TABLE 3 



Structural and functional characteristics of the plankton 

 community of the Bering Sea in July 1984. 



reached the average value equal to 30 kcal/m- day, which made 

 it possible to classify the waters of the studied area as 

 hypertrophic waters. 



The degree of satisfaction of the food requirements of 

 consumers (8) was maximum, which was indicative of the 

 absolute availability of food. Ninety-four percent of their total 

 ration consisted of phytoplankton; the detrital component was 

 practically absent [E(i)/C(z)|. The average value of the index 

 (p), through which the role of detritus in the total volume of 

 energy assimilated by heterotrophs, was estimated and 

 accounted for only 11%. Consequently, the food chain of the 

 plankton community was realized more completely in the 

 waters of the Anadyr Current as compared to other studied 

 areas. 



In the waters of the central shelf region (the southern part 

 of the North Polygon) the level of the overall biomass of the 

 plankton community [B(o)l was very low and did not exceed 

 30 kcal/m'. This value was two times less than that in the waters 

 of the Anadyr Current. 



While the fraction of phytoplankton remained constant in 

 spite of the absolute reduction of the biomass of autotrophs by 

 half, the mesozooplankton content decreased by 10%, and its 

 biomass became three times less, and the role of bacterio- and 

 microzooplankton increased to 9% and 6%, respectively. 



The productivity of waters in the region underconsideration 

 was low and corresponded to the mesotrophic level. 



The relation between the rates of the primary production and 

 overall heterotrophic destruction pointed to the predominance 

 of the process of destruction of organic matter over 

 photosynthesis in the same proportion as in the deep-water 

 southwestern region of the sea. A deficiency of the consumed 

 organic autochthonous matter [P(o)] reached 5.3 kcal/m- day. 

 but it was covered in plenty at the expensive of allochthonous 

 organic matter [P(act)]. Judging by the low production rate of 

 phytoplankton (P/B = 0.25/day), the cells of algae were in an 

 inactive state. It is felt that the major fraction of phytoplankton 

 biomass arrived to this region from the water area of the Anadyr 

 Current where plankton was characterized by the maximum 

 possible production and by accumulation of the autotrophs due 

 to the horizontal mixing of water mass. 



Due to the low productivity of the shelf waters, the trophic 

 relations inside the plankton community were tense. The 

 degree of satisfaction of the nutritional requirements of 

 zooplankton did not reach the maximum level, 98-99%. Apart 

 from phytoplankton ( 78% ), bacterioplankton (14%) and detritus 

 made up the ration of the animals. The energy flux through the 

 detrital chain increased up to 30% (p) as compared to that 

 calculated for the Anadyr Current. In spite of the low 

 productivity of shelf waters, the rate of actual production 

 (^) of all the elements of the community was positive, 

 which pointed to a tendency towards an increase in their 

 biomass. 



205 



