The constancy of the composition of a community and the distinctness 

 of the boundaries between neighboring communities existing in the environ- 

 ment, which has no such constancy or clear boundaries, is possible, as 

 V. N. Beklemishev (1928) emphasizes, only if there is some internal organi- 

 zational factor, due to which certain combinations of organisms are 

 stable, while those intermediate between them are unstable, even if they 

 live under intermediate conditions. The existence of such a factor, 

 however, is hardly axiomatic. There is another point of view, first stated 

 in 1910 by the geobotanist L. G. Ramensky: Vegetation is a continuous whole. 

 The species are autonomous and have no organic relationship with each other. 

 Species which respond in the same way to certain environmental conditions 

 inhabit the same area, but, due to the ecologic individuality of each species, 

 the boundaries of the ranges of various species do not coincide, so that 

 the groups of species merge smoothly with each other. There are no com- 

 munities; there are only coinciding species within the limits of the continuum, 

 This concept has become widespread in geobotanics since the late 1920s, and 

 has extended into marine biocenology. 



The concept of the marine benthic community as a continuum has been 

 developed primarily by A. Lindroth (1935, 1973). In his opinion, the 

 concepts of trophic levels and trophic connections should be applied not 

 so much to individual species as to life forms. The distribution of species 

 in communities depends primarily not on species-specific relationships 

 between them, but rather on their relationships to environmental factors 

 which they all encounter. A sharp gradient in the environmental factors 

 represents a boundary for the extension of many species in the community 

 simultaneously. If the gradient is not great, the species are distributed 

 along the gradient independently of each other, so that a continual 

 distribution develops. The boundaries of a community are not clearly 

 outlined, communities merging one into another. The boundary of distribution 

 of the ecologically dominant species is, naturally, the boundary for the 

 fauna and flora associated with it as well. Lindroth (1973) suggests that 

 homogeneous communities be called coenotypes , that communities with gradually 

 changing composition be called coenocl ines . Among the coenotypes, he 

 distinguishes abiogenic c oenotypes , limited by sharp gradients in abiotic 

 conditions; biogenic coenotypes , related to changes in ecologic dominants; 

 and plateau coenotypes , homogeneous communities with unclear clinal-type 

 boundaries. 



A typical example of a coenocline, according to Lindroth (1935), is the 

 community of soft, silty bottoms. The composition of this community results 

 from external factors. Definite and rather individualized communities may 

 be encountered wherever a dominant species of organism develops, i.e., 

 wherever the coenocline becomes a biogenic coenotype. In the opinion of 

 Lindroth, based on the study of the benthos of Gullmar Fjord (western 

 Sweden), it is quite impossible to distinguish associations for such 

 regions, since the "colonies" gradually merge with each other, with no sharp 

 boundaries. Many other researchers studying the benthos of soft bottoms have 

 reached similar conclusions (Vorob'yev, 1949; Lie, 1968a, 1969, 1974; 

 Lie, Kelley, 1970; Lie, Kisker, 1970). 



8 



