'Killer' shrimps worst alien invader of UK waterways

BBC News 6 Aug 11;

'Killer' shrimp is the worst non-native invader of England and Wales' waterways, says the Environment Agency.

Known as Dikerogammarus villosus, it kills native shrimp and young fish.

The Environment Agency's worst 10 alien invaders include water primrose, giant hogweed and Japanese knotweed which can damage riverbanks and buildings.

The agency said invasive species cost the UK about £1.7bn a year and it will work with partner groups to manage the spread of damaging plants and animals.

Several species of pond plant which have escaped from gardens and parks are also on the list of non-native wildlife which pose the greatest threat to the country's rivers and lakes.

Increased damage to riverbanks and buildings can increase the risk of floods and hit native wildlife.

Tough EU targets

Invasive species can even become so prolific that anglers, fishermen and boaters cannot use the waterways.

Despite growing to just 30mm long, Dikerogammarus villosus has been identified as being the worst alien invader due to its voracious appetite which alters the make-up of habitats it invades.

Other creatures in the Environment Agency's most wanted list include the American signal crayfish which has endangered our native white-clawed species, the topmouth gudgeon fish which hits other species, and the mink, which eats water voles.

Water primrose, the floating pennywort and parrot's feather are pond plants which have caused problems after spreading into the environment, clogging up and damaging water habitats.

Giant hogweed, Japanese knotweed and Himalayan balsam are all taking their toll on riverbanks and other areas across the UK.

The hogweed contains a poisonous sap, the knotweed causes structural damage and all three suppress native plants and cause soil erosion.

The Environment Agency warned that the invasive species could hamper efforts to improve the quality of rivers to meet tough new EU targets.

It said it is already spending £2m a year controlling invasive species, and will be increasing its efforts with partners such as government conservation agency Natural England.

Trevor Renals, invasive species expert at the Environment Agency, said if invasive species are not controlled there is a risk of losing some native species and incurring even more clean-up costs, as well as "falling short of the strict EU targets for our rivers and lakes".

He said: "The Environment Agency will be working with other environment bodies as well as community and volunteer groups to manage the spread of these damaging plants and animals.

"We would urge everyone to help stop the spread of these species by making sure that garden and pond plants don't end up near rivers and parkland and thoroughly cleaning any fishing, boating and canoeing equipment when moving between waterways."

'Most wanted' invaders

1. Killer shrimp
2. Water primrose
3. Floating pennywort
4. American signal crayfish
5. Topmouth gudgeon
6. Giant hogweed
7. Japanese knotweed
8. Himalayan balsam
9. Mink
10. Parrot's feather

* Source: Environment Agency

Environment Agency's 'hit list' of ten most invasive species
A “hit list” of the ten invasive species which pose the biggest threat to native wildlife on Britain’s waterways and cost £1.7bn a year to tackle has been released by the Environment Agency.
Nick Collins The Telegraph 6 Aug 11;

Alien species erode buildings and river banks, raise the risk of flooding and put native wildlife at risk of extinction by colonising their natural habitat and killing competitors.

Some have even clogged up rivers and lakes so much that they can no longer be used by anglers and boaters.

Now members of the public are being urged to take up the fight and stop the spread of foreign plants and animals to new waterways.

Top of the list of threats is the killer shrimp, which despite measuring just 3cm in length has an insatiable appetite and feasts on a vast range of native species such as young fish and other species of shrimp.

This has a knock-on effect on the ecology of the rivers they inhabit, putting insects such as damselflies and waterboatmen under threat, along with any predators further up the food chain.

Other animals on the hit list include the American signal crayfish, which are seriously endangering the smaller and less aggressive white clawed crayfish; topmouth gudgeon, a rapidly reproducing Japanese fish; and mink, which hunt fish, birds and small mammals, especially the water vole.

The most threatening plant listed is water primrose, which covers entire waterways in France and has been found at sixteen sites in England and Wales.

Floating pennywort, giant hogweed, Japanese knotweed, Himalayan balsam and parrot’s feather complete the hit list.

Environment experts fear that rivers rife with invasive flora and fauna could fail to meet rigorous new EU targets on the ecological health of waterways.

Britain’s rivers are in their cleanest state in more than 20 years, with some species such as otters and salmon even returning for the first time since the industrial revolution.

But alien species risk damaging the ecology of waterways by crowding out and killing native species, which can seriously harm the health of the entire ecosystem.

Rivers which do not meet the EU’s targets, which include ecological health measures, by 2015 could attract fines running to millions of pounds.

The Environment Agency spends more than £2 million a year attempting to control invasive species, and a further £9 million of government funding has been dedicated to safeguarding waterways in England.

Trevor Renals, invasive species expert at the Environment Agency said: “River water quality is the best its been since before the industrial revolution. But if we don’t control invasive species, we risk losing some of our precious native species and incurring even more clean up costs.

“We would urge everyone to help stop the spread of these species by making sure that garden and pond plants don’t end up near rivers and parkland and thoroughly cleaning any fishing, boating and canoeing equipment when moving between waterways.”