[Coral-List] Reassessing Coral Reefs: Reply To S. Mussman
douglasfennertassi at gmail.com
Mon Apr 20 18:22:26 EDT 2015
My statement wasn't meant to apply to just the heavily dived areas. It was
meant to apply to the world's coral reefs as a whole. Most of which have
very few if any divers ever. Diving is concentrated in tiny areas,
compared to the size of the world's reefs, though when you're diving there,
they may not seem tiny.
I have no doubt that in many heavily dived areas, there is significant
diver damage, I don't dispute that, and I support reducing it. I have,
however, seen corals recovering from hurricane (Gilbert) damage in Cozumel
in spite of 2000 dives a day on 15 miles of reef. That tells me that
diving was much less damaging than the hurricane was. That may not be a
common experience around areas of heavy diver usage, and may in part be due
to the currents and drift diving which may reduce diver contact in Cozumel.
An awful lot of reef that has little or no diving has been going
downhill. Much of the Caribbean, and now the Great Barrier Reef are
outstanding examples. The primary cause of initial Caribbean decline was
white band disease on Acropora. We don't know the cause of that, but it
wasn't divers, the disease killed corals in places with no divers. The
causes of GBR decline do not include diver damage, as far as I know.
Diving is almost completely restricted to near diving platforms that
operators set up on the outer reefs, tiny areas compared to the vast reef
system. Mass coral bleaching, crown-of-thorns, and cyclones are the
primary culprits if I remember. Bleaching caused by hot water events on
top of global warming, the crown-of-thorns outbreaks enabled by nutrient
runoff from human activities on land, and increased cyclones may be due to
shifting weather patterns or a streak of bad luck. The decline was not
caused by diving.
Reducing diver damage is good. It will help save small areas of
economically valuable reefs, for perhaps as much as a few decades. That
can help buy time for those areas, time for us to get the big problems
under control. But it won't save the world's coral reefs, most of which
have very little or no diving, and it will only temporarily save the dive
spots if we don't get the big problems under control. I agree that
reducing diver impact is a central part of saving heavily dived reefs, even
if it is a very minor part of saving the world's reefs. It is a good
start, but we have to do much, much more or we are going to just keep
loosing more and more coral.
On Sat, Apr 18, 2015 at 5:12 AM, Alevizon, William Stephen <
alevizonws at cofc.edu> wrote:
> Steve -
> Re: your comment, "But William, it's not humans as divers that are doing
> the most damage. It's a host of other human activities that are destroying
> the reefs."
> First, I'd like to see some actual evidence that statement is true, at the
> scale of many heavily (by recreational divers) used localized reef sites.
> Second, even if true, that does not mean that we can just ignore all but
> the most destructive cause(s), even if those could be unambiguously
> In the few instances (e.g., Saba, Bonaire, Cabo Pulmo) where diver numbers
> are strictly controlled, the benefits in terms of reef health have been
> But, while diver "awareness" and pre-dive briefings have been shown to
> reduce damage on a per diver basis in some (not all) cases, but such
> benefits are negated where the number of dives/year remains excessive.
> In short, the dive industry and/or sport divers themselves cannot and will
> not effectively address the issue of too many divers on a reef. Only MPA
> management has the authority and means to control this most damaging impact
> of recreational diving.
> William S. Alevizon
> Research Associate
> Dept. of Biology
> College of Charleston
> 58 Coming St.
> Charleston, S.C. 29424
> Coral-List mailing list
> Coral-List at coral.aoml.noaa.gov
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