Materials on multicellular parasites fauna of the ruffe Gymnocephalus cernuus Linnaeus, 1758 (Pisces: Percidae) from the Saratov water basin.
Objective of research. Data on the species composition of the fauna of multicellular parasites and the infection rates of the pope ruffe Gymnocephalus cernuus Linnaeus, 1758 from Mordovian floodplain of the Saratov reservoir (the middle part) are presented. Materials and methods. 53 ruffe individuals were investigated in spring and summer 2012-2015 by incomplete parasitological post-mortem examination (Bykhovskaya-Pavlovskaya, 1985). 19 species of multicellular parasites belonging to 7 classes: Monogenea - 1, Cestoda - 1, Trematoda - 11, Nematoda - 3, Acanthocephala - 1, Bivalvia - 1, Crustacea - 1 were registered. The largest group are flukes; more than half of species (8) are larval forms, which is the result of bottom living of the host. The significant diversity of larval stages of helminths (8 species of trematodes and 2 species of nematodes) shows the involvement of the ruffe as an intercalary, supplementary and/or reservoir host in the circulation of parasites in fish, birds and mammals. 7 species of parasites infest the ruffe on the food chain; 12 species - using the active infestation way. Results and discussion. The studied parasite fauna contains one species narrowly specific for the ruffe (monogenea D. amphibothrium (Wagener, 1857)) and 2 species typical for percoid fishes (cestoda Proteocephalus percae (Müller, 1780) and trematoda Bunodera luciopercae (Müller, 1776)). 2 alien species Nicolla skrjabini (Iwanitzky, 1928) (marita) and Apophallus muehlingi (Jägerskiöld, 1898) (mtc.) whose natural habitat is limited by the rivers of the Azov-Black Sea and Baltic Sea were registered in the fauna of multicellular parasites of the ruffe from the Saratov reservoir. The most common ruffe parasites are Diplostomum and Ichthyocotylurus metacercariae metacercaria infesting fish by penetrating through the body covers. These metacercariae as well as Apophallus muehlingi metacercariae are pathogenic to fish.