CHARACTERISTICS OF THE PIKOPLANKTON OF THE KUIBYSHEVSKY RESERVOIR IN AUGUST 2014

The characteristics of the structure and spatial distribution of heterotrophic and autotrophic picoplankton in the lower part of the Kuibyshev reservoir in August 2014 are presented in the paper. The total abundance of picoplankton varied within (0.55–11.27) × 106 cells/ml (on average 2.96±2.13×106 cells/ml), biomass – 11.48–372, 76 µgC/l (82.51±72.85 µgC/l), which corresponded to the mesotrophic-eutrophic level of productivity. Single free-floating heterotrophic bacteria, mainly cocci and cocobacilli, predominated in picoplankton. Picocyanobacteria formed 2.2% of the abundance and 20.3% of the biomass of picoplankton; colonial forms were found only in 29.4% of the samples, and no colonies were found in the samples of the Ulyanovsk Reach and Cheremshansky Bay. During the studied period in the Kuibyshev reservoir, the spatial heterogeneity of autotrophic picoplankton in comparison with heterotrophic, was more pronounced. Our data indicate the significant role of picoplankton in the ecosystem of the Kuibyshev reservoir in the late summer period.