Study On The Relationship Between Fish Community Structure And Plankton In Yudong Reservoi

The Yudong Reservoir is a key lifeline for the survival and happiness of the people in Zhaolu,with a large population.Therefore,maintaining the quality of water sources and ensuring the drinking water for residents is of great significance.In the ecosystem composed of fish community and other aquatic organisms in the reservoir,material and energy flows through the food web relationship between different organisms.The terminal of its material and energy flow is fish.In natural conditions,some small benthic fish are located in the middle stage of the material and energy flow pyramid,and their quantity and scale are much larger than predatory fish.However,due to the difficulty of fishing and the lack of economic value,they usually remain in reservoirs and cannot reduce the eutrophication level of reservoirs.Large and medium-sized predatory fish can transfer energy and matter by preying on small benthic fish,which can be transported out of the water through fishing to achieve nutrient removal.Through the investigation and analysis of fish community structure composition,ecological niche type and material and energy flow scale in the reservoir,the population number of aquatic organisms at each trophic level in the aquatic ecosystem in Yudong Reservoir can be understood.By calculating its material and energy conversion efficiency,the basic productivity in the water body of Yudong Reservoir and theoretically the occurrence amount of aquatic organisms at each level can be analyzed.Compare the occurrence with the detection data to determine whether the material circulation and transfer between different levels are sufficient,providing a basis for further optimizing the ecological community structure of fish in the Yudong Reservoir.This article draws the following conclusions through research:(1)The overall water quality of the reservoir is at the level of Class II,but the total nitrogen at almost all points exceeds the standard value for Class III water.Total phosphorus and chemical oxygen demand(COD)meet the requirements,and some measures may be taken for nitrogen removal in the next step.(2)By analyzing the density and biomass of planktonic animals and plants in the Yudong Reservoir,it was found that the amount of planktonic animals and plants increased from March to April in 2022,decreased in May,and then showed an upward trend from May to September.From this situation,it may be closely related to the special extreme high temperature weather in 2022 and its long duration.The high occurrence of planktonic flora and fauna in the summer of 2022 due to sustained high temperatures will lead to insufficient utilization of them by fish,and the remaining dead will be re deposited in the reservoir,which may lead to an increase in the occurrence of planktonic flora and fauna during the temperature rise in 2023.(3)The Yudong Reservoir used traditional fishing methods to collect fish,collecting a total of 10 species in 3 orders,4 families,and using eDNA technology to detect fish,a total of 32 species in 28 genera,8 families,and 4 orders were detected,revealing the limitations of traditional fishing methods.(4)During the research period,there were varying degrees of changes in the total number of fish and catch in the Yudong Reservoir.