Temperature data were collected from a tidepool at Rothera Point, Antarctica every two minutes from February 1999 to May 2000, with the aim of documenting tidal, diurnal and seasonal variability.

Marine debris washed up on beaches on Goudier Island has been recorded since 2014. Surveys are conducted on a monthly basis when the station is occupied during the summer season. This data contributes to the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) Marine Debris programme.

The data include size, sex, location and morphological measurements and of Muraenolepis specimens included in Fitzcharles et al. (2021). The morphometric data were primarily collected from fish captured during South Georgia Groundfish Surveys in 2003, 2004 and 2005, with additional data obtained from type specimens and extracted from published descriptions of Muraenolepididae. For genetic studies, tissue samples from the South Georgia specimens were supplemented by additional tissue samples from Muraenolepis in other parts of the Southern Ocean. Source, location and depth of capture are included for all specimens that were sequenced, together with sequence Accession Numbers (to the DNA Database of Japan) for Cox 1 and 16S rRNA sequences. The work was primarily funded by the Government of South Georgia & the South Sandwich Islands and was a component part of Elaine Fitzcharles'' PhD (University of St Andrews).

An opportunistic marine mammal survey through the Atlantic Ocean between the UK and Antarctica was undertaken in November and December 2020. The RRS James Clark Ross, was used to transfer cargo and personnel for the British Antarctic Survey (BAS) from the UK to Rothera Research Station, Antarctica for the start of the 2020/2021 summer season. The transit and station relief included stops at King Edward Point and Bird Island, South Georgia, Falkland Islands and Signy Research Station, South Orkney Islands. The journey took a total of 48 days. Two JNCC marine mammal observers were on-board as well as other dedicated observers. Marine mammal observations were made as opportunistic sightings and recorded along with geographical position and other metadata. This transit and subsequent survey was unique in its passage as few vessels journey down the centre of the North and South Atlantic and continue on down the Western Antarctic Peninsula. British Antarctic Survey will continue to make this journey twice a year and it could provide a platform for an annual marine mammal survey of the entire Atlantic Ocean.

Macrozooplankton and nekton were collected with a Rectangular Midwater Trawl 25 (RMT25) over several visits to the sustained observation location P3 (52.70 S, 40.26 W) in the northern Scotia Sea during November and December 2017. The work was carried out as part of the NERC Large Grant, COMICS (Controls on Mesopelagic Interior Carbon) on board the RRS Discovery (cruise DY086). The RMT25 net hauls sampled between 10 and 500 m depth, with the water column divided into 2 depth intervals (10-250 m and 250-500 m). A total of 6 hauls were obtained during 3 separate visits to station P3, each visit comprising a pair of hauls, of which one was carried out in nominal daytime and the other in nominal nighttime. Catches were immediately sorted on board and identified to the lowest taxonomic level feasible. Subsamples of the catches were retained, principally for subsequent biochemical and physiological analyses. In total, 777 fish were caught, belonging to at least 23 species, with catches dominated by the myctophids Krefftichthys anderssoni, Gymnoscopelus braueri, Electrona antarctica and Protomyctophum tenesoni. The water column below 250m was dominated by Bathylagus spp. Temperate myctophid species, such as Protomyctophum parallelum and Protomyctophum andreyeshevi were also caught in small numbers. With regards macrozooplankton, the 250m-500m depth interval was dominated by the jellyfish, Atolla and Periphylla. The tunicate Salpa thompsoni and the euphausiids Euphausia triacantha and Thysanoessa spp. were also relatively abundant. Jellyfish still dominated catches in shallower waters (250m-10m), closely followed by euphausiids and Salpa thompsoni and chaetognaths. Themisto gaudichaudii and Parandania boecki were the most numerous amphipod species caught. Decapods were only caught in the deeper depth interval, both day and night.

This dataset includes stable nitrogen isotopes of bulk tissue (delta-15Nbulk) and compound specific stable nitrogen isotopes on amino acids (delta-15NAA) measured in harp seal (Pagophilus groenlandicus) teeth from Southern Barents Sea, Greenland Sea, Northwest Atlantic, and ringed seal (Pusa hispida) muscles from Canadian Arctic Archipelago and Baffin Island, in the Arctic and sub-Arctic. Teeth of harp seals from the Northwest Atlantic (n=48) were taken from archives in Fisheries and Oceans Canada (DFO) St John''s, Canada from 1979 to 2016. Teeth of harp seals from the Barents Sea (n=72) and Greenland Sea (n=55) were taken from archives of the Institute of Marine Research (IMR), Norway, from 1963 to 2018 and 1953 to 2014, respectively. Muscle tissue from ringed seals were opportunistically sampled as part of Inuit subsistence harvests. Samples from the CAA were collected in Resolute from 1992 to 2016 (n=66). Muscle samples from the Baffin Bay were collected in Pangirtung from 1990 to 2016 (n=39). The seal samples were collected as part of Norwegian commercial sealing and student field courses from the University of Tromso in Norway (Barents Sea and Greenland Sea) and the Inuit subsistence and commercial harvests in Canada (Northwest Atlantic, Baffin Island, Canadian Archipelago). Analyses of delta-15Nbulk and delta-15NAA of seal tissue were carried out at the Liverpool Isotopes for Environmental Research laboratory, University of Liverpool. Results are reported here in standard delta-notation (per mille) relative to atmospheric N2. This work resulted from the ARISE project (NE/P006035/1 and NE/P006310/1), as part of the Changing Arctic Ocean programme, funded by the UKRI Natural Environment Research Council (NERC).

Water column acoustic data collected in the Amundsen and Bellingshausen Seas (from 2008-02-26 to 2008-04-10) during cruise JR179. Multi-frequency (38,120 and 200 kHz) acoustic data were collected using a Simrad EK60 echo sounder. The dataset comprises of calibrated and processed 38 kHz volume backscattering strength (Sv, dB re 1m-1). Data processing was undertaken using Echoview and Matlab. Processed netCDF data files are made available as part of the NERC Southern Ocean Network of Acoustics (SONA) and the EU MESOPP project.

Water column acoustic data collected in the Scotia Sea (from 2009-12-23 to 2009-12-30) during cruise JR228. Multi-frequency (38,120 and 200 kHz) acoustic data were collected using a Simrad EK60 echo sounder. The dataset comprises of calibrated and processed 38 kHz volume backscattering strength (Sv, dB re 1m-1). Data processing was undertaken using Echoview and Matlab. Processed netCDF data files are made available as part of the NERC Southern Ocean Network of Acoustics (SONA) and the EU MESOPP project.

This dataset contains occurrence records and associated metadata for the zooplankton species Calanus finmarchicus that were compiled from multiple open access databases. A file containing the corresponding background points is provided, along with gridded environmental variables for each season (Jan-Feb-Mar, Apr-May-Jun, Jul-Aug-Sep, Oct-Nov-Dec) and era (1955-1984, 1985-2017) that were assessed in this study. Together these data were used as input files for the MaxEnt ecological niche model within the peer reviewed article: Freer JJ, Daase, M, Tarling GA, (2021) Modelling the biogeographic boundary shift of Calanus finmarchicus reveals drivers of Arctic Atlantification by subarctic zooplankton, Global Change Biology. Finally, an R Markdown document is provided to enable data users to replicate the model optimisation and prediction steps using the input data files within this repository. Funding was provided by: UKRI Natural Environment Research Council (NERC): DIAPOD (NE/P006213/1), NERC and the German Federal Ministry of Education and Research (BMBF): CHASE (NE/R012687/1), Norwegian Research Council: Deep Impact project (300333).

Cetacean sightings in South Georgia and South Sandwich Islands waters, made by a team of four professional marine mammal observers during the British Antarctic Survey CCAMLR synoptic krill survey on the RRS Discovery (DY098), January and February 2019. The latitude and longitude of each sighting, the identified species, bearing and distance from the vessel, and estimated group size are provided. These data have been used by BAS to estimate (i) humpback whale and (ii) baleen whale abundance in South Georgia and South Sandwich Islands waters in 2019. Funding was provided by the Foreign, Commonwealth and Development Office, as part of the Overseas Territories Blue Belt programme, as well as the South Georgia Heritage Trust, Friends of South Georgia Island and Darwin PLUS award DPLUS057.