ダムが河川の底生動物へ与える影響 [in Japanese] Effects of dams on benthic animals in streams and rivers [in Japanese]
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Influences of dams on benthic animal communities in tailwater rivers were reviewed focused on changes in their species richness, population densities and biomass. It was commonly observed that the benthos communities below dams had more population densities of fewer numbers of taxa in comparison with control rivers without dam effects. However, not a few works reported different results such as a case of less species richness, less population densities and less biomass or a case of more species richness in benthos communities below reservoirs. We considered functional processes of dam effects on benthos communities in the following respects: i.e., 1) impacts of flow regime regulation including stabilization of water flow, frequent flow fluctuation by electric power station, and drought in an extreme case, 2) alteration of habitat structure such as stabilization of river bed, water courses and armoring, 3) alteration of thermal regimes derived from surface or deep waters of the reservoirs, 4) effects of siltation, 5) effects of increasing plankton supply from the reservoirs, and 6) effects of dams and reservoirs themselves as an obstacle for migration by adult aquatic insects. The importance of Serial Discontinuity Concept and its future perspectives were also discussed. In order to assess the influences of dam construction and its management properly, the SDC model should be modified to reflect individual characteristics of each river and to include influences on diadromous animals and estuarine ecosystems.
ECE 2(2), 153-164, 1999-11-19
Ecology and Civil Engineering Society