The wreck of the Costa Concordia cruise ship with 2,380 tonnes of fuel on board is threatening the environment of the Italian island of Giglio in Europe's biggest marine sanctuary.
"The effects would be devastating" if fuel from the ship which crashed onto the island last Friday leaked into the Mediterranean, Sebastiano Venneri, head of marine work for the Italian environmental group Legambiente, told AFP.
"The impact on the flora and fauna would be major and immediate," he said.
He added that the fuel in the ship's tanks was "a low quality product with a large quantity of tar," which would kill all life around it.
"If the accident had happened hundreds of kilometres (miles) from the shore in an area where the depth was 700 or 800 metres (2,300-2,600 feet) the impact would have been less serious because there is no photosynthesis at that depth," he said.
"But this area near the coast is much more fragile, more sensitive."
The island of Giglio is part of the Tuscan Archipelago National Park, which says it is Europe's biggest marine sanctuary with a protected area fo 56,800 hectares (140,0400 acres) of sea and 17,900 hectares of land.
The park has many endemic species including molluscs, butterflies and lizards and is a a place where migratory birds make their nests.
It is made up of seven islands: Capraia, Elba, Giannutri, Gorgona, Montecristo, Pianosa and Giglio, which has an area of 23 square kilometres (nine square miles).
The deepest waters around Giglio are rich in fish including tuna that can reach more than three metres in length as well as barracudas. The underwater rocks contain a wealth of moray, crayfish and giant mussels and crabs.
In spring and summer, dolphins and whales can be seen off the island.
The park's administration is taking the wreck very seriously saying all of its members were "on alert to understand in real times the best moves to take and any possible form of collaboration."
"The risk of environmental damage to the archipelago's seas has not yet receded but there is maximum attention that nothing happen and our assets in the field are extraordinary," it said.
The director of the park, Angelo Banfi, said: "There is a lot of concern for our island of Giglio but no alarmism. We are doing what we can."
He also said the government should impose new rules on shipping routes "to ensure that the Tuscan archipelago does not run these risks."
Angelo Gentili, a director of Legambiente who hails from the Tuscan town of Grosseto near the island, said: "It's a very delicate ecosystem with many varieties of fish and seaweed that are very rich in terms of biodiversity."
Gentili said that the recent wreck of a ship in New Zealand polluted 20 kilometres of coastline when its 350 tonnes of fuel spilled into the sea.
"We should also remember that all the toxic products would enter through plants and micro-organisms into the food chain or would remain for years and years with very grave consequences," he said.
He added: "One cubic centimetre of fuel can pollute one cubic metre of sea water in which all life disappears."