Climate models for streams in the Mississippi River Basin

Estimates of nutrient loading to the Gulf of Mexico indicate that nine states within the Mississippi River Basin are responsible for approximately 75% of all nitrogen and phosphorus delivered to the Gulf. The Mississippi Basin supports a rich assemblage of fish species; at least 25% of all species in the conterminous United States are found in the Basin. These assemblages reflect their habitats, human landscape disturbances, and fragmentation of the river network by dams. Climate also has close associations with aquatic habitat conditions and ultimately fish community composition. Climate change is anticipated to lead to additional changes in stream habitats, including changing thermal properties and flow regimes. Ultimately, such changes will affect the Gulf, underscoring the importance of addressing upstream impacts.

Accounting for current condition of and future changes in streams and understanding specific mechanisms by which they are or may become impaired are essential for effective management and conservation of stream fishes and their habitats—and will translate into improvements in nutrient loading in waters delivered to the Gulf.

Based on previous work initially developed for the Northeast Climate Science Center in cooperation with the U.S. Fish & Wildlife Service in the FishTail online decision support tool only for Northeast states, this project will expand management and attribution of future climate data to the entire US portion of the Mississippi River Basin to facilitate analyses that will identify changes in fish habitat that may occur with changes in climate as a next step in meeting these needs. The project will consist of the following two tasks:

Task 1. Regionally-downscaled projected climate data are developed for eight CMIP3 global climate models (Delcambre et al. 2013) from throughout the Basin (Notaro et al. 2011) with 19 specific climate variables available for describing facets of air temperature and precipitation. Eight sets of results corresponding to each model indicating potential changes in stream reach class will be developed and averaged for a future time frame (2041-2080). These results will be linked to individual stream reaches of the National Hydrography Dataset V1.

Task 2. Leverage datasets from several projects that were previously conducted to compile additional metrics needed to classify stream reaches including: 1) in-stream temperature and flow metrics within the study region; 2) a variety of flow metrics assembled for hundreds of stream reaches located throughout the study region as part of a recently completed effort funded by the U.S. Geological Survey’s National Climate Change and Wildlife Science Center; and 3) associations between stream fishes and temperature and flow metrics that were identified to develop a list of thermal and flow sensitive fish species throughout the study region.

Products from this work will be attributed to a consistent and comprehensive spatial coverage of rivers from throughout the basin previously developed from the National Hydrography Dataset Plus Version 1 (NHDPlusV1, framework described in Wang et al. 2011) which includes 1:100,000-scale river arcs, as the smallest spatial unit for characterizing stream habitats.