What is chytrid fungus?
A healthy Tasmanian tree frog
copyright: Iain Stych
Chytrid (pronounced kit-rid) fungus (Batrachochytrium dendrobatidis
) causes the disease known as chytridiomycosis or chytrid infection which is a threat to Tasmania's native amphibians. The fungus infects the skin of frogs destroying its structure and function, and can ultimately cause death.
Chytrid infection has been devastating to frog species worldwide and has been implicated in the decline of over 500 species and the presumed extinction of up to 90 species over the last 50 years. The first chytrid record in Australia was in 1978. The international trade of frogs probably brought the fungus to Australia from Africa. Chytrid has been identifed as the cause of extinction of four frog species in Australia and has been implicated in the decline of 43 other species — representing a fifth Australia's amphibian diversity.
What is the threat to Tasmanian frogs?
Tasmania supports 11 frog species
with three of these species, the Tasmanian Tree Frog, the Tasmanian Froglet and the Moss Froglet, found nowhere else in the world. In addition, two other frog species, the Green and Golden Frog and the Striped Marsh Frog, are listed as threatened in Tasmania. Chytrid infection has the potential to impact these species, and other frog populations. Despite the presence of chytrid in Tasmania for at least 20 years there has been no major decline in the distribution of our frogs species, although deaths to individal frogs due to chytrid have been reported. Chytrid appears to be absent from large parts of the Tasmanian Wilderness World Heritage Area and this may have protected populations of our endemic species.
What does an infected frog look like?
Great Barred Frog from Queensland with chytrid infection
copyright: Lee Berger
- Abnormal posture and behaviour. Frogs may sit with their hind legs out, wobble or show difficulty moving or fleeing, or may even have a seizure.
- Skin changes. The skin may be discoloured, peel, or possibly ulcerated. The body may swell.
- Sudden death.
- Tadpoles may demonstrate abnormal mouthparts. These abnormalities are difficult to detect and require expertise.
How is it spread?
The movement of infected frogs, tadpoles and water are the known key agents of spread. The fungus (or infected frogs or tadpoles) can be spread by people in water and mud on boots, camping equipment and vehicle tyres, and in water used for drinking, or spraying on gravel roads or fighting fires.
Where is chytrid in Tasmania?
In Tasmania, chytrid occurs widely in habitats associated with human disturbance. Once established, it is extremely difficult to eradicate chytrid fungus from the natural environment. Remote areas in Tasmania, particularly the Tasmanian Wilderness World Heritage Area, are still largely free of disease and it is our challenge to keep it out.
Dristribution of chytrid records from the Natural Values Atlas
What is being done?
Information on how how to minise the spread of chytrid (and other pathogens) has been made available and biosecuity actions have been embedded into the management systems of land management agenices. Bootwash stations have been established at key entry points to remote locations in Tasmania to help prevent the spread of the disease.
Research has been conducted into the the distribution of the disease and its impacts on some frog species by DPIPWE and other organisations. Frog populations are also monitored.
The National Chytrid Threat Abatement Plan
aims to prevent further spread of chytrid fungus in Australia, and to decrease the impact of the fungus on currently infected populations.
DPIPWE supports the national threat abatement plan through the strategy
for managing wildlife disease in the Tasmanian Wilderness World Heritage Area. Chytrid fungal disease is the top priority in the Strategy and a number of management actions are being undertaken. In addition, the Wildlife Health in Tasmania Manual
describes chytrid infection in more detail.
Is there any effective treatment?
To date there is no effective way to effectively treat wild infected frog populations. The main aim of management is to prevent further spread of chytrid fungus from infected to uninfected sites.
Chytrid fungus is killed by effective cleaning and drying. In addition, a number of disinfectants are effective.
What to consider when collecting and reporting tadpoles and frogs
- If it is necessary to collect tadpoles or frogs, always return them to the collection site. Contact DPIPWE for information relating to frog collection and permits. Never move frogs or tadpoles to new locations.
- Remember it is an offence to take or disturb frogs and tadpoles in Tasmania's national parks and other reserves without a permit. It is also an offence to bring frogs or tadpoles into reserves.
- Never release frogs found in imported fresh produce (usually banana boxes) and nursery products. Report non-Tasmanian frogs for collection to Natural Values Conservation (03 6165 4305) or via email@example.com
- Report sightings of sick or dead frogs to Natural Values Conservation (03 6165 4305) or via firstname.lastname@example.org
What you can do to stop the spread of chytrid
- Keep your gear clean - clean boots and camping equipment of soil and allow to dry completely before visiting remote areas.
- Plan to wash and dry vehicles (including tyres) and equipment before entering dirt roads within areas that are reserved or largely free of human disturbance.
- Think about water disposal - when disposing of small or large volumes of water within a natural environment, ensure you are as far as possible from creeks, rivers, ponds and lakes. A dry stony disposal site is far preferable to a moist muddy one.
- Avoid transferring aquatic plants, water, soils and animals between frog habitats (for example, nursery plants, wet land fill and fish).
- Education in relation to disease management is critical if we are to stop the spread of this important disease. Spread the word!