总溶解气体过饱和与泥沙共同作用对长江上游特有鱼类的影响机制及规律研究

Gas bubble disease in fish and the death are easily found in the downstream river of dam during the flood discharge. This has been treated as an important ecological risk in the hydraulic engineering operation. In general, there are excessive suspended sediment and high total dissolved gas (TDG) supersaturation level in the downstream water of dam while the flood discharge occurs. The effect of TDG supersaturation on fish has been investigated widely in the world so far, however the achievements are quite lack on combined effect of TDG supersaturation and sediment on fish. In present study, Chinese sucker and rock carp dwelling in the upper Yangtze River are chosen as the study object and experimental studies of chronic and acute exposure to TDG supersaturation and sediment are conducted in the laboratory. Tolerance and adaptability of the different developmental stages fish will be investigated based on basic theory and methods of biology, ethology and morphology.The important influencing factor will be indentified on the tolerance and adaptability. The mechanism of combined effect of TDG supersaturation and sediment can be revealed on the illness and death of fish. Furthermore, field experiment are carried out on combined effect of TDG supersaturation and sediment in fish. The mechanism and rules of combined effect of TDG supersaturation and sediment on fish can be illustrated based on the laboratory study and the field experiment during the flood discharging. The results of study can provide a scientific basis to evaluate quantificationally the effect caused by flood discharge. It has a significant practical value to establish fish protection scheme.

大坝泄洪期间，常发生下游河道鱼类患气泡病甚至大量死亡的现象，成为水电工程运行的一项重大生态风险。大坝泄洪水体具有泥沙浓度高且总溶解气体（TDG）过饱和的特点。国内外对TDG过饱和水体的鱼类影响开展了较为系统的研究，但针对泥沙与过饱和TDG共同作用对鱼类影响的研究成果却严重匮乏。本项目拟以长江上游特有鱼类胭脂鱼和岩原鲤为研究对象，采用生物学、行为学和形态学的基本理论和方法，开展室内受控条件下鱼类受泥沙与过饱和TDG共同作用的急、慢性暴露实验，探究不同生长阶段实验鱼受过饱和TDG与泥沙共同胁迫影响的耐受性与适应性，辨识主要影响因素，揭示鱼类患病和致死的机理；开展工程泄洪期间鱼类受泥沙与过饱和TDG共同作用的现场暴露实验，通过与室内实验成果的对比分析，揭示过饱和TDG与泥沙共同作用对鱼类影响的机制。研究成果可为定量评价水电工程泄洪对鱼类的影响提供科学依据，对鱼类保护方案的制定具有重要实用价值。

大坝泄洪水体具有泥沙浓度高且总溶解气体（TDG）过饱和的特点，水中过饱和TDG和过量的泥沙威胁着下游鱼类的生存，成为水电工程运行的重大生态风险之一。而泥沙与过饱和TDG共同作用对鱼类影响的研究成果却十分匮乏，本项目以长江上游特有鱼类为研究对象，通过开展TDG过饱和与泥沙共同作用对鱼类的急性效应研究，指出了不同鱼类（岩原鲤、胭脂鱼、达式鲟等）对TDG过饱和含沙水体的耐受性各异，过饱和TDG与泥沙的共同作用对鱼类的生存影响大于TDG过饱和单独作用对鱼类的影响；TDG过饱和水体中，TDG过饱和是鱼类主要致死因素，泥沙加速了鱼类的死亡；通过研究不同鱼类受TDG过饱和胁迫后的早期生长发育特征的变化，初步获得TDG过饱和对不同鱼类早期生长发育的影响规律。通过大坝工程泄洪期间的现场实验研究，指出天然水体中的过饱和TDG对岩原鲤和胭脂鱼的耐受能力和回避能力的影响类似于以往室内受控实验结果。该研究丰富并深化了TDG过饱和水体对鱼类影响的研究成果，改善了目前国内关于天然水体中TDG过饱和对于鱼类影响研究匮乏的现状，对国内高坝工程泄水调度和鱼类的保护具有重要指导意义。