Scientists see coral bleaching in the Northwestern Islands

Areas of bleached coral caused by warmer ocean temperatures were seen on the latest scientific voyage by federal scientists to the Northwestern Hawaiian Islands.

But scientists aboard a ship returning yesterday from waters in the Papahanaumokuakea Marine National Monument said although bleaching seems to be occurring more frequently, they haven't noticed any mass bleaching so far this year in the region.

September is usually the warmest month of the year, so a mass coral bleaching seems less likely this year, scientists said.

"We've dodged the bullet," said Peter Vroom, chief scientist on the voyage for the National Oceanic and Atmospheric Administration.

Thirty percent of the Kure atoll reef and one-fifth of the Pearl and Hermes atoll reef bleached, according to scientists who spent the past month on a research cruise in the Papahanaumokuakea Marine National Monument. Corals at other atolls inside the monument were unaffected.

"There were certain areas where the bleaching was kind of severe, where it was just a white carpet essentially," said Peter Vroom, chief scientist of the cruise, which returned to Oahu on Wednesday.

"Other areas you would see a coral head that's had a lot of color, but maybe a quarter of it would be white," Vroom said.

Mass coral bleaching occurs when unusually warm water prompts coral to expel algae, robbing the coral of needed oxygen and nutrients and eventually causing the reef to die. Corals may recover if the algae returns, but they're still significantly weaker and more vulnerable to disease.

Papahanaumokuakea chief scientist Randy Kosaki said one factor that appears to have reduced ocean temperatures and potential bleaching was the recent storm from the northwest that blew and stirred Hawaiian waters.

Overall, scientists say it's unclear what the long-term effect of this summer's bleaching will be. Corals in the monument - which account for 69 percent of all coral under U.S. jurisdiction - were exposed to only two weeks of slightly above normal temperatures.

Rusty Brainard (left), chief of the NOAA Pacific Islands Fisheries Science Center's coral reef ecosystem division, said coral starts dying after about two months of being exposed to higher-than-normal temperatures.

Brainard added that scientists were surprised when they found coral bleaching in some waters in the Northwestern Hawaiian Islands in 2002 and 2004.

But he said coral bleaching has become more frequent in recent years.

"The fact that now we're seeing it as a common event is one of those early indications the ecosystems themselves are changing," he said. "The Northwestern Hawaiian Islands are in this transition to some new state."

Scientists said the pristine waters in Papahanaumokuakea provide good conditions for researching the effects of global warming without human factors, such as pollution and tourism, intruding into a study.

"This is giving us a special opportunity to understand ... what are the impacts of climate change on reefs ... and what can we do to help coral reefs survive," said Heidi Schuttenberg, research coordinator for Papahanaumokuakea.

Schuttenberg said that earlier this year she visited Thailand, where mass bleaching has turned coral reefs white down to 60 feet. (Left: coral bleaching in Australia)

Schuttenberg predicted the bleached corals would be sick by the time scientists return for another research trip next year.

"When corals are bleaching, they're essentially starving," Schuttenberg said. "They're very weak so even if they survive their event, they're much more vulnerable to disease, and they have much lower reproductive capacity."

PAPAHANAUMOKUAKEA a World Heritage Site

Papahanaumokuakea consists of remote, mostly uninhabited atolls northwest of the main Hawaiian Islands and the waters surrounding them. The monument is the nation's single largest conservation area and is nearly 100 times larger than Yosemite National Park. President George W. Bush made the area a national monument in 2006.

It's home to 69% of the coral reefs in U.S. territory. It also hosts 7,000 marine species, a quarter of which are found only in Hawaii. The area is off-limits to fishing, allowing for healthy and abundant populations of sharks, ulua or jackfish, and other marine life.

Recently this year the Papahanaumokuakea Marine National Monument — a pristine haven for coral and other marine life, and a treasured site of ancient Hawaiian shrines — has been named a U.N. World Heritage site.

The area northwest of the main Hawaiian islands is the only U.S. location to make the list for both natural and cultural reasons, said monument spokesman Dan Dennison.

Haunani Apoliona, chairwoman of the Office of Hawaiian Affairs, said the listing will help preserve Papahanaumokuakea for future generations.

"We are very proud of this historic inscription," Apoliona said in a statement.

Source:
Star Advertiser, "Scientists see coral bleaching in the Northwestern Islands", accessed October 1, 2010
Kansas City.com, "Remote Hawaii atoll corals suffer some bleaching", accessed October 1, 2010
The News Chronicle,"Papahanaumokuakea Marine National Monument declared a World Heritage Site", accessed October 1, 2010

Extreme Heat Bleaches Coral, and Threat Is Seen

This year’s extreme heat is putting the world’s coral reefs under such severe stress that scientists fear widespread die-offs, endangering not only the richest ecosystems in the ocean but also fisheries that feed millions of people. (Left: bleached dying coral reef)

From Thailand to Texas, corals are reacting to the heat stress by bleaching, or shedding their color and going into survival mode. Many have already died, and more are expected to do so in coming months. Computer forecasts of water temperature suggest that corals in the Caribbean (right) may undergo drastic bleaching in the next few weeks.

What is unfolding this year is only the second known global bleaching of coral reefs. Scientists are holding out hope that this year will not be as bad, over all, as 1998, the hottest year in the historical record, when an estimated 16 percent of the world’s shallow-water reefs died. But in some places, including Thailand, the situation is looking worse than in 1998.

Scientists say the trouble with the reefs is linked to climate change. For years they have warned that corals, highly sensitive to excess heat, would serve as an early indicator of the ecological distress on the planet caused by the buildup of greenhouse gases.

“I am significantly depressed by the whole situation,” said Clive Wilkinson (left), director of the Global Coral Reef Monitoring Network, an organization in Australia that is tracking this year’s disaster.

According to the National Oceanic and Atmospheric Administration, the first eight months of 2010 matched 1998 as the hottest January to August period on record. High ocean temperatures are taxing the organisms most sensitive to them, the shallow-water corals that create some of the world’s most vibrant and colorful seascapes.

Coral reefs occupy a tiny fraction of the ocean (coral reef distribution map at right), but they harbor perhaps a quarter of all marine species, including a profusion of fish. Often called the rain forests of the sea, they are the foundation not only of important fishing industries but also of tourist economies worth billions.

Drastic die-offs of coral were seen for the first time in 1983 in the eastern Pacific and the Caribbean, during a large-scale weather event known as El Niño. During an El Niño, warm waters normally confined to the western Pacific flow to the east; 2010 is also an El Niño year.

Serious regional bleaching has occurred intermittently since the 1983 disaster. It is clear that natural weather variability plays a role in overheating the reefs, but scientists say it cannot, by itself, explain what has become a recurring phenomenon. (Left: map where potential coral bleaching may occur. Click on map for larger image)

“It is a lot easier for oceans to heat up above the corals’ thresholds for bleaching when climate change is warming the baseline temperatures,” said C. Mark Eakin, who runs a program called Coral Reef Watch for the National Oceanic and Atmospheric Administration. “If you get an event like El Niño or you just get a hot summer, it’s going to be on top of the warmest temperatures we’ve ever seen.”

Coral reefs are made up of millions of tiny animals, called polyps, that form symbiotic relationships with algae. The polyps essentially act as farmers, supplying the algae with nutrients and a place to live. The algae in turn capture sunlight and carbon dioxide to make sugars that feed the coral polyps.

The captive algae give reefs their brilliant colors. Many reef fish sport fantastical colors and patterns themselves, as though dressing to match their surroundings.

Coral bleaching occurs when high heat and bright sunshine cause the metabolism of the algae to speed out of control, and they start creating toxins. The polyps essentially recoil. “The algae are spat out,” Dr. Wilkinson said.

The corals look white afterward, as though they have been bleached. If temperatures drop, the corals’ few remaining algae can reproduce and help the polyps recover. But corals are vulnerable to disease in their denuded condition, and if the heat stress continues, the corals starve to death.

Even on dead reefs, new coral polyps will often take hold, though the overall ecology of the reef may be permanently altered. The worst case is that a reef dies and never recovers.

In dozens of small island nations and on some coasts of Indonesia and the Philippines, people rely heavily on reef fish for food. When corals die, the fish are not immediately doomed, but if the coral polyps do not recover, the reef can eventually collapse, scientists say, leaving the fishery far less productive.

Research shows that is already happening in parts of the Caribbean, though people there are not as dependent on fishing as those living on Pacific islands.

It will be months before this year’s toll is known for sure. But scientists tracking the fate of corals say they have already seen widespread bleaching in Southeast Asia and the western Pacific, with corals in Thailand (left), parts of Indonesia and some smaller island nations being hit especially hard earlier this year.

Temperatures have since cooled in the western Pacific, and the immediate crisis has passed there, even as it accelerates in places like the Caribbean, where the waters are still warming. Serious bleaching has been seen recently in the Flower Garden Banks, a marine sanctuary off the Texas-Louisiana border.

In Thailand, “there some signs of recovery in places,” said James True, a biologist at Prince of Songkla University. But in other spots, he said, corals were hit so hard that it was not clear young polyps would be available from nearby areas to repopulate dead reefs.

“The concern we have now is that the bleaching is so widespread that potential source reefs upstream have been affected,” Dr. True said.

Even in a hot year, of course, climate varies considerably from place to place. The water temperatures in the Florida Keys are only slightly above normal this year, and the beloved reefs of that region have so far escaped serious harm.

Parts of the northern Caribbean, including the United States Virgin Islands, saw incipient bleaching this summer, but the tropical storms and hurricanes moving through the Atlantic have cooled the water there and may have saved some corals. Farther south, though, temperatures are still remarkably high, putting many Caribbean reefs at risk.

Summer is only just beginning in the Southern Hemisphere, but water temperatures off Australia are also above normal, and some scientists are worried about the single most impressive reef on earth. The best hope now, Dr. Wilkinson said, is for mild tropical storms that would help to cool Australian waters.

“If we get a poor monsoon season,” he said, “I think we’re in for a serious bleaching on the Great Barrier Reef.” (coral from Great Barrier Reef at right)

Source:
The New York Times, "Extreme Heat Bleaches Coral, and Threat Is Seen", accessed September 21, 2010

Soaring temps cause mass coral killing in Indonesia: study

Coral reefs are suffering widespread damage in what is set to be one of the worst years ever for the delicate and beautiful habitats. A dramatic spike in ocean temperatures off Indonesia's Aceh province has killed large areas of coral and scientists fear the event could be much larger than first thought and one of the worst in the region's history.

The phenomenon, known as coral bleaching because the reefs turn bone white when the colorful algae that give the coral its color and food is lost, has been reported throughout south east Asia, the Indian Ocean and the Pacific.

High ocean temperatures this year are being blamed for the bleaching, which experts fear could be worse than a similar event in 1998 which saw an estimated 16 per cent of the world’s reefs being destroyed.

The coral bleaching -- whitening due to heat driving out the algae living within the coral tissues -- was first reported in May after a surge in temperatures across the Andaman Sea from the northern tip of Sumatra island to Thailand and Myanmar.

Divers and scientists have described huge areas of previously pristine reef being turned into barren white undersea landscapes off the coast of Thailand and Indonesia. An international team of scientists studying the bleaching event found that 80 percent of some species have died since the initial assessment in May.

More coral colonies were expected to die within the next few months and that could spell disaster for local communities reliant on the reefs for food and money from tourism.

Corals are a delicate combination of animal, algae and rock that form intricate undersea structures, providing shelter for thousands of brightly colored fish and also acting as nurseries for the young of many larger open sea fish. (At right: top reflects unbleached coral while bottom picture reflects bleached coral)

Coral reefs provide refuge and food to nearly a quarter of all marine species, making them among the most biologically diverse habitats on the planet. Bleaching can also rob fish and other species of important shelter and food sources.

"I would predict that what we're seeing in Aceh, which is extraordinary, that similar mortality rates are occurring right the way through the Andaman Sea," said Andrew Baird of James Cook University in Townsville, in the Australian state of Queensland.

If so, that would make it the worst bleaching recorded in the region, said Baird.

Scientists from the Wildlife Conservation Society and Syiah Kuala University in Aceh have also been assessing the damage. "This one of the most rapid and severe coral mortality events ever recorded," the U.S.-based WCS said in a statement.

It also fits a pattern of climate extremes, from heatwaves to flooding, that have hit many areas of the globe this year. Between April and late May, sea surface temperatures in the Andaman Sea rose to 34 degrees Celsius or about 4 degrees C above the long-term average, according to the U.S. National Oceanic and Atmospheric Administration's Coral Hotspots website.

SLOW RECOVERY

"Similar mass bleaching events in 2010 have now been recorded in Sri Lanka, Thailand, Malaysia and many parts of Indonesia," the WCS statement said.

Baird, of James Cook University's ARC Center of Excellence for Coral Reef Studies, stated that climate change could have played a role in the extreme ocean temperatures around Aceh.

"There might be one of these cyclic climate phenomena driving it but it's much more severe than you would predict unless there was something else forcing it, which is almost certainly global warming," he said on Tuesday.

The bleaching is a blow to local communities in Aceh still recovering from the 2004 tsunami. That disaster caused relatively little damage to reefs and Baird said some areas had showed a dramatic recovery.

Although reefs can often recover from bleaching, it leaves the coral vulnerable to damage from storms, infections and other environmental stress, increasing the risk of deaths.

Baird said reefs in Indonesia would normally take 5 to 10 years to recover from localized bleaching. But if the event was spread across a much wider area, recovery would take longer.

"I suspect the scale of this event is so large there is unlikely to be many healthy reefs in the rest of Aceh."

Coral Bleaching Study of the Great Barrier Reef

The Great Barrier Reef's (right) dominant coral species are among the most vulnerable to the effects of global warming according to a new research study.

A groundbreaking study into the immunity of coral species has found the iconic Acroporidae family to be among the most susceptible to outbreaks of disease or bleaching.

Acroporidae, also known as "reef building" coral for its role in the development of reefs, is among the most prevalent found in the Great Barrier Reef.

The branched structure and size of Acroporidae colonies (left) makes it among the most recognizable coral species in the world.

The study by scientists from James Cook University and the Australian Research Center ranked 17 coral species found on the reef according to their immunity.

It found species from the Acroporidae and Pocilloporidae (right) families ranked at the bottom of the scale, putting them at the most risk of bleaching or disease - both of which have been linked to global warming.

However, study leader Caroline Palmer said the Acroporidae corals were also among the fastest growing and most abundant species. They were, therefore, the most likely to survive as a species, even if individual colonies die.

"When a mass bleaching event hits they are one of the most affected species of coral but they seem to be bouncing back in a lot of places," she said. "They can reproduced faster so that when they are knocked back they can grow back a lot faster."

She said immunity levels appeared to be linked to the amount of energy a species assigned to it. Some, like the Acroporidae, (left) directed more energy towards growth reproduction, while other species had a slower growth rate but higher levels of immunity.

Source:
Reuters, "Soaring temps cause mass coral killing in Indonesia: study", accessed August 17, 2010
The Sydney Morning Herald, "Iconic coral species the most vulnerable", accessed August 17, 2010
Aquamarine Blog, "Coral reefs suffer mass bleaching", accessed August 17, 2010

Andaman Sea coral reefs hit by bleaching

Marine scientists have been closely watching massive coral bleaching in the Andaman Sea, believed to be the worst case in Thai waters for 20 years.

Coral reefs in the Andaman Sea off Phangnga, Krabi and Phuket, including popular diving sites such as the Similan, Phi Phi and Surin islands, have been damaged by the phenomenon.

The bleaching is likely to extend as far as Satun province, and could get worse if sea temperatures continue to rise, said Niphon Phongsuwan, a marine biologist at the Phuket Marine Biological Center (PMBC).

"The coral bleaching began happening last month. Five percent of the coral reefs affected by the phenomenon have already died. More coral will be damaged if the sea temperature remains high," said Mr Niphon.

"We are waiting for the rain, which can help cool down the sea temperature," he said.

The PMBC has been working closely with dive operators, who help monitor the coral bleaching situation. The phenomenon is also occurring in the Gulf of Thailand, such as in Rayong province, Mr Niphon said.

Scientists believe the main cause of coral bleaching is the warming of the oceans, which forces zooxantaellae, an algae which co-exists with the coral and gives it color, to detach from the corals' shell.

Strong sunlight can also kill the coral. The bleached coral reefs will take a long time to recover, according to Mr Niphon.

Coral reefs in shallow waters at depths up to 10m will take three to four years to recover. Coral in deeper seas will take more time to recuperate.

Somkiat Khokiattiwong, head of the PMBC's oceanography and environment unit, said high temperatures in the Andaman Sea and the central part of the Bay of Bengal were the likely cause of the massive coral bleaching.

The temperature in the Andaman Sea stood at 31-32C for a long period this year, making the sea warmer than the previous two years.

He believes the warmer-than-usual sea temperature is a consequence of the late onset of the monsoon over the Bay of Bengal and Andaman Sea. Monsoons usually arrive around mid-April. But this year, the rainfall came a little bit later than usual.

Burma and Malaysia could also face the coral bleaching problem in their waters, Mr Somkiat said.

The Andaman Sea is one of the country's most popular diving sites with around 80 sq km of coral reefs. It attracts millions of visitors and divers each year. Coral reefs in the Andaman Sea previously suffered severe bleaching in 1991 and 2003.


Source:
Bangkok Post, "Andaman Sea coral reefs hit by bleaching", accessed May 10, 2010