[Coral-List] Bleaching Surveys
Jim.Hendee at noaa.gov
Fri Dec 16 06:21:25 EST 2005
[I am forwarding this for Dr. Ernesto Weil, who was apparently having
problems sending this because the address he sent it from was not his
subscribed address <eweil at caribe.net>.]
From: Ernesto Weil <reefpal at gmail.com>
Dear Colleagues, I have sent this note four times in the last weeks but
it does not get to the list somehow. It has been rejected three times by
the administrator, I believe tjhis has to be a system problem, so I send
it directly to Jim so he can post it.
We just finished our disease-bleaching surveys in Bermuda and Grand
Cayman. No bleaching was observed in Bermuda. GCayman still had a few
totally bleached colonies of /Montastraea franksi/ and /Agaricia
lamarcki / down to 140 feet. All bleached colonies were still alive and
no mortality was observed. In shallower habitats, colonies of several
species are recovering their coloration.
From our travel and information gathered this summer and up to early
December, the only areas not affected by an intensive bleaching were
in the south-central Caribbean including the Netherland antilles
(Curacao, Bonaire, Aruba) and northern coast of Venezuela. Fortunately,
these are some of the best and most diverse reefs in the Caribbean.
Recently however, Steve Piontec from the Aquarium in Curacao and
colleagues from the Universidad Simon Bolivar in Venezuela, reported
that minor bleaching, with mostly paling colonies, in reefs off Curacao
and the northern coast of Venezuela was observed. Grenada, Barbados and
Tobago on the the south-east had substantial bleaching from our
observations and reports in the list. Near shore reef areas in the
northern coast of Colombia seem to have experienced minor bleaching
also. From Panama to Mexico bleaching was intensive and extensive as in
the northern Caribbean as you all know from the reports in the coral
list. Corals are now recovering their coloration in most areas.
Here in La Parguera, Puerto Rico, observations from the last two weeks
indicate that most large colonies of /Montastraea, Diploria,
Colpophyllia/, /Dendrogyra,/ and /Siderastrea /are showing coloration
recovery starting from colony edges with some large colonies with
colored patches all over. Many colonies still remain white. Some groups
had curious bleaching patterns ( /Porites astreoides/ bleached in
shallow and deep areas mostly but not at intermediate depths).
Most colonies of species that rerely bleach, bleached this year and are
still pretty much white or pale (/Mycetophyllia, Mussa, Scolymia,
Isphyllastrea /, etc).
The sad news, is that high mortalities of /Acropora palmata, //A.
cervicornis and Millepora spp. / have been observed in shallow areas of
three reefs. Partial mortality is common but many colonies are totally
dead. Some /A. palmata/ are showing signs of white band disease
underneath the colony branches, but most of them are bleached or showing
signs of necrosis and tissue "sloughing off" or "dislodging" from the
skeleton in most branches (shut down reaction??), even tissue that is
still colored is sloughing off. These colonies were doing great for
several years, surviving bouts of patchy necrosis and three
other bleaching events since 1998 until tgis year. In most
shallow habitats, all large stands and individual colonies of /Millepora
complanata/ and /M. alcicornis/ are dead and already covered by fine
filamentous turf algae. In the deeper reef habitats of inner and
mid-shelf reefs, high mortality of the platy /Undaria humilis /and /U.
purpurea/ was also observed.
As to exactly what caused the mortalities, there is no doubt that the
bleaching was part of it, but there are confounding factors that might
have exacerbated the impact. We had many days of heavy rains in the last
months (unusual for this area) which have lowered salinity levels in the
first 1-2 meters of the water column, lots of sediments coming from the
run-off waters and rivers upstream have also washed out to the reefs. In
late November, trade wind activity was high and even though the water
temperatures are coming down, heavy seas and surge are resuspending fine
sediments from the bottom. Visibility has been down to a couple of
meters in most reefs up to 3-4 km. offshore for two weeks now. TD
27 produced more surge and rain. We'll keep monitoring these reefs and
individually tagged colonies. .
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