[Fish parasites as bioindicators of the pollution of bodies of water].

The paper presents the results of studies on the effect of wastes of the Cherepovets iron-and-steel works containing phenol, naphthaline and oil products on fish parasites of the Sheksna part of the Rybinsk water reservoir (the Volga river system). It has been shown that the number of highly sensitive ectoparasites of Abramis brama (Protozoa, Dactylogyrus monogeneans, Ergasilus sieboldi crustaceans and Caspiobdella fadejewi leeches) considerably decreases in the zone of pollution. It has been first suggested to use Diplozoon paradoxum and Caryophyllaeus laticeps, parasites of bream highly resistant to toxic effect, the number of which considerably increases in the zone of pollution, as indicators of anthropogenic pollution and ecological state of a water body. Among diplozoons there have been first discovered individuals having structural anomalies (reduction of the attachment organs, violation in the symmetry of arrangement and number of valves) that serves as evidence of mutagenic effect of toxic substances of polluted waters on morphogenesis of the parasite.