Biological evaluation of Michigan's non-wadeable rivers using macroinvertebrates

Non-wadeable rivers are relatively understudied compared to smaller, wadeable streams. Currently, protocols exist in most states, including Michigan, to evaluate the ecological condition of wadeable streams, but few protocols exist for larger, non-wadeable rivers. The goal of this research was to develop a multimetric index of biological integrity for Michigan's non-wadeable rivers, and we sampled 28 unique river reaches in Michigan that encompassed a wide range of human impacts and ecological conditions. In each reach, we collected physical, chemical, and macroinvertebrate samples. Using several techniques to eliminate redundancy among metrics and identify those biological attributes that correlated with anthropogenic influences, we developed a useful protocol that will allow the rapid bioassessment of such rivers in Michigan. When used together with the Non-wadeable Habitat Index, the Non-wadeable Index of Biotic Integrity (NW-IBI) will allow objective evaluation of non-wadeable rivers in Michigan.