Bleaching in the Gulf of Oman
michelc at squ.edu.om
Tue Sep 24 01:35:48 EDT 2002
BLEACHING: RECENT EVENTS AND RECOVERY FOLLOWING THE 1998 EVENT
A bleaching hot spot alert was posted on the coral list at the beginning of
July when a pool of water 2C above the long-term monthly average was
centred near Muscat. Subsequently, some paling of Goniopora colonies was
reported by divers at the Daymaniyat National Nature Reserve, 40km off the
coast of Muscat in early August that had worsened by late August.
Observations at Kharabah Island (Most eastern Daymaniyat Island) made in
late August showed that the most affected corals were in water less than 6m
depth. The most severely affected species were Astreopora (100% of colonies
totally bleached), Symphyllia recta (60-70%), Goniopora species (50%),
Platygyra (20% of colonies partially bleached), and soft corals (25% of
colonies bleached). Together the hard coral species make up a coral cover of
20% out of a total hard coral cover of approximately 85%.
Coral communities in deeper water, 6-20m appeared unaffected.
Corals along the mainland coast of Muscat appear also to be largely
unaffected, and intermittent monitoring for bleached corals continues.
The bleaching event that occurred in southern Oman in 1998 only affected
very shallow corals along a relatively short stretch of coast near Mirbat,
and had a minor impact on the marine ecosystem there. A survey in several
coral-rich coves in January 2002 (5-10% coral cover) showed that hard coral
cover had fallen compared to observations made in 1996 (20-30% cover). The
decline cannot be solely attributable to the effects of bleaching in 1998
but is more likely to be the result of a range of natural factors including
the natural stress associated with summer upwellings, COTS, etc as well as
the effects of abalone fishing and SCUBA diving activity. The density of
coral recruits was low compared to other sites in Southern Arabia (e.g.
Socotra), indicating that recovery will be slow.
Michel Claereboudt and Simon Wilson
Sultan Qaboos University
College of Agricultural and Marine Sciences (BOX 34)
Dpt. Marine Science and Fisheries
Sultanate of Oman
Tel (968) 515 249
Fax (968) 513 418
Email; michelc at squ.edu.om
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