Ecology of the regulated river Storelva in western Norway 50 years after regulation

Abstract

The river Storelva, situated in Sauda, Rogaland in western Norway has been regulated for hydroelectric power since 1914 and about 80% of the water-flow is transferred through tunnels to the various power stations and then to the fjord. The river held a uniform benthic invertebrate fauna which was dominated numerically by chironomids and a few other groups, viz. the trichopteran Polycentropus flavomaculatus and the stoneflies Amphinemura sulcicollis and Leuctra fusca. The feeding groups collectors, both filterers and gatherers, and predators were strongly represented in this regulated river. The population of salmon was negligible and only low numbers of trout occurred. The young trout mainly fed on the chironomid larvae.

Keywords

• Insecta
• Diptera
• Plecoptera
• Trichoptera
• Actinopterygii
• Salmoniformes