Status of Coral Reefs of the World 2000

Status of Coral Reefs of the World: 2000
unique reef structure rising abruptly from 800m depth to form an atoll that has been
recognised as a regionally important conservation area such that it was proposed to
UNESCO for World Heritage Status in the 1980s, but there has been no follow-up.
Yemen
Most of the coral reefs occur along the Red Sea coast and the Socotra archipelago, with some
sites in the Gulf of Aden. Corals grow on the Red Sea coast as both coral reefs and coral
communities on a variety of substrates. Coral reefs in the northern Gulf of Aden are limited by
intense cold seasonal upwelling. Extensive coral reefs surround the Socotra archipelago.
STATUS OF CORAL REEF BENTHOS
There were many surveys and studies on coral reef communities between 1997 and 2000 in
this region, including some that updated information collected previously, to allow
comparisons over time at key locations. In some countries, these involved rapid
assessments of coral reef habitats, with the most common methods being: belt transects for
fish census, line intercept transects for substrate cover and composition, and timed swims
for assessment of general reef condition and major disturbances. In Saudi Arabia and
Yemen, satellite imagery was used to document the extent of reef habitats. Wide
differences in the number of hard coral species were reported for the different countries,
generally reflecting variance in the intensity and method of examination, rather than real
differences. For example, the largest number of coral species have been reported in Saudi
Arabia, where there has been a major effort to assess Red Sea reefs.
Coral cover on Red Sea reefs is generally high, in particular along the fringing reefs and
offshore islands and barrier reefs. In the Gulf of Aden coral growth is limited by the
seasonal upwelling of colder water, and reefs are patchily distributed, while reefs
surrounding Socotra have an unusually high cover. Most areas of the Gulf of Aden and
Socotra do not have true growing reefs, but some sites have live coral cover of over 50%,
with very large colonies growing on rocky bases. Around Socotra, hard coral cover ranged
from 1% to 75%, and there were some large patches (e.g. 1,000m 2 ) with about 100%
cover. Overall, living hard coral cover averaged 20%, with highest cover (35%) on the
Brothers (Samha, Darsa and including Sabunyah) Rocks, and on the north coasts (25%) as
compared to 5% the south coasts. The following provides a synopsis of coral cover and
health for each country based on recent surveys. (Results related to fish communities and
links with respective fisheries are reviewed subsequently).
Djibouti
Two brief, but extensive, reef assessments were conducted in 1998, followed by a more
comprehensive survey in 1999. These provided the first detailed information on the coral
reefs, showing that there were 167 coral species dominated by Acropora hemprichi,
Echinophora fruticulosa and Porites nodifera. Only 10% of the species were found at all
sites, 40% were observed at several sites, and approximately 50% were found at only a
few sites. Acropora spp. suffered high mortality in Khor Ambado and off Maskali.
Percentage cover ranged from 5% (off the main tourism beach on Maskali) to 90% (at
Hamra Island, Sept Freres), where the dominant Acropora formed coral gardens. However,
the diversity was highest at Arta Plage, then Grande Isl. (in Sept Freres), and then Trois
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