| Summary: | The Aurora seamount, located on the ultra-slow spreading Gakkel Ridge in the Central Arctic Ocean, has been the focus of recent studies that aimed to explore a new hydrothermal vent field discovered in 2014, Aurora vent field. This site is located at ca., 3900m depth under permanent ice cover (82°53.83'N, 6°15.32'W). It was only in 2019, that the first comprehensive characterization of this area was conducted during the HACON19 expedition. This work describes, the benthic megafaunal communities associated with the Aurora seamount in relation to the proximity to the hydrothermal vent field, using quantitative image analyses. Overall, the substrate composition was heterogene with soft and steep walls where basalts and chimney deposits were covered by a thin layer of hemipelagic sediments. Overall, a total of 28 morphospecies were observed on the Aurora seamount, with Porifera and Crustacea as the most abundant taxa. Megafaunal assemblages varied both in terms of density, composition, and diversity in relation to the distance from the vent field. The changes in environmental conditions, particularly substrate composition (e.g., vents deposits, mud or biogenic cover and basalts), depth and slope, were associated with the changes in community composition of the fauna, with sessile fauna, such as Hexactinellid sponges, being most abundant on hard substrate near the vent field, while in soft sedimented areas, polychaetes and isopods were the most frequent taxa observed. At vent field diversity was overall low compared to the other areas, and the most frequent taxa observed was a single amphipod morphospecies of the Melitidae family, a group also known to be present at the Southern vent field of Loki’s Castle. By contrast, diversity was overall higher further from the vent field, and taxa present showed similarities to other abyssal Arctic studied sites in the region. This work provides new insight into the Arctic seamount and vent- associated communities while highlighting gaps in knowledge that should be addressed in ...
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