Across Planet Earth, Amphibian Species Struggle to Adapt and Survive
Dual Threats of Disease and Habitat Loss Taking Devastating Toll
by Olivia Sanderfoot, age 16
Scientists are still debating both the causes and consequences of global warming, but it is clear that climate change is threatening thousands of species across the globe, especially amphibians.
Across the world, amphibians are disappearing more quickly than any other group of organisms. According to the Global Amphibian Assessment, one-third of the world’s amphibian species is endangered.
Since 1980, almost 125 species of amphibians may have completely disappeared. This decline is caused mainly by two threats: a contagious disease called amphibian chytrid, and habitat destruction. And recent studies have shown that both threats may be linked to global warming.
* * * * *
Amphibian chytrid is a parasitic fungus that causes suffocation. This fungus was originally most likely spread by African clawed frogs, which were shipped around the world for lab studies in the 50s. The disease spreads quickly and currently affects more than 100 species of amphibians.
Some scientists think that because amphibians are cold-blooded, global warming may take a toll on their immune systems, making it difficult for them to fight chytrid disease. Global warming might also be helping the chytrid spread and grow.
“Disease is the bullet killing frogs, but climate change is pulling the trigger,” said J. Alan Pounds, resident scientist at Costa Rica Monteverde Cloud Forest Preserve.
Scientists are still uncertain about many details of the disease. They do not know if amphibians can be protected from chytrid, or how long the disease continues to affect a particular environment area, even after all the amphibians have died. It is almost impossible to stop the fungus in the wild because immunizations would only last one generation. In addition fungicides may harm beneficial fungi.
In addition to chytrid, widespread habitat destruction is hurting amphibian populations. Because amphibians live in both land and water, they are easily affected by changes in either habitat.
Global warming contributes to changes in amphibian habitats, but it also changes animal behavior as species struggle to adapt and survive. Scientists say dozens of amphibian species are moving uphill to cooler climates. But as global temperatures continue to rise, there will be fewer places for them to move.
Amphibians are important prey and predators in many ecosystems. They are also important indicators of water quality. In science, frogs other amphibians are considered sentinel species, or indicator species. These terms mean that what affects amphibians now could affect other species in the future.
“Amphibians may not be as charismatic to most people as mammals,” Kevin Zippel, the program director of the amphibian repopulation program Amphibian Ark, says. “But they are absolutely vital to their ecosystems.”
* * * * *
Conservationists across the globe are working to save amphibians. To help raise awareness and funding for research, the Amphibian Ark named 2008 the “Year of the Frog.”
“The good news, such as it is, is that the new findings will open up avenues of research that could provide conservationists with the means to save the amphibians that still survive,” says Bryce Young, a NatureServe zoologist. “If this cloud has any silver lining, that’s it.”
[Sources: Newsweek, http://news.bbc.co.uk/2/hi/science/nature/6083342.stm, http://news.nationalgeographic.com/news/2006/01/0112_060112_frog_climate.html,]