Sea squirt threatens marine life

http://news.bbc.co.uk/go/rss/-/1/hi/wales/north_west/8390635.stm

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Work has begun to clear an invasive creature known as the carpet sea squirt from a harbour before it "smothers native marine life".

The didemnum vexillim is believed to have arrived at Holyhead on Anglesey with visiting leisure craft.

The Countryside Council for Wales (CCW) said that if left unchecked it could spread rapidly and devalue the mussels in the Menai Strait.

Carpet sea squirt comes from Japan and is established in parts of Ireland.

In Holyhead the creature has established itself on the marina's floating pontoons and mooring chains and buoys in the harbour.

Removal will involve fixing massive bags around the underwater structures of the marina.

This stops clean flows of water from reaching the sea squirts, so they suffocate and die.

CARPET SEA SQUIRT (DIDEMNUM VEXILLUM) Spongy textured sea squirt with a leathery feelMustard or pale orangey/yellow or beige colourAppears as pale flat patches or wax dripping from artificial structures below the waterSurface has leaf-like veins with tiny pores<i>Source: CCW</i>

If the eradication techniques are successful the CCW said it could advise other affected areas in the UK on how to get rid of the species.

"It we successfully eradicate the sea squirt, we will work hard to make sure that it does not re-colonise," said Rohan Hold, a marine biologist with CCW.

"This will mean careful monitoring in Holyhead marina and other marinas, and other popular mooring areas throughout Wales to check that it hasn't reappeared," he added.

There are also guidelines for small boat owners on how they can help as simply scraping off the structures the creature colonises will spread the infection far and wide.