Bleaching kills third of coral in Great Barrier Reef's north

May 30, 2016 by Kristen Gelineau
This February, 2016 photo released Monday, May 30, 2016 by ARC Centre of Excellence for Coral Reef Studies shows mature stag-horn coral bleached at Lizard Island, Great Barrier Reef off the eastern coast of northern Australia. The reef studies center released the results of its survey of the 2,300-kilometer (1,430-mile) reef off Australia's east coast on Monday. The scientists found that about 35 percent of the coral in the northern and central sections of the reef are dead or dying. Some parts of the reef had lost more than half of the coral to bleaching. (David Bellwood/ARC Centre of Excellence for Coral Reef Studies via AP)

Mass bleaching has killed more than a third of the coral in the northern and central parts of Australia's Great Barrier Reef, though corals to the south have escaped with little damage, scientists said on Monday.

Researchers who conducted months of aerial and underwater surveys of the 2,300-kilometer (1,400-mile) reef off Australia's east coast found that around 35 percent of the coral in the northern and central sections of the reef are dead or dying, said Terry Hughes, director of the ARC Centre of Excellence for Coral Reef Studies at James Cook University in Queensland state. And some parts of the reef had lost more than half of the coral to bleaching.

The extent of the damage, which has occurred in just the past couple of months, has serious implications, Hughes said. Though bleached corals that haven't died can recover if the water temperature drops, older corals take longer to bounce back and likely won't have a chance to recover before the next bleaching event occurs, he said. Coral that has died is gone for good, which affects other creatures that rely on it for food and shelter.

"Is it surprising? Not anymore. Is it significant? Absolutely," said Mark Eakin, the coral reef watch coordinator for the U.S. National Oceanic and Atmospheric Administration. "We're talking about losing 35 percent of the population of coral in some of these reefs—that's huge."

The damage is part of a massive bleaching event that has been impacting reefs around the world for the past two years. Experts say the bleaching has been triggered by global warming and El Nino, a warming of parts of the Pacific Ocean that changes weather worldwide. Hot water puts stress on coral, causing it to turn white and become vulnerable to disease. Other reefs have suffered even more severely from the recent bleaching; Some Pacific islands, for example, have reported coral death rates of more than 80 percent, Eakin said.

This is the third and most extreme mass bleaching event in 18 years to strike the Great Barrier Reef. In each case, the areas that suffered the worst bleaching were the areas where the water was hottest for the longest period of time, Hughes said.

This April, 2016 photo released Monday, May 30, 2016 by ARC Centre of Excellence for Coral Reef Studies, shows mature stag-horn coral dead and overgrown by algae at Lizard Island, Great Barrier Reef off the eastern coast of northern Australia. The reef studies center released the results of its survey of the 2,300-kilometer (1,430-mile) reef off Australia's east coast on Monday. The scientists found that about 35 percent of the coral in the northern and central sections of the reef are dead or dying. Some parts of the reef had lost more than half of the coral to bleaching. (David Bellwood/ARC Centre of Excellence for Coral Reef Studies via AP)

This time, the southern half of the reef was spared largely due to a lucky break that arrived in the form of a tropical cyclone. The remnants of the storm which had lashed the South Pacific brought cloud cover and heavy rains to the region, cooling the ocean enough to stop bleaching that had just begun in the south. About 95 percent of the coral in the southern portion of the reef has survived.

Storms have previously proven very helpful for heat-stressed reefs, Eakin said. In 2005, for instance, the quick succession of Hurricane Katrina and Hurricane Rita cooled the waters below as they passed over Florida, sparing the Florida Keys from a serious coral bleaching event affecting the Caribbean.

Experimental approaches to the bleaching dilemma have included attempts to lower water temperatures by using shades to cover corals, Eakin said. But such efforts require massive amounts of preparation and can only be done in small areas, Eakin said. Other solutions may lie in finding ways to minimize additional stressors to the already fragile reef.

"Anything you can do to reduce the level of injury and stress coming from other sources, the better the chance that the corals are going to survive," Eakin said. "Those reefs that have recovered after events like this are the ones that are the most protected, least visited and least disturbed."

Last year, the United Nations' heritage body expressed concern about the state of the Great Barrier Reef and urged Australia to boost its conservation efforts.

Following the release of the bleaching report on Monday, Australian politicians—who are in the midst of an election campaign—jumped on the issue, with the opposition Labor Party pledging to create a $500 million fund for better management and research of the reef. Environment Minister Greg Hunt, meanwhile, announced that if his party is re-elected, the government would invest $6 million to helping combat the crown-of-thorns starfish, which feast on coral.

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8 comments

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MrData
3.2 / 5 (5) May 30, 2016
"...included attempts to lower water temperatures by using shades to cover corals..." Makes about as much sense as turning on the air conditioner whilst you have the heater on full throttle. Solve the CO2 problem and job done.
antialias_physorg
4.5 / 5 (8) May 30, 2016
Solve the CO2 problem and job done.

You are aware that if we solve the CO2 porblem now then the timeframe until the excess CO2 we have in the air right now disappears is on the order of a century or more?

The problem they have observed in the article are over a period of months/few years. Solving the CO2 poblem now (though advisable) isn't going to be enough to save these critters.
leetennant
4.2 / 5 (5) May 30, 2016
Unfortunately, we knew this was coming well over 10 years ago and did nothing about it. The last election was a turning point in this country and people fucked it up. And now we're going to live with the consequences. The reef is permanently scarred. It will never recover. Even if we somehow miraculously grow up in the next year and shift sharply to a low-emission global economy, the reef is dead.

We did this and we should be ashamed.
antigoracle
1 / 5 (5) May 30, 2016
Can you Chicken Littles say "El Nino"
leetennant
3 / 5 (4) May 30, 2016
Yes, large-scale irreparable bleaching happens every El Nino. That's why the reef died in 1998.
Colbourne
5 / 5 (1) May 31, 2016
Is it possible to replace the coral with species more tolerant of the higher temperatures ?
I am assuming this will eventually happen naturally ,but probably could be aided by humans to speed up the process.
BackBurner
1.5 / 5 (8) Jun 05, 2016
The reef is permanently scarred. It will never recover.


50 years ago (give or take) a 15 megaton thermonuclear bomb was detonated 10 feet above the Bikini atoll in the South Pacific.

Today the reef is doing fine.

Where is it you get ideas like this?
BackBurner
1.5 / 5 (8) Jun 05, 2016
Is it possible to replace the coral with species more tolerant of the higher temperatures ?


What gives you the idea it has anything to do with water temperature? Temperatures change constantly as currents change. The temperature gradient from 0 to 90 feet is larger than any oceanic warming that's occurred over the past 100 years, and coral grows very well through that entire range.

Coral is a symbiot. The living portion dies off in a cycle and regrows. It happens constantly.

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