It lay about seven miles (11 km) south of the mouth of the St Lucia estuary.

"Estuaries are the most dynamic of all ecosystems, and the introduction of oil would have a very adverse effect," said Richard Penn-Sawers, conservation manager at the World Heritage St Lucia Wetlands Park.

He told Reuters that workers had to prevent oil getting into the protected area at all costs, or face a possible disaster.

Tourism operators also fear a heavy spill of oil could clog up the area's pristine beaches and damage their businesses.

While a salvage team prepared to try and refloat the ship, waves washed thin lines of thick brown heavy fuel oil onto the white sands, stretching for about one km, although a northerly wind had so far helped keep the oil from the wetlands.

Mangrove swamps breath air through their roots, and a slick covering them would not only suffocate the trees, but also kill off a whole host of other fishes, birds, insects and plants that live amongst the mangrove roots.

"We are throwing in every resource we have got to keep the oil out of the estuary," Penn-Sawers said.

He motioned down to the beach where bulldozers had thrown up walls of sand to keep the tide from washing any oil up over the shallow sand bank that separates the wetlands from the sea.

ENDANGERED TURTLES MAY BE AFFECTED

The St Lucia Wetland Park is recognised as an internationally important wildlife site by the United Nations.

The park's marine conservation area is a nesting site for endangered Leatherback turtles, while reefs off the coastline are popular among scuba divers for their wide variety of fish.

The threat to the turtles is not immediate because they will not arrive for a few weeks, but if the beach is still draped in oil it could cause havoc when they try to lay eggs in the sand.

But hippopotamuses, crocodiles, wading birds and pelicans all depend on the estuarine ecosystem, just in from the coastline.

Locals have seen dolphins swimming in the oil slick at sea, and whales are due to begin a southern migration in a few weeks that will pass the accident site only a few miles offshore.

"The different ecosystems here are all dependant on each other. Destroy one and the whole lot goes," Penn-Sawers said.

The potential disaster was on everyone's lips in St Lucia.

Some entrepreneurs managed to take advantage. One sign outside a St Lucia Fishing shop read "Wreck trip - a must see".