Endangered frogs
Declining amphibians - a worldwide problem
Internationally amphibians are confronted by a range of threats from habitat destruction to fatal disease. Currently it is thought that 30% (or 1895) of 6285 amphibian species world wide are threatened with extinction while it is believed that 165 species may have already gone extinct (IUCN).
While habitat destruction and degradation has had a significant impact on frog populations in Australia the primary threat to our frogs has come from disease. In the past 30 years there has been a rapid and serious decline in frog numbers, the most dramatic declines have occurred in Queensland.
Queensland's declining frogs
Queensland’s frogs have long been threatened by clearance of native vegetation, drainage of wetlands, changes to flow regimes and pollution. With increasing urbanisation and a growing population in Queensland, the pressure on frog habitat is increasing.
Disease has emerged as a major threat to Queensland frogs. In the late 1970’s and early 1980’s dramatic declines were observed in the largely pristine habitat of the rainforest streams of the Great Dividing Range. First in south east Queensland and then on the Eungella Plateau, and in the early 1990’s the declines were evident in the Wet Tropics of north east Queensland. These declines were rapid and catastrophic to the point that today it is almost certain that five species have gone extinct, with a further one possibly extinct and six other species have declined dramatically.
The cause of these declines was initially unexplained until research in the late 1990’s indicated that the cause was a deadly fungus. Batrachochytrium dendrobatidis or Amphibian chytrid as it is more widely known is a waterborne fungus that produces zoospores which infect frogs and cause a lethal infection. Recent research has shown that the disease has more of an impact on frogs at low temperatures, explaining why frog populations at higher altitudes (therefore lower temperature) appear to be more susceptible to the fungus.
As frogs are sensitive to environmental conditions, they may be likened to 'the canary in the coalmine', providing the first indications of a detrimental change in global environmental conditions. The impact of climate change is likely to reduce resilience in already struggling frog populations pushing them closer to extinction.
Related information
Alford, R.A. and Richards, S.J. 1999. Global Amphibian Declines: A problem in applied ecology. Annual Review of Ecology and Systematics 30: 133-165
Berger, L, Speare, R., Daszak, P., Green, E.D., Cunningham, A.A., Goggin, C.L., Slocombe, R., Ragan, M.A., Hyatt, A.D., McDonald, K.R., Hines, H.B., Lips, K.R., Marantelli, G., and Parkes, H. 1998. Chytridiomycosis causes amphibian mortality associated with population declines in the rainforests of Australia and Central America. Proceedings of National Academy of Science 95: 9031-9036.
Campbell, A. (Ed). 1999. Declines and Disappearances of Australian Frogs. Environment Australia: Department of Environment and Heritage, Canberra. Pp 234.
Gascon, C., Collins, J.P., Moore,R.D., Church, D.R.McKay, J. E. and Mendelson III, J.R. (eds) 2007. Amphibian Conservation Action Plan. IUCN/SSC Amphibian Specialist group. Gland, Switzerland and Cambridge, UK. 64pp.
Hazell, D. 2003. Frog ecology in modified Australian landscapes: a review. Wildlife Research 30: 193-205.
Hazell, D., Hero, J-M., Lindenmayer, D. and Cunningham R. 2004. A comparison of constructed and natural habitat for frog conservation in an Australian agricultural lanscape. Biological Conservation 1: 61-71.
Hero, J-M., Morrison, C., Gillespie, G., Roberts, D., Newell, D.,Meyer, E. McDonald, K., Lemckert F.,Mahony, M., Osborne, W., Hines, H., Richards, S., Hoskin, C., Clarke, J., Doak, N. and Shoo, L. 2006. Overview of the conservation status of Australian frogs. Pacific Conservation Biology. 12: 313-320.
Jansen, A. and Healey, M. 2003. Frog communities and wetland condition: relationships with grazing by domestic livestock along an Australian floodplain river. Biological Cosnervation 2: 207-219.
Skerratt, L. F., Berger, L., Speare, R., Cashins, S., McDonald, K.R., Phillott, A.D., Hines, H.B. and Kenyon N. 2007. Spread of Chytridiomycosis has caused the rapid global decline and extinction of frogs. EcoHealth 4: 125-134.
IUCN (International Union for Conservation of Nature and Natural Resources) Key findings of the assessment of the conservation status of the world’s 6,000+ known species of frogs, toads, salamanders, and caecilians.as well as individual species accounts including IUCN Red List threat category, range map, ecology information, and other data for every amphibian species.
James Cook University (JCU) web page on Amphibian disease
Recovery Plans Threatened Species and Communities, Department of Sustainability, Environment, Water, Population and Communities.
Action plans for Australian Frogs Threatened Species and Communities, Department of Sustainability, Environment, Water, Population and Communities.
Amphibian Specialist Group webpage
For a monthly update of papers on amphibian declines and conservation go to AmphibiaWeb.
Last updated 4 February 2011