Understanding the Role of Climate Change and Land Use Modifications in Facilitating Pathogen Invasions and Declines Of EctothermsEPA Grant Number: R833835
Title: Understanding the Role of Climate Change and Land Use Modifications in Facilitating Pathogen Invasions and Declines Of Ectotherms
Investigators: Rohr, Jason R. , Raffel, Thomas R. , Blaustein, Andrew
Institution: University of South Florida , Oregon State University
EPA Project Officer: Packard, Benjamin H
Project Period: September 1, 2008 through August 31, 2011 (Extended to August 31, 2013)
Project Amount: $599,353
RFA: Ecological Impacts from the Interactions of Climate Change, Land Use Change and Invasive Species: A Joint Research Solicitation - EPA, USDA (2007) RFA Text | Recipients Lists
Research Category: Global Climate Change , Aquatic Ecosystems , Ecosystems , Climate Change
Invasive parasites of humans and wildlife are arising at an unprecedented rate and are debilitating our ecosystems. For instance, pathogens have been implicated in many amphibian declines that are triggering state changes and impairing ecosystem functions. Climate change and land use modifications might elicit disease emergence, but few generalizations have materialized for how these factors facilitate parasite invasions. We recently documented immuno-suppression in amphibians associated with agrochemical exposure and temporal climatic variability, stimulating the agrochemical spread and climatic variability hypotheses. These hypotheses predict that proximity to agriculture (a global land-use modification) and elevated temporal variability in temperature (due to climate change), respectively, compromise host immunity and facilitate parasite invasions. In our preliminary work, both temperature increases and decreases caused suboptimal immunity, but drastic seasonal drops in temperature caused the longest periods of suboptimal immunity, stimulating the hypothesis that cold-tolerant parasites will benefit most from elevated climatic variability driven by global climate change. We propose to test these hypotheses on multiple parasites and ectothermic taxa, but intentionally focus on the invasive Batrachochytrium dendrobatidis and amphibians because this emerging chytrid fungus is cold-tolerant and implicated in many of the global amphibian declines.
We will test our hypotheses by 1) examining whether the timing of apparently disease-induced amphibian extinctions in Central and South America are related to climatic variability, proximity to agriculture, or alternative factors, 2) testing whether the distribution of extinct and threatened ectothermic species worldwide is positively associated with the spatial pattern of climatic variability and agriculture across the globe, and 3) conducting a series of manipulative experiments in which we will expose numerous ectothermic hosts and cold- and warm-tolerant parasites to constant and variable temperatures (across a temperature range) and quantify subsequent host immunity and parasite infections.
We expect to reveal general mechanisms by which climate change and specific land use modifications facilitate parasite invasions. This will enhance risk assessment and management by allowing decision makers to prioritize regions, localities, and species that are at risk for potentially debilitating parasite invasions.