The influence of changes of the hydrological regime on the formation of macrozoobenthos communities of the SouthernBuh within the village of Myhia
The article presents the role of the elements of the hydrological regime in the formation of the benthos fauna of shallow water areas of the plain rivers. Studies have shown an increase in flow in the channel network can in a relatively short period of time lead to the reshaping of the species composition of macrozoobenthos at low depths. It was found that the intensification of the water exchange process contributes to the overall improvement of water quality in shallow watercourses and increase the location and quantitative indicators of rheophilic and oxyphilic species of macrozoobenthos. Also, it was found that the resumption of operation of Mygiivska HPP in 2017 primarily led to a redistribution of water consumption in the water system of the Southern Bug near the village. Migiya. Thus, according to the results of comparison of water flow distribution schemes in July 2017 and 2018 in the area above the dam, water consumption increased in the area of the left side, the central part of the reservoir and in the lower reaches of the HPP. The main biotic component of the aquatic ecosystem of the studied area of the Southern Bug, which underwent significant changes after the commissioning of the Mygiivska HPP, was macrozoobenthos. After the commissioning of Mygiivska HPP, rheophilic and oxyphilic species became more widespread, and the areas occupied by V. viviparus and Th. fluviatilis. Comparison of data on water quality for 2 years showed that in 2018 in almost all surveyed areas water quality has improved. This is especially noticeable in areas of the river below the dam. According to the saprobity index, the class and category of water quality by the degree of pollution decreased by one and two units in the direction of improvement.
Studies of macrozoobenthos confirm that the reform of water flow and velocities, changes in the distribution of bottom sediments in the Southern Bug within the village. Mygia caused by the restoration of Mygiivska HPP became a positive factor in the functioning of the aquatic ecosystem of the study area. A more even distribution of water consumption in the water system not only helped to reduce the capacity of silt deposits in the most stagnant areas of the water area, but also had a positive effect on the state of benthic invertebrates and led to an increase in rheophilic and oxyphilic species.