Effects Of Water Eutrophication On Plankton Community Structure And Function In Jinan Urban Wetland

Wetland water ecosystem is an important part of the ecosystem,which is closely related to people’s life and production.With the continuous improvement of economic level and the gradual increase of urbanization pressure,the environment of wetland aquatic ecosystem has changed,the degree of pollution has gradually increased,the ecological environment has deteriorated,the water eutrophication status has been frequent,and the wetland aquatic ecosystem has been seriously damaged.Water eutrophication disrupts the intrinsic balance of aquatic ecosystems,resulting in damage to aquatic ecosystems,gradual degradation of functions,major changes in biodiversity,and serious threats to the biological components of the ecosystem.Eutrophication leads to the rapid growth of algae and other plankton in aquatic ecosystems,resulting in an increase in plankton biomass,an increase in the frequency of algal blooms,and further deterioration of water quality,which in turn leads to water quality that cannot meet the water source standards for drinking water,changes in species diversity,and changes in biodiversity will directly affect the function and structure of ecosystems.As a water ecological civilization construction city and sponge city,Jinan still has many urban water ecological problems.This study carried out investigation in 15urban wetlands in Jinan,based on water environment physical and chemical factors,biodiversity（taxonomic diversity,functional diversity）and ecosystem functions,and using comprehensive nutritional status index,One-way ANOVA,multiple comparison,linear fitting analysis and other methods to understand the comprehensive nutritional status of water quality in 15 urban wetlands in Jinan.To find out the effects of eutrophication on plankton community structure and diversity in Jinan’s urban wetland aquatic ecosystem;To find out the relationship between plankton biodiversity and ecosystem functions in urban wetland aquatic ecosystems with different trophic levels in Jinan.The results of the study are as follows:1.In this study,15 urban wetlands in Jinan showed three different nutrient levels,among which 3 were poor nutrient wetlands（Huashan Lake wetland,Chengbo Lake wetland and Rose Lake wetland）,and the comprehensive nutrient index of each wetland was between 23.93 and 29.11.There were six medium nutrient wetlands（Xueyehu wetland,Dashahe wetland,Yanziwan wetland,Tuma River wetland,Dawenhe wetland,Baiyun Lake wetland）,and the comprehensive nutrient index of each wetland was between 31.41 and 47.47.There were 6 mild eutrophication wetlands（Longshanhu wetland,Xiuyuanhe wetland,Wangjiafang wetland,Jinshui River wetland,Langxi River wetland and Jixi wetland）,and the comprehensive nutrient index of each wetland was between 52.72 and 57.52.It was found in this study that the water temperature of the three different trophic wetlands was similar and all were weakly alkaline water bodies.Eutrophication resulted in increased contents of TN,TP,NO₃-N and Chl-a,and the highest values were 6.83 mg/L,0.14mg/L,6.36 mg/L and 0.03 mg/L,respectively,in mildly eutrophication wetland.The average values of Cond,PO₄^3-content,NH₃-N content,SS content and COD_Mn index in medium nutrient wetland were 1252.50 us/cm,0.06mg/L,0.44 mg/L,77.88 mg/L and 4.12 mg/L,respectively.2.In this study,eutrophication led to an increase in plankton species richness,plankton diversity（Shannon diversity index,Simpson diversity index）,and plankton functional richness index.In mildly eutrophicated wetlands,The highest species richness（25 phytoplankton and 15 zooplankton）,the highest Shannon diversity index（2.75 phytoplankton and 2.77 zooplankton）,the highest Simpson diversity index（0.71phytoplankton and 0.73 zooplankton）,and the highest functional richness index（0.17phytoplankton and 0.22 zooplankton）.The mean values of phytoplankton classification and functionalβ-diversity were 0.396 and 0.063,and that of zooplankton were 0.341 and 0.036,respectively.The mean values of phytoplankton classification and functionalβ-diversity in meso-trophic wetland were 0.351 and0.052,and zooplankton were 0.663 and 0.062,respectively.The mean values of phytoplankton classification and functionalβ-diversity in mild eutrophic wetland were 0.335 and 0.051,and zooplankton were 0.647 and 0.077,respectively.The taxonomicβ-diversity was dominated by turnover components,and the functionalβ-diversity was dominated by nested components.The proportion of turnover components inβ-diversity was 63.72%,73.65%and 72.77%for phytoplankton and61.00%,50.79%and 54.46%for zooplankton in poor,medium and mild eutrophic wetlands,respectively.The proportions of nested components in functionalβ-diversity were 97.06%,80.16%and 79.74%of phytoplankton,56.00%,70.43%and 80.32%of zooplankton in poor nutrient,medium trophic and mildly nutrient-rich wetlands,respectively.3.The mean values of poor nutrient wetland,medium nutrient wetland and mild eutrophic wetland were 4.74,36.44 and 44.78 for phytoplankton and 0.49,0.64 and0.29 for zooplankton,respectively.The mean values of poor nutrient wetland,medium nutrient wetland and mild eutrophic wetland were 130.51,311.56 and 350.64 for phytoplankton and 0.42,0.08 and 0.03 for zooplankton,respectively.In this study,it was found that there were positive and negative correlations and uncorrelated relationships between biodiversity and ecosystem functions in nutrient-poor wetlands,medium-trophic wetlands and mildly nutrient-rich wetlands.In summary,in the 15 urban wetlands of Jinan,there are three different levels of nutrient levels:poor nutrition,medium nutrition and mild eutrophication.Eutrophication disrupts the intrinsic balance of wetland aquatic ecosystems,resulting in changes in plankton community structure and biodiversity,increasing plankton species richness,Shannon diversity index and Simpson diversity index,and plankton function richness index.The relationship between biodiversity and ecosystem function in nutrient-poor wetlands,medium-trophic wetlands and mildly nutrient-rich wetlands is either positively correlated,negatively correlated,and uncorrelated.This study is helpful to protect plankton biodiversity,maintain the health status of wetland aquatic ecosystems,provide a theoretical basis for further management of urban wetland eutrophication in Jinan,and serve as a reference for the national management of urban wetland eutrophication.