Main natural factors determining seasonal and long-term dynamics of zooplankton from Lake Kulundinskoye (Altai Krai)
The paper presents the findings of studying the influence of main natural environmental factors on long-term (2000-2020) and seasonal (from April to October) dynamics of zooplankton from large hypergaline lake Kulundinskoye located in the Kulunda steppe (Altai Krai, Russia). We studied the relationship of 16 key indicators of zooplankton structure (its abundance and biomass as a whole and in major taxonomic groups, i.e., rotifers, paddleheads, branchipeds and gill- footed crustaceans as well as individual stages of a life cycle and a sex ratio in Artemia population) with 17 hydrophysical and hydrochemical indicators (temperature, density, pH, total salinity, hardness, alkalinity, Cl-, NO2-, NO3-, SO42-, PO43-, NH4+, Fe23+, Ca2+, Mg2+, K+, Na+, monthly permanganate oxidizability (2017-2020) and average annual (for a growing season) data for 2000-2020. The influence of the studied factors on features of Artemia crustacean population (abundance, biomass, age and sex structure) dominated in zooplankton of this lake was analyzed as well. In different years, hydrophysical and hydrochemical regime of lake Kulundinskoye may vary significantly thus affecting zooplankton indicators. The statistical analysis of environmental factor impacts on zooplankton structure of the lake proves better results reliability when using monthly hydrophysical and hydrochemical data rather than averaged over the research period (April-October). The revealed man-induced changes in zooplankton structure are mainly due to the stimulating effect of increased salinity on Artemia population and its depressing influence on other taxa. Long-term dynamics of zooplankton is characterized by a complex cyclicity of water salinity and productivity of Artemia population (the 10-year and, possibly, shorter and longer cycles), which in turn depends on periodic changes in moisture content of the lake catchment.