Meeting Abstract

P3.39  Thursday, Jan. 6  Does iron play a role in the dynamics of an emerging infectious disease? ZILLMANN, A.M.*; COLLINS, J.P.; SMITH, V.H.; Arizona State University; Arizona State University; University of Kansas adrienne.zillmann@asu.edu

Chytridiomycosis is an emerging infectious disease caused by the fungus Batrachochytrium dendrobatidis (Bd) that is implicated in the decline and extinction of numerous amphibian species. The contemporaneous emergence of several wildlife diseases in addition to chytridiomycosis suggests that a common trigger may be sparking an increase in disease incidence across taxa. Anthropogenic disturbance (e.g., nutrient loading) is one type of stimulus that could act simultaneously across wide temporal and spatial scales. We hypothesized that iron (Fe) enrichment of aquatic ecosystems influences chytridiomycosis dynamics because Fe is a trace element that (a) accumulates in sediments that are consumed and incorporated by amphibian larvae, (b) is a source of resource competition between pathogens and hosts, and (c) is correlated with increased growth of Bd in culture. To test this hypothesis we collected 180 American bullfrog (Lithobates catesbianus) tadpoles and classified them as naturally infected or uninfected. Infected animals had greater mass and longer snout-vent lengths (SVL), but did not differ in developmental stage relative to uninfected tadpoles. In the lab, these tadpoles were then exposed to one of three ecologically relevant sediment Fe levels for seven weeks in a factorial experimental design. Changes in tadpole mass, SVL, and developmental rate, as well as differences in immune response, oxidative stress levels, and final parasite load between the treatments were assessed. Our results provide the first comprehensive examination of the role of Fe in the dynamics of an emerging wildlife disease of broad relevance.