THE BARENTS SEA 



141 



been established by R. Leibson (1939) for the Motovsky Gulf and the general 

 character of the distribution of echinoderms, bivalves and polychaetes in the 

 whole of the Barents Sea may be explained partly by these relationships. 



Distribution and composition of the main communities of the open sea. Intensive 

 quantitative investigations carried out for ten years make it possible to dis- 

 tinguish six basic communities in the bottom fauna of the Barents Sea and 

 about forty secondary variations of these communities (Figs. 55 and 56). It 

 must be kept in mind that these data, obtained by means of a bottom-grab, 

 do not give a sufficiently complete picture of the epifauna, and its actual bio- 

 coenosis range must be wider. For the Barents Sea, however, with its soft 



Fig. 54. Quantitative distribution of total benthos biomass (A) with depth and (B) 

 bivalves, echinoderms and polychaetes on ooze soils of Barents Sea (Idelson). A: 

 Benthos biomass and bottom temperature at the Central Elevation of the Barents 

 Sea (along meridian 35° E). B: 1 Lamellibranchiata ; 2 Echinodermata ; 3 Poly- 



chaeta ; 4 Other groups. 



bottom, and therefore a preponderance of infauna, data of this type may be 

 considered sufficient. 



In the most southwesterly part of the Sea, open to considerable influence of 

 thermophilic Atlantic fauna, a large biocoenosis diversity is observed on 

 shallows of the continent. As has been shown by Z. Filatova (1938) the popu- 

 lation of the littoral sand and rock floor at depths of 60 to 1 00 m along west and 

 east Finmark loses some of its boreal forms, and they are replaced by Arctic 

 ones as we move eastward. Epifauna consisting of different planktophages is 

 here luxuriantly developed. To the west of the North Cape a mass develop- 

 ment of warm-water forms is observed : bryozoans Hornera lichenoides, Id- 

 monea atlantica, Flustra foliacea, soft coral Eunephthya, and the polychaetes 

 Placostegus tridentatus, Hydroides norvegica, Eunice norvegica, Pista cristata 

 and Goniada maculata. The boreal forms of echinoderms and especially sea- 

 urchins Echinus esculentus, Spatangus raschi, Brisasterfragilis, Echinocyamus 

 pusillus, Echinocardium flavescens are very typical. Among the molluscs 

 Astarte sulcata, Pecten auratus, Modiola barbata, Mactra elliptica, Cardium 



