Bigun V. The invasion fish species and their impact on the aboriginal fish fauna of the river-lake network of the Western Polissya of Ukraine

The thesis is devoted to the determination of impact of the invasive fish species on aboriginal fish fauna of the river-lake network of the Western Polissya of Ukraine. The work deals with results of the integrated studies of the species composition and structure of the fish fauna of the river-lake network structure of Western Polissya of Ukraine. Five invasive fish species were revealed in the region for the first time. The species diversity variety and quantity of rare aboriginal fishes was stated, list of the regional rare fishes was compiled. Rate of similarity of the fish communities of the different-type aquatic ecosystems using the Serensen coefficient and communities' typicalness by species composition was stated. Field studies on the invasive fish species feeding were combined with similar experiments in laboratory; in course of these studies selectivity of the invasive fishes feeding by the aboriginal fishes spawn was investigated. New data were obtained regarding ecological and biological peculiarities of the invasive fish species; were stated main biotopes and distribution peculiarities, ecological role of the invasive fishes was determined and their impact on aboriginal ichthyofauna of the considered region was analyzed. Methodology of control on the invasion process was developed, perspectives of use of the invasive fish species was assessed, measures to mitigate negative role of their populations were developed and suggestions in a legislative aspect were given