Influence of water management in lowland region of the Dyje River on water biocoenoses

Abstract

This work contains the results of influence of water management in lowland region of the Dyje River on water biocenoses. Research was carried out in 1977–1984, when building of the three reservoirs were started. The effect of the newly built reservoirs on the biocoenoses of the reach immediately below it was mainly beneficial. Before the reservoir near Nové Mlýny was bulit, the fish population of the Dyje River was regularly threatened by poor water quality. After completion of the three reservoirs in 1989 the pollution brought by the Dyje River was largely removed by the purification processes in the reservoirs, so that the Dyje River became cleaner than it was. The better trophic conditions and water quality downstream of the reservoirs were reflected in increased fish catches and higher fish weights. The newly built fish passes make possible migration of rare fish species from the Danube River as far as to reservoirs the Nové Mlýny.

Keywords

• lowland of the Dyje River
• water management
• quantity of macrozoobenthos
• indices of saprobity