coral bleaching in Indian Ocean

Rupert Ormond rfgo1 at
Tue Jul 14 15:05:52 EDT 1998


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,
Biology Department,
University of York,
tel: 44-1904-432930
fax: 44-1904-432860
e-mail: rfgo1 at

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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