Dynamic Changes And Influencing Factors Of Metazooplankton Community Structure In Suzhou Industrial Park

Suzhou Industrial Park is located in the lower reaches of the Yangtze River Basin.With the continuous progress of urbanization,the stability of structure and function of the aquatic ecosystem in the Park is facing severe challenges.Zooplankton,as an important part of the aquatic ecosystem,is of great significance for the biodiversity protection and healthy development of the ecosystem by researching the formation mechanism of its community structure.To better understand the community structure and influencing factors of metazoan zooplankton in Suzhou Industrial Park,four surveys were taken from Yangcheng Lake,Jinji Lake,Dushu Lake,Shahu Lake,Baitang Lake,Wusong River and Qingqiupu River in July 2018,October 2018,January 2019 and April 2019,respectively.Also,habitat factors closely related to the survival and distribution of zooplankton were determined.The species composition and distribution of metazoan zooplankton,the seasonal succession of dominant species,the temporal and spatial changes of density,biomass and biodiversity,and their relationship with habitat factors were discussed in detail.And the biological evaluation of water quality in the Park was carried out.The main results were as follows:1.A total of 119 metazoan zooplankton species were detected in this study,including 70 species of Rotifera belonging to 31 genera of 11 families,30 species of Cladocera belonging to 17 genera of 7 families,and 19 species of Copepoda belonging to 15 genera of 9 families.Among them,112 species(including 65 species of Rotifera,29 species of Cladocera,and 18 species of Copepoda)were detected in lakes,and 88 species(including 47 species of Rotifera,24 species of Cladocera,and17 species of Copepoda)were detected in rivers of the Park.There were 7 dominant species in both lakes and rivers,including Brachionus calyciflorus,Anuraeopsis fissa,Keratella cochlearis,Polyarthra trigla,Conochilus unicornis,Bosmina longirostris,and Nauplii.The density,biomass,Shannon-Wiener diversity index,Pielou evenness index and Margalef richness index of metazoan zooplankton in lakes showed significant seasonal differences.And except for density,the biomass,diversity index,evenness index and richness index of metazoan zooplankton in rivers showed significant differences on season aspect.2.In terms of the species composition of community structure,Jaccard similarity analysis showed that the species composition between Jinji Lake and Shahu Lake was moderately dissimilar,while the species composition among other water bodies was moderately similar.The ANOSIM similarity analysis based on species composition and abundance indicated that the community differences of metazoan zooplankton in the seven water bodies were significantly greater than that of intra-group.The results of Kruskal-Wallis H test showed that only the density of metazoan zooplankton had significant spatial differences,while there were no significant differences in biomass,diversity index,evenness index and richness index.Cluster analysis based on species number,density,biomass and the above three diversity indices suggested that the metazoan zooplankton community structure was the most similar between summer and autumn in the lakes,while the community structure of the rivers was the most similar between spring and summer,and the community structure between Jinji Lake and Baitang Lake was the most similar at the spatial level.3.The results of redundancy analysis showed that water temperature,pH and dissolved oxygen were the main environmental factors affecting the population density of dominant species of metazoan zooplankton in lakes and rivers.Pearson correlation analysis indicated that community structure of metazoan zooplankton in lakes and rivers was correlated with water temperature,pH and transparency,but not with dissolved oxygen,total dissolved solids,nearshore distance of sample sites and water area.Multiple linear regression analysis suggested that temperature was positively correlated with the species number,density and biomass of metazoan zooplankton in lakes,as well as with the species number and biomass of metazoan zooplankton in rivers.In conclusion,temperature may be the decisive environmental factor for the change of metazoan zooplankton community structure in the Park.4.Using zooplankton with pollution indicator function to evaluate water quality,it indicated that the water quality of the Park was basically in a state of moderate pollution.According to the water quality evaluation standard based on the zooplankton diversity index,Shannon-Wiener diversity index and Margalef richness index were consistent in the evaluation of water quality in the Park,both of which indicated that the water was in a moderate pollution state,and Pielou evenness index showed that the water quality was in the state of light to moderate pollution.In addition,both the diversity index and evenness index showed that the water quality of Jinji Lake was the worst in the Park.Therefore,the investigation into water pollution sources and ecological management should be carried out in time.