Structural Changes of Phyto- and Zooplankton under the Influence of Climate Change and Anthropogenic Load (Lake Baikal, Russia)

The results of a contemporary study of hydrochemical parameters, structure, and quantitative indicators of phyto- and zooplankton in the Maloe More Strait of Lake Baikal are presented. When comparing new data and those obtained in the 20th century, a number of changes are observed in the functioning of the phyto- and zooplankton of the strait in recent years, similar to other areas of the lake. The main rearrangements are noted for spring phytoplankton: interannual cyclical dynamics with the maximum development of large-cell diatoms of the Baikal complex is disturbed; the structure of dominant species has changed. Due to a sharp increase in the rotifer abundance, the zooplankton abundance in the pelagial has increased by an order of magnitude. In 2021, with the intensive vegetation of diatoms, all zooplankton groups were suppressed. In Mukhor Bay, the changes were associated with an increase in the rotifer abundance persisting until 2021. In 2021, a decrease in the total plankton abundance was noted, but the relative share of taxonomic groups did not change, and rotifers dominated.