Water ecosystem quality assessment on rivers in Beijing City using benthic index of biotic integrity

Using biotic integrity index (B-IBI) of zoobenthos to evaluate river ecological environment conditions has become an important method for water ecological health assessment and management. We seasonally carried out investigation on macroinvertebrate, physical-chemical indicators and habitat quality at 115 sampling river sites in Beijing from autumn, 2020 to summer, 2021. Based on the investigation, the B-IBI of mountain rivers and plain rivers in Beijing was constructed, and the ecological status of the rivers were evaluated. The results of index selection showed that the B-IBI core indicators of mountain rivers included total number of taxa, EPT relative abundance, BMWP index, Clinger relative abundance, and Shannon-Wiener diversity index. B-IBI core indicators of plain rivers included total taxon number, relative abundance of Chironomidae, EPTO relative abundance, and relative abundance of pollution tolerant taxa. According to the changes of each parameter with the external interference enhancement, the score and the evaluation standard of each index were calculated by the ratio method. The evaluation results showed that the mountain rivers ecological condition were in "Good" condition, of which the Chaobai River systems were in "Good" condition, and the Jiyun River systems were in the worst of health condition, which were in "very poor" condition. The plain rivers were in "Fair" condition, of which the Yongding River and the Daqing River systems were in "Good" condition, and the Jiyun River, Beiyun River and Chaobai River systems were in "Fair" condition. There was no significantly difference in B-IBI among different seasons, and the overall ecological condition was not affected by seasonal changes, indicating that the B-IBI of Beijing had good stability in time. Multiple regression analysis showed that habitat quality was the main controlling factor limiting river ecological conditions in mountain and plain areas of Beijing, while CODMn and CODCr were the main factors affecting river ecological conditions in plain areas. The research showed that the B-IBI has a good indicator function for the habitat and water pollution status of the rivers in Beijing. The non-parametric tests indicated that, overall, the B-IBI scores of the reference sites were significantly higher than those of the impaired sites, which indicated the adaptability of the B-IBI assessment system in rivers of Beijing. © 2023 Science Press. All rights reserved.