804 



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



population (with mean biomass of 356 g/m 2 , a maximum of 1 kg/m 2 , and 

 200 specimens per 1 m 2 ) (Fig. 397) which can maintain itself there, feeding on 

 the detritus which is rolled to and fro on the flat, densely packed sand. 

 Each ecological group comprises a few biocoenoses with various dominant 



Fig. 399. Distribution of the total benthos biomass in Sea of Okhotsk (Savilov). 



forms ; this is the result of complex bottom topography, the variety of bottom 

 soils, the complicated system of water circulation and the changes in tempera- 

 ture. 'Bivalve filter-feeders (Cardium sp., Mactra sp. and others)', writes 

 Savilov, ' are predominant in some areas of development of the mobile sestono- 

 phages ; in others they are replaced by the sestonophage Echinarachnius sp., 

 which in its turn gives place to species of Amphipoda of the family Ampelis- 

 cidae. 



