views of the proponents of the biologic concept are well reflected by 

 the words of D. N. Kashkarov: "The word biocenosis is constantly 

 applied to widely varied groups of organisms, without the slightest 

 attempt to understand the connections between them, to understand the 

 internal relationships in the biocenosis. ... In this sense hydrobiolo- 

 gists are great offenders. Any isolated accumulation of various organisms 

 is immediately referred to as a biocenosis. . . . The result is a 

 purely formal . . . and therefore fruitless description of phenomena" 

 (1938, p. 271). 



The concept of the biocenosis as a super-organism (Thienemann, 1925: 

 Clements, Shelford, 1939; etc.) has been severely criticized. Particularly 

 important has been the criticism from those who look upon a community as 

 a continuum. The view of a community as a group of unrelated species, which 

 react similarly to environmental conditions and are distributed along a 

 gradient of environmental factors in accordance with the degree of tolerance 

 of each species, agrees well with the concept of the community as a 

 statistical unit, but is incompatible with the biologic concept of the 

 community. 



The development of the biologic concept of the community was greatly 

 influenced by the development of such concepts as the trophic level, food 

 chain and stages of succession (Elton, 1927, 1934; Kashkarov, 1938, 1945; 

 and others). A new step on this path was the combination of the dynamic 

 aspect of community (succession) with the views of V. I. Vernadsky concerning 

 the biogeochemical role of living matter and the development of the tropho- 

 dynamic concept of ecology on this basis (Lindeman, 1942). The trophodynamic 

 aspect of the study of aquatic ecosystems developed rapidly, leading to the 

 development of the theory of food chains (Riley, 1963a), the quantitative 

 theory of biological productivity of the sea (Gushing, 1959a), the intro- 

 duction to hydrobiology of cybernetic concepts (Margalef, 1956, 1968; 

 Patten, 1959, 1966), and the development of mathematical models of 

 aquatic ecosystems (Riley, 1963; Gushing, 1959a; Vinberg, Anisimov, 

 1966: Lyapunov. 1971; Menshutkin, 1971; Vinogradov et al . , 1971; Odum, 

 1975, etc.). 



The study of the structure of aquatic communities has also led to 

 extremely important conclusions. It has been found that the composition 

 and relations of species in a biocenosis is not unambigiously determined 

 by the peculiarities and mosaic of external conditions (the biotope). The 

 leading species of common benthic biocenoses are selected according to the 

 principle of the least competitive interactions (Ivlev, 1954; Shorygin, 

 1955). If we rank the leading species of a biocenosis in order of mean 

 biomasses, the neighboring species in the series thus produced will 

 generally belong to different trophic groups (Turpaeva, 1949, 1957; A. P. 

 Kuznetsov, I960), and if they are in the same trophic group, they usually 

 belong to different zoogeographic groups (Neyman, 1963a, 1967). This 

 rule, first determined empirically and later confirmed with extensive 

 factual materials, has provided an important confirmation of the value of 

 the Petersen concept of benthic communities. 



Thus, in marine biology, two different views on marine communities 

 have developed; more precisely, two models of marine communities have 



