小浪底水库排沙对黄河鲤鱼的急性胁迫

为探讨黄河小浪底水库排沙过程中出现"流鱼"现象的原因,在水库排沙开始前和过程中以黄河鲤鱼为对象进行了生理生态观测。结果显示,相对于对照组,排沙组的黄河鲤鱼消化道充塞系数显著下降(P<0.001),消化道内容物含沙质量比率显著上升(P<0.001);肝脏总抗氧化能力显著上升(P=0.036),而脾脏总抗氧化能力显著下降(P=0.017);肝过氧化氢酶CAT活性显著上升(P=0.035);肾脏超氧化物歧化酶SOD活性显著下降(P=0.038);肝脏、脾脏丙二醛MDA含量显著下降(肝脏:P=0.039;脾脏:P=0.027);鳃丝钠钾ATP酶活性显著下降(P=0.001);血清乳酸LD含量显著上升(P=0.019);肝脏乳酸脱氢酶LDH活性显著下降(P=0.001);推测高含沙水流对黄河鲤鱼造成的急性缺氧应激是导致小浪底水库排沙过程中"流鱼"现象的主要原因之一。

Acute stress caused by sand discharging on Yellow River Carp (Cyprinus carpio) in Xiaolangdi Reservoir

The Xiaolangdi reservoir is one of the biggest reservoirs on the Yellow River which plays a very important role in regulating the environment about the river.Because the riverbed downstream is getting higher and higher with time elapses,special Sediment-Flushing-Process has to be taken annually since 2002.During this process,however,there are usually large-scale of "flowing fish" in Yellow River which has been ignored by the authority for some time already.Based on the related reports and our pre-investigation,Yellow River Carp Cyprinus carpio,which is one of the most important commercial fish in Yellow River,is one of the main species that suffers from the process.In order to investigate the internal causations of the "flowing fish" phenomena,we collected 6 samples for the control group((872.9±59.97) g,Mean±SD) before the process and 6 samples for the experimental group((765.7±93.37) g) during the process.The sampling location was on the shore 3km downstream to the Dam.All the 12 fish was killed immediately after collection and dissected on the spot,some physical index such as the length and the weight were measured,and the alimentary canal was fixed in the alcohol(95% v/v).In addition,the plasma and some related organs(liver,spleen,kidney and gill) were put into the liquid nitrogen and then were transported back to our laboratory and kept in the low-temperature refrigerator with the temperature-80℃.After that,the physiological changes of C.carpio during the sediment flushing process were determined in the laboratory.Comparing with the control group that was collected before the sand discharging,fish collected during the process of the sediment flushing showed significant physiological changes: their gastrointestinal filling index was significantly lower(P<0.001),while the proportion of sand weight in the alimentary canal was much higher(P<0.001);Hepatic total antioxidant capacity(T-AOC)(P=0.036) and catalase(CAT)(P=0.035) activity were significantly higher,but T-AOC activity in spleen(P=0.017) and superoxide dismutase(SOD) activity in kidney were significantly lower(P=0.038);Malonaldehyde(MDA) content in liver(P=0.039) and spleen(P=0.027) were significantly lower.For the experimental fish,the activity of Na+/K+ATP enzyme in gill was markedly lower(P=0.001),while the content of lactic acid(LD) in serum was much higher(P=0.019) and the activity of lactate dehydrogenase(LDH) in liver was significantly lower(P=0.001).Therefore,the acute hypoxia caused by the rapid flowing water with high sediment concentration may be one of the dominant reasons for "flowing fish" during the sediment flushing process in Xiaolangdi reservoir.To the best of our knowledge,this was the first report to evaluate the acute stress effects on fish during the process of sediment flushing in reservoir.It is a correct decision that this method of regulating the river has been taken into effect and has been contributing to the environment.What we propose is that some index about this process such as the sand content should be paid more attention.So that the environment in the river could be keep balanced while the process itself could also play the important role about sand discharging efficiently and smoothly.