4-73 



inshore areas of Long Island Sound over a 30-year period. Fish-egg 

 densities were generally low except during June and July when Anchoa 

 spp. and Labrids predominated. Urophycis/Enchelyopus/Peprilus eggs were 

 most abundant during April and May. Total fish eggs and Anchoa spp. 

 eggs were most abundant at Stations 18 and 20 (1975, 1976) and 8, 11, 

 and 18 (1977). Labrid eggs were generally most abundant at Station 20. 

 Urophycis/Enchelyopus/Peprilus eggs were most ab\indant at Stations 8 

 (1975, 1977) and 20 (1976) . Fish larvae were most abundant during July 

 and August, reflecting the appearance of Anchoa spp. larvae. Larvae of 

 Cynoscion regalis , an important sportfish, were also most abundant 

 during July, while lairvae of Pseudopleuronectes americanus, a major 

 commercial and recreational fish, were most abundant during April and 

 May. Total fish larvae were most abundant at Stations 20, 11 and 3. 

 Anchoa sp(p). larvae showed little evidence of spatial heterogeneity 

 throughout the survey period. C. regalis larvae did show evidence of 

 spatial heterogeneity but the pattern was difficult to interpret. P. 

 americanus larvae were most abundant at Stations 8, 20 and 11 with 

 Station 8, located in proximity to the New Haven Harbor Station, under- 

 going the greatest relative increases in annual abundance between 1975 

 and 1977. 



ANALYSIS OF IMPACTS 



There are two principal means by which the plankton community 

 may be directly impacted by the operation of New Haven Harbor Station : 

 1) by being drawn through the power plant's cooling system, (entrainment) 

 and 2) by being exposed to the heated discharge as it diffuses and mixes 

 with the receiving water. In the case of power-plant passage, both 

 temperature and mechanical injury appear to be instr\imental in causing 

 mortality; temperature alone is responsible for the detrimental effects 

 of plume entrainment. Other potential causes of death include stresses 

 associated with abrupt increases and decreases in hydraulic pressure 

 (e.g., formation of gas emboli in body fluids) as organisms pass through 

 various parts of the cooling system, and contact with biocides and other 



