The State and Structure of Macrozoobenthos Communities of the Usman River according to the Materials of the 2021 Expeditionary Survey

Abstract

Background: For small rivers, the monitoring carried out by the Center for Hygiene and Epidemiology in the Voronezh Region is insufficient due to the limited number of water sampling points and the assessment of its quality only by a number of priority chemical and microbiological indicators. Objective: To assess the state and structure of macrozoobenthos communities of the Usman River affected by local anthropogenic contamination. Materials and methods: The analysis of the river water quality included testing of safety and chemical indicators by laboratory research methods. Surveys of the macrozoobenthos of the river were conducted as part of the research expedition in September–October 2021. The dominant information structure of bottom communities from the upper reaches to the mouth of the river was analyzed, after low water and pollution of the upper reaches of the river by industrial and household effluents in the 2020/2021 winter period. We established the main types of communities, identified dominant species, and analyzed indicators of the information structure. Results: Our findings confirm a strong destructive effect of organic discharges of “Ovoschi Chernozemya” LLC [Vegetables of the Black Earth Region] and “Vodokanal” wastewater service of the town of Usman on the bottom communities of the river, where, in comparison with the background, near the village of Krasnoe, we observed a change of community types and a multiple decrease in species diversity, abundance, biomass, stability, suppression of information diversity, and “jump” in entropy, indicating either degradation or a period of community restructuring.