Revision And Applicability Study Of The BMWP Evaluation System For Benthic Macroinvertebrate

In the early stages of water environmental management in China,the physical and chemical properties of water bodies were the main reference basis.Currently,with the national water ecological civilization construction,the goal of ecological environment management has shifted towards the health of water ecosystems.Overseas,the evaluation of water ecological quality mainly relies on aquatic biological indicators.In Europe,assessment methods based on aquatic biology were established in the early twentieth century.Due to the advantages of the widespread distribution of large benthic animals,easy collection of identification data,and diverse evaluation indices,this approach gradually became the main tool for water quality biological assessment.The BMWP evaluation system is one of the commonly used indicators in river monitoring with simple and practical classification requirements.However,the composition of benthic macroinvertebrate communities varies in different biotic environments,and the response to organic pollution of the same taxonomic unit is not the same under different habitat conditions.Particularly in the Taizi River basin,which has diverse benthic animal community structures and significant differences in water quality and hydrological environments between upstream and downstream,further research on the localized revision of the BMWP evaluation system is needed.Therefore,based on the unique characteristics of the Taizi River basin,this study referred to the revision method of the sensitivity value of foreign benthic macroinvertebrate taxa to form different versions of the BMWP evaluation system.By screening the response relationship of water quality parameters,this study selected a set of BMWP evaluation system and standards suitable for evaluating the health status of the Taizi River basin.Comparing the selected BMWP evaluation system with other biological evaluation indicators,it was found that the evaluation system is more suitable for evaluating the health status of the Taizi River basin.In order to promote the application of the revised BMWP evaluation system,this study applied the evaluation system to the Hunhe River and the Western Liao River.The results showed that the evaluation system is applicable to the Hunhe River to a certain extent,but not suitable for the Western Liao River.The achievements of this study can not only provide localized rating criteria and evaluation standards for the health assessment of rivers in northeastern China,but also provide technical support for the management of aquatic ecological environment in China.In order to select a suitable BMWP evaluation system for the Taizi River,we first used principal component analysis（PCA）to identify the main parameters affecting water quality in the Taizi River basin,namely ammonia nitrogen（NH₃-N）,total nitrogen（TN）,dissolved oxygen（DO）,and total phosphorus（TP）.Based on the response relationships between different revised BMWP evaluation systems for benthic macroinvertebrates and water quality parameters,we found that the Mexico method-based sensitivity value revision method was more suitable for evaluating the health of the Taizi River.We also divided the comprehensive pressure range of water quality in the basin into five levels based on the results of the first principal component analysis（PCA1）,and determined the rating of the revised BMWP evaluation system according to the response model,in order to form an evaluation standard.In order to investigate the suitability of the revised BMWP evaluation system in the Taizi River basin,we compared this evaluation system with Shannon-Wiener diversity index,Pielou evenness index,Margalef richness index,FBI index and EPT-Fa%index in terms of water quality assessment using redundancy analysis（RDA）.We also compared the trends of different biological indices with water quality grades,and the trends of water quality parameters between different biological index evaluation grades.We used box plots combined with Kruskal-Wallis non-parametric tests for analysis,and found that the revised BMWP evaluation system performed well in all biological assessment indices,demonstrating its significant application value for river water quality assessment.A revised BMWP evaluation system and regression model for water quality parameters were constructed using multiple linear regression analysis.The model was used to calculate the predicted value(BMWP-M_expected)of the revised BMWP evaluation system for Taizi River.A scatter plot was used to establish the linear relationship between the observed value(BMWP-M_observed)and the predicted value(BMWP-M_expected)of the revised BMWP evaluation system,and the feasibility of applying this system to other rivers was explored based on a 95%prediction interval.The results showed that the revised BMWP evaluation system could be applied well to Hun River,but not to Western Liao River.It is recommended that the evaluation system should be revised according to the specific conditions of the river before use to achieve more accurate evaluation.