Batrachochytrium dendrobatidis (Bd) in American bullfrogs: Assessing the role of bullfrogs as a pathogen reservoir in California's Bd-endemic ponds Public

Abstract

American bullfrogs (Lithobates catesbeianus) are listed on the International Union for Conservation of Nature’s (IUCN) list of 100 worst invasive species in part because they have facilitated the spread of Batrachochytrium dendrobatidis (Bd), an emerging fungal pathogen, around the globe. However, the role of bullfrogs in facilitating Bd persistence as a reservoir species in endemic systems remains unclear. In order to elucidate the relationship between bullfrogs and Bd persistence, I used 11 years of field surveys on 9 ponds in California’s East Bay Region as well as to test three assumptions of competent reservoirs: (1) bullfrogs have high infection prevalence and intensity, (2) bullfrogs do not experience mortality from Bd infections, and (3) overwintering bullfrog tadpoles are able to sustain Bd infections and therefore serve as a between-season maintenance host. My results provide some support for assumptions one and three, and tenuous support for assumption two. Together, these findings indicate that bullfrogs might be competent reservoirs of Bd in certain life stages and environments but might not be as competent a Bd reservoir as initially thought. Further study is needed to understand the relationship between invasive species and Bd ecology in order determine if interventions like invasive species removal are effective Bd disease control strategies. 

Table of Contents

Introduction………………………….…………………………..………………………….…..…1

Methods…………………………..…………………………..……………………………………5

            Field Collection…………………………..…………………...……………………..……5

            Bd Detection and Quantification…………………………..…………………………..….7

            Data Visualization and Analysis...……………………..…………………………..…..….7

Results…………………………..…………………………..……………………………………10

Discussion…………………………..…………………………..……………………..…………13

            Assumption 1…………………………..…………………………………………………13

            Assumption 2…………………………..…………………………………………………14

            Assumption 3…………………………..…………………………………………………16

            Conclusions…………………………..…………………………………………………..17

References…………………………..…………………………..………………………………..19

Appendix…………………………………………………………………………………………23

About this Honors Thesis

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School	Emory College
Department	Environmental Studies
Degree	B.S.
Submission	Honors Thesis
Language	English
Research Field	Environmental Sciences Biology, Parasitology Biology, Ecology
Mot-clé	Disease ecology chytrid American bullfrog Bd amphibian
Committee Chair / Thesis Advisor	Dr. David Civitello, Emory University
Committee Members	Dr. Gonzalo Vasquez Prokopec, Emory University Dr. Carolyn Keogh, Emory University

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