hierarchy of trophic levels in a definite sequence, but with varying 

 intensity. However, in the annual cycle, the production of the community 

 remains relatively stable, since its basic parameters (species composition, 

 numbers, biomass) do not go beyond a certain framework. 



The population waves, as an attribute of all life cycles in the 

 Arctic, facilitate the appearance of new genotypes in the evolutionary 

 arena (Huxley, 1942). The fluctuating mode also influences the boundaries 

 of the area of distribution of Arctic and Arctic-boreal species, which 

 alter their "case" with periodic changes of abiotic conditions. 



The oscillating type of dynamics predetermines the resiliency of 

 the structure of the populations and the strong intraspecies mutual 

 dependence. The Arctic ecosystem, which is self-reproducing in the 

 oscillating mode, to some extent refutes the thesis of the incompatibility 

 of maximum productivity of a community with the status of its highest 

 stability. If we look upon constancy of relationships of biomass of 

 species in a community as one criterion of stability, this constancy is 

 retained on the average over the annual cycle (see below). Obviously, it 

 is more correct to evaluate, in this case, oscillations in numbers as a 

 manifestation of stability (Preston, 1959): They make the community less 

 vulnerable. From the standpoint of evolutionary advantages, this form of 

 stability can be considered most adequate for biological progress, as 

 understood by A. N. Severtsov. 



2.1 . Comparison of the Arctic Ecosystem with Other Productive Systems 



The concept of "system time" allows us to note the deep structural and 

 functional similarity between the ecosystems of the different productive 

 zones and their particular blocks. For example, the "behavior" of marine 

 and fresh-water Arctic communities is similar (Dodson, 1975; Tash, Armitage, 

 1967). 



The shelf-neritic communities of various latitudes, like the Arctic 

 community, are the arenas of seasonal "demographic explosions." The 

 spatial distribution of phytophages and predators in the area of the polar 

 fronts of the Norwegian and Greenland seas (Gruzov, 1963; Pavshtiks, 1972) 

 is similar to that in the region of the West African upwelling (Bainbridge, 

 1972): In both cases at the "line" of the front and in the zone of maximum 

 upwelling, phytophages predominate, with predators predominating around 

 the periphery. There are also analogies in the systems of adaptations. We 

 need but recall the similarity of the life cycles and life forms of 

 Arctic-boreal and neritic euphausiids as a counterweight to the oceanic 

 forms, regardless of their latitudinal distribution (Zelickman, 1968a; 

 Gilfillan, 1972). Convergent adaptations are seen in the upper boreal 

 Calanus finmarchicus and lower boreal C. carinatus , e.g., the winter 

 descent of the stage V copepodites (Bainbridge, 1972). 



The small variety of life forms in the Arctic ecosystem is compensated 

 for by the intensive intraspecies divergences. Within the framework of the 

 Arctic ecosystem, sympatric radiation occurs among the dominating species 

 Calanus , Pseudocalanus , L imnocalanus , Oithona , Parathemisto , Mysis and 



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