Evaluating bromeliads as environmental reservoirs for Batrachochytrium dendrobatidis and amphibian disease dynamics in equatorial forests

Abstract The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) is widely distributed across tropical ecosystems, yet the microhabitats that facilitate its environmental persistence remain poorly understood. We evaluated Bd detection in bromeliad tank contents and infection in amphibian communities across an elevational gradient in Ecuadorian forests. We sampled amphibians at eight sites using skin swabs, and canopy and subcanopy bromeliads at five sites using eDNA. Overall, Bd prevalence was 23.0% in amphibians and 11.3% in bromeliads. Subcanopy bromeliads showed a significantly lower probability of Bd detection than amphibians, whereas canopy bromeliads did not differ significantly from amphibians or subcanopy bromeliads. Mid-elevation sites showed a higher probability of being Bd-positive compared with high-elevation sites, while low-elevation sites did not differ significantly. Amphibian Bd prevalence also increased with precipitation and followed a nonlinear relationship with temperature, suggesting higher prevalence under intermediate thermal conditions. By contrast, Bd detection in bromeliads was not significantly associated with abiotic factors. Bd infection intensity among amphibians did not differ significantly across host taxonomy or sampling sites. Together, these results suggest that bromeliad tanks may provide aquatic microhabitats for Bd detection and short-term persistence, but host infection patterns appear more associated with amphibian taxonomic identity, site-level variation and local climatic conditions.