Occurrence of the invasive brown seaweed Rugulopteryx okamurae (E.Y.Dawson) I.K.Hwang, W.J.Lee & H.S.Kim (Dictyotales, Phaeophyta) in Morocco (Mediterranean Sea)

Rugulopteryx okamurae , a brown alga native to the temperate western Pacific Ocean, was discovered for the first time in the Mediterranean Sea in 2002, in the Thau Lagoon (France). A new population of  R. okamurae  was discovered in Belyounech Beach with the observation of some specimens fixed near the harbour of Tanger (Strait of Gibraltar-Morocco). As well, the remarkable record of this alga stranded in M’diq beach (Alboran Sea-Morocco). Since its introduction  R. okamurae  has established in the Thau Lagoon (France), self-sustaining populations without displaying an invasive behaviour. Contrary, the newly discovered population in Morocco would classify as invasive. This new record gives the range extension, of this invasive alga, from the southwest of Alboran Sea to the southwestern limit of Gibraltar. The presence of this invasive seaweed in the area may affect negatively the native alga, seagrass and native fauna including fish community.