Development of a preliminary invertebrate index of biotic integrity for Lake Huron coastal wetlands

The biota of aquatic systems are integrators of overall habitat quality, revealing both episodic as well as cumulative disturbance, and therefore are able to serve as natural monitors of the systems they inhabit. Invertebrate communities from three relatively pristine coastal wetlands located along the northern shore of Lake Huron were compared to those from three relatively impacted Saginaw Bay coastal wetlands in Lake Huron to identify components of the community that could ordinate wetlands according to anthropogenic disturbance. A total of 24 potential metrics were examined for each of four vegetation zones at the study sites. Of these, 14 successfully discriminated between sites and were used to generate a preliminary index of biotic integrity (IBI) for Lake Huron coastal wetlands. This IBI was then tested by assessing coastal wetlands, including five additional sites, based on invertebrate data collected the following year. The preliminary IBI seemed to provide an accurate depiction of the wetlands used to generate the IBI as well as the five additional wetlands. We do not recommend use of the presented IBI as the definitive assessment tool for Lake Huron coastal wetlands. Instead, we suggest that it be tested further on a series of wetlands with known degrees of anthropogenic disturbance.