Jellyfish lurks around Spain’s beaches

23rd July 2008, Comments 0 comments

Swarms of jellyfish will hit Spain’s busy beaches despite the huge amount of spring rains in the past few weeks, says research.

23 July 2008

MADRID - The jellyfish are out there even though they have not arrived yet on Spain's busy beaches in swarms.

A recent expedition organised by environmental organization Greenpeace together with the government-run scientific research council, CSIC, has confirmed that there are huge groups of jellyfish in the open seas of the Mediterranean this summer.

"We have been able to detect immense swarms of Pelagia noctiluca, the mauve stinger, near the Balearic Islands," says Dacha Atienza, a CSIC researcher.

"Especially in the Menorca Strait and in the northern and southern areas of the island the [jellyfish] density reaches 8-15 per square metre."

Atienza says that the expedition took the researchers to the Majorca Strait area, where they noticed an "uninterrupted" number of the creatures.

"What is happening is that the huge amount of spring rains have injected enough fresh water to keep jellyfish away from the coasts longer than in the past," explains Atienza.

Fresh water is one of the key factors in keeping jellyfish from reaching the beaches.

Rainwater, entering the sea through rivers, effectively forms a barrier for the saltwater jellyfish, which drift on currents and tides. Josep María Gil, an expert at CSIC who is also employed by the Catalan Water Agency (ACA), explains.

"It's like a wall that keeps many types of passive sea organisms, like jellyfish, which migrate with the help of sea currents [from getting near to the coast]," says Gil.

"We know little about jellyfish and we need information to take more precise measurements.

Unfortunately, with the changes that have taken place at the Environment Ministry and the winter break, the Jellyfish Plan that we had created has not yet got underway," admits Gil.

Researchers such as Gil state that studies on jellyfish should be done throughout the year on beaches and at sea. "The most important thing is that we can carry out research work throughout the year, following the swarms," he says.

Fish play role too
Another important aspect of the creatures' migrations is their relationship with fish larvae.

"Jellyfish also feed on fish larvae before they hatch," says CSIC researcher Verónica Fuentes. "What we don't know are the numbers or what real impact larvae have on jellyfish."

Fish such as tuna and mackerel also play an important role in containing populations. Scientists blame overfishing in part for the rise in jellyfish numbers. Researchers can prove today that there is a direct connection with jellyfish populations and overfishing.

Turtles, which feed on jellyfish, are also low in numbers.

[El Pais / Sergio Rossi / Expatica]

We invite you to contribute to this article by sending related photos or videos. You can either send them to or add them to our newly-created flickr group at All contributed material will be credited accordingly.

0 Comments To This Article