Change of spatial distribution in the ichiotocenosis of the shabolat estuary in the process of its anthropogenic transformation

Abstract

Consequences of Shabolat estuary natural ecosystems transformation under the influence of anthropogenic factors are reflected in the composition of ichthyocenosis, changes in the basic population characteristics of the most mass species.The purpose of the work was to find out the spatial distribution of the Shabolat estuary most massive representatives of the ichthyocenosis in terms of its anthropogenic transformation.Material and methods. The material for the study was selected from industrial fishing gear in the spring, summer and autumn periods of 2009-2012. A complete biological analysis of fish (goby round, goby grass, flounder, flounder, mullet pilengas, etc.) was carried out according to the conventional method.Result. The regularities of formation of ichthyocenosis largest masses populations were studied depending on: water salinity, connection with adjacent water areas, fish acclimatization and introduction, anthropogenic loading and peculiarities of spatial distribution of ichthyocenosis largest masses populations in aquatics.The most important Shabolat estuary ichthyocomplex components include representatives of the Gobiidae family, the Platichthys luscus population and the mullet family representatives.Of particular interest to the members of the goby family are the mass species of gobies: the round goby Neogobius melanostomus and the grass goby Zosterisessor ophiocephalus, which are able to hibernate and reproduce in the estuary. This is an important link in the food chains of the reservoir. By entering into competition with other representatives of ichthyocenosis, they significantly affect the state of the forage base and production capacity of the estuary.Representatives of the mullet family and gloss flounder are distributed in the estuary deep water areas and in areas with maximum salinity.Conclusions. It has been established, that in the conditions of anthropogenic transformation of the estuary, in the last 35-40 years, the round goby and grass goby numbers and distribution range have decreased. In bulk, they have survived only in reservoir small, local areas, due to the deterioration of reproduction conditions and the degradation of the zoster and reddest associations. The main reasons for the decline in the size and distribution range of gobies in the Shabolatsky estuary was their mass death as a result of a large-scale environmental catastrophe and reproduction conditions deterioration. The reason for the significant decrease in the flounder and mullet number and distribution range was the mass death in 1992, as well as changes in the salinity of the Shabolat estuary