貧酸素時における底生魚チチブの水面近傍の空隙利用に関する実験的研究  [in Japanese] AN EXPERIMENTAL STUDY ON THE USAGE OF INTERSTITIAL SPACES NEAR THE WATER SURFACE BY <i>Tridentiger obscurus</i> IN A HYPOXIC ENVIRONMENT  [in Japanese]

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Abstract

尼崎運河は,矢板護岸に囲まれ,年間の大半で貧酸素化した状態にあり,生物の生息場としては大変厳しい環境にある.著者らは,運河の環境修復の方法として,貧酸素化されにくい水面付近に空隙のある構造物を設け,生物生息場としての運河の機能を高めることを考えた.本研究では,まず,尼崎運河で優占する底生魚チチブを用い,溶存酸素,明暗,空隙の設置水深といった条件を種々に変えた室内実験を行い,チチブの行動を観察した.その結果,チチブは,明暗で行動に違いがあることが定量的にわかった.またいずれの条件においても空隙を強く選好し,底層が貧酸素化した時には,水面近傍の空隙に長時間滞在した.他にも,空隙は貧酸素化のストレスを緩和するように作用することも示唆された.

 Surrounded by upright sheet-pile walls, the Amagasaki Canal is in a hypoxic state for over half of a year, making it an extremely severe environment for the survival of aquatic organisms. As a measure to restore the canal environment, we conceived of installing a structure with interstitial spaces near the water surface where the water is less affected by hypoxia, thereby, enhancing the canal functions as a habitat for aquatic organisms. In this study, we used <i>Tridentiger obscurus</i>, a demersal fish that is predominant in the Amagasaki Canal. We performed laboratory experiments under different dissolved oxygen levels, light conditions and installation position of the interstitial space and observed the behavior of <i>Tridentiger obscurus</i>. Our results showed that these fish changed their behavior depending on the light conditions. They also showed a strong preference for the interstitial space under all tested condition. When the bottom layer of the canal was deoxidized, they stayed around the interstitial space near the water surface. The interstitial space was also suggested to reduce the stress due to hypoxic conditions.

Journal

  • Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering)

    Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering) 74(2), I_498-I_503, 2018

    Japan Society of Civil Engineers

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