| Freshwater ecosystems play an important role in human society but they were severely damaged on account of development of industry and agriculture which caused the degradation of ecosystem.In developed countries,macroinvertebrate is used as a common species for health assessment which is essential for restoration of freshwater ecosystem.From 1980s,researchers started to use macroinvertebrate to evaluate the health condition of freshwater ecosystem in China.However,most mature assessment systems in foregin country were not suitable for China because they usually need a large amount of data with professional knowledge.With the diverse ecosystems and disturbances in China,it is great important to e stablish macroinvertebrate-based health assessment system with the exploration of distribution pattern and rare taxa of macroinvertebrate.Tuhai River and Majia River are important rivers in North Shandong province in China.During the 12th Five-Year Plan,the water quality in Tuhai River and Majia River was greatly improvement by restoration projects of government.In this paper,we 1)explored the influencing factors on distribution of macroinvertebrate based on the multi-year data of Tuhai River,Majia River,Yanhuang River and Zhaoniu Constructed Wetland as well as 2)the effects of abudments on macroinvertebrate community.3)We also analyzed the distribution pattern of macroinvertebrate in large-scale area based on the data of 62 lakes.4)Use the supposal model to analyze the responses of biological indices to rare taxa excluding.The main results in this paer are as follows:Results of field research revealed that there were 16 taxa collected in studied rivers and 18 taxa in Zhaoniu Constructed Wetland.The community structures were significantly different bet ween rivers and wetland.On account of difference of dominant species,abundance and richness were also different from sites to sites.The constructed wetland in Zhaoniu River showed a great improvement on macroinvertebrate community.Although much work have been done on the restoration of ecosystems and water quality,it is still not suitable to use general methods in this area.Based on the several factors such as macroinvertebrate community,hydrological condition,water quality,we established an indicator species based assessment method for Hai River Basin.The correlation of biological characteristics between under-bridge sites and reference sites suggested that the abudments would father effect the community in polluted rivers.The benthic macroinvertebrate community characteristics such as density,biomass richness and Shannon-Wiener index were significantly correlated between under-bridge sites and references(0.961,0.931,0.930 and 0.603 respectively).There were no significantly different between under-bridge sites and reference sites in terms of abundance and biomass while significantly different in terms of richness and Shannon-Wiener index.This pattern outlined a major impact of bridge abutments on benthic macroinvertebrate communities for the first time,indicating the importance of habitats restoration after river constructions were finished.To document the patterns of macroinvertebrate species richness and their possible causes in Chinese lakes at a regional scale,we collected data on macroinvertebrates in 62 Chinese lakes.A correlation analysis was used to explore the patterns of macroinvertebrate species richness across seven variables:lake area,lake volume,catchment area,lake mean depth,mineralization,mean annual temperature,and mean annual precipitation.Results showed that the factors influencing macroinvertebrate species richness were catchment area(R~2?0.380,p<0.001).Richness was positive correlated with the volume in lake of eastern region(R~2=0.220,p<0.001)while it was positive correlated with lake area in both eastern and western region(R~2=0.280,p<0.001;R~2=0.533,p=0.002).Richness was more significantly correlated with lake area with fewer disturbances while more significantly correlated with lake volume with more disturbances.It reveals that macroinvertebrate structure would be more resistant to drought and flood in natural condition.In addition,the distribution pattern of macroinvertebrate in large scale area was different from classical species-area relationship.It is much more significant correlated with the catchment area than lake area.In conclusion,catchment area explains the spatial variation of macroinvertebrate species richness across Chinese lakes.Geomorphology should be involved in the study of benthic macroinvertebrates because of its correlation with catchment area.The species catchment area hypothesis provides more plausible explanations for the spatial pattern of macroinvertebrate species richness than the traditional speciesarea hypothesis in lakes across China,which suggests that the classical traditional 'species area curve' might be replaced by the 'speciescatchment area curve' for macroinvertebrate species in lakes.In the present paper,we hypothesize that biological indices such as Shannon-Wiener Index,Simpson's Index,Margalef Index,Evenness,BMWP(Biological Monitoring Working Party)and ASPT(Average Score Per Taxon)respond differently to rare taxa exclusion.To test this hypothesis,a benthic macroinvertebrate data set based on recent fifteen-year studies in China was built for suppositional plot analyses.A field research was conducted in the Nansi Lake to perform related analyses.The results of suppositional plot simulations showed that Simpson's Index placed more weight on common taxa than any other studied indices,followed by Shannon-Wiener Index which remained a high value with the exclusion of rare taxa.The results indicated that there were not much of effect on Simpson's Index and Shannon-Wiener index when rare taxa were excluded.Rare taxa played an important role in Margalef Index and BMWP than in other indices.Evenness showed an increase trend while ASPT varied inconsistently with the exclusion of rare taxa.Results of the field study also indicated that rare taxa had few impacts on the Shannon-Wiener index.By examining the relationships between the rare taxa and biological indices in our study,it is suggested that including the rare taxa when using BMWP and excluding them in the proposed way(e.g.fixed-count subsampling)to calculate Shannon-Wiener Index and Simpson's Index could raise the efficiency and reduce the biases in the bioassessment of freshwater ecosystems.Overall,in order to study macroinvertebrate for health assessment,this paper combined with both theoretical and practical research,involving human disturbance and environmental influence.The health condition in Zhaoniu Constructed wetland was successfully assessed by this method during the ecological restoration procedure.The effects of abutment on macroinvertebrate community were firstly detected in scientific way and suitable measures should be taken to minimize the impact of bridge abutments.Results of distribution pattern of macroinvertebrate in large scale suggests that the classical 'species-area curve' might be replaced by the 'species-catchment area curve' for macroinvertebrate species in lakes.Study on rare taxa excluding provides a critical test for the responses of biological indices to rare macroinvertebrate taxa exclusion.Responses of indices vary from each other when rare taxa are excluded.Results indicates that including the rare taxa when using rapid qualitative index(BMWP)and excluding them in the proposed way(e.g.fixed-count subsampling)to calculate diversity indices(Shannon-Wiener Index and Simpson's Index)could raise the efficiency,reduce the workload and avoid biases in the bioassessment of freshwater ecosystems. |
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