Variability of life cycles of intestinal helmints Perca fluviatilis Linnaeus, 1758 (national park "Samarskaya Luka", Russian Federation)

The variability of life cycles of intestinal helminths Perca fluviatilis in the reservoirs of the National park «Samarskaya Luka» in the period of 1990-2016 was studied. Its increase in the last 10th anniversary was noted, due to the appearance of new aboriginal and alien parasites in the perch, a change in the composition of fish community, more active feeding on invading fish, and the establishment of close biotopic relationships with alien species (fish, molluscs). The data obtained reflect the characteristic features of the biotic relationships of Perca fluviatilis with individual invader species (parasites, mollusks, fish) and aboriginal species (parasites, zooplankton, fish). An expansion of the host range of aboriginal and alien parasites, further qualitative and quantitative changes in the structure of fish- and parasites of communities and correction of biotopic bonds of hydrobionts are predicted.