Alien seaweed in Scottish waters

The Japanese seaweed was found growing in Loch Sunart

A Japanese seaweed that could threaten the diversity of native species has been found in Scottish waters.

Heterosiphonia japonica was found by Dr Colin Moore while diving off the Isle of Oronsay, near Loch Sunart, in May.

Since then, the academic from Heriot-Watt University in Edinburgh, has found it in Glenmore Bay, Loch Sunart, Loch Drumbuie and Loch Creran.

Conservationists believe the seaweed's rapid growth could potentially threaten other native species.

Heterosiphonia japonica originates from the Pacific and can form dense tufts up to 30cm in length.

It was first recorded in Europe in 1994, when it was spotted in oyster ponds in the Netherlands.

Since then it has turned up in oyster farms in France and Spain and spread over much of the Norwegian coast.

Dr Fiona Manson, marine advisory officer at Scottish Natural Heritage, said the discovery of the species had given rise to concern.

"At the moment we don't know what impact it will have on marine wildlife, although it is likely it will reduce the diversity of our native seaweeds by outgrowing them, as it has in other parts of Europe," she said.

"Now it is here there is not much we can do to eradicate it but, like wireweed, another non-native species of seaweed spreading rapidly around the west coast, it is important boat users and others take care not to spread it further."