encounters a situation in which the waters rise from depths which are not 

 very great, so that the waters which are rising are already populated by 

 a developed community. In this case, the entire system, even in the zone 

 of its formation, takes on a number of features which are characteristic 

 of comparatively mature communities (Vinogradov, Semenova, 1975: Flint, 

 1975). Finally, changes in wind speed also cause changes in the rate of 

 upwelling, while the axes of individual spots of upwelling of the water may 

 be significantly deflected, leading to mechanical scattering of concentra- 

 tions of zooplankton and phytoplankton at various depths (Stroqonov, 

 Vinogradov, 1975). 



In SDite of the fact that, under actual conditions, there is constant 

 redistribution and mixing of communities, it is possible to observe com- 

 munities in the early stage of maturity, and use them to obtain some idea 

 of the basic regularities involved in succession changes. Obviously, in 

 order to clarify the cause-and-effect dependence of phenomena and processes, 

 we must study the entire picture of formation and development of the eco- 

 system. Isolated analysis of individual moments of its existence cannot 

 allow us to understand either the causes of the observed state of the 

 system, or its changes as time goes by. 



2.3 The Succession of a Pelagic Ecosystem 



The development of an ecosystem as time passes--its succession--is 

 one of the fundamental concepts of modern ecology. In the opinion of 

 Margalef (1958), succession in ecology occupies a position as important 

 as that of evolution in general biology. 



Succession is a process of self-organization, which occurs in any 

 ecosystem. Margalef (1968) believes that any system consisting of repro- 

 ducing and interacting organisms and the environment must continue to 

 develop in the direction of creation of an organization for which the 

 value of entropy per unit of information stored and transmitted is minimal. 

 In the course of succession, structures (systems) are preserved which are 

 most able to influence the future at the cost of the least amount of energy. 

 In other words, the process of succession is equivalent to the process of 

 accumulation of information. As it occurs, the system changes in the 

 direction of achievement of a certain asymptotic steady state. In the 

 initial stages, the community receives its primary influx of information 

 from the surrounding (abiotic) environment, whereas in the more mature 

 stages, the significance of information transmitted from some components of 

 the community to others increases (Margalef, 1968). 



This understanding of the succession changes in an ecosystem includes 

 changes occurring in developing communities in the pelagic zone of the 

 ocean. It is broader than the classical concept of succession, developed 

 by continental geobotanists , which has caused some authors to express doubt 

 as to the correctness of application of this term to the process of develop- 

 ment of aquatic systems. 



However, the differences between continental and oceanic systems are 

 not differences of principle, but rather concern only certain of the 

 peculiarities of the phenomena and their quantitative expression. 



16 



