Acidifying Oceans Dramatically Stunt Growth of Already Threatened Shellfish, Research Finds

ScienceDaily — New research shows that global warming and its effects -- in particular, ocean acidification have descended upon shellfish reefs, particularly those formed by the Olympia oyster.

More than one-third of the world's human-caused carbon dioxide emissions have entered the oceans, according to Brian Gaylord, a biological oceanographer at the Bodega Marine Laboratory of the University of California at Davis.

"Similar to what happens in carbonated soda," says Gaylord, "increasing carbon dioxide in seawater makes it more acidic."

Even with small changes in acidity, seawater becomes corrosive to the shells of aquatic organisms.

That's not good news for most marine life, especially for oysters.

Gaylord is investigating the consequences of this increasing ocean acidity on the growth of larval and juvenile Olympia oysters native to the U.S. West Coast.

"Such early life stages can be extremely sensitive to environmental stresses like ocean acidification," says Gaylord.

"These stages operate as bottlenecks that drive overall population numbers. If larval and juvenile Olympia oysters decline as a result of an acidifying ocean, what does that mean for the species as a whole?"

Likely nothing good, he and colleagues say.

"Changes now happening in the ocean's chemistry are expected to continue far into the foreseeable future," says David Garrison, director of the National Science Foundation (NSF)'s biological oceanography program, which funds Gaylord's research. "They may have myriad effects on marine animals."

Gaylord conducted experiments on larvae and juveniles produced by adult oysters in Tomales Bay, California. Adults were collected in the bay, then held at the Bodega Marine Laboratory until they released larvae.

In the lab, the free-swimming larvae were reared into early juvenile life.

Carbon dioxide concentrations in laboratory seawater were controlled to match present-day conditions in the oceans, 380 parts per million (ppm), as well as two carbon dioxide scenarios projected to occur by the year 2100 (540 and 970 ppm).

Mid-way through the larval phase at day nine, oysters in the high carbon dioxide treatment had shells that were 16 percent smaller than those reared in control, or ambient, conditions.

These effects continued through the time the larval oysters settled onto hard substrate at day 12. Shell size was seven percent smaller for oysters in the 970 ppm treatment than in the control group.

By a week later, the effects were dramatically magnified. The bottom-dwelling juveniles in the 970 ppm treatment had grown 41 percent less than juveniles under control conditions.

The consequences persisted, even after the juveniles from all treatments had been returned to present-day conditions.

"One and a half months after being transferred back to normal seawater," says Gaylord, "juveniles that had come from the high carbon dioxide environment were still 28 percent smaller than oysters reared for the entire experiment in control conditions."

The results strongly suggest that the effects of ocean acidification on oyster larvae persist well into the juvenile phase, he says, with potential consequences for oyster populations.

"If similar impacts happen to species beyond the Olympia oyster, there could be repercussions for oysters around the world."

Globally, 85 percent of shellfish reefs have been lost, making oyster reefs one of the most severely threatened marine habitats on the planet.

"Shellfish reefs in some places are at less than 10 percent of their former abundance," says Garrison. "Oysters have gone extinct in many areas, especially in North America, Australia and Europe."

Just as coral reefs are critical to tropical marine habitats, shellfish like oysters are the ecosystem engineers of bays and estuaries, creating dwelling places for countless plants and animals that find refuge in their three-dimensional structure.

The surface area of an oyster bed across its dips and folds and crevices may be 50 times greater than that of an equally extensive flat mud bottom.

Shellfish reefs also provide important services to people by filtering water, and serving as natural coastal buffers from boat wakes, sea-level rise and storms.

Oysters have supported civilization for millennia, from the ancient Romans to railroad workers in California in the 1880s. In the 1870s, eastern oyster reefs extended for miles along the James River in Chesapeake Bay. By the 1940s, they had largely disappeared.

"It's unclear whether we will ever be able to return to that by-gone era," says Gaylord. "The constellation of environmental and other pressures on oysters--including the consequences of ocean acidification--places them at grave risk."

Gaylord and colleagues presented early results of their research at the Ocean Sciences Meeting in Portland, Oregon, in February. They plan to publish a paper with updated findings later this year.

Source: http://www.sciencedaily.com/releases/2010/04/100420152841.htm

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'Black Box' Plankton Found to Have Huge Role in Ocean Carbon Fixation

ScienceDaily — Scientists at the University of Warwick and the National Oceanography Centre in Southampton have opened "the black box" of eukaryotic phytoplankton and discovered that they actually account for almost half the ocean's carbon fixation by phytoplankton.

Carbon fixation by phytoplankton in the open ocean plays a key role in the global carbon cycle but is not fully understood. Until now researchers believed that cyanobacteria overwhelmingly accounted for phytoplankton's role in carbon fixation in the open ocean. But now scientists at the University of Warwick and the National Oceanography Centre in Southampton have opened "the black box" of eukaryotic phytoplankton and discovered that they actually account for almost half the ocean's carbon fixation by phytoplankton.

Blue-green algae, or cyanobacteria, grow in vast numbers in the sunlit surface waters of the oceans, the photic zone. They use sunlight to 'fix' carbon by converting carbon dioxide into sugars and other organic compounds through photosynthesis.

Cyanobacteria belong to the 'picophytoplankton', the tiniest phytoplankton. Until now they have been thought to dominate carbon fixation in the open ocean, with species belonging to the genera Prochlorococcus and Synechococcus being particularly abundant.

Like all bacteria, cyanobacteria are prokaryotes, distinguished from eukaryotes by the absence of a cell nucleus. However, although much less abundant than cyanobacteria, the photic zone also has a high biomass of small eukaryotic phytoplankton capable of carbon fixation.

"The eukaryotic phytoplankton community has long been a 'black box' in terms of its composition as well as contribution to carbon fixation," says Professor Dave Scanlan of the University of Warwick; "Determining how much carbon different groups fix into biomass is required for a full understanding of the Earth's carbon cycle," adds Professor Mikhail Zubkov of the National Oceanography Centre.

In research, published April 15 in the Journal of the International Society for Microbial Ecology, the scientists report how they measured carbon fixation by dominant phytoplankton groups in the subtropical and tropical northeast Atlantic Ocean, using samples collected from surface waters during a research cruise aboard the Royal Research Ship Discovery.

They discovered that eukaryotic phytoplankton actually fix significant amounts of carbon, contributing up to 44% of the total, despite being considerably less abundant than cyanobacteria. "This is most likely because eukaryotic phytoplankton cells, although small, are bigger than cyanobacteria, allowing them to assimilate more fixed carbon," says Zubkov.

Two groups of eukaryotes were distinguished, 'EukA' cells being more abundant but smaller than 'EukB' cells. Molecular techniques revealed that EukB largely comprised photosynthetic organisms called prymnesiophytes, most of which have never been cultured in the laboratory. Many of these are probably previously unknown species.

"Prymnesiophytes accounted for up to 38 per cent of total primary production in the subtropical and tropical northeast Atlantic Ocean," says Scanlan: "This suggests that they play a key role in oceanic carbon fixation, but this needs to be confirmed by widespread sampling from the world's oceans."

Zubkov recently showed that small eukaryotic phytoplankton can obtain carbon by feeding on bacteria, supplementing carbon fixed through photosynthesis.

It is likely that some of the organic carbon of prymnesiophytes and other eukaryotic phytoplankton is eventually exported from the photic zone to the deep ocean, rather than being returned to the atmosphere in the form of carbon dioxide.

"Given their clear importance, it is crucial that we now go on to understand the factors controlling growth of small eukaryotes in the oceans," concludes Scanlan.

Source: http://www.sciencedaily.com/releases/2010/04/100415085344.htm

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We are an international non-profit organization with members in over 60 countries, spanning 6 continents with 1 mission; healthy aquatic ecosystems free from human abuse and neglect. Oceanic Defense teaches people to protect our oceans by acting responsibly as consumers and by making smart decisions in our daily lives. Whether we are buying groceries, commuting to work, planning a vacation or advocating within our own communities; each action we take or decision we make either helps or hurts our oceans. We empower people to be part of the solution rather than part of the problem and work together to protect our blue planet.

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Measuring Carbon Dioxide Over the Ocean

The Norwegian weather ship Polarfront is equipped with a battery of instruments to measure wind speed, humidity and carbon dioxide. (Credit: Margaret Yelland (NOCS))

ScienceDaily — Reliable measurements of the air-sea flux of carbon dioxide -- an important greenhouse gas -- are needed for a better understanding of the impact of ocean-atmosphere interactions on climate. A new method developed by researchers at the National Oceanography Centre, Southampton (NOCS) working in collaboration with colleagues at the Bjerknes Center for Climate Research (Bergen, Norway) promises to make this task considerably easier.

Infrared gas sensors measure carbon dioxide based on its characteristic absorption spectra and are used to evaluate the air-sea flux of the gas. So-called closed-path sensors precondition air before measurements are made, while open-path sensors can be used to measure the air in situ.

One advantage of using open-path sensors at sea is that wind measurements can be taken contemporaneously in the same place. Moreover, because they are small and don't use much power they can be used on buoys.

"Open-path sensors have the potential greatly to increase our understanding of the variability of air-sea carbon dioxide fluxes," said PhD student John Prytherch of the University of Southampton's School of Ocean and Earth Science at NOCS.

However, a long-standing concern has been that the values from open-path sensors do not tally with those from closed-path sensors, or with measurements made using other techniques.

"Other scientists have been sceptical about the reliability of carbon dioxide flux measurements taken at sea using open-path sensors," says Prytherch: "However, we now believe that we understand the reason for the discrepancy and that we can correct for it."

The problem turns out to be that the sensors are sensitive to humidity, meaning that fluctuations in the amount of water vapour in the sample air skew the carbon dioxide measurements. This is probably caused by salt particles on the sensor lens that absorb water.

Having identified the problem, Prytherch and his colleagues developed and rigorously tested a novel method for correcting the data for the cross-sensitivity to humidity.

Data were collected aboard the Norwegian weather ship Polarfront, equipped with a battery of instruments to measure wind speed, humidity and carbon dioxide. Even the motion of the ship was monitored.

The researchers noted that the carbon dioxide fluxes calculated from open-path sensor data were clearly too high and affected by humidity. They were also very variable, suggesting that the effect is caused by salt on the optics, which accumulate before being washed off by rain. Indeed, the researchers were able to mimic this effect in the laboratory.

However, after correction using their newly developed method, the calculated carbon dioxide fluxes were in line with previous studies that used different sensors or techniques.

"This robust method opens the way for widespread use of open-path sensors for air-sea carbon dioxide flux estimation," said Dr Margaret Yelland of NOCS: "This will greatly increase the information available on the transfer of carbon dioxide between the air and sea -- information crucial for understanding how the ocean-atmosphere interaction impacts climate."

The work was supported by the United Kingdom's Natural Environment Research Council and is part of the UK SOLAS project HiWASE (High Wind Air-Sea Exchanges).

The researchers are John Prytherch, Margaret Yelland, Robin Pascal and Bengamin Moat (NOCS), and Ingunn Skjelvan and Craig Neill (Bjerknes Center for Climate Research, Bergen, Norway).

Source: http://www.sciencedaily.com/releases/2010/01/100119103555.htm

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How Arctic Food Webs Affect Mercury in Polar Bears

ScienceDaily — With growing concerns about the effects of global warming on polar bears, it's increasingly important to understand how other environmental threats, such as mercury pollution, are affecting these magnificent Arctic animals.

New research led by biogeochemists Travis Horton of the University of Canterbury and Joel Blum of the University of Michigan lays the groundwork for assessing current and future effects of mercury deposition and climate change on polar bears.

The study appears in the December issue of the journal Polar Research.

Mercury is a naturally occurring element, but some 150 tons of it enter the environment each year from human-generated sources such as coal-burning power plants, incinerators and chlorine-producing plants. Deposited onto land or into water, mercury is picked up by microorganisms, which convert some of it to methylmercury, a highly toxic form that builds up in fish and the animals that eat them. As bigger animals eat smaller ones, the methylmercury is concentrated -- a process known as bioaccumulation. Sitting at the top of the food chain, polar bears amass high concentrations of the contaminant.

Although that much is known, the details of how mercury moves through different food webs -- particularly in the Arctic, where snow and ice contribute to mercury deposition -- are not well understood. To tease out that information, Horton, Blum and co-workers studied polar bear hair samples from museum specimens collected in the late 19th and early 20th centuries, before mercury emissions from human-generated sources began to escalate.

By looking at three chemical signatures -- nitrogen isotopes, carbon isotopes and mercury concentrations -- the researchers learned that polar bears get their nutrition (and mercury) from two main food webs. At the base of one web are microscopic plants that float on the surface of the ocean (known as phytoplankton). The foundation of the second web is algae that live on sea ice.

The study showed that polar bears that get most of their nutrition from phytoplankton-based food webs have greater mercury concentrations than those that participate primarily in ice algae-based webs.

While it's tempting to speculate that declining sea ice, due to global warming, may force polar bears to depend more on phytoplankton-based webs, thus increasing their mercury exposure, the study doesn't directly address that issue. It does, however, provide other useful information, said Blum, who is the John D. MacArthur Professor of Geological Sciences and a professor of ecology and evolutionary biology.

"If you want to understand the potential effects of changing ecosystems on polar bears, you need to be aware of the existence of these two food webs, which may possibly be affected by sea ice," Blum said. "This work provides background information that will be important in our in-depth understanding of mercury bioaccumulation in polar bears."

In addition to Horton and Blum, the paper's authors are Zhouqing Xie, who was at U-M when the research was done and now is at the University of Science and Technology of China; Michael Hren, who was at Yale University when the work was done and now is a postdoctoral fellow at U-M; and C. Page Chamberlain of Stanford University.

Source: http://www.sciencedaily.com/releases/2009/12/091208170915.htm

Earth More Sensitive to Carbon Dioxide Than Previously Thought

The temperature response of the Earth (in degrees C) to an increase in atmospheric carbon dioxide from pre-industrial levels (280 parts per million by volume) to higher levels (400 parts per million by volume). (a) shows predicted global temperatures when processes that adjust on relatively short-term timescales (for example sea-ice, clouds, and water vapour) are included in the model (b) includes additional long-tem processes that adjust on relatively long timescales (vegetation and land-ice). (Credit: Image courtesy of University of Bristol)

ScienceDaily — In the long term, the Earth's temperature may be 30-50% more sensitive to atmospheric carbon dioxide than has previously been estimated, reports a new study published in Nature Geoscience.

The results show that components of the Earth's climate system that vary over long timescales -- such as land-ice and vegetation -- have an important effect on this temperature sensitivity, but these factors are often neglected in current climate models.

Dan Lunt, from the University of Bristol, and colleagues compared results from a global climate model to temperature reconstructions of the Earth's environment three million years ago when global temperatures and carbon dioxide concentrations were relatively high. The temperature reconstructions were derived using data from three million-year-old sediments on the ocean floor.

Lunt said, "We found that, given the concentrations of carbon dioxide prevailing three million years ago, the model originally predicted a significantly smaller temperature increase than that indicated by the reconstructions. This led us to review what was missing from the model."

The authors demonstrate that the increased temperatures indicated by the reconstructions can be explained if factors that vary over long timescales, such as land-ice and vegetation, are included in the model. This is primarily because changes in vegetation and ice lead to more sunlight being absorbed, which in turn increases warming.

Including these long-term processes in the model resulted in an increased temperature response of the Earth to carbon dioxide, indicating that the Earth's temperature is more sensitive to carbon dioxide than previously recognised. Climate models used by bodies such as the Intergovernmental Panel on Climate Change often do not fully include these long-term processes, thus these models do not entirely represent the sensitivity of the Earth's temperature to carbon dioxide.

Alan Haywood, a co-author on the study from the University of Leeds, said "If we want to avoid dangerous climate change, this high sensitivity of the Earth to carbon dioxide should be taken into account when defining targets for the long-term stabilisation of atmospheric greenhouse-gas concentrations."

Lunt added: "This study has shown that studying past climates can provide important insights into how the Earth might change in the future."

(a) shows predicted global temperatures when processes that adjust on relatively short-term timescales (for example sea-ice, clouds, and water vapour) are included in the model

(b) includes additional long-tem processes that adjust on relatively long timescales (vegetation and land-ice).

This research was funded by the Research Council UK and the British Antarctic Survey.

Souce: http://www.sciencedaily.com/releases/2009/12/091206162955.htm

Coral 'cryobank' saves reef species

SHOULD the Great Barrier Reef perish as a result of rising ocean temperatures and acidity levels, it appears scientists will have, at least, a small consolation prize.

The Zoological Society of London is planning the world's first coral "cryobank", which would preserve hundreds of samples of each species in liquid nitrogen.

Samples taken from the Great Barrier Reef would be included in the radical preservation effort, although none has so far been removed for this purpose.

For some marine scientists, however, the concept is deeply flawed since it fails to tackle the root of the problem -- the feared obliteration of coral reefs by mid-century.

Charlie Veron, former chief scientist of the Australian Institute of Marine Science, said he supported the effort but warned it was no consolation for the eradication of reefs.

Creating coral-style aquariums, similar to the zoos of today, or preserving the genetic make-up of coral samples to "resurrect" reef systems in the future, were not meaningful options, according to Dr Veron.

"These are not solutions," he said. "Because Australia is home to the biggest coral reef in the world, it should concentrate all its efforts into helping the Great Barrier Reef survive.

"Personally, I feel it's no compensation to know that the genetic information of corals is kept in machines."

Dr Veron said reefs across the globe would be wiped out by century's end if current trends continued.

"By mid-century, all shallow-water corals will have been wiped out by mass bleaching and by mid-century ocean acidification will be slowing or stopping the growth of corals on the Great Barrier Reef. Reef growth will have ceased."

As for the Great Barrier Reef -- said to be more biodiverse than all of Europe -- Dr Veron warned it would be "in tatters' by 2030.

"Young children today will see the Great Barrier Reef come to an end," he said.

The problem arises because most of the carbon in the atmosphere is taken up by the oceans where it is dissolved, forming carbonic acid.

This raises acidity levels and attacks the carbonate platform on which reefs are built, preventing corals from forming skeletons.

"Most carbon in the atmosphere is taken up by the oceans. A coral reef is a carbonate platform. They are made of carbonates and carbon dioxide directly attacks carbonates," Dr Veron said.

He said the solution to the problem was to reduce levels of carbon dioxide in the atmosphere.

"It's easy to stop. Stop producing carbon dioxide. We've got to cut the greenhouse emissions and that is what the Copenhagen meeting is all about," Dr Veron said.

Source: http://www.theaustralian.news.com.au/story/0,25197,26259162-5006786,00.html

Major US Shopping Chains Target Plastic Bags

By Bruce Horovitz, USA TODAY

Just in time for the holidays, reusable shopping bags are about to go decidedly mainstream.

Target (TGT), the fifth-largest U.S. retailer last year, will announce Monday plans to give customers a 5-cent discount for every reusable bag they use to pack their purchases.

The move comes within days of drugstore giant CVS' (CVS) plan to give participating CVS customers $1 cash bonuses on their CVS cards every four times they buy something but don't request plastic bags.

The programs come at a time retailers are feeling heat from advocacy groups, lawmakers and customers to take actions on environmental issues.

In tandem, the two programs could keep billions of plastic bags out of the environment and nudge other big retailers to take similar steps, says Allen Herskowitz, senior scientist at the Natural Resources Defense Council.

"Plastic bags are the most ubiquitous form of waste on the planet," Herskowitz says. "They are among the most deadly forms of marine debris, lethal to threatened species of marine mammals throughout the world."

For retailers, going green is the new gold.

"It's become part of the competitive landscape to demonstrate that it's part of your culture," says David Szymanski, marketing professor at Texas A&M University. "Retailers who want to connect with this generation have to go green."

Although smaller retailers — including Whole Foods (WFMI), Trader Joe's and regional grocer Stop & Shop — have given consumers financial incentives to re-use bags, most big retailers have stopped short of giving customers money to bring their own bags.

For the moment, at least, Wal-Mart, the world's largest retailer, has no plans to pay customers to use their own bags, spokesman Kory Lundberg says.

So the Target and CVS programs are raising eco-eyebrows.

The Target program, which will roll out on Nov. 1 at all 1,700 Target stores nationwide, could save billions of plastic bags. The chain posts upwards of 1.5 billion transactions annually — most ending up in more than one bag.

A pilot test in 100 Target stores earlier this year resulted in a hefty 58% reduction in plastic bags used, says Shawn Gensch, vice president of marketing. "The best-case scenario is that we'll have 100% success and every consumer will use a reusable bag."

The CVS program, rolling out to 7,000 stores over the next three weeks, requires customers wanting to participate to buy a 99-cent tag to be scanned with their CVS card.

"We reward customers for doing good things," says Melissa Studzinski, the chain's director of relationship marketing

Source: http://www.usatoday.com/money/industries/environment/2009-10-18-target-plastic-bags-green-environment_N.htm

Cabinet Ministers Illustrate Global Warming Issues

Maldivian President Mohammed Nasheed dos scuba gear as he signs a document in Girifushi, Maldives, on Saturday that calls on all countries to cut down their carbon dioxide emissions ahead of a U.N. climate change conference.

GIRIFUSHI, Maldives - Members of the Maldives' Cabinet donned scuba gear and used hand signals Saturday at an underwater meeting staged to highlight the threat of global warming to the lowest-lying nation on earth.

President Mohammed Nasheed and 13 other government officials submerged and took their seats at a table on the sea floor — 20 feet below the surface of a lagoon off Girifushi, an island usually used for military training.

With a backdrop of coral, the meeting was a bid to draw attention to fears that rising sea levels caused by the melting of polar ice caps could swamp this Indian Ocean archipelago within a century. Its islands average 7 feet above sea level.

"What we are trying to make people realize is that the Maldives is a frontline state. This is not merely an issue for the Maldives but for the world," Nasheed said.

As bubbles floated up from their face masks, the president, vice president, Cabinet secretary and 11 ministers signed a document calling on all countries to cut their carbon dioxide emissions.

Urgency
The issue has taken on urgency ahead of a major U.N. climate change conference scheduled for December in Copenhagen. At that meeting countries will negotiate a successor to the Kyoto Protocol with aims to cut the emission of greenhouse gases such as carbon dioxide that scientists blame for causing global warming by trapping heat in the atmosphere.

Wealthy nations want broad emissions cuts from all countries, while poorer ones say industrialized countries should carry most of the burden.

Dozens of Maldives soldiers guarded the event Saturday, but the only intruders were groupers and other fish.

Nasheed had already announced plans for a fund to buy a new homeland for his people if the 1,192 low-lying coral islands are submerged. He has promised to make the Maldives, with a population of 350,000, the world's first carbon-neutral nation within a decade.

"We have to get the message across by being more imaginative, more creative and so this is what we are doing," he said in an interview on a boat en route to the dive site.

Nasheed, who has emerged as a key, and colorful, voice on climate change, is a certified diver, but the others had to take diving lessons in recent weeks.

Three ministers missed the underwater meeting because two were not given medical permission and another was abroad.

Source: http://www.msnbc.msn.com/id/33354627/ns/world_news-weird_news/

Reefs could perish by end of century, experts warn

LONDON (Reuters) - Increasingly acidic oceans and warming water temperatures due to carbon dioxide emissions could kill off the world's ocean reefs by the end of this century, scientists warned on Monday.

The experts told a meeting in London the predicted pace of emissions means a level of 450 parts per million of carbon dioxide (CO2) in the atmosphere will be reached by 2050, putting corals on a path to extinction in the following decades.

The two dozen coral reef specialists and climate change exerts represented universities, government research offices and the Intergovernmental Panel on Climate Change.

"The kitchen is on fire and it's spreading around the house," Alex Rogers of the Zoological Society of London and the International Program on the State of the Ocean, said in a statement.

"If we act quickly and decisively we may be able to put it out before the damage becomes irreversible."

Oceans absorb large amounts of CO2 emitted by the burning of fossil fuels. But scientists say the oceans are acidifying as they absorb more carbon, disrupting the process of calcification used by sea creatures to build shells as well as coral reefs.

Researchers around the world have been urging governments to take more account of such threats to the oceans in a new U.N. treaty on fighting global warming due to be agreed in Copenhagen in December.

Coral reefs -- delicate undersea structures resembling rocky gardens made by tiny animals called coral polyps -- are important nurseries and shelters for fish and other sea life.

They also protect coastlines, provide a critical source of food for millions of people, attract tourists and are potential storehouse of medicines for cancer and other diseases.

PATH TO MAJOR DEGRADATION

"If CO2 is allowed to reach 450 ppm, as is currently widely regarded as being the most optimistic threshold target for world leaders to agree at Copenhagen, we will have put the world's reefs on a path to major degradation and ultimate extinction," John Veron, the former chief scientist of the Australian Institute of Marine Science, told the meeting.

"Such a catastrophe poses a dire threat to the future wellbeing of all humanity."

The scientists agreed that governments should strive for a level of 320 parts per million of carbon dioxide, saying 360 was a breaking point for reefs to survive.

At the current level of 387 parts per million of carbon dioxide, reefs are in serious decline, they said. This will have a future knock-effect that threatens other marine and coastal ecosystems.

Coral covers about 400,000 square km of tropical ocean floor, but needs sustained sunlight, warmer waters and high levels of carbonate to flourish.

The biggest is the Great Barrier Reef, a collection of 2,900 reefs along 2,100 km of Australia's north east coast in a marine park the size of Germany.

(Reporting by Michael Kahn; editing by Anthony Barker)

Source: http://www.reuters.com/article/scienceNews/idUSTRE5654JY20090706?pageNumber=2&virtualBrandChannel=0