An impressive invasion of jellyfish on the beaches of the Atlantic coast

The phenomenon is common in May and June, but this year, the quantity of jellyfish present is exceptional, according to locals and coastal specialists.

At the start of the week, Châtelaillon-Plage, La Rochelle, Royan, Pornic, Pornichet, Quiberon and Lorient are the municipalities on the Atlantic coast most affected by this invasion.

Internet users, amused or annoyed, have published numerous videos of the carpets of jellyfish that have been covering the beaches for a few days.

Why this massive arrival of jellyfish?

The massive arrival of jellyfish on the coast and its beaches can be explained by these three factors:

• a rapid rise in water temperatures: on the Atlantic coast, the water has warmed up by an average of 3 to 4°C in the space of three weeks. The temperature now reaches 16°C north of the Atlantic coast, and 18 to 19°C in the southwest. Rising temperatures are the main cause of jellyfish proliferation.
• marine currents: jellyfish are carried by surface currents, especially when they are warm.
• environmental factors: overfishing suppresses the number of potential predators of jellyfish. Where fish disappear, jellyfish proliferate, just as maritime pollution, especially of agricultural origin, is favorable to them.

Predicting the arrival of jellyfish on the beaches remains impossible to date, as the number of parameters that come into play is great.