Tsunami: coral reefs can recover quickly

http://www.hindu.com/seta/2006/01/05/stories/2006010500031600.htm



IN THE aftermath of last year's cataclysmic tsunami, Dr. Gregory Stone of the
New England Aquarium co-led an expedition to survey the damage caused to
Thailand's coral reefs.

As reported in a recently released technical report available on the New England
Aquarium website and in December's issue of National Geographic, the
expedition's results indicate a quick recovery for most of the reefs.

These affected coral reefs are a critical resource for millions of people in
that region as they are invaluable for their biological diversity.

Important role


The dive tourism industry is a major part of the region's economy and locally
caught fish are a primary source of protein in the diet of the people in the
region. The coral reefs there are among the most beautiful in the world.

An international team of eight scientist-divers, led by Dr. Gregory Stone of
Boston and Dr. Gerald Allen of Australia, travelled to the coast of Thailand
approximately three and a half months after the tsunami struck in order to
rapidly assess the extent of damage to reefs.

After more than 500 dives at 56 sites, though the team found plenty of damage,
there appears to be reason for optimism. Of the reefs assessed, 36 per cent
showed very little to no damage, while 50 per cent showed a moderate amount of
tsunami-related damage. Only 14 per cent of the surveyed reefs had suffered
severe damage.

And near the earthquake's epicentre off Indonesia - far from the survey - the
seafloor was heaved up by an estimated 16 feet , lifting some coral clear out of
the water.

Large bays, which can intensify the waves, were hit especially hard, with table
corals big enough for a family dinner scattered and broken, and massive coral
heads toppled and smothered in silt.

It was discovered that the damage to reefs varied with water depth and local
geography. To deep-water reefs in the open ocean, the tsunami posed little
threat, where its fast-moving waves were only a few feet tall.

In large, shallow bays, the most damage was suffered, where the strength of the
waves was amplified. Coastal development often worsened the damage. It was found
that pounding of the reefs by debris added to the devastation.

There is some good news. The vibrant and diverse habitats typical of the region
- the reefs - are expected to recover quickly.

Recolonisation by larvae


According to fish expert Gerry Allen of the Western Australian Museum, there are
still plenty of fish around in the reefs. Damaged coral formations can continue
to grow, and even dead reefs may, in time, be recolonised by coral larvae.

The scientific team concluded that the rare devastation of the tsunami was less
of a long-term threat to the coral reefs than ongoing human-caused damage such
as over-fishing, poorly planned coastal development and global warming. - Our
Bureau


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