Chytrid fungus threat to amphibian biodiversity and disease management strategies

Chitrid Fungus

Chytrid fungus and the local amphibian population: Taking action

A chytrid is a type of fungus found almost exclusively in wet environments, the kind of areas where amphibians such as frogs make their homes. Although it is not specific to Texas, in recent years the chytrid fungus has proven to be a menace to many local amphibian populations. Scientists have found that the chytrid fungus "appears to be capable of infecting most of the world's approximately 6,000 amphibian species and many of those species develop the disease chytridiomycosis which is linked to devastating population declines and species extinctions (Pessier 2010). The presence of the fungus in a local population is cause for alarm given its threat to biodiversity in the region "Amphibian population declines due to chytridiomycosis can occur very rapidly -- sometimes over a just a few weeks" (Pessier 2010). Notifying the Texas Department of Agriculture is an important first step when a likely infection is spotted. "Chytrid fungus invades the thin, permeable skin of amphibians and appears to kill them by interrupting their ability to regulate the movement of water and oxygen through their skin" (What is, 2010, Save a frog).

The second step is testing. Fortunately, affordable testing for the fungus is available. Tests for amphibian infectious diseases are available from the Wildlife Disease Laboratories of the Institute for Conservation Research at the San Diego Zoo, which offers low-cost screening for chytrid fungus to encourage widespread testing (Pessier 2010). Unfortunately, if chytrid is discovered, it is difficult to contain and treat the infection in a wild population. There have been some experiments using antifungal medication to treat wild amphibians in "to reduce the intensity of infection to a less lethal level with the hope that animals could survive with a mild Bd [Batrachochytrium dendrobatidis] infection…Another promising area of research is looking at the possibility of introducing symbiotic bacteria that inhibit the growth of Bd into wild amphibian populations" (Pessier 2010). Contacting a research university to inquire into the state of current research might be another important step in treatment and containment.

Unfortunately, the exact mode of transmission of the fungus is unclear. Given that it has also been found to exist in pet and zoo populations, ensuring that infected animals are not released to the wild is important. Raising awareness about the presence of the disease amongst amphibian owners is essential, so they do not dispose of unwanted pets and infect wild populations. It is also essential that hikers and casual outdoor observers do not move frogs from one area to another, for fear of spreading the illness. Signs of the sickness in the frogs include discolored, peeling, or rough skin; lethargy, and lack of appetite. However, people should be aware that many frogs initially show no sign of the illness. Additionally, campers and hikers should "clean and dry all equipment and wet or muddy footwear before and between visiting frog sites. This may include cleaning the tires of your vehicle before visiting known high-risk sites where threatened frog species may live" (Frog, 2008, DECC). Zoos should also be made aware of the need to carefully monitor their amphibians, particularly because captive populations can be treated for the disease.