ВПЛИВ ФУНКЦІОНУВАННЯ ЯВІРСЬКОЇ ГЕС НА УГРУПОВАННЯ БЕЗХРЕБЕТНИХ ГІДРОБІОНТІВ Р. СТРИЙ (УКРАЇНСЬКІ КАРПАТИ)

Abstract

The most negative impact of Yavirska HPP on the aquatic invertebrate communities of river Stryi is noted along four kilometers stretch below the dam. Taxonomic diversity, abundance and biomass of the communities on this part of the river decreases in two to three times compare to the sampling sites above Yavirske reservoir. At a distance over six kilometers below the dam structural parameters of the invertebrate groups are restored to the natural status (like the sampling sites above the reservoir). The number of individuals of the drift after passing through the reservoir and the dam decreases tenfold on average. Water of the investigated river stretch is slightly polluted (the sites, which are outside from the direct influence of the HPP functioning) and moderately polluted (the reservoir by it self and the sites located in the zone of HPP influence). The results of our investigations point out the main negative factors, that are as follows: limnethic conditions of the reservoir in the river continuum, accumulation of silt and clay sediments on the bottom and the banks of the reservoir, demolition of sediments in the lower stretch of the river, destruction of the river bottom substrate below the dam due to the rapid descent of large masses of water, instant shallowing of the Striy river bed below the dam after the closing of station sluice in June, and some hydro-ground works below the dam.