What Scientists Are Learning About the Impact of an Acidifying Ocean

Discussion in 'Conservation, Fishery Politics and Management.' started by agentaqua, Oct 10, 2017.

  1. agentaqua

    agentaqua Well-Known Member

  2. OldBlackDog

    OldBlackDog Well-Known Member

    The End of the Ocean Acidification Scare for Corals

    Paper Reviewed
    McCulloch, M.T., D'Olivo, J.P., Falter, J., Holcomb, M. and Trotter, J.A. 2017. Coral calcification in a changing world and the interactive dynamics of pH and DIC upregulation. Nature Communications 8: 15686, DOI:10.1038/ncomms15686.

    The global increase in the atmosphere's CO2 content has been hypothesized to possess the potential to harm coral reefs directly. By inducing changes in ocean water chemistry that can lead to reductions in the calcium carbonate saturation state of seawater (Ω), it has been predicted that elevated levels of atmospheric CO2 may reduce rates of coral calcification, possibly leading to slower-growing -- and, therefore, weaker -- coral skeletons, and in some cases even death. Such projections, however, often fail to account for the fact that coral calcification is a biologically mediated process, and that out in the real world, living organisms tend to find a way to meet and overcome the many challenges they face, and coral calcification in response to ocean acidification is no exception, as evidenced by findings published in the recent analysis of McCulloch et al. (2017).

    Writing in the journal Nature Communications, this team of five researchers developed geochemical proxies (δ11B and B/Ca) from Porites corals located on (1) Davis Reef, a mid-shelf reef located east-northeast of Townsville, Queensland, Australia in the central Great Barrier Reef, and (2) Coral Bay, which is part of the Ningaloo Reef coastal fringing system of Western Australia, in order to obtain seasonal records of dissolved inorganic carbon (DIC) and pH of the corals' calcifying fluid (cf) at these locations for the period 2007-2012. And what did those records reveal?

    As shown in the figure below, coral colonies from both reef locations "exhibit strong seasonal changes in pHcf, from ~8.3 during summer to ~8.5 during winter," which "represents an elevation in pHcf relative to ambient seawater of ~0.4 pH units together with a relatively large seasonal range in pHcf of ~0.2 units." These observations, in the words of McCulloch et al., "are in stark contrast to the far more muted changes based on laboratory-controlled experiments" (as shown in the dashed black line on the figure), which laboratory-based values are "an order of magnitude smaller than those actually observed in reef environments."

    With respect to DICcf (also depicted in Figure 1), McCulloch et al. report that the "highest DICcf (~ x 3.2 seawater) is found during summer, consistent with thermal/light enhancement of metabolically (zooxanthellae) derived carbon, while the highest pHcf (~8.5) occurs in winter during periods of low DICcf (~ x 2 seawater)."

    The proxy records also revealed that coral DICcf was inversely related (r2 ~ 0.9) to pHcf. Commenting on this relationship, the marine scientists say it "indicate that the coral is actively maintaining both high (~x 4 to x 6 seawater) and relatively stable (within ± 10% of mean) levels of elevated Ωcf year-round." Or, as they explain it another way, "we have now identified the key functional characteristics of chemically controlled calcification in reef-building coral. The seasonally varying supply of summer-enhanced metabolic DICcf is accompanied by dynamic out-of-phase upregulation of coral pHcf. These parameters acting together maintain elevated but near-constant levels of carbonate saturation state (Ωcf) of the coral's calcifying fluid, the key driver of calcification."

    The implications of the above findings are enormous, for they reveal that "pHcf upregulation occurs largely independent of changes in seawater carbonate chemistry, and hence ocean acidification," demonstrating "the ability of the coral to 'control' what is arguably one of its most fundamental physiological processes, the growth of its skeleton within which it lives." Furthermore, McCulloch et al. say their work presents "major ramifications for the interpretation of the large number of experiments that have reported a strong sensitivity of coral calcification to increasing ocean acidification," explaining that "an inherent limitation of many of these experiments is that they were generally conducted under conditions of fixed seawater pHsw and/or temperature, light, nutrients, and little water motion, hence conditions that are not conducive to reproducing the natural interactive effects between pHcf and DICcfthat we have documented here." Given as much, they conclude that "since the interactive dynamics of pHcf and DICcf upregulation do not appear to be properly simulated under the short-term conditions generally imposed by such artificial experiments, the relevance of their commonly reported finding of reduced coral calcification with reduced seawater pH must now be questioned."

    And so it appears that alarmist claims of near-future coral reef dissolution, courtesy of the ever-hyped ocean acidification hypothesis, have themselves dissolved away thanks to the seminal work of McCulloch et al. Clearly, the world's corals are much more resilient to changes in their environment than acidification alarmists have claimed them to be.
     
  3. GLG

    GLG Well-Known Member

    go to the source OBD..., go to the source, that's where you gain knowledge.
    https://www.nature.com/articles/ncomms15686

    In summary, we have now identified the key functional characteristics of chemically controlled calcification in reef-building coral. The seasonally varying supply of summer-enhanced metabolic DICcf is accompanied by dynamic out-of-phase upregulation of coral pHcf. These parameters acting together maintain elevated but near-constant levels of carbonate saturation state (Ωcf) of the coral’s calcifying fluid, the key driver of calcification. Although the maintenance of elevated but near-constant Ωcf in mature coral colonies is not directly influenced by ocean acidification, it is however highly susceptible to thermal stress. In extreme cases of coral bleaching, the loss of endosymbionts disrupts the metabolic supply of DICcf as well as the metabolites necessary to operate the Ca-ATPase that upregulate pHcf (refs 14, 34), thus effectively terminating calcification. So, although rising levels of pCO2 can have adverse effects on the recruitment and growth of juvenile corals35,36,37,38, especially those lacking robust internal carbonate chemistry regulatory mechanisms, extreme thermal stress is detrimental to all symbiont-bearing corals39,40 regardless of their growth stage. We therefore conclude that the increasing frequency and intensity of coral bleaching events due to CO2-driven global warming constitutes the greatest immediate threat to the growth of shallow-water reef-building corals, rather than the closely associated process of ocean acidification.
     
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  4. agentaqua

    agentaqua Well-Known Member

  5. OldBlackDog

    OldBlackDog Well-Known Member

    Survey, no science here, just non scientific opinions.


    A survey funded by Oregon Sea Grant has found that more than 80 percent of respondents from the West Coast shellfish industry are convinced that ocean acidification is having consequences on production.


     
    chromatose007 likes this.
  6. agentaqua

    agentaqua Well-Known Member

    I agree that the respondents dont have to be scientists - but I think it is a legit survey of shellfish growers.

    But as the survey states: "Of those who said they have been affected by ocean acidification, 97 percent reported financial damage and 68 percent reported emotional stress due to acidification."

    If 98% of beef farmers said their cows showed signs of mad cow disease - wouldn't one take that seriously???
     
  7. terrin

    terrin Well-Known Member

    As a past Albertan Premier once said "any self respecting farmer would just Shoot, Shovel and Shut Up. Lol.
     
    agentaqua likes this.
  8. OldBlackDog

    OldBlackDog Well-Known Member

  9. chromatose007

    chromatose007 Active Member



    This video featuring Professor Easterbrook, a US gov't scientist, covers a variety of climate change issues including ocean acidification. A bit long but, is very informative
    BTW: There is no such thing as 'fossil fuels'. We are burning hydrocarbons, of which there is little chance we will ever run out of.
     
  10. GLG

    GLG Well-Known Member

    From the video....... "You don't even what to know how much planning has gone into making sure the Great Barrier Reef look like sh#t."

     
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  11. agentaqua

    agentaqua Well-Known Member

  12. OldBlackDog

    OldBlackDog Well-Known Member

    chromatose007 likes this.
  13. GLG

    GLG Well-Known Member

    See post #10 for more funny....

    For others this is of interest.
     
  14. OldBlackDog

    OldBlackDog Well-Known Member

    chromatose007 likes this.
  15. OldBlackDog

    OldBlackDog Well-Known Member

    chromatose007 likes this.
  16. GLG

    GLG Well-Known Member

  17. OldBlackDog

    OldBlackDog Well-Known Member

    Last edited: Nov 9, 2017
    chromatose007 likes this.
  18. agentaqua

    agentaqua Well-Known Member

  19. spopadyn

    spopadyn Banned

    Well, it might surprise you, but on this the science is clear - the climate is changing due to human activity. Couldn't agree with you all more. The problem is this - what sacrifices are we going to make to stop the climate change? I attended a talk by Alan Greenspan on this exact issue. He estimated that the developed world would need to have a 40% reduction in there standard of living to just keep the climate neutral. This of course was predicated on the fact that we would need to allow China, India and other developing nations the ability to get to our standard of living. I have my doubts that we will all make that sacrifice....
     
  20. Birdsnest

    Birdsnest Well-Known Member

    I agree. I see it every day by myself and my peers who happen to be some of the most staunch climat change supporters I know of. Still willing to make the two long trips a year for their annual fishing and hunting trips. My community, Tofino is full of "Eco tourism" lavishing themselves as greener than the next guy in their day to day operations. For examlie there is a water taxi that does tours with twin 300's that has carbon neutral adventures written on the side of it. People traveling from all over the world to see Tofino is not carbon neutral. No way!
     

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