Long-term studies (1998–2018) of shallow lakes Krugloe and Krutoe (Russia) were carried out. The trophic status of the lakes was estimated using physicochemical parameters of water and the indicators of zooplankton. Physicochemical studies of Krugloe and Krutoe lake water make it possible to classify these reservoirs as eutrophic according to their trophic status. The lakes are characterized by low water transparency, a high content of organic substances in water, the “blooming” of water is observed periodically, accompanied by the increase of pH to 8–9 units. The zooplankton communities of Krugloe and Krutoe lakes are characterized by relatively low species richness, the dominance of a small number of species, and the predominance of species that are indicators of eutrophic waters. Quantitative indicators of zooplankton are characterized by significant fluctuations in values over the years, the prevalence of rotifers. They showed that zooplankton community is a good indicator of the trophic state of lakes. Such indicators of zooplankton communities as the composition of dominant species, their number, the presence of indicator species, the quantitative indicators of zooplankton and individual taxonomic groups, and the average individual mass of the zooplankton can be used to characterize the trophic status of lakes. They can be recommended for use during monitoring of the lake condition in the Volga-Kama State Natural Biosphere Reserve.

No abstract

No abstract

The article presents the results of monitoring of hydrochemical composition and structure of plankton communities in the water area of the Saralinsky part of the Volzhsko- Kamsky Reserve. The maximum indicators of the species richness, abundance, and biomass of algae, as well as zooplankton biomass, are noted in the ducts. A reliable relationship between the indicators of the quantitative development of phyto- and zooplankton and the content of dissolved oxygen is established. The statistic relationship between phyto- and zooplankton biomass is shown. In phytoplankton the massive development of Planktothrix agardii Gomont is noticed. This fact shows the changes in the complex of the dominant species of blue-green algae in the Kuibyshev reservoir.

The article discusses the results of long-term monitoring of the hydrochemical state of different types of lakes in the Raifa part of the Volzhsko-Kamsky State Nature Biosphere Reserve (Republic of Tatarstan). The comparative characteristics of the chemical composition and water quality of flowing and drainless lakes are given, and the multiplicities of exceeding the maximum permissible concentrations of pollutants in the summer period of 2016-2020 are revealed. It is noted that flowing lakes with a swampy catchment area in the Ser-Bulak river valley are most susceptible to biogenic load. High concentrations of heavy metals are associated with the accumulation of organic substances in these reservoirs.