A beach in Biarritz, in southwestern France, was closed to swimming on Thursday due to a high concentration of a toxic micro-algae, which had caused a wave of panic and the closure of several Basque coast beaches in 2021.
"If the presence of the micro-algae Ostreopsis had been observed for several days but at moderate levels, its sudden intensification was likely caused by the swell that occurred at the beginning of this week," stated the Regional Health Agency (ARS) and the Basque Country Agglomeration Community in a joint statement.
Several surfers and swimmers, in particular, reported to the authorities symptoms specific to the presence of this micro-algae, which is invisible to the naked eye, but "no reports of serious cases have been received," they specified.
The Biarritz town hall announced on Thursday on its website that "swimming and water activities will be prohibited" at the Port-Vieux beach, "pending new samples."
In 2021, several hundred reports of flu-like symptoms, rhinitis, or respiratory tract irritation had alerted local officials, who were forced to close the beaches of Biarritz, Bidart, and Saint-Jean-de-Luz.
A French court in June ordered the state to compensate the family of a 50-year-old man who died in 2016 during a run after inhaling poisonous gas emitted by rotting green algae piled along the country's western coast.
French court orders state to compensate family of jogger killed by toxic algae
Ocean warming and toxic algae
Ostreopsis ovata, a toxic micro-algae well known in the Mediterranean for several years, is now established on the Basque coast, both French and Spanish. Its presence is a direct consequence of climate change and ocean warming, according to scientists.
A research program bringing together scientists and institutions from both sides of the border, in the Basque Country, was launched in April 2024.
Mediterranean Sea experienced marine heatwaves of 'record intensity'
Developed over three years at nine coastal sites, it is designed to help policymakers develop an alert protocol, or even new regulations.
There is currently no regulatory threshold for this micro-algae.
On Friday, the Biarritz town hall re-opened the beach, advising the most vulnerable people to remain vigilant.
(with newswires)
