234 



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



unidentified forms, whereas with the larvae, parasitic crustaceans and the 

 unidentified forms the number is 223 {Table 101). 



Total 



11 



2 



50 



11 



3 

 4 



5 



5 



169 



Kara Sea zooplankton as an indicator of hydrological conditions 

 The sharp differences in the water masses of the Kara Sea, varying in their 

 origin and in the fauna they bring with them, have made it possible for differ- 

 ent investigators of this body of water to pose with particular precision the 

 problem of the biological indicators of the different waters that compose it. 

 (G. Gorbunov, 1934, 1937, 1941 ; E. Gurjanova, 1934, 1936; V. Khmisnikova, 

 1936, 1937; M. Virketis, 1945; B. Bogorov, 1945, and others). As has been 

 justly remarked by Gurjanova, 'One should search for biological indices 

 among forms which, owing to their stenobiotic nature, are restricted in their 

 distribution. The common forms widely distributed throughout the whole 

 Arctic cannot serve as indices. The indifferent forms are uniformly distri- 

 buted throughout the Sea, in places of suitable depths and soils ; they are the 

 indifferent forms of the Barents Sea. However, when these species get into 

 the Kara Sea, they are most unevenly distributed there and depend on the 

 range of the currents. In the conditions of the Kara Sea they become biological 

 indicators of the presence of Barents Sea waters, in which they are distributed 

 about the Kara Sea. On the other hand the most common high Arctic forms 

 — indifferent for the Kara Sea because widely distributed in it — are already 

 becoming rare in the conditions of the Barents Sea and become indicators for 

 Arctic waters, while indicators of the western Atlantic waters would be the 

 boreal species more or less widely distributed in the northern part of the 

 Atlantic Ocean.' 



There is no other marine body of water where the distribution of the fauna 

 gives such clear and abundant illustrations for the understanding of the ori- 

 gin of its masses of water as the Kara Sea. A very large number of plankton 

 and benthos forms can serve as indicators of both fresh and brackish waters, 

 and of waters penetrating from the west from the Barents Sea, and from the 

 north from the central parts of the Arctic basin. Among these it is possible to 

 distinguish the forms belonging to the warm Atlantic intermediate layer and 

 those of the cold Arctic bathyal and abyssal waters. 



