...Professor Graeme Hays, the head of Environmental and Molecular Biosciences at Swansea University, is leading the project. He is an expert on sea turtles, which hunt jellyfish as their principal prey. "There is actually very little known about jellyfish despite the fact that jellyfish blooms may be increasing because of overfishing and climate change, which could have huge socio-economic impacts," he said.
Overfishing in particular allowed jellyfish to get a hold in an ecosystem and take it over, he said. This had been seen off the coast of Namibia and in the Black Sea, where fisheries had collapsed as jellyfish became more numerous than the fish themselves.
"This is a serious threat," Professor Hays said. "In 20 years' time we may be looking at jellyfish and chips, rather than fish and chips." The threat to swimmers was also growing. The stings of some species of jellyfish found in British waters, such as those of the lion's mane jellyfish, were capable of causing death. The project would allow a broad-scale assessment of the role of jellyfish in the Irish Sea ecosystem, he added.
Professor Hays and his Irish counterpart, Professor Tom Doyle, will attach data loggers – small devices which record information such as water temperature and depth – to the biggest species that is found in British waters, the barrel jellyfish, which can measure three feet across.
Once the animals die, it is hoped that the data loggers will be washed ashore and found by members of the public. Tests have shown that the idea is workable in practice.
The scientists hope that they may be able to work out management strategies for fish farms to avoid jellyfish problems, but they will look as well at the possibility of harvesting some jellyfish species as food. This is increasingly happening in Asia. They will also be assembling all the information necessary to treat incidents of stinging from different species.
*Barrel or rootmouth jellyfish
The biggest jellyfish commonly found in British waters, up to a metre in diameter. Robust, with a spherical, solid, rubbery and largely white bell, fringed with purple. The bell lacks tentacles but eight thick, frilled arms hang down from the manubrium (the mouth and arms, underside and centre of bell). Harmless.
Up to 30cm. Similar shape to the lion's mane, but smaller with a blue bell through which radial lines can be seen. Mild sting.
Up to 40cm in diameter. Transparent, umbrella-shaped bell edged with short, hair-like tentacles. Recognised by the four distinct pale purple gonad rings in the bell. Manubrium bears four short, frilled arms. Mild sting.
Typically up to 30cm. Colour variable, but usually has pale umbrella-shaped bell with diagnostic brownish V-shaped markings, 32 marginal lobes and 24 long, thin tentacles. Four thick, frilled arms hang from the manubrium. Mild sting.
Up to 10cm. Has a deep bell with pink or mauve warts, 16 marginal lobes and eight marginal, hair-like tentacles. Manubrium bears four longer frilled arms with tiny pink spots. More serious sting.
*Lion's mane jellyfish
Large, usually 50cm but can reach two metres in diameter. Large, reddish brown, umbrella-shaped bell with mass of long, thin hair-like tentacles as well as four short, thick, frilled and folded arms. Very virulent sting, capable of causing cardiac arrest.
Not a true jellyfish, but a floating hydranth. Up to 10cm long and blue-purple in colour. Upright sail and chitinous float are diagnostic, with a mass of small tentacles surrounding the mouth on the underside. Found in swarms. Harmless to humans.
Not a true jellyfish, but a floating colony of hydrozoans. Oval-shaped, transparent float with crest. Blue-purple, with many hanging fishing polyps below that may be tens of metres long. Extremely dangerous. Rare in the UK but if found in numbers they should be reported.