A recent lab collaboration on pumpkin toadlets in Brazil's Atlantic Forest revealed a surprising and complex relationship between drought and a deadly waterborne fungus, Batrachochytrium dendrobatidis (Bd). While a short-term, experimental drought directly suppressed the fungus's overall load on the toadlets, it also intensified its transmission. This paradoxical effect occurred because the dry conditions caused the toadlets to congregate in and around remaining water sources, increasing the opportunity for the pathogen to spread from one host to another.
Furthermore, the study led by PhD student Shannon Buttimer from the lab of Gui Becker, found that the drought negatively impacted the toadlets' skin microbiome, a crucial part of their defense against pathogens. The skin of the drought-affected toadlets had a lower proportion of bacteria known to inhibit the Bd fungus, which may have made them more susceptible to infection. These findings highlight a critical point: climate change can affect wildlife health not just through simple cause-and-effect, but through a complex chain of events that alters animal behavior and disrupts their natural defenses, ultimately increasing the risk of disease.
Citation: Buttimer, S., D. Medina, R.A. Martins, A.G. Morais da Silva, W.J. Neely, C.F.B. Haddad, G.V. DiRenzo, A. Catenazzi, R.C. Bell, C.G. Becker. 2025. Experimental drought suppresses amphibian pathogen yet intensifies transmission and disrupts protective skin microbiome. Global Change Biology 31: e70275.
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