THE KARA SEA 



231 



has been suggested by Hessle (1924) for the Baltic Sea, by the poisonous pro- 

 perties of manganese. 



As has been pointed out by T. Gorshkova (1957), the percentage of organic 

 carbon in the upper layer of the Kara Sea floor is comparatively small, vary- 

 ing between 0-27 and 1-99. 



None of these three reasons explains the fact that some animal forms thrive 



Fig. 98. Temperature cross section along the Kara Sea from the Karskie Vorota 



towards NNE to 81° N latitude in mid-September 1946 (Zenkevitch and Filatova). 



The thickness of the brown mud layer is given below in cm. 



on brown mud, notably all echinoderms (especially the brittle stars, asterids 

 and holothurians) ; some coelenterata (Metridium, Umbellula); some mol- 

 luscs (Pecten) and crustaceans (Mesidothea, Sclerocrangon). 



Lack of oxygen and high concentration of carbon dioxide are specially 

 marked in the deep-water layer of the Ob-Yenisey region, where the difference 

 in the salinity of the surface and deep-water layers is considerable (P. Lobza, 

 1945). 



IV. FLORA AND FAUNA 

 General characteristics 



The pelagic and bottom life of our northern seas situated east of Novaya 

 Zemlya is several times poorer in numbers than that of the Barents Sea, but 

 as to the qualitative variety of its benthos the fauna of the Kara Sea is not 

 much inferior to that of the Barents Sea. This is all the more remarkable, 

 considering the much more severe climate of the Kara Sea, its smaller size 

 and its inferiority to the Barents Sea as regards the variety of its biotopes. 

 For instance, all littoral fauna is absent from the Kara Sea, and since it does 

 not contain the macrophyte growths so characteristic of the upper level of the 

 Barents Sea sublittoral, very many forms peculiar to this level in the Barents 

 Sea are absent from the Kara Sea. 



