Increasing numbers of jellyfish are recorded each year, which experts explain is a result of a variety of problems caused by humans. They cite the main reason as over-fishing, which reduces the number of jellyfish predators in the sea, followed by pollution and climate change. With rising temperatures and heatwaves across the Mediterranean, there are more jellyfish found on beaches. If jellyfish are spotted on the beach, the advice is to avoid swimming in the sea for at least a day or two.
More information here.