Small rivers of urbanized territories as an environment of ichthyocenosis

Purpose. Establishing the ecological potential of water bodies of various types in the composition of small rivers of urbanized territories based on their ichthyocenosis structure features, hydrochemical and toxicological indices. Methodology. The objects of the study were ichthyofauna species as well as water and bottom sediments. Materials were collected during 2015-2016 on the sections of the Gorenka, Lybid, Nyvka and Syrets rivers within the city of Kyiv. Collection of ichthyological material was carried out with a hand net, without the use of tools and methods that are in conflict with the law or need special permission. Processing of samples was carried out in accordance with generally accepted methods. Findings. It has been shown that the qualitative composition of ichthycenoses of small rivers depends on their hydromorphological and hydrological characteristics. According to the ichthyotcenoses structure, the highest ecological potential was inherent to waterbodies, where the connection with the receiving reservoir was maintained. The dominant complex in the ichthyotcenoses of such water bodies were native fish species indifferent to water flow velocity, which perform seasonal migrations, whereas mainly short-cycle limnophilic species including invasive ones were presented in isolated hydrostructures of water bodies. The water quality assessment based on hydrochemical and toxicological indicators also revealed the effect of the anthropogenic transformation of water bodies on their ecological potential. Thus, higher contamination and degree of water toxicity were inherent to more transformed watercourses. Originality. It has been established that in the case of small rivers within the boundaries of Kyiv, ecological potential of water bodies based on their ichthyofauna structure depended more on the preservation of their connectivity with the receiving reservoir and water flow rate than on hydrochemical and toxicological characteristics. Practical value. The study results can be used to develop measures aimed at preserving and restoring small river ecosystems, in particular their ichthyocenoses.