A potentially toxic seaweed originally found off Japan has colonised a stretch of the Mediterranean coast near Marseille that is home to one of France's most popular natural attractions.

The green algae, rugulopteryx okamurae, poses a health risk because once it washes up on rocks and beaches it begins to decompose and emit hydrogen sulfide, a putrid gas that can be lethal in large doses.

In recent weeks the plant has "proven to be invasive" at the wildly popular Calanques National Park, whose secluded beaches tucked in narrow, steep-walled inlets draw thousands of people every day in the high season, a spokesman told AFP.

It has also been spotted on wharfs in Marseille and to the west of the city along what is known as the Cote Bleue.

"It spreads and stinks up everything, the smell is nauseating," said Guy Coulet, a Marseille resident.

The weed is even more prolific in the shallow waters off the coast, he said, where it "is a real problem for fishing boats, clogging up their nets."

Thierry Thibault, a researcher at the Mediterranean Institute of Oceanography, said the algae has been present in the Thau Bassin, around 200 kilometres west of Marseille, since 2008.

It was probably spread by "someone who ate sea urchins from the Thau Bassin... and threw the shells back into the sea," he said.

Marseille officials say the situation is under control and analyses are underway to determine how best to eradicate the seaweed.

"At this point there is no danger for humans, but if the gas concentrations get too high we'll have to close beaches," said Herve Menchon, a deputy mayor in charge of marine biodiversity.

He acknowledged, however, that children swimming in the port -- in theory prohibited -- "is a problem," and officials have stepped up measures to keep people out.

Regional authorities have also been pulling out dense piles of the algae that form underwater, but for now there is no solution on what to do with the reeking plants as they rot.

Related Links
Water News - Science, Technology and Politics

Tweet

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

Coastal cities face their mortality on the climate 'frontline'
Paris (AFP) June 23, 2021
For thousands of years, people have built their great metropolises right up against the contours of coasts, in estuaries and deltas, confident of the ebb and flow of the tides. Domination of the seas allowed many coastal cities to become trading powerhouses and cultural melting pots. But now that strength is becoming a liability as climate change swells the oceans, redrawing the map and putting hundreds of millions at risk. That's the warning of an unpublished draft report by the UN's clim ... read more