Bleaching and Exfoliation in Acropora
yfadlal at kfupm.edu.sa
Thu Jun 25 08:33:28 EDT 1998
I have stitched together some text (below) related to a bleaching and
mortality event that resulted from extreme hot weather in the summer of
1996 in the western Arabian Gulf (western Indo-Pacific, sort of). At
the time I was impressed with the manner in which Acropora mortality
occurred. Our experience suggests that if there was 100 percent
bleaching, the result was 100 percent mortality (by tissue sloughing -
more elgantly, exfoliation) of an Acropora colony - bleached Acropora
tissues simply never recover. Now, after reading your posting, I wonder
we should not be using another term (besides bleaching) to describe the
response of Acropora to extreme temperatures.
I am not familiar with the literature on "white plague" (is that casued
by pathogens?). What is "polarized coral death" ?
Does Acropora in the Caribbean ever recover from bleaching ? I have
seen reports of Acropora bleaching in the GBR, but I do not know whether
that resulted in mortality.
King Fahd University
In the summer of 1996, nearshore seawater temperature held
between 33.5 and 37 C for approximately 90 days along
the Saudi Gulf coast and elsewhere in the Gulf (postings
to the list by Jan Corrubel, Roger Uwate, and Yusef Fadlalla)..
As a result, there was widespread multispecific bleaching in
nearshore coral communities, and an outbreak of Black Band
Disease (BBD) in the Acroporas of one reef, with catastrophic
consequences for Acropora, and Stylophora pistillata (where found).
Coral mortality followed rapidly. Acropora colonies that bleached
lost tissue in a random process, as coral tissue sloughed off
in a haphazard manner from all areas of a colony or
different locations on the same branch. In contrast, BBD affected
Acropora lost tissue as the black bands progressed in an even
pace from the bases of branches to the tips.
Both processes resulted in catastrophic losses (estimated at
over 95% of colonies of Acropora on many reefs). Stylophora
pistallata mortality was not characterized by the "tissue sloughing"
that was observed in Acropora.
Les Kaufman wrote:
> I would be very grateful if anyone could bring to my attention
> of Pacific acroporids exhibiting conditions resembling white plague
> one with tissue exfoliation and polarized coral death) in the tropical
> Atlantic acroporids.
> Les Kaufman
> Boston University Marine Program
> Department of Biology
> Boston University
> 5 Cummington Street
> Boston, MA 02215
> e-mail: lesk at bio.bu.edu
> phone: 617-353-5560
> fax: 617-353-6340
> "I believe we are on an irreversible trend toward more freedom and
> democracy... but that could change."
> -Vice President Dan Quayle, 5/22/89
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