during 1983-85 as measured volumes of jellyfish 

 were lowest in 1985 when Stage 2 larval abundance 

 was the highest. In addition, laboratory studies 

 had shown that a larva which contacted a tentacle 

 was stunned and ultimately died, even if not con- 

 sumed. Jellyfish abundance in 1986 was similar 

 to 1983 and that in 1987 was similar to 1985, but 

 the numbers of Stage 2 larvae at station A in 

 1986 and 1987 were both low compared to 1985 

 (Fig. 20). However, this does not discount the 



potential of jellyfish predation. Abundance of 

 Stage 2 larvae in 1987 was low at all stations and 

 this possibly obscured observations on the effects 

 of predation. Although the predator-prey rela- 

 tionship of jellyfish on winter flounder larvae in 

 the Niantic River was not as clear as once thought 

 (NUSrO 1987), the fewer older larvae (Stages 3 

 and 4) in the upper portion of the river may have 

 been related to jellyfish predation. 



40 



30 



20 



10 



1984 



15FEB 01 MAR 15MAR 29MAR 12APR 26APR 10MAY 24MAY 



DATE 



Fig. 20. Weekly mean volume (liters per 500 m ) of Cyanea sp. medusae collected at station A in the Niantic 

 River from 1983 through 1987. 



Entrainment of larvae at MNPS 



The number of winter flounder larvae entrained 

 by MNPS was related to larval densities in Niantic 

 Bay and plant operations. Generally, larvae were 

 entrained from late February through June with 

 most entrainment occurring from mid-April 

 through May. The median larval densities from 

 entrainment collections in 1986 and 1987 were 

 some of the lowest since 1976, but the estimated 



numbers entrained were among the highest due 

 to the start-up of Unit 3 (Table 13). Although 

 Unit 3 did not start producing commercial power 

 until April 23, 1986, condenser cooling- water 

 pumps in operation varied throughout the occur- 

 rence of winter flounder larvae in Niantic Bay 

 during 1986. The percentages of each develop- 

 mental stage respectively entrained in 1986 and 

 1987 were similar, with Stage 1 representing 2% 

 in both years; Stage 2, 21% and 29%, Stage 3, 



Winter Flounder Studies 



183 



