Amphibian populations are in decline in many areas of the world. In cities and the countryside, in rainforests and wetlands, countless areas which previously hosted a range of healthy amphibian populations now have fewer- or even no- frogs, toads, and salamanders. While healthy populations of some species still exist, many species are in decline and a few species - including Costa Rica's Monteverde golden toad and Australia's Gastric brooding frog - are now believed extinct.
In response to this alarming trend, Amphibian Ark and its member organizations, including the World Association of Zoos and Aquariums (WAZA), have declared 2008 as the “Year of the Frog” to highlight the amphibian extinction crisis and emphasize the importance of amphibian conservation.
Why are Amphibians Declining?
Research to date indicates that a host of environmental variables including competition, contamination, disease, habitat destruction, parasitism, predation, and ultraviolet radiation may cause amphibian population declines or malformations. It is likely that amphibians are subject to combinations of these stressors, and that the combinations vary by region and time.
Why Should We Care?
Amphibians are considered good indicators of general ecosystem health. Many amphibians lay their eggs in water and their offspring spend the first part of their lives in water. Both amphibian eggs and skin are highly permeable, allowing them to absorb water and oxygen. Unfortunately, this makes them especially vulnerable to pollutants which can also readily enter the body.
Amphibians play essential roles, both as predators and prey, in the ecosystems of
the world. Adult amphibians regulate populations of pest insects- those which damage crops or spread disease1. Amphibians have very
important functions in the
food chains of both
aquatic and terrestrial
systems. Amphibians
consume aquatic vegetation, as well as invertebrates and other vertebrates. In the absence of fish,
amphibians are usually the top predators
in freshwater systems. However,
amphibians are also prey to numerous
predators, including snakes, fish, birds,
mammals, spiders, and even each other.
Consequently, amphibians influence the
population dynamics of other organisms,
as well as the cycling of nutrients and the
flow of energy.
Amphibians provide vital biomedicines. These include compounds that are being refined for analgesics and antibiotics2, stimulants for heart attack victims, and treatments for diverse diseases including high blood pressure, potentially life-threatening fungal infections3, stroke, seizures and Alzheimer’s. A man-made version of a molecule discovered in the egg cells of the Northern Leopard frog (Rana pipiens), found in many parts of the United States, could provide the world with the first drug treatment for brain tumours4. The Australian red-eyed treefrog (Litoria chloris) and its relatives give us a compound potentially capable of preventing HIV infection, the cause of AIDS5. In 2000, the World Resources Institute6 reported that of the 150 prescription drugs currently in use in the United States of America, 27 originated from animals.
Research into the mechanics of the unique hearing system of frogs is being used as a model for "intelligent" hearing aids. The hearing aids can spatially separate sounds, process them the way that human brains do, and boost sound signals of interest, ignoring background noise7.
- Amphibian Conservation Summit Declaration. September 17-19, 2005, Washington, D.C.
- Grenard, S. 1994. Medical Herpetology: Amphibians and Reptiles - Their Influence on, and Relationship to, Human Medicine. Reptile and Amphibian Magazine, Pottsville, PA.
- Chivian, Eric II, Bernstein, Aaron. 2008. Sustaining Life: How Human Health Depends on Biodiversity. Oxford University Press, Inc, New York.
- University of Bath. Press Release - 26 June 2007. Frog molecule could provide drug treatment for brain tumours.
- VanCompernolle, S.E., et al. 2005. Antimicrobial peptides from amphibian skin potently inhibit Human Immunodeficiency Virus infection and transfer of virus from dendritic cells to T cells. Journal of Virology 79: 11598-11606.
- WORLD RESOURCES INSTITUTE. 2000. World Resources Report 2000-2001. People and ecosystems: the fraying web of life. Washington D.C.: World Resources Institute, 389 p.
- University of Illinois at Urbana-Champaign. News Release - 21 July 2008. Ultrasonic frogs can tune their ears to different frequencies.
