The influence of antimicrobial peptides, cutaneous microbial communities and water quality on the susceptibility of Columbia spotted frogs (Lithobates luteiventris) to Chytridiomycosis

Abstract

Chytridiomycosis is a potentially deadly skin disease found in amphibian populations worldwide. The disease is caused by the fungus Batrachochytrium dendrobatidis (Bd) which grows on the skin of amphibians. The fungus can disrupt the homeostatic functions of amphibian skin and can lead to death. An amphibian’s antimicrobial skin secretions, cutaneous microbial communities and the environmental water quality have the potential to influence resistance to Bd infection. However, few studies have examined how these factors interact to impart resistance. Columbia spotted frogs (Lithobates luteiventris) are native to western Montana and can be affected by chytridiomycosis. Three lakes known to be positive for Bd were used as collection sites over the course of the summer of 2018. Each frog was swabbed for bacterial and fungal DNA and the frogs were placed in a solution to collect antimicrobial peptides (AMPs) secreted from the skin. Water samples were collected at each site and analyses were performed to assess various environmental parameters. Early results suggest that AMPs may affect the relative abundance of an important anti-fungal bacteria (Rhizobacter) which influences Bd status. The goal of the ongoing research is to better understand how interactions between skin secretions, cutaneous microbial communities and environmental parameters allow Columbia spotted frogs to resistant chytridiomycosis, and to use this information to better predict and treat future outbreaks.