Molecular Biology and Genetics
Barcode data: Sargassum muticum
Statistics of barcoding coverage: Sargassum muticum
Public Records: 3
Specimens with Barcodes: 11
Species With Barcodes: 1
Sargassum muticum, commonly known as the Japanese wireweed, is a large brown seaweed of the genus Sargassum. It grows attached to rocks by a perennial holdfast up to 5 cm in diameter. From this holdfast the main axis grows to a maximum of 5 cm high. The leaf-like laminae and primary lateral branches grow from this stipe. In warm waters it can grow to 12 m long, however in British waters it gives rise to a single main axis with secondary and tertiary branches which are shed annually. Numerous small 2-6 mm stalked air vesicles provide buoyancy. The reproductive receptacles are also stalked and develop in the axils of leafy laminae. It is self-fertile.
Originally from Japan, by 1995 it had been found in Strangford Lough, County Down, Northern Ireland, this is an extension of the distribution of this invasive species. Herbarium specimens are now stored in the Ulster Museum (BEL catalogue numbers: F11241 - F11242; F11182 - F11185). By June 2009 it has become widespread in Ireland. The species was first found in the British Isles in the Isle of Wight in 1973. It is thought to have gained worldwide distribution through being transported with Japanese oysters (Crassostrea gigas). There is much concern about its impact on the coastal environment. It has become a nuisance forming large detached mats, clogging marinas, recreational areas and other sports facilities. It can foul fishing lines, clog pipes of boats and trap debris.
The species is particularly tenacious with fast growth rates, high reproductive rates and an ability to spread vegetatively.
Sargassum muticum has a range stretching from Campbell river, British Columbia to Baja in California. In Europe it now extends along the coasts of Great Britain, France, Scandinavia, Baltic Sea, Helgoland, Netherlands, Ireland, the Iberian Peninsula and into the Mediterranean from Italy and the Adriatic. It is recorded from Japan, China and Alaska.