THE SEA OF AZOV 



493 



direction, but in 1952, when the Tsimlyansk reservoir was filled, the salinity 

 of the Gulf waters rose again and ' marine ' fauna again moved eastwards. 

 There were no marked changes in the zooplankton biomass during 1950-52 

 (A. Novoshilova, 1955). A clear illustration of this process of changes in 



I 3 5 7 9 П S %„ 



5 7 9 I I 1 3 S %o 



9 S°/ c< 



Г 

 О 1 00. 



7 9 II 13 S% 



Fig. 235. Relation between the quantitative development of the main zooplankton 

 species and the salinity of the waters (Yablonskaya, 1957). A Fresh-water Rotifera 

 {Brachionus annularis, Keratella cochlearis, Keratella quadrata, Polyarthra trigld); 

 В Synchaeta sp. (a spring form) ; С Asplanchna phodonta ; D Calanipeda aquae dulcis ; 

 E Acartia clausi; F Heterocope caspia; G Acanthocy clops vemalis; H Fresh- water 

 Cladocera (Daphnia longispina, Diaphanozoma brachyurum, Laptodora kindtii); 

 I Mysidacea (1 Macropsis slabbed; 2 Mesomysis kowalevskyi). 



numbers with a change of salinity, as related to the Rotifera and Crustacea, 

 is given (Fig. 235) by Yablonskaya, who has also drawn a prognosis of 

 the distribution of the main zooplankton biocoenoses in the Sea of Azov 

 at different stages of the loss of river water due to irrigation measures 

 (Fig. 236). 



