8-37 



t-i'^e, embryonic, and larval developmental stages (Kinne, 1970). Spawning 

 in many marine organisms is stimulated by the attainment of a certain 

 minimal water temperature (Davis, 1972; Mitchell, 1974; Wilson and Seed, 

 1974; Crawford and Homsher, 1975; Kinne, 1970). Above-normal seasonal 

 temperatures can result in spawning at inappropriate times with a res\ It- 

 ing decrease in larval survival success. Embryonic de^'elopment is 

 inhibited above a certain species-specific critical temperature (Davis, 

 1972; Kinne, 1970; Talmage and Coutant, 1978). This inhibition can lead 

 to prolonged planktonic existence, and consequently a longer exposure of 

 the organism to intensive predation with a resulting decrease in the 

 probability of survival. In New Haven Harbor, the influence of elevated 

 water temperatures on reproduction and embryonic and larval development 

 is not considered of major significance to the viability of the adult 

 populations, since the extent of the thermal impact area is limited (At 

 > 1°F detectable over a maximiom of 42% of the inner harbor surface. 

 Section 3.0) and because the harbor does not appear to be a major 

 spawning ground for most of the epibenthic invertebrates present. This 

 second position is supported by the relatively low densities of larval 

 epibenthic invertebrates collected annually in plankton tows (Section 

 4.0). The decapod crustaceans — including C. septemspinosa , C. irrora- 

 tus , 0. ocellatus , and H. americanus — comprise the most numerous group 

 of invertebrates collected in bottom trawls; yet comparatively low 



larval densities of this group have been observed in the plankton 



3 

 (yearly average of 4.5 to 23.3 larvae/m /month) (Section 4.0). This and 



evidence indicating that some invertebrates such as C septemspinosa and 



C. irroratus migrate from the harbor prior to the egg-hatching period, 



suggest that Long Island Sound supplies the major source of juveniles 



for most epibenthic invertebrate populations in the harbor. Recruitment 



to the adult population of larvae from the harbor is believed to be 



small in comparison to the contribution to the harbor of juvenile 



animals from Long Island Sound. 



Artificially elevated temperatures associated with a power 

 plant discharge can also influence adult distribution with a resulting 

 change in community structure (Kinne, 1970; Logan and Maurer, 1975; 



