Study Of Community Structure Of Zoobenthos And It’s Applications Of Water Quality Assessment In Shanghai Mini And Medium Rivers

From May2012to January2013, zoobenthos community in8urban rivers of8districts in Shanghai city was seasonally investigated. The rivers are Xujiazhai riverof Zhabei district, Youyi river of Minhang district, Zhonghenggang river of Qingpudistrict, Pilu river of Chongming district, Xinlugang river of Fengxian district,Yonggan river of Jinshan district, Maojiatang river of Baoshan district, Qumen riverof Jading district. Water quality of the river was assessed based on the structure ofzoobenthos community. Redundancy analysis (RDA) and Canonicalcorrespondence analysis (CCA) were applied to analyze the relationship betweenthe density and biomass of zoobenthos and environmental factors. The researchintends to select the preferable zoobenthic indicator for water quality evaluation andproposed to provide reference for biomonitoring and ecological restoration inShanghai rivers. The results as follows:1. Variation of physical and chemical indicators of water quality: The physicaland chemical indicators of water quality showed significant temporal and spatialvariation in8Shanghai rivers. From spring to winter, concentrations of CODMnwere10.37~19.14mg/L,7.83~17.58mg/L,7.51~16.01mg/L,8.01~20.30mg/L,respectively; concentrations of TN were2.57~5.48mg/L,1.04~5.14mg/L,1.08~5.99mg/L,2.5~9.19mg/L, respectively; concentrations of TP were0.08~1.08mg/L,0.39~0.80mg/L,0.16~0.51mg/L,0.29~0.82mg/L, respectively;concentrations of DO were2.46~4.61mg/L,1.64~10.44mg/L,4.3~10.62mg/L,4.12~8.25mg/L, respectively. 2. Physical and chemical indicators of water quality assessment: Water qualityof8Shanghai rivers varies from Level IV to worse than Level V. Among which, thewater quality of Pilu river of Chongming district was better compared to otherrivers, the worst water quality were in Xinlugang river of Fengxian district andXujiazhai river of Zhabei district, the rest rivers water quality ranged between thesetwo styles.3. A total of43zoobenthos species belonging to3phyla19families and33genera were identified, among which Limnodrilus hoffmeisteri and Chironomusflaviplumus were dominated. The annual density of zoobenthos averaged382.0ind/m2and Limnodrilus hoffmeisteri contributed the most (77.4%) of the gross.The annual biomass of zoobenthos averaged24.62g/m2and Bellamya aeruginosacontributed the most (86.0%) of the gross. The zoobenthos had the highest densityin summer, followed by winter, autumn and spring. The highest biomass was inwinter, followed by autumn, summer and spring. The highest density was inXujiazhai river of Zhabei district, the lowest density was in Youyi river of Minhangdistrict, The highest biomass was in Yonggan river of Jinshan district, the lowestbiomass was in Xujiazhai river of Zhabei district.4. Through the selected five kinds of biological indices for a comprehensiveevaluation of the8Shanghai rivers, the evaluation results indicated that the waterquality of8Shanghai rivers were of slight to serious pollution, In8rivers of8districts in Shanghai, only one river was in slight pollution, three rivers in moderatepollution, four rivers in serious pollution. Biotic Index (BI) and Goodnight BioticIndex (GBI) were much more suitable for the evaluation of river water quality in8Shanghai rivers comparing with Shannon-Wiener diversity index, Margalef speciesrichness index, Pielou index.5. Cluster analysis and multidimensional scaling analysis were used to classifythe zoobenthos community structure in8Shanghai rivers. The results of the twomethods were consistent, dividing into three categories: Class I, Pilu river ofChongming district was alone as a class, may be due to its located in the suburb and was of less pollution, so it had higher species diversity; Class II, Youyi river ofMinhang district, Zhonghenggang river of Qingpu district, Xinlugang river ofFengxian district, Yonggan river of Jinshan district, Maojiatang river of Baoshandistrict, Qumen river of Jading district, this may be due to the similar habitats, sothe zoobenthos community structure were similar; Class III, Xujiazhai river ofZhabei district, because Zhabei is located in the city, pollution was more serious, sothe species type was less and mainly stain resistant species. The communitysimilarity index confirmed the results of the cluster analysis and multidimensionalscaling analysis.6. This study analyzed the effects of8environmental factors on zoobenthos,results show that: different types of zoobenthos had different adaptability andsensitivity to the environment, but the relationship between the same genus orspecies and environmental factors was consistent. Among the8environmentalfactors, Temperature, Dissolved oxygen, Total nitrogen and Chemical oxygendemand have important influence on the zoobenthos species, but it didn’t mean theother four kinds of environment factors had no or very small effect on zoobenthosspecies, it is unknown that their combined effects with other environmental factorsmay be more significant to zoobenthos species.