Channel Island’s authorities considering measures to protect people from coastal algae linked to death of jogger in France

Authorities in the Channel Islands are looking at ways to protect residents and visitors from toxic beach gases after the death of a jogger in France that has been linked to the fumes from rotting seaweed.

The government of Jersey said on Monday it was considering the installation of devices to check gas levels from deposits of sea lettuce. Warning signs could also be erected on affected coastlines to tell people of the potential danger posed by rotting green algae.

Jean-René Auffray collapsed while jogging at a river estuary in Brittany, about 50 miles south-west of Jersey. French authorities concluded he died of a heart attack. But they are exploring the theory that he may have been overcome by sea lettuce fumes, following pressure from environment experts.

Facebook Twitter Pinterest Sea lettuce exposed at low tide in Swanage, Dorset. Photograph: FLPA/Alamy

Gas from decomposing sea lettuce in northern France has been linked to the deaths of wild boars in 2011 and a horse in 2009.

St Aubin’s Bay in Jersey often has sea lettuce infestations. The island’s government, the States of Jersey, said it would monitor the situation and could introduce safety measures, but does not believe people are currently at risk.

The infrastructure minister, Eddie Noel, said the quantity of sea lettuce on Jersey were not at the same level as in France and elsewhere in the world.

“The levels are monitored and if there were to be any buildup, action would be taken to protect public safety,” he said, adding that heavy deposits of rotting sea lettuce – Ulva lactuca – may produce gases, including hydrogen sulphide.

Noel said contractors removed the algae for the Jersey government last summer and trialled the use of gas monitors, which were not activated.

But he said: “A review of operations for the 2017 summer season will include considering greater use of these monitors and possible public safety signage in extreme conditions to warn of the risk, however small, of walking, jogging or exercising dogs in heavily affected areas.”

Noel said it was unreasonable to connect Auffray’s death with the sea lettuce at St Aubin’s Bay and doing so could harm tourism on the island.

Auffray’s death has focused attention on what causes Jersey’s sea lettuce growth, which Noel said was owing to “several elements”. It tends to proliferate in warm, clear, calm, nitrate-rich waters. St Aubin’s Bay is a perfect breeding ground because of its position– it is sheltered and sandy – and because it is rich in nitrates washed from farms in Jersey and northern France, and from the Bellozanne sewage treatment works.

Jersey’s government stressed that the sea lettuce problem was not unique to the island: there have been blooms in Kent, Ireland, Portugal and Italy, commonly in bays with similar features to St Aubin’s.

Possible solutions for the problem include towing it out to sea and dumping it, and the introduction of oysters that feed on nitrates.

The campaign group Save Our Shoreline Jersey (SOSJ) said there was no doubt that sea lettuce released sulphurous gases. “These ‘rotten egg’ smells mean local residents have to shut their windows in hot weather, tourists and locals complain, and seaside cafes suffer from a marked decrease in custom,” the group said.

“Bouncing on the piles of dried lettuce runs the risk of toxic gas escaping, so we recommend small children and dogs are kept from [doing so because] they are much closer to the ground and could be affected before the wind disperses the gas.”



SOSJ said hundreds of tonnes of fertiliser was being used by farms growing Jersey Royal potatoes, and that the island’s growing population was creating more sewage.

Jacqui Carrel, an environmental scientist for SOSJ, said the group had suggested measures such as ploughing shallow furrows at angles to the sea in these areas, dislodging the weed before it takes root. “[But] successive governments have said there is nothing they can do.”