"Healthy ecosystems can save lives," said WWF Asia-Pacific director Isabelle Louis.

"Places that had healthy coral reefs and intact mangroves, which act as natural buffers, were less badly hit by the tsunami than those where the reefs had been damaged and mangroves ripped out and replaced by prawn farms and poorly planned beachfront hotels," she added in a statement.

WWF said once immediate humanitarian and health needs were met, reconstruction should involve environmentally-sustainable coastal planning, such as not building within a safety zone delimited by the high-tide mark.

It should also "capitalise on natural defence mechanisms" to make sure that coral reefs, mangroves, marshes, and forests that buffer the impact of tidal waves are restored or protected.

The appeal came as a United Nations conference on small island nations -- including the Maldives, one of the countries struck by the catastrophe in the Indian Ocean -- was due to open in Mauritius Monday.

The damage from the tsunami could have been much worse in the Maldives if the government's attempts to protect coral reefs that shield the islands from the open sea "had not been so diligent", according to WWF.

Sri Lanka's government said last week that it would enforce strict laws to avoid future disasters when it rebuilds its shattered coastline.

Measures would include a ban on building new tourist hotels on the seafront and a clampdown on illegal shacks and houses which had sprouted on the palm-clad beaches, officials said.

WWF also called for urgent help to rebuild small local fisheries, the primary livelihood for thousands of communities affected by the tsunami.

"Opportunistic" industrial-scale fishing fleets based elsewhere could move into regional waters, depleting fish stocks and compounding the plight of local communities around the Indian Ocean, it warned.

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