418 



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



cells per 1 m 3 (G. Pitzik, 1950), and in the Bay of Sevastopol 30 milliard 

 cells (up to 12 g/m 3 : N. Morozova-Wodjanitzkaja, 1940, 1948). These data 

 are commensurable with those for the Sea of Azov. In the open part of the 

 Black Sea, in summer, the amount of phytoplankton is estimated as 5-10-15 

 million cells per 1 m 3 , and its biomass in tens of mg/m 3 ; however, it is many 

 times less than in the bays and inlets and in the shallows of the Sea, and hun- 

 dreds of thousands of times less than in the Sea of Azov, although in some 

 places in the open sea and in some samplings the amount of phytoplankton 

 was of the order of hundreds of milligrammes and even up to 1 ,700 g/m 3 . 



Fig. 200. Distribution of phytoplankton biomass (in mg/m 3 ) in the Black Sea 

 (Maljatzky, 1940). A 21 May to 5 June 1939; В 2 to 7 August 1939. 



Phytoplankton biomass throughout the Black Sea was estimated by 

 G. Pitzik : (1954) in a number of years as about 2-8 to 6-2 million tons. N. Moro- 

 zova-Wodjanitzkaja (1957) has tried to compute some general indices of Black 

 Sea plankton productivity. She thought that the daily production of phyto- 

 plankton in the open part of the Sea was 9-5 g in autumn and winter, and at the 

 beginning of the summer about 11-3 g under 1 m 2 of surface. The daily P/B 

 ratio (the ratio of the daily gain of production to biomass) was 1-7 in 

 February, 2-2 in June and 1-2 in September. Moreover, she has determined the 

 daily coefficient (the ratio of daily consumption to the original biomass, 

 CjB) as 1-2 to 1-7, and the daily coefficient (ratio of production to consump- 

 tion, Р/С) in the spring and early summer as 1 to 1-2, i.e. at that time of the 

 year consumption is completely compensated for by new growth (production). 

 By the end of the summer and in the autumn (September to November) this 

 last coefficient is equal to 0-9, i.e. consumption exceeds new growth. 



Quantitative distribution of zooplankton in the open parts of the Sea. Nikitin 

 (1945) has given a general picture of the quantitative distribution of plankton 



