Brownification and its consequences for the ecosystems of Lake Onego and Vygozerskoe reservoir under influence of climatic and anthropogenic factors

Abstract

The consequences of climatic changes in the conditions of anthropogenic load weakening are considered for the ecosystems of the largest lake-reservoirs in the northwestern region of Russia (Lake Onego and Vygozerskoe reservoir). The catchment areas of these water bodies are rich in bogs. The rise of the humic substances flow became a new regulatory factor in the functioning of these reservoirs due to an increase in winter river flow in conditions of climate warming. Geochemical indicators of the increasing influence of the catchment area on the water chemical composition in the studied lakes were a simultaneous increase in the color of water (brownification), the concentration of iron and carbon dioxide, and a decrease in pH. The accumulation of iron at the bottom of Lake Onego caused inhibition of deep-water benthic communities. The state of benthos of Vygozerskoe reservoir is associated with the consequences of influence of pulp and paper mill wastewater, the highest toxicity of which was observed in the previous period.