The role of the geophysical template and environmental regimes in controlling stream-living trout populations

Authored by Steven F Railsback, Jason B Dunham, Brooke E Penaluna, Robert E Bilby, Arne E Skaugset, Sherri Johnson

Date Published: 2015

DOI: 10.1139/cjfas-2014-0377

Sponsors: United States Geological Survey (USGS) U.S. Environmental Protection Agency's Science to Achieve Results (STAR) American Fisheries Society Watersheds Research Cooperative

Platforms: No platforms listed

Model Documentation: Other Narrative

Model Code URLs: Model code not found

Abstract

The importance of multiple processes and instream factors to aquatic biota has been explored extensively, but questions remain about how local spatiotemporal variability of aquatic biota is tied to environmental regimes and the geophysical template of streams. We used an individual-based trout model to explore the relative role of the geophysical template versus environmental regimes on biomass of trout (Oncorhynchus clarkii clarkii). We parameterized the model with observed data from each of the four headwater streams (their local geophysical template and environmental regime) and then ran 12 simulations where we replaced environmental regimes (stream temperature, flow, turbidity) of a given stream with values from each neighboring stream while keeping the geophysical template fixed. We also performed single-parameter sensitivity analyses on the model results from each of the four streams. Although our modeled findings show that trout biomass is most responsive to changes in the geophysical template of streams, they also reveal that biomass is restricted by available habitat during seasonal low flow, which is a product of both the stream's geophysical template and flow regime. Our modeled results suggest that differences in the geophysical template among streams render trout more or less sensitive to environmental change, emphasizing the importance of local fish-habitat relationships in streams.

Tags

individual-based models ecosystems landscape ecology habitat Fish Cutthroat trout River continuum concept Thermal requirements Pacific-northwest Salmonids