The production of bacterioplankton in warm surface waters of 

 eutrophic regions averages 0.2-2 g/m-^ per day (according to the data of 

 the radiocarbon method). The duration of 1 generation (doubling time of 

 the number of bacteria) is 15-40 h. The mean daily P/B coefficient is 

 0.5-1. The generation time and P/B coefficients of bacterioplankton as 

 a whole depend less on the trophic level of the basin than on the 

 temperature of the water (Sorokin, 1971a, 1973b, 1974; Karapetyan, 

 1971). 



In the upper layer of the water of mesotrophic regions--waters in 

 the temperate zone, the neritic zone of the tropical and subtropical 

 regions--the total number of bacteria is 0.3-1.5'10" cl/ml, biomass 

 0.05-0.5 g/m-^ (Table 5). Production (based on the results of 

 measurement by the radiocarbon method) in open waters in the summer 

 averages 0.1-0.3, in the neritic zone--0.3-l g/rtr per day. The P/B 

 coefficient of bacterioplankton is usually 0.3-0.6. 



In oligotrophic surface waters--the trade wind currents in the 

 oceans and eddy regions--the total number of bacteria decreases to 50- 

 150-103 cl/ml, the biomass--5-50 mg/m^ (Sorokin, 1964, 1971a, 1973c; 

 Novozhilova et al . , 1970; Strickland, 1971; Hobbie et al . , 1972). 

 Production is usually 5-30 mg/m-^ per day, the P/B coefficient is high-- 

 1-2. 



In stratified oceanic basins, there are several maxima of 

 concentration of bacterioplankton: in the surface film, over the 

 thermocline and in the upper boundary of the intermediate Antarctic 

 waters. In these layers, the biomass and production of bacterioplankton 

 are usually several times higher than the average values we have 

 presented (Sorokin, 1971a, c, 1974) (Fig. 13). 



In cross sections from the shore into the ocean, the biomass and 

 production of bacterioplankton in the surface layer both decrease 

 rapidly (Fig. 14). The enriching influence of the shelf off small 

 islands stops at a distance of only a few miles from the shore (Sorokin, 

 1973b). In the water deeper than the euphotic zone, the population, 

 biomass and production of bacteria decrease rapidly with depth. 

 Excluding the layer of the maximum at the upper boundary of the 

 intermediate Antarctic waters at a depth of 450-550 m, the mean values 

 of total population of bacteria deeper than 200 m drop to 2-6 • 10-^ cl/ml, 

 of biomass to 0.2-0.8 mg/m-^, 10-20 times less than at the surface. The 

 production of bacteria in the deep and intermediate waters decreases 

 still more— by a factor of 50-100, to 0.01-0.05 mg/m^ per day. In the 

 layer of the maximum, at a depth of about 500 m, these quantities are 5- 

 10 times higher (Sorokin, 1971a, c, 1973c, 1974). 



These values of number and biomass of bacterioplankton were 

 obtained by the method of direct microscopy. Measurement of the wet 

 biomass of bacteria in the deep waters by the ATP method yields 2 to 5 

 times higher values (Holm-Hansen, 1969; Lyutsarev et al . , 1975). The 

 reasons for the difference should be sought, apparently, in the fact 

 that these values of biomass are at the boundary of sensitivity of the 

 ATP method and cannot be determined by this method with sufficient 

 reliability. Also, the ATP method yields the actual biomass of all 



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