7-22 



The New Haven Harbor Station condenser-cooling water system 

 takes in ambient temperature water and discharges effluent at 15 °F above 

 ambient (NAI, 197Gb). Maximiim plume temperature is reduced to 4°F above 

 ambient at the surface in the immediate area of discharge (Section 3.0). 

 No intertidal areas are directly impinged by the thermal effluent, 

 according to isotherms plotted from infrared overflight data and temp- 

 erature and dye studies (Section 3.0). It is possible that the East 

 Shore transect could be minimally impinged under special wind and tide 

 conditions, as it falls within the area of hydrographic Stations 8 and 9 

 which could be affected by a 0.9 to 1.8°P (0.5 to l.OC) increase (Section 

 3.0). However, planktonic larvae that are vital to maintenance and 

 repopulation of intertidal areas might be moved some distance by the 

 plume momentum or they might be stressed by contact with the pl\ime, in 

 either case altering settlement. Furthermore, the entrainment of eggs 

 or pelagic larvae of intertidal community members could result in mor- 

 tality or sublethal effects. 



Indirect effects which thermal effluents may have on inter- 

 tidal populations are numerous. Due to effluent discharge currents, 

 changes may occur in circulation which promote erosion or increased 

 sedimentation of an intertidal area. Food sources may be depleted if 

 plankton abundance, a primary component in the diet of intertidal 

 filter feeders, is reduced by entrainment; conversely, food could become 

 more available as detritus due to entrainment mortality. Changes in 

 predatory pressure may result from shifts in distribution and behavior 

 of predators due to increased local temperatures. In New Haven Harbor, 

 which already receives a variety of industrial and municipal wastes, 

 heated effluents might encourage synergistic effects and therefore 

 increase the toxicity of pollutants (Nay lor, 1965) . Preoperational dis- 

 solved oxygen concentrations in the harbor have been dociamented to be 

 extremely low in the summer. This is unrelated to station operation and 

 probably represents natural summer conditions of low dissolved oxygen 

 solubility (Section 3.0). Thus n\amerous mechanisms exist which could 

 affect the intertidal faunal composition of New Haven Harbor. These 

 effects, whether positive or negative, could be manifested in sudden 



