AN ALERT has been sounded over foreign invaders that have conquered Redbridge and made their home in the River Roding.

A top ten of overseas plants and creatures that have made their home in Britain and overstayed their welcome has been issued by the Environment Agency, and nearly all are to be found in the Roding.

Heading the list are the American mink and American crayfish, both of which have prospered at the expense of native creatures.

Environment Agency fisheries and bio-diversity team leader Richard Tyner said: "American crayfish have become really prevalent and our native crayfish hasn't been recorded in the Roding in the last decade.

"The American crayfish do quite well in the Roding, along with most rivers in the south of England, and they are very difficult to control because they are so widespread and so successful at breeding."

The crayfish from across the pond can grow to more than a foot long and are, according to the Environment Agency, "very tasty in a bisque."

Also on the list are plants, including the Japanese knotweed, giant hogweed, floating pennywort, Himalayan balsam, parrots feather, and Australian swamp stonecrop.

The American mink has established a low-key presence on the river and is described as a devastating predator of native wildlife, causing particular problems for water voles and moorhens.

Mr Tyner said: "It's not a species we get a lot of reports about, but they are not a legally protected species so people are able to trap them humanely."

Despite the depredations of the new creatures and recent incidents of pollution, Mr Tyner says that the river is in quite a healthy state, adding: "All the signs are very encouraging. It looks like the fish population is recovering quite well. We've got loads of species at loads of different life stages and we're happy for people to go and enjoy it."