250 



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



four groups: (1) high Arctic, bathypelagic with a preponderance of echino- 

 derms, Foraminifera, small-sized molluscs and polychaetes ; (2) high Arctic 

 shallow-water forms, also with a preponderance of echinoderms, mostly 

 small brittle stars ; (3) high Arctic forms from the littoral shallows with a pre- 

 ponderance of molluscs ; and (4) low Arctic Barents Sea forms. 



g^ 5 



6 



Ш2 ГТТТТ1 4 



Fig. 107. A chart of the distribution of the bottom biocoenoses of 

 the Kara Sea (Filatova and Zenkevitch, 1957). 1 Portlandia aestua- 

 riarum ; 2 Portlandia arctica ; 3 Astarte borealis placenta ; 4 Ophiocten 

 sericeum; 5 Ophiopleura borealis; 6 Ophiopleura-Elpidia; 7 Spio- 

 chaetopterus typicus. 



Quantitative distribution of benthos. In spite of its great qualitative variety the 

 bathypelagic fauna of the Kara Sea is much inferior in numbers to the benthos 

 of the southern half of the Barents Sea (Fig. 109) ; however, in some regions 

 of the Kara Sea it is higher than the benthos biomass of its northern part. 

 The average benthos biomass of the western part of the Sea is 50 g/m 2 . 



As can be seen from the chart, the benthos biomass of the central part of 

 the Sea, in the area of brown muds, is less than 5 g/m 2 , and at times is no more 



