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



the ratio of the production of micro-organisms to their biomass is 127-7 for 

 the Caspian Sea. 



The number of micro-organisms in the bottom-soil of the Northern part 

 of the Caspian Sea reaches, according to A. Zhukova (1955), 12 milliards of 

 cells per one gramme of wet soil, in the Southern and Central parts 128 to 

 897 millions, and in the inlets, according to D. Evdokimov (1937), 105-7 to 

 1,627-6 millions per one gramme of wet soil. 



A. Kriss (1958) considers that the total biomass of the micro-organisms 

 in the Caspian Sea is probably as much as 1,600,000 tons. 



Plankton 



Qualitative composition of phytoplankton. P. Usachev's comprehensive work 

 (1941) and I. Makarova's data (1957) on the diatoms are used by us for Cas- 

 pian Sea phytoplankton. The general composition of the plankton algae by 

 groups is given in Table 241. 



Blue-green algae constitute half the dominant and characteristic forms and 

 diatoms about 34 per cent. Thus, contrary to other seas, blue-green algae 

 acquire a predominant significance, while the Peridineae occupy third or 

 fourth place {Table 242). 



Table 242 



