Photo: The Year of the Frog

Because they live in both the aqueous and atmospheric part of the planet, frogs are often the first species affected by environmental problems, and can thus serve as a warning to other species, including ourselves (Credit: Chris Coomber via Flickr).

By David Suzuki with Faisal Moola

During high school in Ontario, I spent a lot of time at a swamp near my family's home. Smelling the sweet air in spring, listening to the frogs croak, and catching the insects that would become so important to my life and career gave me solace during those lonely years.

As much as insects became my fascination, I've always loved the frogs. These amazing amphibians occupy a crucial place in the natural order. They are both predator and prey, providing food for larger species and keeping insect populations in balance by eating them. If frogs were to disappear, the planet would soon be covered in flies and other insects. I like flies, but not that much!

In fact, frogs are disappearing. Many of us can remember drifting off to sleep to the sound of frogs, but unless we act now, it's unlikely that our children and grandchildren will hear the same lullaby. Scientists estimate that one third to one half of the world's 6,000 known amphibian species could go extinct in our lifetime — including many in Canada. This would be the largest mass extinction since the disappearance of dinosaurs. More than 100 species are already believed to have vanished since 1980.

The situation has become so critical that conservationists and institutions including universities, zoos, and aquariums have named 2008 the Year of the Frog. The motto, "Frogs matter. Jump in" is one we should all take to heart. The more we understand about frogs and the reasons for their disappearance, and the more we all get involved in trying to save them, the more likely we will be to head off this impending disaster.

It's not just the frogs we have to worry about. Biologists consider frogs and other amphibians as "the canary in the coal mine". Because they live in both the aqueous and atmospheric part of the planet, frogs are often the first species affected by environmental problems, and can thus serve as a warning to other species, including ourselves.

One of the main threats to frogs and amphibians around the world is the spread of a fungus called chytrid (kit-rid), but other factors that we can start to address immediately are also threatening amphibians. These include global warming, habitat loss, pesticide use, pollution, invasive species, and even overuse as food or pets.

Dealing with the fungus will be a challenge. Chytrid is thought to have been spread initially by trading in the African clawed frog, which was used for pregnancy tests from 1934 to the 1950s. The fungus has now infected more than 100 species of frogs, killing them in a way that is still baffling scientists. The spores infect the outer layer of skin, but scientists have yet to figure out its mechanism. Ironically, the fungus is not fatal to the African clawed frog.

In an attempt to ensure the survival of frog species most threatened by the fungus, biologists from zoos, aquariums (including the Vancouver Aquarium), and botanical gardens, working with the International Union for Conservation of Nature, set up the Amphibian Ark. Under the program, conservationists have started gathering threatened frogs to breed and protect in captivity. There's no guarantee that the scheme will work, but it's worth a try. One of the challenges will be to maintain genetic diversity under such a program. Another big challenge, though, will come when it's time to put the frogs back. Will there even be places left for them to live? And given the crucial role that frogs play in the natural cycle, what will become of those ecosystems while the frogs are away? Global warming is already shifting the areas where species are found, so when it's time to release the frogs, it might not even be realistic to return them to their former homes.

Those are things we can all work to overcome. Some progress has been made. For example, many municipalities and some provinces, such as Quebec, have banned the cosmetic use of harmful pesticides sprayed on lawns and gardens, which threaten frogs and other wildlife. The government of Ontario has announced a similar ban. However, the habitat of frogs and other species are poorly protected when planning and development decisions are made. We can rectify this situation through involvement with conservation groups and by lobbying governments at all levels to implement and enforce laws to protect dwindling frog populations. Our efforts to slow global warming and to cut down on the waste we produce are also steps that will add up to make a real difference. We must listen to the frogs now, so that our children and grandchildren can enjoy the symphony of their songs as we did in our childhood.

April 25, 2008
http://www.davidsuzuki.org/blogs/science-matters/2008/04/the-year-of-the-frog/

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