Analysis On The Effects Of Reservoir Impoundment Of Jingdezhen Wuxikou Hydro-Project On Plankton In Changjiang River Basin

Wuxikou Hydro-Project is located in the main stream of Changjiang River.The reservoir impoundment will inevitably affect the water ecological environment and plankton.To investigate the effects of water storage on water ecology and plankton,the water physical and chemical factors and phytoplankton community structure sampling investigation were collected in March(before reservoir impoundment),April(in initial reservoir impoundment)and August(after reservoir impoundment)2019 in Changjiang River basin,by analysing the change of water physical and chemical factors,to understand the dynamic change rule of water physical and chemical factors in Changjiang River basin.By analyzing the change rule of phytoplankton community structure before and after reservoir impoundment.Meanwhile,explored the main environmental factors which influenced the phytoplankton community structure in Changjiang River basin by redundancy analysis method(RDA),analyzed the change rule of main influencing factors,discussed the influence of Wuxikou Hydro-Project reservoir impoundment on plankton community structure.The main results are as follows:1.After reservoir impoundment,the water level rises significantly,the flow rate slows down,the transparency increases,the dissolved oxygen content increases,and the content of organic matter,N,P and other nutrients increases.Behind the dam,the content of organic matter,N,P and other nutrients in water decreases.The tributaries behind the dam were less affected by the impoundment and the physical and chemical factors changed less.2.There is a great similarity in the composition of plankton community in the whole Changjiang River Basin.The phytoplankton community changed from diatoms before reservoir impoundment to diatoms and cyanobacteria after reservoir impoundment.Rotifers were the main zooplankton species before and after reservoir impoundment.The number of dominant species of rotifers decreased in initial reservoir impoundment and increased after reservoir impoundment.The number of dominant species and diversity of phytoplankton community increased after reservoir impoundment.The biomass and abundance of plankton increased after reservoir impoundment in front of dam,but decreased behind dam.The nearer to the dam,the greater the increase of biomass and abundance.The quality of Changjiang River basin was good,and the overall water quality was in a light pollution state.After the impoundment,the water quality was improved.3.The results of redundancy analysis(RDA)showed that after reservoir impoundment,the environmental factors limiting the development of plankton community were reduced,indicating that the overall water environment of The Changjiang River basin was developing in favor of plankton.