2. Communities of the Arctic Waters . 

 (E. A. Zelickman) 



The cyclical nature of the functioning, i.e., the presence of popu- 

 lation waves in the Arctic ecosystem, is a general property of this system, 

 reflected in the formation of all production characteristics. It results 

 from the light limitation of photosynthesis. In an ecosystem which must 

 function in a fluctuating mode, selection fixes only those hereditary 

 changes in organisms which correspond to a broad reaction norm. Compensa- 

 tory paths of stabilizing selection are primarily limited to multiplication 

 (Shmal 'gauzen, 1968). With a brief season of abundant food, selection 

 goes to higher fertility, and selective elimination may be directed toward 

 various phases of ontogenesis. In this case, the reproductive potential of 

 the species, as a rule, which is not realized in the Arctic community, may 

 manifest itself as compensation. Therefore, in the Arctic community, only 

 "opportunistic species" with high ecologic valence: high numbers of 

 population, flexible reaction to unfavorable changes in the environment, 

 high growth rate of the population under favorable conditions and high 

 mortality, can blossom. The dominant species of this profile in the 

 Arctic community can be compared (Margalef, 1968) to a thermostat, consuming 

 a great deal of energy while acting as a regulator. This type of "equipment" 

 withstands extreme conditions, converting fluctuations in the environment 

 to the benefit of the system. Just what are the means of this damping? 



If the production of plankton communities is interpreted (Cushing, 

 1959a, b, 1969) as a result of contradictory relationships among populations, 

 the course of the curve of creation of products is determined by the time 

 interval between the peak of blooming of the phytoplankton and the moment 

 of greatest intensity of consumption. Arctic and boreal communities differ 

 essentially only in the length of this interval, proportional to the distance 

 from the Pole. In other words, an Arctic community as a whole has its own 

 unique "system time," and in each season the community must adapt to this 

 system time, synchronizing its state with the time. The balance between 

 producents and consumers in this interpretation is a characteristic which 

 is more temporal than quantitative. Therefore, the synchronization of the 

 processes of creation of biomass and its destruction at the next trophic 

 level is one of the leading trends in selection in the Arctic ecosystem. 

 Idioadaptation at the species level should support temporal contact and the 

 normal sequence of the cycles, while the equilibrium between production and 

 consumption is checked by the entire system of mechanisms inherent in the 

 community as a whole. One of the indirect mechanisms synchronizing the 

 system is the high P/B coefficient (for values of indicators, see 

 Kamshilov, 1955, 1958; Timokhina, 1968, 1972), corresponding to the 

 seasonal asymmetry of the curve of food resources. 



The obligatory pulsation in the status of the community may be a 

 specific method of stabilization of the system, but not a method of its 

 disruption. The fluctuation processes in the Arctic encompass the entire 



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