First record of drifting Sargassum muticum (Yendo) Fensholt thalli on the Algerian coasts of Cherchell and Sidi Fredj.
The Japanese seaweed Sargassum muticum (Yendo) Fensholt is reported for the first time from the Algerian coasts in Cherchell and Sidi Fredj, which are approximately 80 and 30 km, respectively, west of Algiers. Observations of drifting specimens, collected in March 2015 and March and April 2017, suggest that this non-indigenous species has reached Algerian waters. However, S. muticum cannot yet be considered established since the collected seaweeds were not fixed to substrata, were not fertile, and there was no evidence of colonization. Potential vectors of spread for S. muticum into the area include shipping, oyster farming and ocean circulation. In the future, intensive survey and monitoring actions are needed to detect any fertile or attached fronds.