Ecological trends of spatial distribution and of size-morphological structure of bacteriobenthos in the Kuibyshev Reservoir, the Volga River, Russia

• Published in: IOP conference series. Earth and environmental science 2021-07, Vol.818 (1), p.12049
• Main Author: Sherysheva, N G
• Format: Article
• Language: English
• Subjects: Abundance; Bacilli; Backwaters; Bacteria; Biomass; Bottom sediments; Composition; Decomposing organic matter; Downstream; Grain size; Humus; Lakes; Morphology; Organic matter; Reservoirs; Rivers; Sediments; Spatial distribution; Trends; Upstream
• ISSN: 1755-1307; 1755-1315
• DOI: 10.1088/1755-1315/818/1/012049

The abundance and biomass of bacteriobenthos, as well as morphological and size structure of bacteriobenthos community have been studied in 2016 in the Kuibyshev Reservoir. Three areas of the reservoir, differing by the features of the spatial distribution of bacteriobenthos, were defined: the downstream area of lake-like reaches, the mixed area of the Volga and Kama rivers confluence, and the upstream area of variable backwater. Trends in the increase in the number and biomass of bacteria along the longitudinal axis from the upstream reaches to the dam were revealed in the downstream area of lake-like reaches and in the upstream area of variable backwater. The mixed area of the Volga and Kama rivers confluence was characterized by a patchy distribution of bacteriobenthos. The abundance of bacteria in the bottom sediments was 3.6-10.5 × 10 9 cells mL −1 , biomass, 263-971 μg mL −1 . There was an increase in the abundance and biomass of bacteria in the area of the Volga and Kama rivers confluence. In the morphological structure of bacteriobenthos, the main morphological group were bacilli, followed in importance by coccobacilli. The predominant size classes of bacteria were 0.2-0.5 μm, 0.5-1.0 μm, and 1.0-2.0 μm. A number of reliable correlations were obtained between the characteristics of bacteriobenthos and the grain-size composition of sediments, organic matter content, and humus content. The share of aleurite fraction, organic matter content, and humus content affect the trends in the spatial distribution of quantitative indicators of bacteria. Main morphological and size groups of bacteria were significantly related to certain size fractions of the mechanical composition of bottom sediments, which affects the spatial distribution of these groups along the bottom of the reservoir.