INTRODUCTION 



Power plant entrainment of planktonic organisms is of ecological 

 concern due to the large volume of water used for condenser cooling. 

 Organisms entrained are subjected to a rapid increase in temperature, 

 mechanical stress, and at times the presence of biocides. Plankton 

 studies have been conducted at Millstone Nuclear Power Station since 

 1970. The objective of these studies is to provide information on the 

 distribution and seasonal abundances of plankton in the waters around 

 Millstone Point, and in the cooling water of the Millstone Nuclear Power 

 Station. This information is necessary to understand the general ecology 

 of the local plankton populations, and assess the potential impact of 

 the power plant. Plankton studies have examined phytoplankton, zooplankton 

 and ichthyoplankton. 



This report summarizes plankton studies conducted at Millstone and 

 evaluates the need of the present and future studies relative to Units 1 

 and 2 and the startup of Unit 3. 



PHYTOPLANKTON 



Phytoplankton are an essential component of the marine ecosystem 

 since they are primary producers. The loss of phytoplankton due to 

 entrainment was of concern because of the potential loss of energy 

 assimilation capacity at the base of the food chain. Various special 

 studies to assess the impact of entrainment and a monitoring program 

 have been conducted from 1970 to 1982. 



Woods Hole Oceanographic Institution conducted several phytoplankton 

 studies at Millstone Unit 1 from September 1970 through June 1972 



