Meromixis and seasonal dynamics of vertical structure of Lake Uchum (South Siberia)=Меромиктический режим и сезонная динамика вертикальной структуры озера Учум (Южная Сибирь)

Abstract

For the first time the seasonal dynamics of the vertical structure of the small salt Lake Uchum, located in the steppe arid zone of the South of Siberia (the Krasnoyarsk Territory), was studied in detail. It is shown that this lake is a meromictic water body. A heterogeneous vertical distribution of plankton organisms and a dense population of purple sulfuric bacteria in the redox zone were revealed. The taxonomic composition and seasonal dynamics of phyto- and zooplankton have been described. Presumably, the meromixis of Lake Uchum is due to the inflow of fresh water to the surface of the saline water body during the rise of its level in the early 20th century, similar to the Shira and Shunet lakes located nearby. The processes of salt displacement into the solution during the formation of ice, as well as the precipitation of salts in the winter, also contribute to the maintenance of permanent stratification. The obtained information on the current state of the lake can be useful for reconstructing the climate by bottom sediments, as well as for creating models of water quality and studying the therapeutic properties of lake mud.