Effects of hydropower development on aquatic macrophytes in norwegian rivers: Present state of knowledge and some case studies

Abstract

AbstractA multitude of Norwegian rivers are managed for generating hydroelectric power (HEP). The hydrology of these hydrorivers changes in various ways which reflect the implemented HEP schemes. Increased winter flows and a concomitant lack of ice‐cover are features found downstream of power installations on many Norwegian hydrorivers.Our study objectives were (1) to assess the changes in aquatic macrophyte abundance subsequent to HEP development; and (2) to evaluate the environmental conditions under which nuisance growths of macrophytes are likely to occur. Towards these ends, Norwegian literature data were compiled and assessed. Some case studies are outlined showing the variety of situations under which prolific growths of macrophytes might result. Unfortunately, available data on macrophyte‐associated problems proved deficient in many respects. This occurred chiefly because most macrophyte studies are conducted either before, or after, an HEP scheme is completed. Evidently, no concerted efforts are made for assessing the likelihood of macrophyte‐dominated nuisance growth in the planning stage of a Norwegian HEP scheme.