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

Scott Wooldridge swooldri23 at gmail.com
Tue Mar 24 10:17:11 UTC 2020


Dear Coral Listers,



I think it is fine that the reef science community discusses strategies
that can help formulate new ways of doing (and reporting) our science that
can help minimize our carbon footprint. But can I suggest that we owe the
global public and the coral ecosystems themselves so much more than this.



Like those scientists tasked with finding a vaccine for COVID-19, we need
to keep challenging ourselves to find the CURE for coral bleaching. This
must consume 99.9% of the best thinking time of coral reef scientists. And
before we resign ourselves to believing that reducing global carbon
emissions (and by inference future sea temperatures) is the sole solution
we can offer the global public, I believe we need to double down on our
efforts to understanding the suite of cellular processes that initiate
coral bleaching, especially those at the FRONT END of the bleaching
response.



By FRONT END I mean those processes that happen in the days-weeks before we
see any visual sign of bleaching (i.e. symbiosis breakdown). They are
subtle, not well studied, and not well understood. But when you start to
investigate them more deeply, you quickly realize that the conceptual coral
bleaching model adopted by most-all coral reef scientists is WRONG; which
at its crudest, explains coral bleaching in terms of corals BOILING TO
DEATH in hot water.



The issue I specifically draw your attention to in this post, is the
little-known FACT that the endosymbiont population increases its size and
growth rate (as measured by cellular division rate) in the days and weeks
of warming leading up to the visual coral bleaching response.  THEREFORE,
immediately before the break down of the symbiosis, the endosymbionts are
by our best measures very happy, and by adding some anthropomorphism -
think that the symbiotic lifestyle cannot be much better.



Don’t believe this?  Don’t take my word for it. It has been very well
reported by others, most recently;



https://www.researchgate.net/publication/331593854_Effects_of_increased_heat_on_fluorescence_and_dinoflagellate_density_in_the_captive_coral_Anthelia_sp




And obviously, given my intent to get people thinking about the science of
the response, I have already had my say on this issue.


https://www.researchgate.net/publication/307695433_Breakdown_of_the_coral-algae_symbiosis_Towards_formalizing_a_linkage_between_warm-water_bleaching_thresholds_and_the_growth_rate_of_the_intracellular_zooxanthellae?_sg=-2o85tlB6whC-hSPB0t8oWFed2eECtwPxvsoVRgGKUmzu6k0TIDq5aSV6BwcOhlLqeiGGYr3KAwOMLqI2UkuYtNLnddwaWcl1ReDnhNh.pvBbZTSCSahzvcVu-JkqhLKf-zq1EbYJ6GquHXoR2Nfs2G8--J5_4bxKPwNXk0lfNXJmGnuvk3srT7GzoZSkmQ



https://www.researchgate.net/publication/44644540_Is_the_coral-algae_symbiosis_really_'mutually_beneficial'_for_the_partners?_sg=j-rvYFlYazoFU-eah3oORE-zhln-XE-Rt9sIsBFdHrjKHFWO3E1jvDuSBJmwoJ97CP1_RYFtuY-gXbicnyXyRuLK-0gAgwvn2XMNqukP.Mdg_vAKy_Zgedumry2ZUKz9kDoEj6KH_K84VDQ57AebVQnp8oLXLx95adt-cwLzuRjJ2I-j5St_pcMDr-2jtEA




All these articles ULTIMATELY explain coral bleaching in terms of a loss of
host control of the demographic parameters of its endosymbiont population.
This is very far from the CORALS BOILING IN HOT WATER conceptual model. And
that is good news!! Since it provides hope, that if we can limit the
thermo-kinetic growth potential of the endosymbionts, whilst simultaneously
retaining their capacity to release fixed carbon, we may be well on the way
to understanding what constitutes a BLEACHING RESISTANT coral. Much more
testing needs to be done on this issue. For example, can this favorable
symbiotic condition be achieved by ensuring a severe limitation of the
seawater supply of nutrients, such that the symbiont doesn’t have access to
the prerequisite nitrogenous material needed for cellular division, even
during thermo-kinetic events that promote increased division? Or, do we
need to look/find/evolve a new type/species of endosymbiont, most likely
one with a bigger cellular diameter, that will have a slower thermo-kinetic
division rate?



There are so many questions. Still unknown. Still unconsidered. Still
untested.



My challenge, especially to all the fresh thinking young scientists out
there, is to keep an open mind. Keep striving for the CURE. Never let
yourself be convinced that we already know all the necessary science to
answer this. WE DON’T and we are so very very far from it….



And finally, for a bit of comic relief as well as encouragement I am
forever drawn to the excited words of an old Australian swim coach, who
famously stated STUFF THE SILVER, WE CAME FOR THE GOLD. For those old
enough to remember, he orchestrated a brilliant tactical race for his
swimmer to beat the best simmers in the world at the 1988 Olympics. The
SILVER in coral bleaching research is to be content to quibble about the
relative merits of ways to reduce our global carbon footprint. We need to
refocus, go back to the beginning and keep searching for a CURE. Or in the
words of the excited swim coach STUFF THE SILVER, GO FOR GOLD.



https://www.youtube.com/watch?v=zgGr-quFf2k



For your consideration,


Scott Wooldridge


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