THE CASPIAN SEA 



603 



animals changed places, the mysids occupying the first place (54 to 98 per 

 cent), while the Limnocalanus biomass went down to 4-2 to 22-7 per cent. 



The Central Caspian zooplankton biomass is subject to both seasonal 

 and annual fluctuations. The data for the spring of 1938 and 1939 showed an 

 increase of zooplankton biomass in 1939 (the average biomass for 1938 was 287 



Fig. 285b. Distribution of zooplankton biomass of 

 Central and Southern Caspian in May 1939 (Idelson). 



mg/m 3 , for 1939 — 362 mg/m 3 ) while its qualitative composition remained 

 unchanged (Fig. 285b). The same fact was recorded for phytoplankton. In 

 autumn 1938 the zooplankton biomass was higher (86-2 mg/m 3 ) than in the 

 autumn of 1934 (55 mg/m 3 ). There are no similar observations for the 

 Southern Caspian. Similar indices were, however, obtained for this part of 

 the Sea in 1938 and 1939. Plankton biomass data from different parts of the 

 Sea (Jashnov) are given in Table 250 for the autumn of 1934; Rhizosolenia, 

 however, is not included. 



