Advertising

The Seattle Times Company

NWjobs | NWautos | NWhomes | NWsource | Free Classifieds | seattletimes.com

Nation & World


Our network sites seattletimes.com | Advanced

Originally published Thursday, May 8, 2008 at 12:00 AM

Print

Carbon dioxide bad for koalas?

Koalas are threatened by the rising level of carbon-dioxide pollution in the atmosphere because it saps nutrients from the eucalyptus leaves...

The Associated Press

CANBERRA, Australia — Koalas are threatened by the rising level of carbon-dioxide pollution in the atmosphere because it saps nutrients from the eucalyptus leaves they feed on, a researcher said Wednesday.

Ian Hume, emeritus professor of biology at Sydney University, said he and his researchers also found that the amount of toxicity in the leaves of eucalyptus saplings rose when the level of carbon dioxide within a greenhouse was increased.

Hume presented his research on the effects of carbon dioxide on eucalyptus leaves to the Australian Academy of Science in Canberra on Wednesday.

The researchers found that carbon dioxide in eucalyptus leaves affects the balance of nutrients and "anti-nutrients" — substances that are either toxic or interfere with the digestion of nutrients.

An increase in carbon dioxide favors the trees' production of carbon-based anti-nutrients over nutrients, so leaves can become toxic to koalas, Hume said.

Some eucalyptus species may have high protein content, but anti-nutrients such as tannins bind the protein so it cannot be digested by koalas.

Hume estimated that current levels of global carbon-dioxide emissions would result in a noticeable reduction in Australia's koala population in 50 years due to a lack of palatable leaves.

Out of more than 600 eucalyptus species in Australia, koalas will only eat the leaves of about 25, Hume said. Changing the toxicity levels in the trees could further reduce the varieties that koalas find palatable, he said.

"Koalas produce one young each year under optimal conditions, but if you drop the nutritional value of the leaves, it might become one young every three or four years," Hume said.

Hugh Tyndale-Biscoe, a marsupial physiologist, said that eucalyptus leaves already have little nutritional value and that koalas have adapted to their poor diet by sleeping to conserve energy.

"It's a very precarious existence," Tyndale-Biscoe said. "They basically sleep for 20 hours a day and then they've got four hours to do everything else — occasionally eat a leaf and maybe once a year go after another koala" to mate.

Copyright © 2008 The Seattle Times Company

More Nation & World headlines...

Print      Share:    Digg     Newsvine

advertising

UPDATE - 10:01 AM
Rebels tighten hold on Libya oil port

UPDATE - 09:29 AM
Reality leads US to temper its tough talk on Libya

UPDATE - 09:38 AM
2 Ark. injection wells may be closed amid quakes

Armed guards save Dutch couple from Somali pirates

Navy to release lewd video investigation findings

Advertising

Video

Marketplace

 
Most read
Most commented
Most e-mailed
 
 

Most viewed imagesMore

Advertising