French beach sees rise in stranded compass jellyfish

Compass jellyfish are known as such due to the distinctive geometric markings on their bodies

A beach in France has reported a noticeable rise in large “compass” jellyfish beached on its sand, as temperatures continue to soar across the country.

The beach at Brétignolles-sur-Mer (Vendée, Pays de la Loire) is now host to a large number of jellyfish (chrysaora hysoscella). They can measure 30-60cm in diameter, and weigh as much as 50 kilos each, and are dubbed “compass jellyfish” due to their brown geometric markings.

Unfortunately, if they become stranded or beached, they may die, requiring help from local services to clear them. In April 2017, four tonnes of jellyfish were reportedly picked up from the beaches of Olonne-sur-Mer, along 2km of coastline.

In hot and sunny weather, they tend to come into shallower water, as their main source of food - plankton - multiply and gather near coastlines. They can then be blown further up the beach by the wind and sea currents.

Stéphane Auffret, director of the Océarium in Croisic, told news network France 3: “It is a known phenomenon; stronger sunlight creates more plankton, so therefore more food in the water. [But] they are also drifting animals, and the wind and currents can move them.”

The first jellyfish of the year are born in March-April time, and begin to appear in the sea in spring and early summer.

Mr Auffret said: “The more heat, the more food; and the stronger the sunshine, the more the jellyfish will grow. But it is still wind and currents that will transport them [furthest].”

The animals are also seen regularly at the Saint-Brévin beach in the Loire-Atlantique (Pays de la Loire).

Visitors to affected beaches are warned not to approach or touch the jellyfish on the sand or in the shallow water, as the animals may be dead, but could still sting due to the stinging cells remaining on their bodies.

If you are stung or touched by a jellyfish, you should wash the affected area with salty sea water. Using freshwater will actually increase the irritation, according to a warning from the health ministry.

If any tentacles or stinging cells are left stuck on your skin, you can scrape them off using a tool such as a piece of cardboard or a credit card, before treating the area with a cooling balm or antihistamine cream.

If any burning sensations persist, seek medical advice from a doctor or pharmacist.

Mr Auffret said: “We do not all react in the same way to jellyfish stings. We must avoid touching any stranded jellyfish...the stinging cells can live for several hours after the animal has become stranded.”

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