Changes in the structure of fish assemblages in a river used for energy production

Abstract

The fishes in the River Jihlava (a tributary of the River Svratka, Danube drainage basin, Czech Republic) have been monitored over the past 26 years. The objective of this monitoring has been to determine the effects of the construction and operation of an energy operating complex. This complex is composed of two hydroenergetic reservoirs at Dalešice and Mohelno (completed in 1977) and an adjacent nuclear power plant at Dukovany (power generation started in 1985), water is pumped from the reservoir at Mohelno to supply cooling water for the nuclear power plant. The operation of this combined hydro and nuclear power system has led to substantial changes in the morphological, hydrological, hydrochemical and hydrobiological characteristics of the former riverine habitats. These habitat changes have been followed by considerable changes in the composition of the fish assemblage. In the river downstream of the reservoirs, the former fish community, which was dominated by the barbel (Barbus barbus), has been replaced by a trout (Salmo trutta m. fario) community. In the Dalešice reservoir, limnophilic species generally replaced rheophilic species. Both of these habitats are now highly valued for their sport fisheries. Copyright © 1999 John Wiley & Sons, Ltd.