Aliens have invaded the waters around Britain, causing havoc in the seas and bringing with them tropical diseases. Chinese mitten crabs are officially listed as one of the world's 100 worst invasive species.
They can cause damage to fishing gear and river banks, block intake screens, modify natural habitats and compete with native species, and it is this economic and ecological damage that makes this crab such an unwelcome arrival.
Across the Atlantic, thousands of people have died in cholera outbreaks carried across oceans in the ballast tanks of ships.
The damaging traffic goes both ways, with creatures and plants from Britain now turning up in the waters off South America.
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A review by PML Applications Ltd, the wholly-owned subsidiary of Plymouth Marine Laboratory (PML) and Plymouth University found there were 44 non-native species which had become invasive with high ecological impacts in the northeast Atlantic and 15 in the less well studied southwestern Atlantic.
Most had been carried in ballast water of ships, or attached to their hulls.
But aquaculture – such as growing Pacific oysters in rivers like the Helford estuary – has also been a very significant way in for aliens.
Accidental introductions of non-native species has been of increasing concern since the 1980s.
Cecilia de Castro, lead author of the review, said the study highlighted the importance of the International Maritime Organisation's Ballast Water Convention – which the UK has yet to sign up to.
image: http://www.plymouthherald.co.uk/images/localworld/ugc-images/276351/binaries/34108613.jpg
Cecilia Tinidade de Castro examines specimens at Plymouth University
Professor Jason Hall-Spencer is coordinating the UK-Brazil collaboration.
He said: "An estimated 10,000 marine species are transported around the world in ballast water every day. This sometimes causes outbreaks of diseases such as cholera in which thousands of people die, and commonly introduces toxic algae which can cause massive kills of aquatic life.
"I would hope the UK signs up to the United Nations ballast water regulations to help secure healthy productive seas."
A consortium of research institutes is asking for members of the public to report mitten crab sightings.
Read more at http://www.cornwalllive.com/plymouth-marine-laboratory-at-plymouth-university-say-there-are-44-aliens-species-in-our-waters/story-30093878-detail/story.html#yf3kBvZe4YURqI5p.99
