GENERAL CHARACTERISTICS OF THE NORTHERN SEAS 43 



Phyto-plankton 



Winter Spring Summer. Winter 



уткет г о Autumn 



Summer ШИШ Autumn 



Fig. 5. Biological seasons of plankton. A General indices 

 (Bogorov). В Phyto-plankton development (Usachev). 1 Cir- 

 cumpolar part of Arctic Ocean, 2 Central region Of Kara Sea, 

 3 Laptev Sea, 4 Northern part of Barents Sea, 5 Southwestern 

 part of Barents Sea. 



Zooplankton 



According to V. Bogorov's estimate, the zooplankton of our northern seas 

 on the basis of existing data includes 321 species* of which 41 species are 



* It must be borne in mind that the populations of separate seas and parts of them 

 have not been studied equally well, as regards the qualitative variety of the fauna and 

 flora. The Kara Sea plankton is probably as varied as that of the Barents Sea, but the 

 former has been the subject of a more comprehensive survey. 



