The invasive brown seaweed Rugulopteryx okamurae (Dictyotales, Ochrophyta) continues to expand: first record in Italy
Giancarlo Bellissimo, Marı́a Altamirano, Antonio‐Román Muñoz, Julio De la Rosa, Tin Hang Hung, Gabriele Rizzuto, Salvatrice Vizzini, Agostino Tomasello
Abstract
The brown seaweed Rugulopteryx okamurae (Dictyotales, Ochrophyta), native to \nthe Pacific Ocean and widely distributed in Asia, has been recently recognized as \nan emblematic case of biological invasion by marine macroalgae in European waters. \nSince 2015 and from the Strait of Gibraltar, R. okamurae has rapidly spread towards \nAtlantic and Mediterranean coastal areas exhibiting an invasive behaviour with \nsignificant ecological and socio-economic impacts. Here, we report the first \nmorphologically and genetically confirmed observation of this species in Italy, \nalong the north-western coast of Sicily (Gulf of Palermo). Specimens were found as \ndrifted material and as an established population on Posidonia oceanica, representing \nits new eastern distribution limit in the Mediterranean Sea, as the species was \npreviously established in Marseilles (France). Furthermore, we performed a favorability \ndistribution model with the current introduced distribution of the species for the \nMediterranean, which shows most of the western Mediterranean, including the \nBalearic archipelago, Corsica and Sardinia, central Mediterranean, including Sicily, \nand the northern coast of Africa together with eastern Mediterranean basin, as \nhighly favorable for R. okamurae. The most probable vectors for this introduction \nare sea currents and maritime traffic, including fishing activities. This hypothesis was \nsupported by some of the ranked variables in the favorability model, i.e., current \nvelocity, and the proximity of the introduced population to fishing ports. These \nresults are a warning that the species can cover large sea distances via sea currents, \nthus also threatening the ecosystems and marine resources of the central and eastern \nMediterranean Sea, as these areas are forecasted to be highly favorable regions for \nthe species. We suggest coordinated actions at the European level with stakeholders \nin the fishing sector regarding prevention, both because it is a highly affected sector \nand because it potentially has a very important role in the dispersion of the species.