The Influence Of Environmental Stress On The Growth Of River Clams In Taihu Lake

Based on the collection and sorting of paper,controlled experiment,laboratory experiments methods,we studied the effects of temperature and food quality on the feeding and excretion of Corbicula fluminea of Taihu Lake,and the effects of substrate and dissolved oxygen on the survival and growth of C.fluminea of Taihu Lake.On this basis,the effects of mechanical oxygen addition on the survival and growth of C.fluminea of Taihu Lake under different substrate and water depth were carried out,the purpose of this study is to provide scientific support for the application of river sturgeon in aquatic ecological restoration.The results were as follows:The effects of temperature and food quality on feeding and excretion of C.fluminea were simulated through laboratory experiments.Seven experimental temperatures were set between 20? and 32?,and five different food quality,i.e.100% lake water,50% lake water + 50% Scenedesmus obliquus,100% Scenedesmus obliquus,50% Scenedesmus obliquus + 50% Microcystis aeruginosa,100% Microcystis aeruginosa,were considered.Feeding rates and excretion rates of C.fluminea under different conditions were measured.The results indicated that feeding rate of clams increased with the temperature,and then decreased gradually after reaching the maximum temperature of 24?.The temperature and food quality had significant impacts on feeding rates and excretion rates,and the effects of the two factors were interacted.The effect of food quality on the feeding rate of C.fluminea was weakened under the stress of high temperature.The high temperature in summer would lead to high energy consumption,and the outbreak of cyanobacteria blooms would result in low food quality.Thus,these two factors would reduce the amount of energy available to C.fluminea for growth and reproduction,which could be one of the main reasons for population decline of C.fluminea in Lake Taihu.Through the controlled experiment,Taihu Lake sediment was mixed with quartz sand as the mixed sediment(mixing),and Taihu Lake sediment was mixed as the lake sediment(lake mud).Based on the negative correlation between suspended water depth and dissolved oxygen,a water depth of 1 m is a high oxygen treatment,and a water depth of 2m is a low oxygen treatment.The types of dissolved oxygen and sediment were combined to form four treatment groups,i.e.low oxygen mixing,high oxygen mixing,low oxygen lake mud and high oxygen lake mud.By measuring the survival rate and growth of C.fluminea under different treatment conditions,the influence of environmental factors onthe survival and development of C.fluminea was revealed.The results showed that the dissolved oxygen content and the type of sediment had significicant effects on the survival rate of C.fluminea,and the mixed sediment in the low-oxygen environment could increase the survival rate of C.fluminea by more than 50%.It can be seen that the sediment can significantly improve the survival rate of C.fluminea.The growth rate and fertilizer content of C.fluminea in the mixed substrate are higher than that in the lake mud substrate,which provides a scientific basis for C.fluminea culture and promotes the economic development of aquaculture.The effects of different sediment and water depth on the survival and growth of C.fluminea were determined by outdoor controlled experiment.The experiment divided the sediment and water depth into four treatment groups: mixing 2 m,mixing 1 m,lake mud 2m and lake mud 1 m.The survival rate and growth rate were taken as the growth and survival index of C fluminea.The results show that although the survival rate of C.fluminea can be increased by aeration,excessive aeration will seriously affect the feeding and growth of C.fluminea and the efficiency of water restoration.Under the condition of mechanical aeration,good substrate can increase the relative growth rate of C.fluminea.In the mechanical aerated water body,different kinds of water have no significant effect on the survival and growth of C.fluminea.The methods of lifting samples cannot reduce the effect of aeration on the growth of C.fluminea in the mechanical aerated environment,which provides a theoretical basis for the cultivation and aquatic ecological restoration of C.fluminea.