Monsters of the Deep Jellyfish Threaten the World's Seas

Jellyfish infestations along beaches worldwide are troubling tourists and scientists alike. It is a creature that thrives on over-fishing and pollution. But how dangerous is it for the ecosystem?



When oceanographer Josep Maria Gili steps onto the terrace from his office, he sees the crowds of people on the beaches of Barcelona at his feet. To the left lies the Port Olímpic, together with a sculpture that Frank Gehry had built there for the 1992 Summer Olympics: a giant fish made of steel, shimmering in the sunshine and gazing majestically out into the Mediterranean.

Unfortunately, it seems evident today that the renowned architect picked the wrong animal. The fish, with its gills and fins, is no longer suited as a trademark of Barcelona. Nowadays fewer and fewer fish swim beneath the glittering blue surface off the coast of Catalonia; instead, these waters are now more frequently filled with massive quantities of jellyfish.

The marine creatures -- blind and lacking both a heart and a brain, driven by waves and currents -- billow toward the coast, many with poisonous tentacles in tow, not just in Catalonia in northeastern Spain, but virtually everywhere in the world. It has become painfully clear to anyone who has had the bad luck of getting in the way of a poisonous jellyfish that this creature is the new queen of the seas. Such encounters sometimes end fatally -- for the human being, that is.

The 'Jellification of the Seas'

Oceanographer Gili's interest in jellyfish began at about the same time Gehry created his giant fish. It was an exotic discipline, even for a biologist from the Institut de Ciències del Mar. What no one could have known at the time is that today, more than 20 years later, the jellyfish has become the main topic at international conferences. Entire books are written about the supposed "jellification of the seas," and scientists argue over whether jellyfish are displacing fish and other ocean creatures, whether they are assuming control over entire ecosystems and whether we will have to eat them in the future to keep them in check, as the Chinese have done for centuries.

The fact that human beings and jellyfish tangle with one another more frequently than in the past is unpleasant for both sides. It also costs many millions each year, although the exact costs are difficult to estimate. For instance, jellyfish often cause power outages and equipment damage when they enter the cooling water systems of power plants and desalination plants.

Jellyfish are also harmful to fishery. They ruin nets and cause chemical burns on the hands of fishermen. If a jellyfish bloom collides with the nets that separate fish farms from the open water, the creatures' toxins can sometimes kill all of the animals in the enclosures.

And then there is the problem oceanographer Josep Maria Gili can see from his terrace: Jellyfish on the beach, coinciding with the vacation season, are a debacle for tourism. These days it is the reddish, glow-in-the-dark jellyfish Pelagia noctiluca, or mauve stinger, that lurks in the waters off Barcelona. In recent days, Red Cross paramedics have had to treat at least 400 swimmers a day for jellyfish injuries. A yellow warning flag is posted on the beach below, and a voice blaring from loudspeakers warns bathers in Spanish, French and English to be careful around jellyfish.

More and More Jellyfish Blooms

"We are used to jellyfish in the Mediterranean," says Gili, 60, a short, gray-haired man. "But what we have observed here in the last few years is no longer normal." Pelagia noctiluca, for example, doesn't swim from the open sea toward the coast of its own volition. Instead, it is driven by waves and currents, dying where it goes aground. In the Mediterranean, this fate has typically befallen mauve stingers about once every 10 to 15 years. But now the blooms have been happening with much greater frequency, with similar incidents occurring in 2005, 2006, 2007, 2011, 2012 and 2013.

The European Union has also begun to show concern over the frequent jellyfish invasions, which present an additional burden on the already ailing economies of its southern member states. That's why the EU is now funding an international research project that will gather data on the spread of jellyfish in the Mediterranean region for the first time, as well as develop a coastal management strategy. The scientists involved in the project plan to test such strategies as protective nets along beaches and a smartphone app that would enable beachgoers to report jellyfish sightings.

The impetus from Brussels was overdue. Scientists still know little about jellyfish, because the animals are difficult to study. They appear suddenly and unpredictably, as if out of nowhere but in large numbers. But for scientists hoping to collect the creatures and study them in laboratories, jellyfish are difficult to keep alive. Breeding jellyfish in an aquarium is also a complicated undertaking. These obstacles help to explain why there is only a small community of jellyfish experts worldwide.

Gili no longer knows exactly why he decided, years ago, to study jellyfish. Perhaps he found them interesting because he grew up with them, on the island of Mallorca. "When I was young, my father used to rub olive oil on my body before I went swimming, to protect me from jellyfish injuries," he recalls with a smile. "Olive oil is the best protection. A lot of sunscreen also helps."

He and his colleague Verónica Fuentes, 35, are in charge of implementing the EU project in Spain. The most important thing, says Gili, is to educate people. "We tell the tourists that they should come to our country because the Mediterranean is fantastic," he says, "but we also have to let them know that the sea is not a swimming pool. You can enjoy the sun and the warm water here, and sometimes there happen to be jellyfish in the water. You have to be prepared for that."

Discuss this issue with other readers!
6 total posts
Show all comments
Page 1
raymondspchu 07/11/2013
1. optional
Jelly fish, when properly processed, is a delicacy and rather expensive in China. This might be a good business opportunity!
rowston007 07/12/2013
2. Jellyfish threaten the World Seas
Jellyfish do not threaten the environment...they are the environment, and their increased populations are the result of changes in conditions in the seas. Until we clean up our act, the larger populations of jelly fish are acting as "vacuum cleaners" of the mainly phosphate enabled pollution of the seas.
japanreader 07/12/2013
3. We eat Jellyfish in Japan
One thing this article totally misses is that some types of jellyfish are eaten by humans. In fact I had them for dinner last night. My wife prepared Binbanji, a dish thought to have its' origins in Indonesia:chicken, jellyfish and a slightly spicy tofu sauce. As far as I know, jelly fish are eaten in China Japan and Korea. Here in Japan they are known as "kurage". The jellyfish are cut into long spaghetti like strips and eaten like noodles. In fact, the fist time I had kurage I thought it was a type of noodle. Kurage tastes a bit like spaghetti al dente, but is much more flavorful, which leads to it being a favorite summer salad ingredient. The Chinese prepare it in hot sauce and it's a favorite snack when drinking. The giant jellyfish (Japanese blame them on Chinese pollution) aren't an edible type of jellyfish, but they do produce a number of chemicals from them, such as keratin and cellulite, as well as one emulsifier used by some Japanese ice cream makers. who knows? If you have ever visited Japan, you might have eaten jellyfish ice cream and not even known it.
Cole 07/12/2013
4. I guess you didn't get the memo?
This article is completely erroneous! I'm rather disappointed, as I've come to expect more from Spiegel. In reality, the most comprehensive jellyfish study to date - has found no trend in jellyfish blooms over the last 200 years! I hope in the future you'll dig a little deeper! "…there is no robust evidence for a global increase in jellyfish." Paper here:
stefano.piraino 07/13/2013
5. jellyfish on the rise - not much worries
Hi, further information about the MED-JELLYRISK project can be found here on the project website and Recently, the BBC posted an article on it. We fully agree with japanreader: if we can't stop jellies, we can eat them! Stefano Piraino, Med-JELLYRISK Coordinator
Show all comments
Page 1

All Rights Reserved
Reproduction only allowed with permission

Die Homepage wurde aktualisiert. Jetzt aufrufen.
Hinweis nicht mehr anzeigen.