The Kuybyshev Reservoir Volga Reach Water Quality Assessment by the Zooplankton Status

The object of the study were three different in their hydrological characteristics, as well as the degree of anthropogenic load on them (in the form of sewage from the adjacent territory), the area of the water area of the Volga reaches of the Kuibyshev Reservoir, where there are deposits of nonmetallic building materials. Studies were conducted during the vegetation period 2014-2015. They included physical/chemical studies and studies of the state of zooplankton. Total 311 samples of zooplankton were collected and processed. During the study, 30 species of zooplankton organisms were recorded: 7 species of Rotifera, 7 species of Copepoda and 16 species of Cladocera. The richest in terms of the quantitative diversity of species was No. 3 site. Prevalent in terms of number and biomass of organisms – site number 1. Quantitative indicators of zooplankton were observed in 2015 compared to 2014. This is explained by the fact that 2014 was warmer than 2015. The oxygen regime of 2014 was also better than that of 2015. The turbidity of water in 2014 was below the turbidity of water in 2015, the quality of water in the second year of research deteriorated compared to the first in a number of indicators, such as COD, compounds copper, zinc, manganese, oil products. The mid-vegetation indexes of saprobity for the indicated observation period make it possible to attribute these sections of the Volga reach of the Kuibyshev reservoir to the β-mesosaprobic zone, which corresponds to the third class of water quality - moderately polluted water. Proceeding from the obtained values of the Shannon and Pielu indices, the zooplankton of the studied sections of the Volga reaches of the Kuibyshev reservoir has a rather low species richness with a rigid type of dominance, which characterizes it as mesotrophic. The ratio of groups of organisms and the dominance of individual species indicates a deterioration in water quality over a two-year period of research, which is confirmed by the research conducted by the Federal State Unitary Enterprise «UGMS RT».