Tourists are being asked to remain vigilant on beaches in France and Spain after a toxic algae bloom.
Climate change has led to warmer semi-tropical seas across Europe, causing higher levels of the poisonous Ostreopsis algae, according to Spain’s Institute of Marine Sciences.
Symptoms after contact with the algae include skin irritation, gastric disorders, nausea, vomiting, and flu-like symptoms such as fever, sore throat, sneezing and runny nose.
It also infects marine fauna and has resulted in large numbers of deaths among species such as sea urchins, according to Marine Environmental Research.
“Rising water temperatures in the Mediterranean Sea will cause the spread of toxic Ostreopsis algae, which will last longer and in larger quantities, and possibly pose a threat to tourism in the future,” said Dr Elisa Berdalet, from the Institute of Sciences Sea
The presence of Ostreopsis has been recorded on the Mediterranean coast for about 15 years but more recently on the French and Basque coasts.
It was first seen in the Atlantic Ocean in 2021 and since then, the “blooms” of microscopic algae have caused almost 900 poisonings along the surrounding Basque coast.
The findings come from a report by the French Agency for Food, Environmental and Occupational Health and Safety (ANSES), released in May.
In the 40-page document, Director General Benoît Vallet warns of the dangers of human contact with the algae and its toxins.
“These microalgae can cause human poisoning when the cells or toxins they produce are present in seawater, aerosols or in certain seafood,” he writes.
Ostreopsis can release fumes that remain in the air and can attack the lungs or cause other health problems if inhaled.
Those at risk include tourists, fishermen and beach cleaners as well as those who stay close to the sea and those who have eaten contaminated seafood, ANSES said in its report.
“People with respiratory problems are most at risk of showing symptoms,” said Carole Catastini, who coordinated the research. “They have to avoid the coast when Ostreopsis is in bloom.”
To protect the health of professionals and tourists visiting French beaches in the affected areas, the health agency has proposed a decision tree for local authorities and health agencies.
The proposed measures include notifying the public when there is algae in the water and preventing water activities and closing beaches.
The French health agency has also called for further research into the spread of Ostreopsis and the potential threat it poses to humans and marine life.
Ostreopsis came to Europe in the 1990s and has spread along the coast in recent years.
It can now be found on almost every Spanish beach, either in the water, clinging to rocks or even sand.
ANSES raised the alarm about the creeping threat when they reported an outbreak in the city of Biarritz, on the west coast.
Swimmers, surfers and other beach users have reported nausea, fatigue and infected eyes.
Now he is warning holidaymakers to be aware of outbreaks, and the possibility that local officials will close beaches during peak infection times in the summer.
This is not the first time that France has imposed a ban due to toxic algae. Warnings were put in place along the Cote d’Azur in 2009 when swimming was banned.
To date, large numbers of the species have been detected in the Atlantic as well as parts of the Portuguese Algarve and the Cantabrian Sea.
Rare cases of food poisoning have been reported outside Europe, by individuals who ate infected seafood, but the link to Ostreopsis remains uncertain.
As a precaution, ANSES recommends not collecting shellfish or other seafood when an Ostreopsis bloom occurs.
“Fish must be gutted before eating, as the toxins accumulate in the digestive tract,” said Nathalie Arnich, who also coordinated the expert research.