UK's Dirty Dozen invasive species named

The most damaging invasive species clogging up Britain’s waterways have been ‘named and shamed’ by conservationists in an effort to save native wildlife.
Louise Gray The Telegraph 28 Apr 11;

British Waterways identified 12 speciesknown as the ‘Dirty Dozen’ that are suffocating plants and fishes in rivers and ponds across the country.

Most of the plants were introduced to the country from the far East as ornaments for people’s gardens including floating pennywort, water fern, Japanese knotweed, giant hogweed, Australian swamp stonecrop and Himalayan balsam. But they are now pests that suck the oxygen out of ponds, drown out other plants and can even break up concrete.

Introduced creatures include American Signal Crayfish that is driving out the smaller native white claw crayfish. Zebra mussels that travelled on the bottom of ships and zander fish from Russia are harming aquatic life, while Chinese mitten crabs are invading ponds and rivers.

Red-eared Terrapin were introduced from the US via the pet trade while mink was brought over for fur. Both are killing native species.

Chris John, British Waterways national ecologist, asked people to get rid of the species in their own ponds and rivers so they do not spread further or report sightings to the authorities.

“In their native countries these particular species are kept in check by nature, where they are part of an adapted system of predators,” he said. “However, here they have no natural predators and so often quickly outcompete other plants, animals and fish, causing serious problems for wildlife, as well as choking up boats, the towpath and other 200-year old heritage structures such as locks and bridges.

“The destruction of suitable places for wildlife to live is the biggest threat facing Britain’s nature today, these species add to this problem by taking more than their fair share of space, water and sunlight. I am therefore asking people to help us by disposing of these plants and animals safely and carefully selecting alternative plants for their gardens, ponds and aquariums.”

The Dirty Dozen plants and animals are:

Japanese Knotweed

Australian Swamp Stonecrop

Giant Hogweed

Himalayan Balsam

Water Fern

Floating Pennywort

American Signal Crayfish

Zebra Mussel

Zander

Mink

Red-eared Terrapin

Chinese Mitten Crab