Mesocosm Experiment On The Influence Of Biomanipulation On Water Quality In Lake Chaohu

In view of the severe cyanobacteria blooms in Lake Chaohu in summer,and the eutrophication of the water body is becoming more and more serious,this study intends to use a classic biological manipulation of control measures to carry out aquatic ecological restoration experiments on Lake Chaohu water body.At the same time,it will conduct a year-long water quality and phytoplankton in Lake Chaohu.Monitoring the composition of animal communities.The feasibility of biological manipulation in the whole lake was analyzed and discussed by observing the water quality of surrounding water bodies and the characteristics of zooplankton community changes,and combining the characteristics of the lake's water quality,zooplankton and fishery structure.The main results were shown below:(1)In the enclosure experiment,the chlorophyll concentration in the enclosure of the low-density group decreased by 69.32% at the end of the experiment;at the end of the experiment in the high-density group,the chlorophyll concentration in the enclosure at the end of the experiment decreased by 55.59% compared to the beginning of the experiment;The algae in the enclosure has good control effect.(2)The effect of enclosure experiments on the removal of nutrients from water was as follows: the removal efficiency of phosphorus in enclosure water by the low-density group and the high-density group was more than 90%,which were 98.50% and 93.68%,respectively;The removal efficiency of nitrogen is relatively low,so this method is more suitable for experiments aimed at controlling phosphorus content.(3)A total of 61 zooplankton were detected in the enclosure during the experiment.No pollution occurred in the enclosure of the low-density group with the indicator species Brachiaria rotifera as the dominant species during the experiment.Brachionus calyciflorus is the dominant species,so judging from the composition of zooplankton,the biological regulation effect of the low-density group is better than that of the high-density group.(4)By analyzing the characteristics of the water quality,zooplankton and fishery resources of the whole lake,it is found that the water quality of the northwestern part of Lake Chaohu has the worst deterioration.The species of zooplankton are small and the characteristics of miniaturization are obvious.The preparation of fishery resources is far lower than the enclosure setting.In summary,the control of carnivorous fish algae on cyanobacteria blooms in Lake Chaohu,the reduction of nutrients in the water body and the optimization of the zooplankton community composition have significant effects;meanwhile,the implementation of carnivorous fish algae control measures across the lake It has certain difficulties,but it is very necessary.Therefore,in the subsequent implementation process,multiple measures such as zonal governance,banning fishing,and optimizing the biological structure of Lake Chaohu can be used to gradually restore the water environmental quality of Lake Chaohu.