This week it’s #InvasivesWeek – and DEFRA are spreading the word about species that can cause big problems. We’re getting involved because the rivers and wetlands of East Anglia are home to a range of fascinating wildlife, but some foreign invaders are causing problems for our water network and our native species. These are the top five invasive species causing problems in our region and what we can do to tackle them:

Zebra mussels1. Zebra and quagga and mussels
Zebra mussels, originally from Russia, are now widespread in waterways across our region while the similar quagga mussel is present in the Lee Valley and west London. These tricky customers can multiply fast and clog up the intake pipes that come from our reservoirs. They also help to encourage the growth of blue-green algae, harmful to humans and many wildlife species. Here at Anglian Water we’ve had to spend many thousands of pounds a year dealing with zebra mussels, including half a million pounds on a special tank at our Rutland Water site to filter them out of the system.

Killer shrimp2. Killer shrimp
The natural home of the killer shrimp – or Dikerogammarus villosus to those in the know – is the tributaries of the Black Sea and Caspian Seas. But now they can be found in large numbers at Anglian Water’s Grafham Water reservoir. As the name suggests they are an aggressive species, killing native wildlife including some fish. They are voracious breeders and experts believe they will prove impossible to eradicate – however, we can help to slow their spread. We have biosecurity measures at Grafham Water to tackle killer shrimp. Anglers and boaters are urged to follow the Check, Clean, Dry steps: Check your equipment and clothing for organisms, Clean and wash all equipment, footwear and clothes thoroughly and Dry all equipment and clothing.

Himalayan Balsam3. Himalayan Balsam
As the name suggests, Himalayan Balsam – also known as Policeman’s Helmet because of the shape of its flowers – was first discovered in the mountains of south Asia. It was introduced as a cultivated plant in gardens in England in the 19th Century but later began to take over riverbanks, easily outcompeting native plants. When it dies back in winter it leaves river banks vulnerable to erosion. This causes sedimentation which is expensive for us to clean up. One way to help the fight against Himalayan balsam is to download the Plant Tracker app developed by the Environment Agency and Bristol University onto your smart phone to help you submit records of it. At Anglian Water we’re helping through our funding of and participation in the RiverCare project, which helps local volunteers to keep their local stretch of river tidy and free of invasive plants.

Signal crayfish4. Signal crayfish
An American immigrant, the signal crayfish has run rampant through the nation’s waterways in recent years. It outcompetes our native white clawed crayfish and spreads crayfish plague which kills them. They can grow to large numbers feeding on everything else in the river, thereby reducing river’s wildlife value and they can burrow in banks, destabilizing them and causing a flood risk. They can grow up to 18cm and according to some people – including celebrity chef Gordon Ramsey – they are a delicious alternative to lobster for our dinner tables. Again, anyone using our waterways is urged to follow the points of the Check, Clean, Dry campaign to stop them spreading further.

Japanese knotweed5. Japanese knotweed
This fast-spreading plant was first recorded in the UK in Glamorgan in 1886 and is now a major headache for gardeners and property developers. It is often found on river banks and has such an economic impact that the Government has vowed to tackle it – even proposing fines and court orders for anyone failing to control it. It can grow through concrete and gaps in floors and patios, causing expensive damage. It needs to be removed carefully and legally, so if you find it on your property, take specialist advice before doing anything.

Posted by Anglian Water