Beware the duckbot

The duckweed that smothers ponds faces a new and deadly enemy: a ravenous
solar-powered duck. Invented by Alex Smith of Solar Solutions Fountains in
Kington, Herefordshire, the duckbot comprises a floating waterwheel which scoops
up the surface vegetation as it ambles about the pond. The wheel is turned by a
trickle of water falling onto the paddles from a solar-powered pump. The weed
gathered by the paddles is dumped in a chute. Smith plans to scale up the design
a hundredfold to clean up canals and larger watercourses.