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.
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There will be a few showers in the north tonight but it will become dry for most, with a risk of frost and fog, especially in the south.
Showers continuing in the north, but clear spells in the south before low cloud develops giving fog over the hills.
An 88-year-old woman has died after a hit and run in Birmingham.