Application of multiple biological indices for river health assessment in northeastern China

Abstract

Bioassessment has become a hot topic and could provide important information for river management and restoration. In this study, we developed multiple biological indices using three groups of aquatic organisms - benthic algae, macroinvertebrates and fish - for river health assessment. The main steps for development of multiple biological indices were selection of sensitive indices, optimization of core indices, setting target and critical values for core indices, and calculation of final scores of health condition. In order to evaluate the 19 candidate indices, disturbance gradients were constructed for water contamination, sediment contamination and land use change using principal components analysis. Thirteen indices showed significant and relatively high coefficients of determination with the disturbance gradients using multiple regression analysis (P<0.05). Six indices - two indices each for benthic algae, macroinvertebrates and fish - were finally selected as the core indices using correlation analyses. River health condition scores were assigned to five categories: critical, poor, fair, good and excellent. One site was classified as critical and 10.5% of sites were in poor condition. Meanwhile, 45.6% of the sampling sites were classified as fair and 42.1% were either good or excellent. Regression analysis between the final scores and disturbance gradients confirmed the usefulness of multiple biological indices as a confident bioassessment method. Thus, we highly recommend using multiple biological indices to assess river health that will inform river management and restoration strategies.