Development of a comprehensive framework to assess the impacts of climate change on stream health

Abstract

Extended Abstract. Anthropogenically-driven climate change is projected to alter water resources and thereby impact behavior of aquatic ecosystems. Changes in hydrology and increased magnitudes of nonpoint source pollution concentrations negatively impact stream integrity, such as fish and macroinvertebrate health. While it is imperative to understand the consequences of climate change on aquatic ecosystem health, it is also necessary to identify the quantitative risk of degradation. By recognizing the risk of adverse impacts to aquatic ecosystem health locally and regionally, adaptation strategies can be prioritized. This study quantifies the potential impacts of changing climate on aquatic ecosystem integrity by coupling climate models, a watershed/water quality model, and ecological models. Bias-corrected daily climate data from multiple global climate models (GCMs) was used with a high-resolution Soil and Water Assessment Tool (SWAT) to characterize future flow regime and water quality for multiple Michigan watersheds. In-stream flow regime and water quality variables were then used to develop models of fish and macroinvertebrate health based on biological sampling data. These health measures were the fish Index of Biological Integrity (IBI), Hilsenhoff Biotic Index (HBI), Family IBI, and total number of Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxa. Stream health model development was performed using adaptive neuro-fuzzy inference systems (ANFIS). Best models were selected by their ability to predict each stream health measure at biological sampling locations, and were then extended beyond monitoring points to all watershed reaches. Through the use of several GCMs, emissions scenarios, and stream health measures, we develop multiple projections for the risk of degraded stream health due to climate change at reach and watershed scales.