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The importance of location: Responsiveness of stream-living fish populations Brooke Penaluna USFS PNW Research Station Oregon State University Co-authors:

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Presentation on theme: "The importance of location: Responsiveness of stream-living fish populations Brooke Penaluna USFS PNW Research Station Oregon State University Co-authors:"— Presentation transcript:

1 The importance of location: Responsiveness of stream-living fish populations Brooke Penaluna USFS PNW Research Station Oregon State University Co-authors: S. Railsback, J. Dunham, S. Johnson, A. Skaugset, and R. Bilby

2 Trask Watershed Fish component: multiple lines of inquiry

3 Location within landscape matters

4 Stream flow Stream temperature Turbidity Nutrients Stream gradient Stream shape Habitat units Velocity shelter Hiding cover Spawn gravel Habitat template Environmental regimes Headwater streams are ideal to study location-related processes

5 Headwater streams can be quite different Pothole Rock Upper Mainstem (UM) Gus Trask River Watershed

6 Trout demography is unique to each site

7 1)What is the spatial variability of fish population biomass across headwater streams? 2) What is the role of environmental regimes and the habitat template to fish population biomass? Habitat template Environmental regimes

8 Using an Individual-based Model to understand complex interactions 1)Individuals grow and change 2)Variability among individuals of same age 3) Resources used by individuals reflect availability 4) Population abundance is based on field data Goal: to compare fish biomass to observed patterns from field Grimm and Railsback 2005 individuals population community

9 inSTREAM model individual behavior population responses Environmental Regimes Stream temperature, flow, and turbidity Habitat template Channel shape, velocity shelter, hiding refuge, and spawn gravel

10 1)What is the spatial variability in fish population biomass across headwater streams?

11 Headwater streams from same watershed can have very different population biomass densities

12 Headwater streams have significantly distinct fish responses Biomass data using 5 age classes Transform: square root Resemblance: Euclidean distance 4 years x 2 seasons = 8 points per site All pairwise comparisons significant P<0.05 Higher biomass Lower biomass

13 Fish populations differ even within a few hundred meters within the same watershed But, what are these differences due to? Fixed habitat template or dynamic environmental regimes?

14 Gus Rock Pothole Upper Mainstem Gus Rock Pothole Upper Mainstem 2) What is the role of environmental regimes and the habitat template to fish population biomass? Habitat template Environmental regimes

15 Even with differing environmental regimes fish populations maintain similar responses

16 Habitat template controls fish response Higher biomass Lower biomass 4 years x 2 seasons x 4 sites = 32 points per site All pairwise comparisons significant P<0.05

17 Next step: examine alternative scenarios Stream flow Stream temperature Turbidity Nutrients Stream gradient Stream shape Habitat units Velocity shelter Hiding cover Spawn gravel Habitat template Environmental regimes Forest harvest Climate change

18 Conclusions Fish populations among headwater streams respond differently to same factors because the habitat template controls fish responses Headwater streams with higher heterogeneity in their habitat template also had higher fish biomass This may suggest that certain headwater streams may be more sensitive than others to changes in environmental regimes from climate change or forest harvest

19 Acknowledgements Funding sources: EPA STAR grant, USGS FRESC, Trask Watershed Study OSU graduate school and FW departmental scholarships, AFS scholarships, USFS PNWwww.watershedsresearch.org PhD committee: Jason Dunham, Steve Railsback, Sherri Johnson, Lisa Ganio, Matt Betts, Jim Hall Field help: Boyd Carroll, Ben Ramirez Graphics help: Kathryn Ronnenberg, Ivan Arismendi


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