Sick to Death
This chapter begins with screening Crawfish Frogs for chytrid fungus and Ranavirus infections. Vance Vredenburg and his colleagues have suggested that a zoospore equivalent of approximately 10,000 triggers the disease chytridiomycosis and death in amphibians. Drought does, however, have occasional beneficial ecological effects for amphibians. Drawn-down seasonal and semi-permanent wetlands lose their fish and invertebrate fauna; absent these predators, tadpoles can thrive. To this ecologic benefit of drought, we suggested another—that drought can reduce Batrachochytrium dendrobatidis (Bd) infection intensities, and therefore decrease the incidence of amphibian deaths due to chytridiomycosis. Ranaviruses represent a subset of iridoviruses that infect not only amphibians, but also reptiles, especially turtles, and fishes. The antimicrobial properties of Crawfish Frog skin-gland secretions may facilitate shedding Bd infections. As they overwinter, about a quarter of Crawfish Frogs then reacquire Bd spores from the cool, moist walls of the burrow or the water in the chamber at its base.