[Coral-List] Addressing Post-Bleaching Predation, and Making Preparations for What Comes Next

[Austin Bowden-Kerby]

Bula everyone,

I am thinking of what you are going through now in Florida, Mexico, and the
Caribbean, and my heart just bleeds.

We await your reports on the impacts and how bad this has been, on any
promising signs, and on what survived, as well as reports on what worked or
equally as important what did not work for you!   This is vital information
needed to save the corals of the world, and its importance can not be
overestimated.

However, please do not get over-involved with your monitoring to look up!
Based on my experience here in Fiji, your few coral survivors might soon be
in rather extreme danger from super abundant and starving coral
predators, as the predator to prey ratio just got skewed very badly.  My
experience is that the predators can move in quickly, and your corals will
be facing hungry fireworms, snails, parrotfish, and butterflyfish.  For the
reefs where few corals remain, I feel that without human intervention, we
may lose many of these precious, most bleaching resistant corals.  So your
most important work lies ahead!

As coral death due to overabundant predators can happen quickly, we need to
focus on collections of coral samples as soon as the water temperature
drops. Even weekly predator removal might not be enough, and not many will
have enough manpower for that, as it takes so much time.  So for areas
where predators are crazy abundant, with almost no hope for the corals that
remain, I would feel no guilt violating standard precautionary protocols or
taking just 10-20%, and instead rescue entire colonies of particular
species of unbleached branching corals.  This is for the sake of the corals
and is precautionary when considering that these corals have just become
critically endangered. Of course these corals will never leave the ocean
and can be replanted back to the reef in a few month's time, once the coral
predators starve. This is precautionary.  Leave some behind and see if they
die if you like, and for some areas this may not be as important?

A coral rescue nursery can be made to elevate the corals on wire mesh, or
threaded onto ropes tied to metal frames.  As long as UV levels remain
high, these corals must be shaded under 30% standard nursery shade cloth.
For larger corals, I suggest that you try regular predator removal if you
can manage it, and wait a bit until UV levels drop and then if it appears
necessary to move them to safety, orient the colonies in their original
position within the rescue nursery, so tag the north side when they are
collected. In this way they will not bleach due to the changed light angle.
Larger corals do well simply placed onto wire mesh table tops. The
nurseries should be located in proximity to the reef so the juvenile fish
and surgeonfish will continue to clean the nursery.

We need every coral genotype which has survived to make it through these
tough times, and with enough biomass so that it can be duplicated to spread
extinction risk between nurseries, and later between restoration sites.
Your role and operational paradigm might need to become very different than
it was in the past?   A longer term objective in our renewed efforts might
be to increase the biomass of as many coral genotypes as possible, as
quickly as possible, with the goal of reestablishing sexual reproduction to
each impacted coral species via the creation of genetically diverse
nucleation patches on your coolest reefs, where the corals might fare
better next time.  Instead of planting large areas, focus on smaller
patches that can be monitored more closely and serve as better fish
habitat.  We continue to use epoxy coated A-frames for most of our
outplanting, made of heavy mesh of the type used for floor reinforcement in
construction.  A-frames elevate the fragments, results in very low
mortality and faster growth, and serves to increase fish habitat much
faster, and the fish in turn help keep the corals healthy.  So the entire
ecosystem comes to life faster than if we used fragments planted to the
substratum.

Ocean heat is intensifying, and the question we might ask ourselves now is:
will another heat wave hit Florida and the Caribbean again next year?   We
need to prepare for the worst and hope for the best.
For Australia and the South Pacific: The Caribbean should be our wakeup
call.  And BAD NEWS, Kiribati is already at record heat stress levels, and
so this indicates that the marine heat wave coming at us may be off-scale
for the rest of the Pacific as well.  The NOAA models, which in the past
performed very well, may be under-predicting this far out in time, like
they did for the Caribbean, and this is due to a changed baseline. The
ocean thermal anomaly continues to be 5 standard deviations or. 1.5C above
the 1982-2011 mean.  https://climatereanalyzer.org/clim/sst_daily/

This is the time to spread our risk, the time to collect and move as many
samples of heat adapted corals out to nurseries located in cooler waters,
and to create nurseries which are more easily shaded for all that we want
to survive what might be coming at us!

This will take courage, matched with action.

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/>