Assessment of the state of Lake Maloe Lebyazhye (Kazan, Russia), based on zooplankton, for the purpose of eco-rehabilitation

Abstract

The work is devoted to the study of zooplankton community structure of Lake Maloe Lebyazhye (Kazan, Russia). Previously, Lake Lebyazhye consisted of 4 lakes, connected by ducts. Over the past decades, there has been a significant reduction in the area of lake, and only the Maloe Lebyazhye has remained. Other lakes of this system dried up. Methods: In 2017, measures were taken to restore the lakes of Bolshoe and Svetloe Lebyazhye: They were deepened to 3 m; the bottom was insulated with bentonitic mats. In October 2017, the lakes were filled with water. For the implementation of water supply, the pressure water conduit was restored to supply water from the nearby Lake Izumrudnoe. The study of the zooplankton community of Lake Maloe Lebyazhye is relevant and necessary to identify changes, occurring after the completion of measures for eco-rehabilitation. Results and Discussion: The article presents the results of studies of the zooplankton community of Lake Maloe Lebyazhye, performed during the growing periods of 2015–2017. In the course of the research, current species composition of zooplankton was revealed, the abundance and biomass were estimated, and the biotic indices were calculated. Conclusions: It is revealed that the zooplankton of the lake is represented by 64 species. The mean values of the abundance and biomass of zooplankton are relatively low and are in the range of values, corresponding to the oligotrophic type of water body.