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



the Barents Sea among the low Arctic and sub-Arctic fauna (bipolar forms) be 

 abandoned. It can be maintained with confidence that the acclimatization possi- 

 bilities along these two lines merit further study. 



Zoogeographical characteristics 



Zoogeographical subdivision. Before the appearance of K. Derjugin's mono- 

 graph (1915) on the fauna of the Kola Guba, the question as to which zoo- 

 geographical region should include the Barents Sea had not been properly 

 studied. This question was touched on only in passing when establishing the 

 boundaries of different regions. 



Simultaneously with Derjugin, N. Hofsten (1915, 1916) was working out a 

 scheme for the zoogeographical subdivision of the Barents Sea. The opinions 

 of G. Broch (1927), who worked on the zoogeography of the northern parts 

 of the Atlantic for several decades, are also interesting. The boundaries 

 drawn by Hofsten and those of Broch differ considerably (Fig. 73). Broch 

 (1927) starts the southern boundary (pan- Arctic in Hofsten's sense) of the 

 Arctic region from the North Cape, drawing it along the littoral shallow of 

 Norway. 



On the contrary, Hofsten, following Appellof (1912), includes the northern, 

 eastern and southeastern parts of the Barents Sea in the Arctic region, assign- 

 ing all the southwestern half of the Sea to the transitional boreal Arctic zone. 

 The boreal region, in Appellof's opinion, stretches from the North Cape 

 southwards. 



K. Derjugin (1927), who also studied Arctic fauna in detail, came to the 

 following conclusions on the basis of his own work. He limits the Arctic 

 region to the area with a deep floor temperature of 0° and below. Its southern 

 boundary begins at the eastern Murman Peninsula near the entrance to the 

 White Sea and extends to the northeast, north and northwest to Bear Island. 

 This boundary almost coincides with the limit of the greatest southward 

 movement of floating polar ice in winter. Derjugin considers the transitional 

 region of mixed waters and fauna as much more significant than Appellof and 

 Hofsten, ascribing to it the importance of a separate zoogeographical region 

 (the boreo-Arctic region of the two investigators mentioned). In Derjugin's 

 opinion 0° to 5° or 6° is the typical temperature of this region ; moreover, as a 

 rule, no ice cover is formed there. Hence Derjugin includes about one-third 

 of the whole of the Barents Sea in this region, which he calls the sub-Arctic. 



Since Derjugin's investigations A. Schorygin (1928) was the first to survey 

 the problem of the zoogeographical subdivision of the Barents Sea for the 

 echinoderm group. This investigator has based his scheme on a statistical 

 count of the frequency of occurrence of certain individual forms. Derjugin's 

 boundaries between the Arctic and sub-Arctic benthos were corrected by this 

 indirect but quantitative method. The boundary had to be moved 200 to 300 

 km to the west. Schorygin also drew a more accurate boundary between the 

 low Arctic and high Arctic sub-regions in the northern and southeastern parts 

 of the Barents Sea. His conclusions were later confirmed by a comprehensive 

 quantitative analysis of the bottom fauna carried out by V. Brotzkaya and 

 L. Zenkevitch in 1939 for the whole Sea and by Z. Filatova (1938) for the 



