A paradise for Maldane sarsi antarctica : preliminary characterization of the marine soft-bottom fauna of False Bay (Livingston Island, South Shetland Islands, Antarctica)

Soft-bottom areas are among the least explored ecosystems in Antarctica. To improve our understanding of these environments, we performed a preliminary assessment of the marine macrobenthic fauna in False Bay, Livingston Island, near Huntress Glacier (South Shetland Islands, Antarctica). Fourteen Van Veen grabs (0.018 m 2 area) were deployed at two stations within the bay at depths of 174–210 m. The samples provided values up to 159 556 individuals m -2 within 15 major taxonomic groups. Annelida Polychaeta was predominant (~93%), followed by Ophiuroidea and Bivalvia at the external station and Bivalvia and Amphipoda at the internal site. Maldanid polychaetes, particularly Maldane sarsi antarctica , constituted 84.62–90.74% of the samples. Total biomass was 6673.25 grams of wet weight per square metre, mainly from Ascidiacea, Polychaeta, Holothuroidea and Ophiuroidea. Approximately 12% of the macrofauna inhabited the sediment (epifauna), while 88% lived into the sediments (infauna). Regarding feeding modes, specimens were detritivores (77.91–82.71%), suspension-feeders (7.59–13.37%) and, infrequently, predators (4.07–5.07%) and grazers (4.63–4.65%). According to the compilation of occurrence records in the Southern Ocean, M. sarsi antarctica has a circum-Antarctic distribution. Furthermore, the population of this species in False Bay appears to be stable and undisturbed with a normal distribution in size structure, with a higher proportion of individuals at intermediate sizes (2.85–4.26 cm). This study provides for the first time detailed descriptions of the macrofauna from the soft bottoms of False Bay, representing a preliminary effort to monitor ecological shifts in this critically important and understudied region, which is experiencing rapid environmental changes within Antarctic marine ecosystems.