[Coral-List] Decline of Red Sea coral reefs

Tue Mar 12 11:15:49 UTC 2024

Dear Joe, Austin, et al.

Apologies for the slow response, but a comment, for info, about the 
report of bleaching in the Saudi Red Sea. One needs to distinguish 
between different parts of the Red Sea in discussing likelihood of 
bleaching.

There is a very large temperature gradient over 2000 km from north to 
south. The northern end is not even in the tropics and rarely 
experiences temperatures more than about 27DegC. Indeed temperature 
today in Aqaba is 21.3. This is the area highlighted as unlikely to 
bleach in the immediate future.

Parts of the southern Red Sea in contrast regularly experienced near 
bleaching type temperatures (> 30degC) during the summer even prior to 
recent climate change, and I occasionally experienced >33degC even in 
the 1970s.

cheers, Rupert

Rupert Ormond
Co-Director, Marine Conservation International
Hon. Professor, Centre for Marine Biodiversity & Biotechnology, 
Heriot-Watt University, Edinburgh
Editor REEF ENCOUNTER (news journal of the International Coral Reef Society)

On 26/02/2024 19:14, Austin Bowden-Kerby via Coral-List wrote:
> Dear Joseph,
>
> Based on what I see here in the South Pacific, I agree 100% with your
> conclusions; that even the coral reefs we expected to be doing the very
> best in the face of climate change, are now collapsing due to warming
> seas.  There is indeed very little runoff and low fishing pressure on these
> Red Sea Reefs, especially as compared to most Caribbean and IndoPacific
> reefs.  Certainly oil spills and pollution related to shipping have been
> chronic and not something new, and mostly minor and not a forcing factor,
> so they can not be blamed on the sudden and recent demise of these reefs.
>
> The Chagos, Phoenix and Line Islands are also in this category of extreme
> impacts from bleaching and virtually none from pollution or overfishing.
> While many of these degraded reefs of pristine waters continue to be
> dominated by dead coral rock, a few reports have come out on these reefs
> loudly celebrating "recovery" of these systems, however these reports have
> glossed over the fact that although coral cover has indeed recovered, coral
> biodiversity has not, as the reefs have become dominated by one or very few
> species, with multiple local extinctions or near extinctions of Acropora
> and other species.
>
> With the global thermal anomaly of +0.7C or which occurred in 2023
> continuing, we have now gone over the edge.
> https://climatereanalyzer.org/clim/sst_daily/    Very quickly now we will
> see that bleaching and mass coral death due to marine heat waves will begin
> to outstrip all other factors in coral reef decline.  With mass coral
> die-offs, all progress with MPAs and pollution control are swept away.  But
> as long as there are some coral larvae, the consolation is that these
> better managed reefs might recover more quickly?
>
> We have entered a new reality that most of us will have a hard time
> embracing.  Most coral reefs of the Caribbean experienced 20 Degree Heating
> Weeks and some even went to 25 DHW. last summer.  And we are now entering a
> springtime with record heat levels in the region, with Tobago predicted to
> be at bleaching warning stage in 9-12 weeks!
> https://coralreefwatch.noaa.gov/product/vs/gauges/leeward_caribbean.php
>   So unless a series of early hurricanes forms and continues to form in the
> tropical Atlantic, it looks like this coming summer has the potential to be
> as bad or worse than last summer.  So are you ready?
>
> I strongly believe that it is time that we embrace our new reality, realize
> that the situation will worsen very quickly now, and that if we do not
> begin active coral-focused measures to keep coral species alive and in
> genetically diverse condition, that we are going to lose them, reef by
> reef, nation by nation.  I know it is difficult to imagine our reefs
> experiencing 25-27 DHW, but that is now an actual danger!  It is time to
> face this new reality and to develop plans and actions to keep
> corals alive, species by species, and in the ocean.  I have some ideas on
> how to do this:  In 2016, I began working with the coral reefs of
> Kiritimati Atoll (Christmas Atoll), on the equator, just south of Hawaii.
> Kiritimati is the clear leader globally for being the most severely
> impacted of all coral reefs by bleaching, with 27 DHW experienced in
> 2015-16.   After seeing the severe impacts and local extinctions of so many
> coral species, my question was this: what could we have done to prevent the
> coral extinctions that occurred?   I came up with some answers, and I
> launched these ideas and strategies as "Reefs of Hope", with pilot sites in
> six Pacific Island nations.  The good news is that Reefs of Hope has just
> this month been endorsed by UNESCO as an Ocean Decade Action:
> https://oceandecade.org/actions/reefs-of-hope/    I think this makes Reefs
> of Hope the first UN-endorsed corla-focused climate change adaptation
> strategy for coral reefs!
>
> An underlying assumption of the Reefs of Hope model is that even during the
> most severe of marine heat waves the open ocean generally does not get
> above 31-32C, 33C in the extreme.  We also assume that ocean facing reefs
> are generally cooler than nearshore reefs.  Nearshore coral populations
> located on hot reef flats and in closed lagoons can easily take 31-33C and
> above without bleaching, however during severe marine heat waves these hot
> areas can really cook, reaching temperatures similar to the 38.4C recorded
> in Florida last summer.  So with mass bleaching we are also losing our
> greatest genetic treasures: the coral hosts, the symbionts, and the
> microbiomes present.  However, these same corals will do just fine if we
> can get them into cooler more oceanic waters beforehand.  So one of our
> Reefs of Hope strategies is hot to cooler translocation of corals at local
> scale in order to prevent their death during increasingly severe marine
> heat waves.   If we are too late, another method we use is to collect the
> few unbleached corals after mass bleaching events (when the waters begin to
> cool), to protect them from predators, using these corals to build the gene
> bank nurseries, later trimmed to create "nucleation patches" on the reef to
> reboot natural adaptation and recovery processes, as well as to restore
> effective sexual reproduction to declining coral species.
>
> I am not saying that we have all the answers, and we are still learning,
> but the answers we urgently need will only come with concerted actions and
> the sharing of knowledge.  It is time to work together and to develop
> regional and global strategies and programs.  Every man for himself is not
> a good way to win a war.
>
> Regards,
>
> Austin
>
> Austin Bowden-Kerby, PhD
> Corals for Conservation
> P.O. Box 4649 Samabula, Fiji Islands
> https://www.corals4conservation.org
> Publication on C4C's coral-focused climate change adaptation strategies:
> https://www.mdpi.com/2673-1924/4/1/2/pdf
> Film on our "Reefs of Hope" coral restoration for climate change adaptation
> strategies:https://www.youtube.com/watch?v=BG0lqKciXAA
> https://www.globalgiving.org/projects/emergency-response-to-massive-coral-bleaching/
> <https://www.globalgiving.org/projects/emergency-response-to-massive-coral-bleaching/>
>
>
>
> On Sat, Feb 24, 2024 at 2:50 AM Pawlik, Joseph via Coral-List <
> coral-list at coral.aoml.noaa.gov> wrote:
>
>> Greetings, list,
>>
>> More sad news about which you may not be aware: Red Sea coral reefs are
>> rapidly losing coral cover from south to north because of summer high
>> temperature events and unprecedented storms. Some of us had hoped that
>> these reefs were resistant to climate change impacts, but evidently not.
>>
>> Here is a video that shows the dramatic change in coral cover between 2019
>> and 2023 (effects of 5 summers) on reefs south of Marsa Alam, Egypt.
>>
>> https://youtu.be/_-v7s4eBok0
>>
>> Note the recently dead and toppled Porites lutea - many of these heads are
>> hundreds, if not thousands of years old.
>> The video also shows dead reefs south of Al Lith on the Saudi Arabian side
>> of the Red Sea - this is further south of the Egyptian reefs in the first
>> part of the video, and these reefs died before 2017.
>>
>> Important relative to recent discussions on this list is that these tragic
>> losses are due entirely to high temperature events - these reefs are not
>> impacted by human settlements or sources of pollution, nor is there
>> evidence of disease events.
>>
>> Regards,
>>
>> Joe
>>
>> **************************************************************
>>
>> Joseph R. Pawlik
>>
>> Frank Hawkins Kenan Distinguished Professor of Marine Biology
>>
>> Dept. of Biology and Marine Biology
>>
>> UNCW Center for Marine Science
>>
>> 5600 Marvin K Moss Lane
>>
>> Wilmington, NC  28409
>>
>> Office:(910)962-2377; Cell:(910)232-3579
>>
>> Website:http://people.uncw.edu/pawlikj/index.html
>>
>> PDFs:http://people.uncw.edu/pawlikj/pubs2.html
>>
>> Video Channel:https://www.youtube.com/user/skndiver011
>>
>> **************************************************************
>>
>>
>>
>>
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