First year-round occurrence checklist of mesopelagic "swimmers" collected by an automatic sediment trap on Mooring B (Ross Sea, Antarctica) in years 1995-1996, 2004-2005 and 2014-2016.

Background: Long-term studies of pelagic communities in the Southern Ocean are crucial for understanding biodiversity patterns and detecting the impacts of climate change and other environmental stressors. Here, we provide temporal occurrence and spatial data on Antarctic "swimmers" (i.e. pelagic organisms that are captured by sediment traps deployed on moorings) collected within three projects of the Italian National Antarctic Programme (PNRA) in the Ross Sea sector during the periods 1995-1996, 2004-2005 and 2014-2016. These data were obtained over six Italian Antarctic expeditions carried out between 1994 and 2016. New information: This dataset constitute to the first checklist of Antarctic "swimmers" collected in the Joides Basin, a sector of the Ross Sea (Antarctica), using automatic sediment traps deployed at approximately 500 metres depth on Mooring B (approx. Lat = 74.1514°S, Lon = 175.0906°E). Although primarily designed to study particle and export fluxes, these traps also capture motile pelagic organisms, the "swimmers", that enter actively or accidentally. In total 210,411 individuals were sampled. These represent 68 genera and 68 species, corresponding to 905 occurrence records. These accidental captures provide valuable biodiversity data for zooplankton and micronekton taxa yielding quality information useful to refine species distributional models and occurrence predictions, due to the fact that, together with the biological records, a full set of environmental data (e.g. temperature, salinity and density) continuously collected by mooring sensors.