Integrated Ecohydrological Science in the Northern Rocky Mountains — the variability of water availability and the effects on ecosystems

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Our primary goal is to better understand and characterize how stream environments and the ecosystems they support are influenced by climate change and drought in the Northern Rocky Mountains.

A New Path to Assess Drought Impacts and Improve Conservation across the United States

Drought events are increasing in severity and extent across many regions of the United States, posing a critical threat to humans and natural ecosystems. To better manage and improve the resilience of our Nation’s communities and ecosystems, the USGS developed a USGS Integrated Drought Science Plan that calls for coordinated and integrated approaches to drought science and outlines a new path towards understanding drought impacts on society and ecosystems. Researchers are striving to advance critical information necessary for decision-makers to take action in the coming decades.

Researchers install a guage station

Researchers install a guage station to examine the effects of drought on the variability of water availability and ecosystems.

(Public domain.)

USGS scientists launched this new ecological drought implementation strategy to advance the Integrated Drought Science Plan in several watersheds across the United States, including the Flathead, Yellowstone, and Snake River basins in the Northern Rocky Mountains. The goal of this study is to link hydrological and biological data to understand how drought affects biota across aquatic environments, from headwater streams to larger rivers and lakes.

Currently, our ability to monitor and model potential changes in streamflow across diverse freshwater systems and habitats is limited by existing monitoring stations that are predominantly focused on large, lower elevation rivers. This is particularly concerning, given that over 100 threatened or endangered aquatic species depend on headwater stream environments, not to mention the numerous ecosystem services generated by headwater streams. We need to focus research and data collection to illuminate exposure, sensitivity, and adaptive capacity (i.e., vulnerability) of aquatic species and communities to drought. This new USGS integrated ecological drought research addresses drought vulnerability across riverscapes to better inform natural-resource conservation and management.

Integrating Drought Research in the Northern Rocky Mountains (NOROCK)

In the Flathead, Yellowstone, and Snake River basins, researchers will address how drought influences streamflow within and among headwater catchments of various stream order (1st, 2nd, and 3rd), and how this variation influences aquatic biota at multiple scales - from genes, to individuals, to populations, and ultimately community dynamics. Research will focus on how drought affects the following areas:

  1. Streamflow in headwater catchments: Researchers will deploy sensors in 60 streams to gather data about streamflow and temperature to characterize inter- and intra-annual variation.
  2. Individual survival and growth: Researchers will gather information on fish length and weight and also track fish movement to understand how inter-annual and seasonal variation in climate – including drought events – influences growth and survival, two critical traits that influence the ecology and evolution of salmonids populations.
  3. Population abundance and genetic diversity: Using long-term data on bull trout abundance, researchers will model temporal patterns in bull trout population dynamics as a function of flow variability and drought vulnerability metrics. Additionally, researchers will collect genetic information on fish to quantify how spatial variation in streamflow and drought sensitivity are related to genomic diversity and evolutionary dynamics in trout.
  4. Aquatic insect and fish community assemblages: Coupling long-term insect monitoring data with stream discharge and temperature will allow researchers to assess the effect of hydrologic and temperature variation on macroinvertebrate community abundance and diversity. Lastly, eDNA samples will be collected at all study locations to describe the surrounding biological community and to quantify how streamflow variation and drought sensitivity within streams is related to measures of biodiversity.
Researchers conduct instream eDNA sampling

Scientists collect an eDNA sample in the water to characterize aquatic and terrestrial species diversity. Researchers conduct instream sampling to examine the effects of drought on the variability of water availability and ecosystems.

(Public domain.)

This project will significantly improve our understanding of ecological responses to drought and our ability to monitor and predict water availability at spatial scales important for aquatic species and ultimately human use. Together, these efforts will greatly enhance the capacity of the USGS in this crucial field while simultaneously benefiting decision-making, leveraging partnerships, informing policy, and addressing urgent stakeholder needs.