Water ecological health assessment based on the biological integrity of macroinvertebrate: a case from Liaohe River Basin

The benthic index of biological integrity (B-IBI) is widely used for river ecological health assessment all over the world. However, this index should be constructed separately according to the ecological environmental characteristics of each river basin. In this study, the Liaohe River Basin was taken as an example, the data of macroinvertebrates of 99 sites in Liaohe River Basin was used to calculate to B-IBI. Water quality and habitat quality were comprehensively used as the selection criteria for reference sites and impacted sites. The distribution range test, discriminant ability test and redundancy test were used to screen the core metrics of B-IBI. The ratio method was used to standardize the core metrics and add up to calculate B-IBI. The results showed that a total of 74 taxa of macroinvertebrates were found, and the dominant taxon was Insecta (accounting for 81.1% of the total taxa). The most dominant species was Hydropsyche kozhantschikovi. Five reference sites and six impacted sites were obtained after screening. Six core metrics including the number of total taxa, the taxa number of Trichoptera, the taxa number of Amphipoda and Mollusca, the relative abundance of direct collectors, the number of adherent taxa, and the Pielou evenness index, were selected from 28 candidate metrics. The evaluation results of B-IBI showed that 4 sites were in health grade, 15 sites in sub-health grade, 25 sites in normal grade, 41 sites in poor grade, 14 sites in bad grade, and the whole health level of Liaohe River Basin was poor in the survey period. The macroinvertebrate community was impacted in more than half of the sampling sites. B-IBI showed a good indicating ability for the change of water quality in Liaohe River Basin, and effectively distinguish damaged sections of the river. It was suggested that B-IBI could be used as a bioassessment tool for the river basin management in future.