Land-based stresses on reefs.

Mike Risk riskmj at
Fri Feb 22 09:19:00 EST 2002

There was discussion earlier on this list about the future of reefs. Some
interesting and controversial opinions were exchanged, and some positions
challenged. Recent data seem to shed light on this issue, allowing some

Bob Buddemeier (posting, Jan. 16) gives me entirely too much credit for
policies and
procedures on monitoring. I advise several countries, but there is no more
they will take my advice than there is that readers of this list will. No,
the credit for the
present state of reef management, at least in the USA, must be given where
credit is
due: to those who have put their research careers to one side, and built
reputations on
organising international conferences, on meeting and schmoozing with the
development banks, and on lobbying governments. They deserve all the credit.
has left the grunt work of science to the rest of us sweat-stained wretches,
as can be
seen in the results reported here.

An abstract has been accepted for presentation at this summer's ASLO
meeting, and
may be viewed on their website: Ward-Paige and Risk, BIOEROSION SURVEYS ON
THE REEFS. To summarise the findings: a bright-orange coral-killing
sponge, Cliona delitrix, previously shown (almost 20 years ago) to be a
bioindicator, is all over the Florida Reef Tract. As coral cover has
decreased, sponge
abundance has increased. Stable nitrogen isotopic analyses allow a link to

These findings reinforce several points made earlier, i.e.:

1. Reef monitoring projects need to be interdisciplinary in planning and in
staffing. Most
are designed and run by coral biologists. Don't get me wrong, some of my
best friends
are coral biologists-but it seems strange to have overlooked a bright orange
critter that
thrives on sewage and kills coral. Although C. delitrix is Caribbean in
distribution, a
related species, C. viridis, is a dominant benthic organism on Australian
patch reefs,
and no Australian monitoring program reports it. Grazing pressure has little
or nothing
to do with abundance of either organism.

2. Given the rate of decline, monitoring programs need to shift to a
approach-this is also more suited to community-based management. Listers
should look
into Mark Erdmann's wonderful stomatopod project, in Sulawesi, in which
village women
are taught how to monitor their own reefs as they glean for food.

3. Monitoring programs, reef models and management schemes that do not
coverage of bioerosion are not dealing with the full deck and will not
dependable results. They all need serious remedial work. (Full credit goes
to the FMRI
program-in alphabetical order, Walt Jaap, Vlad Kosmynin, Jim Porter, Jenni
and Phil Dustan in the early stages. They were already running an excellent
and saw the need for a bioerosion component.)

4. Time spent discussing and writing about "global change" would better be
finding solutions to more immediate problems. My prediction-most gone by
seem well on the way to being correct. Florida has lost 38% of its coral
cover in the last
4 years, and in SE Asia a regional mass extinction of corals is well under
way. Alkalinity
hasn't budged-these processes are driven by land-based sources.

5. MPA's need to be established well away from land-based sources.

There may be some small amount of good news. At the same meeting, I will
present an
abstract showing how the relative impacts of sewage and siltation can be
for reefs where no baseline data exist, one that can be used by local
communities. It's
easy: plot coral tissue N-15 values against % insoluble residues. Techniques
been around for decades. So a preliminary evaluation of the major land-based
on a reef should cost about $100 Canadian. The insoluble residue work can be
done in
any high school lab, send the N-15's out, $20 a pop. (That's POP, not poop.)

Those of you who would like to see what Cliona delitrix looks like-it's
really quite a
pretty organism, despite its disgusting diet-let me know and one of
Christine or I will
send you a .jpg

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