We are currently experiencing one of the greatest extinctions ever faced by humankind. 

Of the world’s known 5,743 species of amphibians, 43% are in decline; 32% threatened; 2% are thought to be extinct (just since 1980) and the remaining 23% are data deficient, so we don’t know their present status. In contrast, fewer than one percent of species show population increases. This extinction rate is the worst for any species being faced globally – worse than birds listed as 12% and mammals at 23%.

This is a potentially catastrophic situation for the world’s amphibians. 

And in our region, what is happening with this extinction crisis? Are we affected? 

Australia has one of the most diverse frog assemblages in the world with 219 species of which 93% are endemic to Australia. Dramatic declines in frog numbers have been reported since the 1980s (IUCN 2005). At least 27% of the 219 Australian frog species are threatened with extinction. Seven species are believed to have become extinct in the last 30 years. At least 33 species are now considered Endangered or Critically Endangered.

All four New Zealand species are considered threatened, with two species listed as ‘nationally critical’ under the New Zealand Department of Conservation’s threat classification system. Only two of the four New Zealand species are still found on the mainland, one of which has recently suffered a dramatic decline in population.

In Papua New Guinea (PNG) two species are recognised as Vulnerable and ten are Data Deficient; however, as PNG has numerous undescribed species, these figures are conservative (Menzies, 2006).

The Situation in Western Australia

Seventy-eight frog species are known in Western Australia. While it is thought that WA has not experienced the declines seen in other parts of Australia, only three species have been surveyed to determine their status since 1992 (Roberts et al 1999).

The three species, the White-bellied frog (Geocrinia alba), Orange-bellied frog (Geocrinia vitellina) and the Sunset frog (Spicospina flammocaerula) are all classified as “threatened” under the Western Australian Wildlife Conservation Act 1950.

In 1998 the Western Australian Threatened Species Committee listed G.vitellina and S. flammocaerula as vulnerable and G. alba as endangered (Roberts et all 1999). In 1995 a Recovery Plan was drawn up for the Geocrinia species (Wardell-Johnson et al 1998) in which a recommended action was captive breeding. The recovery plan for the Sunset Frog, S. flammocaerula, (Burbidge A, Roberts, J 2002) notes that nothing is known of the food preferences, predation risk or habitat use of this species. There is a clear need for further research on these species.

The need to focus on disciplined attempts to establish protocols for captive frog husbandry and breeding is highlighted by a survey indicating that, despite 70% of Australian frog species having been held in captivity, less than 20% have been bred and these mostly represented species with few if any unusual lifestyle characteristics (Marantelli, 1999). It is apparent that only a small number of species of frogs have been studied extensively in captivity.

What is happening and why are amphibians facing this situation?

There are, of course, common themes in the amphibian extinction crisis. Habitat loss through land-use change and commercial over-exploitation are some of the most significant continuing impacts on amphibian populations. Pollution of habitats remains a serious threat but, increasingly, the rise of the infectious disease chytridiomycosis, commonly named Chytrid fungus is causing serious concern.  Predictions recently cited in Science Magazine identified that:

...within 4 to 6 months of BD (chytrid) arrival at a site where it has not previously been present, ~50% of amphibian species and ~ 80% of individuals may disappear.  Global climate change may be encouraging local conditions ideal for BD’s (chytrid) persistence or spread…(Science, July 2006)

One frightening aspect of Chytrid fungus is that it is unstoppable and untreatable in wild and pristine environments where it survives well and spreads swiftly. However, and importantly, it can be successfully managed and eliminated in captive colonies of amphibians.

Chytrid is affecting amphibians globally, to the point that chytrid has been described as:

The worst infectious disease ever recorded among vertebrates in terms of the number of species impacted, and its propensity to drive them to extinction. (IUCN 2004-5)

As a result of this impending disaster, the World Conservation Union (or IUCN) has for the first time turned to zoos and aquariums to assist in addressing this extinction crisis. The IUCN declared in 2005:

Survival assurance populations are mandatory for amphibian species that will not persist in the wild long enough to recover naturally once environments are restored; these species need to be saved now through ex-situ measures …(2005 IUCN ACAP White Papers);

and in 2006:

The only hope for populations and species at immediate risk of extinction is immediate rescue for the establishment and management of captive survival assurance colonies (2006 IUCN ACAP).

One of the recent developments as a result of this call has been the establishment of AArk, the Amphibian Ark.  This was formed by the World Association of Zoos and Aquariums (WAZA) and the Conservation Breeding Specialist Group (CBSG) working together to coordinate the global amphibian ex-situ conservation response. AArk is endorsed and supported by the IUCN Species Survival Commission.

What is AArk?