Amphibians: Facing a current conservation crisis of unprecedented declines and extinctions
Of more than 6,300 known species of amphibians, more than 30% are threatened with extinction according to the Red List standards of IUCN, the International Union for the Conservation of Nature. Amphibians, a class of animals that includes frogs, toads, salamanders, and caecilians, are under threat from multiple factors. But of most urgent concern is the fungal disease, chytridiomycosis, which has caused rapid population declines in many species, and extinctions of several. Because of their sensitivity to environmental change, amphibians are “nature’s indicators.” Their decline serves as a warning that many environments are being degraded.
As both predators and prey, amphibians are vital links in food webs and play critical roles in many ecosystems, including temperate and tropical forests. Indeed, the biomass of amphibians is the greatest of all organisms in ecosystems such as the deciduous forests of the northeastern United States. Their life histories make many integral members of both aquatic and terrestrial environments. Amphibians also control insects, a function vital for worldwide agricultural success, as well as minimizing insect-borne diseases, such as malaria.
In addition to chytridiomycosis, amphibian species are at risk of extinction due to many factors, including habitat loss and degradation, chemical pollutants, unregulated trade, introduced species, and climate change. From one or more of these causes, 165 amphibian species are believed to have gone extinct since 1970; including 39 known to be extinct, or that survive only in captivity, and 130 that have not been found in recent years.
While habitat loss is the greatest threat to amphibians, the chytrid fungus can decimate populations very rapidly, sometimes over the course of only a few weeks. The IUCN has called this “ ... the worst infectious disease ever recorded among vertebrates in terms of the number of species impacted, and its propensity to drive them to extinction.”
In 2005, an Amphibian Conservation Summit, with participants from many countries and institutions, was held in Washington DC. Academic researchers, conservation NGOs, zoos and aquariums, IUCN, and others joined together to create an Amphibian Conservation Action Plan (ACAP). This plan includes captive breeding programs, the only solution available to save some species at this time.
The latter effort, recognized as the Amphibian Ark (AArk), is focused on ensuring the global survival of amphibians, focusing on those that cannot currently be safeguarded in nature. AArk aims to develop captive, survival assurance populations of amphibian species at imminent risk of extinction, with the ultimate goal being return of these species to the wild. The immediate goal is to build the capacity, and facilities, for countries around the world to care for and save their own amphibian species.
The overall effort to implement the ACAP is now being facilitated and coordinated by the Amphibian Survival Alliance, with the assistance of the Amphibian Specialist Group of IUCN’s Species Survival Commission.
One way anyone can help is to purchase only captive-bred amphibians from reliable and ethical sources. Unregulated commercial trade has contributed to the worldwide spread of the chytrid fungus. In addition, never release pet amphibians back into the wild. This applies even to native species collected locally. Releasing pets can introduce parasites and diseases into wild populations, with potentially disastrous results.
To further explore amphibian conservation, see http://amphibiansurvivalalliance.org For more information about chytridiomycosis. and efforts to save amphibian species through captive colonies, see http://www.amphibianark.org For updates on amphibians in general, see: http://amphibiaweb.org Contributed by George B. Rabb, PhD, and Francie Stotz. Dr. Rabb has affiliations with conservation organizations worldwide. Most notably, he is past chairman (1989-1996) of the Species Survival Commission of IUCN, which he helped build into the world’s largest species conservation network. He founded its Declining Amphibian Population Task Force, and subsequently helped establish the Amphibian Survival Alliance. Francie Stotz developed exhibits at The Field Museum for 16 years. Currently she works as an assistant to Dr. Rabb, and writes on a free-lance basis.