ERODED REEF: Coral reefs find it hard to grow faster than they get washed away in the more acidic waters off the west coast of Panama—a potential precursor of their fate as the climate changes.
Image: COURTESY OF T.B. SMITH
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A new study confirms that coral reefs could become yet another casualty of climate change if something is not done to cool the warming globe. The reason: marine cements that bind together reefs can't form in waters full of dissolved carbon dioxide (CO2). Those off the west coast of Central America, particularly around the Galapagos Islands, are kept soft by the more acidic waters in that region—and may provide an early look at how coral reefs will fare in the rest of the world as atmospheric CO2 levels rise.
"The eastern Pacific is basically where the global ocean belches or burps. Thus, these waters have naturally occurring high CO2 and low pH" [an acidity/alkalinity scale; the lower the number the greater the acidity], says Derek Manzello, a biologist from the University of Miami and the National Oceanic and Atmospheric Administration's Atlantic Oceanographic and Meteorological Laboratory, lead author of the study appearing in Proceedings of the National Academy of Sciences USA. That makes the region "a natural laboratory to study how coral reef ecosystems are structured and function under these acidic conditions."
The sparse reefs off the coast of Central America face a host of tough conditions: cool waters that are rich in nutrients and also more acidic, courtesy of higher levels of dissolved CO2 from deep-sea microbes. Even Charles Darwin noted the absence of reefs in the area in his treatise on the subject.
So Manzello and his colleagues took samples from the reefs off the Galapagos and the west coast of Central America, along with those from other regions, such as the Bahamas where conditions are better for coral, and compared them. The analysis showed that acidic waters make it impossible for marine cement—limestone that precipitates out of the seawater as it flows against the coral reef—to form both between individual coral polyps as well as to anchor the entire reef ecosystem against the waves. "These results imply that coral reefs of the future may be eroded faster than they can grow," Manzello says.
These conditions mimic the ocean acidification that is already occurring as a result of elevated CO2 levels in the atmosphere from fossil fuel burning. "The pH of the global surface ocean has already decreased about 0.1 pH units since preindustrial times," Manzello notes. "This doesn't sound like much, but keep in mind that if a change of this magnitude occurred in the human blood stream, we would die."
The results are the first to analyze how a loss of marine cement might affect coral reefs in an acidified ocean. "Poor cementation will make reefs softer and therefore more vulnerable to erosion," says senior marine scientist Richard Aronson at the Dauphin Island Sea Lab in Alabama, who was not involved in the research. The geologic record offers potentially backing evidence as well, according to Aronson. There are some times in the geologic past when high acidity in the oceans goes along with poor reef-building, but in many cases it is not easy to establish a firm causal connection."
Short of controlling climate change, efforts to help the coral, such as providing reef structures, will not make up the difference either. "Artificial reefs are no match aesthetically, structurally or functionally to natural reef ecosystems," Manzello says. In other words, in a warmer world with more acidic oceans humans may not get the as much as $100,000 in economic benefits an individual reef can provide to a nearby community, according to one estimate, including that of protecting coasts against storms and supporting better fishing.
Adds Aronson: "We absolutely must control emissions of the principal greenhouse gas, carbon dioxide, if we are going to preserve life in the oceans in some approximation of the way it should be."
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7 Comments
Add CommentHi I read your magazines all the time all different ones. This article caught my interest. I was watching a TV program on Time by Sic. Dicovery. They said the coral in Pearl Harbor was still living with no defect from the bomb. I was thinking when I was watching this program, why can't scientists just inject out of them something that they have, that is keeping them alive and well with no defect from the bomb. These coral must have something, we don't have or produce. This article bothers me, it could be anything that is causing the water to be acidic. It is the pollution from boats,ships, people,garbage,sewage,and most of all oil spills. What could you do to make it more alkaline. Could you find an area that is more alkaline? Can you move the coral reefs to an area that is more alkaline? Can you find a secluded area and transplant the coral reef and treat them with more alkaline product something? Pauline Demkowicz paulinedemko@optonline.net 7/28/2008 11:57pm
Reply | Report Abuse | Link to thisYes, we should do something to protect our world!
Reply | Report Abuse | Link to thisDavid,
Reply | Report Abuse | Link to thisThe dangerous AGW theory surmises that, as atmospheric CO2 levels rise, the temperature will also rise. It further surmises that this will increase the temperature of the oceans. We know that water, as its temperature increases, holds less and less of any gas in solution. So, as the CO2 levels in seawater decrease as a result of global warming, the acidification of the seawater will likewise decrease, will it not?
Hence, no response of alarm to this story is required on our part? Indeed, in the light of this simple fact, one wonders what the conclusion of this story ought to be.
By the way, it would be more accurate to refer to "less alkaline" seawater than to "more acidic" or even, reprehensibly, "acidic". The sea cannot be acidic while its pH is above 7.
Cheers,
Richard Treadgold
Convenor
Climate Conversation Group
Paulinie unfortunatelly is not that simple to transplant coral reefs. These are complex ecosystem and in most cases are massive in size, so the idea of transplanting a reef is virtaully impossible. And you also have to consider that the hole ocean is getting more acid, so even if you could transplant it could be difficult to find another place to place it...And regarding your comment that it could be anything what is making the ocean more acidic, read below...
Reply | Report Abuse | Link to thisRichard the amount of CO2 that enters the ocean depends on the concentration on the atmosphere, if you raises the concentration in the atmosphere CO2 tends to enter the ocean (as occurs in the mayority of the ocean), while in upwelling areas with high CO2 concentration the ocean releases CO2 to the atmosphere. But one very important thing to take into account is that when CO2 enters the ocean only 1% remains as CO2; most dissociates into HCO3- and CO3-2, and the acid formed by dissolution of CO2 lowers the pH so that some of the CO3-2 combines to H+ to form HCO3-. Thus the addution of CO2 woiuld decreases the cocnentration of CO3-2. Furthermore, the concentration of CO3-2 determines de carbon saturation state, which determines if the calcium carbonate can precipitate or not; aragonite (corals) is more sensitive than calcite. Therefore a reduction in CO3-2 can affect the formation of coral reefs.
Juan,
Reply | Report Abuse | Link to thisWhat you say about CO2 is very interesting but the point concerns the temperature of sea water, not relative concentrations of CO2, nor the dissolving mechanisms.
The point is that, as the temperature of the water rises, all those ions are reassembled into CO2 again, which bubbles out of the water. Therefore we need not concern ourselves with the action on sea water of the subsequently decreasing carbonic acid. Need we?
When you refer to "de carbon saturation state" you really mean carbon dioxide, don't you?
Or have I missed something?
Can you say what is known about the rate at which carbonic acid is forming in the oceans? And how long it will take to descend to pH levels never reached before?
Finally, can you say what proof exists that any of the decline in pH is caused by human activity? For this is the important question; all else simply reports natural variability.
Cheers,
Richard Treadgold.
I used this article for my biology class, it was very helpful!
Reply | Report Abuse | Link to thisCO2 levels may have been over 2000ppm in 1200AD
Reply | Report Abuse | Link to thishttp://denialdepot.blogspot.com/2009/04/co2-levels-may-have-been-over-2000ppm.html
In other words, acidic seas are a good thing
http://www.seafriends.org.nz/issues/global/acid.htm
Corals have survived 300 million years of massively varying climate
http://www.sciam.com/article.cfm?id=ocean-acidif
How true!
"It would be more accurate to refer to "less alkaline" seawater than to "more acidic" or even, reprehensibly, "acidic". The sea cannot be acidic while its pH is above 7."
But that is not as scary is it? When Science tries to sell you a point like that it only makes people with any intelligence suspicious and wary of the Science,Just like you can pick a dodgy car salesman attempt at hoodwinking you.
Old but some things never change!
"Science Under Siege"
Case histories of how the media can be manipulated by pressure groups.
Doesn't this sound farmilar?
Global Warming,Worse than expected,Unprecedented,At an larming rate,dramatic increase,
The second Co2 threat,Oceans in Jeopardy,
http://www.fumento.com/science.html
"Thoroughly researched, heavily documented, and compusively readable, Science Under Siege carries a powerful message that this nation cannot afford to ignore. Here is compelling evidence that many terrors of the day have been wildly exaggerated – even fabricated – by environmental activists, politicians, the bureaucracy, and the media"
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Just like the Hockey Stick Deception....? ___________/1998 Pheww!
Warm_periods of Past 5000 years Temperatures
http://www.greenworldtrust.org.uk/Science/Images/Main/Warm_periods.jpg
/\__________/\__________/\___________/\2009 Brrrrrr!