[Coral-List] New Paper: Resilient corals in the Phoenix Islands

Mon Sep 20 16:41:21 UTC 2021

Hi Mike and Austin et al, thanks for your focus on this process of selection. What pops out is that there are two layers of selection - community selection of the most heat tolerant species, and adaptive selection for the most tolerant genotypes within species. Maybe one way forward is to talk about the impacts of both of these on reef function. 

Like others I’ve been on many heat-exposed reefs dominated by slow growing Porites and Heliopora. How well do they support reef production and growth compared to other community compositions? Likewise, how well do heat resistant Acropora fare in other measures such as disease tolerance, growth or other measures of fitness?

One way of thinking about whether community or adaptive selection are positive is whether they benefit reef and human communities compared to the alternative. I’m not sure we know this completely yet!

all the best
Steve
*******************************************
Stephen Palumbi
Jane and Marshall Steel, Jr. Professor of Marine Biology
Stanford University
Hopkins Marine Station
microdocumentaries at http://microdocs.org

On Sep 20, 2021, at 4:10 PM, Austin Bowden-Kerby via Coral-List <coral-list at coral.aoml.noaa.gov> wrote:

Dear Michael,

Thanks for your detailed and thoughtful reply.  Sorry if my letter was
unkind, your paper is indeed excellent and very useful information.  I
absolutely agree with your conclusions in the text and at the end about the
need to conserve and protect these more adapted coral populations.

I also was contacted by Nathan Cook regarding not yet published survey work
(with Adam Smith and others), that shows some good Acropora populations
surviving in the Kanton lagoon, but with very little Acropora surviving on
the reef front where the corals had not developed thermal tolerance due
to the cooler conditions.  While the continuing presence of Acropora is
reassuring, I consider that this is not only due to bleaching resistance,
it is also due to the less severe intensity of the event when compared to
the islands closer to the equator like Jarvis and Kiritimati Atoll.  If
that hot water pool had hit Kanton directly, most of these corals would
also be dead.

The reason I posted my concern was that I had just read one of the several
news stories which have been posted on social media, using your studies and
others to present an overly optimistic outlook, which I consider to be out
of touch with the wider reality.  The news reports on this work fail to
mention that the Phoenix islands were not as severely impacted by this
particular heat wave, which severely impacted Jarvis and close to 100% of
its corals were lost (0.3% cover, Brainard et al. 2018), as well as
Kiritimati Atoll, which lost 95% of its corals overall and virtually all of
its Acropora and Pocillopora corals (Bowden-Kerby, 2021). These press
reports often fail to mention that the bleaching is coming with increased
frequency and force, and that since the 2014-15-16 event, the Gilbert chain
experienced  two additional severe bleaching events in 2018-2019, and
2019-2020, and that no systematic assessment of the reefs has been done.

My biggest concern is that the Government of Kiribati, perhaps in part due
to the reporting the media has picked up from your report and others,  has
remained unaware of the seriousness of the situation.  Imagine what the
response would be if the reefs Hawaii or Fiji were killed off in a severe
mass bleaching event?  There are no eyes on Kiribati, as it has been five
years with no response.  None of the major international conservation NGOs
work in Kiribati.  But even simply following the NOAA remote sensing data
should establish that Kiribati's coral reefs are the most impacted from
bleaching temperatures of any coral reefs on earth, and that a disaster of
huge magnitude has hit beneath the water, but no one seems to have noticed-
and so there is absolutely no response!   What lessons might be learned
that are now being lost?   Kiribati is the leading edge of the predicted
planetary demise of coral reefs, and therefore the situation warrants a
proper and more intensive monitoring and assessment program.  For now, the
Phoenix Islands might be the only part of Kiribati that was at least
partially spared, but what will the coming years bring?

Again, while the evidence of thermal adaptation on Kanton is a valid reason
for some hope, it is clear from the data that the main body of the hot pool
never reached Kanton and nearby atolls.  Jarvis and Kiritimati were
immersed in the dark heart of the oceanic hot blob of 2015-16, and very few
corals of any species survived.  The coral populations of Palmyra to the
North were also on the fringe of the hot blob, and your paper reporting
corals surviving intact there has also been reported in the media as a
cause for hope.  Perhaps it is these moderately stressed coral
populations, where corals can best adapt and become more bleaching
resistant?  But the big question is whether these more adapted coral
populations will in the future be able to survive the intensity of heat
that the region is capable of generating?  There is reason to doubt that
they will, because the most resistant of the corals are located in the warm
shallows and within the warm lagoons, and it is these same lagoons and
shallows which have the potential to get so hot as to exceed all
possibilities for coral survival.

The Kiritimati mass die-off of corals has impacted me deeply, and caused me
to reexamine everything I was doing with coral restoration, and to change
my coral restoration approach.  I kicked myself, and realized: if only we
had come a few years earlier and collected samples of the bleaching
resistant corals from the lagoon, and moved them into a nursery near the
much cooler pass, or transplanted them onto the reef front directly, they
would certainly have survived.   Now I live with the realization that time
is ticking away for the remaining hot pocket reefs and thermally adapted
coral populations everywhere- including those in Kanton lagoon, are in
grave danger of dying out in the coming years.  This is why we now focus
most of our restoration efforts on moving coral samples from the hottest
parts of the lagoons and nearshore reefs into cooler waters at the passes
and eventually to the reef front, so that some of the most heat adapted
corals stand a good chance of surviving the next massive heat wave.  After
all these are for the most part the exact same species. The corals you have
recorded for Kanton and the other Phoenix Islands are precious resources
for the future.  If a program to sample multiple genotypes of these
bleaching resistant corals and to transplant them to where the water will
never reach the 35-40C conditions possible at some future date for the
lagoons, they will not only survive, but they may not even bleach at all.
The corals can then also spread their resilience.  But how long do we
have?  When can we begin?

Lastly, is my perspective on Acropora is as an old timer, living in
Micronesia as a pre-teenage and teenage boy in the 1960s, and visiting many
islands and atolls in the 1970s and 80s, my recollection is that the reef
front and lagoon populations of just about all atoll reefs are Acropora
dominated- at least they were back then. Tuvalu and Tokelau, the nearest
coral reefs, both remain Acropora dominated.  So to me it seems that Kanton
and the Phoenix islands must be atypical- already on their trajectory to
alternate steady states?  I suspect that a geological core would show
Acropora dominance up until relatively recent times.  Did a phase shift
happen when no one was watching?  On geological timescales, I don't see
much prospect for non-Acropora reefs keeping up with rising seas and/or
natural subsistence, but of course any coral at all is better than none.

Thanks for listening,

Austin

Austin Bowden-Kerby, PhD
Corals for Conservation
P.O. Box 4649 Samabula, Fiji Islands
https://www.corals4conservation.org
TEDx talk https://www.youtube.com/watch?v=7PRLJ8zDm0U
https://www.globalgiving.org/projects/emergency-response-to-massive-coral-bleaching/
<https://www.globalgiving.org/projects/emergency-response-to-massive-coral-bleaching/>

Teitei Livelihoods Centre
Km 20 Sigatoka Valley Road, Fiji Islands
(679) 938-6437
http:/www.
<http://permacultureglobal.com/projects/1759-sustainable-environmental-livelihoods-farm-Fiji>
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On Thu, Sep 16, 2021 at 7:07 PM Michael Fox via Coral-List <
coral-list at coral.aoml.noaa.gov> wrote:

> Dear Austin,
> 
> 
> Thanks for sharing your perspective. However, mid-ocean atoll systems are
> not all dominated by *Acropora* in their natural state as you are
> suggesting. Indeed, the assumption that they "should be" inevitably leads
> to incorrect interpretations of ecosystem trajectory.
> 
> 
> A history of benthic monitoring in the Phoenix Islands extending to the
> late 1960s indicates *Acropora* was not the most dominant coral in at least
> the last 60 years. Further, while we don't contest that bleaching has
> reduced *Acropora* abundance in the area, these declines are not as
> pervasive as you imply. At specific sites where we know *Acropora* to have
> been locally dominant, it is recovering, rather than disappearing. Notably,
> as of 2018 Kanton's lagoon reefs are composed primarily of table and
> staghorn *Acropora*, which have recovered from almost complete mortality in
> 2002.
> 
> 
> Kiribati is comprised of 33 islands across three unique archipelagos that
> span nearly 3.5 million square kilometers of ocean. We think it is wrong to
> assume that observations from Kiritimati over a narrow window of time can
> be generalized to the rest of the reefs in Kiribati, some of which have
> withstood and recovered from recurrent heatwaves over centuries.
> 
> 
> The impact of the 2015-16 heatwave on reefs across the Pacific basin cannot
> be overstated and is a warning of what we're facing today and in the
> future. However, as the global coral reef community works to forestall
> coral reef extinction, it is important to engage in thoughtful discussion
> based on facts and accurate natural history. If some sites on coral reefs
> are managing to keep pace with climate change, like those on Kanton Island
> in PIPA, lets pay attention, identify the mechanisms by which this
> resilience is conferred, and keep open minds. We have a lot still to learn.
> 
> 
> All the best,
> 
> Mike
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> Coral-List at coral.aoml.noaa.gov
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> 
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