[Coral-List] Responding to Coral Bleaching
abowdenkerby at gmail.com
Sat Sep 19 04:12:43 EDT 2015
Bula Dennis and others on the list,
Interesting observations, many of which have good merit. However, I find
that a paralysis of will can sometimes be the result of too much side
thinking and doubting. This massive bleaching will come and then it will
go very quickly, and it may not return for five years or a decade or so, so
study it now or perhaps lose the chance- none of us are getting any
The point I have tried to make is that we have an urgent situation at hand
that threatens coral reefs NOW. If this were a climate change event
occurring ten thousand years ago when human impacts were insignificant,
coral reefs would be ecologically balanced and certainly better capable of
adapting. But from what I have experienced, every reef is more or less
under some sort of human-induced stress that makes adaptation to climate
change much more difficult. I am proposing a completely new strategy that
gives people something to actually do about bleaching over the short term.
I have seen that it can make a very big difference.
Most of the adaptive potential of coral species to beaching rests with the
bleaching resistant coral colonies, but adaptation is for the most part
(based on my own experience), being prevented by over-abundance of coral
predators on reefs, which so often kill most of the surviving corals. This
is a testable hypothesis that could be an important part of the salvation
of coral reefs. Predator removal during and after bleaching also gives
conservationists and activists something to do to fight back, rather than
sitting on their butts and becoming depressed because there is nothing they
can do. People desperately need hope at this time, otherwise they may just
give up on coral reefs.
I am simply suggesting that for those who live near coral reefs, that they
might focus on what happens subsequently to a massive die off of
susceptible corals, knowing that the surviving resilient corals must
survive in order for the coral reefs to adapt to the new stressors.
Wherever 80-95% of the corals end up dead, high background numbers of COTS
and snails etc. seem to prevail nearly everywhere, and these predators have
the potential to kill everything (palatable) that survives the bleaching.
Ironically for Pacific reefs, in my experience, it is the Stegastes
damselfish that are absolutely essential in the post-bleaching survival of
corals- on many reefs their territories are the ONLY place where any
Acropora or Pocillopora will escape the COTS. They actively attack the
COTS and drive them away, as if the COTS were invading sea urchins trying
to steal their algae. Another easily tested hypothesis, although there is
an older paper documenting this behavior from Pacific Panama.
In the Caribbean, I have found that snails and fire worms rarely kill an
entire colony, and when they do it may take weeks for them to finish the
job. However, in the Pacific, a single COTS will kill a fist-sized or
plate-sized piece of coral every day/night, and will normally kill entire
colonies before moving on. They can also form fronts and kill every
coral that is tasty to them. It is fairly safe to postulate that if we
remove a thousand COTS, that we have saved roughly 300,000 corals per year
for several years. Therefore, COTS removal can be very effective as even a
one-off intervention to help deal with this emergency. We have an
opportunity to protect and nurture pockets of reef and to encourage
accelerated recovery. The development of resilience to future bleaching
events will then occur, as these pockets of health end up becoming filled
with thermally adapted corals. Of course the bigger picture issues must be
dealt with as well, but this approach can reinforce and support MPAs,
because without corals MPAs function poorly.
Whether COTS removal is an effective long-term strategy under normal
conditions was not my point of discussion. We sometimes do it for
community involvement as much as to save corals. Of course no-take MPAs
and nutrient control are better long-term solutions that address the root
causes of predator over-abundance, but you have to have a strategy to get
fishing community support, and this type of activity builds support
while offering a very real short-term solution to increase coral cover and
fish habitat, as Janis and Brooks and many others will testify.
Again, my original point is that we have an opportunity to act NOW, and so
I shared a new idea that has potential to motivate communities, NGOs, and
hopefully scientists, and that helps give the surviving corals a future and
the people involved more hope. The key element of the strategy is to keep
the precious corals that survive alive even after the bleaching abates, and
by whatever means that are at our disposal. This will include predator
removal and the collection and propagation of corals that thrive in spite
of hot water and post-stress disease.
Shouldn't we protect these survivors like we would precious gold and
diamonds? We put our precious cash and heirlooms into secure banks, and so
why not create secure "gene bank nurseries" for cultivating resilient
corals (temperature, disease, etc.). This is exactly what we have done in
Belize and the Dominican Republic, and we are then using second generation
fragments trimmed from the nurseries, to restore coral cover to rather
sizable patches within no-take MPAs where the Acropora corals have not
returned in spite of other types of management.
We did all of this in spite of opposition from certain of you within the
coral reef research community, who went so far as to publish a formal
position paper that dismissed our efforts, based on incorrect assumptions
about what we were actually doing. Of course the opposition made it very
difficult to access funding. I hope that our ultimate success has now made
it clear that certainly there is room for every approach.
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