Dataset includes 2 sets of data on Streptophyte glacier algal photophysiology as assessed through Pulse Amplitude Modulation (PAM) fluorometry of communities sampled from the surface of the Greenland Ice Sheet during summer 2024. The first set of responses are of communities sampled from fully exposed versus shaded regions of ice measured through rapid light curve techniques after 5 minutes of dark adaptation. The other set of responses are the same surface ice samples measured after 24 hours of dark-adaptation and melt. Analysis of rapid light curve datasets to highlight fine-scale heterogeneity in glacier algal in-situ photophysiology are published in Williamson et al. (2024). This marks the first time an in-situ method has been developed to map glacier algal photophysiology relative to dominant abiotic stressors. Funding provided by the following: Leverhulme Trust "iDAPT" project RPG2020-199 National Environmental Research Council "CASP-ICE" project NE/Y002636/1 ERC Synergy "Deep Purple" project 856416

The abundance, photophysiology, pigmentation, bio-optical properties, cellular energy balance and instantaneous radiative forcing of glacier algal assemblages from the surface of the Greenland Ice Sheet (GrIS) are quantified throughout the 2016 ablation season. The effects of assemblages on ice surface albedo are further derived using a newly developed model of glacier algal blooms for the GrIS, radiative transfer modelling using BioSNICAR-GO, and comparisons to MODIS broadband albedo observations over the same season. Data represent a composite of in-situ observations, in-situ incubations studies, laboratory analyses, modelling and remote sensing. All in -situ work was performed at site S6 of the K-Transect in the southwestern GrIS ablation zone as part of the Black and Bloom project. Funding was provided by the NERC ''Black and Bloom'' grant NE/M021025/1 and the Marie Sklodowska-Curie grant agreement No 675546.

This dataset consists of 75 destructive ice surface samples for which glacier algae cell counts were undertaken. The sample locations were distributed randomly over a 250 X 250 m area. Funding was provided by the NERC standard grant NE/M021025/1.

Data were collected as part of the DiatomARCTIC project during the Multidisciplinary Arctic Program - Last Ice sampling campaign (82.576 N 62.471 W), 7-23 May, 2018. The bottom 10 cm of ice samples were collected during this time from neighbouring first-year and multi-year sea ice floes, from which the following parameters were determined: chlorophyll a, exopolymeric substances, ice algal taxonomic composition, oxygen-based net community production and bulk-ice nitrate, nitrite and phosphate concentrations. All samples were melted without dilution and were processed by K Campbell. This work is a contribution to the Diatom ARCTIC project (NE/R012849/1; 03F0810A), part of the Changing Arctic Ocean program, jointly funded by the UKRI Natural Environment Research Council and the German Federal Ministry of Education (BMBF) and Fisheries and Oceans Canada (DFO) Science and the Marine Productivity Laboratory Program. The Multidisciplinary Arctic Program (MAP) - Last Ice is funded by Fisheries and Oceans Canada (DFO) Science in support of Tuvaijuittuq Marine Protected Area (MPA). Additional support was provided by Polar Continental Shelf Program (PCSP, Project 10718) and the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Funds to CM and CHSR.

This dataset is a sequential list of all the terrestrial snow and ice samples taken at Robert Island, Antarctica from January 2023 to March 2023. Sample date, location, bloom colour and what the sample was subsequently used for (metabolomics, pigment, DNA, DOC, FTIR, CN), along with cell counts is provided. Cell counts and biometric measurements of Ancylonema are included in the dataset. The samples were taken by small 15ml or 50ml plastic tube sampling in the snow pack or on the icecap hard ice. This was to study the habitat and ecosystem progression over the season and linking this to other satellite or drone or vegetation data. A remote sensing output (red snow algae vector for Robert Island) was also produced. The expedition and sampling was carried out by Matthew Davey (PI), Alex Thomson, Andrew Gray, Hannah Moulton, Charlotte Walshaw with support from INACH, Chile and BAS. This was part of a wider project with Claudia Colesie, Naomi Thomas, Peter Convey, Alison G. Smith, Peter Fretwell, Lloyd Peck. Samples were transferred to UK (SAMS) for further analysis. This project was funded by Standard NERC References: NE/V000764/1 and NE/V000896/1. The past, present and future of snow algae in Antarctica: a threatened terrestrial ecosystem?

A seasonal cycle of the FA composition of particulate organic matter from surface waters, Chlorophyll-a maximum layer and bottom sea ice, sampled during the MOSAiC expedition in the Central Arctic Ocean (2019-2020), suggests the importance of phylogenetic and environmental drivers. To improve our understanding of these different drivers, we conducted culture experiments with 32 cold-water algal strains where temperature, light intensity, and nutrient supply were manipulated individually or in combination. The culture experiments were carried out at the Culture Collection of Algae and Protozoa (CCAP; Oban, Scotland), the Roscoff Culture Collection (RCC; Roscoff, France) and the Alfred-Wegener-Institute-Helmholtz-Centre for Polar and Marine Research (AWI; Bremerhaven, Germany). The strains were part of the culture collections, had been isolated in the Arctic (25 strains), Southern Ocean (2 strains) or North Atlantic (5 strains), and included diatoms, chlorophytes, haptophytes, cryptophytes, chrysophytes, dinoflagellates and cyanobacteria. Some of the species are Arctic sea ice diatoms (e.g. Nitzschia frigida, Attheya spp.) or pelagic diatoms (e.g. Thalassiosira gravida), while others are non-diatom species that are becoming increasingly prominent in the Arctic, e.g. the coccolithophore Emiliania huxleyi (synonym Gephyrocapsa huxleyi), the prymnesiophyte Phaeocystis pouchetii, the chlorophyte Micromonas spp. and the cyanobacterium Synechococcus spp.. The experiments can be divided into three groups: First, those that tested a low light-low temperature setting, second, those that tested a low light-low temperature and a higher light-higher temperature setting and, third, those that tested the effect of nutrient (nitrate, phosphate and silicate) shortage in combination with low and high light intensity. The first set of experiments was conducted with all 32 strains, the second set with all strains grown at CCAP and AWI, and the third set focuses on the keystone under-ice diatom Melosira arctica. The experiments were run for 4-7 weeks to accumulate sufficient biomass for biomarker extractions (FA and sterols), C:N analysis and light-microscopy of cell size and cell concentration. At the end of the experiments, the algae were filtered onto GF/F filters and deep frozen until analysis. After addition of internal standards for FA and sterols, the filters were saponified with KOH. Thereafter, non-saponifiable lipids (sterols) were extracted with hexane and purified by open column chromatography on silica gel. FA were obtained by adding concentrated HCl to the saponified solution and re-extracted with hexane. Samples were converted into fatty acid methyl esters (FAME) and analysed using an Agilent 6890N gas chromatograph with FID detector. The Clarity chromatography software system (DataApex, Czech Republic) was used for chromatogram data evaluation. FAME were quantified via the internal standard, Tricosanoic acid methyl ester (23:0) (Supelco, Germany) to provide the total amount of FA (TFA) per filter. These FA datasets of cultured algae are presented in a manuscript together with the FA pattern seen in sea ice- and water column POM in the CAO during the MOSAiC expedition and in previously published data from Arctic shelf regions. The manuscript focusses mainly on two important long-chain omega-3 FA (eicosapentaenoic acid and docosahexaenoic acid) that are considered essential for the nutrition of higher trophic levels, including humans, and their production to decline with global temperature rise. 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). CRM was funded by the NERC National Capability Services and Facilities Programme (NE/R017050/1).

This database contains information on the herbarium specimens held in the herbarium of the British Antarctic Survey (international code AAS) as well as information about specimens collected in the Antarctic and sub-Antarctic and held in other world herbaria. There are over 70 000 records, predominantly of mosses and lichens, but also of vascular plants, ferns, fungi and algae collected in Antarctic and sub-Antarctic regions as well as some from surrounding continents, particularly South America. The collection from South Georgia And The South Sandwich Islands started in 1775 and from Antarctica in 1834. Documents relating to the Herbarium are kept in the BAS Archives (LS2/4). The records can be searched and downloaded on: http://apex.nerc-bas.ac.uk/f?p=148:1. There is also a facility to see a distribution map of specimens retrieved by querying the database.