Ecological State of Aquatic Ecosystems of Ukraine Using the Dnipro River as an Example

Main causes of deterioration of the quality of the surface waters in Ukraine: the changes in hydrological and hydrochemical characteristics associated with flow over-regulation and increasing anthropogenic pollution, and, as a result, a change in the species composition of hydrobionts, are studied using the Dnipro river as an example. Analyzed are the factors which lead to the degrading quality of natural waters as a result of the mass reproduction of unicellular algae (algal blooms), primarily blue-green ones, which reduce the concentration of dissolved oxygen and cause mass mortality of aquatic animals, especially in winter.