Applicability of macrobenthos indexes in health assessment upstream of a large river: A case study in the Babian River of the Red River Basin, China

Abstract

Biological assessment is an important component of river health assessments. With the thorough growth of river health assessment in China, the scientific verification and screening of straightforward, easily quantifiable, and widely used bio-assessment indexes has emerged as a significant scientific challenge that needs to be resolved immediately in river health assessment. In 2019, 28 sections of the Babian River were examined for water quality, macrobenthos, status of the riparian zone and societal value. Based on the presence of macrobenthos in river health assessments, the applicability of 17 indexes was analyzed. The indexes that could differentiate between reference sites and impaired sites were B-IBI, S2, S3, and BMWP, which had good correlation with environmental factors. Although there was no significant link with riparian conditions, B-IBI, S2, S3, and BMWP had strong negative correlations with total ammoniacal nitrogen, total nitrogen, and total phosphorus but S2, S3, and BMWP are effective alternatives for B-IBI in river health assessment since their results were comparable to those of B-IBI, which covered all the assessment grades. Moreover, when constructing and selecting a bio-assessment index, more attention should be paid to the role of dominant and rare species, as well as the appropriate condition of indexes. In addition, riparian condition is a necessary aspect of river health assessment, but it is challenging to reflect the influence of land components on river health because of the small scale of riparian investigation. Therefore, it is necessary to introduce basin-scale indexes to optimize river health assessment systems. By doing this, watershed system management and overall governance will be supported more effectively.