Study: CO2 "acidification" does not harm Coral


Guest essay by Eric Worrall

A study, pH homeostasis during coral calcification in a free ocean CO2 enrichment (FOCE) experiment, Heron Island reef flat, Great Barrier Reef led by researcher Lucy Georgiou has concluded that at least some Coral has the ability to regulate its own internal PH. This allows the studied coral to thrive, even in extreme acid environments.

From the conclusion of the study;

Importantly, individual nubbins exhibited near constant δ11B compositions along their major growth axis over each of the four growth periods measured, regardless of whether they were grown under treatment or control conditions (Fig. 2A and Fig. S4A). These near constant δ11B compositions equate to near constant internal pHcf (Fig. 2B and Fig. S4B), irre- spective of treatment and season and declined by less than 0.1 units per unit decrease in external pHsw (Δp Hcf =Δp Hsw= 0.067, P = 0.078, df = 36; Table S2 and Fig. 2B). This result reflects the ca- pacity of these coral to homeostatically maintain a pHcf of ∼8.4–8.6 at the site of calcification (Fig. 3) and thus near constant up-regu- lation of pHcf during the calcification process. As such, these findings are in marked contrast to earlier laboratory studies in which corals grown under stable and constant pH conditions exhibited a stronger sensitivity to ambient seawater pH, whereby pHcf decreased by up to 0.5 units for each unit decrease in ambient seawater pH. However, under the naturally and highly dynamic pH conditions within the Heron Island reef flat, corals seemingly exert a much stronger physiological control of pH, which overrides the seasonal ambient depression in seawater pH, as well as the super- imposed FOCE induced decrease in seawater pH. Reinterpretation (11) of previous laboratory work using P. cylindrica colonies under depressed pCO2 conditions (29) indicates that pH up-regulation was taking place at the site of calcification in this species; these previous experiments, however, kept CO2 constant throughout the experiment and therefore did not capture the dynamic nature of many natural reef environments.

Regardless, the ability of pH-homeostatic coral to survive and grow in these extreme pH environments may provide them with a greater resilience to the increased levels of ocean acidification expected to occur over the coming decades and centuries.

Lucy Georgiou led an intensive study into the resilience of coral to changes in CO2 level, which challenges many of the populist assumptions about coral and CO2. Her team also re-analysed the studies of other researchers, and worked out and stated why they think other researchers got it wrong. All this while working under the auspices of the University of West Australia, Lewandowsky’s old campus.


122 thoughts on “Study: CO2 "acidification" does not harm Coral

    • Not only her job.

      Abstract – 15 June 2012
      Resilience of cold-water scleractinian corals to ocean acidification: Boron isotopic systematics of pH and saturation state up-regulation
      Letter To Nature – 5 March 2012
      Coral resilience to ocean acidification and global warming through pH up-regulation

      • Someone else’s job may be on the ropes :

        “…. led by researcher Lucy Georgiou has concluded that at least some Coral has the ability to regulate its own internal PH.This allows the studied coral to thrive, even in extreme acid environments.”

        Say what ? Where did that come from ?
        Perhaps someone is not reading what is written carefully enough before paraphrasing it.

        Regardless, the ability of pH-homeostatic coral to survive and grow in these extreme pH environments

        Classic press release distortion of what a report REALLY said. Please note “extreme pH ” does NOT mean ” extreme acid “.
        In the context ‘extreme’ probably means pH 7.5 or 8.8 .

      • … with each nubbin having near-
        constant pHcf values independent of the large natural seasonal fluc-
        tuations of the reef flat waters (pH ∼7.7 to ∼8.3) or the superim-
        posed FOCE treatments.

        I wasn’t far off. In fact the full range of test conditions was still firmly alkaline.
        Since WUWT keeps blasting alarmists for calling less alkaline conditions “acid”, a correction to article would be in order, I think, Anthony.

      • Hah!
        Nice try Moik.
        Tell you guys your terminology is misleading and incorrect = Nothing but long winded arguments and steadfast insistence that it is legit.
        Use same terminology as you guys = Howls of protest and mock outrage at the gall to use same phrase in same context.
        Got any crocodile tears in your handbag of duplicitous nonsense?
        Are you serving cheese with your wine?

      • … Reef flat waters on Heron Island are also subject to strong diel variations that can change by up to 0.75 pH units within a 24-h period (Fig. S2) (9) …
        7.5 – 0.75 = 6.75 – true acid conditions, at least some of the time.

      • Thanks for picking up the issue Eric.
        However, the quotation that you provide does not say +/-0.75 , it cites that as total swing, and neither is it the range of conditions that they tested. Even accepting that range it is +/-0.375 pH.
        Even if your figure of 6.75pH was correct ( which it is not ) 6.75pH is not “extreme acid conditions” in anyone’s book, it is only just acid. It would probably be best if you simple correct the error. otherwise some warmist will be popping up saying WUWT says 6.75pH is extreme acid and why are they denying ocean acidification.
        It is important to be honest and consistent , not try to fight BS with BS, IMO.
        At least I’ve always seen its integrity and objectivity as the main reason for reading WUWT. Though it does seem to be getting less that way. I hope it does not become a “trend”.

      • Mike, I used “extreme” in the context of meaning a substantial deviation from what is considered normal, not int the context of say the acidity fuming sulphuric acid would produce. But you raise an interesting point about the use of language, and how it can lead to misinterpretations and imprecision.
        Why not create a story expanding on and exploring issues with the use of language, and submit it to Anthony as a climate story?

    • Eric, you mistranscribed “extreme pH” in the paper as “extreme acid” . A simple slip, that’s fine. A one word correction to the articel would be in order. It does not require me to write and article. There has been a very good one on just that topic here recently.
      There is nothing in the article that suggests either natural sea conditions or the test conditions ever got below 7.0pH.
      WUWT is constantly trying to counter this false use of “acidification” when referring to alkaline oceans. You mistake is undermining that effort.
      How about you just fess up and make a one work correction. No one will think less of you for doing so.

  1. I see the study is in the Great Barrier Reef. Well let’s see what has caused so much damage over the years. I see only 10% damage due to bleaching over 27 years prior to 2011/2. Some bleaching is caused by sunlight, freshwater inundation (low salinity) and poor water quality from sediment or pollutant run-off. Don’t forget El Nino (natural). What’s left for acid?

    Abstract – 2 October 2012
    The 27–year decline of coral cover on the Great Barrier Reef and its causes
    Tropical cyclones, coral predation by crown-of-thorns starfish (COTS), and coral bleaching accounted for 48%, 42%, and 10% of the respective estimated losses, amounting to 3.38% y-1 mortality rate. Importantly, the relatively pristine northern region showed no overall decline. …

    “The Great Barrier Reef has lost half its coral cover in the last 27 years. The loss was due to storm damage (48%), crown of thorns starfish (42%), and bleaching (10%) according to a new study published in the Proceedings of the National Academy of Sciences today by researchers from the Australian Institute of Marine Science (AIMS) in Townsville and the University of Wollongong.”
    “”There are three main sources for the coral decline, one is storms, however 42% is attributed to Crown of Thorns Starfish – and just 10% due to bleaching.”

    • “The Great Barrier Reef has lost half its coral cover in the last 27 years”
      Well according to which paper? Another paper one could quote says 19%, another 11%.
      Pull a rabbit out of a hat for a number. (It’s also worth noting that since coral is under the sea, it makes checking such numbers difficult, which is why you get such a spread in numbers-out of sight, out of mind).
      I’m guessing 0% of lost coral cover in the last 27 years, or perhaps some slight coral expansion with slight warming in the ocean.

      • Yeah I know Jimbo, the paper was not yours, I shouLD have made this clear when i quoted it.
        I just cant believe that no one openly challenges this rubbish, science is definitely not healthy when peer review fails to pick up gross distortions, the media fails to question it, journals don’t publish alternate views, and we get ‘50% of something’ which is more likely very close to zero.
        If it was a company director they would be fired or prosecuted for making this crap up

  2. Once bleaching has occurred, is it all over? Not necessarily. PS I vaguely recall corals evolved during a time of very high co2?

    Abstract – 2009
    Guillermo Diaz-Pulido et al
    Doom and Boom on a Resilient Reef: Climate Change, Algal Overgrowth and Coral Recovery
    …In 2006, mass bleaching of corals on inshore reefs of the Great Barrier Reef caused high coral mortality. Here we show that this coral mortality was followed by an unprecedented bloom of a single species of unpalatable seaweed (Lobophora variegata), colonizing dead coral skeletons, but that corals on these reefs recovered dramatically, in less than a year. Unexpectedly, this rapid reversal did not involve reestablishment of corals by recruitment of coral larva