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- Non-indigenous seaweeds in the Northeast Atlantic Ocean, the Mediterranean Sea and Macaronesia: a critical synthesis of diversity, spatial and temporal patternsPublication . van der Loos, Luna M.; Bafort, Quinten; Bosch, Samuel; Ballesteros, Enric; Bárbara, Ignacio; Berecibar, Estibaliz; Blanfuné, Aurélie; Bogaert, Kenny; Bouckenooghe, Silke; Boudouresque, Charles-François; Brodie, Juliet; Cecere, Ester; Díaz-Tapia, Pilar; Engelen, Aschwin; Gunnarson, Karl; Shabaka, Soha Hamdy; Hoffman, Razy; Husa, Vivian; Israel, Álvaro; Karremans, Mart; Knoop, Jessica; Le Gall, Line; Maggs, Christine A.; Mineur, Frédéric; Parente, Manuela; Perk, Frank; Petrocelli, Antonella; Rodríguez-Prieto, Conxi; Ruitton, Sandrine; Sansón, Marta; A Serrao, Ester; Sfriso, Adriano; Sjøtun, Kjersti; Stiger-Pouvreau, Valérie; Surget, Gwladys; Taşkin, Ergün; Thibaut, Thierry; Tsiamis, Konstantinos; Van De Weghe, Lotte; Verlaque, Marc; Viard, Frédérique; Vranken, Sofie; Leliaert, Frederik; De Clerck, OlivierEffective monitoring of non-indigenous seaweeds and combatting their effects relies on a solid confirmation of the non-indigenous status of the respective species. We critically analysed the status of presumed non-indigenous seaweed species reported from the Mediterranean Sea, the Northeast Atlantic Ocean and Macaronesia, resulting in a list of 140 species whose non-indigenous nature is undisputed. For an additional 87 species it is unclear if they are native or non-indigenous (cryptogenic species) or their identity requires confirmation (data deficient species). We discuss the factors underlying both taxonomic and biogeographic uncertainties and outline recommendations to reduce uncertainty about the non-indigenous status of seaweeds. Our dataset consisted of over 19,000 distribution records, half of which can be attributed to only five species (Sargassum muticum, Bonnemaisonia hamifera, Asparagopsis armata, Caulerpa cylindracea and Colpomenia peregrina), while 56 species (40%) are recorded no more than once or twice. In addition, our analyses revealed considerable variation in the diversity of non-indigenous species between the geographic regions. The Eastern Mediterranean Sea is home to the largest fraction of non-indigenous seaweed species, the majority of which have a Red Sea or Indo-Pacific origin and have entered the Mediterranean Sea mostly via the Suez Canal. Non-indigenous seaweeds with native ranges situated in the Northwest Pacific make up a large fraction of the total in the Western Mediterranean Sea, Lusitania and Northern Europe, followed by non-indigenous species with a presumed Australasian origin. Uncertainty remains, however, regarding the native range of a substantial fraction of non-indigenous seaweeds in the study area. In so far as analyses of first detections can serve as a proxy for the introduction rate of non-indigenous seaweeds, these do not reveal a decrease in the introduction rate, indicating that the current measures and policies are insufficient to battle the introduction and spread of non-indigenous species in the study area.
- Diversity and origin of the genus Lobophora in the Mediterranean Sea including the description of two new speciesPublication . Vieira, Christophe; Aharonov, Andre; Paz, Guy; Engelen, Aschwin; Tsiamis, Konstantinos; Einav, Rachel; De Clerck, OlivierThe brown algal genus Lobophora is widely reported from the Mediterranean Sea. Contrary to studies in the Indo-Pacific and Caribbean regions, little attention has been given to Lobophora in the Mediterranean Sea, at least using molecular tools. To address this knowledge gap, we sampled specimens across the Mediterranean Sea (Spanish coast, Balearic Islands, Greece and Israel), with an exhaustive effort in the Balearic Islands. Molecular analyses disclosed the presence of three species, none of them conspecific with the name L. variegata, as they were recorded up to now in the Mediterranean Sea. The most common species in the Mediterranean Sea is L. delicata. We here describe L. schneideri sp. nov., so far found only in Haifa Bay (Israel), where it forms large and dense populations. Similar to L. delicata, L. schneideri occurs across the North Atlantic Ocean. Though a recent range expansion or introduction cannot be ruled out, we regard the North Atlantic Ocean, including the Greater Caribbean and the Mediterranean Sea, as the natural range of both L. schneideri and L. delicata. A third species, described here as L. lessepsiana sp. nov., is found along the Israeli coast as well as in the Red Sea and is most probably a recent introduction through the Suez Canal. Further exploration along the North African coast, the Levantine Sea and the Aegean Sea, would probably increase the currently known species diversity for this group in the Mediterranean Sea.