According to the Department for the Environment, Food and Rural Affairs (DEFRA), non-native invasive species can prey on, compete with and displace native wildlife. The can spread disease and block waterways. They can completely alter the balance of ecology in a water system.
Fish populations can alter, and they can block up waterways which mean boat users have to take different routes. The financial costs can run into millions of pounds.
More top news
A judge rules today on a serial killer from Peterborough's High Court claim that she is entitled to damages for human rights violations.
Cloudy and feeling chilly with rain and drizzle at times.
Rather cloudy with patchy rain. Turning brighter.