The first occurrence of the brown alga sargassum muticum (yendo) fensholt in the channel islands

An ‘unusual’ alga reported by the Jersey Department of Agriculture was positively identified as Sargassum muticum (Yendo) Fensholt (Phaeophyta, Fucales).Limited field investigations revealed the alga's presence at three sites in Jersey— St Helier, L'Etacq and Le Hocq. The largest population of the two at St Helier occupied a tidal man-made swimming pool and, due to favourable local conditions, was reproductively in advance of English south coast populations. Sargassum was easily the dominant algal species in the pool. Other S. muticum populations in Jersey were at similar stages of reproductive development to English south coast populations. All occupied sites which never completely drained.Sargassum was probably introduced to St Helier by shipping. The other populations may have arisen from fertile drift plants from St Helier or alternatively from one of the large French coast populations. The Channel Islands provide many sites suitable for Sargassum growth and further spread and consolidation of the alga can be expected.