The modern state of biota in the Kuma-Manych depression. Ust-Manychskoe, Veselovskoe, Proletarskoe, and Chograiskoe reservoirs (a review)

摘要

The main trends in the development of aquatic communities in reservoirs of the Kuma-Manych depression are considered. The ecosystem of Lake Manych-Gudilo is the most transformed as a result of the extinction of brackish flora and fauna against the background of increasing salinity. The structure of biota became simpler, and productivity decreased. The species diversity of plankton and benthos decreased considerably, and now it is represented by monodominant communities. A sharp reduction in the habitat areas of bottom and plankton organisms occurred. At present they inhabit biotopes with aquatic vegetation in desalinated mouth areas. In summer, destruction processes prevail over the productive, which affects the formation of organic matter and the concentration of nutrients in the water column. At present structural and functional characteristics of the aquatic ecosystem correspond to those before the period of the river regulation. Aquatic communities in the Veselovskoe reservoir and in the part of the Proletarskoe reservoir between dams are relatively stable despite the decrease in the volume of fresh water input, and their fish productivity is high. The restoration of the former productivity and fish resources in the Proletarskoe and Chograiskoe reservoirs is impossible without reconstruction of the soil-reclamation system and maintenance of a fresh water supply in the former volumes.