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



Table 11 



East 

 Total No. Barents White Kara Laptev Siberian Chukotsk 

 Family of species Sea Sea Sea Sea Sea Sea 



Qualitatively rich fauna, in a series of groups almost as varied as Barents 

 Sea fauna, is found only at the northern boundary of the Siberian seas at the 

 edges of the continental shelf, washed at the depth of some hundreds of metres 

 by the warm intermediate layer of Atlantic water, and in the deep trenches 

 entering the Kara and Laptev Seas from the north. 



The richest benthos as regards numbers is found in the southeastern, 

 shallower part of the Barents Sea, in its central shallows and on the southern 

 and eastern slopes of the Spitsbergen shallows. The southwestern half of the 

 Barents Sea has quantitatively the richest plankton. A sharp decrease of the 

 biomass and an impoverishment of the qualitative composition of benthos 

 and plankton can be observed as one moves into the northern part of the 

 Barents Sea and eastward beyond Novaya Zemlya. 



The southeastern part of the Kara Sea, the Laptev and East Siberian Seas 

 are probably the poorest in benthos and plankton, and the biomass of plank- 

 ton and benthos increases again only in the eastern part of the Chukotsk Sea. 



The high salinity and the strong vertical circulation of the Barents and 

 Chukotsk Seas ensure richness of pelagic and bottom life. In the seas situated 

 between Novaya Zemlya and Wrangel Island the aeration of the bottom 

 layer and of the whole water column is, at any rate in certain seasons of the 

 year, impeded by the considerable desalting of the surface layer ; this has an 

 adverse effect on the development of life. The latter perhaps suffers even 

 more from the extremely severe climatic conditions of these seas, which are 

 only free from their ice cover for a short period, from the almost complete 

 suspension of the growth of phytoplankton for ten months of the year, and 

 finally from the considerable lowering of salinity in the southern part of the 

 whole chain of Siberian epicontinental water bodies. Their productivity must 

 be many times lower than that of the Barents Sea. Since the biomass in these 

 seas in summer, when it is flowering, is three to five times, or perhaps even 

 eight to ten times smaller than that of the Barents Sea, its annual production 

 must be much less. 



The process of growth can serve as an indicator of the comparatively slow 

 rate of the biological processes in the northern seas as compared to those 

 taking place in the southern ones. Thus, for example, the fouling process in 



