The Response of Benthic Macroinvertebrate Communities to Climate Change within the Saginaw River Watershed

Abstract

Abstract. Climate change can have strong effects on aquatic ecosystems. Temperature change as an example, will influence abundance and timing of species in many ways. Meanwhile, flow regime dynamics, such as minimum flows, affect macroinvertebrate assemblages. Macroinvertebrate monitoring is a common approach to evaluate the freshwater quality variation. However, due to large cost of associated with biomonitoring, it is difficult to perform in a large scale. In this study, three macroinvertebrates indices, the Index of Family Biological Integrity (IBI), Hilsenhoff Biotic Index (HBI), and total number of Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxa, are used to evaluate stream health conditions within the Saginaw River Watershed. The Saginaw River watershed is the main six digit Hydrologic Unit Code watershed in Michigan, which has the largest number aquatic biomonitoring sites in the state. The Soil and Water Assessment Tool (SWAT) model was calibrated and validated for this watershed to estimate flow regime dynamics and water quality conditions in about 14,000 stream segments. The results of the SWAT model was used to develop biological models to predict macroinvertebrates indices. The climate data was obtained from the Coupled Model Intercomparison Project Phase 5 (CMPI5) and four different realizations (ECHam, HadCM3, CCSM and CSIRO) were evaluated in the SWAT and biological models to account for climate change variability and uncertainty. Outputs from the hybrid modeling exercise can be helpful in determining the impact of climate change on macroinvertebrate communities.