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Australia’s Great Barrier Reef hit by coral bleaching

Article Written By : Jamie Smyth in Sydney

The world’s worst coral bleaching event since 2002 has hit the Great Barrier Reef with unusually high sea temperatures damaging up to 80 per cent of corals at a reef system near Lizard Island, in the north of the world heritage listed structure.

Scientists at the Lizard Island Research Centre said on Tuesday they are witnessing the worst bleaching since 2002 with large tracts of coral losing their colour and turning pale due to heat stress.

They said sea temperatures were one or two degrees hotter than normal for the time of year, which was probably linked to the El Niño weather pattern and climate change.

“In the Lizard Island lagoon about 80 per cent of corals are affected by bleaching to varying degrees,” said Lyle Vail, director of the centre. “It began about three weeks ago and the risk is that it the high temperatures persist for another few weeks the corals could die.”

The Great Barrier Reef is made by billions of tiny invertebrate creatures known as coral polyps, which have built it over the past 600,000 years. The polyps, which excrete calcium carbonate to make reefs, are extraordinarily sensitive to changes in water temperature. When it rises above 31C many species of coral are forced to expel the multicoloured algae that live within its tissues, an effect known as “bleaching”.

The white coral skeletons that remain can regenerate if temperatures fall and water quality conditions are good. But in many instances entire reef systems are destroyed.

Environmental groups WWF and Greenpeace said reports of the bleaching event demonstrate that Australia needs to do more to combat climate change and stop supporting the coal industry.

“This government cannot continue down the path of approving new coal mines,” said Shani Tager, Greenpeace Australia Pacific’s Reef Campaigner.

In October, the National Oceanic Atmospheric Administration in the US declared the world’s third global coral bleaching, following similar events in 1998 and 2010, as bleaching spread across Hawaii and the Caribbean in 2015. With the summer in full bloom in the southern hemisphere, Fiji recently reported coral bleaching, and corals on the Great Barrier Reef are now beginning to experience similar heat stress.

“The Great Barrier Reef experienced mass bleaching in 1998 and 2002, and we have all been keeping an eye on this El Niño to see if there is a risk of another,” said Terry Hughes, director of the ARC Centre of Excellence for Coral Reef Studies.

Unesco is considering whether to put the Great Barrier Reef — the world’s largest living organism — on its ‘danger’ list, while environmentalists are pitched against Australia’s Big Coal. Jamie Smyth reports

“The current reports of bleaching on the reef do not equate to a mass bleaching event, but we are concerned about a growing incidence of minor to moderate bleaching at multiple locations along the reef.”

Australia’s national coral bleaching task force, which was established in October in response to the prediction of a third mass bleaching event, estimates that 5-10 per cent of corals across the reef are affected.

Scientific studies show the reef has come under increasing stress over recent decades, with a 2012 study finding that half of the coral had died over the previous 27 years due to cyclones, bleaching and the coral-eating crown-of-thorns starfish.

Scientists say the next few weeks of peak summer temperatures at the Great Barrier Reef will be crucial to determine if a “mass bleaching” event can be avoided.

Cloud cover or stormy conditions would lead to a reduction in temperatures, allowing corals to recover, they say.

Reference link to this article : http://www.ft.com/intl/cms/s/0/5213b6a2-df7a-11e5-b072-006d8d362ba3.html#axzz41iEzVtHJ


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