Assessment of Ecological Processes in the Sviyaga River (Ulyanovsk Region)

The Sviyaga River is a water resource, and a recreational facility. It is rich in fish, therefore the assessment of ecological processes in the Sviyaga river is relevant and has theoretical and practical significance. The relevance and practical significance of research is increasing due to the plans to use the Sviyaga river bays for aquaculture development. The purpose of the study was to examine the nature and direction of ecological processes in the Sviyaga River bays on the territory of the Ulyanovsk region. Materials and Methods. The assessment of the bay water quality was carried out according to organoleptic, hydrochemical and hydrobiological parameters. Results. Organoleptic water parameters in both bays met the requirements for natural waters. The maximum water temperature in summer reached 24–26 ºС, the average temperature was 20.5 ºС. The amount of dissolved oxygen (6.5 mg/l) corresponded to the optimal values for the life of many fish species, and pH level showed weak water alkalinity. Hydrochemical bay water composition indicated high organic pollution. In both bays, and in the Sviyaga river itself, the content of heavy metals and petroleum products was several times higher than the threshold limit value. BOD5 level in the bays significantly exceeded the limit values. BOD20 and chemical oxygen demand exceeded the standards four times. The results of a microbiological study revealed significant water contamination with Escherichia coli. The species composition of the aquatic phytocenosis in both bays largely corresponded to the Sviyaga River phytocenosis structure. However, the bays are characterized by plant species and ecological processes that indicate the initial stages of their waterlogging.