410 BIOLOGY OF THE SEAS OF THE U.S.S.R. 



3 4 5 6 



2000 



100 

 I 



50 



50 



_1_ 



100 



J 



mg/m- 



Fig. 194. Distribution of micro-organism population and its density in the water 

 column of the Black Sea (Kriss, 1958). 



scheme for the horizontal circulation of the upper layer of water, determining 

 equally the position of the lower limit of oxygen and the upper limit of 

 hydrogen sulphide. 



Black Sea micro-organisms and their quantitative distribution. In his mono- 

 graph A. Kriss (1958) gives some data on the total number and the biomass of 

 the Black Sea bacteria population, determined by the method of membrane 

 ultra-filters (Figs. 194 and 195).* The number of micro-organisms decreases 

 from one or two hundred thousand specimens per 1 ml of water to a few tens 



