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Rising Jellyfish Swarms Sting the Mediterranean

Rising Jellyfish Swarms Sting the Mediterranean

A surge in jellyfish numbers in the Mediterranean, and in particular a number of poisonous species, is threatening to choke biodiversity and damage tourism in the area, scientists have warned.

A new report into sharply rising numbers of “gelatinous macrozooplankton”– jellyfish to you and me — in areas of the Mediterranean says that while jellyfish blooms are known to go through population cycles, the high numbers recorded in the past few years is becoming a problem.

“In the last decade, the media are reporting on an increasingly high number of gelatinous plankton blooms… The reason for these reports is that thousands of tourists are stung, fisheries are harmed and even impaired by jellyfish,” say the scientists behind the report, among them Fernando Borea for the General Fisheries Commission for the Mediterranean and the United Nations.

So-called citizen scientists, armed with a bit of know-how and a clever little phone app, have reportedly been tracking the numbers throughout the Mediterranean and have recorded sharply rising numbers over the past four years. So how bad is the problem?

“There are now beaches on the [Italian] island of Lampedusa, which receive 300,000 tourists a year, where people can only swim for a week in the summer,” Salento University professor Stefano Piraino is quoted as saying in the Guardian.

Particular concern has been raised because, among the kinds of jellyfish that are enjoying an upsurge, there are several poisonous varieties including the mauve stinger (Pelagia noctiluca) which has reared its tentacles along the Catalonia and Valencia coast.

The mauve stingers tracked during these surveys have been relatively large and tightly packed, with one estimate putting the density at 30-40 jellyfish per square meter. What’s more, they have been found closer to the shoreline than normal, posing an obvious threat to beach-goers.

Other coastlines affected by the upsurge in wider jellyfish populations include Sardinia, Sicily, Malta and some beaches in Israel and the Lebanon. Several Mediterranean regional authorities are now considering deploying two meter deep nets in order to fend off the jellyfish and create so-called safe swim areas. This, of course, could be hazardous for other marine life.

But what is causing this sharp rise in the numbers of jellyfish?

Scientists say there are several problems, but among them remain two key issues: global warming and over-fishing, both of which have altered the environment in ways that have allowed the jellyfish ideal conditions in which to thrive. For instance, overfishing has removed several of the jellyfish’s key predators. In turn, several species of jellyfish target eggs and larvae of many species of fish and marine animals, creating a cycle that exacerbates the problems surrounding plummeting fish stocks.

Add to this the fact that several of the beaches in the Mediterranean have been altered to make them more desirable for swimmers, for instance by creating breakwaters to protect beaches, and this in turn has allowed young jellyfish an ideal developing ground.

As to how much of an issue this will be in the long-term, and whether the population will continue to rise, scientists don’t yet know. Certainly, moves to protect public health and the viability of tourism in the Mediterranean will have to be thought out.

It is true that this could prove to be only a passing issue, however, scientists are adamant that the problem is indicative of wider environmental issues brought on by a rapidly changing and threatening climate. Sea temperature change is well known to affect marine life behavior and it appears this is just one among many examples.

The news is not all bad, however.

Some have pointed out that a boom in jellyfish numbers may actually be good for the fishing industry if people can be convinced, like the Chinese already have, that jellyfish can provide a tasty meal. Also, because of their almost alien beauty, jellyfish continue to be a draw in many aquariums.

Whether resorts in the Mediterranean and other areas affected by this population increase could effectively capitalize on this — and in ways that will not further harm the environment or the jellyfish — remains a question, but it is worth mentioning that this does not necessarily doom tourism or associated businesses.

It will, however, necessitate a radical rethink of our relationship with jellyfish as they now, and increasingly, cannot be ignored.

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Image credit: Jabber Zhou.

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7:34AM PDT on Jul 13, 2013

thanks for sharing :)

8:16PM PDT on Jun 22, 2013

@ Marg H. "why is this a problem?" Haven't figured it out yet? Why is this a problem? Over proliferation of ANY species [not just humans] is destructive to the entire web of nature. @Jeaneen A. "Just stay out of the water and than the problem is solved" You too? That kind of solution never even worked for ostriches.

10:00AM PDT on Jun 11, 2013

Food source maybe.

3:04AM PDT on Jun 11, 2013

I've always loved jelly fish but this clearly does pose a problem.

12:22AM PDT on Jun 11, 2013


12:18AM PDT on Jun 11, 2013

not enough sea turtles to help keep the population in check

7:37PM PDT on Jun 10, 2013

Not good...

7:21PM PDT on Jun 10, 2013

that is what happens when man introduces animals to a environment that thay do not belong in. or remove to many animals that would be food for or a predator of any given animal. there is a balance in nature and we have placed the heavy hand of MAN on the scales and everything is in danger

5:24PM PDT on Jun 10, 2013


5:03PM PDT on Jun 10, 2013

noted, thanks

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