The last Rabbs’ tree frog died exactly a year ago.
To mark this anniversary of the extinction of the Rabbs’ tree frog, this post will explore the origins, ecology and potential solutions to the problem of chytrid fungus. Before its extinction, wild populations of the frog were decimated by the fungus.
Chytrid fungus (Batrachochytrium dendrobatidis) is thought to have originated from Africa, and spread to other regions via the pet trade. It is now found in six continents. Although B. dendrobatidis has a complex evolutionary history, it started infecting amphibians relatively recently. Therefore, it is considered to be an emerging pathogen.
Despite its devastating effects in terrestrial ecosystems, chytrid fungus may play an important role in aquatic ecosystems. For example, they are thought to decompose organic matter and be a food source for zooplankton.
Transmission of B. dendrobatidis occurs during its free-swimming flagellated zoophore stage. Each zoophore can swim at speeds of up to 2cm/day. At this point in the life cycle of the fungus, microorganisms such as water fleas may consume it.
After its free-swimming stage, the zoophore becomes substrate dependent. This may happen after infecting a host, and is the reproductive stage of the fungus’ life cycle. Chytrid fungus can infect both adults and juveniles, and further research into its pathogenesis is needed.
Despite the gloomy outlook from the world of amphibian conservation, all is not lost. Treatments such as heat therapy and antifungal drugs are being developed, with the aim of eradicating chytrid from amphibian populations.
Research suggests that in order for treatment to be effective, multiple lines of attack will be needed. As our knowledge of this fungus increases, our ability to lessen its devastating effects on amphibian populations may improve.
In the meantime, we can continue to admire and support the work of place like the El Valle Amphibian Conservation Centre.
References
Freshwater ecosystems and chytrid
Barreleye Zoology 