Benthic biodiversity in oligotrophic waters: The case study of Is Arenas (western Sardinia, Italy).

We report the distribution of benthic assemblages in Is Arenas Bay, a coastal marine area of western Sardinia characterized by oligotrophic waters and the presence of different habitats, including the seagrass Posidonia oceanica and unvegetated sediments. Gammarids tended to dominate in proximity of the seagrass meadow, while nematods, polychaetes (Lumbrineridae) and bivalves (Tellinidae) increased in well-sorted fine-sand sediments. Among these benthic communities, a wide range of taxonomic groups included as the polychaetes Phyllodocidae, Nuculanidae and Gliceridae, the crustaceans Ostracoda, Caprellidae, Processidae, Isopoda and Portunidae, the mollusks Nuculanidae, Glycymeridae, Naticidae, Eulimidae, and the echinoderms Astropectinidae, Ophiuroidea, Holoturoidea. Overall, the benthic communities of Is Arenas were dominated by taxa sensitive to anthropogenic impact, indicating a high biodiverse and healthy coastal marine ecosystem.