases at shallow subtidal depths important species of the intertidal (4.6 m in the area of the benthic sta- habitat. They were selected based on tions) were less than 0.6*C (l'F). their importance as dominants, habitat-
. formers, and/or predators and represent a variety of temperature tolerances and 6.4.2.2 Intertidal Benthic Community trophic levels. Of the four taxa, only one taxon (Chondrus crispus) showed no Most measures of community structure in change during the operational period. Two the intertidal zone from 1990-1992 worn others (gastropod Nucella lapillus and similar to previous years (Table 6-19). bivalve Mytilidae) showed changes that No permanent changes occurred in the occurred at nearfield and farfield macroalgal and macrofaunal community stations (Table 6-20). During the early composition in 1990, 1991 and 1992 as years of the study, the amphipod Ampichoe indicated by numerical classification. rubricaca was a dominant in the intertidal The numbers of algal and macrofaunal taxa zone, but had disappeared by 1986. This were reduced during the operational species returned to the farfield in-period, however. As reductions occurred tertidal station in 1988, and showed in both nearfield and f arfield areas, they increases in abundances through 1992, but appear to be part of an area-wide trend, was rarely collected at the nearfield sta-tion. As a result, A. rubricaca densities In the low, middle, and high intertidal were significantly higher at the farfield zone, most species showed little change station in comparison to the nearfield in frequency in 1992 and during the station. As this . situation developed operational period in comparison to prior to plant operation, it appears to previous years. Two community measures be a result of natural variability.
showed changes during the operational Considering all aspects of the selected period at the nearfield intertidal intertidal species,'no changes occurred station. Annual total algal biomass was that could be directly related to opera-significantly lower during tho operational tion of Seabrook Station. l period at BlMIN (Table 6-19), mainly due to reduced levels of dominant Chondrus crispus in 1990. However, when triannual 6-56
~- _ - . . - .- - . . - .
TA B LE 6 - 19.
SUMMARY
OF EVALUATION OF DISCHARGE PLUME EFFECTS ON THE BAIANCED INDIGENOUS BENTHIC COHMUNITIES IN VICINITY OF SEABROOK STATION. SEABROOK OPERATIONAL REPORT, 1992. OPERATIONAL NEARFIELD FARFIELD
. PERIOD SIMILAR DIFFERENCES AREA / DEPTH TOPREVIgUS CONSISTENT WITH C0HHUNITY ZONE PARAMETER" YEARS 7 PREVIOUS YEARS 7*
Macroalgae Intertidal No. of taxa Op< Preop yes Total biomass no NF:Op< Preop FF:Op= Preop Community structure yes yes Shallow No. of taxa yes yes subtidal Total biomass yes yes Community structure yes yes Macrofauna Intertidal No. of Taxa Op< Preop yes Total abundance yes yes Community structure yes yes Shallow No. of taxa no NF:Op> Preop subtidal FF:Op= Preop Total density yes yes Community structure yes (1991-92) yes (1991-92)
- Abundance, no. of taxa, biomass, total density, evaluated using ANOVA; community ;
structure evaluated using numerical classification by year and station. b Operational period = 1990-1992 ( August only) NF = nearfield FF = farfield l TABLE 6-20.
SUMMARY
OF EVALUATION OF DISCHARGE PLUME EFFECTS ON REPRESENTATIVE IMPORTANT SPECIES IN VICINITY OF SEADR00K STATION. SEABROOK OPERATIONAL REPORT,1992. NEARFIELD- : FARFIELD l DIFFERENCES j OPERATIONAL CONSISTENT 1 PERIOD SIMILAR WITH TO PREVIOUS PREVIOUS COHHUNITY AREA / DEPTH ZONE SELECTED SPECIES YEARS 7* YEARS?h Macroalgae Intertidal Chondrus crispus yes yes Shallow Subtidal Chondrus crispus Op< Preop yes ! Shallow Subtidal Eaminarla sacebarino yes yes l Shallow Subtidal Eeminaria digicata no NF:Op< Preop FF:Op= Preop l Macrofauna Intertidal Ampichos rubricata no NF:Op< Preop FF:Op> Preop Intertidal Nucella lapillus Op< Preop yes Intertidal Mytilidae Op< Preop yes
]
Shallow Subtidal Jassa marmoraca Op> Preop yes Shallow Subtidal Asteriidae no RF:Op= Preop FF:Op< Preop Shallow Subtidal Mytilidae Op< Preop yes 'Results of analysis of variance. Operational period = 1991-1992. b NF = nearfield FF = farfield. 6-57
l 1 MARINE MACROBENTIIOS I i 6.4.2.3 Shallow Subtidal Benthic tically significant. Densities of L. , Community digitata have been declining since 1989 at the nearfield station (NAI 1989b,1990 The shallow subtidal algal community and 1991b). Reductions during the opera-showed no changes that could be related tional period are a continuation of this to plant operation. Most measures of trend that was initiated prior to com-community structure for both macrofauna mercial operation of the plant. and macroalgae in 1990,1991 and 1992 were similar to historical conditions (Table 6-19). Macrof aunal species composition 6.4.3 Potential Detrital Effects on at B17 in 1990 was more similar to that the Mid-Deoth and Deen Benthic at the mid-depth stations. Ilowever, in Egmmunity 1991 and 1992, community composition was similar to the shallow subtidal stations 6.4.3.1 Backaround in previous years. The number of taxa was significantly higher at the nearfield The extent of change (if any) to the station, due mainly to the high number in community structure of benthic organisms 1990. The number of taxa in 1991 and 1992 in the mid-depth (9-12 m) and deep (18-was within the 95% confidence interval of 21 m) horizontal ledge communities that the preoperational mean, might result from increased detritus from - the discharge plume was evaluated through Of the five benthic selected species in the benthic monitoring program. Changes the shallow subtidal zone, most showed no could be manifested by (1) the enhancement significant changes in abundance or of detritivores and suspension feeders, biomass in 1991 and 1992 that were re- (2) the increased attraction of benthic stricted to the nearfield station (Table feeders caused by locally-increased food 6-20). Numbers of the kelp Laminarla supply, and/or (3) impact on organisms saccharina were similar during the sensitive to the increased detritus operational period to previous years. The resulting from the decay of entrained alga Chondrus crispus, and the macrof aunal organisms. taxa Jassa carnorata and Mytilidae all showed areawide changes in abundance The benthic community was characterized during the operational period. Juvenile by an overstory of kelps (mainly Agarum aster 11ds showed significant reductions cribrosun and Leninarla d/gitata) and an at the farfield station during the oper- understory of macroalgae (Phy11ophora spp. ational period, with no significant and Pellota serrata) along with bivalves differences in density observed at the (Mytilidae, Elate 11a sp. , Anomia sp. ) and nearfield station. The dominant kelp spe- a variety of peracarid crustaceans'. cies Laminarla digitata had significantly Community composition has been relatively lower densities during the operational stable from year-to-year. Although period in the nearfleid area. Although abundance or biomass of individual species l densities were also reduced at the far- occasionally showed significant year-to-field area, this reduction was not statis- year changes, these differences were 6-58
HARINE HACRODENTHOS consistent between nearfield and farfield related to plant operation (Table 6-22). stations. Abundances of amphipod Pontogenela inermis at the nearfield station in 1991 and 1992 were similar to previous years. However, 6.6.3.2 Hid-Death Benthos abundances were significantly lower at the farfield station during 1991 and 1992. Macroalgal community composition at the The kelp Lamir'oria digitata and horso discharge (B19) and farfield (B31) mussel tfodlolus modlolus had reduced stations in 1990, 1991 and 1992, as numbers during the operational period at revealed by numbers of taxa, total bio- both nearfield and f arfield stations. The mass, and numerical classification, was decline in numbers of kelp at the dis-similar in most cases to previous years charge site began in 1988, prior 'to (Table 6-21). Numbers of algal and Seabrook Station operation. . Three taxa, macrofaunal taxa at all three mid-depth Laminarla saccharina, Mytilidae, and sites during the operational period were Strongylocentrotus droebachtensis, the not significantly different from the green sea urchin, showed no change in preoperational period. Algal and macro- abundsnce during the operational period. f aunal community composition at the mid- The green sea urchin has been monitored depth sites during the operational years as a juvenile and adult because of its was similar to previous years. Total potential for becoming a nuisance organ-algal biomass and macrofaunal density dur- 1sm. Population eruptions have occurred ing the operational period was not sig- at the nearby Isle of Shoals, where urchin
- nificantly different from the preoperatio- grazing denuded the substrate of erect nal period at the discharge and farfield algae (Witman 1985) . Juvenile and adult stations. Total biomass and density at sea urchin abundances at Stations B17, the intake station were significantly B35, B19, and B31 in 1991 and 1992 were lower during the operational period in similar to previous years, indicating that comparison to previous years. Reduced the population is stable.
densities of the dominant bivalve Mytili-dae in August led to the decrease in total Algal and macrofaunal community struc-density, paralleling the lower biomass of ture during the operational period was macroalgae. similar to previous years at the discharge and farfield stations. However, some Although benthic community composition changes in the algae and fauna at Station in the mid-depth zone has been stable from B16, near the intake were noted. Total year-to-year, annual variations in algal biomass and macrofaunal density at ' abundance or biomass of representative B16 were significantly lower in 1990, 1991 important species have typically occurred and 1992 in comparison to previous years. during the preoperational period. No changes, howe _ver, were observed at Fluctuations again occurred during the operational period, but most spatial dif ferences remained unchanged, and were part of an area-wide trend, rather than 6-59 l l
TABLE 6-21.
SUMMARY
OF EVALUATION OF DETRITAL RAIN EFFECTS ON THE BALANCED INDICENOUS BERTHIC C0KHUNITIES IN THE VICINITY OF SEABROOK STATION. SEABROOK OPERATIONAL REPORT, 1992. OPERATIONAL NEARFIELD-FARFIELD PERIOD SIMILAR DIFFERENCES AREA /DEPill TOPREVIgUS CONSISTENT WIT 11 COMMUNITY ZONE PARAMETER
- YEARS 7 PREVIOUS YEARS 7*
Macroalgae Mid-depth No. of taxa yes yes Total biomass no discharge, FF:Op=Preep intake:Op< Preop, Community yes yes structure Deep No. of taxa yes yes Biomass no intake, discharge Op= Preop FF:Op< Preop Community yes yes structure Macrofauna Mid-depth No of taxa yes yes Total density no discharge, FF:Op= Preop intake:Op< Preop Community yes yes structure Deep No. of taxa yes yes ', yes Total density yes Community yes intake similar to structure recent years " Abundance, no. of taxa, biomass, total density, evaluated using ANOVA; community structure evaluated using numerical classification by year and station, b Operational period = 1990-1992 (August only)
- NF = nearfield FF = farfield TABLE 6-22.
SUMMARY
OF EVALUATION OF DETRITAL EFFECTS ON REPRESENTATIVE IMPORTANT BENTHIC SPECIES. SEABROOK OP2 RATIONAL REPORT, 1992. l NEARFIELD- l OPERATIONAL FARFIELD l PERIOD SIMILAR DIFFERENCES l AREA / DEPTH TO PREVIOUS CONSISTENT WII1 C0HHUNITY ZONE SPECIES YEARS?a PREVIOUS YEARS 7( Macroalgae mid-depth Easinaria digitata Op< Preop yes Laminaria yes yes l saccharina Hacrofauna mid-depth Poncogenela inermis no NF:Op= Preop l 1 FF:Op< Preop Modlolus codlolus Op< Preop yes Mytilidae yes yes Strongylocentratus yes yes droebachensis "Ce.nclusions derived from analysis of variance or nonparametric analyses. Operational period = 1991-1992. b NF = nearfield FF = farfield 6-60 l
HARINE MACROBENTHOS j 1 discharge (B19) and f arfield (D31) areas. Intertidal station in August was 'signifi-The of f-bottom location of the intake and cantly lower than previous years. This ; low velocity of water movement should not appears to be mainly a function of seasonal variation, as year-round biomass have an adverse effect on the benthos, There is no obvious explanation for the shows no change from previous years. Two change. The number of algal and macro- other species (Ampichoo rubricaca, faunal taxa, and algal and macrof aunal faminar14 digicaca) showed changes in the community composition showed no change nearfield area that were part of a long-during Seabrook Station operation (Table term trend that began prior to Seabrook 6-21). Station operation. At intake Station B16, a macroalgal and macrofaunal community structure during the operational period 6.4.3.3 lle.gp_Dinthic Community remained similar to previous years, but total biomass and abundance was signifi-The algal community in the deep zone cantly lower than previous years. There (nearfield stations B04 and B13, farfield is no obvious explanation for this trend. station B34) during the operational period Diver observations show no visible change was similar to previous years in terms of in the benthic community at the intake. community structure and numbers of taxa Additional monitoring should ascertain (Table 6-21) . Total biomass was signifi- whether this is part of natural varia-cantly lower at the farfield deep Station bility. All other aspects of the benthic ] B34, but was similar to previous years at community show no change that could be the deep discharge and intake stations, related to the operation of Seabrook Station. From 1990- 1992, the faunal community at the discharge and farfield stations in the deep zone showed similar community 6.5 LITERATURE CITEQ composition to all previous years. At the
- intake station, number of taxa, community Abbott , R.T. 1974. American seashells.
{ structure and total dennity showed no 2nd ed. New York: Van Nostrand Rein-dif ferences from the recent preoperational hold. period. Boesch, D.F. 1977. Application of l numerical classification in ecological
- 6.4.3.4 Effects of Seabroo}t Station investigations of water pollution. U.S.
Doeration Environmental Protection Agency, Ecological Research Report Agency, Most elements of the benthic community Scological Research Report, 114 pp. l structure and abundance or biomass of dominant species were similar to previous Bousfield, E.L. 1973. Shallow water l years, or if dif ferent, changes occurred gammaridean Amphipoda of New England. at both nearfield and farfield stations. Comstock Publishing, Ithaca, NY 312 pp. Total algal biomess at the nearfield 6-61
MARINE MACROBENTH0S Breen, P.A., and K.H. Mann. 1976. composition, distribution and zonation Changing lobster abundance and destruc- of seaweeds in the Great Bay estuary tion of kelp beds by sea urchins. Mar. system and the adjacent open coast of Biol. 34:137-142. New Hampshire. Bot. Marina 24:533-545. 4 Briscoe, C.S., and K.P. Sebens. 1988. Mathieson, A.C. and E.J. Hehre. 1986. ; Omnivory in Strongylocencrocus droe- A synopsis of New Hampshire seaweeds, bachlensis (Muller) (Echinodermata: Rhodora 88:1-139. Echinoidea): predation on subtidal mussels. J. Exp. Mar. Biol. Ecol. Menge, B.A. 1976. Organization of the 115:1-24. New England rocky intertidal community: role of predation, competition, and Franz, D.R. 1989. Population density and environmental heterogeneity. Ecol. demography of a fouling community Monogr. 46:355-393, amphipod. J. Exp. Mar. Biol. Ecol. 125:117-136. . 1979. Cetxistence between the seastars Astorias vulgarls and A. Gosner, K. L. 1978. A Field Guide to the forbes/l in a heterogeneous environment: Atlantic seashore. Houghton Mifflin a non-equilibrium explanation. Oecolo - Co., Boston, MA. 329 pp. gia. 41:245-272. , l Larson, B.R., R.L. Vadas, and M. Keser. . 1983. Components of preda-1980. Feeding and nutrition ecology of tion intensity in the low zone of the i the green sea urchin, Strongylocentrocus New England rocky intertidal region. i drosbachlensis in Maine, U.S.A. Mar. 0ecologia 58:141-155. l Biol. 59:49-62. l and J.P. Sutherland, 1976. Menge, B. Lubchanco, J. and B . A . Menge. 1978. Species diversity gradients: synthesis Community development and persistence of the roles of predation, competition in a low rocky intertidal zone. Ecol. and temporal heterogeneity. Am. Nat. Monogr. 48:67-94. 110:351-369. Mann, K.H., L.C. Wright, B.E. Welsford, Nair, K.K.C. and K. Anger. 1979. and E. Hatfield. 1984. Responses of Experimental studies on the life cycle the sea urchin Strongylocentrotus of Jossa falcata (Crustacea, Amphipoda). drosbachtensis (0.F. Muller) to water- Helgo. Wiss. Meeres. 37:444-452. borne stimull f rom potential predators and potential food algae. J. Exp. Mar. Normandeau Associates Inc. 1985. Sea-Biol. Ecol. 79:233-244, brook Environmental Studies. 1984 data report. Technical Report XVI-I. Mathieson, A.C., E.J. Hehre, and N, B. Reynolds. 1981. Investigations of New . 1989. Seabrook Environmental England marine algae. II: The species Studies. 1988. A characterization of 6-62
l HARINE MACRODENTIIOS baseline conditions in the Hampton- bathymetric distribution. Mar. Ecol. Seabrook area. 1975-1988. A preopera- Prog. Ser. 57:147-161. tional study for Seabrook Station. Technical Report XX-II. . 1991. Feeding ecology of benthic mobile predators: experimental
. 1990. Seabrook Environmental analyses of their influence in rocky Studies. 1989. A characterization of subtidal communities of the Gulf of baseline conditions in the Hampton- Maine. J. Exp. Mar. Biol. Ecol.
Seabrook area. 1975-1989. A preopera- 149:13-44, tional study for Seabrook Station. Technical Report XXI-II. Padmanabhan, M., and G.E. Hecker. 1991. Comparative evaluation of hydraulic 1991a. Seabrook Environ- model and field thermal plume data, mental Studies. 1990 Data Report. Seabrook Nuclear Power Station. Alden Technical Report XXII-I. Research Laboratory, Inc. 12 p.
. 1991b. Seabrook Environ- SAS Institute Inc. 1985. SAS User's mental Studies, 1990. A characteriza- Guide: Statistics, Version 5 edition.
tion of environmental conditions in the SAS Institute, Inc. Cary, N.C. Hampton-Seabrook area during the 956 pp. operation of Seabrook Station. Tech. Rep. XXII-II. Sebens, K.P. 1985a. Community ecology of vertical walls in the Gulf of Maine.
. 1992a. Seabrook Environ- USA: small scale processes and alterna-montal Studies ,1991. A characteriza- tive community states. In: P.G. Moore tion of environmental conditions in the and R. Seed (Editors). The Ecology of Hampton-Seabrook area during the opera- Rocky Coasts. Columbia Univ. Press, New tion of Seabrook Station. Tech. Rep. York, pp. 346-371.
XXIII-I.
. 1985b. The ecology of the
. 1992b. Seabrook Environ- rocky subtidal zone, a diversity of mental Studies. 1991 Data. Unpublished species on the limited space of subtidal Data Tables, rock. S. Am. Sci. 73:542-557.
. 1993. Seabrook Environmental Skutch, A.F. 1926. On the habits and Studies. 1992 Data. Unpublished Data ecology of the tube-building amphipod Tables. Ampichoe rubricaca. Montagu Ecology.
7:481-502. Ojeda, F.P. and J.H. Dearborn. 1989. Community structure of macroinverte- Sokal, R.R., and F.J. Rohlf. 1969. brates inhabiting the rocky subtidal Biometry. W.H. Freeman and Co. , San zone in the Gulf of Maine: seasonal and Francisco. xxi + 776 pp. 6-63
1 MARINE HACROBENT!!0S Taylor, W. R. 1952, Marine algae of the northeastern coast of North America. The University of Michigan Press, Ann Arbor Press. 509 pp. Teyssandier, R.G. , W.W. Durgin, and G.E. Hecker. 1974. Ilydrothermal studies of diffuser discharge in the coastal environment: Seabrook Station Alden Research Laboratory Report No. 86-24. Van Patten, P. 1992. Aliens among us. Nor' easter, magazine of the Northeast. Sea Grant Programs 4(2):8-13. Witman, J.D. 1985. Refuges, biological disturbance, and rocky subtidal commu-nity structure in New England. Ecol. Honog. 55(4):421-445.
. 1987. Subtidal coexistence:
storms, grazing, mutualism, and the zonation of kelps and mussels. Ecol. Honogr.' 55:421-445.
)
l l 1 l 1 6-64 i I I
4 TABLE OF CONTENTS PAGE 7.0 SURFACE PANELS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1 7.1 OBJECTIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1 7.2 HET110DS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1 7.2.1 Field Methods . . . . . . . . . . . . . . . . . . . . . . 7-1 7.2.2 Laboratory Methods . . . . . . . . . . . . . . . . . . . . 7-2 7.2.3 Analytical Methods . . . . . . . . . . . . . . . . . . . 7-2 7.3 RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 7.3.1 Short-Term Panels . . . . . . . . . . . . . . . . . . 7-3 7,3.2 Monthly Sequential Panels . . . . . . . . . . . . . . . . . 7-11 s 7.3.3 One Year Panels . . . . . . . . . . . . . . . . . . . . . 7-16 7.4 DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . 7-16 7.5 LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . 7-19 7-1
LIST OF FIGURES PAGE 7-1. Surface panel sampling stations . . . . . . . . . . . . . . . . . . 7-1 7-2. Monthly faunal richness (number of faunal taxa on two replicate panois) abundance, and biomass during the operational period (1991-1992) and in 1992 compared to means and 95% confidence limits on short-term panels at nearfield Stations B19 and B04 during preoperational period (1978-1984 and July 1986-December 1989) . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4 7-3. Log abundance (no. per panel) or monthly mean percent frequency of Mytilidae, Jassa marmorata, and Tubularia sp. on short-term panels at Stations B19 and B04 during the operational period l (1991-1992) and in 1992 compared to mean abundance.or percent frequency and 95% confidence limits during the preoparational period (1982-1984 and July 1986-December 1989) . . . . . . . , . 7-10 7-4. Mean biomass (g/ panel) and Mytilidae (percent frequency of occurrence) during the operational period (1991-1992) and in .,- 1992 compared to mean and 95%. confidence limits during the preoperational period (Stations B19 and B04 from 1978-1984 and July-December 1986-1989) on monthly sequential panels . . . . 7-12 7-5. Monthly mean percent frequency of occurrence on monthly sequential panels for Jassa marmorata, Balanus sp., and Tubularla sp. at Stations B19 and B04 during the operational period (1991-1992) and in 1992, compared to mean and 95% confidence limits during the prsoperational period (1982-1984 and July 1986-December 1989) . . . . . . . . . . . . . . . . . . . 7-15 1
'1 l
1
^
l 7-11
LIST OF TABLES PAGE 7-1. KEANS (PER/ PANEL) AND 95% CONFIDENCE LIMITS OF SELECTED PARAMETERS AND SPECIES ABUNDANCES AT STATIONS B19, B31, B04, AND B34 OVER THE PRE 0PERATIONAL PERIOD, AND 1992 AND OPERATIONAL PERIOD (1991-1992) MEANS . . . . . . . . . . . . . . . 7-5 7-2. RESULTS OF ANALYSIS OF VARIANCE COMPARING MORTHLY TOTAL NUMBER OF TAXA, NONCOLONIAL FAUNAL ABUNDANCE, TOTAL BIOMASS, AND SELECTED SPECIES ABUNDANCE OR PERCENT FREQUENCY ON SHORT TERM PANELS AT MID-DEPTH (B19, B31) AND DEEP (B04, B34) STATION PAIRS DURING PREOPERATIONAL (1978-1989) AND OPERATIONAL (1991-1992) PERIODS . . . . . . . . . . . . . . . . . . 7-6 7-3. ANOVA RESULTS COMPARING MONTHLY SEQUENTI AL BIOMASS AT HID-DEPTH (B19, B31) AND DEEP (B04, B34) STATION PAIRS DURING PREOPERATIONAL (1978-1989) AND OPERATIONAL (1991-1992) PERIODS . . . . . . . . . . . . . . . . . . . . . . 7-13 7-4. NEARFIELD/FARFIELD COMPARISON OF ANNUAL KEAN LENGTH (mm), AND STANDARD DEVIATION OF JASSA #ARNORATA AND MYTILIDAE SPAT COLLECTED IN 1992 ON MONTHLY SEQUENTIAL PANELS . . . . . . . 7-14 7-5. DRY WEIGHT BIOMASS, NONCOLONIAL NUMBER OF TAXA, ABUNDANCE, AND LANINARIA SP. COUNTS ON SURFACE FOULING PANELS SUB-MERGED FOR ONE YEAR AT STATIONS B19, B31, B04, AND B34 ; DURING THE PREOPERATIONAL PERIOD (1982-1984 AND 1986-1989), l 1992, AND THE OPERATIONAL PERIOD (1991-1992) . . . . . . . . . . . 7-17 i 7-6.
SUMMARY
OF EVALUATION OF DISCHARGE PLUME EFFECTS ON THE i FOULING COMMUNITY IN VICINITY OF SEABROOK STATION . . . . . . . . . 7-18 I i l 1 1 j l l 7-111 j J
SURFACE PANELS 7.0 SURFACE PANELS 7.2 METHODS 7.1 OBJECTIVES 7.2.1 Field Methods The surface fouling panels program was Fouling panels (10.2 cm x 10.2 cm rough-designed to study both settlement patterns ened plexiglass plates) were collected and community development in the discharge monthly from January through December at plume area and in corresponding f arfield two mid-depth stations (nearfield B19, a r e'a s . Short-term panels, submerged for depth 12.2 m and f arfield B31, depth 9.4 one month, provide information on the m) and two deep stations (nearfield B04, temporal sequence of settlement activity, depth 18.9 m and farfield B34, depth 21 while monthly sequential panels, exposed m; Figure 7-1). Collections were made at from one to twelve months, provide Stations B04, B19 and B31 from 1978 to information on growth and successional 1984, at Station B34 from 1982 to 1984, patterns of community structure. and at all stations (B04, B19, B31 and N "rE W G'
~~
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f Figum 71. Surface panel sampling stations. Seabrook Operational Report,1992. 7-1
4 SURFACE PANELS B34) from July 1986 to 1992. Panel depths not quantified) when found in the sample, below the water surface ranged from 3 to but not directly on the panel face. For 6 m depending on the tidal stage. MS panels, the percent frequency of occurrence of selected dominants (colonial Two dif forent panel types were employed and noncolonial), and diatom and macroal-at each station: short-term (ST) panels, gal species were estimated using the exposed for one month, and monthly procedure outlined above. Counts were sequential (MS) panels, exposed for estimated for noncolonial species and an increasing time periods f rom 1-12 months. abundance class was recorded. Colonial Two replicate short-term panels and one and noncolonial dominants, diatoms, and monthly sequential panel were collected macroalgae were recorded as "P" (present, monthly at each of the four stations. In but not quantified) when found in the December, an additional MS panel was sample, but not directly on the panel collected at each station. face. Random samples of 1200 Mytilidae and 7.2.2 Laboratory Methods 1100 Jassa marmorata individuals were measured and recorded in 0.1 mm increments In the laboratory, each panel was (NAI 1990). All Jassa marmoraca and dismantled and the panel face photo- Mytilidae individuals less than 1.0 mm _ graphed. The fouling material was scraped were recorded as <1.0 mm and estimated at off the wood block and panel support 0.5 mm in calculations of mean lengths. apparatus, and rinsed over a 0.25 mm mesh _ sieve prior to storage or processing. The Dry-weight biomass from one of each pair uood blocks f rom all MS panels were dried, of ST replicates and all MS panels was split, and examined for the presence of determined after taxonomic processing by wood-boring organisms. drying all faunal and floral material to a constant weight at 105'C. All noncolonial species collected monthly on both ST replicates and one December MS replicate were identified and 7.2.3 Annivtical Methods enumerated. When high abundances of Mytilidae, #1 ace 11a sp and Anomla sp. oc- Analysis of Variance curred, organisms were enumerated f rom subsamples generated using a Folsom The intensity of recruitment on ST plankton splitter (NAI 1990). Colonial panels, measured by the number of all animals, diatoms and macroalgae were taxa, the abundance of noncolonial or-quantified by determining the percent ganisms, and biomass, gives an indication frequency of occurrence on the panel face of the potential for fouling community (Mueller-Dombols and E11enberg 1974; development. Monthly biomass levels on i Rastetter and Cooke 1979; NAI 1990), monthly sequential panels give an indica-Colonial animals, diatoms, and macroalgal tion of observed community development. species were recorded as "P" (present, but Multiway analyses of variance (variables 7-2
SURFACE PANELS Preop-Op, Year, Station and Month) were 7.3 EESULTS used to compare community potential (as exemp?ified by species richness, abun- 7.3,1 Short-Term Panels dance, biomass and selected dominant species) as well as community development Short-term panels provide information (biomass) between preoperational (general- on the seasonal cycles of settlement ly 1978-1984 and 1986-1989) and operation- activity. Seasonal cycles in faunal ; al (1991-1992) years at paired nearfield richness in 1992 and during the opera-(B19, D04) and farfield (331, B34) tional period were similar to historical stations. Log-transformed monthly mean preoperational trends. In 1992, as in the values were used for short-term preoperational years, the number of taxa noncolonial total abundance and all increased in June and remained high selected species abundances (Jassa through September at both B19 and B04 aarmorata and Mytilidae), or frequency of (Figure 7-2). The number of taxa was occurrence (Tubularla sp. ) in the ANOVAs. higher than average in 1992 than in Non-transformed monthly mean values were preoperational years (Table 7-1), a trend used in the multiway analyses of variance that also occurred in 1991 (NAI 1992), for short-term and monthly sequential The average number of taxa during the biomass and short-term number of taxa. operational period was significantly A significant difference in the interac- higher than the preoperational average at tion (Preop-Op X Station) was investigated all four stations (Table 7-2). Signifi-by comparing the least square means with cant differences were also noted among a paired e-test (SAS 1985). months and years. The seasonal pattern of faunal abur.aance t Test during the operational years was also l similar to that of preoperational yes.:s. Community development was also assessed During 1991 (NAI 1992) and 1992, abundanc-by examining biomass, species richness, es remained low from January to May and and abundance on surface panels exposed then increased in June and July, consis- : for one year. Biomass, species richness, tent with previous years (Figure 7-2). l and abundance were each compared between A second, less-intense abundance peak oc-preoperational (generally 1982-1984 and curred in September at both B04 and B19 1986-1989) and operational (1991-1992) in 1992. ANOVA results showed significant periods at each station using c tests dif ferences among years and months (Table ! (Sokal and Rohlf 1969). Selected dominant 7-2). Although annual mean abundances in l species (Mytilidae and Jassa marmorata) 1992 were lower than the preoperational ) lengths were also compared using c tests mean abundance from May to December at ! to determine if average annual lengths Station B04 (Figure 7-2), there was no varied between nearfield and farfield significant difference between the opera-station pairs in 1992. tional and preoperational mean abuedance at this station or its f arfield counter- j part (B34; Table 7-2). The seasonal i 7-3
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f }. i i i i i i i i i i i i i i i -i iiiiiiii JAN ES MAA AML MAY AlN E AUO SEP OCT NOV DEC JAN PES MAA APR MAY TN E AUG SEP OCT NOV DEC MONTil MONTH Log (x+1) Abundance Station Big Station B04 4- 4- P=pmc a Popmu.a
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IA*f PE8 MAA APR MAY JUN JUL AUG SEP OCT NDY DEC JAN PER MAA APR MAY JUN E AUO 3EP OCT NOV DEC MONTH MONTil Figure 7 2. Monthly faunal richness (number of faunal taxa on two replicate panels) abundance, ! and biomass during the operational period (1991-1992) and in 1992 compared to ' means and 95% confidence limits on short-term panels at nearfield Stations B19 and B04 during preoperational period (19781984 and July 1986. December 1989). Seabrook Operational Report,1992. 7-4
,mi--r TABLE 7-1. MEANS (PER/ PANEL) AND 95% CohrIDENCE LIMITS OF SELECTED PARAMETERS AND SPECIES ABUNDANCES AT STATIONS B19, B31, B04, AND B34 OVER THE PREOPERATIONAL PERIOD, AND ;
1992 AND OPERATIONAL PERIOD (1991-1992) MEANS. SEABROOK OPERATIONAL REPORT, 1992. PREOPERATIONAL YEARSh 1992 _QE PANEL" PARAMETER / TAXON TYPE STATION LCL i* UCL i* ic Total no. of taxa ST B19 9.0 11.3 13.6 14.3 14.8 , , B31 8.9 10.8 12.6 13.2 13.0 B04 8.0 10.2 12.5 11.7 12.5 B34 9.7 11.7 13.7 11.7 13.0 Total noncolonial ST B19 36.9 55.4 83.1 43.4 56.9 abundance B31 43.8 71.2 115.4 31.3 40.6 B04 23.6 35.9 54.5 18.4 31.1 B34 20.5 41.2 81.9 13.3 32.7 Total biomass ST B19 0.6 0.8 1.1 0.4 0.7 (g) B31 0.3 0.6 1.0 0.3 0.3 s B04 0.4 0.6 0.9 0.1 0.5 7" B34 0.6 1.0 1.5 0.1 0.5 Mytilidae ST B19 33.4 34.0 34.6 114.7 26.3 B31 42.4 43.1 43.8 138.9 16.9 B04 20.7 21.2 21.7 32.5 13.9 B34 21.8 23.0 24.2 12.8 11.9 Jassa marmorata ST B19 3.1 3.4 3.7 6.1 2.1 B31 4.0 4.4 4.8 2.2 2.1 B04 2.2 2.6 3.0 0.2 1.1 B34 2.1 2.4 2.7 0.8 1.7 Tubularia spp. ST B19 1.6 2.1 2.6 13.2 1.6 B31 0.7 1.2 1.7 8.3 0.3 B04 1.2 1.6 2.0 2.5 1.4 B34 2.0 2.8 3.6 0.1 0.8 i Biomass MS B19 59.0 207.8 356.6 86.5 174.7 (g) B31 93.7 236.8 379.9 193.1 180.8 B04 41.5 203.1 364.8 103.7 139.9 B34 54.1 199.6 345.1 176.9 223.5
*ST = short term MS = monthly sequential b
Preoperational = 1978-1984 first sampled in 1982
*Geometricmeanfortotalabu.Jul1986-Dec1989exceptB34,whichwas ndance, and Mytilidae and J. marmorata abundance Percent frequency of occurrence for Tubularia sp. Preop. and Op. means are means of annual means.
_ _ _ _ _ _ _ - - _ . _ = -_
TABLE 7-2. RESULTS OF ANALYSIS OF VARIANCE COMPARING MONTHLY TOTAL NUMBER OF TAXA, NONCOLONIAL FAUNAL ABUNDANCE, TOTAL BIOMASS, AND SELECTED SPECIES ABUNDANCE OR PERCENT FREQUENCY ON SHORT TERM PANELS AT HID-DEPTH (B19, B31) AND DEEP (B04, B34) STATION PAIRS DURING PREOPERATIONAL (1978-1989) AND OPERATIONAL (1991-1992) PERIODS. SEABROOK OPERATIONAL REPORT, 1992. SOURCE OF MULTIPLE PARAMETER 5faIIONS VARIATION df SS Ff COMPARISONS 9 (ranked in decreasing order) Total number of taxa B19, B31 Preop-Op* 1 330.20 49.93*** Op> Preop Year (Preop-Op)b 11 1,898.31 26.10*** Month 136 10,155.23 11.29*** Station(fear) 1 45.28 6.85** Preop-Op'X Station
- 1 16.79 2.54 NS y Error 144 952.23 B04, B34 Preop-Op 1 278.21 46.47*** Op> Preop !
11 1,291.66 19.61 NS Year Month(Preop)-Op) (Ycar 136 7,288.89 8.95*** Station 1 0.49 0.08*** Preop-Op X Station 1 5.43 0.91 NS Error 100 598.67 Noncolonial faunal B19, B31 Preop-Op 1 0.44 4.51* abundance Year (Preop-Op) 11 17.68 16.59*** Pre Op Pre Op Month (Year) 136 265.98 20.19*** B31 B19 B19 B31 Station 1 0.00 0.05 NS Preop-Op X Station 1 0.60 6.17* Error 144 13.95 B04, B34 Preop-Op 1 0.09 1.15 NS 11 15.75 17.49*** Year Month(Preop)-Op) (Year 136 294.54 17.48*** Station 1 9.00 0.01 NS Preop-Op X Station I L 01 0.12 NS Error 100 3.18 (continued)
TABLE 7-2. (Continued) SOURCE OF MULTIPLE PARAMETER STATIONS VARIATION df SS F f COMPARISONS 9 (ranked in decreasing order) Biomass B19, B31 Preop-Op 1 2.69 2.82* Op< Preop Year (Preop-O 9 18.40 2.15* Month (Year) p) 114 296.11 2.73*** Station 1 3.41 3.58* Preop-Op X Station 1 0.46 0.49 NS Error 122 116.10 Y
" B04, B34 Preop-Op 1 4.49 6.14* Op< Preop Year (Preop-Op) 9 25.36 2.82***
Month (Year) 114 491.74 5.89*** Station 1 1.01 1.38 NS Preop-Op X Station 1 1.92 2.62 NS Error 100 73.18 Mytilidae B19, B31 Preop-Op 1 2.13 17.78*** Year (Preop-O 11 22.47 17.05*** Pre Op Op Pre Month (Year) p) 136 327.27 20.09*** B31 B31 B19 B19 Station- 1 0.06 0.54 NS Preop-Op X Statior 1 0.83 6.95** Error 144 17.25 B04, B34 Preop-Op 1 1.62 17.95*** Op< Preop Year (Preop-O 11 19.28 19.45*** Month (Year) p) 136 227.46 18.55*** Station 1 0.04 0.41 NS Preop-Op X Station 1 0.04 0.43 NS Error 144 9.01 (continued) - _ - _ _ _ _ _ = - . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . - - - - _ _ _ _ _ _ _ _ _ _ _ _ -_. __ _ . - _ __ . - - _ _ _ _ _ _ _ _ _ _ _
TABLE 7-2. (Continued) SOURCE OF MULTIPLE PARAMETER' STATIONS VARIATION df SS Ff COMPARISONS 9 (ranked in decreasing order) Jassa marmorata B19, B31 Preop-Op 1 1.37 13.61*** Op< Preop Year (Preop-Op) 11 6.80 6.13*** Month (Year) 136 96.72 7.05*** Station 1 0.05 0.52 NS Preop-Op X Station 1 0.08 0.78 NS Error 144 14.52 B04, B34 Preop-Op 1 0.69 6.10* Op< Preop Year (Preop-Op) 12 8.53 6.90*** Month (Year) ?36 63.49 4.15*** Station 1 0.00 0.04 NS Preop-Op X Station 1 0.33 2.97 NS
~a Error 144 11.24 Tubularia sp. B19, B31 Preop O 1 0.83 5.31* Op< Preop Year (P eop-O 11 9.80 5.71***
Month (Year) p) 136 95.93 4.52*** Station 1 1.71 10.94** Preop-Op X Station 1 0.28 1.78 NS Error 144 22.49 B04, B34 Preop-Op 1 0.46 4.78* Op< Preop Year (Preop-Op) 11 11.86 11.19*** Month (Year) 136 98.76 7.53*** Station 1 0.11 1.19 NS Preop-Op X Station 1 0.17 1.76 NS Error 144 9.64
" Preop-Op = 1991 and 1992 v. previous years (1978-84; July 1986-December 1989 except B34, which began in 1982) regardless of station b Year nested within preoperational and operational periods regardless of station
- Month nested within year regardless of station dStationfregardless of year or period
" Interaction between main effects Station and Preop-Op
'NS = Not significant (p20.05)
* = Significant (0.052p>0.01)
** = Highly significant-(.012p>0.001)
*** = Very. highly significant (0.0012p) 80nderlining indicates no significant differences (a 5 0._05) in least square means using a paired t test.
F
SURFACE PANELS pattern at Station B19 in 1992 was similar operational average, however, occurred in to both 1991 and the preoperational period August, approximately one month earlier (Figure 7-2; NAI 1992). Operational abun- than in preoperational year au to the dances were significantly lower than seasonal trend in 1991 (NAI " .s2) . ANOVA preoperational abundances at farfield results indicated that although the Station B31, but the operational and biomass levels at both Stations B04 and
. preoperational mean abundances at Station B34 were significantly lower during the B19 (located within the discharge plume) operational period than in preoperational were not significantly different (Table years, the levels were not significantly 7-2). different between the two stations.
Seasonal settling patterns for the Several dominant taxa on short-term entire fouling community (motile fauna, panels were monitored to determine their colonial organisms, macroalgae) are best long-term recruitment patterns. Mytilidae demonstrated by changes in biomass. The spat (mainly #ytilus edu11s) was the most seasonal trend in total biomass at near- abundant noncolonial taxon. In opera-field Station B19 in 1992 and in opera- tional and preoperational years, settle-tional years was sinilar to historical ment occurred throughout the year, but was observations. In 1992, the highest most intense from June through September biomass at B19 occarre6 in September (Figure 7-3), coincident with larval (Figure 7-2), coincident with high numbers availability (Section 4.0) . In 1992, peak of bivalves (Mytilidae (Figure 7-3), and settlement occurred in July at both B19 Anocla sp. and Elatella sp. (NAI 1993)) and B04, and then decreased in August at and high percent cover of the hydroid Station B04, but rebounded in September Tubularla sp. (Figure 7-3). Seasonal at B19. The operational mean was rignifi-trends were substantiated by a significant cantly higher than the preoperational mean dif ference among months (Table 7-2). Peak at Stations B04 and B34, but there was no biomass at B19 in 1992 was less than that significant difference between the near-observed in 1991 (NAI 1992) and during the field-farfield station pair (Tables 7-preoperational period (Figure 7-2), al- 1,2). The preoperational and operational though B19 was not significantly different mean abundances of Mytilidae at nearfield f rom its f arfield counterpart B31 (Table Station B19 were not statistically 7-2). The biomass levels in 1991 at B19 different, but the operational mean were not significantly different from abundance at Station B31 was significantly preoperational levels (NAI 1992), indicat- lower than the preoperational mean (Table ing that the low biomass levels in 1992 7-2). Significant differences were also were responsible for the signiticent noted among years and months. difference between operational (1991-1992) and preoperational years (Tables 7-1,2). The amphipod Jassa marmoraca (formerly At B04, biomass did not show a marked sea- known as J. falcata) is a common fouling sonal increase in 1992. Blomass levels organism (Nair and Anger 1980). This were consistently low throughout the year species lacks a larval stage, so re-(Figure 7-2). The peak period of the cruitment occurs through dispersal of 7-9
.- - ,~ ..
Mytilldre Station B19' Station B04 4- Pr.op..amn +- er.op nm i
.......... opaging .......... Op.aum4
. ---o-- iw2 g ---o-- tw2 ys- -
g s- ;'..., 1-
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- i i i i i i i i i ii a i i i r iiiiiii JAN PE8 MAR APR MAY JUN Ali. ADO SEP OCT NOV DEC JAN Pli8 MAR AIR MAY JUN JUL AUG SIIP OCT NOV DEC MONTil MONT11 Jassa marmorata Station B19 Station B04 4- er , pow.i 4- preop.uimit op %a .......... op mg
. ---o--- tw2 0 - - -o - - in2 y s- 5 1-2 a
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'~)f . / I.-i lo':vlo,'N=A- IT i i i i i e JAN FE8 MAR AIR MAY JUN JUL AUC SEP OCT NOV DEC JAN FE8 MAR APR MAY JUN AL AUG SEP OCT NOV DEC MONTli . MONTil r
Tubularia sp. Station B19 Station B04 im - Pr.opmuma , im - pr.opma=4 go ----** Operanmal 61 go - .......... O, im4 g --o-- in2 l'.,) ,_ - - -o - - iw2 C "- [ $s . U "- G eo - I \\ b eo - , u 's u - o m-g
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i __ ,i, i iiiiiii JAN FEB MAR Alt MAY JUN JUL AUG SEP OCT NOV DEC
, i i , i JAN PE8 MAR APR MAY JUN RL AUG SEP OCT NOV DEC .
i c MONTil MONTil
.i l
i Figure 7-3. Log abundance (no. per panel) or monthly mean percent frequency of Mytilidae, , lassa marmorata, and Tubularia sp. on short term panels at Stations B19 and _
- B(M dudng the opemtional period (1991-1992) and in 1992 compared to mean abundance or percent frequency and 95% confidence limits during the preoperational period (1982-1984 and July 1986. December 1989). Seabrook Operational Report.1992.
i 7-10 l r ..,n - <, - , , v. . .- - , -
~ _ . _ _ _ _ _ , - . _
l 1 SURFACE PANELS I
.l 1
juveniles or adults through the water differences were also noted among years column (Bousfield 1973). In 1992, J. and months (Table 7-2), warmorata abundances were low throughout I ths year at Station B04. At Station B19, ; J. marmorata abundances were low from 7.3.2 Honthly Secuential Panels Janucry to July but approximated the abundances of operational and preop- Monthly sequential panels provide erational years from August to November information on growth and successional-(Figure 7-3). Although ANOVA results patterns of development within the fouling indicated densities were significantly community. As in the short-term program, lower at all stations during the opera- seasonal patterns of community development tional period than in preoperational were assessed by examining the monthly years, there were no significant differ- biomass levels. The seasonal biomass ences between nearfield-f arfield station pattern and monthly means in 1992 were pairs (Tables 7-1,2). Significant similar to preoperational years at Station differences were also noted among years B04 (Figure 7-4). Biomass levels remained and months (Table 7-2). low through June, then increased steadily, peaking in October. At Station B19, the The hydroid Tubularia sp. is a dense 1992 biomass levels also remained low summer colonizer. It is important because through June, but the increase initiated of its voluminous growth habits, which can in July was not maintained through the provido a substrate (Field 1982) and food following months. Seasonal differences source (Clark 1975) for epifaunal taxa. were underscored by a significant differ-In previous years, Tubularla sp. reached ence among months. Despite the observed peak cover between July and September (NAI fluctuations, there was no significant 1992). At Station B04, the peak percent difference between operational and cover occurred one month later in 1992 preoperational means at any of the (September) than in 1991 (NAI 1992), but stations (Table 7-3). was coincident with the preoperational peak (Figure 7-3). At Station B19, the Seasonal patterns of community dominants peak percent cover occurred in September, in 1992 were similar to those observed as in 1991 and preoperational years during the preoperational period in most (Figure 7-3, NAI 1992). Also, the percent cases. Mytilidae spat settled heavily on frequency in 1992 was less than in panels in July at both nearfield stations preoperational years during all months, (Figure 7-4). As in previous years (NAI except September at Station B19 (Figure 1986; 1988a; 1988b; 1991a; 1991b), fre-7-3). The operational mean percent quency of occurrence remained near 100% > frequency was significantly lower than the in 1992 and was higher than the preopera-l preoperational mean at all four stations, tional mean for the rest of the year, but there was no significant difference except December. Mytilidae spat measure-between the nearfield-farfield station ments from monthly sequential panels in , pairs (Tables 7-1,2). Significant 1992 were compared to determine if mean l 1engths differed between nearfield-far- ! 7-11 1
)
Biomass Station B19 Station B04 11M - Praymuma tim - %,uma imo . .......... op uma ; tom - opmumal
- - .o -
--4-- 1992 1992 ..
l . u- "- 3 ./ 4 g m- l [*- A b a- l b a- j \, 3 m- ! E m- !\ s. e m , 1 x o a-a
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, , , , i w na Maa a m m .u. Auo e oCr ecv Dac w na x^a a = = am ^m e ocr e onc MONT11 MONTil Mytilidae Station B19 Station B04 Pm9 mum 41 p,,,,g ,g OPmumai ,,,,,,,,,-
Opmdm4 n
,,_ -"".o""-
1992 fr:,-{,, 1# -
~~4-- ',n- o ~q p,
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1992 so - ' lV '. b .
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m. l g 1 i 10 - 0 10 - / i I 0- r~ - $- i i i I 1 i i 3 0 JAN ftB MAA AML MAY A/N NL AUG W OCT Nov DEC JAN R3 MAR APR MAY A.'N AL AUG W OCT NOV DEC MONril MONTil Figurt 74. Mean biomass (g/ panel) and Mytilidae (percent frequency of occunence) during the operational period (1991-1992) and in 1992 compared to mean and 95% confidence j limits during the preoperational period (Stations B19 and B04 from 1978-1984 and
- l. July-December 1986-1989) on monthly sequential panels. Seabrook Operational Report,1992.
7-12
f l
- SURFACE PANELS TABLE 7-3. ANOVA RESULTS COMPARING HONTHLY SEQUENTIAL BIOHASS AT HID-DEPTH (B19, B31) AND DEEP (B04, B34) STATION PAIRS DURING PREOPERATIONAL (1978-1989) AND OPERATIONAL (1991-1992) PERIODS.
SEABROOK OPERATIONAL REPORT,1992. SOURCE OF STATIONS VARIATION df SS Ff Mid-depth Preop-Op* 1 2,563.6 0.21 NS B19, B31 Year (Preop-Op)b 11 3,261,845.6 24.55*** Station 1 1,961.2 0.16 NS Month (Year)d 124 14,793,972.2 9.88*** Preop-Op X Station' 1 22,263.4 1.84 NS Error 134 1,618,554.9 Deep Preop-Op 1 3,506.1 0.25 NS B04, B34 Year (Preop-Op) 11 3,035,891.9 20.05*** Station 1 128,822.3 9.36** Month (Year) 124 14,973,971.1 8.77*** Preop-Op X Station 1 21,823.3 1.59 NS Error 100 1,376,539.3
- Preop-Op = 1991 and 1992 v. previous years (1978-84; July 1986-December 1989 except B34, which began in 1982) b Year nested within preoperational and operational periods regardless of station
- Station regardless of year or period d
Month nested within year regardless of station
- Interaction between main effects NS = Not significant (.05>p)
* = Significant ( . 01<p.4. 05 )
** = Highly significant (.001<ps.01)
*** = Very highly significant (ps.001)
I l l 7-13
SURFACE PANELS I field station pairs. Mytilid annual mean lower from October to December (Figure 7- l 1engths ranged fr'om 1. 7 to 4.3 mm in 1992 5). At Station B19, percent frequencies at all four stations (Table 7-4). Annual in 1992 were low from January to July and averages of Mytilidae spat lengths were higher than preoperational values from not statistically different between near- August to November. The monthly opera-field and farfield station pairs B19 and tional mean percent frequencies approxi-B 31 ( t=0.12, t.1ph.=o.ot ,n=21 = 2. 80) and B04 mated those of the preoperational period, and B34 (t=0.86, t,gpg,,o,og,n,3, = 1.15 ; Average lengths of Jassa marmorata Sokal and Rohlf 1969). individuals colonizing monthly sequential panels ranged from 3.1 to 5.0 mm in 1992 In 1992, Jassa marmorata percent fre- (Table 7-4). A c test indicated that quencies remained low at Station B04 there were no significant differences throughout the year. The operational between lengths at nearfield-farfield average percent frequency approximated station pairs B19 and B31 (t=0.15, that of the preoperational period from t 1ph.=o.ot.n=la = 2.85) or B04 and B34 January through September, but was much ( t=1. 00, t.1ph.=o.ol,n= t1 = 1.06; Sokal and Rohlf 1969). TABLE 7-4. NEARFIELD/FARFIELD COMPARISON OF ANNUAL MEAN LENOTH (mm), AND STANDARD DEVIATION OF JASSA #ARNORATA AND HYTILIDAE SPAT COLLECTED IN 1992 ON HONTHLY SEQUENTIAL PANELS. SEABROOK OPERATIONAL REPORT, 1992. SPECIES 1992 B19 B31 B04 B34 Mytilidae spat Mean 1.7 2.6 4.3 3.8 SD 1;36 2.28 4.16 4.48 Jassa marmorata Mean 5.0 3.6 3.1 3.4 SD 1.06 1,79 1.08 1.11 In 1992, Balanus sp. (including Balanus occurred in September 1992 at B04, one spp. and Semlbalanus balenoides) appeared month later than that of the second at nearfield stations (B04 and B19) in preoperational average peak. Frequencies ; April, similar to previous years (Figure decreased markedly from September to 7-5). As in preoperational years, peak November at B19 and October to December frequency in 1992 occurred in July at B19. at B04, although percent frequencies at At B04, peak frequency in 1992 also B04 remained above the preoperational occurred in July, one month later than the mean, preoperational average. A second peak 7-14
Jtssa marmorata St: tion B19 Stztion B04 im - rr pm6ma im -
%%i
.......... Opereumal ........ *
,o - , so Opened ,
--o-- IM2 , g ,
--.o-- 1992
> M- s 9 t ; e' \ 4 >M-f Q O. U 6 e- lg s l 6 m-o $o - l
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i i '- Y i i i r1- Y- r- r^?--?--?- 1 lAN IRB MAR Am MAY EH jut. ADO SEP OCT NOV DEC JAN fEB MAR Am MAY LH JUL AUG SEP OCT NOV DSC HONT11 MONT11 Balanus sp. Station B19 Station B04 ; 1 Pmoperational Prooperatimal ) opmo.a , , , opmo..i i= == --.e-- ,9 --o-- in2 in2 i
- w. is n-
=- 9' /., a-9.
n- l l . , ' C a-"- W >
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a f l y GQ o -i i [' , j , , , 1-yy- , r i i r- Y i i i t- Y-JAN IES MAR Am MAY LW L't. AUG SEP OCT N0Y DEC JAN FEB MAR Am MAY LH kt AUG $EP OCT NOV DEC MONT11 MOWI Tubularia sp. Station B19 Station B04 loo - Wumd 1" - W hd j
,o - ..........
opmu a ,o - .......... opmo g ,, ;
- - .0- -
1992 - 4-- 1992
,, ,, /' 3
,8 i D*, %- ! \
6 w-D 6 so - - Il n i t o 50 - o so - .
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W g W i i [ ] & 40 -- g E 40 -- . l l 4 ' i s .
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i r JAN fE3 MAR Am MAY LH At AUG 1EP OCT NOV DEC JAN REB MAR Am MAY JUN Lt AUG 3EP OCT NOV DEC MONT11 MONT11 i i 1 l l l Figure 7-5. Monthly mean percent frequency of occurrence on monthly sequential panels . forJussa marmorata, Balanus sp., and Tubularia sp. at Stations B19 and l B04 during the operational period (1991-1992) and in 1992, compared to mean i and 95% confidence limits during the preoperational period (19821984 and July l 1986. December 1989). Seabmolc Operational Report,1992. 7-15
SURFACE PANELS In 1992, the appearance of Tubularla sp. In 1992, as in 1991, no Laninaria sp. was delayed until' August at both nearfield occurred on the one-year panels at near-stations (B04, B19, Figure 7-5). The peak field Station B04, consistent with the percent frequency occurred in September preoperational period. No significant at both nearfield stations. The percent differences were noted between the oper-frequency of Tubularia sp. at Station B04 ational and preoperational periods at any was higher than the preoperational average of the stations (Table 7 5). In September, and lower than average for the rest of the year. At Station B19, Tubularla sp. frequencies were comparable 7.4 DISCUSSION to preoperational years (Figure 7-5). The surface panels program was estab-lished to document the temporal and 7.3.3 One Year Pash spatial patterns in the recruitment and development of the fouling community and Community development was also assessed to monitor the effects of Seabrook by examining biomass, species richness and Station's operation. The characteristics abundance on surface panels exposed for of Seabrook Station's thermal plume have one year. Year-end biomass values in 1992 been estimated from hydrothermal modeling and for the operational period were not studies (Teyssandier et al. 1974) and significantly different from preopera- confirmed on recent field studies (Pad-tional means (Table 7-5). manabhan and Heckler 1991). Results from field studies generally confirmed initial As in 1991, the number of noncolonial model results, indicating that the taxa collected in 1992 was higher than the discharge plume area was relatively small preoperational average at all stations under the conditions tested. For example, collected (Table 7-5). This difference the isotherm of a surface temperature was significant at Station B19 (1991 only) increase of 3*F (1.7'C) covered a rela-and at Station B31 (both in 1992 and for tively small 32 acre area in the vicinity the operational period). There was no of the discharge area. significant difference at either B04 or B34. The community settling and developing. on surface panels has shown predictable In 1992, the noncolonial abundance was seasonal patterns throughout the study. higher than the preoperational mean Most differences noted in 1992 occurred abundance at Station B31, but was lower at both the nearfield stations and their , at both B04 and B34 (Table 7-5). The farfield counterparts, indicating that the operational mean abundance was signifi- differences were part of a regional trend cantly higher than the preoperational mean (Table 7-6). In four cases, noncolonial i at Station B31, but there was no signifi- and Mytilidae abundances on short-term l cant difference at the other stations. panels, and number of taxa and non-colonial abundance on monthly sequential panels, variability occurred during the 7-16 ;
SURFACE PANELS TABLE 7-5. DRY WEIGHT BIOHASS, NONCOLONIAL NUHBER OF TAXA, ABUNDANCE, AND EANINeRIA SP COUNTS ON SURFACE FOULING PANELS SUBHERGED FOR ONE YEAR AT STATIONS B19, B31, B04, AND B34 DURING THE PREOPERATIONAL PERIOD (1982-1984 AND 1986-1989), 1992, AND THE OPERATIONAL PERIOD (1991-1992) . SEABROOK OPERATIONAL REPORT,1992. PREOPERATIONAL OPERATIONAL STATION HEAN S.D. 1992* MEAN BIOMASS B19 661.5 476.88 __ 1056.2 NS (g/ panel) B31 708.9 523.86 624.1 674.8 NS B04 600.9 474.66 169.3 398.4 NS B34 823.2 570.39 889.6 1013.1 NS NUMBER OF NON- B19 21.3 4.42 __ 33.0
- COLONIAL TAXA (No./ panel) B31 25.9 4.60 42 42.0
- B04 23.6 4.16 30 31.5 NS B34 22.9 5.05 47 41.5
- NONCOLONIAL 819 13,905.1 7,046.48 __
14,132 NS ABUNDANCE (No./ panel) B31 21,967.6 18,398.27 54,149 58,381.5
- B04 19,386.0 15,063.89 8,160 17,800.0 NS B34 19,221.7 19,986.38 15,182 25,307.0 NS EANINARIA SP. B19 24.3 36.91 __ 0 NS (No./ panel)
B31 39.3 29.24 15 11.5 NS B04 14.1 34.40 0 0.0 NS B34 15.9 26.83 1 0.5 NS l
- 01<ps.05 when preoperational and operational means tested with a single sample e test (Sokal and Rohlf 1969)
"All station B19 panels lost in a winter storm, December 1992. 7-17
SURFACE PANELS TABLE 7-6.
SUMMARY
OF EVALUATION OF DISCHAR0E PLUME EFFECTS ON THE FOULINO COMMUNITY IN VICINITY OF SEABROOK STATION. SEABROOK OPERATIONAL REPORT, 1992. OPERATIONAL PERIOD SIMILAR TO NEARFIELD-FARFIELD DEPTH PREVIOUS DIFFERENCES CONSISTENT b YEARS 7 WITH PREVIOUS YEARS 7* COMMUNITY ZONE" PARAMETER Fouling community: Mid-depth Abundance no NF:Op=Proop FF:Op< Preop Settlement d No. of taxa Op>Proop yes Biomass Op< Preop yes Deep Abundance yes yes No. of taxa Op> Preop yes Blomass Op< Preop yes Fouling community: Mid-depth Abundance no RF:Op= Preop FF:Op>Proop d Op> Preop yes Development No. of taxa Biomass yes yes Deep Abundance yes yes No. of taxa no NF:Op= Preop FF:Op> Preop Biomass yes yes Fouling community Mid-depth Myt111dae no RF:Op= Preop FF:Op< Preop Hettlement d Deep Op< Preop yes Mid-depth Jaasa Op< Preop yes Deep marmorata Op< Preop yes Mid-depth Op< Preop yes Deep Inhulatia sp. Op< Preop yes
- Mid-depth = Stations B19, B31. Deep = Stations B0a, B34 b Abundance, number of taxa, biomans, and total density evaluated using ANOVA, or e test NF = nearfield FF = farfield d Settlement = short term panels; Development = MS panels 7-18
SURFACE PANELS operational period that was restricted to ization of baseline conditions in the the farfield stat' ions. Since there were Hampton-Seabrook area. 1975-1987. A no significant differences between preoperational study for Seabrook Station. Technical Report XIX-II. preoperational and operational years at nearfield Stations B19 or B04 (Table 7-2), . 1990. Seabrook Environmental the variability was unrelated to Seabrook Studies. 1989 Data Report. Technical Station operation. Report XXI-I.
. 1991a. Seabrook Environ-mental Studies. 1990 Data Report.
7.5 LITERATURE CITED Technical Report XXII-I. Bousfield, E.L. 1973. Shallow-Water . 1991b. Seabrook Environ-Gammaridean Amphipoda of New England, mental Studies, 1990. A character-Comstock Publishing, Ithaca, NY. 312 ization of environmental conditions in pp. the Hampton-Seabrook area during the operation of Seabrook Station. Techni-Clark, K.B. 1975. Nudibranch life cycles cal Report XXII-II. In the northwest Atlantic and their relationship to the ecology of fouling . 1992. Seabrook Environmental communities. Helgo. Wiss. Meere. Studies, 1991. A characterization of sunters. 27-28-69. environmental conditions in the Hampton-Seabrook area during operation of Field, B. 1982. Structural analysis of Seabrook S tat ion. Technical Report fouling community development in the XXIII-I. Damariscotta River estuary, Maine. J. Exp. Biol. Ecol. 57:25-33. . 1993. Seabrook Environmental Studies. Unpublished 1992 data. Mueller-Dombols, D. and H. E11enberg. 1974. Aims and Methods of Vegetation Padmanabhan, M. , and G.E. Hecker. 1991. Ecology. John Wiley & Sons, NY. 547 Comparative evaluation of hydraulic pp, model and field thermal plume data. Seabrook Nuclear Power Station. Alden Nair, K.K.C. and K. Anger. 1980. Sea. Research Laboratory, Inc. 12 p. sonal variation in population structure and biochemical composition of Jassa Rastetter, E.B. and W.J. Cooke. 1979. falcata off the Island of Helgoland Response of marine fouling communities (North Sea). Est. Cost. Mar. Sci. to sewage abatement in Kaneohe Bay, 11:505-513. Oahu, Hawaii. Mar. Biol. 53:271-280. Normandeau Associates, Inc. 1986. SAS Institute, Inc. 1985. User's Guide: Seabrook Environmental Studies. 1985 Statistics, Version 5 Edition. SAS data report. Technical Report XVII-I . Institute Inc. Cary, NC 956 pp.
. 1988a. Seabrook Environ. Sokal, R.R., and F.J. Rohlf. 1969.
mental Studies. 1987 data report. Biometry. W.H. Freeman and Co., San Technical Report XIX-VI, Francisco. xxi + 776 pp.
. 19 M h . Seabrook Environ- Teyssandier, R.G. , W.W. Durgin, and G.E.
mental Studios. 1987. A character- Hecker. 1974. Hydrothermal studies of diffuser discharge in the coastal 7-19
1 SURFACE PANELS environment: Seabrook Station. Alden Research Laboratory Report No. 86-24. 1 l 1 7-20
TABLE OF CONTENTS PAGE 8.0 EPIBENTHIC CRUSTACEA . . . . . . . . . . . . . . . . . . . . . 8-1 8.1 OBJECTIVES . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1 8.2 METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1 8.2.1 Field . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1 8.2.2 Laboratory . . . . . . . . . . . . . . . . . . . . . .. . 8-3 8.2.3 Analytical Methods , , . . . . . . . . . . . . . . . 8-3 8.3 RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3 8.3.1 American Lobster (#omarus americanus) . . . . . . . . . . . 8-3 8.3.2 Jonah Crab and Rock Crab . . . . . . . . . . . . . . . . . 8-10 8.4 DISCUSSION . . . . . . . . . . . . . . . . . . . . . . 8-11 8.4.1 American Lobster . . . . . . . . . . . . . . . . . . . . . 8-11 l 8.4.2 Jonah and Rock Crabs . . . . . . . . . . . . . . . . . . 8-15 l
'1 l
8.5 LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . 8-15 l l l 8-i ; _. _ . ~
LIST OF FIGURES PACE 8-1. Epibenthic crustacea (American Lobster, Jonah and Rock Crabs) sampling stations . . .. . . . . . . . . . . . . . . . . . . . . 8-1 8-2. Prooperational mean and 95% confidence limits and 1992 and 2 operational mean of a. weekly density (no./1000m ) of lobster larvae at Station P2, b. lobster larvas density by lifestage at P2, c. Monthly CPUE (15 traps) of adult lobster at Station L1, and d. monthly CPUE (15 traps) of legal-sized lobster at Station L1 . .... .. . . . . . . . . . . . . , . . . . . . 8-7 8-3. a. Percentage and b. catch (per 15 trap effort) of legal-sized and sublegal-sized lobster and c. sira-class distribution at the nearfield site L1 from 1975-1992 . . . . . . . . . . . . . . 8-9 8-4. Monthly means and 95% confidence intervals of log (x+1) density (no./1000 m3 ) of Concer spp. larvae at Station P2, and catch per unit effort (15 traps) of Jonah and Rock Crabs at Station L1 during the preoperational period (1978-1989: larvae,. 1975-1989: adults) and monthly means during the operational period (1991-1992) and 1992 . . . . . . . . . . , . . . , , , . . . 8-12 LIST OF TABLES 8-1. GEOMETRIC NEAN ABUNDANCE (LARVAE: LOBSTER = NO./1000 m2 ; CANCER SPP. = NO./1000 m') OR KEAN CATCH PER UNIT EFFCRT (NO./15 TRAPS) . AND 95% CONFIDENCE LIMITS OF EPIBEtGHIC CRUSTACEA AT NEARFIELD (P2, P5 FOR LARVAE, L1 FOR ADULTS) AND FARFIELD (P7,.L7) STATIONS DURING PREOPERATIONAL YEARS, AND MEAN ABUNDANCE OR CATCH FOR 1992 AND THE OPERATIONAL PERIOD ... . . . . . . . . . . . . . . . . . . . . . 8-4 1 8-2. RESULTS OF ANALYSIS OF VARIANCE COMPARING DENSITIES OF j LOBSTER AND CANCER SPP. LARVAE COLLECTED AT INTAKE, l NEARFIELD, AND FARFIELD STATIONS, AND CATCHES OF TOTAL AND LEGAL-SI2ED LOBSTERS, JONAH CRAB, AND ROCK CRAB AT
'8-5 THE NEARFIELD AND FARTIELD STATIONS . . . . . . . . . . . . . . . .
8-3.
SUMMARY
OF POTENTIAL PLANT EFFECTS ON ABUNDANCE OF EPIBENTHIC CRUSTACEA ... . . . . . . . . . . . . . . . . . . 8-13 1 I 8-11 1 b
l-EPIBENTHIC CRUSTACEA 8.0 EPIBENTHIC CRUSTACEA 8.2 HETHODS 8.1 03JECTIVES 8.2.1 Field The objectives of monitoring epibenthic Lobster Larvae (Neuston) cruptacea are to determine the seasonal, ; spatial, and annual trends in larval To monitor distribution of Fomarus density and catch per unit effort (CPUE) americanus larvae, neuston samples were ; for the juvenile and adult stages of collected weekly from May through October American lobster, and Jonah and Rock along horseshoe-shaped tows approximately
~ Crabs. Analyses are done to determine if 1/2 mile (800 m) long on a side. These the discharge from Seabrook Station had tows were centered on the intake (P2),
any measurable effect on the epibenthic discharge (PS), and farfield (P7) stations l crustaceans. (Figure 8-1) . Collections began in 1978 ! N *!E M' ? l Yllak aun
.ku/ \'
0 $ t Neuse ute PAMMELD
. i i. ?
SCAlt ,,;
- N Yrals""
C#M TSOAA, LEGEND gu i 3'i ., . Lobster Larvae Stations
@ , . :::::::::::s p . Macrozooptankton Stations
,, ,, , L = Lobster Traos RfYER ; intake N U*A*b of/TER [,,, ,
A
'UOf% S.L A ROC 1 L1h N '%*C"
%-( >
SAUSBURY BRACH , f Figure 8-1. Epibenthic crustacca (American Lobster, Jonah and Rock Crabs) sampling stations. Seabrook Operational Report,1992. 8-1
- - - - _ _ - - - - - . .. ~ _ . . - .-
EPIDENTIIIC CRUSTACEA at Station P2 and in 1982 at Station P7. clogged due to plankton blooms, tows were At Station PS, collections were made from shortened to 6 minutes. The volume 1988 to the present. Collections were filtered was determined with a General made with a 1-mm mesh net (1 m deep x 2 Oceanics@ digital flowmeter. Upon re-m wide x 4.5 m long) fitted with a General trieval, each not was thoroughly washed Oceanics@ flowmeter and a 40-lb depressor. down with filtered seawater and the
- - Thirty minute surf ace tows were taken with contents preserved in 5-10% borax-buffered the bottom of the net mouth approximately formalin.
0.5 m below the surf ace. The area sampled averaged about 3732 m2 (generally ranging f rom 2874 to 4300 m2) . Juveniles.and Adults (Lobster Trans) In the field, samples were rinsed American lobster (//omarus americanus), through a 1-mm mesh sieve, and sorted in Jonah Crab (Concer borealls) and Rock Crab total under a dissecting microscope. The (Cancer Irroratus) were collected at the live lobster larvae (Stages I-IV) were nearfield discharge Station (L1) and a enumerated and released into llampton farfield station located of f Rye Ledge llarbor . Those samples that were not pro- (L7) (Figure 8-1). Collections began at cessed the day of collection were pre- Station L1 in 1978 and at Station L7 in served in 6% formalin (NAI 1991). 1982. Fif teen 25.4 mm (1 in) mesh experi-mental lobster traps were fished approxi-mately three times per week from June to Cancer apo. Larvae (Macrozoonlankton1 November. Lobster carapace lengths were recorded in the field in the following Cancer spp. larvae as well as other 12.7 mm (1/2 in) size classes: macrozooplankton were sampled twice per month from January through December. On each date, four replicate (paired-se- Lize Class Range quential) oblique tows were made at night mm inches with 1-m diameter, 0.505-mm mesh nets at the intake (P2), discharge (PS), and <54 <2-1/8 farfield (P7) stations (Figure 8-1). 54-67 2-1/8 to 2-5/8 Collections began in 1978 at Station P2 68-79 >2-5/8 to 3-1/8 and in 1982 at Station P7. Collections 80-92 >3-1/8 to 3-5/8 at Station PS occurred from 1982-1984, 93-105 >3-5/8 to 4-1/8 July-December 1986, and from 1978 to the >105 >4-1/8 present. No collections were made in 1985. The nets with depressors were set off the Lobsters in the 80-92 mm (3-1/2 in) class stern and towed for 10 minutes while were recorded in two groups separating the varying the boat speed, causing the net legal and sublegal lobsters. Lobsters to sink to approximately 2 m off the measuring greater than 83 mm (3-1/4 in) bottom and to rise to the surface at least were classified as legal according to 1990 twice during the tow. When nets became State of New flampshire regulations. The 8-2
EPIBENTilIC CRUSTACEA a total number of males, females, and egg- variable station (larvae only), the least bearing females were also recorded, squares means procedure (SAS 1985) was used to determine which variables were significantly different at alpha 5 0.05). 8.2.2 LabEAtan In the laboratory, each macrozooplankton 8.3 EEEE'Is sample was split with a Folsom plankton splitter into fractions that provided 8.3.1 Ame ric an __ Lobs te r (Famarm counts of at least 30 individuals of oarericanus) Caacer spp. larvae. A maximum of 100 milliliters of settled plankton, generally Lobster Larvan 1/4 of the original sample volume was ana- , lyzed. Cancer spp. larvae were identified Lobster larvae densities during 1992 to developmental stage and enumerated (NAI were higher than preoperational (1988-1991). 1989) densities at all three stations (Tables 8-1, 8-2)., During the two-year In the laboratory, adult Cancer spp. operational period, the average larval were enumerated, sexed, measured to the densities were significantly higher than nearest millimeter, and, in addition, the the average preoperational densities at number of egg-bearing females was record- all stations. Significant differences ed, were also found among weeks. There were no differences among the three stations during the 1988-1992 study period. High 8.2.3 lLnalvtical Heihada densities- of lobster larvae in 1992 occurred at the nearfiald station in July An analysis of variance (SAS 1985) was and August, with densities low in May, used on log (x +1) transformed density of June and October, similar to previous larvae to determine dif ferences between years (Figure 8-2a). The occurrence of the average abundances for the operational peak abundances of lobster larvae in the (1991-1992) and recent preoperational study area is consistent with other _(1988-1989, when all three stations were studies in New England, summarized by sampled concurrently) periods at nearfield Fogarty and Lawton (1983) as occurring and f arfield stations. Weekly means were from June through August. Other studies analyzed for lobster larvae and biweekly relate first appearance with a surface (twice a month) means were used for Cancer temperature of 12.5'C (Harding et al. spp. Untransformed monthly mean abundanc- 1983), which typically occurs in June or es (catch per unit effort) were used for July in the study area (Section 2.0). juvenile and adult lobster and crabs for the preoperational (1982-1989) and oper- Increased density in 1992 was due mainly ational (1991-1992) periods. Wher the F to increases in Stage IV larvae, histori- > value was significant for the interaction cally the most numerous of the four term (Proop-Op X Station), or class lifestages (Figure 8-2b). Stage I larvae 8-3
TABLE 8-1. 2 3 GEOMETRIC MEAN ABUNDANCE (LARVAE: LOBSTER = NO./1000 m - CANCER SPP. = NO./1000 m ) OR MEAN CATCH PER UNIT EFFORT CRUSTACEA AT NEARFIELD (P2, PS(NO./15 TRAPS) FOR LARVAE, ANDADULTS) L1 FOR 95% CONFIDENCE LIMITS AND FARFIELD (P7,OFL7)EPIBEhTHIC STATIONS DURING PREOPERATIONAL YEARS, AND MEAN ABUNDANCE OR CATCH FOR 1992 AND THE OPERATIONAL PERIOD. SEABROOK OPERATIONAL REPORT, 1992. PREOPERATIONAL YEARS
- SPECIES STATION LCL MEAN UCL 1992 OPERATIONALb (period sampled)
- MEAN MEAN Lobster larvae P2 0.4 0.4 0.5 1.4 1.2 (May-Oct) P5 0.0 0.4 3.2 1.1 1.0 P7 0.4 0.7 0.8 1.6 1.4 Lobster, total L1 67.2 70.6 74.1 57.7 62.8 (Jun-Nov) L7 82.2 66.9 91.6 55.5 59.1 Lobster, legal-sized L1 4.9 5.9 7.5 2.3 2.2
, (Jun-Nov) L7 5.6 6.0 6.4 2.6 2.1 b Lobster, female L1 37.1 39.0 40.9 28.7 35.8 (Jun-Nov) L7 44.6 47.1 49.6 27.4 32.3 Lobster, ovigerous L1 0.5 0.6 0.6 0.5 0.5 (Jun-Nov) L7 0.4 0.6 0.7 0.7 0.7 Cancer spp. larvae P2 7642.8 10917.6 15595.4 18919.5 26941.3 (May-Sep) P5 3425.4 5512.1 8869.6 16476.7 17209.9 P7 5103.8 8759.9 15034.5 25086.5 25843.0 Jonab crab, total L1 11.3 12.6 13.8 16.6 13.6 (Jun-Nov) L7 8.7 9.5 10.3 10.2 8.1 Jonab crab, female L1 8.7 9.7 10.7 11.2 9.5 (Jun-Nov) L7 6.1 6.8 7.4 7.2 5.3 ,
Rock crab, total L1 2.1 2.5 2.9 7.0 4.6 (Jun-Nov) L7 1.2 1.6 1.9 3.4 4.2 Rock crab, female L1 0.3 0.5 0.7 2.0 1.3 ! (J un-Nov) L7 0.2 0,3 0.4 0.3 1.3 "Preoperational-larvae: 1988-89, all other lobster and crabs: 1982-89, mean of annual means.
%perational: 1991-1992, mean of annual means.
- Sampled year-round but abundance computed for peak period (May - September).
TABLE 8-2. RESULTS OF ANALYSIS OF VARIANCE COMPARING DENSITIES OF LOBSTER AND CANCER SPP. LARVAE COLLECTED AT INTAKE, NEARFIELD, AND FARFIELD STATIONS, AND CATCHES OF TOTAL AND LEGAL-SIZED LOBSTERS, JONAH CRAB, AND ROCK CRAB AT THE NEARFIELD AND FARFIELD STATIONS. SEABROOK OPERATIONAL REPORT, 1992. SOURCE OF SPECIES VARIATION
- df SS Fb HULTIPLE COMPARISDNSC (ranked in decreasing order)
Lobster larvae Preop-Op 1 2.40 58.71 *** Op> Preop (May-Oct) Station 2 0.02 0.19 NS Year (Preop-Op) 2 0.22 265.00 NS Week (Year) 76 25.62 8.24 *** Preop-Op X Station 2 0.07 0.89 NS Error 177 Lobster Preop-Op 1 34,252.15 37.76 ** T (total catch) Station 1 6,394.86 7.05 ** L7 Pre L1 Pre L1 Op L7 Op
- 8 i i (Jun-Nov) Year (Preop-Op) 152,446.60 21.01 ***
i Month (Year) 49 1,388,662.76 31.24 *** i Preop-Op X Station 1 15,916.90 17.55 *** Error 1183 1,073,021.80 Lobster Preop-Op 1 2,100.51 187.21 *** Op< Preop (legal size) Station 1 0.02 0.00 NS (Jun-Nov) Year (Preop-Op) 8 3,658.03 40.75 *** Month (Year) 49 7,053.58 12.83 *** Preop-Op X Station 1 0.45 0.04 NS Error 1183 13,273.14 Cancer spp. Preop-Op 1 6.01 7.82 ** Op> Preop larvae Station 2 1.62 1.05 NS (May-Sep) Year (Preop-Op) 3 0.85 0.37 NS Sample Period 20 109.92 7.15 *** Preop-Op X Station 2 0.59 0.38 NS Error 121 93.04 (continued)-
T TABLE 8-2. (Continued) SOURCE OF SPECIES . VARIATION
- df SS Fb MULTIPLE COMPARISONS *
(ranked in decreas.ing order) Jonah crab Preop-Op 1 4.48 0.05 NS (Jun-Nov) Station 1 2,970.69 34.74 *** LI>L7 Year (Preop-Op) 8 165,139.66 24.18 *** Month (Year) 49 63,937.86 15.26 *** Preop-Op X Station 1 236.38 2.76 NS Error 1161 99,283.77 Rock crab Preop-Op 1 455.49 22.79 *** Op> Preop (Jun-Nov) Station 1 70.93 3.55 NS oo Year (Preop-Op) 8 3,333.19 20.85 *** 4, Month (Year) 49 5,808.22 56.93 *** Preop-Op X Station 1 12.29 0.61 NS Error 1161 23,205.84
" Preop-Op = Preoperational period (Lobster and Cancer larvae, all stations: 1988, 1989; Adult lobster and crabs: 1982-1989); Operational periods 1991 and 1992 regardless of Station or month.
Station = Station differences (Lobster and Cancer Larvae: P2, P5, P7; Adult lobster: Discharge (L1) and Rye Ledge (L7)) regardless of year, month or period. Preop-Op X Station = Interaction of main effects. Year' (Preop-Op) = Year nested within preoperational and operational periods regardless of year, month or Station. Month (Year) or Week (Year) = Month or week nested within Year, regardless of Station.
%IS = Not significant (p>0.05)
* = Significant (0.052p>0.01)
** = Highly significant (0.012p>0.001)
*** = Very Highly Significant (0.0012p)
Underlining signifies no significant differences (a 5 0.05) among least squares means with a paired r-test.
Lobster Larvae:- ]
- b. Preoper:tionaland Operational
- c. Season *I Trzads Trends by Stage 1.6 - Preoperational(1978-1989) 0.33 - e bap no t (19781989) .
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- c. Total Catch d. Legal. Sized 100 - Proopersuonal (19821989) 12 - Preoperuuonal (19821989)
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a \ 20 , , , , , , 0 , , , , , , EN At AUG SEP OCT NOV LN At AUG SEP . OCr NOV i MONT!{ MONTl! 1 1 Figtn: 8 2. Preoperational mean and 95% confidence limits and 1992 and operational mean of a. weekly 1 density (no/1000m9 of lobster larvae at Station P2, b. lobster larvae density by lifestage at .. ; P2, c. monthly CPUE (15 traps) of adult lobster at Station L1, and d. monthly CPUE (15 traps) H of legal. sized lobster. Seabrook Operational Report,1992. 8-7
I EPIDENTl!IC CRUSTACEA
=-
were the second-most abundant, both in lobster catch are due in part to regional 1992 and during the preoperational period. temperature changes, which act to increase i Stage II and Stage III larvae have the activity level of adults, in turn historically been the least abundant life- enhancing the likelihood of being caught stages. Stage I lobster predominated in (McLeese and Wilder 1958, Dow 1969). In the majority of other studies, mainly from addition, temperature may nf feet seasonal southern New England, as reviewed by lobster migrations (Campbell 1986). In Fogarty and Lawton (1983). Stage IV New Hampshire, adult lobsters are thought lobsters, however, were most numerous in to move inshore in spring and summer and some years in Cape Cod and Buzzards Bay, of fshore in fall and winter (N11FG 1992). and Long Island Sound. A preponderance ! of Stage IV larvae typified the coast of southwestern Nova Scotia south to New Lezal-sized Lobster Hampshire, supplied by lobster stock in the warm southwestern waters of the Gulf Catches of legal-sized lobsters are of Maine and Georges Bank (Harding et al. affected by the same environmental con-1983, Harding and Trites 1988). ditions that affect total catch as well as changes in the regulations governing the fishery. The legal-size limit for Total Catch: Jnveniles and_Mults lobsters was increased in 1984,1989, and in 1990, and is currently defined as a The 1992 catch per unit ef fcrt (unit carapace length of 83 mm (3-1/4 in). Each effort = 15 traps) for total lobster was increase in the legal size reduced the lower than 1991 and 1990 catches at both proportional catch of legal sized lobsters the nearfield (L1) and farfield (L7) (Figure 8-3). During 1992, the average stations (Table 8-1; NAI 1991). Although catch of legal-sized lobsters was less both stations showed a decline in the than the 95% confidence limit of the catch between the preoperational and preoperational average. During the two-operational periods (Table 8-1), it was year operational period, the average only significant at the farfield station annual catch of 2.2 lobsters per 15-trap (Table 8-2). effort at the nearfield station was. significantly lower than the preopera-The seasonal pattern during the overall tional average of 5.9 (Tables 8-1,2). A operational period (1991-1992) was similar similar decline was observed between the to the preoperational period, with the preoperational and operational periods at peak catches in September. In 1992, the farfield station. There was no however, the total catch peaked in August. significant difference between the Significant dif ferences were noted among nearfield and farfield stations. months (Table 8-2) . Total adult catch at , The seasonal pattern of legal-sized the nearfield station during the opera-tional period was higher than the average lobster catches in 1992 showed an August preoperational catch in July and August peak and a graduni decline in September (Figure 8-2c). Seasonal variations in and October, similar to seasonal patterns 8-8 i e
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Yp$ q\o8 geS ** ** /, 4 Figure 8-3. a. Percentage a.,d b. catch (per 15 trap effon) of legal-sized and sublegal sized lobster and c size-class distribution at the nearfield site L1 from 19751992. I Seabrook Operational Report,1992. a 8-9
EPIDENTHIC CRUSTACEA observed during the preoperational period CPUE, composing 0.9% of the total catch (Figure 8-2d). S'ignificant differences at the nearfield station. Catches of were noted among months (Table 8-2). ovigerous females at Rye Ledge were slightly higher, averaging 0.7 per effort or 1.3% of the total catch,(Table 8-1). ; Size Class and Sox Distribution The percent of agg-bearing female lobsters has been variable, but averaged less than The majority of lobsters collected at 1% during the preoperational period (Table the nearfield station in 1992 were in the 8-1). Changes in legal-size limits for 68-79 mm (2-5/8"-3-1/8") size class, as fishing do not appear to have affected the was true in previous years beginning in proportion of egg-bear.tng females. NHFG 1980. Lobsters measuring 54-67 mm (2- studies (Grout et al. 1989) found that 1/8"-2-5/ *") ranked second in abundance 0.4% of the total lobsters examined during in 1992 aad as in previous years (Figure lobster surveys of New Hampshire coastal 8-3). Catches during 1992 in the 80-92 waters from 1983-1985 were berried. mm size class, which includes both legal-sized and sublegal-sized lobsters, were In 1992, 6 lobst.ers measuring <50 mm - the lowest since 1983. The decline may were impinged in the plant's cooling water be due to lower water temperatures in 1992 system. Four lobsters were impinged in (Section 2.0), which decrease catchability 1990, and 29 were impinged in 1991 (NAI (McLeese and Wilder 1956, Dow 1969). A 1992). Sixty-six percent of those impinged similar decline was noted by other inves- in 1991 were found in November following , tiget. ors ( Addison and Fogarty 1993). In a severe northeastern storm. This level a 1991 study of New Hampshire coastal of impingement does not represent a threat areas, the majority of lobsters measured to the local lobster population. between 77 and 80 mm, with an average length of 78 mm (NHFG 1972). 8.3.2 Jonah Crab and Rock Crab Female lobster catch averaged 28. 7 CPUE at the nearfield station in 1992, 50% of Larvae ) the total lobster population (Table 8-1). ) During the preoperational period the Concer spp. (Cancer borea11s and proportion of females averaged 55%. The Cancer 1rroracus) larvae had higher peak ( proportion was similar at Rye Ledge, both abundances in 1992 in comparison to the .) in 1992 (49%) and during the preopera- preoperational period at all three sta- _! tional period (54%). NHFG studies found tions (Table 8-1). During the two year that females constituted 52% of the total operational period, the average density legal-sized population in the New Hamp- was significantly higher than the pre-shire coastal arsa (Grout et al. 1989), operational average at each station (Table 8-2). The seasonal trend of occurrence Egg-bearing female lobsters represented at nearfield Station P2 in 1992 and for a small component of the lobster popula- the average operational period was similar tion for 1992; berried females average 0.5 to previous years. Densities were low j i 8-10 , l 1
i EPIBENTHIC CRUSTACEA l from January through April, peaked from (Figure 8-4). During the preoperational
'May or June through September, then period, abundance peaked in August. Rock decreased from October through December Crab catches were less abundant than Jonah (Figure 8-4) . Seasonal differences were Crab in the study area (Table 8-1),
substantiated by a significant dif ference probably a result of this species' ] among sampling periods (Table 8-2). preference for sandy habitat rather than , the cobble-rock that predominates in the i area (Jef feries 1966, Bigford 1979). Rock ] Total Catch: Juveniles and Adults Crab catches as well as intra-specific competition (Richards et al.1983) during i In 1992, catch per unit ef fort for Jonah the operational period averaged 4.6 CPUE j ~ Crab (Cancer borealis) at nearfield at the nearfield site and 4.2 at the (16.6) and forfield (10.2) stations was farfield. Differences between stations higher than the preoperational average were not significant (Tables 8-1, 8-2). (12. 6 and 9.5, respectively) (Table 8-1) . Rock Crab catches were significantly Highest catches in 1992 at the nearfield higher during the operational period at ! station occurred from July through Sep- each station, representing an area-wide tember, lacking.the typical August peak increase. Female crabs composed approxi-evident in the preoperational average mately 20% of the total catch during the (Figure 8-4) . Annual Jenah Crab catches preoperational period. The proportion l during the operational period (1991-92) increased to 28-30% at each station during i have averaged 13.6 CPUE at the nearfield the operational period (Table 8-1). l i t station and 8.1 at Rye Ledge, and were not significantly different than the preopera- ; tional average at both stations (Tables 8.4 DISCUSSION ; 8-1, 8-2). Catches at Rye Ledge wero ) lower than those at the nearfield station 8.4.1 American Lobster during the opecational period, consistent I with previous years. Femal'e crab catches Eggs and newly-hatched larvae require j in 1992 comprised 67% and 71% of the total a sea water temperature above 10'C (50'F) I catch at the discharge and farfield in order to survive. Larvas spend roughly stations, respectively. During the pre- one month in the water column, molting q operational period the proportion averaged three times before they settle to the l 77% and 72% at the near- and farfield bottom. It has been suggested that 1 stations, respectively (Table 8-1). frequency of molting and growth rate l increase as temperature increases (Mariano In 1992 the total Rock Crab (Cancer 1993). frroratus) CPUE at the nearfield .(16.6) i and farfield (10.2) was higher than the Lobster larvae have traditionally been preoperational average (12.6 and 9.5, thought of as strictly neustonic, although respectively)(Table 8-1). In 1992, catch- current research suggests that they are es at the nearfield site were highest in distributed throughout waters above the
. June and July, but decreased in August thernmocline (Harding et al. 1987,
~1 8-11 l l
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.......... % ,mi
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- o. --o-- 1992 t2 -
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..................., ~, i V
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.- 7 -
'....2N~. l l
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2- - 3 A -,_n__ ' 0 i i i i e i RN Ra, AUG SIP OCr NOV MONTH 3 Figure 8-4 Monthly means and 95% confidence intervals oflog (x+1) density (no./1000 m ) of Cancer spp. larvae at Station P2. and catch per unit effort (15 traps) of Jonah and Rock Crabs at Station L1 during the preoperational period (19781989: larvae, 1975-1989: adults) and monthly means during the operational period (1991 1992) and 1992. Seabmok Operational Report.1992. 8-12
.~ . . . .. -, . - .- . - - . - - - . .
EPIDENTHIC CRUSTACEA Boudreau 1991). Lobster larvae could be benthic phase than by larval abundance enposed to discharge plume, ultimately (Wahle and Steneck 1991). Lobster larvae af fecting survival, molting and successful have historically been relatively rare in bottom settlement of Stage IV lobster. the study area, averaging less than-1 per Juvenile lobsters in the study area are 1000 m 8
. Densities during the operational
- recruited from Stage IV larvae (the stage period were significantly higher than prior to benthic settlement) originating observed historically at all three from the Gulf of Maine and Georges Bank stations (Table 8-3). Thus increased (Harding et al.1983). Although the level densities appear to'be part of an area .
of juvenile recruitment has been correlat- wide trend rather than an effect of plant ed with abundances of larvae (Harding et operation. These density increases appear al' 1982, Harding et al. 1983), others
, to be unrelated to the increase in the have f ailed to confirm this relationship legal size limits (and.related decrease (Fogarty and Idoine 1986). Recent re- in legal-sized CPUE) because Stage IV lar-search indicates that successful benthic vae, the predominant lifestage collected, recruitment of larval lobsters is affected do not originate in the study area more by habitat ava!1 ability for the early (Harding et al. 1983).
1 TABLE 8-3.
SUMMARY
OF POTENTIAL PLANT EFFECTS ON ABUNDANCE OF EPIBENTHIC EPIBENTHIC CRUSTACEA. SEABROOK OPERATIONAL REPORT, 1992. OPERATIONAL PEhIOD DIFFERENCES BETWEEN SIMILAR TO PREOPERATIONAL AND OPERATIONAL PARAMETER HEASURED PREOPERATIONAL PERIOD
- PERIODS CONSISTENT AHONG STATIONS *~
Lobster: Op> Preop Yes Larvae Lobster: No NF: Op= Preop Toral Catch FF: Op< Preop Lobster: Op< Preop Yes Legal-Sized Catch Cancer spp.: Op> Preop Yes Larvae Jonah Crab: Yes Yes Total Catch i l Rock Crab: Op> Preop Yes Total Catch based on ANOVA results 8-13 J
I' EPIDENTHIC CRUSTACEA Benthic-oriented juvenile and adult Campbell et al. 1991). Preliminary lobsters would most likely be susceptible results from other studies have documented to the potential ef fects of plant opera- a similar decrease in catch coinciding tion by changes in their food sources with decreased water temperature in 1992 resulting from the effects of increased (Addison and Fogarty 1993). detritus around the discharge diffuser. Temperature in general can af fect lobster In Maine, newly recruited legal-sized activity - levels and the likelihood of lobsters are almost completely harvested capture (Dow 1969) as well as migratory in the same year (Fogarty 1988). His-behavior (Campbell 1986). Changes in torically, in this study, percentages of bottom temperature resulting from Seabrook legal-sized lobsters have decreased with Station are unlikely to occur because of each increase in the legal-size limit, as t the design of the discharge diffuser and would be expected. Approximately 2.2 j the buoyancy of the discharge plume. legal-sized lobsters (per 15 trap effort) Seasonal patterns of total lobster catches were caught at the nearfield site in the in the 1991-92 operational period were operational period, similar to levels in similar to previous years. The total 1990, when the last legal-size increase ! catch of lobster was lower at both was enacted in New Hampshire. The trend stations during the operational period (as of decreasing catches of legal-sized j compared to the preoperational period), lobsters is similar between the nearfield However, the decrease was only significant and farfield stations, indicating that it at the farfield station (Table 8-3), may be a result of changes in legal-size 4 definition rather than an effect of plant The total lobster catches are influenced operation. Proportions of female and egg-by a number of f actors. Inshore lobster bearing lobsters captured were consistent catches have steadily increased in the with previous years. l Gulf of Maine and middle Atlantic from . 1978-1991 (NOAA 1992). The broadscale Impingement of lobsters in the cooling ) increase may be in large part due to the water system was not expected because of increase in fishing effort (especially the the off-bottom intake location. However, number of pots fished) and in part due to in 1991, 29 sublegal-sized lobsters were an increase in abundance of lobsters (NOAA impinged, most after a severo northeastern 1992). Lobster catches in this program storm in October, which probably entrained have utilized a standard fishing effort juveniles into the water column, increas-and thus are a better estimate of the ing their susceptibility. Only ' four c catchable population than landing statis- lobsters were impinged in 1990, and six ) i tics. . The population increase through ' in 1992. This level of impingement does l 1991 and subsequent decrease in 1992 may not pose a threat to the local lobster be the result of water temperature populatfor. fluctuations throughout the region, which have been correlated with lobster land-ings, both in the current year and after a six-year lag period - (Fogarty 1988; 8-14 .; c
'l EPIBENTHIC CRUSTACEA 1
8.4.2 Jonah and Rock Craba Campbell, A. , 0.J. Noakes and R.W. Elmer, .i 1991, Temperature and Lobster, Eomarus -l Jonah and Rock Crabs are important americanus, yield relationships. Can. invertebrate predators in the study area J. Fish. Aquat. Sci. 48:2073-2082. and could be subject to the same potential ,l for impact as lobsters. The Jonah Crab catch in the operational period was Dow, R. 1969. Cyclic and geographic ; similar to the catch during the preoper- trends in seawater temperature and abun-ational period at both near- and farfield dance of American lobster. Science stations (Table 8-3). 164:1060-1063. Rock Crab are less prevalent than their Fogarty, M.J. 1988. Time series models congener in the study area, probably of the Maine lobster fishery: the because of their preference for sandy effect of temperature. Can. J. Fish, substrate (Jefferies 1966). Annual Aquat. Sci. 45:1145-1153. catches of rock crab were significantly higher during the operational period than Fogarty, M.J., and J.S. Idoine. 1986. during the preoperational period at both Recruitment dynamics in an American near- and farfield stations. lobster (Romarus americanus) population. Can. J. Fish. Aquat. Sci. 43:2368-2376. 8.5 LITERATURE CITED Fogarty, M.J., and R. Lawton. 1983. An overview of larval American lobster Addison, J. and M. Fogarty. 1993. Eomarus americanus, sampling programs Juvenile lobster habitat limitation: in New England during 1974-70. pp 9-14, what can landings tell os. The Lobster In. M.J. Fogarty (ed. ) Distribution and Bulletin. 6(2):2. Relative Abundance of American Lobster, , Somarus americanus, Larvae: New England Boudreau, B. Y. Simard and E. Bourget. Investigations During 1974-79, NOAA 1991. Behavioral responses of the Tech. Rept. NMFS SSRF-775. planktonic stages of the American lob-ster Eomarus americanus to the thermal Grout, D.E. , D.C. McInnes and S.G. Perry. '~ gradients, and ecological implications. 1989. Impact evaluation of the increase Mar. Ecol. Prog. Ser 76:13-23. in minimum carapace length on the.New Hampshire lobster fishery. New Hamp-Campbell, A. 1986. Migratory movements shire Finh and Game Department. of ovigerous lobsters, Nomarus americanus, tagged of f Grand Manan, Harding, G.C. , K.F. Drinkwater, and W.P. eastern Canada, Can. J. Fish. Aquat. Vass. 1983. Factors influencing the 1 Sci. 43:2197-2205. size of American lobster (#omarus americanus) stocks along the Atlantic coast of Nova Scotia, Gulf of S t '. Lawrence, and Gulf of Maine: a new 8-15 l i
l l l l EPIDENTilIC CRUSTACEA l l synthesis. Can. J. Fish. Aquat, Sci. New England Fishery Management Council. 40:168-184. ' 1983. Final environmental impact ! statement and regulatory impact review j liarding, G.C., J.D. Pringle, W.P. Vass, for the American Lobster Fishery Man-S. Pearre, and S. Smith. 1987. Ver- agement Plan. March 1983, tical distribution and daily movements of larval lobsters #omarus americanus NOAA. 1992. Status of the fishery , I over Browns Bank, Nova Scotia. Mar. resources of the northeastern United Ecol. Prog. Ser. 41:29-41. States for 1992. NOAA Tech. Memo. NMFS-F/NEC-95, 133 p. liarding, G.C., and R.W. Trites. 1988. Dispersal of Eomarus americanus larvae Normandeau Associates Inc. 1991. Sea-in the Gulf of Maine from Brown's Bank. brook Environmental Studies. 1990 Data Can. J. Fish. Aquat. Sci. 45:416-425. Report. Technical Report XXII-I. liarding, G.C., W.P. Vass, and K.F. . 1992. Seabrook Environ-Drinkwater. 1982. Aspects of larval mental Studies ,1991. A characteriza-American lobster (Nomarus americanus) tion of environmental conditions in the ecology in St. Georges Bay, Nova Scotia. Hampton-Seabrook area during the Can. J, Fish. Aquat Sci. 39:1117-1129. operation of Seabrook Station. Tech. Rep. XXIII-I. Jefferies, ll.P. 1966. Partitioning of the estuarine environment by two species SAS Institute, Inc. 1985. User's Guide: of Cancor, Ecology 47(3):477-481. Statistics, Version 5 edition. SAS Institute, Inc. Cary, N.C. 956 pp. McLeese, D. , and D.G. Wilder. 1958. The activity and catchability of the lobster Wahle, R.A. and R.S. Steneck. 1991. (#omarus americanus) in relation to Recruitment habitats and nursery ground temperature. J. Fish. Res. Bd. Canada of the American lobster Eomarus 15:1345-1354, americanus: a demographic bottleneck? Mar. Ecol. Prog. Series. 69:231-243. Mariano, M. 1993. American lobster. Nil Fish and Game and NOAA Agreement
#M9270R0188-01. 4p.
New llampshire Fish and Game Department. 1992, Monitoring of the American lob-stor resource and fishery in New Hamp-shire - 1991. Performance report sub-mitted to the National Marine Ficheries Service Management Division under con-tract no. NA16FI-0353-02, 26 p. 8-16
TABLE OF CONTENTS PAGE s 9.0 ESTUARINE STUDIES . . . . . . . . . . . . . . . . . . ... . . . . . . 9-1 9.1 OBJECTIVES . . . . . . . . . . . . . . . . . . ..... . . . . . 9-1 9.2 METHODS . . . . . . . . . . . . . . . . . . . . ... . . . . . 9-1 9.2.1 Field and Laboratory . . . . . . . . . . . ... . . . . . 9-1 9.2.2 Analytical Methods . . . . . . . . . . . ... . .. . . . . 9 9.3 RESULTS . . . . . . . . . . . . . .. ... .. . . . . . 9-2 9.3.1 Physical Environment . . . . . . . . . . . .... . . . . . 9-2
- =
9.3.2 Macrofauna . . . . . . . . . . . . . . . . . . . .. . . 9-7 9.4 DISCUSSION . . . . . . . . . . . . . . . . . ... . . . . 9-13 9.4.1 Physical Environment . . . . . ... . . . . . . . 9-13 9.4.2 Macrofauna . . . . . . . . . . . ... . . . . . 9-13 9.5 LITERATURE CITED . . . . . . . . . . . . .. . ... . . . . 9-15 4 4 4 9-1
~ m. . ._ . _ _ _ - ._ __ ._ m _ _-- _ - . . .__
1
.1 l
4 LIST OF FIGURES PAGE 9-1. Hampton-Seabrook estuary temperature / salinity and benthos sampling stations . . . . . . . . . . . . . . . . . . . . . 9-1 4 9-2. Monthly means and 95% confidence limits for precipitation measured at Seabrook Station from 1980-1992 (excluding 1984-1986) and surface salinity and temperature taken at low tide in Browns River from May 1979-December 1992 and monthly means in 1992 . . . . . . . . . . . . . . . . . . . . 9-3 LIST OF TABLES
~
9-1. MEAN MONTHLY SEAWATER SURFACE SALINITY (ppt) AND TEMPERA-TURE (*C) TAKEN IN BROWNS RIVER AND HAMPTON HARBOR AT HIGH AND LOW TIDE, MAY 1979 - DECEMBER 1992 . . . . . . . . . . . . 9-5 9-2. ANNUAL MEAN WITH 95% CL FOR TEMPERATURE ('C) AND SALINITY (ppt) TAKEN AT BOTH. HIGH AND LOW SLACK TIDE FROM BROWNS RIVER AND HAMPTON HARBOR FROM 1980-1992 . . . . . . . . . . . . . . 9-6 2 9-3. MEAN NUMBER OF TAXA AND THE GEOMETRIC MEAN DENSITY (No./m ) FOR EACH YEAR AND OVER ALL YEARS WITH 95% CONFIDENCE LIMITS FROM ESTUARINE STATIONS AT BROWNS RIVER (3) AND HILL CREEK (9) SAMPLED FROM 1978 THROUGH 1992 9-8 (EXCLUDING.1985) . . . . . . . . . . . . . . . . . . . . . . . . . 9-4. RESULTS OF 0FE-WAY ANALYSIS OF VARIANCE AMONG YEARS FOR THE MEAN NUMBER OF TAXA (per 5/16 m8 ) AND LOG (x+1) 2 TRANSFORMED DENSITY (No./m ) 0F THE MOST ABUNDANT ESTUARINE SPECIES AND THE TOTAL DENSITY OF MACROFAUNA COLLECTED AT ESTUARINE STATIONS FROM 1978 THROUGH 1992 9-10 (EXCLUDING 1985) . . . . . . . . . . . . . . . . . . . . . . . . . 9-5.
SUMMARY
OF EVALUATION OF EFFECTS OF OPERATION OF SEABROOK STATION IN HAMPTON HARBOR ESTUARY . . . . . . . . . . . 9-14 9-11 q ,- - -
ESTUARINE BENT 110S 9.0 ESTUARINE STUDIES 9.2 HETHODS 9.1 QiLIECTIVES 9.2.1 Fleid and Laboratory The objectives of the estuarine benthic Surface temperature ('C) and salinity program are to ldentify spatial and annual (ppt) were measured at Browns River trends of benthic macroinvertebrates in (Station BR) and llampton llarbor (Station llampton-Seabrook estuary. Trends between Hil) once a week during slack water at both 1978 and 1992 were examined to determine high (flood) and low (ebb) tide (Figure l potential effects of the Settling Basin 9-1). Precipitation (rain and melted snow discharge and Seabrook Station operation and ice) was continuously recorded at the on the estuarine benthic community. meteorological tower located at Seabrook Monthly and anntial trends in temperature, Station. ! salinity, and precipitation in the llamp-ton-Seabrook esttery were examined to Estuarine benthic invertebrates were assist in interpret ing biological trends. sampled in Browns River (Station 3), just
%rr$ht N
' "$?vi? ^
c 7 m. swirroiv aEActs h Js en a m
- s. dred staden .
ed i} LEGEND
.,d @ = Benthos
._, s ll? 4 @@ = Temperature
. Z; [y[(( o .s /Sahrdty l %:,. ']
I /k P NAUUCALHidS MitL GtKKK N i,' j SEABROOK BEACir l Figure 9-1. Hampton Seabrook estuary temperature / salinity and benthos sampling l . stations. Seabrook Operational Report,1992. 9-1
- . - . ~ - - - - . - - - - _ . - . - . _ - _ - - -_ . - -
ESTUARINE BENTH05
.i l
l downstream from the settling pond outfall, 9.3 RESULTS l and in Mill Creek (Station 9), a tidal j creek away from the outfall (Figure 9-1). 9.3.1 Physical Environment Since 1978, two stations (one subtidal, , one intertidal) at each location have been introduction sampled during high tido in May, August, and November. Five samples (0.0625 m2 x The outfall from the Seabrook Station 10.2 cm deep) were taken from each station Settling Basin runs into Browns River, and I with a cofferdam and diver-operated usually contains the freshwater discharge airlift fitted with a 0.79-mm mesh bag. from the station's sewage treatment plant All samples were washed over a 1.0-mm as well as stormwater runoff from the . sieve, preserved in 6% buffered formalin, site. During the period of intake and dis-and sorted under dissecting microscopes. charge tunnel construction from November All non-colonial organisms were identified 1979 through November 1983, the outfall to the lowest possible taxon and enumerat- also discharged increased volumes of ed (NAT 1990), saline water (approximately 25 ppt) from tunnel dewatering (NAI 1991). Once tunnel construction was completed in 1983, the 9.2.2 Analytical Methods discharge volume from the Settling Basin returned to preconsttuction volumes of Weekly measurements of surface water freshwater. In 1992, the total annual salinity and temperature were averaged by volume of discharge (75 x 106 gallons) was month, and patterns of monthly and annual lower than the discharge in the preceding means were examined. Annual mean densi- year (110 x 106 gallons). ties (no./m*) of the total number of individuals and of dominant taxa were The mean monthly precipitation from computed by averaging the log (x+1) 1980-1992 at Seabrook Station showed a ;
- transformed seasonal densities. The predictable trend from year to year with number of taxa in each season was computed peak periods in spring (usually April) and ,
by pooling all five replicates; the three in fall (October or November)(Figure 9-2), seasonal values were averaged to calculate In 1992, April rainfall was about half of the annual mean. A one-way ANOVA was used the average. During the rest of 1992, to test for differences among years, precipitation was near average for every Significant differences (a 5 0.05) were month except June, which was just above .j the upper 95% confidence limit. The total a evaluated with the Waller-Duncan k-ratio e test (SAS 1985), precipitation in 1992 was 35.90 inches,. which was below the average of 39.29 inches for the study period. i 9-2
Precipitation 7- ov a M. 7 ----- tw2 g 6_ ,
- s.
5 <- / - l , , A i:< 1, / ,
- s. _-
/'% ,' ,- >N N"-f' , / A' -'-
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~ ,,-
Ns g . g i-0 1 a 1 i i i i i i i a i JAN FEB MAR APR MAY JUN EL AUG SEP OCT Nov DEC MONTH Salinity w_ - o maM. iw2 23 - T T - -T _ 1
- , , , - '[
f ,_ _ . , - .,
.... ~ .
E is - r . . U 10 - i , S-0 i i i i i i i i i i i i IAN FT.B MAR APR MAY JUN E AUG SEP OCT NOV DEC MONTil Temperature 25 om M. '. r's, t' g .---- in2
. m- , ~
W
$ 13 -
s s h 10 - W 6 .- s ! O s- .- 1 H s I I I I i 4 8 I i i l l 4 JAN PTB MAR APR MAY AN E AUG SEP OCT NOV DEC ! 1 MONTil l 1 l l l I l Figure 9-2. Monthly means and 95% confidence limits for precipitation measured at Seabrook Station from 19801992 (excluding 1984-1986) and surface salinity , and temperature taken at low dde in Browns River from May 1979 December 1992 and monthly means in 1992. Seabrook Operational Report,1992. ; 1 9-3 l
ESTUARINE BENT 110S Browns River llamoton Harbor The most extreme water temperature and At the Hampton Harbor station, the salinities occur at low tido, when the average monthly low tide salinity and 95% water is less influenced by the tidal confidence interval during the study influx of sea water. Water conditions in period ranged from 24.7 i 2.2 ppt in April Browns River at low tide are more likely to 29.4 i 0.7 ppt in September (Table 9-to influence the structure of the estu- 1). The salinity in Hampton Harbor was arine benthic communities, and are the always higher and less variable than in focus of this section. Browns River due to the' moderating influence of sea water from the inlet. The average monthly salinity and 95% The low tido average over all nine years confidence interval from 1979-1992 at low and 95% confidence interval was 27.7 i 0.4 tide in Browns River ranged from 17.1 i ppt. The 1992 average was within the 95% 2.8 ppt in April to 24.5 i 1.5 ppt in confidence limits of the overall average l August (Table 9-1, Figure 9-2). In 1992, (Table 9-2). monthly salinities were within the 95% confidence limits of the average in every In llampton Harbor, the overall average month except January and March. The annual monthly temperature and 95% confidence salinity in 1992 (low tido: 21.9 ppt; intervals at low tide ranged from 1.1 i high tido: 29.6 ppt) was near the average 0.5'C in January to 18. 7 i 0.6*C in August l for the study period (21.2 and 29.7, during the study period (Table 9-1). Due respectively) (Table 9-2). to its proximity to the inlet, the i temperature range in Hampton Harbor was In Browns River, the overall mean less than that at Browns River. . The low-monthly temperature and 95% confidence tide average temperature and 95% confi-interval at low tido over all years ranged dence interval from 1980 to 1992 was 10.1 from 1.1 1 0.4*C in January to 22.0 t i 1.0'C (Table 9-2). Mean low-tide 0.9"C in July during the study period temperature in 1992 (9.1'C) was the (Table 9-1, Figure 9-2) . In 1992, monthly coolest during the thirteen-year study temperatures were near average (within the period (since 1980). Likewise, the 1992 95% confidence limits of the overall annual mean temperature at high tide was years' average) for eleven months and at an all-time low (8.6'C), although it above average only in August (Figure 9-2), was just within the 95% confidence limit The annual mean temperature in 1992 was for the average. In 1992, the offshore within 95% confidence limits of the surf ace water temperature was also cooler average for the thirteen-year study period than normal (Section 2.0). (Table 9-2). The bottom substrate type at subtidal stations was generally fine sand with organic carbon ranging from 1.0 to 2.7%. ! At intertidal stations, the sediment usually varied between fine sand and silt l 1 9-4 j l
ESTtJARINE BENTil0S TABLE 9-1. EAN MONTELY SEAWATER SURFACE SALINITY (ppt) AND TEMPERATURE ('C) TAKEN IN BROWNS RIVER AND HAMPTON HARBOR AT HIGH AND LOW TIDE, MAY 1979 DECEMBER 1992. SEABROCK OPERATIONAL REPORT, 1992. SALINITf BROWNSRIVER BAMPTON HARBOR HIGHTIDE LOW TIDE HIGH TIDE LOW TIDE MEAN Cl MEAN Cl MEAN CI MEAN Cl JAN 31.5 0.5 22.7 2.1 31.9 0.7 28.5 1.2 FEB 29.8 1.6 19.4 2.3 31.6 0.5 27.4 1.7 MAR 29.2 1.2 17.9 2.3 31.2 0.7 26.2 1.8 l l APR 27.4 2.0 17.1 2.8 30.1 1.0 24.7 2.2 MAY 28.9 1.4 19.5 2.4 29.9 0.7 26.4 1.2 JUN 29.1 1.2 21.4 2.0 29.8 1.4 27.2 1.9 JUL 30.1 0.7 24.0 1.2 30.9 0.5 28.8 0.6 , AUG 29.8 0.8 24.5 1.5 31.2 0.3 29.2 0.7 SEP 30.6 0.8 24.1 1.8 31.4 0.3 29.4 0.7 l l OCT 30.3 0.8 22,9 1.4 31.5 0.3 29.0 0.6 ! Nr# 29.5 12 19.7 2.4 31.6 0.3 27.9 1.0 DEC 30.5 1.2 20.4 2.6 31.8 0.5 27.7 1.5 l TEMPEFATURE BROWNS RIVER HAMPTON HARBOR HIGH TIDE LOW TIDE BIGH TIDE LOW TIDE EAN Cl MEAN Cl EAN CI EAN Cl JAN 1.9 1.0 1.1 0.4 2.8 0.6 1.1 0.5 FEB 2.0 0.8 1.9 0.6 2.7 0.6 1.9 0.6 HAR 4.4 0.8 5.4 0.6 3.7 0.4 4.3 0.6 APR 7.3 0.7 9.6 0.5 6.2 0.6 8.2 0.5 MAY 12.9 1.3 14.6 0.7 10.1 0.6 12.5 0.7 Jt1 16.4 0.9 19.5 0.7 13.5 0.5 16.3 0.6 JUL 18.3 0.7 22.0 0.9 15.7 0.5 18.4 0.6 AUG 19.1 0.7 21.4 1.1 16.9 0.7 18,7 0.6 SEP 16.4 0.8 18.2 0.8 14.6 0.7 16.3 0.6 0CT 11.9 0.7 12.6 1.1 11.9 0.6 12.0 0.6 NOV 8,3 0.6 7.6 1.1 8.9 0.5 8.1 0.7 DEC 4.7 1.0 2.5 0.9 5.3 0.6 3.5 0.8 { 9-5
ESTUARINE DENT 110S TABLE 9 2. ANNUAL MEAN WIT 8 95% CL FOR TEMPERATURE ('C) AND SALINITY (ppt) TAXEN AT BCfrH RICH AND LOW SLACK T!DE FRON BROWNS RIVER AND HAMPTON HARBOR FRCN 19 W 1992. SEABROOK OPERATIONAL REPORT, 1992. BROWNS RIVER LOW TIDE HICHTIDE b b CL SALINITY CL TEMPERATURE
- CL SALINITY
- CL TEMPERATURE 10.9 5.2 25.1 1.9 9.6 4.4 31.0 1.6 1980 10.6 4.4 25.5 1.6 10.3 4.6 30.0 1.7 1981 10.7 4.5 22.8 1.8 9.9 4.1 30.0 1.2 1982 11.9 5.0 19.4 3.6 11.0 4.2 28.0 1.9 1983 11.9 5.1 18.1 3.3 10.6 3.9 28.4 1.8 1984 11.3 5.0 21.7 2.1 10.1 4.4 30.6 0.7 1985 10.3 4.8 20.4 3.1 9.6 4.0 30.2 0.9 1986 11.5 5.1 20.6 2.6 9.6 4.1 28.9 1.8 1987*
10.6 5.1 20.5 2.2 10.3 4.0 29.8 0.7 1988 11.5 5,4 20.2 2.5 10.1 3.9 30.0 0.7 1989 5.3 19.5 2.7 10.9 4.5 29.6 1.4 1990* 12.6 12.4 5.0 19.4 1.9 11.7 4.1 29.6 1.3 1991 11.7 5.2 21.9 1.5 11.1 3.7 29.6 0.8 1992 OVEFALL' 11,4 1.2 21.2 0.7 10.4 1.0 29.7 0.3 BAXPTON HARBOR LOW TIDE HIGH TIDE b b CL SALINITY CL TEH?ERATURE* CL SAMNITY* CL TEMPERATURE 9.6 4.4 29.9 1.4 9.1 3.6 32.0 0.5 1980 10.1 4.4 28.9 1.1 9.3 3.8 31.5 0.4 1981 10.2 4.1 27.3 1.5 9.2 3.5 31.2 0.6 1982 10.4 4.3 25.5 2.4 9.9 3.4 30.1 0.9 1983 10.4 4.1 25.8 2.3 9.4 3.1 30.2 0.9 1984 10.6 4.2 29,1 1.0 10.1 3.3 32.2 0.3 19&5 10.0 3.9 27.7 1.3 9.4 3.0 31.5 0.4 1%6 1987 10.0 4.3 27.5 2.2 8.9 3.5 30.7 0.9 9.7 3.9 27.8 1.0 9.2 3.3 31.3 0.4 1988 10.2 4.4 28.0 1.2 9.2 3.3 31.4 0.7 1989 10.3 4.3 27.2 1.2 9.7 3.6 31.3 0.6 1990 11.1 4.0 28.0 0.9 9.8 3.1 30.9 0.4 1991 9.1 4.0 27.2 1.6 8.6 2.9 29.4 1.6 1992 10.1 1.0 27.7 0.4 9.4 0.8 31.1 0.2 OVERALL
" Annual mean rean of 12 conthly means. except for Browns River in 1987 and 1990 when January and February monthly reans were estimated by using the monthly mean over all years frca 1980-1990.
Nonfidencellaitsexpressedashalftheconfidenceinterval. Overall mean mean of monthly means. 9-6
ESTUARINE BENTH05 with organic carbon ranging from 1.6 to since major changes often occurred 5.9% (NAI 1985). simultaneously in both Browns River and Hill Creek. Densities at all stations from 1992 fell between the high densities i 9.3.2 Macrofaung which usually occurred from 1980-82 and the low densities which of ten occurred in The subtidal and intertidal benthic 1984 and 1987 (Table 9-4). communities in Browns River (just down-l stream of Seabrook Station's Settling The mean number of taxa collected Basin discharge) and M111 Creek (away from annually at each of the four stations the discharge) were examined to determine ranged f rom 16 to 47 during the fourteen- - - - - - temporal and spatial trends. Spatial dis- year study period. Annual variations in tribution of organisms at both locations the number of taxa were significant at was very patchy, and large population three of the four stations (Tabics 9-3,4). fluctuations occurred among sampling In 1992, the number of taxa increased periods (NAI 1987) as is typical in estu- slightly over 1991 values at each station, arine habitats. The most numerous species and like densities, fell between the high inhabiting estuaries are those that are numbers that of ten occurred from 1980-82 resistant and resilient to natural changes and the generally lower numbers in 1984 in the physical environment, such as and 1987. Annual changes in the number fluctuating salinity, sediment grain size of taxa generally followed the same and temperature. The polychaete Streblos- pattern at all four stations for most of plo bonodlett was the most abundant the study period (1978-1992). species in the estuary, and constituted 7 to 9% of the total geometric mean den- Streblospio benodleti is a cosmopolitan, sity at both subtidal stations, and 13 to opportunistic polychaete (Grassle and 22% of the total density at both intertid- Grassle 1974), and one of the first to al stations when averaged over all years colonize after a perturbation of the (Table 9-3). 011gochants and Capitella environment (Rhoads et al. 1978). Ex-capitata were also present in very high tremely high densities could occur during numbers. The clam worm Fediste diver- any season at both intertidal and subtidal sicolor was very abundant intertidally in stations, but were rarely sustained into Browns River. The sof t-shelled clam, Nya the next sampling period, causing tremen-arenarla, was also present in substantial dous population fluctuations and wide numbers at both sampling locations, confidence limits for the annual mean (NAI especia11y Hill Creek (Table 9-3). 1987). With such high seasonal variation, no significant differences among years Total unsity (number of individuals /m') were found at three out of four stations. of all macrofaunal organisms showed Population decreases in some years significant year-to-year variations during (particularly 1987, Table 9-3) coincided the fourteen-year study period (Tables 9- with observed low weekly salinities (NAI 3,4). These variations appear to be 1987), which may have impeded recruitment. related to crea-wide environmental trends, In 1992, densities decreased greatly from 9-7
l TABLE 9-3. HEAN NUMBER OF TAIA AND THE GE0 METRIC MEAN DENSITY (No./mE ) FOR EACH YEAR AND OVER AI.L YEARS WITH 951 CONFIDENCE LIMITS FRCH ESTUARINE STATIONS AT 8ROWNS RIVER (3) AND MILL CREEK (9) SAMPI1D FROM 1978 THROOCE 1992 (EICL:: DING 1985). SEASROOK OPERATIONAL REPORT,1992. ALY YFAR$* STATION 1978 1979 1920 1981 1922 1983 1984 1986 1987 1988 1989 1990 1991 1992 MEAN UPPER Lon(ER l l
- Total Density
- 3 3170 4616 4978 5360 9331 2635 1244 1182 1198 3472 2583 1707 1889 2253 2701 3434 2125 l 9 3619 2209 14,767 11,277 4335 4533 620 2819 726 4764 1878 2488 5373 2178 3130 4428 2212 '
l , 3MLV 4260 6136 5695 6833 8022 2723 2187 5632 1727 3936 6940 1778 6834 4842 4309 5362 3462 3120 4512 6947 12.189 11,383 11,151 5131 4203 653 6115 7525 3345 3572 4997 5035 6871 3690 (. 9MLW 7344 8424 7796 4364 1715 2980 995 4467 3990 2321 3967 3301 3680 4244 3191 l MEAN 3514 4099 Mean No. of Taxa
- 3 35 41 38 42 47 32 27 38 33 38 38 35 32 34 36 39 34 9 26 34 47 44 34 36 21 36 21 27 25 31 30 31 32 34 29 6
3MLW 28 37 31 38 35 28 18 32 23 31 31 28 25 26 29 32 27 o 9MLW 28 35 35 41 36 33 21 36 16 29 29 36 25 33 31 34 28 29 37 38 41 38 32 22 35 23 31 31 33 28 31 32 33 31
& MEAN Streblospio 3 367 123 193 525' 1064 552 239 99 66 550 181 56 462 160 237 349 161 benedicci 9 106 -26 2396 525 81 538 16 161 49 744 167 400 1612 296 217 419 112 3MLW 439 505 1010 928 3584 525 535 1421 316 1306 3227 259 3301 1635 959 1403 656 9MLV 566 434 466 2700 2354 3215 1560 1299 11 744 399 1023 604 231 648 1136 369 MEAN 314 163 684 912 925 842 242 415 58 794 445 278 1105 366 423 552 324 Oligochaeta 3 242 270 204 651 2189 556 225 95 133 768 301 156 233 421 318 456 222 9 16 100 2910 969 1058 1603 162 528 131 272 233 260 525 293 336 548 206 3MLV 87 186 318 320 350 292 382 968 215 322 409 48 197 428 262 389 177 9MLW '574 810 1067 861 565 2877 572 742 161 351 2838 362 610 2024 760 1184 488 MEAN 119 253 671 646 823 931 298 437 157 392 537 163 348 572 382 474 308 Capicalla 3 11 63 123 473 889 216 66 73 57 105 72 16 33 153 87 145 52 capiraca 9 238 29 2453 277 291 376 28 808 113 1530 262 259 479 220 276 446 171 I 3MLW 17 29 138 244 540 208 124 197 26 46 27 24 10 57 65 101 42 9MLW 279 45 125 320 276 800 303 234 19 1068 173 466 143 181 211 332 135 MEAN 60 40 269 318 443 341 91 228 42 299 98 84 71 137 135 173 106 (coatinued)
TABII 9-3. (Costinued) M_1. YT_a gse STATION 1978 1979 1980 1981 1982 1983 1984 1986 1987 1988 1589 1990 1991 1992 PJ. Ass UPPER 12WER Kodisca 3 83 172 158 352 452 45 50 52 43 128 52 38 64 50 87 122 62 darersicolor 9 21 29 41 205 41 7 7 43 2 33 29 8 45 35 24 37 15 l 3tfLV 800 1343 1169 1613 975 220 296 987 150 523 1235 199 1906 1105 667 1017 464 9ttIM 170 164 101 241 6 93 46 135 57 513 184 29 18 30 25 73 116 ffEAN 125 133 167 410 223 45 89 143 18 90 115 33 115 84 102 134 77
#pa arenaria 3 69 158 92 181 132 15 31 21 30 12 35 64 7 17 45 68 29 427 246 9 265 299 148 168 157 34 53 83 69 208 48 32 119 173 82
- 32fIM 106 224 26 179 117 103 22 13 27 12 73 25 22 31 46 71 29 e 9fflM 100 328 62 400 141 70 86 13 73 39 425 266 102 107 109 162 74 tEAN 118 265 82 237 134 98 55 19 42 26 93 98 30 37 72 89 58 Spio secosa 3 38 39 65 155 159 120 113 15 1 171 244 447 334 376 267 150 209 109 9 50 59 287 346 170 16 3 75 6 315 23 110 158 66 73 114 40 3tfLV 7 9 8 6 4 8 2 46 25 46 2% 26 8 2 10 17 6 9tiLV 54 59 43 78 48 30 8 65 2 32 41 117 46 5 31 54 18 MEAN 30 33 51 72 51 26 10 76 16 104 102 103 70 22 44 59 33 Cauflarialla 3 330 221 835 1 2 3 12 9 1 101 7 6 24 10 18 37 8 sp. B 9 10 40 46 292 136 35 7 10 3 16 4 4 75 27 22 44 11 3!!IM 106 174 607 3 23 52 44 255 87 244 80 28 4 9 52 96 28 9MIM 8 298 48 43 1634 278 325 307 1 21 3 8 8 22 42 92 19 ffEAN 42 147 183 17 64 37 34 53 5 54 10 9 16 15 30 43 21 bYearly mean density = mean of three seasonal means (where seasonal mean = sean of five replicates)
Yearly mean number of taxa = mean of three seasonal totals (where seasonal total = total number in all five 1/16 m2 g replicates combined). In August 1992 at Station 3?i1M, the total number of replicatas was four, not five. All years' mean = mean of 39 seasonal means (3 seasons a 14 years)
-r
TABLE 9-4. RESULTS OF ONE-WAY ANALYSIS OF VARIANCE AMONG YEARS FOR THE MEAN hvMBER OF TAXA 2 (per S/16 m ) 2AND LOO (x+1) TRANSFORMED DENSITY (No./m ) 0F THE MOST ABUNDANT ESTUARINE SPECIES AND THE TOTAL DENSITY OF MACROFAUNA COLLECTED AT ESTUARINE STATIONS FROM 1978 THROUGH 1992 (EXCLUDING 1985). SEABROOK OPERATIONAL REPORT, 1992. PARAMETER
- STATION Fb HULTIPLE COMPARISONS * - SUBTIDAL STATIONS Total Density 3 3.61** (79-82,68)>(78,83-84,86-92) 9 3.19** (78,80-83,88,91)>(79,84,86-87,89-90,92)
Number of Taxa 3 1.91 NS 9 4.93*** (80-81)>79,82-83,66(78,84,87-89,90-92) f Streblospicn benedicti 3 1.96 NS g 9 1.83 NS Oligochaeta 3 1.43 NS 9 4.06 * (80-83,86,91)>84,87-90,92(78-79) Capite11a capitata 3 2.03 NS 9 3.69** (80,83,86,88,91)>78,81-82,89-90,92(79,84,87) Sediste diversicolor 3 2.42*' (78-82,88)>(78-80,83-84,86-92) 9 2.32* (78-82,86,88-89,91-92)>(78-79,83-84,87-90) Mya arenaria 3 2.22* (78-84,86-87,89-90,92)>(78,83-84,86-92) 9 1.95 NS Spio serosa 3 2.34* (81-84,86-92)>(78-84,86) 9 2.30* (78-83,86,88-92)>(78-79,83-84,86-87,92) Cau11 erie 11a sp. B 3 5.49*** (78-80,88)>91(81-84,86-87,89-90,92) 9 1.11 NS (continued)
l TABLE 9-4. (Continued) STATION 6 HULTIPLE COMPARISONS * - INTERTIDAL STATIONS PARAMETER
- 1 Total Density 3MLV 2.52* (78-83,86,88-89,91-92)>(78,83-84,87-88,90,92) 9MLV 2.30* (78-84,86,88-92)>(78,87,91)
Number of Taxa 3MLV 2.85** (78-83,86,88,90)>(78,83-84,87,90-92) 94LV 2.73* (78-83,86,88-90,92)>(78,84,87-89,91) i Streblospio benedicti 3MLV 2.06 NS 9MLV 2.94** (78-84,86,88-92)>87 Oligochaeta 3MLV 0.97 NS I 9MLV 0.96 NS I
'f Capire11a capitata 3MLV 4.25*** (80-84,86)>(78-79,87-92)
[ 9MLV 2.05 NS Hediste diversicolor 3MLV 1.60 NS 9MLV 3.55** (78-82,84,86,89)>83(87-88,90-92) Mya arenaria 3MLV 1.75 NS l 9MLV 2.46* (78-84,87,89-92)>(78,80,83-84,86-88,91-92) Spio setosa 3MLV 1.14 NS 9MLV 1.24 NS Cau11eriella sp. B 3MLV 3.17** (78-80,83-84,86-89)>(81-84,90-92) 9MLV 3.74** (79,82-84,86)>81(78,87-92)
" Degrees of freedom for the model (years) = 13 Degrees of freedon for the error = 28 b NS = Not significant (p>0.05) j * = Significant (0.05>p>0.01)
** = Highly significant (0.01>p>0.001)
*** = Very highly significant (p50.001)
- Multiple comparison test is Valler-Duncan k-ratio e test with alpha = 0.05. Groups are in order of decreasing abundance. Statistically similar groups that include either the years of highest or lowest values are placed within parentheses. Intermediate years may overlap with the highest and/or lowest groups.
I
ESTUARINE BENTIIOS 1991 at all four stations, although they fresh and salt water (Pettibone 1963).
were well within'the range of previous It is an omnivore, frequently abundant in years. When averaged over all years, in- nutrient-rich areas, and has been consid-tertidal densities were at least 3 times ered an opportunist and an indicator of higher than subtidal densities (Table 9- pollution (llull 1987). Both intertidal 3), and subtidal stations at Browns River had substantially higher densities than The class Oligochanta is a species stations of comparable depth at Hill complex that is very abundant in the Creek. Intertidal stations had higher estuary, with no evidence of annual densities than subtidal stations (Table trends. The seasonal cycle of oligo- 9-3), particularly Station 3MLV in Browns chantes indicated that peak densities River. Significant differences among occurred during every season (NAI 1987), years occurred at all stations except but were not sustained. No consistent Station 3HLW, where E. diversicolor was differences in densities were found consistently most abundant (Table 9-4).
between Browns River and Hill Creek Densities at Station 3HLW peaked in 1991 stations (Table 9-3). Likewise, no and remained above average in 1992. At significant differences occurred among the other three stations, densities in years, except at Station 9 (Table 9-4). 1992 were near or slightly below average, When examining the yearly densities, and well within the range for the study -
population fluctuations were not consis- period (Table 9-3),
tent, probably because they were repre-sented by more than one species. Densi- Nya arenarla, the soft-shelled clam, had ties in 1992 were well within the range important recreational value until 1989, for the study period (Table 9-3). when llampton liarbor flats were closed due to co11 form contamination (Section 10.0).
The opportunistic polychaete Capite11a Young-of-the-year (50 mm) #ya arenaria at Hampton-Seabrook Harbor l
Flat 4 from 1974-1992 . . . . . . . . . .. ...... . . . . . 10-4 l
i 10-5. a. Mean monthly catch per unit effort log (x+1) and 95%
confidence intervals for green crab (Carcinus mannas) collected during preoperational years (1983 1989) and operational years (1991 and 1992) and b. Mean fall (October-December) catch per unit effort for green crab in Hampton-Seabrook Harbor and its relationship to minimum winter temperature f rom 1978-1992 . . . . ...... .. . . . . . 10-9 10-6. Number of clam licenses issued and the estimated bushels por acre of adult (>50 mm) clams in Hampton Seabrook estuary, 1971-1992 . . . . . . . . . . . . . . . . . ... ,. . . . . . 10-9 LIST OF TABLES 10-1. GE0 METRIC MEAN DENSITY (NUMBER PER CUBIC METER LARVAE; l- NUMBER PER SQUARE FOOT JUVENILE / ADULTS) AND LOWER AND UPPER 95% CONFIDENCE LIMITS (LCL,UCL) 0F NYA ARENARIA COLLECTED DURING PREOPERATIONAL YEARS AND 1991, 1992 AND OPERATIONAL MEANS . . . . . . . . .. . . ..... ... . . . . . 10-5 10-2. RESULTS OF ANALYSIS OF VARIANCE COMPARING #YA ARENARIA LARVAL. SPAT. JUVENILE AND ADULT DENSITIES DURING PREOPERATIONAL AND OPERATIONAL PEEIODS . ..... .. . . . . . . 10-6 10-3.
SUMMARY
OF EVALUATION OF EFFECTS OF OPERATION OF SEABROOK STATION ON SOFT-SHELL CLAM . . . . . . . ......... . . . 10-12 10-11 a--____-____.
80VT-81tBLL CLAH (NYA ARENARf A) I 10.0 SOFT-SifELL CLAH (NYA ARENARIA) buf fered formalin (with sugar added to enhance color preservation) and ref riger-10.1 QRECTIVES ated. In the laboratory, samples were I split when the total umboned bivalve The objective of the soft-shell clam larvae count exceeded 300 specimens and monitoring program is to determine the two subsample fractions were enumerated potential ef fects due to the operation of from each sample. A more detailed Seabrook Station on seasonal, spatial, and description of methods can be found in NAI annual trends for various life stages of 1991. sof t-shell clams in Hampton Harbor NH, if any. The potential effects include dis-charge of Seabrook Station's Settling 10.2.2 }1 panton Harbor Survey l Basin into Browns River as well as ) Seabrook Station's intake and discharge The five largest flats in the Hampton-of once-through cooling waters. Other Seabrook estuary (Figure 10-2) were l l factors that affect the population size surveyed in the late fall from 1974-1992 such as predation and disease have been to obtain information on clams raeusuring considered. Nearfield/farfield compari- at least 1 mm. Pre-selected stations for sons are made between the Hampton Harbor each fint were chosen. The number of sta-and an adjacent estuary, Plum Island tions sampled on each flat was determined Sound, Ipswich MA. on the basis of the variance in density observed at that flat. Flats 3 and 5 were not sampled for adults, since adult 10.2 liFJ1 LODE density has historically been low. 10.2.1 Bivalve Larvae A sample for 1-25 mm clams consisted of three 10.2-cm diameter x 10. 2-cm deep The spatial and temporni distributions cores (4" diameter x 4" deep) taken within of 12 species of umboned bivalve larvae a 30-cm x 61-cm quadrat (1-ft x 2-ft). including Nya arenarla were monitored Sampics were sieved with a 1-mm mesh using a 0.5-m diameter, 0.076-mm mesh net. sieve, and clams were enumerated, mea-Samples were collected weekly from mid- sured, and released. A sample for clams April through October at Hampton Harbor 226 mm consisted of one quadrat dug to a (P1), intake (P2), discharge (PS) and depth of 45 cm (1.5 f t) with a clam fork. farfinld (P7) stations (Figure 10-1). Large clams were removed f rom the sediment Sampling began at Station P2 in July 1976. in the field, enumerated, measured, and Station P7 was added in 1982, and Station released. l P1 was added in July 1986. Collections were made at Station PS from July-December 1986 and April 1988 to the present. Two 10.2.3 Nearfigid/Farfield Study simultaneous two-minute oblique tows were taken at each station. Upon recovery, not To compare population densities of seed contents were preserved with 1-2% borax- clams (1-12 mm), surveys were conducted 10-1
N k g . . .
,ous
.U .\
\
4 h 8 Aktmeeners AR A cc rI e..o's.ava . cau,rgous ,
"Eu7E LEGEND 1 :
} .,
88lj7 .
- = Bivalve Larvae Stadons i hw. ** P1,P2,P5,P7 stas ook lg , h.; \'Olsenege
[ "$NE a T ATiCN s"$Noo"e uaz ausoa as 9 N ,, '9:::" -
\/
uuuvar nuh Figure 101. Bivalve larvae (including Mya arenaria) sampling stations. Seabmok Operational Report,1992. Wrerohw N 1 KD'
%f 9-D u ntero.v "E^'"
i seebrook statkn Ep [sf8* LEGEND O = Clam Flats (.~0 ? g . or n crao j$ D*# 8 g.m r .. i
,,, %j JOj , .:
l 6 -
/ [> uunen ats l anu.csssa ,
c Qp SEABROOK BFACH Figure 10-2. Itampton Scabrook estuary soft-shell clam (Mya arenaria) and green crab (Carcinus maenas) sampling areas. Seabrook Operational Report,1992. 10-2
- au---- - - _ - _ - _ _ _ _ _ _ _ . _ _ _ _ _ _ . . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
SOFT-SHELL CLAM (#YA fRENARIA) in the f all at 10 stations lu both Hampton In addition, the interaction between Harbur and Plum Island Sound beginning in station cr area and period was investigat-1976. Collections were also made in ed. If the interaction term (Preop-Op X Ogunquit, ME from 1976-1984. Three cores Area) was found significant, the least, were taken per station and processed using squares means procedure (SAS 1985) was the same methods employed in the Hampton used to determine the parameters that were Harbor survey described above. An addi- significantly different at the alpha 5 tional 1-cm deep x 35-mm diameter core was 0.05 level. Details of the ANOVA model taken for analysis of newly-set sof t-shell are provided in NAI (1992). Analysis of clam spat (<1,0 mm) . Sampling sites were variance utilized densities compute > > , , , i
. . i e i i i , i e 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 APR MAY JUN JUL AUG SEP OCT Figure 10 3. Weekly mean and 95% confidence interval forlog (x+1) density (no. per cubic meter) of Afya arenaria larvae at Station P2, dunng the preoperational (1978-1989) and operational (1991 and 1992) periods and in 1992. Seabrook Operational Repon,1992.
s I y 10 ,o K h %*]*, K\.
'~
/,-
6 C%%* 0 , i, '9 , ,,4 0.0 ",. D. , , ' /sh, O
?,
*c 0V *.1 .-0s,g" - ,;' s' t.5 ** s o p1 nuY . s,'r ),
16 6 p,p ** g
- > Closure of Hamptre liarbor to clam barvesting.
l Figure 104. Annual log (x+ 1) mean density (number ;cr square foot) of yotmg-of the. year (1-5 mm), spat (6 25 inm), juvenile (26 50 mm), and adult (>50 mm) Aff a arenaria at Hampton Seabmok HarborPlat 4 from 1974-1992. Seabmok Operational Repon,1992. 10-4
TABLE 10-1. GEOMETRIC MEAN DENSITY (NUMBER PER CUBIC METER, LARVAE; NUMBER PER SQUARE FOOT JUVENILE / ADULTS) AND LOWER AND UPPER 957. CONFIDENCE LIMIT 3 (LCL,UCL) 0F NYA AVENAVIA COLLECTED DURING PREOPERATIONAL YEARS AND 1991, 1992 AND OPERATIONAL MEANS. SEABROOK OPERATIONAL REPORT, 1992. PREOPERATIONAL" OPERATIONAL LIFESTAGE AREA LCL MEANb UCL 1991 1992 MEANb Larvae P2 4.2 5.4 7.0 3.4 3.9 3.6 PS 3.0 5.0 8.1 6.4 2.6 4.1 P7 4.1 5.7 7.9 3.4 4.8 4.1 1-5 m HH-1 2.0 3.5 6.0 1.5 1.5 3.4 young-of- HH-2 3.7 8.6 18.0 3.2 1.4 4.2 the-year 101- 4 5.5 10.5 19.0 1.4 1.5 3.3 ALL 3.4 6.4 11.4 2.0 1.4 3.7 5 6-25 m 101- 1 0.4 1.7 4.3 0.2 0.4 1.0 s " spat 101- 2 0.1 0.7 1.7 <0.04 0.3 0.3 101- 4 1.2 3.4 8.0 0.2 1.0 1.4 ALL 0.5 1.8 4.0 0.1 0.5 0.8 26-50 m 101- 1 0.5 1.6 3.5 0.7 0.4 0.4 juveniles HH-2 0.1 0.4 0.7 0.1 0.1 0.1 HH-4 0.6 1.7 3.7 0.9 0.6 1.0 ALL 0.5 1.2 2.2 0.5 0.3 0.4
>50 mm 101- 1 0.3 0.6 1.0 0.6 0.8 0.6 adults HH-2 0.2 0.4 0.7 0.1 0.3 0.2 101- 4 0.3 05 0.8 1.4 2.3 1.9 ALL 0.3 0.5 0.8 0.5 0.8 0.6 1-12 m Hampton liarbor 0.0 5.7 9.1 3.3 3.3 4.5 spat Plum Is. Sound 7.6 17.1 36.9 7.7 3.2 9.9
- Ilamoton Larvae PREOP = 1988,I 1989; Harbor-Plum OF = 1991, 1992. Hampton Harbor (101) PREOP = 1974-1989; OP = 1990-1992.
- s. PREOP = 1987-1989; OP = 1990-1992 b
PREOP and OP means = mean of annual means. '
TABIE la-2. RESULTS OF ANALYSIS OF YARIANCE COMPARING N/A R EN RIA 1ARVAL, SPAT, JUVENILE AND ADULT DENSITIES DURING PREOPERAYIOPAL AND OPERATIONAL PERIODS, SEABROCK OPERATIONAL REPORT,1992. SOCRCE OF , LIFESTAGE STATION / FIAT MRIATION df SS T MULTIPLE COMPARISONS * (in decreasing order) Bra arenaria Nearfield (P2, PS) Preop-Op**d 1 0.34 1.39 NS larvae" Farfield (P7) Year (Preop-Op)* 2 1.88 3.79* Week (Proop-Op X Year), 41 - 48.37 4.77*** Stations 2 0.45 0.91 NS Pre (p-Op X Station" 2 0.60 1.22 NS Error 86 21.28 MAMPTON MARECR 1-5 mmb 1,2,4 Preop-Or. I 13.70 31.30*** young-of- Year (Preop-Op) 17 193.59 26.02*** the-year Area 2 11.54 13.18*** Preop-Op X Area 2 7.80 8.91*** 4 Pre 2 Pre 2 Oo 1 On 4 09 1 Pre Error 1483 649.13 6-25 me" 1, 2, 4 Preop-Op 1 6.92 29.70*** Op<Proop spat Year (Proop-Op) 17 197.59 49.86*** Area 2 12.82 27.50*** 4>1>2 Preop-Op X Area 2 1.41 3.03 NS Error 1483 345.72 - 26 -50 een" 1, 2, 4 Proop-Op 1 9.23 57.55*** Op<Proop o juvenile Year (Proop-Op) 17 191.97 70.39***
- Area 2 16.69 52.03*** 421>2
- Proop-Op I Area. 2 0.87 2.71 NS Error 2583 414.37
>50 mm 1, 2, 4 1 1.26 22.04***
adult. Proop(-Op Year Preop-Op) 17 35.51 36.45*** 1egal Area 2 9.36 81.70*** Preop-Op X Area 2 6.72 58.60*** 4 Op 1 Pre 1 Op 4 Pre 2 Pre 2 Op Error 2583 148.03 NEARTIELD/FARFIEIE 0.71 1.34 MS 1-12 me" Hampton Harbor Proop-Op 1 4.73 2.25 NS Plum Island Sound Year (Preop-Op) 4 4.03 7.66** Farfield> Nearfield Area 1 0.13 0.24 NS Proop-Op X Area 1 58.94 Error 112
" Larval comparisons based on weekly samp1tng pericds, utd-April through October; where preop = 1988, 89 and op = 1991, 92. "For Hampton Harbor Survey preop = 1974-89 and op = 1990-92. -For the Nearfield/Farfield Survey NS = Not significant (p>0.05) preop = 1987-89 and op = 1990-92. * = Significant (0.052p>0.01)
- Commercial operation began in August 1990, therefore the operational period includes 1990 for ** = Highly significant (0.012p>0.001) spat.- Juveniles, and adults, but not for larvas. *** = Very highly significant (0. 0012p) dOperational versus preoperational period regardless of area.
" Year nested within preoperational and operational periods, regardless of area. ' Week nested within year regardless of area.
- Station or flat, regardless of year or period.
IInteractionofmaineffects.
' Underlining signifies no significant' differences among least square means at alphs 5 0.05.
.. , - - .- . - - - _ - ~
SOFT-SHELL CLAH (MYA ARDIARTA) which affect spawning in addition to flats (Tables 10-1, 10-2). Densities in
-temperature include adult condition and 1992 were similar to those in 1991, and food availability (Newell and Hidu 1986). much lower than the high values noted in
-Larval abundance is dependent upon the 1990 (NAI 1992). Historically, spat number of adults spawning, the location density has had a high natural vari-of spawning sites, coastal currents, water ability, and 1992 was within the range of column stratification and larval behavior. previous years (Figure 10-4 and NAI 1992) .
Average abundances for the operational Length of life spent in the larval state period showed a significant decrease at is approximately 12 days at 20*C, but Flats 2 and 4 when compared to the average lasts up to 21 days at cooler conditions for the preoperational period, but showed (Turner 1949) . Larval abundances in 1992 no change at Flat 1 (Table 10-2).
,harply increased in July coinciding with water temperatures that averaged 15.2*C.
Planktonic larvae settle to the bottom Sont (6-25 mm) and Juveniles (26-50 mm). after this period, attach to the bottom Trends in the 6-25 mm size class indicate
- substrate to become spat, and remain as the survival success of young-of-the-year j bottom dwellers. (1-5 mm spat) . During 1992, recraftment into the 6-25 mm size class increaued over Gonadal studies have demonstrated that the previous year, but remained below the ;
the onset of spawning in Hampton Harbor preoperational mean at all three flats and Plum Island Sound (late May-June) (Table 10-1, Figure 10-4) . As a result, usually follued the appearance of larvae average densities of 6-25 mm clams during in of fshore tows (early-mid May). There- the operational period were significantly fore, the spring and early summer larvae lower than preoperational averages at all population may originate further-south three flats (Tables 10-1, 10-2). Differ-(NAI 1985). This implies that these off- ences among years and flats were also sig-shore larval peaks may in part have a more nificant. Flat 4 had significantly higher southern origin. The late-summer peaks densities of 6-25 mm clams than Flat 1, had been observed to be coincident with which in turn had significantly higher northward-flowing currents. Recruitment densities than Flat 2. of larvae of non-local origin is likely due to currents in the Gulf of Maine, Juvenile (26-50 mm) densities in 1992 which may move water masses and their en- remained well below the preoperational trained larvae significant distances mean, decreasing slightly from 1991 levels before larval settlement (NAI 1979). at Flats 2 and 4 (Table 10-1). Average operational densities were significantly lower than the preoperational mean at all 10.3.2 Hamoton Harbor Survey three stations (Table 10-2). However, spatial differences were consistent with youne-of-the-year (1-5 mg11 In 1992, . historical trends, as was true with the spatfall of 1-5 mm clams was well below spat. Flat 4 had significantly higher the preoperational average at all three densities than Flat 1, which in turn had 10-7
i SOFT-SHEl.1, CIAH (#YA ARENARIA) significantly higher densities than Flat - 10.3.4 Effects of Predation and 2 (Table 10-2), Perturbation Clams in Hampton Harbor have histori-Mults D50 mm). Clams measuring more cally been subjected to predation pressure than 50 mm are at least 4 years of age from two major sources: green crab-( Ayor 1968) and considered adults in this (Carcinus maenas), which consume spat (1-study. In 1992, densities of adults were 25 mm) and juvenile (26-50 mm) t;ya (Ropes h1gher than 1991 densities at all three 1969), and humans who dig adult Nya and flats (Table 10-1). Flat 4 showed the also cause mortality to smaller clams largest increase, and reached the highest following flat disturbance. Sea gulls may density to date since the study bogan in also be major predators, as ' they are 1974 (Figure 10-4) . The average density commonly observed picking over clam digger at Flat 4 during the operational period excavations for edible invertebrates, was significantly higher than durin. the preoperational period; however, there was Clams are a major source of food for no significant difference in average green crab, particularly in the fall density during the operational period at months (Ropes 1969). Maximum green crab Flats 1 and 2 (Tables 10-1, 10-2). abundance usually occurred in the late fall (Figure 10-5a). Mean densities-during the 1991 - 1992 operational period 10.3.3 Nearfield/Farf,leid Study were higher than preoperational densities in three out of ten months. Densities of #ya (1-12 mm) in 1992 were within the 95% confidence limits of the Welch (1969) and Dow (1972) found that preoperational ( 1987-1989) average at the green crab abundance increased markedly nearfield area (Hampton Harbor), but were following relatively warm winters. Data well below the preoperational average at from Hampton Harbor from the past 15 years the farfield aren (Plum Island Sound) for the most part corroborate their (Table 10-1) . A comparison of mean densi- findings (Figure 10-5b) although there are - ties at nearfield and farfield stations exceptions. During the winters when the during the operational (1990-1992) and minimum temperature was relatively high preoperational (1987-1989) periods indi- (1983-1989), green crab abundance in the cates, however, that #ra has been signifi- following fall was also high (Figure 10-cantly more abundant at Plum Island Sb). In 1990, when the minimum winter throughout the study (Tables 10-1, 10-2). temperature was relatively low, green crab Although average densities within Hampton abundance was also low. However, in 1992 Harbor and within Plum Island Sound in the minimum temperature was low, but the 1992 and for the operational period were fall green crab abundance was at its ! lower than the preoperational average, highest level to date. It is likely that this difference was not significant (Table other factors such as competition are 10-2), involved in controlling the population size of green crab. 10-8 1
- a. Monthly Catch per Unit Effort b. Fall Catch per Unit Effort u- '"- ~*
m %. .i
.........m w .i , :4
- - - . m im ,..
9 ,, _ lj ;1 9 u- t : a 8 ,, u in - : : :: -i y y T 8. / t o l !. ' N / I, E y u- .q- T s. B-i l\, l Y i'
.1 u 28
* . so - . *! \ j j{ -0
- - , i u- E y, g . 5
! ;i. Eg a .
Eh 6 .- n
-m x=
0.1 = U
*~ Omm Crab Csich
.......... Mrdrnum WunerTemp.
#8 i i i i 1 4 i i i i6 4 4 I I I I I i iI i iiiii G JA!4 E8 MAA Am MAY JUN JUL AUG SEP OCTNOV DEC 79 79 30 81 87 83 64 1304878419909 92 MONTH YEAR Figure 10-5. a. Mean monthly catch per unit effon log (x+1) and 95% confidence intervals for green erab (Carcinas maenas) collected during preoperational yean (1983-1989) and operational years (1991 and 1992) and b. Mean fall (October. December) catch per unit effort for green crab in Hampton-Scabrook Harbor and its n:lationship to minimum winter temperature from 1978-1992. Seabrook Operational Report,1992.
w 84000 - Bwh.de = i15 im - - iso
'. w im - \ - iu 0 p m- i /. .,' ..., - im g w ', ! '. .' S W m- '. / \ / ,'. - 7s 3w a \ : * :
~- -"
\. l \. E mm - .... .
.., -u iiiiiiie i i i i i e i i i i i ie i 71 73 73 74 73 76 77 74 79 80 ti 41 33 64 43 se #7 at 49 90 9 91 YEAR Figure 10-6. Number of clam licenses issued and the estimated bushels per acre of adult
(>50 mm) clams in Hampton.Seabrook estuary, 1971-1992. Seabrook Operational Repon,1992. 10-9 cu, , _
SOFT-SHELL CLAM (#YA ARMARIA) ; Recreational clam digging on the Hampton the B-type retroviruses is known to initi-Ilarbor flats had tieen a significant source ate the disease in Nya (0prandy et'al. of mortality for adult clams (>50 mm) 1981). Although the infection has been through 1988. The perturbation it caused observed in regions of relatively pristine was probably a source of mortality to waters, the rate of infection may also be smaller clams as well. Hampton Harbor enhanced by pollution-mediated deteriora-flats were closed to clam digging from tion of the environment (Reinisch et al. April 1989 through December 1992 by the 1984). The infection rate in some Nya New Hampshire Department of llealth and populations may reach 100 percent with 100 lluman Services due to coliform contamina- percent mortality of infected clams tion. With the Hampton Harbor flats (Farley et al. 1986). The incidence of closed, the pressure on the adult clam sarcomatous neoplasms in Hampton Harbor population was lifted, increasing the nya populations was observed in October estimated number of bushels per acre 1986 and February 1987 (Hillman 1986, dramatically (Figure 10-6). 1987). Neoplastic infections were more prevalent in February, reaching 6% at Flat Another anthropogenic influence on the 1 and 27% at Flat 2. Infections were Hampton Harbor clam population could be absent f rom Flat 4. Assuming 100 percent caused by clam seeding. In 1987 and 1988, mortality of infected clams (Farley et al. attempts by the New Hampshire Fish and 1986), Flats 1 and 2 may have suffered Game Department to augment natural re- subs tantia1 disease-related reductions in cruitment by seeding juvenile clams at clam production. In 1987, cle.m flat Flat 5 were not successful (Morris 1989), surveys indicated that juvenile and adult During the fall of 1988, the local 4-H densities fell by over 50% at Flat 1 and organization planted 30,000 seed (ap- Flat'2 while Flat 4 remained unchanged proximately 12 mm) clams on Flat 4 (47.9 from the p. evious year. In November 1989, acres), which can be converted to roughly fifteen large (>40 mm) clams were taken 0.01 clams /sq. f t. In late November,1989, from Flat 2, and 80% had neoplastic cells the 4-H again planted 100,000 seed clams (verified by D.J. Brousseau, Ph.D.; on Flat 4, or roughly 0.05/sq.ft., Fairfield University; Fairfield, CT). At although no population increase was Flat 4 during the 1990-1992 operational evident shortly after the planting period, adults >50 mm have nearly quadru-(R.Woj tusik, 4-H; UNH Cooperative Exten- pied their preoperational abundance in sion, Durham, NH; pern. comm. June 1992), comparison to other flats (Table 10-1), i The absence of neoplasia may contribute ; to these spatial differences. 10.3.5 Miect of Disease Sarcomatous neoplasia, a lethal form of 10.4 DISCUSSION cancer in Nya arenaria, has been identi-fled in a limited number of samples taken Since the Hampton-Seabrook estuary from Hampton Harbor Nya populations contains the majority of New Hampshire's (Hillman 1986, 1987). A virus similar to stock of the recreationally-important 10-10 1 i
SOFT-SHELL CLAM (NYA ARENARfA) 1
)
soft-shell clam, an extensive sampling the high densities that began in the mid-program has been undertaken in order to 1970s and ended in the early 1980s, characterize the natural variability in similar to trends noted in Maine and the population for all lifestages. Massachusetts (Crago 1993). As a result, densities of spat and juveniles from the Recruitment and survival of the soft- operational period (1990-92), even though shell clam population in Hampton Harbor similar to recent years, were lower than is af fected by a variety of factors, the preoperational average (Table 10-3, 2 including predation and disease, that must Figure 10-4) . The reasons for the recent be considered in impact assessment. mortality of young-of-the-year sets and Recruitment of larvae to young-of-the-year their decreased survival since 1984 are is not well understood, but is apparently complex, but certainly include the in-unrelated to the abundance levels of crease of its major predator, green crab larval stages (NAI 1982). Successful Carcinus maenas. Varm winter temperatures young-of-the-year sets have occurred from 1984 through 1989 may have enhanced throughout the preoperational period as green crab survival, coinciding with well as during 1990 (NAI 1992 and Figure decreased densities of spat and juvenile 10-4). Young-o f-the-year densities in clams. Lower green crab catches in 1990 1992 were less than the higher-than- corresponded to increases in spat and average levels observed in 1990, and below juvenile clams on some flats (NAI 1991). the 1974-1989 average. Considered In 1991 and 1992, when green crab catches together, young-of-the-year densities for were high, densities of spat and juvenile the operational period (1990-1992) were clams were below average (Figures 10-4, similar to the preoperational average at 10-Sb). Flat 1, and lower than average at Flats 2 and 4 (Table 10-3). In the nearfield/ Another factor in the evaluation of farfield comparison study of 1-12 mm long-term trends is human predation by clams, average densities during the clem diggers. The harvest of adult clams preoperational and operational periods md disturbance of the flats may have were not significantly different, although namp ared survival of juveniles as well. clams were significantly more abundant in The number of clam licenses sold dropped Plum Island Sound than in Hampton Harbor sharply beginning in 1981 with the reduced (Table 10-3). numbers of adults available to harvest. This was followed by closure of the flats Survival of the benthic stages of sof t- in 1989 due to co11 form contamination. shell clams depends on a number of factors The decrease in clamming resulted in an including the level of disease and pre- increase in the numbers of harvestable dation. The preoperational period in- clams throughout Hampton Harbor that was cludes the extremes of a " boom and bust" sustained through the mid-1980s. After cycle of spat, juvenile and adult clams, that time, low numbers of spat from in part dictated by a classic predator- offshore . sources and juveniles limited prey relationship. Densities averaged recruitment to the adult size class. In over the 1974-1989 period are elevated by 1992, the adult population at all three 10-11 1
-w
TABLE 10-3.
SUMMARY
OF EVALUATION OF EFFECTS OF OPERATION OF SEABROOK STATION ON SOFT-SHELL CLAM. SEABROOK OPERATIONAL REPORT, 1992. OPERATIONAL PERIOD SPATIAL DIFFERENCES SIMILAR TO PREOPERA- CONSISTE}frBETWEENOPERATIONgL STUDY LIFESTAGE TIONAL PERIOD
- AND PREOPERATIONAL PERIODS NEARFIELD/FARFIELD Larvae Yes Yes Young-of-year (1-12mm) Yes Yes HAMPTON HARBOR Young-of-year (1-5mm) No Flats 2, 4 Op< Preop Flat 1 Op= Preop r Spat (6-25mm) Op< Preop Yes
? Juvenile (26-50mm) Op< Preop Yes U Adult (>50c:m) No Flats 1, 2 Op= Preop Flat 4 Op> Preop
- Operational period for larvae = 1991, 1992; 1->50 m size classes = 1990, 1991, 1992; preoperational period for larvae = 1988, 1989; preoperational period for nearfield farfield = 1987-1989; preopera-tional period for Hampton Harbor = 1974-1989; results based on Op-Preop term of ANOVA model, when-Preop-Op x Area is not significant.
Desults based on interaction term (Preop-Op x Area) of ANOVA model and LS means multiple comparisons i at alpha = 0.05. 1- __ _ _ -_ _ . s. _ _ __ _ _ _ _ _ _ _ _ _ _ _ . __
SOFT-SHELL CLAM (#YA ARENARIA) Seabrook Nuclear Plant. Battelle study Seabrook area during the operation of no. N-0954-9901 to YAEC. 6 pp. Seabrook Station. Tech. Rep. XXIII-I. l . 1987. Final report on Oprandy, J.J. , P.W. Chang, A.D. Promovost, determination of neoplasia in soft-shell K.R. Cooper, R.S. Brown, and V.J. Yates, clams Nya arenarla near the Seabrook 1981. Isolation of a viral agent Nuclear Plant. Battelle study no. N- causing hematopoietic neoplasia in the 0954-9901 to YAEC. 7 pp, soft-shell clam, Nya arenarla. J. Invert. Pathol. 38:45-51. Norris, J. 1989. Results of clam ex-periment are clear as mud. Union Leader Ropes, J.W. 1969. The feeding habits of Sunday News. February 19, 1989:p3A. the green crab Carcinus moenas (L. ) U.S> Fish Wild 1. Serv. Fish. Bull. 67:183-Newell, C.R. , and H. Hidu. 1985. Species 203. profiles: life histories and environ-mental requirements of coastal fishes Reinisch, C.L., A.M. Charles, and A . M . and invertebrates (North Atlant!c) -- Stone. 1984. Epizootic neoplasia in sof tshell clam. U.S. Fish Wild 1. Serv. soft-shell clams collected from New Biol. Rep. 82(11.53). U.S. Army Corps Bedford Harbor. Hazardous Waste 1:73-of Engineers, TR EL-82-4. 17 pp. 81. Normandeau Associates , Inc. 1979. Soft- SAS Institute, Inc. 1985. SAS User's shell clam, Nya arenaria, study. Guide: Statistics, version 5 edition. Technical Report X-3. SAS Institute, Inc. , Cary, N.C. 956 pp. 1982. Seabrook Environmental Turner, H.J., Jr. 1949. The soft-shell Studies, 1981. Soft-shell clam, Nya clam industry of the east coast of the arenarla study. Technical Report XIII- United Stat (s. App. I. Report on II. investigations of the propagation of the soft-shell clam, Nya arenarla. WHOI 1985. Seabrook Environmental collected repI!nts 1948, Contribution j Studies, 1984. A characterization of No. 462, pp. IL-42. baseline conditions in the Hampton-Seabrook Area, 1975-1984. Technical Welch, W.R. 1969. Changes in abundance Report XVI-II, of the green crab, Carcinus renas (L.) in relation to recent temperature 1991. Seabrook Environmental changes. U.S. Fish Wild 1. Serv. l Studies. 1990 Data Report. Technical Fish. Bull. 67:337-345. l Report XXII-1.
. 1992. Seabrook Environmental Studies, 1991. A characterization of environmental conditions in the Hampton-10-14
[ SOFT-SHELL CIAH (#YA MMARTA) in adult densities in the 1990-1992 flats increased. Closure of the flats likely increased ' survival of the adult period. Flat 4 was also the only area size class. where historically no evidence of the' lethal disease neoplasia was detected s Another factor likely affecting growth Given the high variability among years,- - and survival of clams was the presence of and the complexity of factors affecting sarcomatous neoplasia, a lethal form of clam recruitment, there is no indication cancer in the soft-shell clam. During that Seabrook Station has had a positive 1986 and 1987, the incidence of neoplasia or negative ef fet.1. on the Hampton Harbor in Hampton Harbor was restricted to Flats population. 1 and 2 (Hillman 1986, 1987). Significant increases in adult clam densities in the 1990-1992 operational period in comparison "0.5
. LITERATURE CITED to previous years occurred primarily at Flat 4, where neoplasia was absent at that Ayer , V.C. 1968. Sof t-shell clam popu-time. Neoplasia has been suggested as a lation study in Hampton-Seabrook Harbor, cause for declining catches in New England New Hampshire. New Hampshire Fish and (Crago 1993). Game Dept. 39 pp.
The key to monitoring the effects of Coe, V.R. and H.J. Turner. 1938. plant operation (1990-1992) on the sof t- Development of the gonads and gametes of shell clam population is understanding its the soft shell calm #ya arenarla. J. long-term cycle and the multitude of f ac- Morph. 62:91-111. tors that affect it. Average seed clam J Crago, 1993. Getting to why. (1-12 mm) density during the operational T.I. period in Hampton Harbor followed the same Understanding leukeuia in sof t shell-trend as that of a neighboring estuary, cisms. Nor' easter 5(1):20-23. Indicating that Seabrook Station was not af f acting larval settlement (Table 10-3). Dow, R. 1972. Fluctuations in Gulf of : In Hampton Harbor, average spat and juve- Maine sea temperature and specific mol-nile densities f rom 1990-1992 at each flat luscan abundance. J. Cons. Int. Explor, were lower than the preoperational aver- Mer 34(3):532-534. i age. However, the 15-year preoperational period includes extremely successful peri- Farley, C.A., S.A. Otto, and C.L. ods of clam recruitment and survival, when Reinisch. 1986. New occurrence of densities of its major predator were low, epizootic sarcoma in Chesapeake Bay soft as well as periods of very low clam shell clams, Nya arenarla. Fish. Bull. , density, leading to significant differ- U.S. 84(4):851-857, ences in density among years. Average densities of adults during the operational Hillman, R.E. 1986. Summary report on period were similar to the preoperational determination of neoplasia in soft - average at Flats 1 and 2. Flat 4 was the shell clams, Nya arenarla, near the only area to show a significant increase 10-13
. . . ~ . . - .. . . . .. . .
North Atlantic April 22,1994 ENCI.OStrit0 2 TO NYN-94050 t 1994 HIGI.OGICAI,l'ROGitAM AND MODIFICATIONS 4 r# l l l l J
.)f
a
) -=
i Ortii CeW.7s03874 Teleonone (603)474 9521 l naa%E Ati[ antic Energy Service Corporation NYE. 93027 December 21,1943 Nlr. Edward K. NieSweeney Wastewater Nianagement Branch United States Environmental Protection Agency John F. Kenned) Building Boston, N1A 02203
References:
a) Seabrook Station NPDES Pennit No. NH0020338 b) North Atlantic letter NYE-93020 dated October 15,1993, " Technical Resiew Papers", R.J. Del.oach to E.K. NicSweeney
Subject:
1991 Biological Program and Ntodi0 cations Dear Nir. NicSweener As required under sections 1 A.I j (4), and I.A.ll of the Seabrook Station NPDES permit [ Reference (a)), North Atlantic Energy Service Corporation (North Atlantic) is providing the 1994 biological monitoring program (Enclosure 1). A meeting of the Technical Advisory Committee (TAC) on December 7,1993 at Seabrook Station was held to discuss the biological, hydrological and chlorine minimization programs. As part of the agenda, proposed modi 0 cations to the biological programs as presented in three technical papers (Reference (b)] were discussed and eva!uated by members of the FAC and North Atlantic. Following formal presentations of the technical papers, members of the TAC esaluated the materials and presented North Atlantic with their detennination of those items acceptable for modif,:ation at this time. The following is a summary of each request and the TAC detennination:
- 1) North Atlantic requested modi 0 cation to the current ichthyoplankton (fish eggs and larvae) monitoring program through the deletion of duplicate samples during each of the four monthly sampling periods (Enclosure 2). The current monitoring program collects four replicate samples (two held as a contingency) at three stations, during four monitoring periods per month. The proposed program would collect two replicate samples instead of four, processing one and holding one as a contingency. The request was developed through a statistical review of the preoperational and operational data that determined that no appreciable loss of sensitivity in the tests to detect operational impacts would occur. This recommendation was accepted by the i AC and will be incorporated within the 1994 monitoring program.
- 2) A request was made by North Atlantic to modify the existing surface exposure panel program. i The current program cellects short term exposure panels and monthly sequential exposure pancis 1 at two neardeld monitoring stations (Station 1119, B04) and two farfield control ctations (Stations B31 D34)(Enclosure 2). A request to reduce this effort by climinating duplicate nearueld and l 1
i l a member of the Northeast Utilities system
1 , 1 i l l United States Fnvironmental Protection Agency December 21,1991 Attention: Mr. Edward K. McSweeney page two I l 1 farlield stations as well as to modify the monitoring frequency was presented. Following their I review, the TAC accepted suspension of monitoring at the duplicate stations (Station B04,1134), howeser, the TAC requested that the short-term panel program be continued at the remaining ; stanons (D19, 831) for two years. In addition, new exposure panels will be added to each remaining station and collected on a quarterly basis. These new exposure panels will pro $ide aJditional information in advance of the short-tenn program reduction. The modifications will be incorporated within the 1994 monitoring program.
- 3) North Atlantic presented a request for the elimination of the phytoplankton program, as well as related nutrient analysis. Ph>toplankton communities are made up of diverse groups of species that are influenced by a multitude of physical, chemical, and biological factors some of which change on a seasonal basis while others change within a time span of days, hours, or minutes.
These parameters base been fbund not to be influenced by the operation of Seabrook Station. Other utilities have demonstrated this relationship and have not monitored phytoplankton since the early 1980's. The TAC reviewed this material and determined however, that phytoplankton and nutrient analysis at Seabrook Station should continue. As a result, this program will be continued within the 1994 monitoring program without change. Nonb Atlantic requests that EPA and the State of New Hampshire approve the 1994 biological monitoring program as amended by the TAC at the December 7,1993 meeting (Enclosure 1). It is North Atlantic's understanding that the TAC has determined that relative to future modifications, an operational pesiod of five years would be required to demonstrate operational impacts, should they occur, to the - biological communities being monitored. Following this period, it is understood that the TAC will work with North Atlantic to establish the long term " maintenance" monitoring program through program modifications based upon the receipt of additional data. Program modifications in the interim will be reviewed by the TAC and a' proved in those areas where the data clearly depicts a need for program changes. North Atlantic identitled at the December 7,1993 meeting, a number of items that should be considered for modification in the near future, it was suggested that a meeting to evaluate these issues be scheduled for the spring of 1994. Should you require additional information on the 1994 Biological Program or Modifications, please do not hesitate to contact either myself at (603) 474 9521, extension 2846 or Kenneth W. Dow, Site Environmental Engineer, at extension 2401. Very truly voors, b fr' Y R. Jeb DeLoach Executive Director - j Engineering and Licensing
-l RJD:RASlact I I
l Enclosures l l l l t
1 l 1 i United States Environmental Protection Agency December 21.1993 Attention: Mr. Edward K. McSweeney Page three ec: Dr. Edward Schmidt Department of Environmental Services Water Supply and Pollution Control , 6 flazen Drive Concord, NH 03302 Mr. Ted C. Feigenbaum Senior Vice President and Chief Nuclear Officer North Atlantic Energy Service Corporation o P.O. Box 300 Seabrook, Nil 03871 1 i j
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4 North Atlantic December 21.1993 ENCI.OSUllE I TO NVE-93027
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1994 SCHEDULE Amo SMPLE PERICOS FOR 810 LOGICAL SAMPLING + : : MONIN AND SAMPLlhG PERIGO :
- F!hf!SM : .
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- (sarpte/stn) : J : F : M : A : M : J : J : A : S : O : h - D . SAMPLES :
- OTTER TRAWLS (2) : : : : : : : . . : : : : .
- Stn T1, T2, T3 : ma : xx : mm : mm : xx : xx : mm : mm : an : xx : ax : an : 144 :
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- GILL EEis (2) : : : : : : : : : : : : : : .
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- SEluES (2) : : : : c : : : : : : : : : :
- Stn 51, 52, 53 : : : : x : a : x : a : m -
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- IMPikGCMEET : Weekly & ring Circulating Water System operation : : i
- Stn El : : :
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- MONTH Ako SAMPL thG PERICD :
- SENTHCS
- : : : : 1014L :
- : 0 : D : SAMPLES :
- (sample /stn) : J : F : M : A M : J : J . A S N .
- MAa!NE SENTMOS :
- Intertidal : : : : : : -
mon destructive (2) : : : : - a : : : : : a : 36 :
- Stn 1MSL, SMSL, 1MNW, : : : : : . : : : : -
- 5MwW, 1 MtW, 5 MLW : . . . . . . .
- Intertidal Transects (3): : .
- : : a : 18
- Stn 1Mit, SMSL : : : : a -
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- Stetidal Transects (6) : . . :
- 72 :
- Stn 19, 31,' 17, 35 : : : : m : : : m . .
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General Algae (1) : : : : : : : : : : . : -
- 1MLW, SMtW tidepools : : : : -
- 1Mst, SMSL tidepools : : : : : : : : : : . . : :
- : : x : : m : : : a : : 40
- 1MLW, 5MLW, UtSL, SMSL.: : : .
4, 13, 16, 17, : : : : : : : : - 19, 31, 34, 35 : : : : : : : : : : : : : :
- a : : : : : : : : :
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- : x : :
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- 1MLW,-SMLW, 4, 13, 16, : : : : : a : : : x :
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- ESTUAR!kE RENTieOS : : : : : : : : : .
- Destructives (5) : : : : : : :
Stn 3, 9 : : : : : x : : : x : : : m : : 60 : Stetidat, MLW : : : : : : : : : : . a = Stations 4, 13, to, 34 saspted annually (August only)
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4 1994 SCHEDULE AND SAMPLE PER1005 FOR SIOLOGICAL SAMPtikG
- : MONTH AND SAMPLIhG PERIOD :
- BENTMOS :
- : : : : : : : : : : : : : ICIAL :
- (smg>t e/stn) : J : F : M : A : M : J : J : A : S : O : N . D : SAMPLES -
- a : : : : : : . .
- SURFACE PAkELS : : : : : : : -
- Taxonury : : : . : : : : : : : -
- ST (30-day) (2) : : : : : : : -
- Stn 19, 31 : x : x : x : x : x : x : x : x : x : x . x . x : 48 :
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- MS (30-365 day) (1) : : : : . : : : -
- Stn 19, 31 . m : x : x : x : x : a : x : x x : x : x . xx . 26 :
- QT (90-360 day) (3) : : : : : : : : : : :
- Stn 19, 31 : : + x : : : x : -
- x : : . x -
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- a : : : : . : -
- BOTTCM PANELS .
- TA (120 DAT) (1) : : : . : : : : : . : . : : "
- Stn 4, 19, 31, 34 : : : : x : : : : x : : -
- x : 12 :
- LT (1 YEAR) (4) : : : : : : : . : : : :
- Stn 4,19, 31, 34 : : : : : : : : x . : .
- 16 :
- EP! BENTHIC CRUSTACEA : : : : : : : : : : : : . : [
- CREEN CRAB (2) : : : : : : : : : : : : . :
- Estuarine Flat 2 : : : : : : : : : : : : : :
- Stn 1, 2, 3, 4 : xx : : : xx : xx : xx - xx : xx : xx : xx : xx : xx : 160 .:
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- LOCSTER/ ROCK CRAB (1) : : :
- Discharge Stn L1 : 30 traps hauled 3 times / week (approx)
- Control Stn L7 : Jme - Novescer : 156 :
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- Short Tern MS = Monthty Sequential QT s Quarterly TA = Triennual (3x/Yr)
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i North Atlantic December 21,1993 J ENCLOSURE 2 TO NYE-93027 1 I s
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North Atlantic April 22,1994 ENCLOSIIRE 3 TO NYN-94050 OCEAN TEMPERATilllE COMPLIANCE PitOGRAM MODIFICATIONS o
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@ Seab o k NH 03874 g g Telephone (603)474 9521 Energy Service Corporation NYE- 93002 January 20, 1993 Mr. T. E. Landry Permit Compliance Section Environmental Pr'dection Agency John F. Kennedy Federal Building Boston, M A 02203 S ubject: Ocean Temperature Compliance Program Modification ,
Dear Mr. Landry:
Enclosed please find a white paper entitled, " Optimizing Seabrook Station's NPDES Ocean Temperature Compliance Program." At the December 11, 1992, Seabrook Station Environmental Studies meeting, North Atlantic discussed plans with the Technical Advisory Committee to modify the plant's cooling water discharge temperature compliance program in 1993. The attached paper further details the information discussed at the meeting. The paper includes an analysis of two years of operational temperature monitoring data and demon'strates that discharge temperature compliance can be fully achieved with two temperature monitoring stations instead of the three existing stations, implementation of this program modification will yield a substantial savings associated with equipment maintenance and data acquisition from the monitoring station without significant effect on the quality of operational temperature monitoring. North Atlantic Energy Service Corporation requests your authorization to implement this modification in the near future. Should you have any questions regarding this matter, please contact Mr. James M. Peschel, Regulatory Compliance Manager, at (603) 474-9521, extension 3772. Very truly yours, b*h R. J. DeLoach Executive Director - Engineering and Licensing RJ D: ALL/act fin clos u r e ,
-l cc: Mr. Ted C. Feigenbaum Senior Vice President and Chief Nuclear Officer .
North Atlantic Energy Service Corporation P.O. Box 300 ; Seabrook, NH 03874 l l a member of the Northeast Utilities system l
1 l North Atlantic-January 20, 1993 l l l 4
,l ENCLOSURE TO NYE 93002 i
OPTIMIZING SEABROOK STATION'S NPDES OCEAN TEMPERATURE COMPLIANCE PROGRAM 5 l 1 l l 1
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l OPTIMIZING SEABROOK STATION'S NPDES. OCEAN TEMPERATURE COMPLIANCE PROGRAM i
1.0 INTRODUCTION
1.1 Purnose -) This report presents ocean temperature data that demonstrate how federal / state discharge I permit compliance in the receiving waters from the thermal component of the Seabrook Station t Circulating Cooling Water System can be maintained with two monitoring stations. l L 1.2 Backeround Seabrook Station is a single-unit,1,150 megawatt nuclear generating facility located in the New Harnpshire coastal town of Seabrook. The heat dissipation system for the station is a once-through, ocean intake and submerged diffuser discharge design. Cooling water is taken _ from and returned to the waters of the Atlantic Ocean via 19-foot diameter intake and discharge tunnels that extend about 7,000 and 5,500 feet offshore, respectively. The National Pollutant Discharge Elimination System (NPDES) permit sets thermal discharge limits during station operation [1]. Specifically, the thermal component of the discharge shall not increase the temperature of the receiving waters by more than 5 F, exceps in the near-field jet-mixing region where the 5'F limit applies only at the surface. The jet-mixing region la defined to be water within 300 feet of the submerged diffuser in the direction of discharge. Lastly, the permit is very clear in that the thermal discharge limits apply only to temperature rises caused oy the addition of heat to the receiving waters. This temperature difference, or delta-t, is the key to demonstrate permit compliance. 1.3 Comoliance Demonstration The analysis of a two-year baseline study of the thermal field around the discharge area , prior to station operation showed that permit compliance can effectively be defined by using the monthly mean of three thermal monitoring stations [2]. The stations include areas both inside j
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and outside the jet-mixing region as well as a reference point. Stations DS, ID, and T7 on Figure 1.1, respectively, correspond to these areas. Table 1.1 lists the location of each station and the various monitoring depths. The U.S. Environmental Protection Agency and New Hampshire Department of Environmental Services, Water Supply and Pollution Control Division, concurred that compliance is demonstrated if the delta-t value between reference Station T7 and those at DS and ID is 5'F or less for the monthly mean [3,4]. 1.4 Summary Two years of station operational data demonstrate permit compliance. The delta t value for all monitoring stations fer each month was less than 5 F. The largest delta-t values occur inside the thermal jet-mixing region during the winter months when the station is at 100% l power. The delta-t values outside the jet-mixing region, on the other hand, are small and do not
, vary significantly, regardless of the season or station power level, This occurs throughout the water column and indicates that there is little or no influence by the thermal discharge plume outside the jet-mixing region.
Therefore, since permit compliance is demonstrated inside the jet-mixing region, it will-be demonstrated outside the region as well. Compliance can, therefore, be achieved by using-the surface temperature monitor at Stations T7, maintaining the existing surface temperature monitor at Station DS, and by eliminating Station ID entirely. J 2
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TABLE 1.1 l l Seabrook Temocrature Monitorine Information ! l I l Water Depth Sensor Depth i Station (Ft, MLW) Location Designation (Ft, MLW) l l T7 55 42*55'15"N T7UP -2, Surface Following i 70 46'46"W T7MD -28, Surface Following l T7LO -53, MLW l i ID 57 42 54'00"N IDUP -2, Surface Following 70*47'15"W IDMD -28, Surface Following I IDLO -53, MLW DS 54 42 53'41"N DSUP -2, Surface Following 70*47' 12"W l l i l 1 I 1 l
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i -2.0 ANALYSIS
- 2.1 Station and Instrument Ooeration Seabrook Station received its operating license in March 1990, with full-power operation starting in August 1990. Power operation continued until late July 1991, when a scheduled
, two-month outage took place. Power operation resumed in October 1991 and continued through early September 1992, when the second scheduled outage took place. These operational periods are referred to as Cycle 1 and Cycle 2, respectively. The average monthly percent of station operation, which accounts for short-term power outages, is listed in Table 2.1 and illustrated in Figure 2.1. Ocean temperature data were obtained from sensors at the three monitoring stations via
- satellite telemetry during each month of station operation. Data recovery during Cycles 1 and 2 was about 90%. Missing data resulted from instrument malfunction.
2.2 Previous Data and Conclusions The results for 1990 and 1991 data, presented in two reports [5, 6], made the following ) conclusions:
- 1. The delta-t values for all monitoring stations for each of station operation month .1 were less than 5 F. Permit compliance, therefore, was demonstrated.
i
- 2. The largest delta-t values occur inside the thermal discharge jet-mixing region.
- 3. The delta-t values in the jet-mixing region vary with station power level and season. The maximum delta-t value occurs at 100% station power in the winter months during isothermal ocean conditions. The minimum delta-t value occurs in the summer months during strong thermally stratified ocean conditions.
- 4. The delta t values outside the jet-mixing region are small and do not vary significantly, regardless of station power level or the season. This occurs throughout the water column and indicates that there is little or no influence by _
the thermal discharge plume. Thermal plume verification studies [7] confirm this. 2.3 Cvele 1 and 2 Approach Cycle 1 and 2 data were developed to review the two factors that affect delta-t values, power level and season. For the power level effect, monthly average delta-t values were calculated only on days when the station was at 100% power level. For the seasonal effect, the-delta-t values at 100% power level were reviewed for isothermal conditions only, judged to occur during October through April. The 100% power, isothermal condition will produce the worst-case result, that'is, the largest delta-t value. I i i i i
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y + r .c TABLE 2.1 g Station Power Level. Percent of Oncration i. . Power Level Month , 1990 1991 1992 JAN - 100.0 100.0 , FEB - 71,0 100.0 MAR - 91.4' 100.0 APR - 75.2 100.0 MAY - 100.0 100.0 JUN - 74.9 100.0 JUL 74.1 65.8 100.0 AUG 80.8 , 100.0 SEP 94.4 * ** OCT 83.4 70.0 NOV 42.0 100.0 DEC 100.0 96.0 Outage, End of Cycle 1
- j. Outage, End of Cycle 2 1
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