Current state of the ecosystem of Lake Vedlozero and its biological resources (Republic of Karelia, northwestern Russia)

Abstract

The results of a study of the current state of the ecosystem of Lake Vedlozero (Republic of Karelia, northwestern Russia) in 2021-2022 and its changes over 30 years are presented. In recent years, in the summer-autumn period, algal blooms, including toxic cyanobacteria, have intensified in the lake, which affects the quality of the water and fish habitat. Active algal blooms are still local and are observed mainly in areas of the lake with intense anthropogenic impact. In general, the Lake Vedlozero ecosystem at the present stage corresponds to mesotrophic status in terms of hydrochemical and hydrobiological indicators.The lake’s aquatic communities have not undergone noticeable changes since the 90s of the last century. The concentration of chlorophyll a has increased by an order of magnitude (3 µg/l in 1992 and 11-90 µg/l in 2021). Planktonic communities are in a stable state and provide a stable food supply for planktivorous fish. The composition and structure of benthic communities also did not change over the 30-year period.To calculate fish productivity, an analysis of the distribution of organic matter and energy in the food web of the lake ecosystem was carried out using the balance model of V.V. Boulion. The results of the model calculation are in good agreement with empirical data. Thus, the model can be used for calculating fish production and estimating possible catches in the lake. According to the model, possible catches amount to a third of fish production and are equal to 9.6 kg/ha. For the first time in 2021, an alien species of the American rotifer Kellicottia bostoniensis was recorded in Lake Vedlozero, which may indicate that the range boundary of this species is moving northward against the backdrop of continuing warming of the regional climate in northwestern Russia.