Stream tadpoles present high prevalence but low infection loads of Batrachochytrium dendrobatidis (Chytridiomycota)

Abstract

Tadpoles can be found in different lentic and lotic habitats, including permanent and ephemeral water bodies. Characteristics from these habitats influence both the tadpole assemblages and the co-occurring amphibian-killing fungus Batrachochytrium dendrobatidis (Bd). However, this intricate relationship has not been fully addressed. Bd causes depigmentation of tooth rows and jaw sheaths, but infection is usually nonlethal in tadpoles. We herein investigate how Bd interacted with tadpoles from different habitats in a high elevation site in the Brazilian Atlantic forest. Our results revealed that Bd was more prevalent in tadpoles from lotic habitats (streams) as expected, even though the infection intensity was greater in tadpoles from lentic habitats (ponds), especially on those sampled in permanent ponds. Also, because tadpoles may act as Bd reservoirs, influencing the infection rates of adult amphibians, we hypothesized that at sites where Bd was very prevalent on tadpoles, it would also be very prevalent on adults. However, we did not find such interaction. Even so, Bd has the potential to rapidly spread in water and understanding its dynamics in this environment could be the key to prevent die-offs events, already reported from amphibian populations worldwide.