Predicting Effects of Climate Change on Native Fishes in Northern Great Plains Streams

Science Center Objects

The Northern Great Plains of North America are a region of profound global importance because organisms that live in these semi-arid prairie environments have developed a unique ability to live through conditions of extreme heat, cold, floods, and drought. Prairie streams are essential components of these ecosystems because they provide critical “green lines” of habitat for both aquatic and terrestrial wildlife. The fish that inhabit the warm, turbid waters of these streams are indicators of change in these delicate ecosystems, where water quantity and water quality are often precariously close to ecological tolerance limits. In fact, changes in water quantity and quality associated with global climate change may transform prairie streams from essential refuges to habitats no longer capable of supporting fishes. USGS researchers and their partners are studying these changes and developing tools to assist managers in predicting the effects of climate change on prairie stream ecosystems of the northern Great Plains.

Stream sampling in eastern Montana.

Researchers are linking predicted changes in precipitation and air temperature to changes in timing and quantity of flow in streams, and in turn, fish assemblages (i.e. groups of fish in a specific area). Hydrology can be linked to fish assemblages using watershed characteristics such as area, topography, and land cover. For instance, streams in larger watersheds generally have more runoff and sustain longer flows than streams in smaller watersheds and also support more fish diversity. Because of this link between hydrology and biology, researchers can use watershed area as well as other watershed characteristics to describe current hydrological and biological conditions, as well as predict changes under future climate conditions. Specific methods include:

  • Construct watershed models that simulate daily streamflow using temperature and precipitation inputs for two stream networks in Montana. For the modeled watersheds and 5-7 other watersheds, link duration and magnitude of flows to watershed characteristics such as area, topography, and land cover based on current climate conditions. l PROJECT PAGE l
  • Develop a regional model of fish assemblage structure as a function of watershed characteristics using a database of over 1,600 fish collections from Montana prairie streams to serve as a baseline of current conditions.
  • Predict how hydrology and fish assemblages will be affected using the watershed models and projected changes in precipitation and temperature from the RegCM3 regional climate model (available at http://regclim.coas.oregonstate.edu)
  • Use projected climate conditions to predict where changes in fish assemblages will occur, relative to the current levels of biological integrity (Index of Biotic Integrity or IBI) for the samples in the regional fish database. This will allow researchers to identify areas of primary conservation concern and compare them to the areas that are most likely to undergo changes as a result of climate change.
Map of stream sampling sites in eastern Montana.

 

Management Benefits

Fisheries and resource managers will be provided with information regarding current and potential future conditions of prairie stream ecosystems. This information can be used to help focus conservation and restoration efforts in the northern Great Plains. Information related to changes in timing and quantities of streamflow will be useful to agencies and stakeholders such as watershed conservation groups, ranchers, and others that rely on or work near prairie streams. This project is also providing information to help preserve prairie fish species and their habitat, ultimately benefiting the entire prairie ecosystem and the communities in the northern Great Plains.

 

This project was funded by the Plains and Prairie Potholes Landscape Conservation Cooperative and the Bureau of Land Management.