Characteristics Of Community Structure Of Benthic Macroinvertebrate And Aquatic Ecosytem Health Assessment In The Qin River Of Jincheng Region

The health of Qin River which is the largest river in Jincheng region shanxi province has been widely concerned because the impact of human activities on the river ecosystem has become more and more serious.Water physicochemical parameters and macroinverbrates were investigated and analyzed at 49 sites in Qin River and its largest tributary(Dan River)in October 2020.The community structural characteristics of macroinvertebrates including species,density,bio-diversity and feeding functional group were analyzed.The relationship between the biological indicators and environmental variables was explored based on canonical correspondence analysis(CCA)and redundancy analysis(RDA).A Index of Biotic Integrity based on maconinvertebrates(B-IBI)was established to evaluate ecosystem health of Qin River in Jincheng region.The main conclusions are as follows:(1)A total of 38 species of macroinvertebrates(29 species of Qin River and 31 species of Dan River)were collected and identified at 49 sampling sites of Qin River and Dan River in Jincheng region,belonging to 3 phyla,6 orders and 19 families.19 species that belonged to Arthropoda accounted for 50.00% of total species,which were mainly composed of Mayfly,Diptera,Trichoptera,and Odonata of the order Insecta.14 species that belonged to Mollusca accounted for 36.84% of total species,which were mainly composed of Gastropoda.5 species that belonged to phylum Annelida accounted for 13.16% of total species,which were mainly composed of Tiberias.The dominant species in Qin River were Chironomus riparius Meigen,Ephemera orientalis,Limnodrilus claparedianus and Corbicula fluminea,and the dominant species in Dan River was Chironomus riparius Meigen.As a only intolerant species,Ephemera orientalis mainly distributed in Qin River and accounted for 6.9% of total species.The sites in the upper-middle reach of Qin River and the middle reach of Dan River were characterized by high abundance and number of tolerant species.34.48% and 41.94% of total species belonged to tolerant taxa in Qin River and Dan River,respectively.Collectors(GC)and Filter feeders(FC)were the main functional groups and occurred with the highest frequency more than 60%,indicating that water pollution was serious in Qin River and Dan River in Jincheng region.(2)The results of CCA between the abundance of species of macroinvertebrates and environmental factors in Qin River and Dan River showed that the abundance of Ephemera orientalis increased with water body% and grass land% increasing,and decreased with agricultural land% increasing in Qin River.The abundances of Chironomus riparius Meigen and Limnodrilus claparedianus were positively correlated with ammounia nitrogen concentration and agricultural land%,sulfate concentration,forest land% and urban land%.The abundance of Chironomus riparius Meigen increased with urban land%,fluorine ion concentration and ammonia nitrogen concentration increasing.(3)The results of RDA showed that the abundance of GC was positively correlated with agricultural land%,p H and ammonia nitrogen concentration.The abundance of FC was positively correlated with forest land%.The abundance of GC in Dan River was positively correlated with ammonia nitrogen concentration,fluorine ion concentration and urban land%.The abundance of FC was positively correlated with fluorine ion concentration and urban land%.(4)The results of ecosystem health assessment of Qin River in Jincheng region showed that 5 sites were classified into "Excellent" level and 10 sites were classified into "Good" level,and the "Excellent" and "Good" sites accounted for 30.61% of total sampling sites,and 12 sites were classified into "Poor" level and 12 sites were classified into "Very poor" level,and the both accounted for 48.98% of total sites.Ammonia nitrogen concentrations and total nitrogen concentrations were significantly negatively correlated with B-IBI values,and the distribution of and tolerant species was contrary with B-IBI values,which indicated that the B-IBI constructed in this study is applicable of Qin River in Jincheng section.