[Coral-List] Pre-bleaching and Post-bleaching Strategies to Save Bleaching Resistant Corals

[Kuffner, Ilsa B]

Hello Austin and Coral List members,

Regarding Austin's request "please contact me if you have data, publications, or observations verifying any of the above," see this link for photographic evidence suggesting that shading corals from the visible portion of the solar-irradiance spectrum can help during a natural bleaching event. The photographs were taken during a 2004 high-temperature anomaly in Kaneohe Bay, Hawaii. The timeseries images and associated metadata are in the public domain so that they are free for anyone to access and use.

https://www.usgs.gov/media/images/coral-shading-experiment-during-a-bleaching-event

Best, Ilsa


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Ilsa B. Kuffner, Ph.D. (she/her)

U.S. Geological Survey

St. Petersburg Coastal & Marine Science Center

600 4th Street South

St. Petersburg, FL 33701



Email: ikuffner at usgs.gov<mailto:ikuffner at usgs.gov>

Tel: (727) 502-8048
Fax: (727) 502-8001
http://coastal.er.usgs.gov/crest/
https://www.usgs.gov/staff-profiles/ilsa-b-kuffner

https://scholar.google.com/citations?user=OWeHTdkAAAAJ&hl=en&oi=ao


"In order to tackle the climate crisis and strengthen our nation’s economy, we must manage our lands, waters, and resources not just across fiscal years, but across generations.” --- Deb Haaland, Secretary of Interior, March 25, 2021

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________________________________
From: Coral-List <coral-list-bounces at coral.aoml.noaa.gov> on behalf of Austin Bowden-Kerby via Coral-List <coral-list at coral.aoml.noaa.gov>
Sent: Tuesday, November 29, 2022 5:30 PM
To: coral list <coral-list at coral.aoml.noaa.gov>
Subject: [EXTERNAL] [Coral-List] Pre-bleaching and Post-bleaching Strategies to Save Bleaching Resistant Corals

Dear fellow coral listers,

Seeing what is coming in the GBR and Melanesia area, I thought others in
the region might want to know our approach to dealing with mass
bleaching, based on years of experience, observations, and simple logic.

While some may rightly ask for peer reviewed publications to verify the
efficacy of these strategies, the fact is that there are no recognized
strategies for dealing with mass coral bleaching, and so for the most part,
everyone just watches on in horror.  But this need not be so.

However, there are some things that can be done, and here are the
strategies that we use in our Fiji sites.

*Pre-bleaching Interventions*

*Rescuing bleaching-resistant corals by translocation from hot pocket reefs
to cooler water nurseries*

Corals found within ‘hot pockets’ are pre-adapted to withstand the high
temperatures of climate change, some withstand 35-37C without bleaching in
our sites. However, these corals live at the upper limits of thermal
tolerance for corals and they certainly cannot survive temperatures
approaching 40°C, which may soon occur in the shallows during the
approaching extreme bleaching event.

Our strategy identifies threatened corals found within hot pocket reefs,
and secures these corals from an approaching demise, moving samples of
these corals into nurseries located in cooler waters of appropriate
habitat. The Acropora and many other species found In the hot pocket reefs
are also found on cooler water reefs.  If we do nothing both populations
are equally in danger of dying out due to bleaching.  We need the heat
adapted individuals to survive, and they will if we can move them now.

While It is generally not advised to move corals during times of thermal
stress, when we must we simply shade them under underwater shade cloth in
the nursery, or under a wharf or floating pontoon.  A-frame nurseries are
better than rope nurseries or hanging nurseries, because the coral
fragments are secured, oriented in the proper upright position, otherwise
they hang to the side and become sunburned and badly bleached on the upward
facing surface.

If we lose the hot pocket corals on a coral reef due to inaction, it will
be a great loss for the adaptive potential of the coral reefs of that area.

*Shading to Decrease Photosynthesis During Thermal Stress *

(While this method may allow corals to survive heat stress, it may not
facilitate the long-term adaptation of corals to heat stress).

Shading is the only method know to work well to prevent bleaching during
extreme hot water events. Tarps or shade cloths or temporary rafts can be
suspended over patches of reef and the shade lowers photosynthesis and thus
helps prevents corals from producing toxic oxygen radicals.  Bamboo rafts
tied together into big squares or rectangles to support tarps might work
well for saving high-value coral colonies or coral nurseries. Corals on
ropes can easily be tied under the shade of a wharf until the bleaching
emergency abates.

*Post-Bleaching Interventions*

*Rescuing Surviving Bleaching-resistant Corals from Predators*

Based on multiple observations, after mass bleaching, when only a few
bleaching resistant corals have survived, the corals most often have a hard
time surviving due to greatly increased predation rates by coral predators
by crown of thorns starfish and Drupella snails, and even parrotfish and
butterflyfish. So within a few months, the surviving bleaching resistant
corals are mostly killed, and so post bleaching predation also kills the
adaptive potential of the coral reef.

While I am not sure what data is out there, it is only logical that
predator-to-prey ratios will become highly skewed when mass coral die-offs
happen.  Acropora corals are particularly vulnerable. And so if we want to
help the coral reefs adapt to climate change, it is vital that we collect
samples of the surviving corals as soon as possible either during or
immediately after bleaching, so that these corals can be protected and
propagated within “gene bank” nurseries, for later use in restoration and
facilitated adaptation.  An intensive coral predator control program is
also recommended post bleaching, but before the predators are eliminated,
some damage will be done, so both coral collection and predator removal
should go hand in hand where possible.  We sometimes implement a bounty on
COTS, to encourage communities to collect them.

Please contact me if you have data, publications, or observations verifying
any of the above.

If any want information on how to construct or anchor the A-frame
nurseries, we can send that. We have recently made a film showing how.  We
get four 3m x 1m frames from a single sheet of heavy welded concrete
reinforcing floor mesh, and each A-frame can hold about a hundred coral
fragments.

Most everything that we do these days in our coral work is preparation for
what is coming as the oceans warm.  So we no longer call our coral work
restoration, we call it coral-focused adaptation.  The focus throughout the
year is on finding and securing pre-adapted bleaching resistant corals,
moving them from hot to cool waters, where they can begin interacting more
directly with cool adapted coral populations, to hopefully share resistant
symbionts.  We also focus on the preservation of the resistant corals
themselves, to prevent their local extinction as the planet warms.

When a massive firestorm approaches on the horizon, planting trees for
reforestation is suspended, and the focus becomes strategies that will
enable the long-term survival of the trees and plants. Now is the time to
channel our restoration efforts into facilitating adaptation and securing
these precious pre-adapted corals.  Once we have them, restoration efforts
become adaptation.  It will be like planting fire resistant trees, of the
same original species that were fire sensitive.

Regards, and good luck in your sites,

Austin