Leaf Litter Leachate Limits Fungal Pathogen Growth but Not Amphibian Infection

Area of Science:

• Ecology
• Environmental Science
• Amphibian Pathology

Background:

• Terrestrial leaf litter releases chemical compounds into aquatic ecosystems, forming leachates.
• These leachates can impact freshwater organisms and influence ecological dynamics.
• The fungal pathogen *Batrachochytrium dendrobatidis* (Bd) causes chytridiomycosis, a devastating disease in amphibians.

Purpose of the Study:

• To investigate the direct effects of six plant species' leaf litter leachates on *Batrachochytrium dendrobatidis* (Bd) in vitro.
• To assess the impact of these leachates on tadpole susceptibility to Bd infection in vivo.
• To understand the role of terrestrial inputs in freshwater ecosystems on amphibian health.

Main Methods:

• In vitro assays to quantify Bd zoosporangia and zoospores exposed to varying leachate concentrations.
• In vivo experiments exposing tadpoles to leachates before and during Bd exposure.
• Monitoring of tadpole survival, growth, development, and infection levels.

Main Results:

• All six leaf litter leachates reduced Bd zoosporangia concentration in vitro.
• Purple loosestrife leachate exhibited the strongest inhibitory effect on Bd.
• Leachate concentration positively correlated with negative impacts on Bd in vitro.
• No significant effects of leachates on tadpole survival, size, development, or Bd infection were observed in vivo.

Conclusions:

• Leaf litter leachates possess direct antifungal properties against Bd in laboratory settings.
• The direct antifungal effects of leachates do not necessarily translate to protection against Bd infection in tadpoles.
• Further research is needed to elucidate the complex interactions between leaf litter leachates, Bd, and aquatic amphibians in natural environments.
• Understanding terrestrial-aquatic linkages is crucial for amphibian conservation efforts.