ダム構造物と魚類の生活 Dam and fish life-history-ecological perspectives in the environmental conservation

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著者

    • 森 誠一 MORI Seiichi
    • 岐阜経済大学経済学部生物学研究室 Biological Laboratory, Department of Economics, Gifu-keizai University

抄録

ダム構造物およびダム湖という湛水域は,環境の生物的・物理的な構成要素に影響を及ぼす.湛水域には堆砂が増加し,下流へ大量の濁水が,特に建設工事中や増水時に流出する.ダムの放水運用によって,河川水量は季節や一日の内で短期間に大きく変化する.こうした河川から湖への生態系の変化は必然的に,魚類相,魚類の餌生物相,個体群動態の変化を引き起こし,水産業にも打撃を与える.例えば,ダムは魚の上流や下流への移動を妨害し,魚類群集の変化がダム上・下流の広い範囲で認められた.湛水域は在来種の産卵場所を消失させ,個体数の激減を導く.また,湛水域に放流された移入魚の増加は,在来種の絶滅と関連することもある.こうしたダム構造物や湛水域,水量管理による魚類への多くの不利な影響とその改善策を,水域の環境復元のための将来計画を立てる上で十分に考慮調査されなければならない.今後,長期の持続的な生態学的評価に基づいて,ダム除去を含む河川生態系改善のためのシナリオを作成することが切望される.

Damming causes many changes to the river. A dam and the resultant man -made lake change the river environment through a complex web of biological and physical impacts. The change from the river ecosystem to the lake ecosystem at the dam site will inevitably result in alteration of species composition, food habits and population dynamics of fishes. River impoundment affects endemic fish fauna and their life-histories through the following mechanisms : i. e., transverse blocking of the river channel, alteration of flow regimes and thermal regimes, and hindering upstream and downstream migration. Changes in fish communities have been recorded within considerable distances both upstream and downstream of dams. Hydropower reservoirs suffer high mortality if fish pass through the turbines. Since reservoir becomes a sink for sediments, seston transport is dramatically affected. Turbidity will increase during the construction phase and often over long distances. These constraints may lead to catastrophic falls in the abundance or extinction of some fish populations. The extinction might be associated with the introduction of exotic species. Flow regulation by dam can prevent or delay the inundation of floodplains and riparian zones, reducing or eliminating areas for breeding and reprodution of fish. These rapid and often extensive changes in the discharge regime cause displacement of fish, particular-ly juveniles, and can lead to loss of the fisheries. The modification of seasonal and diurnal thermal regulation causing the alteration of fish assemblages, usually results in reduction of species diversity in the river, when the dam releases the hypolimnial and/or epilimnial waters. The numerous unfavorable effects of impoundments and other forms of river regulation must be well documented for the planning and execution of future projects for the rehabilitation of water courses. Ecological evaluation is essential part of the programme on the base of "long-term environmental sustainability". It is hoped that the principles and guidelines of habitat improvement including the idea of removing dams will be made based on long-term ecological assessment.

収録刊行物

  • 応用生態工学 = Ecology and civil engineering  

    応用生態工学 = Ecology and civil engineering 2(2), 165-177, 1999-11-19 

    Ecology and Civil Engineering Society

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各種コード

  • NII論文ID(NAID)
    10021975992
  • NII書誌ID(NCID)
    AA11528360
  • 本文言語コード
    JPN
  • 資料種別
    REV
  • 雑誌種別
    大学紀要
  • ISSN
    13443755
  • NDL 記事登録ID
    4955269
  • NDL 雑誌分類
    ZN1(科学技術--建設工学・建設業) // ZR1(科学技術--生物学)
  • NDL 請求記号
    Z74-B482
  • データ提供元
    CJP書誌  CJP引用  NDL  J-STAGE 
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