ascertain the cause of the relatively low resistance to plankton 

 organisms in this part of the Bering Sea to these toxic 

 contaminants. 



Comparing the data obtained in the Bering and Chukchi 

 Seas in 1988 and similar experiments performed in the Baltic 

 Sea in 1987, it should be noted that the ranges of critical 

 concentrations of the investigated pollutants were very similar 

 (Tables 7,8) (Liftshits & Korsak, 1988; Korsak & 

 Timoshenkova, 1990). It is evident that the resistance of the 

 plankton community of the Baltic Sea to BaP and PCB's was 

 lower than in the Bering Sea (Korsak & Timoshenkova, 1990; 

 Liftshits & Korsak, 1988). On the other hand, the resistance of 

 plankton of the Bering and Chukchi Seas to Cu and Cd was 

 much lower than that in the Baltic Sea (Liftshits & Korsak, 

 1988; Korsak & Timoshenkova, 1990). These differences are 

 probably very significant because the temperature of the 

 Bering/Chukchi Sea water was 10°C lower than during the 

 research in the Baltic Sea. 



As a result of these investigations, it should be noted that 

 from the number of pollutants under consideration, the most 

 dangerous pollutants to the plankton communities of the Bering, 

 Baltic, and Chukchi Seas are BaP and Cu, because the maximum 

 concentrations of these pollutants in the water are nearly the 

 same values as the critical concentrations. The other pollutants 

 investigated appear less hazardous to the plankton communities. 



10 20 



Fig. 8. Variations of some functional characteristics (p,BP.P/Bp) in 

 ecotoxicalogica! experiments. 



TABLE 1 



The toxic effects of PCB's and BaP to primary production in ecotoxicological experiments 

 (relative values of primary production represented in %). 



361 



