Changes in zooplankton communities of the Lebyazhye system restored lakes

Abstract

Ponds rehabilitation projects for the purpose of eco - rehabilitation following significant anthropogenic impacts or degradation are becoming more frequent but not always successful. Therefore, the experience of the restoration of the Lebyazhye system lakes in Kazan city (Russia) is interesting. Previously, the lake system used to consist of four ponds, but due to water catchment area reduction, the area of the lake system also decreased, and only one lake remained. The restoration of the Lebyazhye system lakes was carried out in 2017 and included the deepening of the basin of the Bolshoe and Svetloe Lebyazhye lakes to 4 m, the sealing of the bed of future ponds with bentonite mats, supplying water from Izumrudnoye lake through a pressure water conduit and filling the basin of the lakes with water. The research is devoted to the study of the restoration of zooplankton communities in the Lebyazhye system lakes. For this purpose, the indicators of zooplankton communities before and after eco-rehabilitation measures were compared. After the implementation of eco-rehabilitation measures, significant changes in environmental parameters were observed: the salinity of water decreased, the oxygen content in the water, pH increased. In zooplankton communities, the species richness and diversity increased, new species appeared, as well as those that lived in the lake system earlier before eco-rehabilitation measures were taken.