[Coral-List] Vanishing Corals

[Douglas Fenner]

This post is way too long, so an abstract:

Although this is a good web page overall,

1. the fact that sessile coral reef animals produce a vast array of novel
chemicals in self-defense does not mean that "many" medicines have been
derived from such chemicals, because approved medicines must be found to be
both effective and safe, and most tested chemicals turn out not to be one
or the other or both, and for unknown reasons that is particularly true of
chemicals from coral reefs.  Only a handful of approved medicines have been
derived from coral reefs.

2.  Although coral bleaching and mortality are strongly correlated with sea
surface temperatures, the correlation is not perfect, and it is still
necessary to confirm bleaching with direct observations in the water.
Further, distinguishing brand newly dead coral from fully bleached coral is
very difficult if the coral is completely white and impossible to
distinguish from the air.  However, both are bad for corals.

3. the statement that "14% of the world's corals have been lost" is based
on verbal reports from scientists, and is not directly based on data.  I
contend that "the death of the world's corals has been greatly exaggerated"
because in a fair number of places (none that I know of in the Caribbean),
reefs have recovered coral cover even after huge losses.  Not true
everywhere, and some have been documented to have recovered cover but not
the original community, and most importantly, the fact that coral losses
have sometimes been followed by recovery of coral cover, does NOT mean that
corals are not threatened with massive losses in the future, they obviously
are.


While this appears to me to be overall a very good web page, I would like
to caution people about one thing.

The page states "Coral reefs also help protect human life and property."
and " Second, they are the source of many cutting-edge medicines
<https://oceanservice.noaa.gov/facts/coral_medicine.html>."  The latter is
a very popular myth, but it is not true.  You can check the link, it leads
to a page that simply states this proposition, but gives no evidence to
back it up.

Everyone agrees that coral reef organisms, particularly sponges, sea
squirts and soft corals contain vast numbers of novel chemical
compounds, including many entirely novel classes of chemicals.  There are
many peer-reviewed articles documenting this.  It is true that sessile reef
animals use them for defense.  It is also true that there have been
programs to test as many of these compounds as possible for medical use.
However, it is a myth that many approved medicines have been derived from
these chemicals.  Try finding a list of approved and available medicines
derived from these chemicals.  No one can list "many", I've only seen lists
of about two or three.  As we learned in the pandemic, medicines must be
tested and shown to be both safe and effective to be approved for use.
Drug companies commonly state that the process of testing chemicals for
medical use is long and costly, because most chemicals turn out to
either not be safe or not be effective, or both.  The overwhelming majority
of these chemicals from coral reef animals are not safe or not effective or
both.  The sessile reef animals have been selected to produce chemicals
that deter predation, which either taste bad or are toxic, and many are
both.  Toxic chemicals are not safe to use as medicines.  For reasons we
don't understand, very few if any are effective against diseases like
cancer, though huge numbers have been tested.
       It is true as far as I know that a good number of approved drugs are
based on chemicals from tropical rainforests.  But for unknown reasons,
that is not the case for coral reef chemicals.  As far as I know, no one
seems to know why, and the fact that few approved drugs have come from
coral reefs is not widely acknowledged, perhaps because it is not a popular
idea.
       People use logic to go from the fact that these animals produce a
huge variety of chemicals to protect themselves, to deducing that therefore
there must be huge numbers of useful medicines that can be derived from
them.  There is also good motivation to provide strong reasons to protect
coral reefs, that's not bad.  But the empirical evidence to support that
idea is lacking, there are very very few approved medicines derived from
coral reef organisms in spite of programs to test large numbers of these
chemicals.  The statement that there are, is a very popular myth.  Anyone
who states it needs to back it up by citing approved medicines that are
based on chemicals from coral reef organisms.

     The other thought I have is that there is a difference between
monitoring sea surface temperatures by satellite and actual bleaching
and/or mortality of corals.  The two are of course very much connected,
increased SST's do generally predict bleaching and may cause coral death.
But the correlation isn't perfect, and bleaching and mortality still need
to be verified in the field.
       Also, bleaching has been observed from low-level airplane flights,
particularly on the Great Barrier Reef, which is so huge that in-water
verification for the whole reef is impossible.  But note, both bleached
corals and newly dead corals are white.  Seeing white corals from the air
indicates coral in deep trouble, but distinguishing bleached from newly
dead from the air is likely not possible.  In fact, in the water,
distinguishing them is still very difficult even when they are inches from
your face.  When a colony is only partly bleached, then you know for sure
it is alive.  But fully bleached tissue is transparent and quite difficult
to see.  Not impossible, but not easy even if it is right in front of your
eyes.  As soon as a coral starts to have filamentous algae growing on it,
which happens within just a few days in shallow water in the powerful
tropical sun, then it becomes very easy to spot dead corals.  That is
likely slower in deeper water.  Just a small precautionary tale here.

      And last, the article states that "14% of the corals have
disappeared."  If you look up the source, it comes from an older statement
that is based on what many coral reef scientists have said privately to one
person.  It doesn't come from actual data from coral reef monitoring.  A
 point I've made before could be summarized by saying that "The death of
the world's coral reefs has been greatly exaggerated" which is a paraphrase
of a statement by Mark Twain long ago when a newspaper reported his
supposed death.  (I do not mean that people have deliberately exaggerated,
but the data to support that kind of statement has been selectively chosen,
and cherry-picks the actual data, though usually not deliberately)  The
decline has been worst in the Caribbean, no doubt that is very real.  There
have been many many reports of coral deaths and in some places vast losses
of coral reef cover, one of the most famous was on the Great Barrier Reef.
BUT, usually people neglect to mention that in some or many of these
places, coral cover has recovered.  On the GBR it is now as high as it has
ever been since monitoring began, as shown by the graph from the AIMS
monitoring program on the GBR, actual data (the graph is on their
website).  It is worth mentioning that none of the places that have
recovered are in the Caribbean to my knowledge.  I believe there are also
places in the Indo-Pacific that have not recovered.  It is also the case
that the point many have made is true that recovery of coral cover does not
mean that the original coral composition has been recovered.  If there has
been loss of the largest coral colonies like the giant massive *Porites*,
then recovery of the original coral community would be physically
impossible as was first pointed out to my knowledge by Terry Done long,
long ago.  That's because the largest Porites colonies are hundreds to many
hundreds of years old, and the mortality was much more recent than that.
There are reports of places where coral cover has recovered but the
composition is now different.  Those are the exception not the rule so far,
but for the other areas usually there is no data on how the coral community
may have changed, and therefore community changes may be much more common
than have been reported (or not, we don't know yet).  Importantly, the past
is not always a good predictor of the future, especially in this case,
because we know, there are mountains of evidence, that the climate is
changing drastically and that rising temperatures are a HUGE threat to the
future of coral reefs.  So it is not necessary to claim that all or many
coral reefs have been badly degraded to support the view that the future
for corals is extremely threatening (and a statement that 14% of corals
have died may be true but many may have been replaced by new living
corals)..  The fact that some coral communities have recovered coral cover
is NOT incompatible with a very scary future that likely will have the vast
majority of corals killed world -wide.  Although that appears to be the
most likely future outcome, there is good evidence that corals have some
ability to acclimate and/or evolutionarily adapt to
increased temperatures.  It appears at this time to be most likely that if
temperatures rise too fast or too much, corals will be devastated, and so
far we are on course to have that happen, measures to reduce emissions have
so far been woefully inadequate.  If we manage to greatly reduce the rate
and amount of warming, it is possible that some corals may be able to
survive that.  And as scientists, we MUST acknowledge the facts and deal
with them, that is our first responsibility, I claim.

Cheers, Doug




On Sun, Jul 9, 2023 at 1:45 AM Vassil Zlatarski via Coral-List <
coral-list at coral.aoml.noaa.gov> wrote:

> Hope of interest:
>
>
> https://climate.nasa.gov/explore/ask-nasa-climate/3273/vanishing-corals-nasa-data-helps-track-coral-reefs/?utm_source=newsletter&utm_medium=email&utm_campaign=monthly+newsletter
>
> Cheers,
>
> Vassil
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