REEFER SADNESS: Massive Porites coral, like the one pictured here, in the Great Barrier Reef are not growing as much anymore, most likely because of warmer and more acidic seawater.
Image: Courtesy of Jurgen Freund of Freund Factory
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The largest coral reef system in the world—and the biggest sign of life on Earth, visible from space—is not growing like it used to. A sampling of 328 massive Porites coral (large structures resembling brains that are formed by tiny polyps) from across the 133,000-square-mile (344,000-square-kilometer) reef reveals that growth of these colonies has slowed by roughly 13 percent since 1990.
The most likely reason is climate change caused by increasing carbon dioxide (CO2) and other greenhouse gases in the atmosphere, according to a new paper published today in Science.
The burning of fossil fuels over the past century or so has driven atmospheric CO2 levels from 280 parts per million (ppm) to 387 ppm—and growing. More than 25 percent of this extra CO2 is absorbed by the world's oceans and reacts with seawater to form carbonic acid. A rising carbonic acid level means a more acidic ocean.
And a more acidic ocean is bad news for coral and other sea creatures, which form their shells from calcium carbonate they extract from seawater. The more acidic the water, the more difficult it is to build the shells in the first place—as well as keeping them from dissolving.
To probe how corals are faring, marine biologist Glenn De'ath and colleagues at the Australian Institute of Marine Science in Townsville, Queensland, examined Porites coral samples stretching as far back as 1572. Because Porites lay down annual layers—like tree rings—changing environmental conditions are etched into their skeletons.
The record has not been good in recent years: Since 1990 coral have been extending and thickening by less and less each year. "The data suggest that such a severe and sudden decline in calcification is unprecedented in at least the past 400 years," the researchers wrote.
"This study put all this worry and discussion [about ocean acidification] into a real-world context," says marine biologist John Bruno of the University of North Carolina at Chapel Hill. "It shows that coral growth is indeed slowing—over a huge range and at many reefs—potentially due to increased acidity."
Slower growth will mean both that existing coral will find it difficult to cope with escalating acidity and rising sea levels. This will have enormous knock-on effects in sea life that relies on coral reefs for habitat—as well as human fisheries and other ecosystem services.
In the meantime, it appears that changes in sea temperatures and increased acidity are already beginning to impact the Great Barrier Reef. "Our data show that growth and calcification of massive Porites in the Great Barrier Reef are already declining and are doing so at a rate unprecedented in coral records reaching back 400 years," the researchers wrote. "These organisms are central to the formation and function of ecosystems and food webs, and precipitous changes in the biodiversity and productivity of the world's oceans may be imminent."
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12 Comments
Add CommentCoral growth has been sluggish since 1990 due to an increase in both sea temperature and acidity as a result of global warming
Reply | Report Abuse | Link to thisAcclaiming global warming as a cause with no articulated reference to the same is too mantric. This type of subjective article is not science. I might as well be reading Time magazine.
Sorry folks, just like the DDT-causes-raptor-egg-shell-thinning theory has been debunked, the atmospheric-CO2-causes-ocean-acidification-and-decalcification theory has been demonstrated to be inaccurate. Apparently the people you interviewed aren't staying current with the latest science.
Reply | Report Abuse | Link to thisSo what is the change in PH level in the areas suspected to have increased in acidity? That would be far more pertinent to the point being made than a tenuous correlation with CO2 levels in the atmosphere. You mentioned that CO2 absorbed by the oceans causes acidification, but you didn't exactly tell us how much the acidity has increased. Has it really? Or is that just an extrapolation based on the theory that atmospheric CO2 increases acidity of the oceans?
So here is a statement by laurenra7 that offers no supporting evidence. Statements like 'like DDT causes egg shell thinning theory has been debunked'. No reputable scientist has challenged that conclusion. The research clearly shows that with the use of DDT which started in the 1940's caused the precipitous decline in bald eagles and peregrine falcons in particular through 1972 when use of DDT was curtailed. Both of these raptors have seen a gradual population increase to the the tens of thousands there are at today. This is verifiable and not that result of some empty asertion, by a nonscientist or a self-serving pesticide industry advocate.
Reply | Report Abuse | Link to thisLaurenra7 is also spreading misinformation about the atmosheric CO2 ocean acidification decalcification theory. This critic attacks the article for not stating how much the acidification has increased. This critic strikes me as one of those that will attack blindly and as usual without any clear reason for doing so. In fact the increase in acidification is an easily verified measurement. But you do necessarily find that detailed info in a short article like this. For that you have to go a science article specifcally on that subject. For example even if you keyword 'correlation of carbonic acid increase in ocean water and increased coral mortality' you are likely to find substantial research info at publications such as Nature and Science.
Well said Bodhi. Correlation between increased atmospheric CO2 and ocean acidification is well established. It is beyond doubt in the scientific community. It is also known, through observation and laboratory experiments, that decreased pH levels effect many organisms, including coral. The NSF also has studies to this effect. Check out their website and read a few of the reports.
Reply | Report Abuse | Link to thisUnfortunately, many people seem to read blogs or general information on the web and accept it as scientific fact, rather than reading actual scientific journal articles. Today people are more likely to read things like Junk Science, whose creators have done no research themselves and can say virtually anything they want.
Perhaps it would be good to do a little light reading before you presume to respond knowledgeably about DDT (and about ocean acidification as well). If you peruse the literature you will find that other stress factors were tied to egg shell thinning and population decline: human encroachment, habit destruction, calcium deficiency, heavy metals, even noise. What caused the population increase in the U.S. was the protection of several species of raptors in the 70's. DDT is finally making a moderate comeback because people who weren't distracted by the noise of the irrational Ban-DDT mob in the 60's and 70's revisited the studies and found out it's one of the most benign and effective insecticides every invented. In 1970, the US National Academy of Sciences estimated that DDT saved more than 500 million lives while it was used.
Reply | Report Abuse | Link to thisBefore we start using big words like 'misinformation' about the atmospheric CO2 and ocean acidification decalcification theory, it might be good to, as mentioned above, do a little light (or heavy) reading. It's easy to find peer-reviewed papers on the Internet. Try the sites that don't necessarily agree with your preconceived ideas. You will see that, just like the atmospheric-CO2-global-warming theory, it seems plausible in a controlled, closed environment, but in the real world it has been demonstrated to be inaccurate.
It's clear that pH levels affect all kinds of organisms. The question is what levels? The article did not say. It only made vague references to CO2 concentrations in the atmosphere and inferences that somehow ocean acidity was increasing which was causing coral reef decline. Numbers and real data, if you please; not sweeping and possibly unrelated generalizations.
http://www.aims.gov.au/docs/media/news2009/20090102.html
Reply | Report Abuse | Link to thisLaurenra, please before you start making sweeping generalizations of your own, perhaps follow your own advice and do a little more heavy reading for yourself. In this article it will answer your question on the PH levels.
Laurenra you've done your homework first and are intelligent enough to pick the difference of what's rubbish and what's fair dinkum unlike some.
Reply | Report Abuse | Link to thisScience has become political and results are persuaded by grant's that have strings attached,so you need to have the intelligence to sort the real Science from the junk science as you have managed to.
http://www.jennifermarohasy.com/blog/archives/cat_coral_reefs.html
In fact,"Corals track-record is impressive. Corals have survived 300 million years of massively varying climate both much warmer and much cooler than today, far higher CO2 levels than we see today, and enormous sea level changes. Corals saw the dinosaurs come and go, and cruised through mass extinction events that left so many other organisms as no more than a part of the fossil record.
Corals are particularly well adapted to temperature changes and in general, the warmer the better. It seems odd that coral scientists are worrying about global warming because this is one group of organisms that like it hot. Corals are most abundant in the tropics and you certainly do not find fewer corals closer to the equator. Quite the opposite, the further you get away from the heat, the worse the corals. A cooling climate is a far greater threat."
Oh! and some sugested reading here!
Reply | Report Abuse | Link to thisAre oceans becoming more acidic and is this a threat to marine life?
By Dr J Floor Anthoni
http://www.seafriends.org.nz/issues/global/acid.htm
The most important limiting factor in aquatic ecosystem is the dearth of hydrogen ions (H+), which has also been overlooked. The more acidic the water, the higher biological productivity becomes, and the denser the amount of life. In the sea this is borne out by the observed fact that highly productive upwelling areas are more acidic. In other words, acidic seas are a good thing
rjzah,Aquestion,Where is the rising sea surface temperatures that your link
Reply | Report Abuse | Link to thisis trying to have us believe?See what I mean about the political state of Science at the moment.
http://jennifermarohasy.com/blog/wp-content/uploads/2009/01/gbr_stt1.gif
Barry,
Reply | Report Abuse | Link to thisYou have so much misinformation here, I'm not sure where to start. You have a fundamentally flawed impression of corals. Yes, corals thrive at relatively high temps (high 20's degrees C Though they thrive right next to there maximum thermal tolerance. Raise the temp a couple degrees C for any long period of time (usually over 30 or so) and you have coral bleaching which you apparently haven't heard of. Give the people who study these things some credit. You lack any coral physiological knowledge yet stake claims that contradict hundreds upon hundreds of peer reviewed literature on the subject over the last 20 years.
I advise you to read a paper by a well known coral taxonomist/biologist by the name of J Veron. The paper is regarding 'reef gaps' during past coral extinctions. He goes to analyze the current literature and infer what may have caused these trends. I think you may be surprised at the results to ocean acidification and temperature rise
http://www.springerlink.com/content/085g2151l3nlt871/
You also apparently, aren't in the science field. I am, however. Science is not the conspiracy you make it out to be. Grants are always competitive, and hot topics of funding come and go. The difference is, the findings of your study are subject to peer review. If you try to assert claims out of the scope of your work, peer reviewing 'usually' catches this and you must make rewrites. And unless your funding comes from Exxon, they're not going to censor or have any sort of agenda if you findings and methods are sound.
Both links you gave are horribly inaccurate. Its a red flag when someone has there own 'theories' about why the vast majority of scientists are wrong but have absolutely no peer reviewed literature to substantiate their hair brained ideas. If you want to read what real scientists are publishing on the subject take a look here
http://www.int-res.com/articles/theme/m373_ThemeSection.pdf
and here
http://www.ucar.edu/communications/Final_acidification.pdf
Shoreliner11,Are you really that nieve?
Reply | Report Abuse | Link to thisFor starters peer reviewed literature means diddly squat with the politicised so called science these days! They even resort to peer reviewing each oyhers papers,thats how much of a farce it all is.
The Disturbing corruption of the peer-review process
IPCC Peer Review Process an Illusion, Finds SPPI Analysis
Business Wire , Sept 10, 2007
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WASHINGTON -- Published by the Science and Public Policy Institute (http://scienceandpublicpolicy.org), climate data analyst John McLean has written an analysis of the reviewer comments to the UN's most recent IPCC Assessment Report released in April.
In "Peer Review? What Peer Review?" McLean writes, "The IPCC would have us believe that its reports are diligently reviewed by many hundreds of scientists and that these reviewers endorse the contents of the report. Analyses of reviewer comments show a very different and disturbing story."
More here.
A Major Deception on Global Warming by Frederick Seitz
http://www.sepp.org/Archive/controv/ipcccont/Item05.htm
For seconds, It's been at least six years since any average temperature rise and more than likely another 30to 60 yr mini ice age on the doorstep,
For three,Sunscreen worn by who knows how many visitors to the reef is more likely to have caused any bleaching.
Sunscreen Causes Coral Bleaching
http://www.onearth.org/blog/whats-happening-on-earth/sunscreen-causes-coral-bleaching
I hate to say this but, you have no idea what you're talking about. Do not think because you misunderstand a single article related to corals you know anything about their biology.
Reply | Report Abuse | Link to thisTry reading the whole article about coral bleaching. In no where does it state sunscreen is as you put, "more likely to have caused bleaching" than any other factor. The article does quote this though, "Bleaching, induced by changing ocean temperatures, pollution, and bacterial pathogens, is the process in which hard coral loses its alluring tenants, leaving behind bare, whitish rock." And then goes on to state the effects of sunscreen.
However, you trying to say that there was enough sunscreen lathered people across the entire Pacific Ocean in 1998 to cause the largest mass coral bleaching event in recorded history? Get real! Its not only not possible, but foolish to think so. If you look at the actual literature on the subject you'll find out the truth on coral bleaching.
Regarding the IPCC, peer reviewed is just that. Review by your peers. When you take 2000 of the world's top climate scientists and they collectively publish a paper, they are effectively the ones who would otherwise be peer reviewing the paper. They are the ones who peer review papers for other journals in that field after all.
Secondly, SPPI has a horrible track record for providing a common 'denier' perspective which characteristically spreads dissinformation, misquotes science papers, etc. By the way, any non-profit that has Chris Monckton on its staff list, just summed up where its profits are coming from (even though they won't disclose any of that information to the public) and the agenda they have.
And why even include the link by Frederick Seitz? ITS 13 YEARS OLD!!! Despite the fact that it shows their denying of the science is consistent through the years.
If you ACTUALLY want to know about coral bleaching, look to where actual science is published.
http://apps.isiknowledge.com/summary.do?qid=4&product=WOS&SID=4AmOLgebgadpAMH93ne&search_mode=GeneralSearch
I'm done posting anything to refute your asinine claims.