The dataset comprises 17 hydrographic data profiles, collected by a conductivity-temperature-depth (CTD) sensor package, from across the North East Atlantic Ocean (limit 40W) area specifically around Cape Verde and to the north east of the Canary Islands. The data were collected from February to April of 1972. A complete list of all data parameters are described by the SeaDataNet Parameter Discovery Vocabulary (PDV) keywords assigned in this metadata record. The data were collected by the National Institute of Oceanography.

Multibeam bathymetry data were collected in the Clarion-Clipperton Zone (CCZ), Northeast Pacific Ocean, using a hull-mounted Kongsberg EM122 multibeam echosounder during RRS James Cook Cruise JC241 from 06/02/2023 to 25/03/2023, and JC257 from 08/02/2024 to 19/03/2024. Data acquisition began upon exiting the Costa Rican Econoic Exclusion Zone (EEZ), suspended within the Clipperton Island EEZ, and resumed upon exiting the Clipperton Island EEZ. Data were then acquired throughout the CCZ. This suspension was repeated on the return journey. The data were recorded using Kongsberg’s Seafloor Information System (SIS) in .all format, and CTD and model-derived sound velocity profiles were subsequently applied. The data were manually cleaned using swath and subset editors in CARIS HIPS and SIPS software version 10.4. A zero tide file was also applied. The data were collected to obtain a better insight in the biodiversity patterns and benthic habitat distributions within the CCZ, by scientists from the National Oceanography Centre, Southampton, UK as part of the NERC-funded Seabed Mining And Resilience To EXperimental impact (SMARTEX) project (NE/T003537/1).

This multi-decadal time series initially contains water current and temperature data from a single, near bottom instrument. A second, shallower instrument recording the same parameters was subsequently added after several years of successful operation. Conductivity data are similarly integrated into the time series after a further period of operation. The data are typically at hourly resolution. The mooring is situated in the Tiree Passage, between the Isles of Mull and Coll, off the west coast of Scotland. The specific site chosen was where the passage is at its narrowest (10 km), mid-way between the coasts of the two Isles. The mooring site is in water depths of approximately 45 m. Mooring activity began in June 1981 and consisted of a single RCM current meter placed 11 m above the seabed. The mooring design was modified to incorporate a second RCM current meter at 22 m above the seabed from November 1987. Aanderaa conductivity sensors were added at the two depths in 1993, with MicroCAT conductivity sensors being incorporated in 2002. There are some gaps in the record, most noticeably between January 2000 and May 2002, a period when the observations were temporarily suspended. Fishing damage has generated smaller gaps in the data set over the years. This region was chosen as a site for long term monitoring after radiocaesium studies showed that the major part of the water carried northwards from the North Channel in the Scottish coastal current passes between Mull and Coll. The mooring provides data for comparison with tracer studies and for an examination of the roles of wind forcing and buoyancy contributions to the coastal current. Tiree Passage mooring work is led by Colin Griffiths at the Scottish Association for Marine Science (SAMS).

Calanus hyperboreus dominates the copepod biomass in the high Arctic. It forms an important intermediate trophic level in the Central Arctic food web, grazing on algae and protists and serving as prey for a large range of other zooplankton, fish and seabirds. Their unique lipids (20:1, 22:1 fatty acids and fatty alcohols) can be traced within the Arctic megafauna from seals to whales and polar bears, as these energy-rich lipids are crucial body reserves for the dark season. During the MOSAiC expedition in the Central Arctic Ocean (CAO, 2019-2020), C. hyperboreus adult females (AF) and subadult copepodites stages (CV) were sampled weekly to fortnightly. A range of nets were used to sample either horizontally underneath the sea ice or vertically from maximum 2000 m through the water column. Onboard, ~10 AF and ~20 CV of C. hyperboreus were sorted from each catch, photographed, rinsed with freshwater to remove salt and frozen at -80C for subsequent analysis of their total dry mass (DM), lipid content and a suite of trophic markers, including bulk stable isotopes (BSI), phytosterols (PS), total fatty acids (TFA), total fatty alcohols (TFAlc), and highly-branched isoprenoids (HBI). During the time of their seasonal descent at the end of summer, vertical sampling of C. hyperboreus was intensified and additional parameters were analysed, e.g. the FA and FAlc composition of their storage lipids (neutral lipids, NLFA, NLFAlc) and membrane lipids (polar lipids, PLFA, PLFAlc), the carbon isotopic composition of key FA and FAlc (CSIA-FA; CSIA-FAlc), and the tissue density. By combining this array of trophic markers, valuable information about the body conditions and feeding history of these copepods can be linked to their life cycle and vertical distribution. The initial separation of the various trophic markers was carried out at the University of Plymouth. After estimating the total DM, subsamples for BSI were sent to the Littoral, Environment and Societies Joint Research Unit stable isotope facility (CNRS - University of La Rochelle, France) for analysis. Three internal standards were added to the samples used for lipid analysis to quantify the TFA, TFAlc, PS and HBI content. As a first step, the total lipid content of the animals was extracted in dichloromethane : methanol. The lipid samples were split into two equal subsamples, one was sent to the Alfred-Wegener-Institute (AWI) in Bremerhaven/Germany for FA and FAlc analyses and the second was used for PS and HBI analyses in Plymouth. This dataset is linked to a manuscript that compares the trophic marker composition of C. hyperboreus from the surface vs. deep ocean to understand drivers, benefits, and risks of their seasonal migration in the CAO. The manuscript focusses mainly on the copepod descent in late summer and the changes in body conditions and trophic marker composition over the winter months. Contributions by KS were funded by the UK's Natural Environment Research Council MOSAiC Thematic project SYM-PEL: "Quantifying the contribution of sympagic versus pelagic diatoms to Arctic food webs and biogeochemical fluxes: application of source-specific highly branched isoprenoid biomarkers" (NE/S002502/1). CJA, RGC, CEG, KMS and RJ were funded by the US National Science Foundation Office of Polar Programs (OPP-1824447 and OPP-1824414).

The dataset contains 3 data files. Firstly, it contains one set of stable isotope compositions expressed as delta13C, d15N, d34S values recovered from fish muscle from a variety of species captured in September 2019 across the Barents Sea as part of the joint IMR-PINRO Barents Sea Ecosystem Survey. Samples were collected by Dr Matthew Cobain and Dr Kim Vane, and isotope data analysed at the university of Southampton. A second dataset contains delta13C and delta18O compositions of fish otolith carbonate recovered from a subset of the same fish. A final sheet contains the full metadata associated with each fish sampled on the survey. All samples were processed by Dr Matthew Cobain or Prof Clive Trueman and stable isotope values determined at the University of Southampton. Funding: Project was funded under the NERC Changing Arctic Ocean project, Coldifsh (NE/R012520/1).

Polar - tropical biodiversity comparisons are becoming essential in order to investigate fully the origin and maintenance of the larger scale patterns of life on Earth. Although many polar data are now readily to hand it is often more difficult to locate accurate and up to date tropical datasets to use in direct comparisons. This dataset represents an attempt to rectify this imbalance using two of the largest clades in shallow tropical seas at the present day. The data were obtained from primary published literature which is fully referenced below and in the companion research paper to this dataset. They relate to nine regional localities which stretch across the tropical realm from the Indo-West Pacific to the Americas. For each locality there is a full species list, with each species being assigned to both a genus and family. The latest taxonomic references have been used to ensure that all these lists are based on current biological nomenclature. Funding: Partly from NERC grant NE/I005803/1 Partly from BAS core funds

This dataset comprises conductivity, temperature and depth (CTD) casts which were deployed around Rothera Point, Adelaide Island on the West Antarctic Peninsula between November 2023 and February 2024. Data were captured as part of a biodiversity survey on an area to the north of Rothera Research station. Operations were conducted off small boats and casts sampled shallow waters between 10m and 60m in depth. Data comprises parameters such as pressure, salinity, density, turbidity and more in addition to conductivity, temperature and depth. Data were collected by personnel at BAS, funded by the Antarctic Infrastructure Modernisation Project (AIMP) Runway 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).

This dataset contains gridded spatial predictions of the distribution and density of Antarctic krill (Euphausia superba) in the South Scotia Sea, specifically within Subarea 48.2 of the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR). Both year-specific and decadal mean predictions are provided across years 2011-2020. All predictions were generated from a two-part hurdle model which used input data from (i) a spatially and temporally consistent acoustic krill survey around the South Orkney Islands and (ii) year-specific environmental covariates. The first hurdle model component was a binomial Generalized Additive Model (GAM) fitted to binary presence-absence krill data which predicts the probability of krill presence. The second component was a Gaussian GAM fitted to non-zero krill data which predicts krill density. Finally, these components were combined to identify where krill were both likely to be present and occur at high densities. Full model details are given in the associated publication. This dataset provides the spatial predictions generated from the binomial GAM, Gaussian GAM, and their combined product. Funding: PNT, SF and JJF were supported by the British Antarctic Survey's National Capability Antarctic Logistics and Infrastructure programme CONSEC, supported by the Natural Environment Research Council, a part of UK Research and Innovation.; VW-E and JJF were supported by the Pew Charitable Trusts under grant PA00034295. The South Orkney Islands acoustic trawl survey is part of the ongoing Norwegian Institute of Marine Research (IMR) project KRILL (p.no. 14246), which is supported by the Norwegian Research Council (NFR grant 222798), the Norwegian Ministry of Foreign Affairs, and IMR.

During the JR19002 Icebergs 3 cruise, samples from the surface seawater were collected from Zodiacs. Samples were collected with the motivation of determining the impact of retreating glaciers upon the surface ocean, such as the hydrography and biogeochemical composition of the surface ocean. Three main sites were visited during JR19002 from south to north: Marian Cove, Maxwell Bay, King George Island; Borgen Bay, Anvers Island; and Sheldon Cove, Ryder Bay, Adelaide Island. Small boat traversed each bay, collecting particulate and dissolved seawater samples. Parameters collected and determined include: stable oxygen isotopes, salinity, dissolved macronutrients, dissolved and particulate metals, radium and thorium activity. Funding: NERC grants, NE/P017630/1 (Dr Amber Annett) and NE/P003060/1 (Professor David Barnes).