Meeting Abstract
The proximate cause of wide-spread amphibian death following infection with chytrid fungus (Batrachochytrium dendrobatidis– Bd) has been reported as a loss of organismal osmotic regulation, leading to cardiac arrest. More recently, earlier changes in gene expression have been detected, indicating that organismal function might be compromised more quickly after infection than previously expected. No one has examined, to our knowledge, how or if metabolic rate changes during the time course of Bd infection. We infected adult Cuban tree frogs (Osteopilus septentrionalis) with Bd and measured whole animal metabolic rate during the time course of a six-week infection. Exposure to Bd resulted in a rapid loss of metabolic rate following just eight days of infection, with continued loss of metabolic rate as the infection progressed up to six weeks. Additionally, we observed possible evidence of changes to host stress response in these metabolic data. Our interpretation of these data was supported by behavioral experiments in which we assessed the stress response of individuals during the time course of infection. In general, uninfected individuals were more sensitive to stimulus and moved further than uninfected individuals after six weeks of exposure. The early loss of metabolic rate and associated decrease in stress response indicates that amphibian hosts may be impacted earlier in the time course of infection than expected. These physiological changes may leave infected amphibians at elevated risk of negative outcomes as both diminished predators and increasingly susceptible prey.
