HOLIDAY beaches from Rome to Genoa are deserted, despite an unrelenting heat wave, because of a plague of poisonous algae that can turn even the sea breeze toxic.

Scientists blame a rise in sea temperatures for the phenomenon, which is causing damage to tourism that could run into millions of euros.

At Fregene, the fashionable resort on the coast near Rome, normally overflowing car parks were deserted yesterday and beach umbrellas and sunbeds were stacked unused. Where holidaymakers are usually packed in rows in August, there was only hot, empty sand.

At Mastino’s, a restaurant and bathing beach favoured by rich and famous of Rome since the days of La Dolce Vita in the 1950s, the sign says “divieto di balneazione” (bathing forbidden). “This is a disaster,” said Ignazio Mastino, the lifeguard and nephew of the owner, Gillo Mastino.

Because of toxic algae, a 150km (93-mile) stretch of Lazio coast is out of bounds, from Nettuno to Ladispoli, where shoals of dead fish washed up on the beach yesterday. Local health authorities have also banned bathing further north at beaches near Genoa, after a 60-year-old man was kept in hospital and 14 bathers needed treatment.

Tests show that the culprit is Ostreopsis ovata, algae that release neurotoxins into the air. The weed usually rests on the bottom of the sea but rises to the surface when blooming.

Holidaymakers fall ill either by coming into contact with it while swimming or by inhaling toxins carried by the breeze. Symptoms include breathing difficulties, irritation to the skin and eyes, fever and coughing.

Michele Bianchi, the lifeguard at the “Hang Loose” beach at Fregene, blamed fertiliser from nearby farmland.

But Silvio Greco, a government marine scientist, said that warmer currents in the Tyrrhenian Sea were to blame. Some bathers have also been treated for jellyfish stings. Antonio Di Natale, the chief marine biologist at the Genoa Aquarium, said that the jellyfish and toxic algae were the result of warm currents from North Africa, with Italian coastal temperatures reaching nearly 30C (86F) in some cases.

“The sea is becoming feverish,” La Repubblica said. “The Mediterranean is gravely ill,” said Il Messaggero, the Rome daily. Last weekend Mario Canapini, the Mayor of Fiumicino, dived into the sea in a T-shirt saying “I Love Fregene” to show the scare was unfounded.

Traders said that they would seek damages over the crisis. Corriere della Sera, however, said beach attendances were also falling off because of “the sting of high prices”.

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