6- 

 4- 



a 



C ■ 



LJ 



Z) 4- 



t— 



< 



LU 

 Q. 



1000 meters 



500 meters 



Ld 



100 meters 



L2- 



Ld 



< e- 



h- 



^ 



AM /% Af) >^ 



\J 



M 



V 



hhtiC 



y 



H ^ 



A 



y 



TIME IN DAYS 



Fig. 14. Seawaler temperatures on the bottom (5-1 1 m) at 100, 500 and 1000 m during 3-unit operation at 

 the Millstone Nuclear Power Station. Temperature data from 100 m were collected from March 3 to March 

 12, 1988, while those from 500 and 1000 m were collected from March 16 to March 25, 1988. 



from its designated site during the May-Oct 1986 

 exposure period. Based on mformation collected 

 during 2-unit operation, this was the distance/ 

 period most likely to support a population of the 

 non-native shipworm; in November 1985, we 

 identified 14 T. bartschi in panels at 100 m. 

 Therefore, the relative distribution of T. bartschi 

 at 100 m during 3-unit operation will not be 

 known until the October 1987 pemels are pro- 

 cessed. However, it is known that under 3-unit 

 operating conditions, they have not extended their 



distribution to 500 or 1000 tn, even though T. 

 navalis settlement was high. 



The continued trend of decreasing T. navalis 

 abundance with increasing distance from the 

 quarry appears to be a response to an environ- 

 mental gradient. Among the possible variables 

 are water depth, water flow, and water temperature 

 (surface and bottom). Such a gradient would not 

 have to persist year-round, as long as it existed 

 during the period of shipworm settlement (June 

 through October). 



Exposure Panel Program 



249 



