[Coral-List] Vietnam bans scuba diving to protect a coral reef

Douglas Fenner douglasfennertassi at gmail.com
Thu Jul 14 15:44:35 UTC 2022

     I agree with much of what you say.  I used to study the reefs in
Cozumel, Mexico.  The reefs that people dive on there are just 15 miles
long, they used to get 2000 dives a day for most of the year.  Hurricane
Gilbert was the strongest hurricane on record in the Caribbean when it
approached Cozumel.  After the hurricane, the coral there recovered,
improving in spite of lots of diving.  Doesn't mean divers do no damage.
But it suggests that in a list of different threats to coral reefs in order
of how much damage they do, diving may not be high on the list.  Obviously,
the amount of damage depends on how divers conduct themselves, as well as
how many divers there are, and in some areas divers may do more damage per
diver than other places.  There are peer-reviewed published papers
documenting diver damage, and snorkeler damage as well.  But much of the
world's reefs have very few if any divers.  For instance, on the Great
Barrier Reef, which is over 2000 miles long, most diving is concentrated in
the relatively tiny areas around platforms which dive boats take divers and
snorkelers to.  At the northern end of the GBR there are almost no people
on the land and no diving, fishing, or other humans doing things to reefs
there, yet a few years ago bleaching killed a significant fraction of the
corals there, surely billions of colonies.  The coral reefs in Florida are
minute (with heavy diving pressure), they are so small you could lose them
easily in the Great Barrier Reef, or Indonesia's reefs, or the
Tuamotu atolls of French Polynesia, or even the atolls of the Marshall
Islands, and there are lots more such places.  Of course, for high-value
areas of coral reefs where there are lots of divers, diver damage is much
more of a concern, a legitimate concern.
         It is certainly true that coral diseases have been documented to
have done a lot of damage to Caribbean and Florida corals.  My
understanding is that one disease (white band) caused much of the mortality
of two of the three most dominant corals in that area, staghorn and
elkhorn.  And a new disease is killing lots more corals other than those
two species there.  It is my understanding that the Indo-Pacific, which is
vastly larger than the Caribbean, has not had such huge, widespread coral
mortality from coral diseases.  I certainly haven't seen it.  Yet.  There
are plenty of diseases in the Indo-Pacific, if I remember, there is a study
documenting 30 coral diseases in New Caledonia alone, two or three more
times as many as the entire Caribbean has (Aeby et al, 2016).  Although
disease does not seem to have caused widespread mortality in the
Indo-Pacific so far, nothing compared to what bleaching has done there,
many of us are concerned that the Indo-Pacific disease might in the future
go the way of the Caribbean and Florida.  Might or might not.  At this
point, bleaching has killed far more in the Indo-Pacific than disease, as
far as I know.
         There is lots of hard evidence of massive coral mortality from
mass bleaching events, including about 16% of the world's reefs badly
damaged by bleaching in 1998, massive evidence that higher water
temperatures are the primary cause of mass coral bleaching, and that sea
surface temperatures are rising around the world, including in areas with
coral reefs.  There is also published hard evidence that the number and
intensity of mass coral bleaching events have been increasing along with
water temperatures.  Many or most scientists studying coral reefs are of
the view that the evidence indicates that mass coral bleaching from high
water temperatures which global warming (which is real) is making worse, is
the greatest single threat to coral reefs around the world.  Diver damage
on the world's reefs does not compare, it is many orders of magnitude
      Why do you bring up your demonstration with oil?  What does that have
to do with diver damage?  Did someone make the accusation that crude oil
had killed a lot of the world's corals?  You've talked before about your
story of immersing a living coral in crude oil.  Can you point us to your
peer-reviewed published paper on that anecdote, or the one where someone
sprayed oil on corals when they were exposed to air at low tide, neither of
which did the corals any harm?  Can you point us to a review paper
published in a peer-reviewed journal that reviews the effects of oil on
living corals and which shows that it does not harm them?  If I remember,
there was a peer-reviewed paper published on an oil spill in the Panamanian
Caribbean in which it was documented to have killed corals.  Reference
below (Jackson et al, 1989).  Doesn't that and other evidence show that oil
can in fact damage or kill corals?  Are there experiments where people put
oil in the water in an aquarium with living coral and find that it has no
effects on the living coral?  Please point us to those studies published in
peer-reviewed journals.  It appears to me that your anecdote may be an
exercise in cherry-picking evidence, perhaps you'd like to demonstrate that
it is not.

       Cheers,  Doug

Jackson, J. B. C. et al. 1989. Ecological effects of a major oil spill on
Panamanian coastal marine communities. Science 243: 37-44.

Aeby, G., Tribollet, A., Lasne, G., and Work, T. 2016. Assessing threats
from coral and crustose coralline algae disease on the reefs of New
Caledonia. Marine and Freshwater Research 67: 455-465.

On Wed, Jul 13, 2022 at 10:40 AM Eugene Shinn via Coral-List <
coral-list at coral.aoml.noaa.gov> wrote:

> Dear Listers, Our reef coral problems are not all caused by divers.
> Something else is causing the diseases and it is pretty much world-wide.
> Before the late 1970s one could touch, break, and do many things we
> would not do today and the corals just kept growing. I know because I
> did many of those things during the 1960s when I was measuring growth
> rates. Before going to Australia to testify in the Great Barrier reef
> hearings I submerged Staghorn coral in Louisiana crude oil for an hour.
> It grew just fine when it was placed back on the bottom. I was as
> surprised as anyone.  An Australian researcher testifying in Australia
> using a back pack sprayer sprayed crude oil on exposed corals at low
> tide and they grew just fine when the tide came back in. I an confident
> that it was not touching that killed corals after the early 1980s, it
> was something else that I have propsed many times. The research needed
> to determine that, “something else” has yet to be conducted. Instead, we
> just blame everything we can think of. Now it is those darn divers. If
> we keep it up we may have to ban diving in the Florida Keys. Careful
> what you wish for. Gene
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