The black sea 



Table 165 



417 



6 to 10 g (at a depth of 15 m). During its spring bloom the amount of phyto- 

 plankton increases as one moves from the open sea to the coast, bays and 

 inlets (according to Morozova-Wodjanitzkaja (1948), 250 to 300 times). Thus, 

 in July 1938, 25 miles away from the Crimean shore there were, at a depth of 

 to 25 m, on the average 1 1,000 cells per litre, and in the Bay of Sevastopol 

 37,000; the respective data for October were 17,000 and 107,000. During the 

 spring bloom up to 31 million cells per litre were recorded in the Bay of 

 Sevastopol. 



Phytoplankton density decreases with depth, but it is still high at a depth 

 of 100 m ; in depths below 50 m phytoplankton cells probably sink down and 

 phytosynthesis is no longer possible. 



Whereas in its open parts the Black Sea is considerably inferior to the Sea 

 of Azov as regards its quantity of phytoplankton, in its bays and inlets the 

 amount of phytoplankton approximates to that of the Sea of Azov. 



A comparison of the quantitative data on the Black Sea phytoplankton 

 with those of different areas of the Atlantic Ocean (the off-shore zones) leads 

 Morozova-Wodjanitzkaja to the conclusion that 'as regards its quantitative 

 phytoplankton development the Black Sea is not inferior to the North Sea . . . 

 or the Atlantic Ocean near the North American coast. ... In the Antarctic the 

 amount of phytoplankton (number of cells) is ten times higher than in the 

 open parts of the Black Sea, but it is much lower than that of its bays and inlets.' 



S. Maljatzky (1940) gives the quantitative data on the average content of 

 phytoplankton in the photosynthetic zone (a 75 m layer of water) in the open 

 parts of the northeastern half of the Sea. At the beginning of the summer 

 (Fig. 200a) phytoplankton is particularly abundant in the part of the Sea 

 adjacent to the Kerch Strait and in the circumlittoral zone south of Novoros- 

 siysk : in the second half of the summer high indices of phytoplankton bio- 

 mass were found also in the central parts of the Sea (Fig. 200b). In the first 

 case the biomass in some areas was more than 200 mg/m 3 ; in the second 

 more than 400 mg/m 3 : i.e. it was found to be close to the phytoplankton bio- 

 mass of the Central Caspian. 



S. Maljatzky (1940) and N. Morozova-Wodjanitzkaja have given a descrip- 

 tion of the phytoplankton of the eastern half of the Sea. The phytoplankton 

 of the western half of the Black Sea and of the northwestern area was com- 

 prehensively studied by P. Usachev (1928) and G. Pitzik (1950, 1954). 



Both investigators have recorded high productivity indices for this area 

 of the Sea. The number of phytoplankton in the Odessa area reaches 5 milliard 



2D 



