matter destruction in euphotic zone averaged 8.4 |ig C/l/d, and 

 26.9 )ig C/l/d, respectively. Lower rates occurred in the Gulf 

 of Anadyr. 



Maximum activity of microflora and high rates of bacterial 

 production of 25.5 and 18.7 |ag C/l/d and organic matter 

 destruction of 8 1 .9 and 60.0 |.ig C/l/d were found at Stations 7 

 and26(Fig. I; Subchapter4. 2.1, this volume). The lowest rates 

 of bacterial production of 4.2 and 2.8 |ig C/l/d and organic 

 matter destruction of 13.4 and 9.1 |ig C/l/d were found at 

 Station 6 in the deep central part of the Bering Sea, and at 

 Station 1 1 in the Gulf of Anadyr. These results are similar to 

 those obtained for stratified waters in the vicinity of frontal 

 zone of the Irish Sea (Turley & Lochte, 1985). 



The results showed that the highest rates of bacterial 

 production and organic matter destruction occurred in the 

 surface microlayer and near-bottom waters in the deep central 

 basin of the Bering Sea, higher than rates measured in the zone 

 of phytoplankton photosynthesis. In Gulf of Anadyr, rates 

 gradually decreased with depth, and in bottom waters, rates of 

 bacterial production and organic matter destruction were two 

 times lower than in the surface microlayer. 



In general, the central part of the Bering Sea and Gulf of 

 Anadyr were characterized by the low bacterioplankton activity, 

 the low rates of bacterial production and organic matter 

 destruction, as well as by low production/biomass coefficient. 



Because of its distinct hydrological and hydrochemical 

 characteristics, the northern part of the Bering Sea is much 

 different in other areas in the sea. Shallow depths, intensive 

 water exchange and unstratified water column produced a 

 uniform distribution ofbacterioplankton and microflora activity. 

 The rates of bacterial production and organic matterdestruction 

 were high (Table 1 ) in this part of the sea. The average daily 

 rate was about 18|igC/l. Organic matterdestruction amounted 

 to about 56.6 |ig C/1, which is about 3 times higher than in the 

 Gulf of Anadyr. Integrated over the water column, the rate of 

 bacterial production was 0.8 g C/m- and destruction of 

 2.5 g C/m-. 



The highest microflora activities and diurnal rates of 

 bacterial production of 12.1 |ag C/l/d or 0.85 g C/m- were found 

 at Station 96 and the lowest rates at Station 92. The rate of 

 organic matter destruction at Station 96 was 68.0 |ig C/l/d or 

 2.7 g C/m-, whereas at Station 92 destruction was two times 

 lower (Fig. 2; Subchapter 4.2.1, this volume). 



The distribution of microflora activity in the Chirikov 

 basin was independent of the uniform distribution of 

 bacterioplankton. The rates of bacterial production and organic 

 matter destruction in the surface microlayer decreased with 

 depth. The daily rate averaged about 20 fig C/1 of bacterial 

 biomass in the surface microlayer while organic matter 

 destruction averaged to 65. 1 |ig C/l/d. 



Thus, the shallow waters of the northern Bering Sea was 

 characterized by high rates of bacterial production and organic 

 matter destruction, the integrated rates being much lower than 

 in deep water areas of the sea. In addition, microflora activity 

 varied horizontally and vertically, and P/B coefficient averaged 

 0.97 in the northern Bering Sea. 



Bacterial r— i Decomposition 



production H of organic master 



0.5g C/m 2 ■-I per l.Og C/nT 



• Station number 



CHUKCHI 



PENINSULA 



I ^'°° n 



M I. 104 



Fig. 2, Bacterial production and decomposition of organic matter in the 0.5 

 to 45 m layer in the northern Bering Sea, summer 1988. 



In summary, this investigation of microbiological processes 

 in the Bering Sea allowed us to assess the scales of some links 

 in production and transformation of organic matter. It was 

 shown that CO, assimilation by heterotrophic microorganisms 

 contributes to the production of organic carbon in the system. 

 Microflora contribution to the total production via CO, fixation 

 is sufficiently high and can amount to about 30% of the primary 

 production. In addition, microflora contributes to the destruction 

 of organic matter. The rate of destruction processes was 

 determined based on the activity of bacterial population, trophic 

 ability level, and hydrological and chemical conditions in the 



Bacterial Production and Organic Matter Destruction in the 

 Chukchi Sea 



The rates of bacterial production and organic matter 

 destruction were measured in the Chukchi Sea for the first time. 

 The results (Table 2) show that a relatively high rate of 

 production and destruction occurs in the water column. The 

 average rate of bacterial production was about 20 \ig C/l/d, or 

 0.8 g C/m-. The rate of organic matter destruction was about 

 64.9 ng C/l/d, or 2.5 g C/m-. These rates are slightly higher than 

 those in the Bering Sea. They agree with the rates of production 

 and respiration in mesotrophic waters, such as temperate seas, 

 regions of equatorial divergence, upwelling areas where daily 

 production of bacterioplankton biomass varied from 5 to 

 20 |ig C/1 and respiration from 10 to 60.0 |ig C/1 (Sorokin, 

 1985). 



Based on microflora activity, rates of bacterial production, 

 organic matter destruction, and bacterial respiration, some 

 areas in the sea differed from other areas. The highest microflora 



77 



