[Coral-List] Previous 'deaths' of the Great Barrier Reef help explain its current 'death'

[Scott Wooldridge]

Dear CoralListers,


Just drawing peoples attention to the importance of the recent Nature
Geoscience manuscript of Webster et al. (2018) for understanding why the
Great Barrier Reef, and indeed other reefs around the globe are “the living
dead”. Title: Response of the Great Barrier Reef to sea-level and
environmental changes over the past 30,000 years.

https://www.nature.com/articles/s41561-018-0127-3


The mass mortality event of most relevance is that which occurred around 10
000 years ago on the GBR - for which the authors explain occurred due to an
influx of terrestrial sediment and nutrients as sea level flooded onto the
continental shelf.


I have previously predicted the occurrence of this event horizon prior to
this data becoming available - based entirely on a cellular energetics
model of the coral-algae symbiosis, and how the combination of pCO2 >260ppm
and nutrient enrichment are incongruous with the persistence of the
symbiosis.


See:


https://www.researchgate.net/publication/317100418_Instability_and_breakdown_of_the_coral-algae_symbiosis_upon_exceedence_of_the_interglacial_pCO2_threshold_260_ppmv_the_''missing''_Earth-System_feedback_mechanism


This same event horizon is seen all around the globe (with some minor
~1-2Kyr time differences) for when the nutrient enrichment occurs (e.g.
11.5kyr BP for the Caribbean). See above manuscript for details.


The importance of this???

Lots – and it is well worth stopping your research projects for a week and
just contemplating. It may save you and your stakeholders a lot of wasted
time and resources.


In particular, it explains that our current pursuit for allusive pink
underwater unicorns (opps I mean Super Corals) that can handle modern high
pCO2 and temperatures in nutrient replete waters is just a figment of our
desires and imagination. It is simply not possible that they can
existent/persist, even at temperatures and pCO2 levels lower than today
(e.g. as occurred 10-11.5kyr BP). Such a statement requires that you
understand the biophysics of the above manuscript, in particular the
thresholds outlined in Fig. 7.


Also - it explains why coral restoration projects are doomed to failure,
unless seawater nutrients are extremely oligotrophic, i.e. zooxanthellae
levels for branching and plating corals <1.2 x10^6 cells per cm2 of host
surface tissue.


As always, feel free to criticise – I am old enough and ugly enough to
handle it. It is unlikely that I will respond. Make your case to the young
emerging experimental scientist – not me. Tell them what they should be
expecting to see/discover if Super Corals or coral restoration projects are
to be the saviours of the near approaching death of the world's coral
reefs.


Scott


https://www.researchgate.net/profile/Scott_Wooldridge