This dataset contains abundance (i.e., absolute number of speicmens/individuals) of ostracod genera collected during three cruises of the German Research Vessel Polarstern in the Atlantic Sector of the Southern Ocean. The cruises are EASIZ II (PS 48/ANT XV-3), ANDEEP I (PS 61/ANT XIX-3), ANDEEP II (PS 67/ANTXXII-3), and ANDEEP III (PS 67/ANTXXII-4). The samples related to the present file were all collected using an epibenthic sledge, described by (Brandt & Barthel, 1995; Brenke, 2005, see compelte references in Brandão et al., 2021, Zoological Journal of the Linnean Society). These ostracods are both benthic (most specimens collected) and bentho-pelagic (Halocyprididae, which in the case of the present dataset, swam just above the sea floor).

From the Material and Methods session of the paper, which analysed this dataset (Brandão et al., 2021): "The 51 samples studied herein (Fig. 1, Tab. 1) were collected in the Atlantic sector of the SO during four cruises of the projects ANDEEP (I, II and III cruises) and EASIZ (Ecology of the Antarctic Sea Ice Zone) (II cruise) (for details see Brandt et al., 2007b; Arntz & Gutt, 1999). The ANDEEP (Antarctic benthic DEEP-sea biodiversity: colonization history and recent community patterns) project provided samples from the deep continental shelf (753 m) to the abyss (6340 m). While during the EASIZ  project samples were recovered from the relatively shallow continental shelf (189 m) to the deep slope (2076 m). The gear used in the sampling was an EpiBenthic Sledge (EBS), which holds two sampling boxes (opening of 100 cm width and 33 cm height), with one sampler plankton net attached (0.5 mm mesh size for the epinet and supranet, and 0.3 mm for the cod ends) (for a detailed description of the gear, see Brandt & Barthel, 1995; Brenke, 2005). The sledge was hauled over the ground for 10 min at a mean velocity of 1 knot (1852 m/h) . Haul distances were calculated on the basis of the GPS-derived positions of the ship at the start of the haul to the time when the sledge left the ground, and varied from 807 to 6464 m. As soon as the sledge arrived on board, samples were immediately fixed in 96% pre-cooled ethanol and kept for at least 48 h at -20°C.

Contrary to most published studies on ostracods, which are based on subrecent specimens (empty valves), herein the species density data includes only living specimens (=with soft parts). Additionally, because small-sized ostracods could pass through the EBS mesh (300 and 500 μm) during trawling, taxa with a carapace shorter than 500 μm (e.g. Xestoleberididae, some Pontocyprididae, Pseudocythere) were excluded from the statistical analyses. The ostracods were identified to species level (except for the Krithidae) based on appendage and valve morphology. The ostracods from the supra and epibenthic-sledges were pooled as one sample."