IS IT POSSIBLE TO RESTORE THE ARCTIC LAKE ECOSYSTEMS AFTER LONG-TERM POLLUTION?

Intensive development of mineral resources of the Arctic regions has led to anthropogenic pressure on ecosystems. Using the example of the long-term anthropogenic pollution of the subarctic Lake Imandra with the sewage of the mining and industrial complex, the dynamics of changes in ecosystem indicators for more than 70 years is considered, an analysis of the newly formed lake modification that is significantly different from the natural state is given. Chemical water composition and the ecosystem structural components (phyto, animal plankton, zoobenthos and fish fauna) are analyzed in following periods: 1) pre-industrial in the natural background state; 2) industrial development of deposits on the shores of the lake and intensive pollution; 3) significant reduction of anthropogenic impact and; 4) the current state.
The main regularities of the aquatic ecosystem variability under anthropogenic pressure are revealed that have led to the coenosis degradation and massive fish diseases. From the point of view of ecological theory, an explanation is given of the modification paths and the impossibility of the lake return to its natural state. It is revealed that the climatic factor along with the entry of biogenic elements have led to the eutrophication of the lake and the coenosis adaptation to new conditions including the appearance of introduced species, the increasing role of thermophilic and eurybiontic forms in the coenosis and utilization of nutrients in biogeochemical cycles, which corresponds to more stable newly formed modification ecosystems. Thus establishing that restoration of the ecosystem with natural characteristics is impossible.

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