the tidal Interchange between Long Island and Block Island Sounds totals 

 8.6% of the entire volume of Long Island Sound below mean low water 

 (Bumpus et al . 1973). It is unlikely, therefore, that detectable 

 changes in zooplankton species composition or abundance will occur 

 during 3 unit operation. 



SUMMARY 



1.) The composition and abundance of MNPS zooplankton in 1983 was 

 examined and was comparable to previous years. 



2.) The Copepods V7cre the dominant group, contributing approximately 

 90% to MNPS zooplankton in 1983. Dominant species in this group 

 were A. hudsonica , A. tonsa, C^. hamatus , P^. minutus , and T, 

 longicornis . Other dominant taxonomic groups included Cirripedia 

 (nauplii and cyprids of B. balanoides and B. improvisus ) , 

 Gastropoda (eggs and vcligers of L. littoria ) , Decapoda (zoea and 

 megalopa of Brachyura) , Cladocera ( Evadne spp. and Pod o n spp.), and 

 Amphipoda (Gammaridea) . 



3.) Distinct winter-spring and summer fall zooplankton communities were 

 identified at MNPS and were similar to zooplankton communities in 

 LIS nnd BIS. Harmonic regression models and the mean annual 

 residuals; were developed for A. hudsonica , A. tonsa , C^. hamatus , P^. 

 minutus , T^. longicornis , cirripedian nauplii and cyprids, and 

 brachyuran zoea. These models indicated recurring annual patterns 

 in abundance for these taxa. 



4.) Inshore (F,N) , offshore (NB) and diel differences in zooplankton 



densities were observed, and were attributed to natural variation. 



3.) Changes observed in the Millstone zooplankton community over the 

 past twelve years are within those observed in other areas of LIS 

 and BIS. As a result, we conclude that any effect of the Millstone 

 Nuclear Power Station on the zooplankton community in the vicinity 

 of the power plant was negligible. 



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