鱼类在TDG过饱和含沙水体中的耐受性

为探讨高坝泄洪引起的总溶解气体(TDG)过饱和含沙水体对鱼类的影响,以岩原鲤和鲢鱼为研究对象,开展TDG过饱和含沙水体对不同鱼类的急性暴露试验,根据鱼类受TDG过饱和含沙水体胁迫后的异常行为和死亡率、半致死时间等指标来分析不同鱼类受胁迫后的耐受性和差异性。试验结果表明:试验初期,试验用鱼出现较明显异常行为和气泡病症状,且岩原鲤早于鲢鱼;相同TDG饱和度下,随着含沙量的增加,试验用鱼半致死时间缩短,且岩原鲤半致死时间短于鲢鱼,表明鲢鱼比岩原鲤具有更强的适应能力和耐受能力;当TDG饱和度较高时,即使含沙量低,也会造成试验用鱼的大量死亡;过饱和TDG是导致试验用鱼死亡的主要原因,但不能忽略泥沙对试验用鱼死亡的促进作用。

Tolerance of fish to TDG supersaturated water with sediments

To investigate the impacts of the total dissolved gas(TDG)supersaturated water with sediments on fish due to flood discharge from high dams, rock carp(Procypris rabaudi Tchang)and chub(Hypophthalmictuthys molitrix)were chosen as test objects and acute exposure experiments were performed to investigate the effects of TDG supersaturated water on different species. Tolerance and difference were analyzed based on the indexes of abnormal behavior, death rate, and median lethal time of the fish. The experimental results show that abnormal behaviors and symptoms of bubble disease are obvious on the test fish during the initial stage of the experiment and the abnormity was found firstly on rock carp. Under the same TDG supersaturated water condition, increase of sediment concentration can lead to a decreased median lethal time for both rock carp and chub, but the latter has longer median lethal time, revealing that chub has much stronger adaptability and endurance capacity. Moreover, when TDG supersaturation level remains a high value, even low sediment concentration can cause a high mortality of fish. TDG supersaturation level is the major reason for fish death, but the acceleration effects from sediment cannot be ignored.