CUR - The Council on Undergraduate Research

Environmental Variables Regulate Prevalence of Batrachochytrium dendrobatidis Infections in California Amphibian Populations

Margaret P. Paulsen, Wynne E. Moss, Brendan K. Hobart, and Dr. Pieter T. Johnson, Ecology and Evolutionary Biology Department, University of Colorado at Boulder, 1900 Pleasant St, Boulder, CO 80302

The emergence and global spread of the pathogenic chytrid fungus Batrachochytrium dendrobatidis (Bd) is a major threat to amphibian biodiversity. In regions where the disease is endemic, the environmental mechanisms regulating infection severity are not well understood. The goal of our study was to better understand how variation in local environmental conditions impacts Bd prevalence in a region where the disease is endemic (California’s East Bay Region). We used field survey data compiled in 2019, consisting of infection data for multiple amphibian species from 75 ponds. We applied generalized linear mixed models to quantify the relationship between Bd prevalence and environmental variables related to climate, water chemistry, and land use for two abundant species captured in our study area: Pseudacris regilla and Anaxyrus boreas. Our findings suggest that pH, air and water temperature, and developed land cover had the strongest effects on disease prevalence in populations of A. boreas and P. regilla in this region. Furthermore, the models indicated that Bd infection in the two species did not respond equally to the environmental variables that were included in the full model, with disease prevalence in A. boreas being more heavily influenced by climate (air temperature and vapor pressure deficit) while prevalence in P. regilla was more responsive to pond conditions (pH, depth, and water temperature). Future studies and policies must take these differences into account when developing effective strategies for managing the disease at each pond. 

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