Status of Coral Reefs of the World 2000

Status of Coral Reefs of the World: 2000
although they survived the Gulf War oil spill and are dominated by massive Porites,
Montipora and Platygyra.
At least 35 coral species are found on Kuwaiti reefs along with conspicuous sea urchins
(Echinometra mathaei and Diadema setosum), which occur in dense populations (20-80 per
m 2 ) on many reefs. There are 124 fish species with the damselfish the most abundant, and
hawksbill (Eretmochelys imbricata) and green turtles (Chelonia mydas) nest on the coral cays.
Threats to coral reefs include damage from fishing and anchors, flipper damage from
divers, over-fishing, lost fishing gear, solid waste disposal, and the extreme environmental
conditions. Most of the reefs are close to the shore and are major tourist and fishing areas.
Anchors have destroyed large tracts of the reefs at all sites, and over-fishing has reduced
populations of large predators, such that few fish greater than 20cm are seen. Oil pollution,
however, has not caused massive mortalities to reefs, even though most were in the path of
the massive oil spill during the Gulf War.
Oman
Seawater temperature is the major factor controlling the distribution of coral reefs in the
northern Arabian Sea and Gulf of Oman. There are major temperature differences between
the Gulf of Oman and the northern Arabian Sea during the summer southwest monsoon
season, which show up in the nature and distribution of coral communities in Oman. Wind
is the other factor influencing upwellings, which result in temperatures changing by as
much as 8ºC in 2 hours down to 10m depth. Such upwellings in the northern Arabian Sea
result in seawater temperatures being around 19 o C throughout summer.
There were 2 significant bleaching events during the past 10 years: in the summer of 1990 in
the Gulf of Oman, seawater temperatures reached 39 o C for several days; in May 1998 at
Dhofhar, temperatures reached 30 o C. Solar radiation during the monsoon (June-September
1998) was 170-180% higher than average because of low cloud density and thinner fog
normally associated with the upwelling (all suggest a weak upwelling during that monsoon
season). Between 75% and 95% of Stylophora colonies bleached and 50% of large Porites
colonies were partially bleached in water less than 5m on the Marbat peninsula, Arabian
Sea in May 1998. Other genera were also affected. Mortality was estimated to be around
5%, and temperatures were 29.5 and 31.5 o C, but 50km to the east no bleaching was
observed at temperatures between 25 and 25.5 o C. No bleaching was observed or
reported in the Muscat Area in the Gulf of Oman (23 o 37N; 58 o 35E; temperatures to 30.5 o C).
Bleaching in Dhofar occurred in May immediately before the summer monsoon upwelling.
After the upwelling in September 1999, only dead corals covered in algae were observed
indicating almost 100% mortality from bleaching in very shallow (2-3m) waters. Corals in
deeper water appeared unaffected with low levels of mortality. On the southwest tip of
Masirah Island and southeast corner of the reef complex around Barr Al Hickman there was
little or no mortality during 1998. No bleaching was seen in Hallaniyat Islands from
February-April 1998 and corals around the islands of Al Hallaniyah, A’Sawda, and Al
Qibliah were healthy in January 2000, with high coral cover and very large (5m diameter)
tables of Acropora clathrata and Porites colonies greater than 4m in diameter.
60