[Coral-List] Fwd: So you think you understand coral bleaching?

Dennis Hubbard dennis.hubbard at oberlin.edu
Sun Apr 5 21:56:57 UTC 2020

Hi DOug:

I think that the recent Coronavirus situation has illustrated two things to
think about. First is the "all your eggs in one basket" mentality that you
have discussed well already; I've already posted too many times about my
problems with breeding "genetic super-corals". Second, and surprising to
me, is that the lowered travel related to Coronavirus is apparently already
having measurable effects on the amount of "greenhouse gasses" in the
atmosphere - particularly CO2. What might this be telling us about  the
physics involved and the management options we might think more about?


On Sun, Apr 5, 2020 at 2:23 PM Douglas Fenner via Coral-List <
coral-list at coral.aoml.noaa.gov> wrote:

> Scott,
>       I'd been thinking that maybe some of your posts that I responded to
> had some exaggerations.  I actually exaggerate fairly frequently in
> conversations, because of just what you are saying, taking things to the
> the extreme or logical conclusion often illustrates the point more vividly,
> and people understand better.  In conversations, I try to always follow my
> exaggerations by saying something like "I'm exaggerating here of course,
> but exaggerating is fun and sometimes useful."  I want people to know that
> I know that I'm exaggerating, and that I don't think the exaggeration is
> literally true, it's done for didactic purposes.
>       I take the 99.9% comment in that vein.  I was going to reply that
> putting 99.9% of all your eggs in one basket and is a super risky thing to
> do.  My guess is that funding agencies realize this, so even though one
> thing may seem the most promising, they fund several of the top things, to
> hedge their bets and be sure to fund at least a few that pan out.
>       I completely agree that promising scientific ideas and leads like
> yours should be funded and pursued, and find it hard to imagine that anyone
> in their right might would not want to do that.  And encouraging young
> people to think big and think outside the box and aim high is a very good
> thing.
>        Further, I agree with the idea of "going for the gold."   To me, the
> biggest prize, the gold, is saving coral reef ecosystems.  Steve and  I
> agree, I think, that the saving coral reefs will require, necessarily,
> avoiding the worst of global warming and climate change.  We're glad to see
> you agree.  We just get distressed when people act like that's not a
> priority.
>        My point was I thought that corals could die from high temperatures
> quickly, if the temperatures are high enough, and that people who say they
> die of starvation imply that is the only way they die, and while I wouldn't
> be at all surprised if they die that way sometimes I think they can also
> die quickly from it just being way too hot.
>        I interpret Ross Jones' papers as showing that and going beyond what
> I was guessing, to show that bleaching and coral mortality are two
> separate, and separable things.  If they get too hot they can die quickly
> after bleaching or even before bleaching.  Bleaching is not necessary to
> produce mortality from high temperatures.  And, you can produce bleaching
> that doesn't lead to coral mortality.  They are two different processes.
>       For the big picture, the gold prize of saving the world's coral reef
> ecosystems, I think coral mortality is vastly more important than
> bleaching.  Bleached corals don't have to die, if it isn't too hot they can
> survive, recover and go on to reproduce a few years later.  Bleaching is a
> warning sign that corals are stressed and close to the mortality
> threshold.  But when coral colonies die, for them the game is up and death
> is permanent, and for the coral reef ecosystem, that takes a lot longer to
> recover from, and recovery is more uncertain, since there might be a phase
> shift away from coral to something like algae, and the system could get
> stuck in a non-coral state and not return in the foreseeable future.  But
> I'm not saying that bleaching is harmless or we should it ignore it, quite
> the contrary.
>        There are people who say we are going to have to learn to live with
> changed ecosystems.  That may be true.  But I don't think living with algae
> beds or coral rubble fields that replace coral reef ecosystems is going to
> be any picnic.  Perhaps my biggest worry is that as far as I know,
> macroalgae beds don't produce very many fish.  And my observations suggest
> that coral rubble beds produce precious few fish.  There are several
> hundred million people in low-income countries, living along reef
> shorelines that absolutely depend on coral reef fish for food and
> survival.  I've seen estimates in the 200-500 million people range, if I
> remember.  Those people will be in dire straights if most of the corals get
> killed by global warming.
>      By the way, I have yet to see an explanation of how selectively
> breeding temperature resistant corals, whether in captivity or ocean coral
> farms, is going to save the world's corals.  There is a no so small matter
> of how do you scale up from a few hundreds or thousands of colonies to not
> just billions, probably way more than trillions of colonies on reefs.  Same
> applies to anyone who figures out a way to get corals not to bleach.  That
> doesn't mean we should abandon those projects.  But we need to be realistic
> and not put all our eggs into that basket, because the chances we'll find
> some miraculous way of planting out 10 to the 15th power corals on the vast
> area of the world's coral reefs isn't very high.  It is, actually, treating
> the symptoms, not the cause of the disease.  "An ounce of prevention is
> worth a pound of cure."  If we want to solve the problem, we HAVE to
> minimize global warming.  No other way around it.  There was a Palumbi
> group article that found that if we warmed on one of the lower pathways,
> corals could adapt, but on the higher or even medium pathways, they can't.
> There is a physiological limit to how far and fast corals can evolve
> temperature tolerance.  Once the oceans reach that limit, from there on,
> selection and assisted evolution and natural evolution will not save
> corals.  Will not, and then if we put all our eggs in that basket, we lose
> the game, we lose the coral reef ecocsystems, lose the prize, the gold,
> lose completely and utterly and 10's of millions of human lives will be at
> risk as a result.
>       We HAVE to get global warming under control, not just for reefs, but
> to keep parts of the world at habitable temperatures for humans.  It is in
> our own best self interest.
>        Cheers,  Doug
> On Mon, Mar 30, 2020 at 3:13 AM Scott Wooldridge via Coral-List <
> coral-list at coral.aoml.noaa.gov> wrote:
> > Hi Steve,
> >
> >
> >
> > As you may have picked up, I was extending my comments to their
> > thought-provoking extremes. Obviously, many scientists are doing
> innovative
> > work on trying to better understand the inner working of the coral
> > bleaching process. Indeed, I read a great summary report in a recent
> issue
> > of PNAS, which is well worth a read.
> >
> >
> >
> > https://www.pnas.org/content/117/5/2232.short
> >
> >
> >
> > You are also correct that many scientists, managers and policy makers
> have
> > been striving to improve reef water quality as an important conservation
> > measure.
> >
> >
> >
> > What I will say, however, is that what I am advocating is not the idea
> that
> > poor water quality is just one (of many) additive stresses that impact on
> > coral reefs, i.e. a contributing straw that helps breaks the camel’s
> back.
> > Instead, I envisage inorganic nutrient enrichment as an intrinsic,
> > co-determining driver of thermal coral bleaching. That is, excess
> nutrient
> > enrichment increases the likelihood of coral bleaching (per unit thermal
> > anomaly).  To understand this better, and how it interacts with our
> efforts
> > to reduce future rates of global warming, check out:
> >
> >
> >
> >
> >
> https://www.researchgate.net/publication/235762816_Safeguarding_coastal_coral_communities_on_the_central_Great_Barrier_Reef_Australia_against_climate_change_Realizable_local_and_global_actions
> >
> > Abstract
> >
> > The threats of wide-scale coral bleaching and reef demise associated with
> > anthropogenic (global) climate change are widely known. Less well
> > considered is the contributing role of conditions local to the reef, in
> > particular reef water quality, in co-determining the physiological
> > tolerance of corals to increasing sea temperatures and declining pH.
> Here,
> > the modelled benefit of reduced exposure to dissolved inorganic nitrogen
> > (DIN) in terrestrial runoff, which raises the thermal tolerance of
> coastal
> > coral communities on the central Great Barrier Reef (Australia), is
> > considered alongside alternative future warming scenarios. The
> simulations
> > highlight that an 80% reduction in DIN ‘buys’ an additional ~50–60 years
> of
> > reef-building capacity for No Mitigation (‘business-as-usual’) bleaching
> > projections. Moreover, the integrated management benefits provided by:
> (i)
> > local reductions of ~50% in DIN contained in river loads, and (ii) global
> > stabilisation of atmospheric CO2 below 450 ppm can help ensure the
> > persistence of hard-coral-dominated reefscapes beyond 2100. The
> simulations
> > reinforce the message that beyond the global imperative to mitigate
> future
> > atmospheric CO2 emissions there still remains the need for effective
> local
> > management actions that enhance the resistance and resilience of coral
> reef
> > communities to the impacts of climate change.
> >
> >
> >
> > I hope this clears up some misconceptions, and assures people that beyond
> > water quality improvements I DO also advocate strongly of the importance
> of
> > reducing our carbon footprints.
> >
> >
> >
> > But the central tenet of my previous post remains. We need to keep
> pressing
> > for a more comprehensive understanding of the coral bleaching mechanism.
> It
> > is not perfectly understood. Lots still remains to be discovered. And we
> > should be excited by the challenges that presents, and the hope that
> > remains for finding solutions to help save coral reefs from extinction.
> >
> >
> > For your consideration,
> >
> >
> >
> > Scott
> >
> >
> > >
> > > Message: 3
> > > Date: Wed, 25 Mar 2020 16:26:46 -0400
> > > From: sealab at earthlink.net
> > > To: Scott Wooldridge via Coral-List <coral-list at coral.aoml.noaa.gov>
> > > Cc: coral list <coral-list at coral.aoml.noaa.gov>
> > > Subject: Re: [Coral-List] So you think you understand coral bleaching?
> > > Message-ID: <31dd1334-25d8-4ffa-9193-bcdf8e2774c4 at Steves-iPad>
> > > Content-Type: text/plain; charset="utf-8"
> > >
> > >
> > >
> > > Hi Scott,
> > >
> > > Your ideas certainly raise some interesting points. I agree that the
> reef
> > > science community here can sometimes get bogged down discussing how to
> > > minimize our carbon footprints, but I was struck most by your assertion
> > > that instead, finding a CURE for bleaching should consume ?99.9% of the
> > > best thinking time? of coral reef scientists. As I view it, coral
> > > scientists are in no way resigned to the belief that reducing global
> > carbon
> > > emissions is the ?sole solution?. If anything, there are already great
> > > efforts being made to divert attention away from the need to address
> > > climate change and towards an efficacy favoring restoration involving
> > some
> > > form of enhanced resistance. These projects may not be based on the
> > > END of the bleaching response as you described, but they are focused on
> > > similar goals. In addition, if the favorable symbiotic conditions you
> > seek
> > > are dependent on ?ensuring a severe limitation of the seawater supply
> of
> > > nutrients? - haven?t we been striving for this all along?
> > >  It sounds to me like the venerable call for improvements in water
> > quality
> > > that many have been advocating for years. Let?s just imagine that the
> > > supply of nutrients was miraculously brought under control and water
> > > quality was restored. With that elusive goal achieved, wouldn?t it be
> > > better to work to reduce carbon emissions and then let nature take its
> > > course? Why would we want to turn our backs on trying to solve the
> > > existential problem that is climate change with all of its implications
> > for
> > > both marine and terrestrial ecosystems in search of a highly improbable
> > > ?cure? or coral bleaching? What could be better than envisioning a
> > scenario
> > > whereby we effectively address climate change AND restore water quality
> > > thereby reducing widespread bleaching and outbreaks of coral diseases
> all
> > > in one fell swoop? That?s what I would call going for the gold! If our
> > > current crisis with COVID-19 teaches us anything, it should serve as
> > > testimony to the connectivity and fragility of life on this planet
> > >  . A lesson that we would all do well to apply to climate change and
> the
> > > many challenges it presents to us all.
> > >
> > > Regards,
> > >
> > > Steve
> > >
> > > Sent from EarthLink Mobile mail
> > >
> > > nd of Coral-List Digest, Vol 139, Issue 19
> > > *******************************************
> > _______________________________________________
> > Coral-List mailing list
> > Coral-List at coral.aoml.noaa.gov
> > https://coral.aoml.noaa.gov/mailman/listinfo/coral-list
> --
> Douglas Fenner
> Lynker Technologies, LLC, Contractor
> NOAA Fisheries Service
> Pacific Islands Regional Office
> Honolulu
> and:
> Consultant
> PO Box 7390
> Pago Pago, American Samoa 96799  USA
> "Already, more people die  <http://www.nws.noaa.gov/om/hazstats.shtml>from
> heat-related causes in the U.S. than from all other extreme weather
> events."
> https://www.npr.org/2018/07/09/624643780/phoenix-tries-to-reverse-its-silent-storm-of-heat-deaths
> Even 50-year old climate models correctly predicted global warmng
> https://www.sciencemag.org/news/2019/12/even-50-year-old-climate-models-correctly-predicted-global-warming?utm_campaign=news_weekly_2019-12-06&et_rid=17045989&et_cid=3113276
> "Global warming is manifestly the foremost current threat to coral reefs,
> and must be addressed by the global community if reefs as we know them will
> have any chance to persist."  Williams et al, 2019, Frontiers in Marine
> Science
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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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