Part of Great Barrier Reef now ‘a white desert’

[alicia-w]

New bleaching follows major event last year in Caribbean

By Michael Perry
Reuters
Updated: 10:56 a.m. ET March 14, 2006

This report is part of a Reuters series exploring what some experts call an “extinction crisis.” The series was written ahead of a March 20-31 meeting in Brazil of environment ministers from around the world to respond to threats to Earth’s biodiversity.


SYDNEY - When marine scientist Ray Berkelmans went diving at Australia’s Great Barrier Reef earlier this year, what he discovered shocked him -- a graveyard of coral stretching as far as he could see.

“It’s a white desert out there,” Berkelmans said after returning from a dive to survey bleaching -- signs of a mass death of corals caused by a sudden rise in ocean temperatures -- around the Keppel Islands.

Australia has just experienced its warmest year on record and abnormally high sea temperatures during summer have caused massive coral bleaching in the Keppels. Sea temperatures touched 84 degrees Fahrenheit, the upper limit for coral.

High temperatures are also a condition for the formation of hurricanes, such as Katrina which hit New Orleans in 2005.

“My estimate is in the vicinity of 95 to 98 percent of the coral is bleached in the Keppels,” said Berkelmans from the Australian Institute of Marine Science.

Caribbean bleaching last year
Marine scientists say another global bleaching episode cannot be ruled out, citing major bleaching in the Caribbean in the 2005 northern hemisphere summer, which coincided with one of the 20 warmest years on record in the United States.

“In 2002, it would appear the Great Barrier Reef went first and then the global bleaching followed six to 12 months later. Is it the same this time around? No,” said Berkelmans.

“The Caribbean beat us to it. We seem to be riding on the back of that event. We don’t know what is ahead in six months for the Indian Ocean reefs as they head into their summer.”

“This might be part of a global pattern where the warm waters continue to get warmer.”

Other threats to coral reefs -- vast ecosystems often called the nurseries of the seas -- include pollution, over-fishing, coastal development and diseases.

Corals are vital as spawning grounds for many species of fish, help prevent coastal erosion and also draw tourists.


Algae expelled
Bleaching is due to higher than average water temperatures, triggered mainly by global warming, scientists say. Higher temperatures force corals to expel algae living in coral polyps which provide food and color, leaving white calcium skeletons. Coral dies in about a month if the waters do not cool.

Berkelmans said the Keppels had previously bounced back from bleaching once the waters had cooled. But if temperatures remained abnormally high then that would be much more difficult.

Many scientists say global temperatures are rising because fossil fuel emissions from cars, industry and other sources are trapping the earth’s heat. Experts worry some coral reefs could be wiped out by the end of the century.

Global warming could also damage corals by raising world sea levels by up to three feet by 2100. That could result in less light reaching deeper corals, threatening the important algae.

The Great Barrier Reef -- the world’s largest living reef formation stretching 1,250 miles north to south along Australia’s northeast coast -- was the first to experience what turned out to be global coral bleaching in 1998 and 2002.


Wider bleaching possible
The Keppels bleaching is as severe as those two events and scientists say the threat of widespread bleaching is moderate.

“Sea temperatures in all regions of the Great Barrier Reef are at levels capable of causing thermal stress to corals,” said the Great Barrier Reef Marine Park Authority’s February report.

The U.S. National Oceanic and Atmospheric Administration’s Coral Reef Watch said the 2005 Caribbean bleaching centered on the U.S. Virgin Islands, but stretched from the Florida Keys to Tobago and Barbados in the south and Panama and Costa Rica.

Reef Watch said sea temperature stress levels in the Caribbean in 2005 were more than triple the levels that normally cause bleaching and almost double the levels that kill coral.

“Time will tell whether there was large-scale mortality or not,” said Professor Robert Van Woesik from the Florida Institute of Technology in a statement issued by Australia’s Queensland University. He said corals did have some ability to bounce back but that this was an unusually warm event.

Timing raises concerns
Queensland University’s Professor Ove Hoegh-Guldberg, head of a group of 100 scientists monitoring bleaching, said scientists were concerned about how close in time the two severe bleaching episodes were.

“The 2006 Great Barrier Reef event comes soon after the worst incidence of coral bleaching in the Caribbean in October 2005,” said Hoegh-Guldberg who also went diving on the Keppels where he said damage was extensive.

“The traces suggest we are tracking the temperature profile of 2001-2002, which led to the worst incidence of coral bleaching ... for the Great Barrier Reef,” he said.

In 2002, between 60 and 95 percent of the reefs that make up the Great Barrier Reef were bleached. Most corals survived but in some locations up to 90 percent were killed.

Hoegh-Guldberg said projections from 40 climate models suggested that oceans would warm by as much as three to four degrees Celsius in the next 100 years.

“We’re starting to get into very dangerous territory where what we see perhaps this year will become the norm and of course extreme events will become more likely,” he said.

“The climate is changing so quickly that coral reefs don’t keep up ... the loss of that ecosystem would be tremendous.”

[artist]

I know someone with Harbor Branch Oceanographic Research and there is also a realtively new found species of star fish that are known for eating coral that is alive - they are killing thousands per day trying to get rid of them. Wish I had a link for the info but I don't.

[bvigal]

This is a valid concern for everyone. Please be a friend to our oceans and coral... so beautiful! Damage is not just from warm water, either. Pollutants and pesticides are a concern. And new things in water (bacteria, fungus, etc.) washed down rivers like Orinoco, Amazon from massive destruction of rainforests, traveling in currents across the Caribbean. The biggest concern here is from development - more and more and more hillsides being chopped up with bulldozers - it's alarming!

I can give some glint of good news, though. My friends who spend every single day diving say that once the waters clear (from washed down mud, etc.) and temps cool (winter), the coral comes back. Maybe not all of it, but maybe not quite as dire as I'd thought.

BVI's local chapter of reef loving protoectors: Association of Reef Keepers

[alicia-w]

I know someone with Harbor Branch Oceanographic Research and there is also a realtively new found species of star fish that are known for eating coral that is alive - they are killing thousands per day trying to get rid of them. Wish I had a link for the info but I don't.

Coral-eating starfish again threaten Okinawan waters
Posted: January 23, 2002

The onihitode, the crown-of-thorns starfish that eats live coral and that previously had wreaked havoc around Okinawa, is once again propagating in the vicinity of the Kerama Islands at an abnormally high rate of speed. Divers from Zamami Village have caught more than 10,000 starfish since the beginning of January, and the heaviest density of the destructive creatures in the last decade has been observed at Ishigaki, prompting calls for emergency measures. The onihitode swept through an extensive area that included Okinawa from the 1960s to the 1980s, destroying almost all the living coral that crossed its path. With the help of a subsidy from the government of Japan, local officials were able to exterminate over 2 million starfish between 1974 and 1998, when the subsidy ran out. Since then, prefectural officials have been monitoring Okinawan waters but have been unable to resume the campaign to destroy the predators due to a lack of funds.

I think that's the crown-of-thorns starfish. Nasty little bugger.