COMMENTARY: And Then I Was Surrounded

Swimming with Jellyfish off the Spanish Coast

The author gets a hands-on look at the jellyfish explosion off the north coast of Mallorca.© Pascal Saez

The north coast of Mallorca is one of the few still relatively unspoilt stretches of Mediterranean coastline left in Spain. It felt like the ideal escape from the overbuilt costas of the mainland for a week in late June, and a chance to spend afternoons swimming with careless abandon in secluded coves. It didn"t quite work out that way.

On the first day there were jellyfish at the tiny beach in Cala San Vicente. Not many, but enough of them that one had to progress gingerly and scan the water ahead. Not a huge deal, but troubling.

A couple of days later however, at a larger cove near the town of Soller, little groups of Mauve Stingers (Pelagia Noctiluca) could already be seen bobbing in the shallows along the beach. There were a few people bathing and occasionally someone would shriek in mock terror aftera narrow miss amid their friends" laughter.

It made more sense to wear scuba-diving goggles this time, in order to spot and evade the enemy. But even so, it was impossible to relax one"s attention for more than 30 seconds, as there was always one or more new jellyfish suddenly hovering a couple of meters away.

Then something else caught my eye. On closer inspection, the strange little contact lens-shaped objects in suspension all around were indeed newborn, pulsating jellies. There must have been several hundred specimen per cubic meter of water, that is to say probably hundreds of thousands, if not millions of the blighters in the bay. Thankfully, they don"t sting at that age. Once aware of their presence, it felt like diving through clouds of translucent lentils, under the malevolent surveillance of their adult guardians.

These creatures do not attack swimmers and stings only occur due to accidental contact. Their capacity for autonomous movement is very limited. They rely largely on currents to drift.

Out by the shore, a tourist from New Zealand had made it a mission to skewer every stinger he could get his hands on with wooden sticks and throw them onto a pile on the beach.On other outings further along the coast, the jellyfish count was low enough that swimming could be enjoyed freely, and the week went by without painful incidents.

But all along Spain’s Mediterranean littoral, every summer for the past few years, tens of thousands of holidaymakers have been suffering stings and many have had to seek medical treatment for "burns" that leave temporary streaks akin to whip marks on the skin.

The highly venomous Portuguese Man o" War has an air-filled top membrane that acts as a sail.© NOAA

Large-scale jellyfish population growth followed by rapid decline used to occur periodically in cycles of several years. It is now much more frequent and large blooms of jellyfish have almost become a permanent fixture in the Mediterranean. Recently, a swarm of more than 500 of the dreaded Portuguese Man o" War was even reported off the coast of Andalucia. Thanks to their air-filled top membrane that acts as a sail, they can also use winds to drift across the oceans. These highly venomous creatures are not usual residents of the Mediterranean, and were blown in from the Atlantic through the strait of Gibraltar.

The jellyfish"s enterprise of colonization has been going almost unchecked, as their natural predators such as swordfish or tunas are being dangerously overfished, partly because of the high rates of illegal or underreported catches. Since stocks of smaller fish are also dwindling, the stinging invertebrates have free access to an ever-greater share of the plankton and small marine organisms that they otherwise had to compete for with other inhabitants of the sea. They also feed on fish eggs and larvae, further undermining their rivals. Similar phenomena have been reported in other parts of the world.Perhaps this same mechanism that causes the exponential expansion of a species thanks to the lack of predators and an abundance of food could work in reverse and help regenerate big fish populations? But for that, a moratorium, or drastic reductions on fishing would need to be implemented. Even so, scientists point out that once one species has achieved predominance in an ecosystem, it is quite difficult to restore the lost equilibrium.

Sadly, a halt to fishing activities seems unlikely at present. Last year in November 2008 an international conference organized by ICCAT (International Commission for the Conservation of Atlantic Tunas) took place in Morocco to agree on a reduction of Mediterranean bluefin tuna catch quotas. It was another disappointment to environmentalists. A moratorium, demanded by many environmental groups, was rejected. The new quotas, which will reduce permitted volume of catches by a total of 30% by 2010, still exceed even ICCAT"s own scientists" recommendations. A small extension of two weeks on the fishing ban during the spawning period was also granted.

Other factors that play in favor of the jellyfish and contribute to the explosion of their population are the run-off of residues from agricultural fertilizers into the sea. These effluents provide nutrients for the organisms on which jellyfish feed and can cause a drop in oxygen levels in marine environments that are harmful to fish, but in which jellyfish can still thrive.

The natural habitat of jellyfish is in the high seas, 20 to 30 nautical miles off the coast. So why are they now making a habit of visiting the shore? According to scientists like Josep-Maria Gili, research professor at the Institute of Marine Sciences in Barcelona, this is due to climatic and meteorological conditions. As overall levels of precipitations in southern Europe have fallen in recent years, the reduced influx of fresh water into the sea through rivers has caused the salinity of coastal waters to rise.This less-saline coastal fringe acted as a barrier, but now oceanic waters can periodically reach continental areas, bringing the swarms with them. A rise in sea water temperatures due to global warming is also said to add to the problem by changing current patterns, as well as favoring jellyfish population growth.

After several years of observing the phenomenon, the Spanish authorities have started to take concrete measures to try and defend the beaches against the gelatinous invaders, fearing their impact on a tourism industry already weakened by the global crisis and the low value of the British pound against the euro. Lifeguards have been issued with jellyfish alert flags to warn bathers. The Plan Medusas ("Plan Jellyfish"), launched by the Ministry for the Environment in 2007 has been extended to the entire coast for this summer. Marine biologists and volunteers are monitoring swarm movements and trying to remove them from the water with specially equipped boats if they get to within 200 meters of a busy beach. But the phenomenon of recent jellyfish proliferation has so far not been studied in sufficient depth to allow researchers to predict future trends.

For Josep-Maria Gili, these events are a clear indicator of the poor state of health of the oceans, and the only solution lies in a change in the way in which marine resources are managed.