Australian Scientists: Coral Decline Warns of Ocean Changes

Published on Friday, January 2, 2009 by Agence France Presse

Coral Decline Warns of Ocean Changes: Australian Scientists

SYDNEY - A sharp slowdown in coral growth on Australia's Great Barrier
Reef since 1990 is a warning sign that precipitous changes in the world's
oceans may be imminent, scientists said Friday.

Strong evidence points to the cause being a combination of warmer seas and
higher acidity from increased levels of atmospheric carbon dioxide,
Australian Institute of Marine Science researchers reported.

"The data suggest that this severe and sudden decline in calcification is
unprecedented in at least 400 years," said Glenn De'ath, principal author
of a paper published Friday in the international journal Science.


The research shows that corals on the reef have slowed their growth by
more than 14 percent since the "tipping point" year of 1990 and on current
trends the corals would stop growing altogether by 2050.

"It is cause for extreme concern that such changes are already evident,
with the relatively modest climate changes observed to date, in the
world's best protected and managed coral reef ecosystem," said co-author
Janice Lough.

Coral skeletons form the backbone of reef ecosystems and provide the
habitat for tens of thousands of plant and animal species and more acidic
oceans will affect many sea creatures, not just coral, a statement on the
report said.

"All calcifying organisms that are central to the function of marine
ecosystems and food webs will be affected, and precipitous changes in the
biodiversity and productivity of the world's oceans may be imminent," it
added.

The findings are based on analyses of annual growth bands -- like rings on
trees -- extending back in time up to 400 years.

Rising sea temperatures are blamed on global warming caused by the
build-up in the atmosphere of greenhouse gases such as carbon dioxide --
which is also blamed for higher acidity in sea water.

A UN report warned in 2007 that the Great Barrier Reef, described as the
world's largest living organism, could be killed by climate change within
decades.

The World Heritage site and major tourist attraction, stretching over more
than 345,000 square kilometres (133,000 sq miles) off Australia's east
coast, could become "functionally extinct", the report said.

The journal Science is published by the American Association for the
Advancement of Science.

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