Oil spill in Mauritius: corals and mangroves threatened in the long term

The corals of Mauritius were not directly damaged by the oil spill caused by the sinking of the bulk carrier MV Wakashio, but are threatened in the long term, as well as the mangroves, Japanese experts estimated Tuesday.

The MV Wakashio, operated by the Japanese company Mitsui OSK Lines, struck a reef on this island in the Indian Ocean on July 25. The wreckage broke in two, three weeks later, after a race against time to pump out the fuel it still contained.

The ship let out at least 1,000 tonnes of fuel oil from its sides, which soiled the coasts - including protected areas home to mangrove forests and endangered species - and the crystal clear waters that attracted many tourists before the coronavirus pandemic.

Dangerous debris

Japanese experts dispatched to the scene explained during a video conference Tuesday that they had examined a dozen underwater areas 800 meters northwest of the wreck. They did not find any damage to the seabed and their coral reefs.

The longest part of the wreckage, cleared of the oil and debris present, was sunk on Monday at great depth offshore, according to the authorities, an operation which took several days. But the rest of the ship, the stern surmounted by the superstructure, remained beached at the site of the sinking.

Japanese experts noted that tiny debris from this wreck was falling into the sea, as the whole oscillates with the waves on the reef on which the ship ran aground. "If this situation continues, it could endanger the corals and kill them," said Noriaki Sakaguchi, an ecosystem specialist with the Japan International Cooperation Agency (JICA).

Initiatives to remove particles from the bulk carrier that have fallen into the water would also risk damaging the coral, which is also damaged by the ropes of the floating barriers set up against the oil spill, he said. The only solution would therefore be to remove the remaining part of the wreckage from the reef, the Japanese experts concluded.

Cleaning, a delicate mission

Oil slicks have also reached mangroves along the coast, threatening to kill plants in these protected areas in the coming months, they also warned. Cleaning mangroves is an extremely complicated task, as working on their very loose soils risks sinking the oil even deeper. For the time being, the clean-up work is focused on recovering algae and other plants soiled by the oil spill and washed up on the beaches.

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VIDEO. Oil spill on Mauritius: "We make buoys with the hair and feathers of guinea fowl"

The circumstances of the sinking remain unclear. According to a source close to the investigation cited on Monday by the Japanese press agency Kyodo, the boat would have approached the coast of Mauritius to receive the mobile network.

A drunken birthday party would also have been held on board shortly before the accident, according to the same source, without it being known if the watch team participated. The captain of the boat, of Indian nationality, and his Sri Lankan deputy were arrested and indicted last week by the Mauritian justice.