Marine Life to Recover Slowly from Tsunami

Beaches around South Asia devastated by tsunamis could be restored to their former glory within a few years, but the marine life through which the huge waves passed could take centuries to recover, experts say.

Coral reefs, mangroves, fish and other marine life had been damaged by the tsunamis which rose out of the Indian Ocean on Sunday, triggered by a massive earthquake near the Indonesian island of Sumatra.

The disaster has left more than 119,000 people dead and up to five million displaced in the region, with Indonesia, Thailand, India and Sri Lanka the worst affected countries.

"It is so hard to say in brief, but the level of devastation of coastal areas by the disaster is obvious," director of Conservation International in the Indonesian resort island of Bali, Ketut Sarjana Putra, said.

"It will take a long time to recover."

The ocean's seagrass bed and mangrove ecosystem would also be affected, Putra said, but it is the reefs that bore the brunt of the destruction.

"The coral reef system might be totally destroyed. It will take hundreds of years to grow back," he said.

The health of the reefs could in turn dramatically affect the size of fish populations which rely on them for their habitat.

Lyle Vail, director of the Lizard Island Research Station on Australia's Great Barrier Reef, said damage to coral reefs from a tsunami would likely be similar to that from a cyclone.

When a tsunami passes, reef structures grind into each other causing extensive damage. In serious cases recovery would be slow as there would be fewer larval animals to repopulate the coral.

A major problem would be a loss of fish, displaced by the waves from their habitat, and other forms of protein which depend on the reefs.

Regional marine programme co-ordinator for South and Southeast Asia with the IUCN (World Conservation Union) in Colombo, Sri Lanka, Jerker Tamelander, said damage to the marine ecosystem could be "very, very serious."

"You have a region where the marine ecosystem is stressed and degraded as it is," he told AFP.

Tamelander said many coral reefs in the Indian Ocean were just beginning to recover from damage caused by the changing water temperatures generated by the El Nino weather pattern.

"In the region as a whole I think we can expect very severe ecosystem effects," he said, adding the recovery process for coral reefs could take "decades to centuries".

A major problem would be the amount of silt, sand and organic matter churned into the water which would then "smother" vegetation and marine life. Coral could also have been damaged by exposure to the air as water was sucked back from the shore before the tsunamis hit.

Tamelander says in some cases mangroves, which protect the shore from erosion and often serve as nurseries for young fish, would also have been completely uprooted and destroyed.

"There will be ramifications over the coming years," such as shoreline change, he says.

Michael Keough, professor of marine ecology at the University of Melbourne, said while relatively little research has been done on the impact of tsunamis on reefs, clearly the damage was potentially very serious.

Thailand, India, Sri Lanka, Indonesia and the Maldives all have extensive reef systems in the affected areas, he said.

"It is difficult to tell just how far offshore the damage extends," he said.

A tsunami passes more quickly than a cyclone but it may have more power which would intensify as it entered shallower water, where the coral reefs grow.

Apart from the reefs, many of the affected areas also have fish farming operations near the shore which would have been inundated.

It was difficult to predict how long recovery would take, Keough said.

"In cases of severe damage there are cases where you do not see much recovery after 30 years," he said.