总溶解气体过饱和对胭脂鱼耐受性和回避性的影响现场试验

为真实反映水电工程天然河道中总溶解气体(Total Dissolved Gas, TDG)过饱和对鱼类影响的实际情况,选用胭脂鱼幼鱼和成鱼作为研究对象,开展大坝泄洪期间总溶解气体过饱和对鱼类影响的现场暴露试验,探究不同水深条件下鱼类对总溶解气体过饱和的水体耐受性和回避特性。结果表明:天然河道中,TDG饱和度为115%~117%时,胭脂鱼幼鱼在0~0.3,0.3~1.3,1.3~2.3,0~2.3 m 4个水层死亡率分别为42.5%,30%,7.5%,15%;低TDG饱和度水体也可导致胭脂鱼幼鱼死亡。但随着水深的增加,死亡率呈明显下降趋势,说明补偿水深能有效缓解TDG过饱和水体对胭脂鱼幼鱼的伤害。此外,研究结果也表明胭脂鱼幼鱼具有利用补偿水深来回避TDG过饱和伤害的能力;而胭脂鱼成鱼利用补偿水深逃避TDG过饱和伤害的行为并不明显。研究结果可为鱼类保护措施的制定提供参考依据。

Field Exposure Experiment on Tolerance and Avoidance of Myxocyprinus asiaticus to Total Dissolved Gas Supersaturation

Field exposure experiment was carried out to explore the tolerance and avoidance characteristics of Myxocyprinus asiaticus (Chinese high fin banded shark) to TDG supersaturated water under different water depths during flood discharge. The mortality of Myxocyprinus asiaticus was 42.5%, 30%, 17.5%, and 15% respectively when water depth was 0~0.3, 0.3~1.3, 1.3~2.3, and 0~2.3 m in natural river course downstream of dam with a TDG of 115%~117%. A low TDG level could also lead to the death of juvenile Myxocyprinus asiaticus. Nevertheless, increased water depth notably reduced the mortality of the juveniles, indicating that the depth compensation could effectively alleviate the damage of TDG-supersaturated water to juvenile Myxocyprinus asiaticus. In addition, juvenile Myxocyprinus asiaticus boasts an ability of avoiding the damage cause by supersaturated TDG with the help of water depth compensation while adult Myxocyprinus asiaticus has no obvious such behaviors. The research results offer a reference for the formulation of protection measures on fish.