coral bleaching in Indian Ocean
rfgo1 at york.ac.uk
Tue Jul 14 15:05:52 EDT 1998
INCREASED CORAL BLEACHING IN THE RED SEA AND INDIAN OCEAN 1997-8
Joyce Hsieh and I would like to thank all coral-listers who responded with
information about recent bleaching in the Indian Ocean and Red Sea to our request
posted on the coral-list earlier this year. We have been shocked by the extent of
the bleaching revealed from this and other survey work. We have prepared a
report based on these data, and for those interested a copy is attached (minus
figures) as a Word 6 file. An abstract of the report is given below.
We would welcome comment and further information prior to publication.
Dr. Rupert Ormond
Senior Lecturer & Director,
Tropical Marine Research Unit,
University of York,
YORK YO1 5DD U.K.
e-mail: rfgo1 at york.ac.uk
Abstract. Coral bleaching) resulting in extensive coral mortality has been reported
with increasing frequency over the last 15-20 years mainly from Caribbean and
Pacific Oceans. This bleaching has been found to be associated with above
normal maximum surface seawater temperatures (SSTs) typically linked to El Niño
/ Southern Oscillation (ENSO) events. Until now significant bleaching has rarely
been reported from Indian Ocean or Red Sea, but during 1997-8 we received
word-of-mouth reports from divers that bleaching might be occurring on an
unprecedented scale in this region. We therefore circulated government agencies,
dive centres etc. with an information leaflet and request for information. Over 20
positive reports were received of bleaching in 12 different countries. These
indicate that significant bleaching occurred in the central Arabian Gulf during 1995
and 1996, and in the central and southern Red Sea in the summer of 1997.
Bleaching also occurred in the Maldives in mid-1997, and again in early 1998,
since when bleaching has also occurred over a large part of the Western Indian
Ocean, including the Seychelles, La Reunion, Comoros and East Africa. We found
that in almost all cases bleaching was associated with SSTs, as recorded either in
situ and / or derived from satellite data, that were significantly above the normal
maxima for each area. The higher than normal SSTs during 1997/8 appear linked to
the recent El Niño (ENSO) event which has recently been confirmed to influence
Indian as well as Pacific Oceans.
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