Daniel Álvarez-Canali

The primary vectors for the introduction of alien algae are aquaculture and vessel biofouling. By providing diverse artificial substrates, marinas and ports act as key reservoirs for the establishment of these species and serve as essential sites for studying their expansion. Therefore, macroalgal communities in ten recreational marinas of Tenerife (Canary Islands) were studied across different artificial substrates (light-exposed and shaded pontoons, buoys and ropes) and port zones (inner and outer). Multivariate and univariate analyses revealed that species cover, and morpho-functional traits were significantly influenced by marina size, zone, and their interaction, while the statistical approach identified substrate type as a primary ecological filter. The most abundant species were recorded, together with key functional traits and introduced taxa. Buoys and light-exposed pontoons hosted the greatest species richness, highest diversity indices, and most introduced species, which were dominated by simple, opportunistic forms (annual, ephemeral, and turf growth forms). Conversely, shaded pontoons and ropes supported lower biodiversity, with communities limited to stress-tolerant taxa. Large marinas had more homogeneous algal communities, fewer variable traits, and a greater presence of alien species. This study shows that port structures change algal communities and indicates that buoys and light-exposed pontoons are key places to monitor and manage these invasions. The filamentous annual species Antithamnion villosum is recorded for the first time for the archipelago in these habitats.

Sargassum species play a key role in habitat formation in tropical and subtropical regions; however, species identification has been hampered by the phenological plasticity exhibited in response to environmental conditions and life history. Molecular phylogenetics has challenged taxa circumscriptions and proven critical in delimiting species in this genus. Yet, the Atlantic species of Sargassum remain poorly understood, and recent studies have shown low molecular diversity between the species in the NW Atlantic. Here, we expand the taxon sampling to the NE Atlantic to assess the diversity of Sargassum in the Atlantic basin, based on a comprehensive morphological and multigene approach. We selected genes commonly used in delineating species in this genus (ITS2, rbcLS, cox3, mtsp) and explored additional markers (cox2, nad6, psbC, clpC, atpB) to infer the phylogenetic relationships between the morphospecies observed in the NE Atlantic. Phylogenetic analyses using single‐gene and multigene alignments including 185 new sequences confirmed the low molecular diversity and supported the distinction of a single clade in Sargassum section Sargassum of N Atlantic benthic species. In contrast, morphological analysis resulted in the identification of 10 species and three new morphospecies that we described here but opt not to equate to species until further molecular evidence is available. Our results were congruent with previous findings from the NW Atlantic and highlight the morphological and ecological diversity of Sargassum in the Atlantic. These results suggest a recent colonization and incipient speciation of Sargassum in the Atlantic basin and showcase the need of further high‐throughput analyses.