Potential Climate and Land Use Change Effects on Brook Trout in the Eastern United States

Open Access
Author:
Deweber, Jefferson Tyrell
Graduate Program:
Wildlife and Fisheries Science
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
June 16, 2014
Committee Members:
  • Tyler Wagner, Dissertation Advisor
  • C Paola Ferreri, Committee Member
  • Douglas Alan Miller, Committee Member
  • William David Walter, Committee Member
Keywords:
  • brook trout
  • river habitat
  • climate change
  • water temperature
  • thermal suitability
Abstract:
Brook Trout is a socially, economically and ecologically important species throughout its native range in the eastern U.S. that is expected to be negatively affected by climate and land use change. In this dissertation, I use publicly available data to identify the potential effects of projected climate and land use change on river water temperature and Brook Trout populations in individual stream reaches throughout the eastern U.S. In Chapter 1, I quantitatively assessed the representativeness of stream flow and water temperature data from U. S. Geological Survey (USGS) gages throughout subregions of the conterminous United States, including the eastern U.S. In Chapter 2, I developed a model to predict river water temperatures under current conditions and future scenarios of climate and land use change. The final model included air temperature, landform attributes and forested land cover, and predicted mean daily water temperatures with good accuracy (root mean squared error ~ 1.9 °C) for training and validation datasets. In Chapter 3, I predicted Brook Trout occurrence probability based on water temperature predictions and selected landscape characteristics using a hierarchical logistic regression model that performed well at both training and validation datasets (area under the receiver operating curve ~ 0.78). In Chapter 4, I identified potential changes in thermal habitat and Brook Trout occurrence probability resulting from projected climate and land use change. The timing, magnitude and location of predicted changes in maximum 30 day mean river water temperature varied greatly among three downscaled climate models, with average increases ranging from 1.21 to 2.55 °C by 2087. As a result of warming, between 56,440 (42.7%) and 109,237 (82.6%) of potential Brook Trout habitat was predicted to be lost. Land use change was predicted to result in localized increases in river water temperature and losses of 4.5% of potential Brook Trout habitat. Given the magnitude of predicted losses, conservation actions will likely be more successful in the long term if the potential changes resulting from climate and land use change are incorporated into the planning process.