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

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