[Coral-List] amazing recovery of corals in the Southern Line Islands after bleaching mortality

Fri Nov 4 07:03:01 UTC 2022

Austin,
     I think we as scientists have to tell the story, and the whole story,
about reality.  Whether that story is good, bad, or ugly. No sugar
coating.  I post these things so people are aware of them, usually without
commenting on the article.  So I post it whether it seems good or bad.  But
then I hope people will respond, and I particularly appreciate when people
add to the story and point out aspects that aren't included in the story,
like what you've done this time.  So thank you, we all can learn.
      Perhaps this story is one of a glass half full but also half empty.
Myself, if I saw a reef that had almost all of its coral killed, to see
that coral cover had recovered so much, that would be a huge relief.
That's a lot better than if it remained dead for 40+ years, like in
Discovery Bay, Jamaica, isn't it??  I agree that it is a phase shift.  When
phase shifts on coral reefs were first reported, they were the phase shifts
in the Caribbean from coral dominated to macroalgae dominated.  Many of us,
myself included, thought that phase shifts were from coral to macroalgae.
Turns out that shifts to macroalgae domination are the exception, not the
rule, as demonstrated in the paper by Bruno et al. (2009).  Now, as your
references document, there is increasing evidence of reefs that have had
their corals hit hard, which recover much of their coral cover, but with a
different coral community.
      Personally, if I had a favorite reef and over 90% of its corals were
killed by a heat wave from climate change or crown of thorns, or a cyclone,
and its coral cover recovered, I'd be delighted the coral cover returned
even if it was a different coral community.  For some time, people have
been pointing out that coral cover isn't everything, and they are right,
you are right.  Just because the coral community is different now, does not
mean that it will remain so forever.  There will surely be more mass coral
mortality events, and maybe next time the coral won't recover and we'll be
wishing it had, even if it was changed.  Or maybe, some of the new coral
species will be able to withstand even higher temperatures, or not.  We may
be entering uncharted waters.
       I'm not claiming that phase shifts to different coral communities
are nothing.  Clearly, this is important.  If we had a choice, we wouldn't
be choosing to have these phase shifts happen.  Interestingly, they aren't
all changing to the same coral species.
       Using the word "extinction" without qualifying it, could lead to
some people taking it to mean things for which there isn't hard evidence.
In this story (which is not a peer-reviewed published scientific paper), it
is obvious that some species had drastic local population reductions from
the heat wave bleaching.  There are a variety of different types of
extinction that can be distinguished.  Local extinction, commercial
extinction, functional extinction, and global extinction being some of
them.  None of these reports would imply global extinction of any species.
These are tiny, isolated islands and most corals have gigantic species
ranges, at least the way coral species are presently defined and recorded.
The article doesn't even claim any local extinctions, though they could
only find one colony of Pocillopora for one island.  It is very hard to get
definitive evidence of extinction, because it is essentially the null
hypothesis, which can't be proven.  And in practical terms, even on a small
reef, every square inch can't be searched, usually only a tiny fraction of
the area can be searched.  The species we think is extinct could be in the
area we haven't searched, stranger things have happened.  Obviously, the
drastic reductions in some species reported in this article would be
functional extinctions.
      Anyhow, the word "extinction" is often not used with qualifiers, and
without qualifiers often used to indicate global extinction.  And I see no
evidence in this article of any global extinctions.  No evidence does not
mean it didn't occur, it just means no evidence to support the idea.  May
appear in the future, who knows.
       I think you have a good and valid point, that just because coral
cover returned, doesn't mean that the coral community didn't undergo a
phase shift, and such coral community phase shifts are now being found to
be far more common than we knew.  And I would agree that community phase
shifts may be a threat.  Not only has the coral community had a phase
shift, but it sounds like the new community has a lower diversity.  It will
be interesting to see what the reduction in diversity is.  It may not be in
the form of some species that were present no longer being present, it may
be that it is in the form of formerly common species becoming rare, while
one or a few become common or even dominant.
         Cheers,  Doug

Bruno, J. F., Sweatman, H., Precht, W. F., Selig, E. R., and Schutte, V. G.
W. 2009.

            Assessing evidence of phase shifts from coral to macroalgal
dominance on coral

            reefs. *Ecology* 90, 1478–1484.

On Tue, Nov 1, 2022 at 10:52 AM Austin Bowden-Kerby <abowdenkerby at gmail.com>
wrote:

> Thanks Doug,
>
> Yes, this sounds encouraging- on the surface, and the photos are
> beautiful!   However if you look more deeply, it is a lot less hopeful.
> What this represents is yet another case of near total phase shift in the
> coral population, and the local extinction of a whole list of species.  The
> actual reality is this: due mass bleaching, the coral population of the
> Southern Line Islands has gone from a diverse population dominated by
> Pocillopora and Acropora, to one dominated by a single species of
> Montipora.
>
> A similar phase shift has happened in Tarawa, in the Gilbert chain, due to
> bleaching, with the end state being a single species: Porites rus (Cannon
> et al, 2021).  In Kiritimati Atoll, the mass bleaching resulted in the
> local extinction of many Acropora species and a big reduction in
> Pocillopora, leaving behind only remnants of massive Porites and massive
> Pavona, (Bowden-Kerby et al, 2021).  In Moorea, the phase shift has gone
> from Acropora dominated to Pocillopora dominated (Edmunds, 2018; Carlot et
> al, 2020), related to bleaching and COTS predation.  This phase shift has
> been well documented for the Red sea as well (Riegl et al, 2013), with a
> shift away from Acropora towards Pocillopora and Porites, attributed to a
> combination of mass bleaching and COTS predation.
>
> These phase shifts transform the habitat characteristics of the reef, away
> from what the original species.  The resulting reefs provide poor habitat
> for juvenile fish and plankton-feeding fish like Chromis, which require
> branching coral species.  These phase shifts represent weedy and
> long-lasting coral species, which can dominate the settlement surfaces and
> prevent larval based recovery of the reef back to its original coral
> population. Few of these authors seem to understand this, and so they
> celebrate and use the word "recovery" in their titles.  However, these
> phase shifts represent degraded alternate steady-state conditions.
> Unfortunately GCRMN will support these authors, as it only looks at coral
> cover, not genera, and so it will not pick up or highlight these phase
> shifts and species extinctions either.
>
> I have two recommendations related to this information:
> 1. GCRMN needs to be updated to include coral genera!  Seriously- how can
> GCRMN be missing so much of the plot?
> 2. The authors of these sorts of "recovery" studies need to present phase
> shifts with less glee and celebration. A more detached and honest view will
> present the tragedy that has happened.  Yes, the alternative state
> sometimes is rather glorious and beautiful, appearing to be an improvement
> over barren rock, but the fact is that these phase shifts represent local
> extinction events for coral species essential to ecosystem function,
> fisheries, and coral reef geology.  And these phase shifts might also
> prevent the return to the original populations, cementing in the extinction
> event.
>
> We can not allow increasing coral cover to trick us into thinking that an
> actual recovery has happened.
> If we do, we risk being seduced by the enemy and missing the evil plot
> that climate change is weaving, tricking us into inaction!
>
> I think that there is enough evidence to come to the conclusion that coral
> reefs are dying out as a series of phase shifts.  Only this recognition
> will help us refrain from celebrating the shift, and to stop labeling it
> recovery.
> Only by understanding these basic processes occurring on coral reefs under
> increasing stress, can we then begin saving the reefs.
>
> What happens when the next mass bleaching event or perhaps predators or
> disease kills off much of the Montipora of the Southern Line Islands?  Will
> this unstick the alternative steady state and allow recovery? Not unless
> there is a source of coral larvae from the original, now missing coral
> species.  How does a high coral cover single-species dominated reef get
> restored to its original highly diverse state?  On Kiritimati, after the
> mass coral die-off in 2015-16, and while coral cover was still under 5% for
> the two remaining massive species, we turned our focus to finding the few
> remnant survivors of formerly dominant Acropora and Pocillopora coral
> species, and growing them within a recovery nursery.  The focus was on
> restoring sexual process to the corals, by collecting the widely spaced and
> ecologically extinct survivors, growing them, and getting them back
> together.  While several formerly abundant Acropora coral species could not
> be found, we have succeeded in restoring reproduction to patches of seven
> Acropora and two Pocillopora species.
>
> A 22 minute presentation on our 'Reefs of Hope' strategies is here
> https://youtu.be/arkeSGXfKMk    And to the list: we welcome self-funded
> research partners and graduate students in our sites.
>
> Vinaka, and kind regards to all,
>
> Austin
>
> Cannon SE, Aram E, Beiateuea T, Kiareti A, Peter M, Donner SD (2021) Coral
> reefs in the Gilbert Islands of Kiribati: Resistance, resilience, and
> recovery after more than a decade of multiple stressors. PLoS ONE 16(8):
> e0255304. https://doi. org/10.1371/journal.pone.0255304
>
> Edmunds, P.J.  Implications of high rates of sexual recruitment in driving
> rapid reef recovery in Mo’orea, French Polynesia. 2018.  Nature: Scientific
> Reports.  8:16615 doi:10.1038/s41598-018-34686-z
>
>
> Carlot J., Rove`re A., Casella E., Harris D., Grellet-Mun C., Chancerelle
> Y., Dormy E., Hedouin L., Parravicini V.  2020. Community composition
> predicts photogrammetry-based structural complexity on coral reefs. Coral
> Reefs. doi: 10.1007/s00338-020-01916-8
>
>
> Riegl B., Berumen M., Bruckner A. 2013.  Coral population trajectories,
> increased disturbance and management intervention: a sensitivity analysis.
> Ecology and Evolution 3(4): 1050–1064
>
> doi: 10.1002/ece3.519
>
>
> Bowden-Kerby, A., Romero, L., and Kirata T. 2021. Chapter 17: Line Islands
> Case Study. In: Active Coral Restoration: Techniques for a changing
> planet, David Vaughn, Editor. 610pp.
>
>
>
> Austin Bowden-Kerby, PhD
> Corals for Conservation
> P.O. Box 4649 Samabula, Fiji Islands
>
>
> https://www.globalgiving.org/projects/emergency-response-to-massive-coral-bleaching/
> <https://www.globalgiving.org/projects/emergency-response-to-massive-coral-bleaching/>
>
>
>
>
>
>
>
>
> On Wed, Nov 2, 2022 at 6:01 AM Douglas Fenner via Coral-List <
> coral-list at coral.aoml.noaa.gov> wrote:
>
>> Once devastated, these Pacific reefs have seen an amazing rebirth
>>
>>
>> https://www.nationalgeographic.com/magazine/article/once-devastated-these-pacific-reefs-have-seen-an-amazing-rebirth-feature
>>
>> Cheers, Doug
>>
>> --
>> Douglas Fenner
>> Lynker Technologies, LLC, Contractor
>> NOAA Fisheries Service
>> Pacific Islands Regional Office
>> Honolulu
>> and:
>> Coral Reef Consulting
>> PO Box 997390
>> Pago Pago, American Samoa 96799-6298  USA
>>
>> Switching to renewable energy could save trillions-up to $12 TRILLION by
>> 2050.
>> https://www.bbc.com/news/science-environment-62892013
>>
>> 1 in 6 deaths worldwide can be attributed to pollution, new review shows
>>
>> https://www.msn.com/en-us/health/medical/1-in-6-deaths-worldwide-can-be-attributed-to-pollution-new-review-shows/ar-AAXozQh
>>
>> UN: World on fast track to disaster, but we can avert it
>> https://www.youtube.com/watch?v=9xBVD8r0aHQ
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