Metabolites produced by Batrachochytrium dendrobatidis alter development in tadpoles, but not growth or mortality

The mass decline of amphibian populations poses a serious threat to global biodiversity and ecosystem stability. The pathogenic fungus Batrachochytrium dendrobatidis (Bd) has contributed to the extirpation and extinction of hundreds of amphibian species worldwide. Bd produces potentially damaging metabolites during the host infection process that may affect amphibian growth and development, even in the absence of infection. In this experiment, Cuban tree frog Osteopilus septentrionalis tadpoles and adults were exposed once to either artificial spring water (ASW) or Bd metabolites (n = 31 tadpoles per treatment and n = 30 and 20 adults per treatment, respectively). Tadpoles exposed to Bd metabolites alone developed faster than those exposed to ASW; however, there was no difference in tadpole length, weight change, or mortality between treatments. Despite the faster developmental speed, metabolite exposure did not reduce tadpole weight or length (compared at Gosner stages 27, 29, and 31). There was no effect of treatment on adult size or mortality. These results indicate that both tadpole and adult O. septentrionalis do not appear to be negatively impacted by exposure to non-infectious Bd-contaminated water. In fact, tadpoles developed faster when exposed to metabolites and were of equal size as those in their stage cohort, implying a potential long-term benefit if faster development allows them to leave Bd-infected waters sooner.