Abstracts

Water Ecosystems

The basic purpose of modelling of Khanka Lake ecosystem is the research of dynamics and production of ichthyocenosis with anthropogenous actions. It is important to describe functioning of ecosystem because ichthyocenosis occupies the upper trophical levels, and its performances (structure, efficiency, dynamics) in many respects are determined by the lower levels. The basis of modelling is made with classical representations about circulation of substance and balance of power streams in ecosystems. Solar radiation, hydrological, thermal, and hydrochemical conditions of a reservoir is taken in models. The hydrooptical singularities of Lake and anthropogenous actions (irrigation for rice systems, industrial and household use of water, fish yield and fish breeding) are taken into account.

The complex of models from three structurally and informational interconnected levels is developed by modelling of Khanka Lake ecosystem. On first level in search model, common dynamics of ecosystem is obtained. On second level in the extended model, the detailed elaboration of ichthyocenosis is carried out. On third level with the help of prime models the task of searching of optimum conditions of exploitation of ichthyocenosis is solved. For all three levels of models without anthropogenous actions and at average year’s values of the factors of an exterior medium the periodic solutions (with phase per one year) are obtained which will be coordinated to the yield-biological data. The estimations biological and fish productivity of Lake (common, yield, on species) are obtained as a result of the analysis of modelling dynamics of Khanka Lake ecosystem since 1931 year. The structural modifications in ichthyocenosis are characterized by substitution of valuable trade fishes by unvaluable species. One result of modelling is the optimum equilibrium strategy of a fish yield with substantial growth common annual yield of valuable species of fishes. At modelling some hypotheses about functioning water ecosystem were used. The process primary production in reservoirs in many respects depends on selective slacking of solar radiation by components of a water medium. Photosynthesis processes are dependent on length of a wave of solar radiation, character and concentration of suspensions. The process of their inflow in a water medium from ground adjournment is essential to stabilization of circulation of biogenous elements in shallow reservoirs We took into account qualitative singularities of various types of a feed at modelling of trophic interactions. These singularities will be coordinated with biological by representations about suitability of individuals more high level to more concentrated food.

Note. Abstracts are published in author's edition

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