Assessment of an ecological state of the Kuibyshev reservoir based on zoobenthos indicators

On the basis of the analysis of long-term data of chemical and biological monitoring, the ecological state of the Kuibyshev reservoir (the Republic of Tatarstan, Russia) was defined. There were used the dissolved oxygen, BOD, ammonium content and pollutants with excess of maximum allowable concentration (15 ingredients in total) as markers of chemical pollution. Total number of a zoobenthos and relative number of oligochaetes were chosen as biological indicators. Based on chemical and biological indicators it was noted that the lower sites of the Kuibyshev reservoir are less polluted in comparison with top sites which ecosystem now is in transition state from equilibrium to crisis. (paper)