Meeting Abstract
As the climate changes, warmer temperatures are expected to increase the rate at which ephemeral ponds dry, which will likely have consequences for amphibians. Reduced hydroperiods can influence larval growth and developmental rates and might also impact amphibian characteristics post-metamorphosis, such as immune function and disease susceptibility. We predicted that as ponds dry faster, (1) tadpoles would metamorphose quicker but at a smaller size, and (2) metamorphosed frogs would have reduced immune function and be more susceptible to disease. We tested these predictions by raising northern leopard frogs (Lithobates pipiens) in mesocosms assigned to one of four drying treatments: no-, slow-, medium-, and fast-drying. After frogs metamorphosed, we repeatedly exposed a subset of animals to Batrachochytrium dendrobatidis (Bd) and measured immune function in another subset of animals. Contrary to our first prediction, drying rate alone had no effect on development time or size at metamorphosis. In metamorphosed frogs, drying rate did not affect Bd load in our exposure experiment or T-cell response. However, T-cell response increased with larval period regardless of drying treatment, indicating that a longer larval period can be beneficial post-metamorphosis. Furthermore, frogs in the slow-drying treatment had a greater B-cell response than those in the medium-drying treatment, showing that some effects of reduced hydroperiod experienced in the larval period can persist post-metamorphosis. Taken together, our results show that the effects of pond drying rates on amphibians are not straightforward and require further study.
