Dynamics of species diversity of Cyclostomata and fishes in the Kuybyshev Reservoir

For the first time, the precise species composition of Cyclostomata and fishes of the Kuybyshev Reservoir is presented at various phases of formation of its ecosystem. Special traits and tendencies of distribution of alien species in it are analyzed. The greatest changes occurred at the first phase. During subsequent phases, the species composition was supplemented mainly due to penetration of southern short-lived alien species with fractional spawning which successfully withstand the increasing anthropogenous impact. Penetration of alien species did not entail disappearance of aboriginal species as the colonizers occupied new limnophilic biotopes not demanded by the aboriginal ichthyofauna.