Influence of Environmental Factors on the Dynamics of Zooplankton in Lake Kulunda (Western Siberia)

The results of studying the influence of the main natural environmental factors on the interannual (2017–2021) and seasonal (from April to October) zooplankton dynamics of the large hypersaline Lake Kulunda located in the Kulunda steppe (Altai krai, Russia) are presented. The relationship of 13 main indicators of the structure of zooplankton (number and biomass in total, the main taxonomic groups: rotifers, copepods, cladocerans, and branchiopods, as well as different stages of the life cycle of Artemia) with the main hydrophysical and hydrochemical indicators (temperature, density, salinity, and pH of water) was analyzed separately by monthly and average annual (for the growing season) values. The influence of the studied factors on the characteristics of the brine shrimp population (number, biomass, and age structure), which dominated the zooplankton of this lake, was analyzed in more detail. It was revealed that the hydrophysical and hydrochemical regimes of the lake in different years are subject to significant changes and are reflected in the indicators of zooplankton. Changes in the structure of zooplankton under the influence of natural factors are mainly due to the stimulating effect of an increase in water mineralization on the Artemia population and its depressing effect on the brackish fauna. With a decrease in water salinity less than 100 g/dm 3 since 2017 (127 g/m 3 ) to 2021 (96 g/dm 3 ) maximum (summer) Artemia biomass decreased from 167 to 17.7 g/m 3 . At the same time, the maximum biomass of rotifers, cladocerans, and copepods increased from 0.003, 0, and 0.63 to 6.21, 1.35, and 2.65 g/m 3 respectively.