13-S 



Impact 



As evidenced by chlorophyll a values, phytoplankton blooms 

 have not been reduced but have progressively increased in magnitude 

 during the post-operational years (1975 through 1977) . Due to natural 

 variability in phytoplankton standing stock and its dependence on many 

 factors, it is difficult to isolate causes of long-term changes in 

 production levels; such assessment is particularly difficult in nutri- 

 ent-enriched areas (such as New Haven Harbor) where standing stock 

 varies considerably among years (Flemer and Sherk, 1977) . 



i 



Differences observed in zooplankton assemblages were assessed 

 by evaluating whether operational data fell within the ranges esta- 

 blished by preoperational monitoring. With the change in sampling 

 methodologies, these comparisons were made qualitatively, based on a 

 conversion between methods, and indicated that no substantial or impor- 

 tant change in zooplankton density or distribution patterns can be 

 attributed to New Haven Harbor Station operation. 



Dominant taxonomic groups of ichthyoplankton collected in New 

 Haven Harbor were similar from year to year. Observed seasons of peak 

 occurrence, dominant taxa and species represented among the ichthyo- 

 plankton in New Haven Harbor all closely resembled comparable data 

 collected and reported by previous investigators of Long Island Sound 

 ichthyofauna. Year-to-year fluctuations in total ichthyoplankton abun- 

 dance, as well as abundance of selected taxa, are comparable to the 

 natural variability seen in studies conducted in Long Island Sound and 

 vicinity between 1943 and 1968. 



Overall, New Haven Harbor plankton assemblages observed sub- 

 sequent to operation of New Haven Harbor Station are indistinguishable, 

 qualitatively and quantitatively, from those observed prior to power 

 plant operation. A notable exception was a general increase in phyto- 

 plankton standing crop. It is beyond the scope of this investigation to 

 determine specific causes, but the increase may be related to such influ- 



