The distribution of nutrients ot the East Polygon was 

 typical of such a shelf-slope region. In the surface layers the 

 nutrients concentration was found to be low and their 

 concentration increased slowly below 100 m. 



The microbiological community was characterized by 

 variability ofwater mass in the East Polygon. The development 

 of the heterotrophic, saprophytic microflora proved to be lower 

 in total numbers in the deepwater stations 1 and 3 at the depth 

 of 500 m (the indicator fonns were completely absent). There 

 were upper and lower layers where the number of saprophytic 

 bacteria varied from cells/ml to 10' cells/ml. 



Preliminary data indicated that microbial community 

 structure on the East Polygon did not change in comparison 

 with the 1984 results. The highest quantity and biomass of 

 neuston organisms was found on the East Polygon (in 

 comparison with the other investigated areas). The average 

 biomass was found to be four times higher than those results 

 reported in 1984. 



Very interesting experiments were undertaken for the first 

 time in the northern regions of the Bering (Gulf of Anadyr) and 

 Chukchi Seas. The ecosystems of the northern areas of the sea 

 are some of the most productive in the World Ocean. Results 

 of primary production showed values more than 12 g C/m-d '. 

 High concentrations of nutrients in the water masses are 

 responsible for the high primary production. Significantly, the 

 water mass is enriched with nutrients transported from the Gulf 

 of Anadyr through the Chirikov basin and the Bering Strait to 

 the southern area of the Chukchi Sea. This constant tlow fuels 

 the increase of phytoplankton numbers and production occurs 

 at the boundaries of these water masses. 



During the expedition, three local areas that had high 

 phytoplankton production were discovered along the axis of 

 the current. At these areas, the increase in biogenic sedimentation 

 was also observed with the particulate matter settling from the 

 euphotic zone containing more than 1.5% biogenic carbon. 



The lowest temperature (-1.6°C) was discovered in the 

 Gulfof Anadyr. Such low temperatures have not been observed 

 here during the last 20 years. In spite of the low temperatures, 

 significant phytoplankton biomass was found in the Gulf of 

 Anadyr. The highest values of chlorophyll « in the gulf reached 

 55 mg/nr\ The only values that were higher were those found 

 in the Chukchi Sea. 



In the coastal area of the Gulf of Anadyr, a high quantity 

 and biomass of microzooplankton and benthos were observed. 

 Biomass of benthic organisms reached !.()()() g/nr in several 

 investigated stations. The ecosystems in the Chirikov basin 

 depend greatly on the Anadyr Current, which carries into the 

 gulf different amounts of nutrients that are necessary for thte 

 growth of phytoplankton. In turn, large amounts of nutrients 

 were carried from the Chirikov basin through the Bering Strait 

 to the Chukchi Sea. 



The southern area of the Chukchi Sea, bemg intluenced by 

 Bering Sea waters, was rich in nutrients and unstudied until 

 this time. Also, new practical knowledge of oceanographic 

 features such as mass circulation, temperature, salinity 

 distribution, and the general structural and functional 

 characteristics of the ecitsystems was dclcrniined. 



During the expedition, we noticed that the function of the 

 ecosystems of the Chukchi Sea was determined by at least two 

 currents. High-salinity, nutrient-enriched, water masses are 

 transported from south to north. They are carried by a flow that 

 exits from the Gulf of Anadyr, crosses the Chirikov basin, 

 flows through the Bering Strait, and ends in the Chukchi Sea. 

 There is one more current, formed from the cold and relatively 

 high salinity coastal Siberian waters, that is also enriched with 

 nutrients. This current flows from northwest to southeast. 

 These two flows of nutrients, discovered in the Chukchi Sea, 

 determine the high biological productivity of this ecosystem. 

 The merging of these two currents formed a wide area in the 

 southeastern part of the sea. This area is characterized by the 

 following: 1. concentrations of chlorophyll a reaches 77 mg/m' 

 (a phytoplankton bloom was noticed at Station 45); 2. the 

 average number of neuston organisms was 

 4,000 specimens/m-; 3. the number of infusoria of the Chukchi 

 Sea was much larger than in the Bering Sea; 4. a maximum 

 number of mesozooplankton was in the larvae of benthic 

 organisms, which was dominated in the metazooplankton; and 

 5. high average biomass of benthic organisms — about 

 900 g/m- — was found, reaching 1,500 g/m- and even 

 2.000 g/m- at some individual stations. 



New species, which were not known before in the Chukchi 

 Sea (testaceous moUusks, some echinodermata, and others) 

 were found during the expedition. Many birds and mammals 

 were also observed. 



From various investigations, the data indicate that the 

 biological productivity is high in the Bering Sea and higher still 

 in the Chukchi Sea. In spite of the fact that the investigated 

 regions are far away from industrial areas, an array of 

 anthropogenic organic contaminants ( polychlorinated biphenyls 

 (PCB"s). hexachlorocyclohexane, chlordane. and DDT) were 

 found in the surt'ace waters of these seas. The average measured 

 concentration of hexachlorocyclohexane in the surface waters 

 of both seas was more than 10 times the values of other 

 anthropogenic contaminants (2.5 ng/1 isomer and 1.2 ng/1 

 isomer). Such levels of toxicants in the Bering and Chukchi 

 Seas are potentially hazardous for the vulnerable arctic 

 ecosystems. Analysis of the atmospheric samples produced 

 similar results: concentrations of benzene hexachloride 

 averaged 0.25 ng/m' and that for the isomer. 0. 12 ng/m'. 



The process of the degradation of the PCB's by natural 

 microbial populations of the Bering and Chukchi Seas was 

 studied. The preliminary results indicated that during the 

 exposure (21 days) at temperate 6-10°C, the microorganisms 

 oxidized up to 18% dichlorobiphenyl, up to 6% 

 trichlorobiphenyl, 1% tetrachlorobiphenyl, and <1% 

 penta/n-hexachlorobiphenyl (as compared to total amounts of 

 these compounds compared in industrial mixtures of PCB ). It 

 is important to note that the toxic compound 

 2, 3, 6, 2', 3', 6'-hexachlorobiphenyl was degraded by 50-70% 

 by various bacterial populations for 2 1 days. Altogether these 

 facts indicated thai a considerable part of chlorinated 

 hydrocarbons may be retained and may accumulate in this 

 arctic environment. This cau,ses serious concern as these 

 pol I Litanls ha\ e known negative effects on biological processes. 



VI 



