Jellyfish swarms

Ferry study of jellyfish 'threat

Very little is known about the mauve stinger

Scientists have posted jellyfish spotters on Irish Sea ferries to study a breed with a painful sting which could swarm along the Welsh coastline.

Swansea University marine biologist Dr Jon Houghton has been given £50,000 to find out how many mauve stingers there are between Wales and Ireland.

The small purple jellyfish recently wiped out £1m worth of salmon at fish farms in Northern Ireland.

Known as pelagia noctiluca, they have a wasp-like sting and glow in the dark.

Swarms of the jellyfish, which vary in size from a 10p piece to the size of a clenched fist, have affected Mediterranean beaches.

They are small enough to drift through the mesh of salmon cages and in November 2007 billions in a layer 35ft (10.7m) deep and covering 10 square miles of water wiped out 120,000 salmon in a fish farm in Glenarm Bay, Antrim.

This was the first major infestation of the mauve stingers affecting British waters and scientists suspect that global warming is probably the principle cause....