Status of Coral Reefs of the World 2000

Status of Coral Reefs in South Asia
old limestone, sandstone and rocky reefs, with the location of reefs well known, but poorly
mapped. Reefs are important for fisheries, coastal tourism, and preventing coastal erosion.
CORAL REEF STATUS AND BIODIVERSITY
Bangladesh
Coral communities extend to about 200m offshore of St. Martin’s Island with maximum
coral cover of 7.6% and colony density of 1.3m -2 . These comprise 66 hard coral species,
the most common are Porites, Acropora, Favites, Goniopora, Cyphastrea and Goniastrea.
Acropora spp. are the target for coral harvesters, as well as Favites and Goniastrea. There are
also many soft corals, sea fans, and sea whips. Other invertebrates are only represented by
a few, with molluscs being the most abundant large invertebrates, however, these are
declining due to unregulated harvesting. Reef fish diversity is low (86 species) with
damselfish (Pomacentridae), surgeonfish (Acanthuridae) and parrotfish (Scaridae) being the
most abundant. There are also 5 species of butterflyfish (Chaetodontidae) and one
angelfish (Pomacanthus annularis). Predator species (groupers, snappers, and emperors) are
heavily fished. There are no reports of coral bleaching from St. Martin’s Island.
Chagos
These reefs have the highest species diversity of corals and molluscs in the Indian Ocean.
There are no comprehensive studies on reef fish and other invertebrates, yet reef-building
corals have been relatively well studied. The smaller islands support large colonies of sea
birds, sea turtles and many species of small cetaceans. Formal protection for the Chagos
reefs has been proposed. Corals around Chagos were seriously affected by the bleaching
event in 1998. Before this bleaching event seaward reef status included: 50%-70% live
coral cover, 10%-20% soft corals and approximately 10-20% bare substrate.
Approximately 55% of the live coral cover on the outer reefs was lost after the bleaching,
including most of the table corals. Soft corals, fire coral (Millepora sp.) and blue coral
(Heliopora caerulea) were also heavily impacted during the 1998 event, while large Porites
colonies on the outer slopes were only partially bleached, and calcareous algal ridges
around the atolls were unaffected. The corals in the reef lagoons survived better than those
on the outer reefs, potentially because they normally experience higher temperatures and
have built up tolerance to temperature increases. (see Bleaching Chapter 2).
India
In the Gulf of Mannar, approximately 3,600 species have been recorded within the three
main ecosystems (coral reefs, mangroves and sea grass beds) in the Gulf of Mannar.
Biodiversity on the reefs include 117 hard coral species, with the most common corals
being Acropora, Montipora and Porites. Other resources in the area include sacred sharks,
pearl oysters, sea turtles, dugongs and dolphins. The main seaweeds are Gracilaria,
Gelidiella, Hypnea, Sarconema, Hydrodathrus, Caulerpa, Sargassum and Turbinaria. Reef fish
diversity and abundance has not been well documented. The bleaching event in 1998
destroyed most shallow water corals in the Gulf of Mannar, with live coral cover reduced
by 60-80% and only about 25% of live corals remaining. The most affected species were
the branching Acropora spp. and Pocillopora spp. All the Montipora spp. on Pullivasal
Island (northeast Gulf of Mannar) were bleached during 1998 (although Montipora
aequituberculata escaped bleaching in southern Sri Lanka). Massive corals are now
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