Nematodes of gobiids (Perciformes, Gobiidae) in Saratov reservoir

Provides information on the species composition of the fauna of nematodes and indicators of infection of three species of gobiids (fam. Gobiidae), are alien in Saratov reservoir. Gathering material was carried out in the waters of the Koltsovo-Mordovian area of the reservoir (the middle part) during the period 2009-2015. Catching fish was performed using with a float rod and hydrobiological net. Only the method of complete parasitological dissection was investigated 478 individuals of adult fish: 320 individuals of the round goby Neogobius melanostomus, 137 individuals of the bighead goby N. iljini and 21 individuals of the tubenose goby Proterorhinus semilunaris. 6 species of nematodes were found in the surveyed water area of the Saratov reservoir near bovine fish. Species composition each type is different: bighead goby infected 6 species of worms, the round goby was 4 species of nematodes, the tubenose goby infected only 1 species. The only common species is Contracaecum microcephalum larva, which dominates in abundance and occurrence in all fish species. The calves infected by this avian nematode occur through consumption of infected copepods, chironomids and dragonfly larvae, and juvenile fish. In conditions of the Saratov reservoir in goby fishes are the main second intermediate and reserver name owners in the development cycle of C. microcephalum. The incidence and average number of parasites in round goby and bighead goby throughout the period of research is maintained at a consistently high level. Bovine fish act as intermediate and / or reservoir hosts for two types of round worms (Eustrongylides excisus and Desmidocercella numidica). For 3 species of nematodes (Capillaria tomentosa, Camallanus lacustris and C. truncatus), the fish are the final (definitive) hosts in whose organism the parasites reach puberty. The formation of nematodofauna steers fam. Gobiidae in the Saratov reservoir occurred in accordance with the general laws identified by V. A. Dogel for fish-acclimatizants. Purchased the area from native fish there is a significant impoverishment of the composition of the parasites; however, the downward trend in species diversity of roundworms from the bighead goby to tubenose goby the saved. Simultaneously acquired local helminths species (widely distributed united palaearctic species). However, the introduction into the reservoir of alien fauna of parasites did not happen.