[Coral-List] What do coral reef scientists perceive are the major threats to Caribbean coral reefs?
douglasfennertassi at gmail.com
Sat Apr 19 06:01:41 EDT 2014
Lionfish are currently an important introduced species in the
Caribbean, and snowflake coral (Carijoa reesi) in Hawaii is a problem,
along with a couple others (a sponge, Mycale, seems to be invasive).
However, invasive species in the Indo-Pacific are quite minor so far
compared to other threats, and the Indo-Pacific is the vast majority
of coral reef area. Compare with global warming: El Nino plus the
Indian Ocean Dipole caused enormous coral mortality in the Indian
Ocean in 1998, an estimated total with other areas of 16% of the
world's coral, a harbinger of things to come as temperatures rise and
El Nino warming events are on top of the warming trend. Also,
compared to many terrestrial environments where there are loads of
introduced species (cane toads, brown tree snakes, giant African
snails, predatory snails, vines and all sorts of other plants, etc
etc), some of which like the brown tree snakes in Guam and the
introduced mosquitoes and avian malaria in Hawaii do enormous damage.
Coral reefs have gotten off relatively lightly in introduced species
compared to terrestrial environments, but the lionfish are a reminder
that the reefs may simply be behind the terrestrial environments and
may have a future more similar to them. Just as the Indo-Pacific may
have a future with coral diseases as nasty as the Caribbean has had.
In time it will become clear whether the trends are just behind, or
The Reefs at Risk program evaluated threats to reefs, and
concluded that overfishing plus destructive fishing was the greatest
local threat, closely followed by land based pollution (if I remember
correctly). Reefs at Risk is online, a simple search should find it.
Anybody who has seen reefs flattened by blast fishing knows it is an
important threat, and it is widespread in two of the countries that
have some of the most of the world's reefs, Indonesia and the
Philippines. In addition, overfishing is so prevalent on reefs around
the world, that almost all of the world's reefs have at least some
species of fish that are overfished, which usually are the largest
and/or predatory species, but can in some locations include almost all
species as large or larger than a fish sandwich or even a teabag.
Many people (though not all by any means) working on reefs, think that
the removal of herbivorous fish is part of the cause of, or the most
important cause of, the rise of algae (macro and otherwise) on reefs,
which because they compete with corals, is considered part of the
cause of the loss of corals. Such ideas are based on quite a bit of
evidence, though the evidence is complicated and there is evidence
supporting a role of nutrients as well. Fishing is surely one of the
more important threats to reefs, as also recognized by many reviews,
including the very extensive NOAA review of the corals petitioned for
endangered species status (Brainard, et al. 2011, available open
access on a NOAA website).
Population and development are ultimate causes, not proximal
causes. They act by increasing the amount of proximal causes like
fishing, land based pollution, climate change, introduced species,
etc. They are the ultimate drivers, incredibly large numbers of
people doing things that impact reefs. However, to turn around
population growth, while a necessary goal, will take way, way too
long, it will take most of the rest of this century and maybe beyond
to stop the growth of population, let alone reduce population.
(Population growth slowing is likely to happen naturally, if more
people are lifted out of poverty and women get more education and more
control of their own reproduction.) Most (but hopefully not all)
corals will be quite dead by then if we don't get more of the
important proximal causes of reef decline under control before then.
The list is long of things humans do that damage reefs. I
completely agree that climate change is one of the top future threats,
if not the single largest future threat.
Gene is right that at different times, those working on reefs
have raised alarms about many different threats. There is abundant
evidence that many or most of those have done a lot of damage to reefs
at one place or time or another. I'd add crown-of-thorns starfish,
which when they first came as an outbreak, a horde of them devouring
everything in the way of corals in sight on the central Great Barrier
Reef, looked like they might eat most of the coral of the entire
Indo-Pacific, particularly when outbreaks in places like Japan and
many other places happened as well. Recently it has been recognized
as one of the major causes of the decline of the Great Barrier Reef,
which due to its huge size makes it very important, but we no longer
think that crown-of-thorns is going to march around the Indo-Pacific
killing most everything. We're glad it isn't, we've got enough
trouble as it is.
On Thu, Apr 17, 2014 at 1:38 AM, Magnus Johnson <m.johnson at hull.ac.uk> wrote:
> Plastics + POPs? Invasive species? These are two threats that, like climate change, we will struggle to deal with and should be on your list.
> I think fishing, while it should be there, should be bottom of the list! Also population growth (1 australian ~ 12.5 indians in terms of carbon emissions as an indicator) in my opinion is, like fishing, one of the obvious rather than most potent threats.
> What about global inequality? How can you stop a man or woman going fishing on a reef to feed their children when the only alternative you can offer is cocacola-isation of their cultures and poorly paid servant labour to the fat western middle classes?
> -----Original Message-----
> From: coral-list-bounces at coral.aoml.noaa.gov [mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Ellen McRae
> Sent: 17 April 2014 03:04
> To: Steve Mussman; coral-list
> Subject: Re: [Coral-List] What do coral reef scientists perceive are the major threats to Caribbean coral reefs?
> Hello Steve and all
> Nrs 2 and 7 are Disease in your list. Could one of them be replaced with Pollution (land and sea-based); also add UV/atmospheric degradation?
> Best wishes,
> Ellen McRae
> On Tue, Apr 15, 2014 at 7:52 AM, Steve Mussman <sealab at earthlink.net> wrote:
> > While it is certainly a challenge to clearly portray the synergy of
> > impacts
> > that multiple stressors have on coral reefs without confusing
> > people into
> > inertia, the issue is being greatly distorted by a deliberate campaign
> > designed to continue the debate based on promoting the false proposition
> > that there is a substantial level of scientific disunity. I donât
> > really see
> > that beyond the fringes and would argue that a clear consensus exists.
> > The
> > eleven threats listed below seem to provide obvious support for
> > Alina's case
> > for primacy of human causation. So while people may be the
> > solution, they
> > can't possibly provide a satisfactory resolution without first
> > recognizing
> > and accepting their role as primary drivers of the problem at hand.
> > 1.Ocean warming 2.Disease 3.Ocean acidification 4.Overfishing
> > 5.Sedimentation 6.Coral bleaching 7.Disease 8.Coastal development
> > 9.Human
> > population growth 10.Algal competition 11.Laws and enforcement.
> > Regards,
> > Steve
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