Silent forest

By Evelyne Daigle | 27 July 2012| Panama
1129 - I - Photo credit Frogs breath and drink through their permeable skin which makes them vulnerable to pollution and chytrid Frogs breath and drink through their permeable skin which makes them vulnerable to pollution and chytrid
1127 - I - Photo credit Edgardo Griffith, herpetologist, director of the EL VALLE AMPHIBIAN CONSERVATION CENTER Edgardo Griffith, herpetologist, director of the EL VALLE AMPHIBIAN CONSERVATION CENTER
1128 - I - Photo credit Edgardo, sad not to be able to hear the frogs sing into the rainforest Edgardo, sad not to be able to hear the frogs sing into the rainforest
1126 - I - Photo credit Scientists test the presence of the chytrid fungus on the frog's skin Scientists test the presence of the chytrid fungus on the frog's skin
1130 - I - Photo credit There are over 600 frog species in the world There are over 600 frog species in the world

In 2003, Edgardo Griffith, a respected herpetologist and director of the El Valle Amphibian Conservation Center in Panama, loved to sit by a stream in the rainforest and listen to the chorus of frog calls. It brought him great happiness.

But since 2006, the rainforest has been silent, and Griffith is deeply sad about it, even more so because his son may never hear the musical song of these frogs that have disappeared. So what happened?

We can trace the origin of this silence back to the 1930s and 40s in South Africa, where a certain species of frog (Xenopus laevis) was used in a pregnancy test. Hormones in the urine of pregnant women provoked egg-laying in this species. Useful and valuable, the frog was thus exported around the world to detect human pregnancy. What we didn’t know, however, was that it was a carrier of the chytrid fungus, while being immune to the disease itself. Hence, the fungus spread insidiously through labs around the world. Over the years, medicine evolved and the frog became unnecessary for pregnancy tests, and it was often released into the environment. This resulted in the chytrid fungus being transmitted to other more vulnerable species of frog all over the world.

The chytrid fungus can spread through waterways or even through moisture in the air. Since frogs are amphibians that “drink and breathe” in part through their permeable skin, the fungus enters their skin and acts as a sealant. The skin thickens and the frogs are smothered, suffocate, become dehydrated, and suffer electrolyte imbalances. This eventually causes their hearts to stop.

Today, the chytrid fungus has spread to every continent except Antarctica.

What would happen if frogs disappeared from earth? What is their importance to an ecosystem? Because they live both on land and in water, they are affected by both land and water pollution. This makes frogs a barometer of an ecosystem’s health, the proverbial canary in the coal mine. As insect eaters, they control populations of insects that bear diseases such as malaria and that damage crops. They are also a source of food for other animals. Clearly, they play a vital ecological role.

So the equation is simple: if frogs disappear, it’s a sign that the environment is not doing well.

But as experts seek solutions to the invisible scourge of the chytrid fungus, Edgardo Griffith and his team are working tirelessly to push the enemy back. They are trying to buy time, protecting frogs in their conservation centres, hoping that they may once more hear the melodious calls of these threatened animals.

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