Influence of the Water Level in the Yenisei River on the Ecosystem of its Anabranch within the City of Krasnoyarsk

• Published in: Žurnal Sibirskogo federalʹnogo universiteta. Seriâ Biologiâ (Online) Vol. 16; no. 3; pp. 336 - 362
• Main Authors: Dubovskaya, Olga P, Kravchuk, Elena S, Ivanova, Elena A, Glushchenko, Larisa A, Shulepina, Svetlana P, Anishchenko, Olesya V, Tolomeev, Alexander P, Drobotov, Anton V, Morozova, Inna I, Perminova, Anzhelika S, Anishchenko, Yuliya D, Prokopkin, Igor G
• Format: Journal Article
• Language: Russian
• Published: Krasnoyarsk Siberian Federal University 01.07.2023
• Subjects: Abundance; Algae; Anthropogenic factors; Aquaculture; Aquatic ecosystems; Aquatic plants; Biomass; Biota; Dams; Decision making; Downstream; Eutrophication; Fish; Fish culture; Flooded soils; Habitat selection; Human influences; Hydroelectric plants; Hydroelectric power; Hydroelectric power plants; Inflow; Locations (working); Macrophytes; Nutrients; Organic matter; Outbreaks; Outlets; Parameter modification; Parameters; Phosphorus; Plankton; Primary production; Receiving waters; Recreation; Recreational waters; Reservoirs; Rivers; Soil microorganisms; Spirogyra; Storms; Warm water; Water bodies; Water levels; Water temperature; Zoobenthos; Zooplankton; Yenisei River
• ISSN: 1997-1389; 2313-5530

Located within the city of Krasnoyarsk, 35 km downstream of the Krasnoyarsk Hydropower Plant, the Abakanskaya anabranch of the Yenisei River, on the one hand, is an important recreational water body and, on the other hand, is subject to several types of anthropogenic impact (regulation by a dam, inflow of storm and warm waters, fish farming). These impacts worsen its recreational properties due to excessive growth of macrophytes and metaphytic filamentous algae of the genus Spirogyra, causing deterioration of organoleptic and microbiological parameters of water. Natural climatic factors can significantly modify the influence of anthropogenic factors, which is of interest in terms of forecasting and decision-making about the elimination of negative factors. The aim of the present work is to assess the influence of the water level regime of the Yenisei River in the spring-summer period on the anabranch ecosystem by comparing the data for the high-water (2021) and medium-water (2020) years. Hydrophysical, hydrochemical, and hydrobiological measurements were carried out from May to August 2020 and 2021 at locations on the left bank: 1 - upstream of the dam (reference), 2 - downstream of the dam, 3 - opposite the outlet of warm water, 4 - at the beach, downstream of the fish farm. In 2021, water entered the anabranch only from downstream (to locations 4 and 3), since the culverts in the dam body were filled up. In 2021, compared to 2020, the abundance and biomass of phyto- and zooplankton in the regulated section of the anabranch significantly increased, the primary production of plankton increased, but the corresponding parameters of phytoperiphyton and zoobenthos, on the contrary, decreased due to their formation on freshly flooded soils. Metaphyton was absent, but in August, Spirogyra began to dominate in the phytoperiphyton biomass. Nitrite ion concentrations in the water increased in the regulated part of the anabranch, and the nitrate ion and total phosphorus concentrations increased at all locations, including the reference location, receiving water from the Krasnoyarsk Reservoir. The plankton "abundance outbreak" observed in 2021 at locations 3 and 4 was caused by the water level in the anabranch remaining high over a long period (one and a half months), which made it possible for the biota to use organic matter and nutrients washed out from the flooded banks; the outbreak was similar to those occurring in the ecotone zones of inputs to the upper parts of reservoirs. The annual increase in the concentrations of mineral forms of nitrogen and total phosphorus at the lower locations compared with other locations was probably due to the eutrophic influence of fish farming.