Great Barrier Reef decline blamed on global warming

CORALS on the Great Barrier Reef are growing slower than at any time in at least 400 years and leading scientists are blaming climate change.

As a major study is being published in the US, scientists fear the reef is showing signs of mass coral bleaching, last seen in 2002.

Glenn De’ath, co-author of the research published in Science magazine, said the corals would stop growing altogether by 2050 if the trend identified in the study continued.

“When you disturb an ecosystem in this way, you get a cascading effect. You then get a chain reaction — the fish habitat is lost,” Dr De’ath said.

Researchers examined more than 300 coral samples, some more than 400 years old, taken from Reef sites.

While the study looked only at Great Barrier Reef samples, the findings have implications for reefs around the world.

The study concluded corals grew steadily until 1990, when samples revealed a “severe and sudden decline” in growth.

Dr De’ath, of the Australian Institute of Marine Science in Townsville, said corals were likely reacting to the increased acidity of the ocean due to higher levels of carbon dioxide in the atmosphere. This acidification made it harder for corals to form skeletons, he said.

Warnings of a high risk of coral bleaching on the northern parts of the Reef from December to February were issued by the National Oceanic and Atmospheric Administration in the US and the Great Barrier Reef Marine Park Authority.

Bleaching occurs when coral discards the coloured algae which it relies on for nutrients.

University of Queensland coral scientist Ove Hoegh-Guldberg said weather conditions mirrored those seen before the 1998 and 2002 mass bleaching events.

“These previous events involved over 50 per cent of the reef bleaching and about 5 to 10 per cent of affected corals dying. It’s difficult not to come to the conclusion we are headed for a similar scale incident,” he said.

“We are starting to see the beginnings of coral bleaching on the reef flats surrounding Heron Island (on the southern end of the reef). I don’t think it looks very good at all.”

Of the Science research, he said: “We may have seriously underestimated the rate of climate change and this should compel us to drastic steps to decarbonise Australian and global economic systems.”

AIMS chief executive Ian Poiner said a research vessel which returned from northern reef sites on December 23 had found only a small number of reefs showing signs of bleaching.

But he said scientists were on stand-by to visit any bleached areas to gather information on the types of corals most affected.

Graham Readfearn, Courrier Mail, 2 January 2009. Article.

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