/ \ '* 

 / \ '-* 



20JAN e9FEB 01 MAR 2 1 MAR I QAPR 3eAPR 20MAY e9JUN 

 DATE 



Figure 16. Weekly mean volume (liters per 500 m^) 

 of lion's mane jellyfish collecLed in 

 the Niantic River during 1983. 



causal predator-prey relationship was established, the increase in 

 medusae at stations A and B was coincident with a decline in larvae at 

 these stations (Fig. 9). Arai and Hay (1982) reported that several 

 species of hydromedusae were present and preyed upon Pacific herring 

 larvae when the latter were most abundant. Pearcy (1962) stated that 

 Sarsi a tubulosa medusae were important predators of winter flounder 

 larvae in the Mystic River and had greatest impact on the less motile 

 younger individuals. Over 40% of the Cyanea sp. medusae from the 

 Niantic River examined during a 1982 study (Dr. R. Brewer, Trinity 

 College, Hartford, CT, personal communication) contained unidentified 

 fish larvae in their gastrovascular cavity during mid-April, a time when 

 winter flounder larvae were abundant. If medusae were a significant 

 predator on larval winter flounder, the successive temporal decline in 

 larval abundance from the upper to the lower river could have been 

 partly due to predation. Since the larval dispersion model (Saila 1976) 

 showed the retention of many larvae in the upper arm of the Niantic 

 River, a potentially high predation by medusae may have occurred which 

 was not accounted for in the model. 



43 



