Local variability mediates vulnerability of trout populations to land use and climate change

PLoS ONE
By: , and 

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Abstract

Land use and climate change occur simultaneously around the globe. Fully understanding their separate and combined effects requires a mechanistic understanding at the local scale where their effects are ultimately realized. Here we applied an individual-based model of fish population dynamics to evaluate the role of local stream variability in modifying responses of Coastal Cutthroat Trout (Oncorhynchus clarkii clarkii) to scenarios simulating identical changes in temperature and stream flows linked to forest harvest, climate change, and their combined effects over six decades. We parameterized the model for four neighboring streams located in a forested headwater catchment in northwestern Oregon, USA with multi-year, daily measurements of stream temperature, flow, and turbidity (2007–2011), and field measurements of both instream habitat structure and three years of annual trout population estimates. Model simulations revealed that variability in habitat conditions among streams (depth, available habitat) mediated the effects of forest harvest and climate change. Net effects for most simulated trout responses were different from or less than the sum of their separate scenarios. In some cases, forest harvest countered the effects of climate change through increased summer flow. Climate change most strongly influenced trout (earlier fry emergence, reductions in biomass of older trout, increased biomass of young-of-year), but these changes did not consistently translate into reductions in biomass over time. Forest harvest, in contrast, produced fewer and less consistent responses in trout. Earlier fry emergence driven by climate change was the most consistent simulated response, whereas survival, growth, and biomass were inconsistent. Overall our findings indicate a host of local processes can strongly influence how populations respond to broad scale effects of land use and climate change.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Local variability mediates vulnerability of trout populations to land use and climate change
Series title PLoS ONE
DOI 10.1371/journal.pone.0135334
Volume 8
Issue 10
Year Published 2015
Language English
Publisher PLoS
Contributing office(s) Forest and Rangeland Ecosystem Science Center
Description e0135334: 20 p.
Country United States
State Oregon
Other Geospatial Gus Creek, Pothole Creek, Rock Creek, Upper Mainstem Trask
Online Only (Y/N) N
Additional Online Files (Y/N) N