Acoustic backscatter data were collected on board the RRS James Clark Ross during cruise JR17002 on 20/01/2018 in Bransfield Strait and the caldera of Deception Island. Data were collected using a Simrad EK60 echosounder at 38, 70, 120 and 200 kHz. The EK60 was calibrated on 07/01/2018 in Stromness Harbour, South Georgia. More information about the calibration can be found in the Cruise Report for JR17002. This work was carried in the frame of the Polar Ocean Ecosystem TimeSeries - Western Core Box (POETS-WCB) project.

Concentrations of dissolved and atmospheric nitrous oxide, N2O, were measured in the austral spring of 1992 in the Drake Passage and Bellingshausen Sea as part of the United Kingdom Joint Global Ocean Flux Study expedition to the Southern Ocean. The measured atmospheric mixing ratio was 313 +/- 5 parts per billion by volume, in agreement with the hemispherically corrected global mean. In the Drake Passage, surface N2O saturations were generally very close to atmospheric equilibrium, 99.7 +/- 3%, although several anomalous points were associated with the presence of frontal and eddy-like features within the Antarctic Polar Frontal Zone and at the Continental Water Boundary. Further to the south, a series of oceanographic stations and two surface transects along the 85 degrees W meridian between 65.28 degrees S and 70.32 degrees S revealed a transition from undersaturated conditions in open water to oversaturated conditions in the marginal ice zone, in the upper mixed layer (75-100 m). These observations reflect upwelling of Circumpolar Deep Water at approximately 70 degrees S, resulting in the accumulation of N2O under the winter sea ice and its subsequent release to the atmosphere following the ice retreat. Sea-air N2O fluxes were estimated from the product of the surface N2O anomaly and the modelled gas transfer coefficients of Liss and Merlivat [1986] and Wanninkhof [1992] to find a maximum rate of +3.1 micromole N2O m-2 d -1. North of the upwelling region, Antarctic Surface Water formed from the mixing of surface waters and ice melt was moderately depleted in N2O with respect to the atmosphere, a minimum 90% of saturation. This sink area was estimated to extend between 65.28 degrees S and 69.57 degrees S with a mean sea-air flux of between -0.6 +/- 0.4 and -0.9 +/- 0.7 micromole N2O m-2 d-1. The region studied at 85 degrees W (65.28 degrees S to 70.32 degrees S) revealed source and sink areas which were largely determined by the changing physical hydrography, so that overall there was a small net negative flux of between -0.06 +/- 0.9 and -0.09 +/- 1.4 micromole N2O m-2 d-1. Funding: The work was supported by NERC funding to the Plymouth Marine Laboratory, the British Antarctic Survey and from the U.K. Biogeochemical Flux Study (BOFS).

Comparable deep-water benthos datasets collected by epibenthic sledges (EBS) with an epibenthic and a suprabenthic netsampler in the Atlantic Ocean have been gathered since 2006. They were collected during the international research expeditions: ANDEEP-SYSTCO II, BIOPEARL I, DIVA1-3, IceAGE1-3&RR, IceDIVA1,2, JR275 and Vema-TRANSIT. While EBS diversity data at high taxon level were published for ANDEEP_SYSTCO II, DIVA1-3 and Vema-TRANSIT, unpublished diversity data for BIOPEARL I, IceAGE1-3&RR, IceDIVA1, 2 and JR275 came from sample databases at DZMB Senckenberg and British Antarctic Survey, and are published here for the first time. In total, diversity data for 143 EBS deployments from 13 expeditions were available for analyses based on identification on 50 taxon levels, including phyla, subphyla, classes and orders. During all 13 expeditions EBS with an epibenthic and a suprabenthic netsampler following sampler sizes and height , enabling comparability of samples. This type of EBS was a suitable device for sampling small benthic fauna on and above the seabed, including macrofauna and small-sized megafauna. We analyse pan-Atlantic benthic data from a range (119m - 8338m) of depths. For the pan-Atlantic analyses we defined seven regions to pool EBS locations based on their position North and South of the Equator and to the mid-Atlantic Ridge (MAR): East and West of the MAR, the Vema Fracture Zone as a gap in the MAR, the Southern Ocean south of the MAR and the Puerto Rico Trench as a deep-sea trench. In this study we included data for 41 higher taxa of the initially separated 50 taxa ranging from phyla to orders. The environmental parameters for this study were provided by Bio-ORACLE, which identifies mean values for different physical and chemical variables over a 14 year time period through a combination of satellite and in-situ measurements (2000 - 2014), at a resolution of 5 arcmin. 4 multivariate analyses (principal components analysis, analysis of similarities, similarity of percentages and BioEnv BEST) were carried out on standardised abundances using PRIMER software, the results and parameters of which are presented in this dataset. Funding over the years for the sample collection and analyses was provided by multiple NERC grants and international grants. Katrin Linse, Peter Enderlein and Huw J. Griffiths were part of the British Antarctic Survey Polar Science for Planet Earth Programme funded by The Natural Environment Research Council (NERC) [NC-Science] and included the funding for the RSS James Clark Ross expeditions BIOPEARL I and JR275. This study was directly funded by the IceAGE_RR and IceDIVA grants by the German Science Foundation (DFG) and Bundesministerium fur Bildung und Forschung (BMBF) under grant numbers MSM75 (MerMet17-5), SO280 and SO286 to PIs Saskia Brix, James Taylor and Katrin Linse. Funding for previous expeditions that provided data were: IceAGE1-3, BR3843-3-1& 4-1, & SO276 (MerMet17-6). James Taylor and Karlotta Kurzel were supported via DFG grant GPF 20-3_087 as part of the IceDiva project 2021 - 2022 by DFG. Anne-Nina Lorz was funded by the German Science Foundation Project IceAGE Amphipoda, LO2543/1-1. Additionally, Angelika Brandt was granted funding (SO 237, Forderziffer 03G0237A) by the Bauer Foundation for the VEMA-Transit project. Inmaculada Frutos was supported through the junior research group''Vema TRANSIT. Puerto Rico Trench, Vema Fracture Zone and Abyssal Atlantic Biodiversity Study'' as part of the project ''Biodiversitatnachhaltige Ressourcennutzun'' (Aktenzeichen T237/25054/).