[Coral-List] Coral mortality in a warmer and acidified ocean

Dennis Hubbard dennis.hubbard at oberlin.edu
Fri Jan 27 11:38:01 EST 2017

Hi all:

I will have to keep this brief (I know how disappointed you all are), but
we may be conflating things a little too much. I spent most of my time at
the recent Ocean Sciences meetings in the acidification session. What
really stood out was that, even at pH levels equivalent to over 2000 ppm in
the atmosphere, the corals in sea-water talks maintained the pH levels
within their calcification space (caveat: not *Acropora*).

My take-away from this was, "good news, bad news". The good news was that
it seemed like corals had an incredible resilience and, on a short temporal
scale could "control their own destinies" with respect to acidification.
The bad news seemed to be two-fold. First, the resilience in these
experiments was related to pH - not the bleaching and disease that would
also accompany warming. Second, ion pumping comes at a high metabolic cost.
So, while this resilience may provide a short-term sheltering from
acidification, we should not forget that all the energy that goes into
maintaining pH in the calcifying space will undoubtedly take away from what
is available for reproduction, disease resistance, sediment removal and a
host of other "life skills".

So,while I am neither a coral physiologist nor a biogeochemist, I do not
see an inconsistency between a) warming (which triggers diseases, bleaching
AND acidification) and b) a lack of skeletal density in the geological
record. It could easily be as simple each colony maintaining high
calcification rates until the system catastrophically shuts down. Thus, the
geologic record would be telling us that "corals can adapt to bad
conditions until..... they can't" and, once they die, "they don't leave a
record at all" (good articles for the journal "Duh!"). In the words of
Conrad Neumann, "Nature is what nature is; science is what we think nature
is on any given day."


On Fri, Jan 27, 2017 at 10:45 AM, Risk, Michael <riskmj at mcmaster.ca> wrote:

> Fascinating, Gene.
> I await feedback from the rest of the 8,000-odd on the -list, those who
> are still able to respond after the recent political changes in your county.
> The implication, or the inevitable conclusion, is that the recent decline
> in Acropora has been caused by local stresses, not global change. This is
> something many in the reef community find hard to accept.
> Mike
> ________________________________________
> From: coral-list-bounces at coral.aoml.noaa.gov [coral-list-bounces at coral.
> aoml..noaa.gov] on behalf of Eugene Shinn [eugeneshinn at mail.usf.edu]
> Sent: January 25, 2017 12:43 PM
> To: coral-list at coral.aoml.noaa.gov
> Subject: [Coral-List] Coral mortality in a warmer and acidified ocean
> *In addition to the paper reviewed in the previous Coral-list here is A
> review published in the blog Co2 Science   Gene
> *
> *Paper Reviewed*
> Stolarski, J., Bosellini, F.R., Wallace, C.C., Gothmann, A.M., Mazur,
> M., Domart-Coulon, I., Gutner-Hoch, E., Neuser, R.D., Levy, O., Shemesh,
> A. and Meibom, A. 2016. A unique coral biomineralization pattern has
> resisted 40 million years of major ocean chemistry change. /Scientific
> Reports/ *6*: 27579, DOI: 10.1038/srep27579.
> Publishing their work in the journal /Scientific Reports/, the team of
> eleven international researchers compared the skeletal structures of
> living /Acropora/ corals with those of well-preserved fossil /Acropora/
> skeletons from the Eocene, Oligocene, and Miocene, noting that these
> latter organisms "have experienced major fluctuations in atmospheric CO2
> levels (from greenhouse conditions of high pCO2 in the Eocene to low
> pCO2 ice-house conditions in the Oligocene-Miocene) and a dramatically
> changing ocean Mg/Ca ratio." By doing so, it could therefore be
> empirically determined whether or not higher levels of CO2 (i.e., ocean
> acidification) truly are a detriment to corals, interfering with the
> process of calcification and disrupting or weakening skeletal structure.
> So is that what they found? Were these major reef building corals harmed
> by ocean acidification and temperature changes of conditions past?
> In a word, /no/. In stark contrast, in fact, Stolarski /et al/. report
> that "the most diverse, widespread, and abundant reef-building coral
> genus /Acropora/ (20 morphological groups and 150 living species) has
> not only survived these environmental changes, but has maintained its
> distinct skeletal biomineralization pattern for at least 40 My." Such
> "remarkable evolutionary stability," they continue, "exists despite
> major global geochemical fluctuations, from greenhouse (high pCO2)
> conditions and low seawater Mg/Ca (calcitic seas) in the Eocene to
> icehouse (low pCO2) conditions and rapidly increasing Mg/Ca (aragonite
> seas) during the Oligocene-Miocene."
> The take home message of the Stolarski /et al/. paper is that the
> skeletal formation process of /Acropora/ is, as they state, "strongly
> biologically controlled," uninhibited by changes in temperature or
> seawater chemistry, including seawater pH/ocean acidification conditions
> that are predicted to occur over the course of the next century and beyond.
> --
> No Rocks, No Water, No Ecosystem (EAS)
> ------------------------------------ -----------------------------------
> E. A. Shinn, Courtesy Professor
> University of South Florida
> College of Marine Science Room 221A
> 140 Seventh Avenue South
> St. Petersburg, FL 33701
> <eugeneshinn at mail.usf.edu>
> Tel 727 553-1158
> ---------------------------------- -----------------------------------
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Dennis Hubbard
Chair, Dept of Geology-Oberlin College Oberlin OH 44074
(440) 775-8346

* "When you get on the wrong train.... every stop is the wrong stop"*
 Benjamin Stein: "*Ludes, A Ballad of the Drug and the Dream*"

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