#Status of Coral Reefs 2002 - International Coral Reef Action Network

Status of Coral Reefs in South Asia
Chagos
These reefs have among the highest species diversity of corals and molluscs in the Indian
Ocean. There are several comprehensive studies on reef fish and other invertebrates, and
reef-building corals have been relatively well studied. The smaller islands support large
colonies of sea birds, sea turtles and 2 species of small cetaceans. Several of the uninhabited
islands and surrounding reefs have a Strict Conservation status, while much of Diego
Garcia is now a Ramsar site. Corals around Chagos were seriously affected by the bleaching
event in 1998. Before this bleaching event, there was 50-70% live coral cover, 10-20% soft
coral cover and approximately 10-20% bare substrate. However, after 1998, most of the live
coral cover on the outer reefs was killed, including almost all of the table corals. Soft corals,
fire coral (Millepora sp.) and blue coral (Heliopora caerulea) were also heavily impacted,
while large Porites colonies on the outer slopes were only partially bleached, and calcareous
algal ridges around the atolls appear to have been reduced. The corals in the reef lagoons
survived better than those on the outer reefs, probably because they normally experience
higher temperatures and have built up tolerance to temperature increases.
India
Biodiversity on the reefs in the Gulf of Mannar includes 94 hard coral species, with the
most common being Acropora, Montipora and Porites. The 1998 bleaching event
destroyed most shallow water corals and live coral cover was reduced by over two thirds,
such that about 25% of live corals remain. The most affected were branching Acropora
and Pocillopora. Massive corals now dominate on all island groups, with branching corals
almost wiped out in the Tuticorin group, while only 1-2% survive on the other islands.
Some patchy coral recruitment was seen on the mainland coast by the Zoological Survey
of India, in 1999. There has been a further reduction in the live coral cover with more
bleaching in early 2002 in shallow areas. Bleaching also affected many massive corals, but
most have since recovered. There is now an average of 19.5% live coral cover on the 7
islands of the Mandapam group (dead coral 21.4%; sand and rubble 53.4%). Reef fish
diversity and abundance has not been well documented.
The Andaman and Nicobar Islands have about 12,000km 2 of reef lagoons, coral banks, reef
slopes and reef flat areas. North and South Andamans are dominated by Porites, while the
Middle Andamans and Nicobars are dominated by Acropora. In all, 203 hard coral species
occur on the islands such that coral diversity is much higher than reported previously. In
the last ‘Status’ report, nearly 80% of the reefs in the Andaman and Nicobar groups were
reported as being bleached, however recent surveys indicate that 56% of corals remain
alive, with 20% dead coral and 11% coral rubble. There is no evidence of recent bleaching
or damage caused by Acanthaster planci.
The highest live coral cover on the Nicobar Islands is 73.5% on North Reef, and cover in
Car Nicobar and Outram are 72.7% and 67.3% respectively. These numbers, and the
continued dominance of Acropora on the Middle Andamans and Nicobars, indicate that
there has been no recent bleaching mortality. More than 1200 fish species have been
recorded around the Andamans and Nicobars. Sponges, sharks, spiny lobsters, dugongs,
dolphins and sea turtles are also exploited in the islands.
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