Original Research ArticleResponse of benthic macroinvertebrate communities to climate change

Aquatic ecosystems are impacted by climate change. However, the level of impacts, especially on macroinvertebrates, are not well known, which is the goal of this study. Here, three biotic indices were used. The Saginaw River Basin, the largest watershed in Michigan was selected for this study. Since no know modeling package exists to evaluate the impacts of climate change on these biotic indices, a coupled modeling approach was proposed. First, the Soil and Water Assessment Tool (SWAT) was setup to estimate streamflow and water quality for all stream segments. Next, the results from the SWAT model in combination with long-term biological monitoring data were used to develop biotic indices predictive models using a two-phase approach. An assemblage of 42 climate scenarios (2040-2060) were obtained from the National Aeronautics and Space Administration, which are biased corrected and statistically downscaled. The dataset provides two extreme Representative Concentration Pathways (RCPs) to account for best (RCP 4.5) and worst (RCP 8.5) case scenarios. The climate data were incorporated in SWAT and biotic indices predictive models to understand stream health conditions in the watershed. Results showed that the majority of streams have a probability of declining in values of biotic indices while streams that currently have excellent conditions are the most vulnerable streams to the climate change. This modeling approach provides a new mean to link more strongly biota indicators with flow regime indicators, which is of prime interest for the implementation of ecohydrology principles.