And some thought ocean acidification would destroy everything.
“We were surprised that some organisms didn’t behave in the way we expected under elevated CO2″…“They were somehow able to manipulate CO2…to build their skeletons.”
From the Wood Hole Oceanographic Institute press release, just in time for Copenhagen.
In a striking finding that raises new questions about carbon dioxide’s (CO2) impact on marine life, Woods Hole Oceanographic Institution (WHOI) scientists report that some shell-building creatures—such as crabs, shrimp and lobsters—unexpectedly build more shell when exposed to ocean acidification caused by elevated levels of atmospheric carbon dioxide (CO2).
Because excess CO2 dissolves in the ocean—causing it to “acidify” —researchers have been concerned about the ability of certain organisms to maintain the strength of their shells. Carbon dioxide is known to trigger a process that reduces the abundance of carbonate ions in seawater—one of the primary materials that marine organisms use to build their calcium carbonate shells and skeletons.
The concern is that this process will trigger a weakening and decline in the shells of some species and, in the long term, upset the balance of the ocean ecosystem.
But in a study published in the Dec. 1 issue of Geology, a team led by former WHOI postdoctoral researcher Justin B. Ries found that seven of the 18 shelled species they observed actually built more shell when exposed to varying levels of increased acidification. This may be because the total amount of dissolved inorganic carbon available to them is actually increased when the ocean becomes more acidic, even though the concentration of carbonate ions is decreased.
“Most likely the organisms that responded positively were somehow able to manipulate…dissolved inorganic carbon in the fluid from which they precipitated their skeleton in a way that was beneficial to them,” said Ries, now an assistant professor in marine sciences at the University of North Carolina. “They were somehow able to manipulate CO2…to build their skeletons.”
Organisms displaying such improvement also included calcifying red and green algae, limpets and temperate urchins. Mussels showed no effect.
“We were surprised that some organisms didn’t behave in the way we expected under elevated CO2,” said Anne L. Cohen, a research specialist at WHOI and one of the study’s co-authors. “What was really interesting was that some of the creatures, the coral, the hard clam and the lobster, for example, didn’t seem to care about CO2 until it was higher than about 1,000 parts per million [ppm].” Current atmospheric CO2 levels are about 380 ppm, she said. Above this level, calcification was reduced in the coral and the hard clam, but elevated in the lobster
The “take-home message, “ says Cohen, is that “we can’t assume that elevated CO2 causes a proportionate decline in calcification of all calcifying organisms.” WHOI and the National Science Foundation funded the work.
Conversely, some organisms—such as the soft clam and the oyster—showed a clear reduction in calcification in proportion to increases in CO2. In the most extreme finding, Ries, Cohen and WHOI Associate Scientist Daniel C. McCorkle exposed creatures to CO2 levels more than seven times the current level.
This led to the dissolving of aragonite—the form of calcium carbonate produced by corals and some other marine calcifiers. Under such exposure, hard and soft clams, conchs, periwinkles, whelks and tropical urchins began to lose their shells. “If this dissolution process continued for sufficient time, then these organisms could lose their shell completely,” he said, “rendering them defenseless to predators.”
“Some organisms were very sensitive,” Cohen said, “some that have commercial value. But there were a couple that didn’t respond to CO2 or didn’t respond till it was sky-high—about 2,800 parts per million. We’re not expecting to see that [CO2 level] anytime soon.”
The researchers caution, however, that the findings—and acidification’s overall impact—may be more complex than it appears. For example, Cohen says that available food and nutrients such as nitrates, phosphates and iron may help dictate how some organisms respond to carbon dioxide.
“We know that nutrients can be very important,” she says. “We have found that corals for example, that have plenty of food and nutrients can be less sensitive” to CO2. “In this study, the organisms were well fed and we didn’t constrain the nutrient levels.
“I wouldn’t make any predictions based on these results. What these results indicate to us is that the organism response to elevated CO2 levels is complex and we now need to go back and study each organism in detail.”
Ries concurs that any possible ramifications are complex. For example, the crab exhibited improved shell-building capacity, and its prey, the clams, showed reduced calcification. “This may initially suggest that crabs could benefit from this shift in predator-pray dynamics. But without shells, clams may not be able to sustain their populations, and this could ultimately impact crabs in a negative way, as well,” Ries said.
In addition, Cohen adds, even though some organisms such as crabs and lobsters appear to benefit under elevated CO2 conditions, the energy they expend in shell building under these conditions “might divert from other important processes such as reproduction or tissue building.”
Since the industrial revolution, Ries noted, atmospheric carbon dioxide levels have increased from 280 to nearly 400 ppm. Climate models predict levels of 600 ppm in 100 years, and 900 ppm in 200 years.
“The oceans absorb much of the CO2 that we release to the atmosphere,” Ries says. However, he warns that this natural buffer may ultimately come at a great cost.
“It’s hard to predict the overall net effect on benthic marine ecosystems, he says. “In the short term, I would guess that the net effect will be negative. In the long term, ecosystems could re-stabilize at a new steady state.
“The bottom line is that we really need to bring down CO2 levels in the atmosphere.”
The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment.
Alright… I ponied up $25 to the GSA and bought the paper.
18 benthic species were selected to represent a wide variety of taxa: “crustacea, cnidaria, echinoidea, rhodophyta, chlorophyta, gastropoda, bivalvia, annelida.” They were tested under four CO2/Ωaragonite scenarios:
409 ppm (Modern day)
606 ppm (2x Pre-industrial)
903 ppm (3x Pre-industrial)
2856 ppm (10x Pre-industrial)
7/18 were not adversely affected by 10x pre-industrial CO2: Calcification rates relative to modern levels were higher or flat at 2856 ppm for blue crab, shrimp, lobster, limpet, purple urchin, coralline red algae, and blue mussel.
6/18 were not adversely affected by 3x pre-industrial CO2: Calcification rates relative to modern levels were higher or flat at 903 ppm for halimeda, temperate coral, pencil urchin, conch, bay scallop and whelk.
3/18 were not adversely affected by 2x pre-industrial CO2: Calcification rates relative to modern levels were higher or flat at 903 ppm for hard clam, serpulid worm and periwinkle.
2/18 had very slight declines in calcification at 2x pre-industrial: Oyster and soft clam.
The effects on calcification rates for all 18 species were either negligible or positive up to 606 ppm CO2.
Douglas Haynes (01:55:27) :
I found your post really interesting, especially news of the existence of large-scale low-temperature hydrothermal vents ( aka warm-water-volcanoes) operating at fantastic pressures. I have a hunch that the chemistry of such systems and their hotter cousins is likely to be really significant, including their role in the formation of clathrates, oil, and mineral ore deposits. And, I hope that funding for research into such new discoveries is not being crowded-out by the AGW fad.
But on the use by AGWists of scary CO2 scenarios, I wonder about the fact that two oxygen atoms are used to form each molecule of CO2. So rather than worry about an Increase in atmospheric CO2, what about the appalling loss of atmospheric O2? Aren’t all animals, including Polar Bears and Kittens, in imminent danger of suffocation? How scary could THAT be?
@Chuck Booth (13:22:21) :
So… Increasing and decreasing calcification rates are both proof of ocean acidification? If everything proves a hypothesis, it is not falsifiable and therefore not scientific.
The coccolithophores have done A-OK for more than 100 million years. From Iglesias-Rodriguez et al., 2008…
They just happen to do better in a high-CO2 world. I’ll venture a guess that global warming has drowned more polar bears than it has coccolithophores.
David Middleton,
You have it backwards: Altered calcification rates are not proof of ocean acidification – they are a predicted consequence of acidification due to elevated pCO2. The evidence for ocean acidification is a measured reduction in ocean pH and alterations in carbonate concentration and calcite and aragonite saturation states. The decrease in pH so far is quite modest- about 0.1 pH unit- but the changes in carbonate chemistry indicate the buffering capacity of the ocean is being reduced by the rising pCO2. And, of course, any effects of ocean acidification are made more complex by gobal warming. Ocean acidification is explained in detail here:
http://www.ucar.edu/communications/Final_acidification.pdf
and in very simple terms here:
http://www.pmel.noaa.gov/co2/OA/
supercritical,
The oxygen in CO2 comes from organic molecules that are degraded in aerobic cell respiration and other metabolic pathways. There is no evidence that atmospheric oxygen concentration (or, more accurately, oxygen partial pressure) is decreasing. Please understand that, while CO2 has risen by about 100 parts per million (285 to 385) since the start of the industrial age, the concentration of oxygen in the atmosphere is 21%, or 210,000 parts per million.
I think the title of this article lead many people (judging by the comments posted) to jump to the conclusion that ocean acidification is good for calcifying organisms…they seem to just jump over the fact that it says SOME organisms in the title and they also ignore many of the points that the article makes.
Biological systems are complex and many factors interact in surprising and unexpected ways. This is part of what makes science interesting and exciting. If you go beyond the title of the article and read the content you find out that the researchers used optimal conditions to rear their organisms. Since nutrients (obviously) play a large role in how well an organism prospers, changes in nutrients (ie less than ideal conditions) could drastically change the results.
The article says they found 7 out of 18 organisms that created thicker shells. Even if these organisms are found to prosper in increased CO2 (and I don’t doubt that some organisms will be able to cope with increased CO2 levels), ecosystems are webs and organisms are interdependent. The article specifically points out one of the many possible interactions whereby crab are able to increase their shell output while their prey, a clam, decreases it’s output. Will crabs then increase the number of clams they eat (because the clams have a reduced defense?) What happens when crabs start eating more clams? Will the crab population increase? Do the clams go extinct? What does this do to the rest of the ecosystem (the organisms that live in the clam beds, the birds that eat the crabs etc.)? The ramifications could be huge both for the ecosystem and the fisheries that pull products from that ecosystem. This is why it’s important to ask the questions!
Also, there’s usually a biological “cost” to increased protections. Just like it takes us time and energy to create armor out of steel, it takes energy and resources for crabs and other organisms to create exoskeletons. If they’re making thicker skeletons, where are they getting extra energy and resources from? They have to come from somewhere, from increased foraging, from a reduction in reproduction etc. And again, what happens when food (resources) are scarce? Can they still maintain that extra growth?
There were several comments that criticized the article for mentioning future possibilities for research because they interpreted it as a way of asking for more grant money. I would argue instead that they were stating what they know within the limits of their experiment and mentioning ways for other scientists to broaden and explore the topic. This is part of good science!
I found the article to be informative and interesting and I, for one, look forward to future findings.
Thanks!
Of course, fossil fuel combustion also degrades organic molecules, resulting in the production of CO2, but the oxygen still comes from the organic molecules in the coal, oil, or whatever.
If the ocean acidification hypothesis simply predicts that all calcification rate changes, irrespective of the sign of the change, it’s no more of a scientific theory than Creation Science is.
There is no “measured reduction in ocean pH” over any significant time period. The only pH series that cover more than a few years that support ocean acidification are derived from pCO2.
Just cause I love Excel… Here’s a plot of Flinders Reef calcification rate and atmospheric CO2 from 1708-1988…
Flinders Reef Calc. Rate vs CO2
It’s kind of hard to see any adverse effect of pCO2 on the calcification rate of this reef.
NOAA has a library of dozens of coral reef calcification rates. I’ve only looked at a few; but none of the reefs that I’ve looked at, have declining calcification rates over the last 200+ years.
“Of course, fossil fuel combustion also degrades organic molecules, resulting in the production of CO2, but the oxygen still comes from the organic molecules in the coal, oil, or whatever.”
Chuck – I have really gotten a lot out of your comments on this thread, but this one really has me scratching my head. My car, a fossil fuel combuster, has an air intake to provide oxygen. Likewise coal-fired power plants, huge ones. What the heck to you mean here? – George
David Middleton: you are aware of the study on Australian coral from earlier this year, aren’t you?: http://tinyurl.com/yaqdse6
It’s not a direct proof of ocean acidification causing the slowing calcification, but its suggestive.
I read recently that coring of old Caribbean corals is underway now too, to check old growth rates.
I should add: I know this is a complicated area, and that the lab results on corals have been a real mixed bag. (From recollection, some corals take lower pH in their stride, others don’t. Some don’t die, but turn into soft bodied things.) Then you have the complicating factor of increasing water temperatures. (Again, from recollection – warmer water is generally good for corals, but too warm and they bleach and take some years to recover.) Increased acidification also has been shown to affect symbiotic algae that coral use too.
There is no doubt of life of some varieties will continue in lower pH seawater. The issue is, though, whether the mix of sea life will change (from plankton up) in such a way that hurts humans, or indeed the aquatic mammals (eg by affecting important fisheries.) Another scenario is that increased algal blooms could have have a detrimental effects. Nasty poisonous algal blooms are already a big enough problem in some areas.
As for unexpected ecological consequences, earlier this year I noted from a TV documentary that dying salmon in the upper streams of the North West American coast are now believed to be the most important source of nitrogen for the giant forests there. Although the show did not make the connection, I immediately thought that it must be a pessimistic but plausible chain of events then that acidified polar waters could mean less less fish food for salmon, which could even then affect the health of the forests. (Not to mention bears!)
That CO2 has become large enough to have effects on ocean life (as most scientists believe) therefore gives rise to considerable concern as to the ecological consequences, even though they are hard to predict with precision.
I’ve read the abstract and have some of his earlier papers. Most of the calcification data in the NOAA paleoclimatology library are from the author, Lough. The calcification data used by Pelejero at Flinders Reef was from Lough.
The recent decline in calcification rate is due to a decline in extension rate or linear growth. Calcification is calculated by multiplying density times extension. The density of the coral has not been affected. Furthermore, the calcification rate is still positive. The rate of growth has simply changed. This has happened quite frequently in the past.
The calcification rate of Flinders Reef (measured by Lough) declined by 35% from 1838 to 1868 and by 38% from 1888 to 1913. So a 14.2% decline in 18 years is hardly unprecedented in the last 400 years. The calcification rate actually increased by 60% from 1978 to 1988.
Science is not about what scientists believe, are concerned about or how they want to help the environment. Science is supposed to be an objective process of observation, hypothesis, testing, more observation and conclusions (where possible). That’s how theories are built. It’s not a process of forming a nebulous consensus around something that scientists are concerned about.
Coral bleaching is not harmful to reefs. It is fairly routine; bleaching events have been documented back to the 1870’s. It happens when hermatypic corals change out symbiotic zooxanthellae – Which happens quite often. Coral bleaching is commonly associated with El Niño events. Major bleaching episodes have been tied to major ENSO’s (1982-1983 and 1997-1998).
Geosota:
Yes, I botched my responses a bit. Let me see if I can dig myself out:
In aerobic cellular metabolism, oxygen is consume and CO2 is produced. But, the CO2 production occurs in the citric acid cycle (and an entry reaction to the citric acid cycle), whereas oxygen is used as a terminal electron acceptor, forming water (O + 2 e- + 2 H+ = H2O). Thus, the two oxygens in CO2 come from the oxygen atoms originally in the glucose molecule.
My mistake was applying to the combustion of fossil fuels, or methane – in those oxidations, yes, some of the oxygen combines with carbon to form CO2, while some oxygen forms water. Sorry for not thinking that through more carefully.
When combusting fossil fuels, and methane,
David Middleton,
“If the ocean acidification hypothesis simply predicts ….”
To what ocean acidification hypothesis are you referring? Can you provide a reference? I think you have erected a strawman here and are now busy beating it down.
As for pH measurements versus pH values derived from pCO2 (and alkalinity) measurements, are suggesting that the latter are not correct? If so, please explain why pH cannot be calculated this way – is there a problem with the Henderson- Hasselbalch equation?
Geosota et al,
Sorry for the typos in my last response. And I neglected to clarify my original response to supercritical by noting that, yes, the rise in atmospheric CO2 over the past 200 years has decreased the concentration of O2 in the atmosphere, but not by much: Supercritical correctly points out that each molecule of CO2 produced from fossil fuel combustion represents the removal of two molecules of oxygen- thus, the 100 ppm increase in CO2 should have caused a 200 ppm decrease in O2 concentration, which is only 0.1% – quite small. However, this calculation is complicated by the fact that there are other sources of atmospheric CO2, such as the burning of wood, which may have a different O2-CO2 stoichiometry. Plus, about half of the CO2 produced by fossil fuel combustion has been consumed in photosynthesis by plants and algae, which generates oxygen; the ratio of CO2 consumed to O2 produced, or photosynthetic quotient, depends on what molecules the plant is producing. Actual measurements of atmospheric oxygen concentration indicate a decline of 0.03% over the past 20 years, which is really quite negligible:
http://www.sciencedaily.com/releases/1999/07/990719033405.htm
For everyone pointing out that CO2 levels have been significantly higher in the past, yes it’s true. But, you all need to stop thinking on human timescales. In the cases where CO2 levels were thousands of ppm higher than modern levels, it took hundreds of thousands of years. That is ample time for marine organisms to adapt and evolve.
On the other hand, if current rates of increase remain as they are we will reach those upper levels of known CO2 in just hundreds of years. That is what really makes the difference. It’s a matter of rates. Stop taking things at face value and use your supposedly superior brains to really think about it.
And, yes, some of the organisms DID benefit from the elevated CO2 levels. Unfortunately, what the author of this article neglected to mention is that only 3 of those organisms continued to benefit. The other 4 experienced declining calcification rates after moderate CO2 increases.
“The bottom line is” that this is a very poorly written article when it comes to explaining the major results of the research. Ultimately, 15 of the 18 organisms were negatively impacted by the higher CO2 levels.
I must amend my previous post. 14 of the 18 were negatively impacted by the higher CO2 levels. The mussel experienced no changes at all CO2 levels.
David Middleton (20:09:36) :
“Just cause I love Excel… Here’s a plot of Flinders Reef calcification rate and atmospheric CO2 from 1708-1988…
Flinders Reef Calc. Rate vs CO2
It’s kind of hard to see any adverse effect of pCO2 on the calcification rate of this reef.”
Actually, the slope from 1890 to present looks negative, . . . as does that from 1770 to 1870 (and with about the same negative slope?),
. . . ‘but if we only show the data from 1890 on, then we might be able to hide the fact that the decline seems unrelated to the CO2 conc.’
(Also, note that prior to 1770, there may have been some decline, as well – it almost looks like coral have a roughly 100 year cycle where growth increases rapidly, then more and more slowly, then rapidly?)
“NOAA has a library of dozens of coral reef calcification rates. I’ve only looked at a few; but none of the reefs that I’ve looked at, have declining calcification rates over the last 200+ years.”
Was there supposed to be a list of them? I didn’t see any.
Isaac and others,
When referring to the “article” it is important to distinguish between the original research article by Ries et al in Geology, and the WHOI press release (reprinted by Watts Up With That, above). Ries et al were fairly cautious in the conclusion to their article:
“Our experiments suggest that the response of calcifying marine organisms to elevated atmospheric pCO2 will be variable and complex. However, with the data at hand, it is difficult to predict how these changes in calcification will impact organisms’ survival, reproductive success, and overall ecosystem health. Even those organisms showing enhanced calcification under elevated pCO2 could be negatively impacted by the decline of less CO2-tolerant species within their ecosystems. We have only begun to generate the data needed to assess CO2-driven impacts on organisms and ecosystems in the geologic past, and to anticipate the effects of anthropogenic ocean acidification in the decades and centuries ahead.”
That’s my point. Ocean acidification is used as a “catch all”. It really isn’t a theory or even a hypothesis as it is commonly used.
The geological theory of ocean acidification is that a sufficient decline in pH can cause the Carbonate Compensation Depth (AKA lysocline) to become shallower, or shoal. The CCD is the depth below which calcium carbonate dissolved faster than it accumulates. A CCD shoaling in the South Atlantic Ocean can be documented about 55 million years ago during the PETM; a period of near-extinction-level volcanism. Oceanic pH is estimated to have declined to ~7.4 for a period of time; however the connection between that acidification episode and CO2 is extremely tenuous.
This is something that can be tested. The CCD is either shoaling; or it isn’t. There is no evidence that the CCD is becoming shallower.
The Henderson–Hasselbalch equation is a fine way of deriving pH. As I said in an earlier post, the derivation might be correct. Using DIC, pCO2 and TA to derive K makes a lot of assumptions about CO2 and H2CO3.
The problem is in correlating a function of CO2 with CO2 and then saying that the correlation is meaningful. Particularly if you are asserting a linear relationship between CO2 and pH in light of the fact that all of the derived pH “declines” fall right in the middle of the oceanic pH range over the last 6,000 years.
That’s nonsense; the effects on calcification rates for all 18 species were either negligible or positive up to 606 ppm CO2. Only 2 species showed even a slight decline in calcification rate at 606 ppm (oysters and soft clams).
I have a copy of the paper right in front of me. 13 of the 18 had increasing or flat calcification rates out to 903 ppm. None of the species actually experienced dissolution until CO2 was jacked up above 903 ppm.
Chuck Booth (09:35:35) :
I don’t have the paper. Does he say anything in materials and methods, like about how he added the CO2, and if he used any artificial buffers in the water? Was it real sea water, or a lab concoction meant to simulate seawater? Were there, as DaveH (20:05:25) : said, bits of coral added (to supply the necessary Ca or Mg ions?)?
I know from experience that just a slight change in ambient culture conditions can drastically change the results of, in my case mammalian cell cultures. E.g., changing to a different lot# of bovine or equine serum supplement can erase an effect, as can changing to a different but “equivalant” medium. So I am VERY wary of any results produced in a lab, because there are so many artifacts that can result from an ever so slight change.
Here’s a link to NOAA’s coral search engine…
Coral and Sclerosponge Data Search
You can search by variable (pH, Calcification, etc.), site name, author, Lat/Lon, or country.