KRILLBASE is a data rescue and compilation project which aims to improve the availability of information on two of the Southern Ocean's most important zooplankton taxa: Antarctic krill (Euphausia superba) and salps (Family Salpidae). In 2016, the project released a database of information from 15,194 scientific net hauls, collected between 1926 and 2016 by scientists from ten countries. These data, on the density of Antarctic krill and salps, provide a resource for analysing the distribution and abundance of these taxa throughout the Southern Ocean, to support ecological and biogeochemical research as well as fisheries management and conservation. The data are available as a downloadable csv files and via a seachable web interface. Each row of the main data table represents either a net haul or a composite of several net hauls. The columns describe searchable and filterable sampling and environmental information as well as the krill and salp density. The krill data are presented as both the observed density (NUMBER_OF_KRILL_UNDER_1M2, no.m-2) and the density standardised to a single, relatively efficient sampling method (STANDARDISED_KRILL_UNDER_1M2, no.m-2). The salp data are presented as observed density for all species combined, where an individual can be either a solitary oozoid or a member of an aggregate chain (NUMBER_OF_SALPS_UNDER_1M2, no.m-2). 12,758 of the net hauls in the database include krill data, 9,726 include salp data. 7,295 of the net hauls include both krill and salp data. For hauls where data for either salps or krill were not available the relevant field is blank. The RECORD_TYPE column distinguishes between four types of record and we emphasise that every analysis of the data should first screen on this field to avoid using the same data twice. Most records are labelled "haul", and these result from a single net sampling the water column at a specific station. Others, labelled "stratified pooled haul", are the combined result of several (typically three) stratified hauls (labelled "stratified haul") sampling different parts of the water column. A small number of records, labelled "survey mean" represent the arithmetic mean densities from multiple stations as this was the only recoverable information from the relevant surveys, which were mainly conducted in the 1980s. The dataset is fully described in the following publication which should be cited in published analyses of these data: Atkinson A, Hill SL, Pakhomov E, Siegel V, Anadon R, Chiba S, Daly KL, Downie R, Fielding S, Fretwell P, Gerrish L, Hosie GW, Jessopp MJ, Kawaguchi S, Krafft BA, Loeb V, Nishikawa J, Peat HJ, Reiss CS, Ross RM, Langdon B Quetin, Schmidt K, Steinberg DK, Subramaniam RC, Tarling GA, Ward P (2017) KRILLBASE: a circumpolar database of Antarctic krill and salp numerical densities, 1926-2016. Earth Syst. Sci. Data, 9: 193-210 (doi:10.5194/essd-9-193-2017)

Quantification of interactive effects of ocean warming and ocean acidification based on near-future climate change projections on morphometrics and oocyte size of benthic invertebrates (the bivalves Astarte crenata and Bathyarca glacialis) from the Western Barents Sea. Supported by The Changing Arctic Ocean Seafloor (ChAOS) - how changing sea ice conditions impact biological communities, biogeochemical processes and ecosystems project (NE/N015894/1 and NE/P006426/1, 2017-2021), Natural Environment Research Council (NERC) in the UK.

Multiple arrays with heated panels (1 degree Celsius and 2 degrees Celsius above ambient temperature and non-heated) were deployed subtidally in the Menai Strait for a period of 13 months from the summer of 2015 to the summer of 2016. The effect of temperature on species composition of the assemblage, seasonal effects and on the growth rates of one of the main colonisers, the polychaete Spirobranchus triqueter was assessed. Underwater photographs of the panels were taken regularly over the course of 13 months. The images were merged into a single image using Photoshop CS5. The growth rate of the main coloniser Spirobranchus triqueter and species diversity and percentage of the panel community were measured using Fiji(ImageJ) and Rstudio. This project was funded by NERC: reference NE/J007501/1 "Effects of warming on recruitment and marine benthic community development in Antarctica".

In 2017, the RV METEOR M134 expedition investigated macrobenthic assemblages associated with methane seeps on the South Georgia continental shelf. Six shelf troughs with active methane seepage were sampled to assess species richness, abundance, and environmental conditions. Data were collected from eleven shelf stations, with species richness ranging from 19 to 51 species and abundances from 3,303 to 30,326 individuals per square meter. A total of 103 species were identified, with arthropods (primarily crustaceans) and annelids comprising most of the species richness. Environmental data include methane and sulfate flux, hydrogen sulfide concentrations, and sediment geochemistry. Seep assemblage data is combined with data from non-seep benthic communities from other expeditions.The dataset provides: 1) South Georgia methane seep station locations and environmental data. 2) Macrobenthic species absolute and normalized abundances at seep sites. 3) A combination of seep assemblages with non-seep benthic communities from other expeditions. Funding: The fieldwork for this study, was supported by the Deutsche Forschungsgemeinschaft (DFG) in the framework of the priority programme 'Antarctic Research with comparative investigations in Arctic ice areas' (project-id 40464014) and within the DFG-Research Center/Cluster of Excellence EXC 309 'The Ocean in the Earth System' (project-id 49926684). The expedition, titled 'Emissions of free gas around South Georgia: distribution, quantification, and sources for methane ebullition sites in sub-Antarctic waters,' was supported by MARUM - Center for Marine Environmental Sciences, Research Faculty University of Bremen, and the University of Bremen. Additional support came from the Helmholtz Association (Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven). The cruise was funded by the German Research Foundation (DFG) and the Federal Ministry of Education and Research (BMBF). Katrin Linse is part of the British Antarctic Survey Polar Science for Planet Earth Programme (NC Science), funded by the Natural Environment Research Council (NERC). Studies around South Georgia were conducted under permit RAP 129/2016 (M134) issued by the Foreign & Commonwealth Office, UK. Macrobenthic faunal sorting was supported by the Natural Environment Research Council through a DEI Internship for Madeline PBC Anderson (via the NERC Diversity, Equity and Inclusion engagement funding) and an IAPETUS2 PhD studentship held by Madeline PBC Anderson (grant reference NE/S007431/1).

Three species of Antarctic marine invertebrate: Nacella concinna (limpet), Paraceradocus miersi (crustacean) and Sterechinus neumayeri (urchin) were subjected to three different rates of warming and a two month acclimation trial at 2 degrees Celsius. The rates of warming were 1 degree Celsius per hour, 1 degree Celsius per day and 1 degree Celsius per 3 days. Animals were evaluated to determine whether there was a universal stress response at the cellular level. Funding was provided from the BAS National Capability Grant, funded by the UKRI Natural Environment Research Council (NERC).

These data are gonad index (gonad mass/total animal mass) and egg size measurements for two Antarctic marine invertebrates, the starfish Odontaster validus and the brittle star Ophionotus victoriae. Data are for samples hand-collected monthly, where weather permits, by scuba divers from sites near the British Antarctic Survey's research station at Rothera Point, Adelaide Island. Samples were first collected in 1997 and have continued for 19 years to 2015.

This is a physiological dataset for the Southern Patagonian limpet, Nacella deaurata. The limpets were collected from 2-6m depth in the Straits of Magellan near to Punta Arenas (53.164 S, 70.917 W) between Nov and the end of Jan 2018-19. A 2 month feeding experiment maintained N. deaurata at 1,4,8,11 and 14 degree Celsius for 2 months. Ingestion rate, absorption efficiency, absorption rate, oxygen consumption (uptake), scope for growth and mortality were measured. The thermal reaction norm for duration tenacity of field fresh subtidal and intertidal limpets, as well as subtidal limpets that were incubated at 8 degree Celsius for 2 months was investigated. The thermal reaction norm of radula scraping rates of field fresh limpets was measured. This work was funded by the Center FONDAP-IDEAL 15150003, ANID Chile and NERC core funding to the British Antarctic Survey.

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).

Data presented are mean biomass values of samples of Aequiyoldia eightsii larvae collected between June and September 1990 using a 100 micron plankton net deployed from a small inflatable boat from Factory Cove, Signy Island, South Orkney Islands. Samples were returned to the laboratory and larvae removed from bulk samples by eye using a Wild M5 field microscope. Numbers in samples were between 8 and 40, but predominantly 15 or 20. Sampling, sorting and later processing was conducted by Jeremy Colman. The data were used to evaluate the development rate and duration of the pelagic larval phase of this sediment dwelling Antarctic bivalve mollusc. Data analyses were conducted in MINITAB. Funding source: The work was fully supported by core funds to the British Antarctic Survey from the Natural Environment Research council, UK

The KRILLBASE-length frequency database comprises individual length measurements of 613487 Euphausia superba from 6470 scientific net hauls. Some of these individually-measured krill have additional information on their sex and maturity stage. Most of these E. superba are postlarvae, but some of the hauls include small (< 20 mm) krill which likely include furcilia larvae as well as juveniles. Much of these data were compiled at British Antarctic Survey in 2007 by Mark Jessopp, with additional compilation by Angus Atkinson, Catherine Brewster and Natalie Ensor, and later data checking by Angus Atkinson with Helen Peat. The circumpolar distribution of records is illustrated in the file KRILLBASE_LF_DISTRIBUTION that is available along with this dataset. Examples of uses of KRILLBASE-length frequency are in Atkinson et al. (2009), Tarling et al. (2016), Perry et al. (2019) and Atkinson et al. (2019). The KRILLBASE-length frequency records were provided by contributing authors of the database or transcribed from the literature or from other institutional databases. At the time of data compilation, data from commercial-size large mesh trawls and from the commercial fishery was also transcribed, providing valuable information on the larger krill caught by these nets. These data are not included in this current KRILLBASE-length frequency database version, because of the difficulty in comparing them with the finer mesh scientific nets compiled here, and because length and population structure are also available in more complete form from CCAMLR. The KRILLBASE-length frequency database forms a complementary database to the KRILLBASE-abundance database (doi:10.5285/8b00a915-94e3-4a04-a903-dd4956346439), which compiles the abundance of Euphausia superba and salps in the Southern Ocean (Atkinson et al 2017). Both databases are multi-national, circumpolar compilations of net samples spanning years 1926 to 2016. The KRILLBASE-length frequency database uses some of the stations as KRILLBASE-abundance but also additional ones from targeted hauls or horizontal hauls.