Reefs at Risk.

Precht,Bill BPrecht at
Mon Jun 29 18:30:20 EDT 1998

Dear Group:

I just returned to find my email inbox loaded with various views on this
question of "reefs at risk"

Since a few of the examples discussed included some of my own research
and/or research areas, I felt that I needed to throw in my two-cents

Recently, I was having a discussion with Sen. Bob Graham (FL) with
regards to the "coral reef crisis" in Florida.  Cutting to the quick,
Sen. Graham asked me if what was going on in Florida was happening
elsewhere throughout the Caribbean and western Atlantic?  The answer is
yes.  An emphatic YES!  Although this in itself is very disturbing,
trying to blame Florida's coral reef woes on the sugar industry or
primitive septic systems in the Keys is out of place and off target.
I'm not saying these should not be included in a comprehensive
management plan for a sustainable south Florida...they should.  But as
Steven Miller has made clear the "chicken little" approach, while it
sells memberships to The Cousteau Society, Reef Relief and others, does
not offer much in the way of rigorous quality science or to finding
common ground for solutions... and these should not be mutually
exclusive... I hope quality science will be at the forefront of future
management decisions and solutions.  

The same increases in macroalgae we are seeing across the Florida reef
tract are being observed throughout the region (Almost without
exception!).  The two prevailing paradigms for this increase in seaweeds
include the loss of herbivores(overfishing) and nutrification
(decreasing water quality).  Trying to tease out the most important of
these two on a regional scale (finding the smoking gun) has proved to be
troublesome and problematic.  Certainly, each of these are important on
some reefs, while on others both are working in concert towards reef
decline.  However, on a regional basis the one common link has been
declining coral cover.  Specifically, the mortality of the acroporids on
a regional scale.  Over the past two decades these corals have succumbed
to disease (white syndromes) as well as physical damage thereby opening
space for the colonization by rapidly recruiting and fast growing algal
species.  This has occurred on reefs far from population centers on some
of the most "pristine" and remote reefs of the entire region.  In the
early 1980's as White Band Disease obliterated A. cervicornis on the
Florida reef tract, the same malaise affected reefs of the eastern
Bahamas.   These Bahamian reefs are bathed in some of the most
oligotrophic waters of the western Atlantic.  No nearby river systems,
no burgeoning population on these islands, no deforestation problems, no
sugarcane industry, plenty of herbivorous fish, etc....  In comparing
similar habitats (apples to apples) these reefs look no different today
than their Florida counterparts...lots of A. cervicornis rubble covered
with macroalgae (in fact as Bob Steneck points out many of these reefs
are in far worse shape than the Florida examples), while stands of other
corals such as Montastrea spp. appear to be thriving.  This is the same
in Bonaire, Belize, Columbia, and so on...  Rich Aronson and I have been
struggling with this question for the last decade and a half and have
just completed a paper that discusses this in some detail (Aronson and
Precht, in-press, Evolutionary paleoecology of Caribbean coral reefs in
Allmon and Bottjer (eds).The Ecological Context of Macroevolutionary
Change. Columbia University Press).  

Certainly, Florida's reefs are in crisis...but than so is every reef in
the Caribbean.  Trying to pick the 12 most endangered is way too
subjective, even with a list of discriminators...everybody has a
favorite reef which brings me the second part of my discussion... The
Reefs of Belize.

First off I'd like to clarify one of Les Kaufman's points in an earlier
discussion.  Les stated "Belize was unusual in that when the acorporids
began to vanish, there was an endemic agariciid...that could serve as a
partial functional replacement, and it did."  Although he is partially
correct (see Aronson and Precht, 1997, Stasis, biological disturbance,
and community structure of a Holocene coral reef: Paleobiology
23(3):326-346.), the reefs that were replaced by agariciids were
lagoonal reef complexes in central Belize.  The main Belizean Barrier
Reef and offshore Atolls, lost A.cervicornis during more or less the
same time period.  However, on these reefs the replacement species was
macroalgae just like most of the rest of the Caribbean including
Florida.  This coral-to-macroalgal scenario for Belize will be shown in
an upcoming "reef site" in CORAL REEFS by McClanahan et al.

Now turning to the reefs of southern Belize.  The Maya hinterland is
being deforested at a staggering rate, mostly for agri-development.
This has dramatically increased the amount of sediment laden water
entering the southern Belize lagoon.  This coupled with the southward
sloping configuration of the Belize platform, puts reefs that are
already submerged (incipiently drowned) to a depth of >8m, in a position
where they will founder and drown in the face of deleterious water
quality.  Without holistic management of the Maya Mountain watershed the
effects on reefs from the southern Belize lagoon will be devastating.
(Also remember that the fast growing A. cervicornis has been almost
completely decimated from these reefs as well due to WBD)  

So where do we go from here?????

Best Management Practices must be employed both on local and regional
scales to be most effective.  We must value all reef areas equally and
not score Florida above Belize or vice versa... We must understand the
pivotal role of coral mortality, especially mortality due to disease.
We must understand the causes of coral disease... especially if there is
a link to human's which many suspect...We must understand the
recruitment and regeneration of coral species in the wake of these
disturbances... We must be able to tease out those things that can be
managed with those that can not... and finally WE MUST STOP POINTING OUR
THERE IS A LINK TO THE SYMPTOM.  Citing decreasing water quality as the
main issue is a cop out.  Plaudits to Thad Murdoch for an interesting
review of his Keys Wide data.

Bill Precht
LAW Engineering & Environmental Services, Inc.
5845 NW 158th Street
Miami Lakes, FL  33014
ph (305)826-5588
fax (305) 826-1799

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