RIVIERA tourist chiefs fear a massive invasion of stinging jellyfish on the Mediterranean coast this summer as hot weather has warmed up the sea, which encourages them to develop.
They forced tourists to flee from the beaches of Monaco, Antibes, Cannes and Nice last summer and researcher Floriane Delpy, a Phd student at the Mediterranean Oceanology Institute, says there are indications of a new influx.
She told Le Figaro "Nothing is certain at the moment, but several factors are pointing that direction."
And Lars Stemman, of Paris VI University at the Oceanological Observatory at Villefranche-sur-Mer, said there are "more and more" jellyfish in the waters since 2000.
He and other researchers at the observatory have set up Jellywatch.fr - an internet site to warn bathers of sightings of jellyfish and to show the direction of currents.
Currents are particularly important as they push the jellyfish towards the coasts - when the currents come from the east the jellyfish arrive immediately on the beaches. Similarly, when there is a strong west wind the jellyfish arrive a couple of days afterwards.
The warm sea means that the jellyfish - known as méduses - mature more quickly and reproduce quicker. Instead of a year-long cycle some are reproducing every six or eight months.
Ms Delpy said coastal pollution also played an indirect role as jellyfish live on small shellfish, which live on the algae which bloom in polluted waters.
However, industrial fishing has also meant depleted stocks of sardines, which also eat the shellfish and indirectly keep down jellyfish numbers by depriving them of food.
The purple jellyfish Pelagia Noctiluca is particularly feared as it gives a painful sting. It can grow to 40cm across. At night, the jellyfish can give off flashes of light.