Non-Native Marine Macroalgae of the Azores: An Updated Inventory

Non-native species (NNS) represent a threat to biodiversity, and their occurrence and distribution should be periodically updated and made easily available to researchers and policymakers. An updated inventory of macroalgal NNS currently present in the Azores was produced based on published reports. Data concerning the first report and the distribution in the archipelago are provided for each species, as well as their respective native ranges and possible vectors of introduction. The resulting list comprises 42 taxa, i.e., 8.05% of the marine flora presently reported in the Azores, with 16 new NNS recorded over the last decade. The most isolated islands of the Western Group presented lower numbers of NNS (4.25% and 6.25%). In contrast, the two islands with the most used marina for transatlantic recreational sailing presented higher numbers (12.90% and 16.87%). Shipping is the main introduction vector (68%), whereas most macroalgal NNS are originally from the Pacific Ocean (31%) and the Indo-Pacific (31%). The presence of 13 species is restricted to single islands, and no species is reported exclusively in the Western group. Asparagopsis armata is the only algal NNS reported from all islands of the Azores. Future work is proposed to support policymaking.