Albert Lillehammer

Stream Regulation in Norway

Norway, situated in northern Europe, is characterized by mountainous area in the north and west with relatively short and fast running streams, while in east and northeastern Norway the largest watercourses are found. Watercourses in Norway have been used for various purposes, such as timber transport, mills and sawmills, as well as drinking water. However, the greatest use is connected with the great demand for hydroelectric power, and this paper will consider mainly the effects of such regulation.

Stoneflies and River Regulation — A Review

Stoneflies (Plecoptera) are a widespread and abundant order of benthic freshwater insects, especially in the running waters of temperate regions. They occupy a central role in trophic relationships both in terms of functional feeding groups and as fish food organisms. Although recorded from a range of freshwater habitats, the greatest species diversity is to be found in cool lotic habitats (Hynes 1976; Baumann 1979). They are considered to be good indicators of water quality and environmental change (Gaufin 1973; Baumann 1979).

The Coexistence of Stoneflies in a Mountain Lake Outlet Biotope

The composition of the stonefly fauna, the growth phases of all the species and the food composition of the predatory species (Fam. Perlodidae) were studies in a lake outlet biotope at Valdresflya in the Jotunheimen mountains, in central southern Norway. The biotope, in a region with a subarctic or tundra macro-climate, is ice-covered from early October to late June. Five differen stonefly species were studied: Arcynopteryx compacta, o-Diura nanseni, hoperla obscura, Capnia atra and Amphinemura standfussi. The two herbivorous species, C. atra and A. standfussi have completely separate life-cycles. In contrast, the nymph stages of the three predatory species all occurred at the same time of the year, although separated by size during the growth period and with little real overlap in their food habits. All the three predatory species were omnivorous, eating plant detritus and algae at certain periods of the year.