1. Simulations of the Functioning of a Pelagic Ecosystem . 

 (M. E. Vinogradov, V. V. Menshutkin) 



The functioning of marine communities is determined by a complex 

 set of relationships between populations, based on evolutionary 

 adaptation of organisms to existence under the conditions of the system 

 in question. The morphophysiologic peculiarities of the organisms, 

 their genetic characteristics, behavioral reactions, etc., play a 

 definite role in this process. Various types of connections arise 

 between the components of communities, but it can be considered that the 

 basic connections in communities, integrating them and defining the 

 basis of their structure and productivity, are food connections (Elton, 

 1946; Vinogradov, 1970b; and others). Therefore, the study of trophic 

 relationships within a community, estimates of the flows of energy 

 through the biologic system and its utilization by the various trophic 

 groups, yield the most essential information concerning the functioning 

 of communities. 



For aquatic, and particularly pelagic, communities, the energy 

 principle of investigation is especially effective. The significant 

 homogeneity of the biotope determines the leading role of trophic 

 connections in the regulation of the development of the aquatic 

 ecosystem as a unit whole. Connections which are not directly related 

 to feeding play a distinctly secondary role in oceanic pelagic 

 ecosystems, in contrast to marine benthic and, particularly, terrestrial 

 ecosystems. From this standpoint, pelagic ecosystems are the simplest 

 for modelling and at the present time, probably, it is only for these 

 systems that we can attempt to construct a sufficiently complete model 

 of the balance relationships. Furthermore, the abiotic conditions, 

 which directly effect the functioning of the community, can be 

 quantitatively estimated with ease for the pelagic zone. 



The study of the energy characteristics of the population of the 

 deeper levels, requiring experimental observation, as yet encounters 

 significant methodologic difficulties; therefore, we must limit 

 ourselves to analysis of the communities of the surface (productive) 

 zone. These communities include practically all of the phytoplankton 

 and about half of the zooplankton of the waters of the ocean and, in 

 fact, determine the productivity of the ocean. The study of their 

 functioning is of singular theoretical and practical interest. 



1.1 Statement of the Task of Modelling of Balance Relationships in 

 Oceanic Pelagic Ecosystems 



The construction and investigation of mathematical models of the 

 functioning of pelagic ecosystems has a rather long history (Patten, 

 1968). The following works are probably among the most interesting: 

 Riley et al . (1949), Steele (1962, 1974), Vollenweider (1965), Dugdale 



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