100 



50 



Station 3 



10 

 Copper Concentrations (pg/1) 



20 



2 4 10 



Copper Concentrations. (|ig/ll 



4 10 



Copper Concentrations (|jg/l) 



20 



100 



50 



10 

 Copper Concentrations (|jg/l) 



Station 89 



20 



4 10 



Copper Concentrations (|jg/l) 



20 



Fig. 1 . Negative effects of Cu concentrations on primary production (P) and 

 the total number of infusoria (N) on Stations 3. 7, and 9. 



100 



Station 110 



10 

 Copper Concentrations Ipg/I) 



20 



Fig. 2. Negative effects of Cu concentrations on pnmary production (P) and 

 the total number of infusoria (N) on Stations 45, 89, and 1 10. 



BaP additions were located in the Bering Sea on Station 3, and 

 microzooplanlcton on Stations 7 and 9 (Tables 1,5; Figs. 6.7). 

 It should be noted that toxicity tolerance of BaP increased from 

 Station 3 to Station 7 (from 0.1 to 10 ^g/l, Figs. 6,7; Table 1 ) 

 when primary production is used as a biological target. 



A toxicity tolerance of the bacterioplankton community to 

 BaP was higher than for phytoplankton and the bacterial 

 production rates in ecotoxicological experiments were much 

 larger than in control bottles (Tables 1,5). This stimulation 

 effect can probably be explained by the influence of released 

 organic matter from dead plankton organisms. The data of 

 primary and bacterial production obtained in ecotoxicological 

 experiments can be used to calculate P/D coefficient changes 

 under different additions of pollutants (Table 5; Fig. 8). The 

 P/Bp coefficients were calculated and found to be in good 

 correlation with P/D coefficients, which we believe depend 

 upon the stability of the whole plankton community (Odum, 

 1975; Izrael & Tsyban, 1989). The critical concentration of 

 BaP to the plankton community ( target P/Bp) was calculated to 



be about 0.05 |ig/l (Table 8). It should be mentioned that the 

 critical concentrations of BaP to the phytoplankton and 

 microzooplankton population were the same order but higher 

 than for the whole plankton community (Table 8). 



The critical concentration values of Cu (2-20 |ig/l) to 

 phytoplankton had the same order of variation as BaP (Tables 

 1 ,2,7). The Bering Sea microzooplankton were found to have 

 critical concentrations of Cu. about 2-15 |ig/l (Table 7; 

 Figs. 1 ,2 ). The average critical concentrations of Cu for phyto- 

 and microzooplankton in the Bering Sea were, correspondingly, 

 10 and 6 |ig/l (Table 7). The phytoplankton populations most 

 sensitive to Cu additions were located on Stations 3 and 89. and 

 for microzooplankton, correspondingly, on Stations 7 and 9 

 (Figs. 1.2). 



It is necessary to mention that bacterial production increased 

 in ecotoxicological experiments on Stations 3 and 4 with larger 

 Cu concentrations, but in other areas on Stations 7 and 35, the 

 values of bacterial production decreased significantly 

 (Table 4). The critical concentration of Cu (target bacterial 



358 



