5-41 



composition of a community (Osman, 1977) . Osman found substantial 

 differences in community structure which were dependent upon the time of 

 initial settlement, length of exposure, size of panel, and nature of 

 disturbance. In New Jersey, yearly cycles in settlement were reported 

 to be similar from year to year, but species composition was annually 

 variable (Hoagland, 1977) . There does, however, seem to be a fairly 

 stable New Haven Harbor panel assemblage that bears some similarity to 

 Millstone (1977) and undergoes periodic additions and deletions. Domi- 

 nant members of this assemblage include: Corophium insidiosum, Polydora 

 ligni, Balanus eburneus , B. improvisus , Obelia longissima. Teredo nava- 

 lis, and Mytilus edulis. 



ANALYSIS OF IMPACTS OF NEW HAVEN HARBOR STATION OPERATION 



The possible impact of New Haven Harbor Station operation on 

 the benthic community as studied by exposure panels would be related to 

 operation of the condenser-cooling system. The condensers receive 

 ambient temperature water and discharge heated effluent at 15 °F above 

 ambient (NAI, 1976b). The thermal plume (dating from operation start-up 

 29 August 1975) intersects the surface at a temperature of 4°F above 

 ambient and occupies an area less than 0.1% of the inner harbor. The 3, 

 2 and 1°F isotherms bound 0.4, 0.6 and 1.0 percent of the inner harbor 

 area, respectively (Section 3-2 this report) . A special survey revealed 

 that the thermal plume from the station could occasionally intersect 

 Stations 8 and 9 with a 0.9 - 1.8°F (0.5 - 1°C) temperature increase 

 (NAI, 1977) . The New Haven Harbor Station fouling panel array (B) is 

 adjacent to Station 9 (Figure 5-1) . 



Entrainment in the condenser cooling water and exposure to 

 increased water temperatures from the thermal plume are the major modes 

 of impact associated with power-station operation. As discussed in the 

 introduction, entrainment may reduce numbers of recrui table larvae to 

 the fouling panel community. Depending on their magnitude, increased 

 water temperatures have a range of potential impacts upon the community/ 



