TFIP003: Occurrence and impact of an introduced fungal disease pathogenic to amphibians at the Sydney Olympic precinct
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Sydney Olympic Park Authority (SOPA)
We hope this project will form the basis for an external funding application.
It is now well accepted that amphibians worldwide are in the midst of an extinction crisis. A recent international review reported that 32% of the world’s amphibians are critically endangered, a level twice that of any other vertebrate group.
The major cause of the decline is hypothesized to be a pathogenic fungus. Genetic studies indicate that the fungus is native to southern Africa and has been dispersed to other regions of the world presumably by animal movement. The native amphibians of Australia consist of a large endemic component that has independently evolved on the Australian continent for over 80 million years. When exposed to a pathogen from another continent they are naïve and susceptible. Since the arrival of the pathogen, postulated to have been in the late 1970’s ten native species have become extinct, and 30 others are now listed as endangered. This is the highest rate of extinction of any vertebrate group since European settlement of Australia.
Evolutionary theory predicts that a disease should not cause the extinction of their host, since as the density of the host reduces the growth and dissemination of the pathogen becomes limited. Why then have some species already progressed to extinction? We hypothesize that in mixed species communities some species act as reservoirs for the disease that is then transmitted to susceptible species, and the level of pathogen present remains high in the environment. In other situations it appears that in certain habitats species are afforded protection. An example is the endangered green and golden bell frog.
The Sydney Olympic Park precinct supports one of the largest populations of the nationally endangered green and golden bell frog. The long-term persistence of the frog at the site is an objective of the Management Authority. To understand the impact of the disease and its relationship to habitats requires research and investigation of the occurrence (presence/absence) of the disease.
We have established the molecular genetic pathology test for the pathogen in our laboratory, and this is the only laboratory in NSW with expertise to conduct this test. Until the development of this procedure the only means to determine if the pathogen was overt symptom in diseased animals at late stage progression. No rapid test for sub-clinical carries was possible. The test is based on DNA technology, is species specific and can operate with small samples from animals and the environment.
Sydney Olympic Park Authority: Question; Is the population of the endangered green and golden bell frog at Homebush Bay infected with the pathogen and if so at what prevalence?