4.1.1 Total Number, Biomass, and Activity of 

 Bacterioplankton 



ALLA V. TSYBAN, VASSILIY M. KUDRYATSEV, VLADIMIR O. MAMAEV, and NADEZHDA V. SUKHANOVA 



Institute of Global Climate ami Ecology. State Committee for Hydrometeorology and Academy of Sciences, Moscow. USSR 



Introduction 



Until recently, marine microbiologists investigated only 

 general characteristics of heterotrophic microorganisms. 

 However, the development of new techniques (to measure 

 biomass, growth rates, and metabolic activity) (Vieble, 1984), 

 coupled with oceanographic measurements, has made it possible 

 to quantitatively assess the importance of microorganisms in 

 cycling of various organic and inorganic chemicals in the 

 ocean. Such methods are now applied to detennine ecotoxicity 

 and resident times of different anthropogenic contaminants. 



Investigation of microbiocenoses and quantitative 

 assessment of microbiological processes in marine environment 

 are the most important elements in the evaluation of 

 anthropogenic inputs on marine ecosystem and their assimilation 

 capacities. Information on the assimilation capacity can be 

 obtained from long-term studies conducted across different 

 geographical zones of the World Ocean (Izrael & Tsyban, 

 1983, 1989). 



Long-term microbiological research in the subarctic and 

 arctic seas was started in the eariy 1980"s. Eariy results 

 (Tsyban et al. 1987b; Izrael et al.. 1988) showed that the 

 growth and function of microbiocenoses depended on the 

 hydrological and hydrochemical conditions of the sea. The 

 increase in human population and factors, and the transport of 

 anthropogenic contaminants into the sea. has appreciably 

 affected the growth and activity of marine microflora (Izrael & 

 Tsyban, 1981, 1983a,b; Korsak, 1985). 



Materials and Methods 



Microbiological studies in the Bering and Chukchi Seas 

 were conducted by the Soviet-American ecological expedition 

 in summer 1988 (see Frontispiece). These studies paid particular 

 attention to specific regions in these seas. In the Bering Sea, 

 research efforts focused on the eastern and southern areas of the 

 deep Bering Sea, the relatively shallow regions of the central 

 area and the Gulf of Anadyr, and the shallow shelf area m the 

 Chirikov basin. All these regions have unique hydrological, 

 chemical, and biological conditions. 



To assess total population and biomass of bacteria, 381 

 samples were assayed in the BeringSea, of which 320 samples 

 were assessed for dark CO, assimilation by bacteria. 



Microbiological studies were conducted for the first time 

 in the Chukchi Sea. The study focused on the southern ice-free 

 area of the sea to assess total number and biomass of bacteria; 

 1 1 5 samples were taken. For dark CO, assimilation by bacteria, 

 107 samples were taken at 21 stations. 



Total number of bacteria was determined directly on 

 membrane filters "Synpor" with pore diameter of 0.32 |im 

 (Razumov, 1932). A volume of 10 to 20 ml of water was 

 filtered, cells stained with 5% erythrosine, and counted by light 

 microscopy. Counts were done on 10-20 visual fields with a 

 total magnification of xI.OOO. The number of bacteria was 

 calculated by the formula: 



X: 



Sx lO^xa. 

 S, X b xc 



where 



The biovolume of bacterial mass was estimated from the 

 average volume and total number of bacteria: 



where 



V 

 n 



v, 



V = n X v, 



biovolume of bacterial mass, ^m'; 

 number of bacteria per liter of water; 

 average volume of a single bacterial 

 cell, ;Um\ 



The linear dimensions of single bacterial cells were 

 determined (Tsyban et al., 1988) with a calibrated eyepiece 

 micrometer. From such measurements, the average volume of 

 bacterial cells was calculated and equaled to 0.30 ;^m- . 



Bacterial mass was determined (Sorokin & Kadota, 1972; 

 Romanenko & Kusznetsov, 1974) by the formula: 



Ph= nx vx 15x 10'' 



2x 100 



55 



