24 November 2009

North American water weed dubbed ‘enemy number one’ by Environment Agency

The UK Environment Agency is fighting a running battle against Floating Pennywort, the most sinister of aliens ever to reach the rivers Cam and Great Ouse.
This North American water-weed was first detected on these rivers in 2006 and with its ability to grow by an almost incredible 20cm in a single day it is now blocking up our local rivers.
Floating Pennywort grows in huge, dense mattresses that can make water look like land and it has kidney shaped, serrated leaves with long stems.
This weed chokes waterways making it difficult for boats to navigate and increases the risk of flooding by slowing down water flow. In large quantities it also poses a threat to fish and other aquatic life by starving the water of light, oxygen and nutrients.
So far this year, Environment Agency Operations Delivery teams based at Ely have spent £50,000 removing floating pennywort from local rivers. They tackle the problem in a number of ways: by using weed cutting boats with special lifting mechanisms as well as weed harvesters and herbicide to try to eradicate this species.
Darren Trumper, Operations Delivery Team Leader for the Environment Agency, said: “We suffer from a number of invasive species along our waterways but floating pennywort is probably the most sinister. Three years ago it was almost non existent in our rivers. This year we have had to clear over 60 km of river to remove this menace.”
Terry Clough, Environmental Monitoring Team Leader for the Environment Agency said: “Floating pennywort is such a problem that it is now a hazard for boaters, a threat to the eco-system of our rivers, including fish stocks. It’s also become a flood risk issue. We successfully bid for some external funding from Defra earlier in the year to help pay for removing floating pennywort.”
Terry added: "We have a number of invasive species along our rivers, such as mitten crab, signal crayfish and Japanese knotweed, but of all these I see floating pennywort as public enemy number one."
Due to the ability of this species to grow so swiftly it is likely that the Environment Agency will have to continue with this programme for some time before floating pennywort can be totally eradicated.