Ichthyofauna species diversity in multipurpose water bodies of the forest-steppe zone of Ukraine by river basins

Purpose. To investigate fish fauna of multipurpose water bodies in the Forest-Steppe Zone of Ukraine in the basin of two rivers: South Bug (South Bug, Gnylyi Tikich), Dnipro (Dnipro, Ros, Desna rivers). To select equal water bodies based on their areas and degree of location relative to their main basin and compare these water bodies based on their similarity and typicality. Methodology. The collection of materials was carried out during 2010-2017 in multipurpose water bodies located in the forest-steppe zone of Ukraine in the basins of large rivers such as the Dnipro and the Southern Bug. Samples were taken along the Dnieper immediately below the basin of the Ros River, which flows into the Kremenchuk Reservoir on the Dnieper. As far as the Southern Bug, the samplings were not conducted below the Hlybochok HPP. Control catches were carried out with gill nets with mesh sizes of 40-80 mm, as well as with a 25-m-long fry beach seine with a mesh of 10 mm. Collection and processing of ichthyological materials was carried out according to generally accepted methods. When determining the impact of recreational and sports fishing, direct counting was used, which was carried out by means of route visits to the places of accumulation of recreational fishermen and their surveys. The Serenson’s similarity index was used to analyze the degree of similarity of ichthyofauna groups of water bodies: S = 2 С/А+В, where А — number of species in the first community, В — number of species in the second community, С — number of species common to both communities The typicality of ichthyofauna cimmunities by species richness was determined by the formula proposed by Shannon-Weaver: Rs=ni/N, where ni — number of species for the studied area, N — total number of species for the region. MS Excel was used for processing the obtained results. Findings. The fish fauna of the studied water bodies of the forest-steppe zone during the study period was not large enough in terms of species. A zonal distribution of fish fauna was observed in different rivers’ reaches, with a gradual decrease of native species towards invaders and acclimatizers, due to their constant stocking of multipurpose water bodies. This was especially observed on the Gnylyi Tikich River. Practical value. The similarity and typicality indices of river ecosystems were the most similar in this case of the Ros and Desna rivers, it is completely natural and highly probable. Therefore, it is necessary to continue researching rivers, and to carry out measures to reacclimatize native species typical for this region, especially commercially valuable species.