Current natural and anthropogenic threats to ecological well-being of freshwater ecosystems

The hydroecological situation on many water bodies on the territory of Ukraine has significantly deteriorated in recent decades, resulting in imbalances in hydroecosystems, deterioration of water quality, reduction of fish diversity and degradation of its physiological condition. In the light of the growing anthropogenic pressure on the environment, it is especially important to study the current state of water bodies to maintain ecological balance and ensure the sustainability of their use and to develop the water protection strategies. In order to comprehensively assess the ecological situation on water bodies of Ukraine for effective management of water protection activities on the example of the Ros river, the current state of the river basin, its hydrochemical characteristics over the past 28 years have been analyzed, the dynamics of average annual air temperature in the region has been studied, the water quality indicators by ecological and hygienic criteria have been calculated. The losses caused to fisheries during the mass slaughter of fish in August 2018 have been calculated. It is shown that both natural (climate change) and anthropogenic (high river control, specific features of the Stebliv Reservoir dam, high plowing of the river basin, systematic entry of pollutants into the aquatic environment from municipal and industrial enterprises and wastewater from agricultural lands) factors are the main reasons for the transformation of the aquatic ecosystem. For the first time, the ecological risk of affecting the well-being of the aquatic ecosystem of the Ros river has been assessed for the long term and it has been shown that the river water quality is unsatisfactory and there is a high risk of further degradation of the hydroecosystem. The greatest potential ecological risk of affecting the ecological well-being in the Ros river, reducing biodiversity and simplifying the trophic structure, comes from nitrogen compounds and polyphosphates. It is necessary to develop an adequate and reliable management strategy for the integrated use of water resources and implementation of proactive measures to minimize the risks of transformation of rivers hydroecosystems, which will contribute to their revival, environmental well-being and conservation of aquatic organisms biodiversity

surface waters; rivers transformation; ecological index of water quality; pollution index; potential ecological risk