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'Global warming killing frogs'
12/01/2006 11:27 - (SA)
Paris - Global warming has wiped out two-thirds of species of unique frogs that inhabit the cloud forests of Central America, a study published on Thursday in Nature, the British weekly science journal, says.
Sixty-seven percent of the 110 varieties of harlequin frog, along with the golden toad, have disappeared from tropical America in the past 20 years, the paper says.
The authors point the finger at a fungus called Batrachochytrium dendrobatidis that grows on the frog's skin and eventually slays the amphibian.
Outbreaks of the fungus are clearly linked to man-made global warming, say the authors, led by Alan Pounds of the Monteverde Cloud Forest Preserve in Costa Rica.
Global warming has increased cloud formation in the Latin American tropics, which in turn lowers daytime temperatures but raises nighttime ones, thus creating fantastic growth conditions for the fungus.
Previous research has already highlighted the perils facing the world's amphibians.
Of the world's 1 856 known amphibian species, 427 are listed as critically endangered, including 122 species that are possibly extinct.
Pondering the reason for the die-out
One big question was why this die-out has been occurring, for many of the species lived in habitats that were almost untouched by man.
Suspicion pointed to climate change, but there was no scientific evidence to prove the link.
"With climate change promoting infectious disease and eroding biodiversity, the urgency of reducing greenhouse-gas concentrations is now undeniable," the study says firmly.
"As temperatures rise, climate fluctuations may cross thresholds for certain pathogens, triggering outbreaks. Many diseases are expected to become more lethal, or to spread more readily, as earth warms."
Meanwhile, a study published this week in the British journal Biology Letters warns of the knock-on impact of climate shifts on whale populations.
British scientists looked at population numbers among southern right whales.
Their estimates, dating back 30 years, looked at individually identifiable whales spotted at their breeding grounds off the coast of Argentina in the Southwest Atlantic.
Breeding success was strongly linked with occurrences of El Nino, the disruptive build-up of warm water in the Western Pacific, which in turn had an impact on krill, the whales' staple food, in the Southern Ocean.
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