Azara Blog: Global warming might be leading to decline in some frog populations

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Date published: 2006/01/12

The BBC says:

The dramatic decline of some frog populations is directly connected to global warming, a new study claims.

The scientists looked at biodiversity hotspots in Central and South America, and found compelling links between frog extinctions and changes in temperature.

They believe the perfect conditions are being created for the spread of a fungus that is deadly to amphibians.

The international team, reporting its findings in Nature magazine, says the impact on biodiversity is "staggering".

Its research focused on the vividly coloured harlequin frogs (Atelopus) which are critically endangered.

Between the 1980s and 1990s, almost two-thirds of the 110 known species became extinct, and a chytrid fungus (Batrachochytrium dendrobatidis) has been suggested as the prime suspect.

The scientists compared the last known sightings of the frogs with recorded sea and air temperatures, and discovered strong correlations.

They propose that climatic changes are leading to outbreaks of disease caused by the chytrid fungus.

The fate of amphibians has previously been connected with the chytrid fungus and climate change, but scientists were puzzled because the fungus is known as a more effective killer at lower temperatures rather than the higher temperatures usually associated with global warming.

But scientists now believe they have unravelled the mystery.

General warming is causing extra cloud cover over the tropical mountains favoured by the harlequin frogs. This means cooler days locally and warmer nights, providing the conditions in which the chytrid fungus thrives.

This was further confirmed by the fact that species of frog that live at very high altitudes where temperatures are very cold, or very low altitudes where they are very hot, have a much better chance of survival than the frogs that live half-way up the mountain.

"We have found evidence that global warming is causing widespread amphibian extinction by triggering outbreaks of disease," said lead author Dr Alan Pounds.

Well, the evidence and line of thinking is thin so far, but it sounds plausible and with further work ought to contribute to better population models.

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