FORMATION OF ZOOPLANKTON IN THE BOGUCHANY RESERVOIR DURING ITS FILLING

Abstract

For the first time, we present the materials of the spatial distribution of qualitative and quantitative indicators of zooplankton in the first year of top water level (TWL) in the Boguchany Reservoir. We indicate the dynamics of the formation of the zooplankton community in the Upper section of the reservoir during its filling (from 2013 to 2015). The Irkutsk, Bratsk, and Ust-Ilimsk reservoirs influence the composition and structure of zooplankton in the Boguchany Reservoir that closes the cascade of the Angara HPPs, and there is a great similarity of the crustacean and rotifer fauna with the upstream artificial reservoirs. During the study period (from 2013 to 2017), the plankton fauna included 84 species from 49 genera and 23 families. The horizontal distribution of quantitative indicators throughout the water area of the reservoir had a mosaic pattern. The relative and absolute proportion of rotifers in the composition of zooplankton decreased from the Upper section to the Lower one, and the dominance of crustaceans was opposite. Due to this, the maximum number (129±97.8 thou ind./m3) of zooplankton was recorded in the Upper section, and the biomass (2080±676 mg/m3) – in the Lower section. The obtained unique data on the composition, structure and quantitative development of zooplankton in the Boguchany Reservoir during its formation and filling are important for further monitoring of its state, including the assessment of the feeding of planktonophagous fish and juvenilefish.