degree of mobility of animals and methods of their attachment to the 

 bottom. The stucjy of the spatial distribution of trophic groupings 

 required simplification of the classification. M. N. Sokolova (1956, 

 1960) used only the source of food as a criterion for differentiation of 

 trophic groupings, and distinguished three groupings: detritophages, 

 unselectively swallowing the bottom and feeding on buried detritus from 

 the uppermost layers of the bottom; detritophages which collect detritus 

 from the surface of the bottom; and sestonophages, which consume 

 suspended detritus. 



The distribution of trophic groupings was found to be directly 

 related to the mode of sediment accumulation which determines whether 

 the main portion of the detritus will be suspended in the lowest layers 

 of water, or precipitated onto the surface of the bottom, or buried in 

 the bottom. This allowed M. N. Sokolova (1964, 1966) to formulate the 

 concept of the trophic zone. The trophic zone refers to a section of the 

 bottom occupied by biocenoses of a single trophic type, i.e., with 

 predominance (by weight) of a single trophic grouping. The trophic zone 

 in all its parts is charcterized by similar conditions of feeding for 

 benthic invertebrates, i.e., by a similar type of distribution of 

 detritus. 



The conditions for predominance of sestonophages arise when the 

 erosion or transfer of sediment predominates over its precipitation. 

 Conditions for predominance of detritophages of both groups arise when 

 the process of precipitation of particles predominates over a given 

 section of the bottom (Turpayeva, 1954; Sokolova, 1956, 1960). 



Analysis of the data on the development of trophic zones on the 

 shelves of the seas of the USSR, the particle-size composition of bottom 

 deposits and the content of organic matter in them has allowed us to 

 reveal the interrelationship between these characteristics. Based on 

 them, a hydrodynamic regional ization of the Barents, Karsk and Okhotsk 

 Seas was performed, based on the relationship of areas of the bottom 

 occupied by various trophic zones (A. P. Kuznetsov, 1970, 1974). It was 

 found possible to distinguish the types of shelves according to the 

 predominant type of dynamics of the water, i.e., the fraction of the 

 bottom area occupied by a given trophic zone (A. P. Kuznetsov, 1974; 

 Kuznetsov, Neyman, 1975). The following types of shelves were 

 distinguished: 1) shelves with active dynamics of the waters near the 

 bottom; 2) shelves with weakened dynamics of the waters near the bottom; 

 for both types, we can assume that the dynamics of the waters near the 

 bottom are identical throughout their entire area; 3) shelves where 

 there is spatial heterogeneity in the distribution of the dynamics of 

 the waters near the bottom. Shelves of type 1 are narrow and steep, 

 entirely occupied by zones in which sestonophages predominate. They 

 include the shelves of the island arcs with clear predominance of 

 attached sestonophages. In these areas, in places where silty sediment 

 accumulates, we also find detritophages. Shelves of type 2 are ideally 

 occupied by a single zone of predominance of detritophages. This type 

 includes the shelf of Hudson Bay, with its long ice-covered season, 

 reducing wave mixing, its characteristic bottom configuration and 

 relatively mild tidal fluctuations of the level. It can be expected 

 that the reduced dynamics of the waters near the bottom are 



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