AN unwanted visitor has been found lurking in the bottom of Worcestershire’s rivers and canals.

The shrimp is a cousin of the killer shrimp and its discovery is sending a shiver down environmentalists’ spines, after it was found right here in the heart of the England.

There are fears it could eat its way through the small native invertebrate species inhabiting the bottom of the watery food chain, completely changing our waterways’ eco-systems.

The shrimp – Dikerogammarus haemobaphes – is a relative of several varieties of killer shrimp which have been steadily eating their way through the native river species, since it was unwittingly introduced from Central Asia.

Until now, the shrimp – which can grow to the size of a fingernail, has been scuppered by Britain’s traditional defence the English Channel, although there have been three isolated outbreaks in the UK previously.

It is believed people moving from Europe to England are the most likely culprit for its appearance here – with one possibility it was brought here inadvertantly in the ballast water carried by merchant shipping.

The freshwater shrimp were only discovered by chance during a routine test on the Severn at Bevere village on the outskirts of Worcester.

They were then discovered in separate tests on the Worcester to Birmingham Canal at Kidderminster.

David Throup, regional manager of the Environment Agency, said it was difficult to predict what the shrimp’s effect on native species could be.

“It has taken millenia for the our waterways’ eco-systems to form, so to introduce a new species which is highly adaptable means we cannot predict what will happen,” he said. “Because it likes mud, it’s likely to spread far and wide, making it worse than its ‘killer shrimp’ cousin.

“There’s no way to stop it, now it’s here – we can only try and slow its spread.”

John Cheyne, Worcester resident and the Angling Trust’s regions co-ordinator, said: “The big difference is that this is the first time its been found in the river – in still water it can be contained.

“They are very aggressive, they out-compete native species – it’s a bit like the grey squirrel and the decline of the native red squirrel.

“It could have a devastating impact here.”

Experts are hoping the shrimps’ spread can be slowed by following the Check, Clean, Dry discipline calling on water users, such as anglers, kayakers and boaters, to check, clean and dry all their equipment after use, before using it on another watercourse, with further tips at nonnativespecies.org/checkcleandry

Anyone with photos of the invading shrimp is asked to e-mail them to alert_nonnative@ceh.ac.uk for identification.