| As a technical means of managing urban water bodies,urban water body health assessment can not only analyze the current status of urban water bodies,diagnose the problems existing in urban water bodies,but also monitor the process of ecological restoration of urban water bodies,which can continuously serve the city.Follow-up adaptive management of aquatic ecological health provides feedback.Assessing the ecological health of urban water bodies is an important part of the urban water body ecosystem management process,and it is an indispensable link to achieve urban water resources management and a virtuous cycle of river basin ecosystems.Through a series of ecological monitoring and analysis of the water body in the old city of Suzhou,this study established a health evaluation system consisting of a target layer,a criterion layer,and an indicator layer with a total of 4 biological integrity evaluation indicators to evaluate the urban water ecosystem.Evaluation of health status.At the same time,with reference to relevant research results at home and abroad,and in combination with the actual situation of Suzhou water bodies,the evaluation criteria for the evaluation indicators and the evaluation standards for the ecological health of urban water bodies were determined.The expert consultation method is used to determine the weight of each evaluation index to evaluate the ecological health level of Suzhou water bodies.The results of ecological health assessment are combined with some water quality indicators to explore the factors that affect the ecological health status of Suzhou water bodies.The purpose is for the scientific development of urban water bodies in Suzhou City.And future development and utilization provide reliable and scientific basis.This study carried out a survey of large benthic invertebrate communities for 23 samples in Suzhou,on this basis,through the distribution range,discriminative ability and related analysis,the core indicators suitable for the evaluation of urban water ecological health are selected from the candidate indicators,the ratio method is used to calculate each core index and calculate the average value to obtain the biological integrity index(BIBI)of each benthic invertebrate.The results showed that a total of 22 species of invertebrate benthic animals were found in the urban area and reference points of Suzhou,belonging to 3 families,6 classes,9 orders,14 families.6 species of arthropods,2 classes,including 2 species of crustaceans,4 species of insects;11 species of mollusks,2 classes,10 species of gastropods,1 species of valve gills;5 species of annelids,3 of which are oligochaetes Species,2 species of leech.After correlation analysis,it is suitable to evaluate the BIBI index of Suzhou by the following 6 indicators,total taxa,arthropod taxa,Shannon-Wiener diversity index,percentage of species widely distributed,percentage of insects,percentage of individuals in the pollution-tolerant group composition,the best expected value of calculated BIBI value is 4.01,that is,BIBI value ? 4.01 is healthy,3.63 to 4.01 is good,3.26 to 3.63 is normal,2.89 to 3.26 is poor,and ? 2.89 is extremely poor.According to the BIBI results,the ecological health of water bodies in Suzhou is uneven,and the overall position is in a poor and extremely poor location.Through the correlation analysis of BIBI and various water quality factors,it is proved that the application of BIBI has a scientific guiding significance for the evaluation of urban water ecological health.There are 3 types of phytoplankton identified in Suzhou City,namely rotifers,branch horns and copepods,and the species rotifer> copepods> branch horns;phytoplankton 7 phyla,84 genera,227 species.Among them,Chlorophyta is the most,with a total of 78 species;Diatoms are the next,Cyanophyta is 35 species;Chlorella and Xanthophyta are least,they belong to the type of Chlorella-diatom-cyanobacteria.Seven indicators were finally selected for the health evaluation system,including phytoplankton species(P1),rotifer species(P4),phytoplankton Margalef richness index(P8),phytoplankton Pielou uniformity index(P10),phytoplankton Animal Margalef richness index(P11),branch angle density,copepod density(P16),and cyanobacteria abundance(P18).Based on this system,the classification standard of Suzhou city water body health is: PIBI value greater than 2.109 is healthy,and 1.76-2.109 is good,1.41-1.76 is fair,1.06-1.41 is bad,and less than 1.06 is very bad.The PIBI evaluation results are that most of the rivers in Suzhou in 2018 are in a healthy state,7 rivers are in a good and average state,and one river is in a very poor state.A total of 185 fishes were collected in the study area,belonging to 3 orders,5 families and 11 genera,including carps,pupae,pupae,pupae,and sand pond pupae,which accounted for 66.8,8.3%,and 8.3 of the total species,respectively.%,8.3%,and 8.3%.No cyprinididae was found,and Cyprinidae had the absolute advantage.Pollution-resistant species include loach and catfish.Fish were not collected at 43.5% of the observation points,and fish were collected at the other observation points.The FIBI index consists of the number of F1 fish species,the F3 Shannon-Wiener diversity index,the percentage of F10 bottom fish,and the number of F15 individuals.The FIBI value of the grading standard> = 1.723 is healthy,it is good between 1.548-1.723,it is normal between 1.375-1.548,it is poor between 1.202-1.375,and it is very poor at <= 1.202.The points are in a very poor state,4 points are poor,1 point is healthy,1 point is good,4 points are average.In the observation sites with fish,the health status is mainly concentrated in poor and average.The observation points of the extremely poor state are far higher than health and good.In general,the fish's biological integrity in the old city of Suzhou is very poor.A total of 5 species of aquatic plants collected in Suzhou were monitored,belonging to 4 families and 5 genera,and only submerged plants were detected.The diversity of aquatic plant species and communities in Suzhou City is low,and there are no aquatic plants in more than half of the sampling points.In the end,the Suzhou Aquatic Plant Integrity Evaluation System consists of the total number of species of VI,the number of native plant species of V8,V11 Perennial percentage,V15 Shannon-Weiner diversity index,V17 flora quality index(FQAI)composition.A VIBI value greater than 6.14 is healthy,good between 4.76-6.14,fair between 3.38-4.76,poor between 2-3.38,and very poor if less than 2.Samples of aquatic plants were collected,and most of the evaluation results were poor and extremely poor,and there were no healthy points.Therefore,the ecological health evaluation of aquatic plants in Suzhou is poor,and the restoration and management of aquatic plants must be strengthened.Finally,through comprehensive health evaluation,the HI index of the old city of Suzhou is between 1 and 3.8,and most of them are equal to 1.8,which indicates that the health status of urban water bodies in Suzhou is poor and extremely poor. |
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