Global Amphibian Declines, Disease, and the Ongoing Battle between Batrachochytrium Fungi and the Immune System

In the approximately 30 years since the recognition of the crisis of global amphibian declines, much has been learned about the likely causes. Among the leading causes are several amphibian diseases including the disease termed chytridiomycosis caused by the chytrid fungi Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal). Here, I briefly review the fundamentals of amphibian immunity, amphibian immune defenses against the chytrid fungi, and the host–pathogen interactions that often favor the pathogen to the detriment of the host. Because amphibians are ectotherms, climate and temperature have a major impact on the amphibian immunity. Thus, I discuss current information about the role that temperature and unpredictable weather events may play in disease and immune responses to the chytrids. Because much research on amphibian declines is directed toward finding management solutions to protect threatened amphibians, I conclude by drawing attention to some of the most promising and novel mitigation strategies that are being proposed.