Tsunami-hit reefs may take years to recover

The Indian Ocean tsunamis caused extensive damage to coral reefs of the Andaman and Nicobar islands, which are now smothered by sediment that will take years to wash off, scientists said on Monday.

The archipelago, which spans 800km from Indonesia to Myanmar, suffered deep damage to coral in the hard-hit south-west areas and a major shift in the geography of the islands, according to a survey prepared by Indian government scientists.

Science and Technology Minister Kapil Sibal unveiled the preliminary findings on the coral reefs from a survey by four research ships as part of an effort to understand the long-term impact of the December 26 tsunamis that killed more than 16 000 people on the islands and south Indian mainland coast.

More than 2 000 people died on the islands alone and 5 640 are still listed as missing.

"If we take Andamans as a straight line then areas east have moved westward at places by three metres maximum and certain parts have sunk by 90cm and this is permanent," said Harsh Gupta, the top bureaucrat in the Science and Technology Ministry.

Gupta, who is a seismologist by profession, warned it may take three years before geological stability comes to the archipelago which has been hit by thousands of aftershocks ranging between three and five on the Richter scale since the tsunamis.

He also said the tsunamis pushed tons of silt onto reefs in the south-west of the island chain that are home to 200 types of coral and thousands of fish species.

"The reefs north-east of Andamans are in good condition but they have been disturbed in middle and in the south," he said of the cluster of isles which bore the brunt of the tsunamis.

Other scientists fear it may not be possible to repair damage to the reefs, second in biodiversity only to Australia's Great Barrier Reef.

BR Subramonium, one of the scientists belonging to a state-organised national programme to develop a tsunami-warning system, said it would take a huge effort to clean up the smothered reefs.

"Whatever artificial objects are on the reefs can be cleared up but it would take quite a few years to remove sediment deposits from the coral. We would require long-term monitoring of this," said Subramonium of India's department of science.

The sediment blocks light from reaching the fragile coral, Subramonium said, making it difficult to sustain life or regenerate new coral.

Gupta, meanwhile, said the survey found fish catches in the worst hit south-west areas of the island chain have dropped sharply to 300kg per catch from 1 500kg before the disaster.

But that has been offset in part in the north where damage was lighter with the average catch now more than 100kg from nine kilograms earlier.

Source: www.iol.co.za