| Abstract: | It is shown for the first time that during 50 years of the Rybinsk reservoir's existence the abundance of parasite leeches (Piscicolidae) has increased, and the species composition has become richer. In 70 the leech Caspiobdella fadejewi (Epstein) was registered here as a mass species. This species became a real competitor to Piscicola geometra (L.) inhabiting the Volga river in all times. In early '90s the leech Acipenserobdella volgensis (Zykoff) appeared in the Rybinsk reservoir. Till 1987 this species was not found to the north from the Kuibyschev reservoir. An increase in number of fish leeches and an extension of their specific composition occurred not only in the Rybinsk reservoir but in the other reservoirs of the Volga cascade as well. |
