A previously unrecorded invasive seaweed has been discovered in the Fal and Helford Special Area of Conservation. Wakame is large, brown non-native kelp associated with the temperate waters of Japan, China and Korea.

It is hoped that the early detection of this invasive species, and the quick response for its removal taken by a team from Cornwall Wildlife Trust’s Investigate Invasives project, Natural England and the Port of Truro, will prevent further spread.

Wakame, scientific name Undaria pinnatifida, grows rapidly and is regarded as invasive with the potential to outcompete native seaweed communities. In recent times it has been introduced to European shores for commercial interest, however, up until now has only been recorded in the UK as far west as Plymouth. It can form dense mats that clog up marinas and recreational areas as a result of its prolific growth.

Kevan Cook Lead Advisor for Natural England’s Cornwall, Devon and the Isles of Scilly Marine team advises, “Follow up surveys will need to be undertaken to check for further outbreaks in case spores released by the kelp have settled further afield. The Fal Estuary is part of a site of European importance, and Natural England is keen to be part of any work that will maintain the special biodiversity of the estuary.”

Lisa Rennocks, Investigate Invasives Project Officer from Cornwall Wildlife Trust says: “One of the ways in which non native organisms can be introduced is on the hull of both commercial and recreational boats. We are trying to build up a picture of which non-native invasive species are threatening our coastal waters, and would like boat owners and marinas to watch out for anything unusual when they are cleaning off the hulls of their boats as there may be invasive species amongst the fouling communities.”