[Coral-List] RMI COT update and non-geostructural coral communities

John McManus jmcmanus at rsmas.miami.edu
Tue Apr 19 17:36:32 EDT 2005

We had a lot of experience with COTS in the Philippines, particularly during
outbreaks in the late 70's. 

COTS tended to eat Acropora and Montipora in low COTS densities. However,
during major outbreaks on small non-geostructural coral communities, they
would eat the tissue off nearly every hard coral, including Porites
(branching, encrusting, and massive). The densities you describe can become
much higher, to where there is a COTS nearly everywhere you look. 

I use here the term "non-geostructural coral community", to replace the
somewhat unsatisfactory "non-structural coral communities/stands" and
"non-reef coral communities/stands" I have used in the past. Thomas Goreau
Senior (Jamaica paper and another -- maybe Saipan) clearly differentiated
between "coral reefs" (limestone structures with associated ecosystems) from
"coral communities", wherein coral grows on substrate other than
geomorphologically significant limestone structures (e.g. gravel, boulders,
exposed rock ridges). Later, however, "coral community" was applied in
papers to mean coral assemblages on coral reefs. The differentiation is
important for reminding us that many corals grow in places other than
structural coral reefs. In the early ReefBase, we included both
geostructural and non-geostructural communities under the common term "coral
reefs", and the difference was used to demarcate limits to reefal
calcification in a paper by Kleypas et al. Note, though, that
non-geomorphological coral communities are extremely common around the
coastlines of SE Asia, and there may be more coral growing on them than on
geostructural reefs. Most of these communities do not show up in aerial
photos and charts (and those few that do are often mistaken for
geostructural reefs), and so are not generally included in the chart-based
estimates of reef coverage around the world However, the larger reef area
estimates in papers by SV Smith, John Munro and J. Kleypas were based on
proportions of shelves covered by corals, and so would have included them.
These small communities are easily overrun by COTS, which then disappear
suddenly, presumably from starvation. However, on a large true geostructural
reef of many sq. km, I'm not sure that "starvation" is necessarily going to
happen before major coral losses. Our colleagues from the GBR would know
more about that.

 *** Please note new phone numbers (361 now 421) ***
John W. McManus, PhD.
Professor, Marine Biology and Fisheries
Director, National Center for Caribbean Coral Reef Research (NCORE)
Rosenstiel School of Marine and Atmospheric Science
4600 Rickenbacker Causeway, Miami, FL, 33149
305-421-4814, 305-421-4820,       Fax: 305-421-4910
jmcmanus at rsmas.miami.edu

-----Original Message-----
From: coral-list-bounces at coral.aoml.noaa.gov
[mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Dean Jacobson
Sent: Sunday, April 17, 2005 7:56 PM
To: Coral List
Subject: [Coral-List] RMI COT update


Our COT outbreak has reached a "plague" type scenario.
 I finally checked on the reef (SW Majuro lagoon
fringing reef) where 900 COTs were previously killed
in local SCUBA interventions that I organized last
August.  (I estimated a density of 1000-2000 COTs per
km of shoreline).  While there are some surviving
Acroporas, over 90% have been eaten.  (The abundant
smaller Acroporas, i.e. A. digitifera, on the reef
flat are unaffected). The COTs are now turning on
Pocillopora eydoxi, Pavona duerdeni, Lobophyllia and
especially Porites cf. lobata, the most abundant
species next to Acropora.  The only coral not attacked
is P. rus, which dominates this site (Acropora formed
a narrow band between 1-4 meters depth, replaced by P.
rus in deeper water).  This is the first time I have
seen entire massive Porites colonies killed;
previously there was minor "nibbling around the edges"
of such colonies.

Has anyone else seen such significant Porites

I have heard it suggested that a COT outbreak should
be left to run it course, with starvation eventually
ending the outbreak, but the prospect of the loss of
ancient Porites heads is sobering.  I hope to renew
the intervention, to save some of the slow growing
forms, using night snorkeling around a tender boat. 
Last year the fisheries ministry provided boat and
fuel for several intervention dives. Although I made
an appeal to the local government last year (showing a
video of collection techniques)I unfortunately had no
response, with no native divers getting involved.  

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