Sighting of Saccorhiza polyschides (Lightfoot) Batters (Phaeophyceae, Stramenopiles) in Algeria (Mediterranean Sea): an Insight into Range Expansion Routes

Abstract

In the Mediterranean Sea, the northeast Atlantic seaweed Saccorhiza polyschides (Lightfoot) Batters is uncommon. The only permanent populations are located in the Alboran Sea and in the Straits of Messina (Italy). In contrast, since the early 19 th century, several sightings, on ship's hulls and/or in harbours, reflect the dispersal of propagules which failed to establish in the Mediterranean. Here we report a new sighting of Saccorhiza polyschides, near the port of Jijel, Algeria. This first new record in the Mediterranean for more than a century indicates that the dispersal of propagules continues today. In addition, because of its spectacular size and ease of its observation, it sheds light on the expansion routes of a species at the limit of their current range area.

The Possible Failed Pre-Linnaean Introduction in the Mediterranean Sea: An Archival Case Study of the Brown Mussel Perna perna

“…This strain, which corresponds to the successful invasive strain in the Mediterranean Sea, was unintentionally released from a public aquarium in the Sea of Japan [105] in the spring of 1992 and 1993; it established four colonies, less than 1 m in diameter, which disappeared in the succeeding winters, probably because of low winter water temperatures [105,106]. Another example is that of the large brown alga Saccorhiza polyschides in the Mediterranean, which, despite a number of attempts, never succeeded in colonising the Mediterranean, with the exception of Sicily [107]. The present case of Perna perna, a contemporary worldwide successful NIS, but a failed one in the Mediterranean three centuries ago, constitutes a singular example of a failed introduction because of the scarcity of such cases in the marine realm and, more broadly, because of its reported antiquity.…”