Image credit: Hans Hillewaert

A surge in the number of jellyfish in the Mediterranean poses a threat to the environment and the health of summer tourists, scientists have claimed.

Experts also say the socio-economic impact on tourist areas would be massive, causing millions of euros to be lost.

A project working to track the rise in the number of jellyfish said they were able to prosper thanks to global warming and overfishing, The Guardian reports.

Professor Stefano Piraino, of Salento University in southern Italy, said: “I flew along a 300km stretch of coastline on April 21 and saw millions of jellyfish.”

“There are now beaches on the island of Lampedusa, which receives 300,000 tourists a year, where people can only swim for a week in the summer,” said Piraino.

‘Citizen scientists’ have been tasked with tracking the movements of jellyfish along thousands of miles of Mediterranean coastline armed with a special app on smartphones.

Other affected coastlines include Sardinia, Sicily, Malta and the eastern Mediterranean beaches of Israel and the Lebanon.

Piraino said at least 150,000 people were treated for jellyfish stings around the Mediterranean each summer.

The Institute of Marine Sciences in Barcelona has detected a surge this spring in one of the post poisonous species, the mauve stinger or Pelagia noctiluca (pictured), along the coastline at Caralonia and Valencia.

Josep María Gili, a veteran jellyfish researcher at the institute, said: “It is a growing problem in the Mediterranean, as it is in the rest of the world. But the problem is at its greatest in the open sea.”

Gili said it was surprising that mauve stringers had been found so close to beaches, adding: “Normally, that size of jellyfish does not reach the coast because of the temperature of the water.”

“The jellyfish that we see on the beach is really the sea sending us a message in a bottle, saying: ‘Look what is happening to me,'” Gili said.

“The socio-economic impact on tourist areas is huge,” Piraino said. “We are losing millions of euros.”

Beaches in Catalonia are rarely affected for more than 15 days each summer, but some Mediterranean resorts are now considering using two-metre-deep nets to fence off safe zones for bathers.

The best form of protection against jellyfish stings is suncream, preventing the venom released from penetrating the skin.