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densities and species composition were consistent with those reported at 

 Millstone Point (Battelle, 1977, 1978) and greater Long Island Sound 

 (Deevey, 1952a, 1952b, 1956). 



In New Haven Harbor, year-to-year fluctuations occurred in 

 total ichthyoplankton abundance, as well as abundance of selected taxa, 

 but were not indicative of impact, judging from the natural variability 

 as seen in studies conducted in Long Island Sound and vicinity between 

 1943 and 1968. For some taxa (e.g., Anchoa mitchilli) , numerical den- 

 sities during periods of peak abundance increased, comparing the years 

 1974 and 1975 with 1976 and 1977. The number of taxa represented was 

 lowest during the abbreviated 1974 program and was somewhat greater in 

 years having expanded sampling programs. Dominant taxonomic groups were 

 similar from year to year. Observed seasons of peak occurrence, domi- 

 nant taxa, and species represented among the ichthyoplankton in New 

 Haven Harbor all closely resembled comparable data collected and 

 reported by previous investigators of Long Island Sound ichthyofauna. 



Few spatial differences were detected in any of the plankton 

 studies (NAI, 1978a; 1977a; 1976a; 1975a; 1974a; 1974b; 1973). All dif- 

 ferences between stations were attributable to salinity, light and depth 

 gradients and were independent of Harbor Station operations. 



The overall conclusion is that plankton assemblages of New 

 Haven Harbor which have existed subsequent to operation of New Haven 

 Harbor Station are largely indistinguishable, qualitatively and quan- 

 titatively, from assemblages that existed prior to power plant oper- 

 ation. A notable exception to this generalization involves increases in 

 phytoplankton standing crop. Though these increases may reasonably be 

 attributable to influences such as improved water quality and expanded 

 treatment of municipal waste discharges, monitoring data offers no means 

 of evaluating this possibility. 



