Predation by zooplankton on Batrachochytrium dendrobatidis: biological control of the deadly amphibian chytrid fungus?

Batrachochytrium dendrobatidis (hereafter Batrachochytrium), a fungal pathogen of amphibians, causes the disease chytridiomycosis which is responsible for unprecedented population declines and extinctions globally. Host defenses against chytridiomycosis include cutaneous symbiotic bacteria and anti-microbial peptides, and proposed treatment measures include use of fungicides and bioaugmentation. Efforts to eradicate the fungus from localized areas of disease outbreak have not been successful. Instead, control measures to mitigate the impacts of the disease on host populations, many of which are already persisting with Batrachochytrium in an endemic state, may be more realistic. The infective stage of the fungus is an aquatic zoospore, 3-5 mu m in diameter. Here we show that zoospores of Batrachochytrium are consumed by the zooplankter Daphnia magna. This species inhabits amphibian breeding sites where Batrachochytrium transmission occurs, and consumption of Batrachochytrium zoospores may lead to effective biological control of Batrachochytrium.