JELLYFISH:Marine experts behind a jellyfish research project believe the number of the creatures in Irish waters is growing, writes Adam Harvey
IT COULD be the trailer for a horror film: they're out there in vast numbers - uncountable billions of mysterious, heavily armed carnivores, lurking in the murky water off the Irish coast and heading for the same sheltered warmer waters sought by holidaymakers.
But don't panic, say marine experts. While brushing against a jellyfish in the sea is an undoubtedly creepy experience, most of these invertebrates are harmless.
Unless you had the misfortune of bumping into the handful of Portuguese Man O' War known to have floated into northern waters, Irish jellyfish encounters mostly involve squeamish discomfort rather than pain.
That "mostly" qualification is thanks to the swimmer's nemesis, the Lion's Mane.
It can grow to mammoth proportions, with a "bell" of up to 2.3m (7.5ft) in diameter and tentacles that can trail for 30m and inflict painful burn-like stings.
As with all jellyfish, the Lion's Mane's sting is triggered by a mechanical process rather than any conscious effort to attack: contact with a single minuscule hair on a jellyfish's tentacle is like triggering a switch, which shoots out a poisonous needle into the creature's prey. The process helps penetrate the hard shell of floating crustaceans.
"That is quite a vicious jellyfish," confirms Dr Ruth Callaway, project manager at Swansea University with a joint Irish-UK jellyfish research effort called EcoJel.
"They have these stingers that are like nettles to protect themselves," she says, before quickly adding, "but this is to stun prey - they do not hunt humans."
But through sheer weight of numbers, jellyfish do have the power to wreak havoc on the growing fish-farming industry - blooms of them in the Sea of Japan and off Namibia have been clogging the nets of fisherman.
Last year, one 25.9sq km (10sq mile) swarm off the Co Antrim coast was so dense that it smothered Northern Salmon's entire stock of 100,000 fish.
Scientists from Ireland and the UK have embarked on an ambitious project to learn more about the creatures, in the hope of predicting when and where they might swarm.
Marine experts from University College Cork, Swansea University in Britain and Queen's University Belfast are attempting to "tag" jellyfish with microchips.
This will permit the recording of information about the invertebrates' mysterious life: where they float, how deep they travel, whether their journeys through the sea have some mission or whether they're just marine journeymen, going with the flow of currents and tide. Scientists are pulling the creatures out of the water to attach a tag around the central stem of the jellyfish.
It's already known that different jellyfish seem to favour certain areas - aerial observations by the Irish Sea Leatherback Turtle Project last year found moon jellyfish massed along the Leinster and south Wales coasts.
Barrel jellyfish blooms covering several square kilometres have been recorded off Rosslare Harbour in Co Wexford. The project might improve our remarkable lack of knowledge about jellyfish, says Dr Callaway.
Anecdotal evidence suggests jellyfish numbers are growing in tandem with rising water temperatures. This makes sense, she says, because their primary food source - plankton - also thrives in warmer waters. Jellyfish are more common in bays and inlets where the water is warmer. It's news like this that could have Irish swimmers hoping for colder water.
IRISH JELLYFISH
The Moon jellyfish, the Compass jellyfish and the Blue jellyfish will be familiar to anyone who has gazed off the edge of an Irish pier.
Usually less than a foot in diameter, these creatures will usually cause no more than minor irritation to swimmers.
"People seem to respond to them quite differently," says Dr Callaway. "Some people are quite allergic and their stings can be quite burn-like."
The sting of a Barrel Jellyfish, which grows up to 90cm (35in) in diameter, reportedly feels similar to a wasp strike.
The tentacles of the Lion's Mane Jellyfish can inflict serious, burn-like pain, and the tentacles of the creature can reach 36.5m (120ft), longer than the biggest Blue Whale.
"Like the Portuguese Man O' War, when you see them it's almost too late," says Dr Callaway. Several dozen Man O'Wars have washed up on British beaches accompanied by semi-hysteria in the UK press. The creatures' stings are very painful, but rarely fatal.
SPAIN
Spanish fear scourge of the purple stinger:ONE OF the scourges of the Spanish summer is the annual plague of jellyfish, most notably the pelagia noctiluca, better known as the purple stinger.
Hundreds of bathers are treated at first aid posts every year for the unpleasant effects of the non-fatal stings. Some 3,000 people were treated at Red Cross stations this July, but this was almost half the number for 2007.
Although numbers are slightly lower than last year, the problem is still serious. Authorities were forced to raise the yellow warning flags last month on six beaches north and south of Barcelona and further down the coast around Valencia and Alicante.
Marine biologist Veronica Fuentes, of the Barcelona-based Institute of Marine Sciences, is taking part in a project to study the purple stinger in Catalan waters.
"We know there are, and always have been, huge shoals of them out in deeper waters, but we cannot say whether they are on the increase or whether they will come into the shallow waters and beaches. We are trying to find out why some years there are more than in others."
It is believed that this year's late spring rains are partly responsible for the reduction in people being stung. "When the rain flows into the sea it lowers the salinity and temperature of the water, and this creates a natural barrier which keep the jellyfish further out at sea," added Ms Fuentes.
So far there have been no reports of these creatures coming near popular tourist beaches in the Balearics.
The problem in the Mediterranean only concerns the purple stingers, but there have been reports of the more deadly Portuguese Men-of-War around the Biscay coast.
Thirty of them have been captured so far by fishermen. JANE WALKER
ITALY
No need for alarm on the beaches, says expert:THIS SUMMER, as indeed every summer for a while, there have been sporadic reports of jellyfish "invasions" in certain Italian waters.
Yet, Sebastiano Veneri, maritime expert for the Italian environmentalist lobby, LegaAmbiente, says there is no reason for alarmist scaremongering and that the problem certainly should not deter any would-be beach tourist to Italy.
There have been reports in recent weeks that the Ligurian coast, from Genoa down to Portofino, has been especially badly affected by jellyfish. Some bathers, many of them children, have sought medical attention for jellyfish stings.
However, Veneri says there is no particular escalation of the problem this summer and many Italian waters remain jellyfish free. "For the time being, we have no indications of situations that give rise to any particular alarm.
"Recent newspaper reports of growing numbers seem to me a bit wide of the mark." PADDY AGNEW