Non-native invasive species are a problem because they can prey on, compete with and displace native wildlife, they can spread disease, block waterways, and alter the balance of ecology in a water system.
Defra - Top 5 species to look out for:
- Killer Shrimp
One of the most invasive species in Europe, it can survive up to 15 days in damp conditions. It kills a range of British species and can spread rapidly. Can grow up to 30mm.
- Floating Pennywort
Called 'water pennywort' or sometimes 'pennywort'. Has shiny, kidney-shaped leaves with crinkled edges and is usually found floating on still or slow-moving water. Can grow up to 20cm a day, blocking out light and reducing oxygen for other plants and animals.
- Zebra Mussel
Zebra mussels are found in rivers, canals and lakes and can block pipe-work and affect lock gates. They can also smother native species and rapidly take nutrients from the water, altering ecosystems.
- Water Primrose
Highly invasive freshwater weed which comes from South America. It has become a serious problem in France where it blocks waterways and overgrows ponds and lakes. It has only recently started to be found in Britain, but if it were to establish widely could cost as much as £242 million to manage.
- Quagga Mussel
Related to the Zebra Mussel but can survive in places it can't and can even displace them. Comes from South-East Europe. Not yet present in Britain. More rounded in shape than the Zebra Mussel and easier to detach from surfaces.
Do you think you might have spotted a dangerous species? If you do, click here and let the Environment Agency know!