The dataset comprises of vertical profiles of water column properties (temperature, salinity, conductivity, pressure, depth, sound velocity and density) of the full water column in the South West region of the UK. Measurements were taken opportunistically at three main locations (L4, L5 and E1 Western Channel Observatory stations) as well from Plymouth Sound and the surrounding inshore areas. Data have been gathered using a Valeport MIDAS 606 CTD (with a passive flow induction cell, Platinum Resistance Thermometer and a strain gauge transducer) and extracted and processed using Valeport DataLogX2 software (version1.0.4.1270). The CTD was deployed using vertical deployment from the RV MBA Sepia and were hauled using a manually controlled hydraulic winch. The surveyors have been dependent on the sensor calibrations applied by the CTD manufacturer (Valeport). Manufacturer calibrations are applied to the in situ direct measurements via sensor specific microchips in the CTD unit. Derived parameters are calculated using the in-built processing provided with the units software: Datalogx2. The data have been collected in the framework of the long term monitoring of the Western Channel Observatory stations and the Plymouth inshore fisheries undertaken annually by the Marine Biological Association of the United Kingdom. The RV MBA Sepia department of the Institute carried out the data collection activities.

Results of sediment trap analysis conducted by British Antarctic Survey, University of Edinburgh and University of Bristol. Abundances and biovolume of intact phytoplankton and microzooplankton cells observed in sediment trap samples are presented. Data from two sediment traps deployed in the Scotia Sea, Southern Ocean, are presented (shallow=400 m, and deep = 2000 m). 4 samples were analysed from each, two in January/February 2018, and two in December 2018. Each sediment trap sample was split into multiple fractions to facilitate this and other analyses. Data facilitate the understanding of the magnitude and drivers of particulate fluxes in the Scotia Sea, Southern Ocean. Work funded by NC-ALI funding to the British Antarctic Survey Ecosystems programme.

Marine macronutrient and particulate material concentrations together with phytoplankton abundance and community composition were measured from samples taken during British Antarctic Survey and UK National Oceanography Centre research cruise JC211 to the Scotia Sea, Southern Ocean, carried out onboard RRS James Cook in February-March 2021. Samples were taken from four sections of the cruise: (i) at the British Antarctic Survey Scotia Sea Open-Ocean Observatory (SCOOBIES) P3 mooring in the Georgia Basin, northwest of South Georgia; (ii) as part of the British Antarctic Survey long-term Polar Ocean Ecosystem Time Series - Western Core Box (POETS-WCB) survey at South Georgia; (iii) in the vicinity of giant iceberg A-68A and associated icebergs; and (iv) as part of the A23 repeat hydrographic section. Samples were collected to maximum depth of approximately 500 m from Niskin water bottles attached to a CTD rosette. Full data analyses were performed post-cruise. Concurrent temperature, salinity, dissolved oxygen, chlorophyll fluorescence and photosynthetically active radiation (PAR) measurements obtained from analysis of water samples and from sensors on the CTD system at the depth and time of each water sample are provided for environmental context. RRS James Cook cruise JC211 was in part supported by the Natural Environment Research Council (NERC) National Capability Science (Antarctic Logistics and Infrastructure; NC-ALI) programme. Further funding for sampling around iceberg A-68 was provided by the Government of South Georgia and the South Sandwich Islands and the UK Government Blue Belt Programme. Data acquisition and analyses were supported by NERC NC-ALI funding to the Ecosystems CONSEC Programme and NERC Grants NE/N018095/1 (ORCHESTRA) and NE/V013254/1 (ENCORE) at the British Antarctic Survey, and by the European Research Council (ERC Starting Grant 678371 ICY-LAB to K Hendry) and NERC Grant NE/K010034/1 (to SF Henley).

Mesozooplankton were collected with a MOCNESS net system during the oceanographic cruise JR17005 (May and June 2018) and JR18007 (August 2019). The MOCNESS comprised 9 separate nets which opened in sequence such that the closing of one net opened the next; net 1 was open during the descent of the net to its maximum depth (about 1000 m) while the remaining 8 depths opened at regular intervals during the reascent to the surface. Catches were immediately preserved in 4 percent buffered formaldehyde after division by a Folsom splitter into either 0.5 or 0.25 fractions. Identification of taxa was performed by Continuous Plankton Recorder survey analysts at the Marine Biological Association UK, led by Marianne Wootton. Specimens were categorised to the lowest possible taxonomic level, which, in some cases, encompassed developmental stages but, in other cases, was limited to higher order taxa. Each taxa was enumerated to determine abundance with the preserved fraction of the catch. These were scaled up to the whole catch and divided by the volume filtered of the respective net to determine abundance in units of individuals m-3. These values were also multiplied by the sampled depth interval to derive the alternative unit of individuals m-2. The samples from three net deployments were analysed from both JR17005 and JR18005 in approximately matching locations between Greenland and Svalbard, encompassing the Fram Strait. The dataset allows examination of the distribution and abundance of these species across the region in two separate years, with the first year covering early summer and the second year, late summer. Financial support for was provided by Changing Arctic Ocean (CAO) Programme DIAPOD, funded by UKRI Natural Environment Research Council (NERC; NE/P006213/1, NE/P006353/1, NE/P006302/1, NE/P006183/1,and NE/P005985/1, amongst others), and by CAO Project CHASE, jointly funded by NERC (NE/R012733/1) and the German Federal Ministry of Education and Research (BMBF; 03F0803A).

The cross-disciplinary themes will result in a diverse data catalogue. The ship collected data will be in the form of sea surface meteorology (2-D wind speed and direction, total irradiance, Photosynthetically Active Radiation/PAR, air temperature, atmospheric pressure, humidity); atmospheric carbon dioxide (pCO2); biological, chemical and physical properties and processes in the marine photic zone (carbonate chemistry - pCO2, total alkalinity, pH, DIC; dissolved gases - oxygen; nutrient concentrations, ammonium regeneration, nitrification, nitrogen fixation, zooplankon ecology, chlorophyll concentration, photosynthetic pigment composition, bacterial production, phytoplankton and bacterial speciation, concentrations of biogenic trace compounds such as dimethyl sulphide/DMS and dimthylsulphoniopropionate/DMSP, salinity, temperature, zooplankon ecology) and bioassays of these same parameters under different future IPCC CO2 and temperature scenarios. The long-term (18 month) laboratory based mesocosm experiments will include data on individual organism response (growth, immune response, reproductive fitness) under different future IPCC CO2 and temperature scenarios in rocky intertidal, soft sediment and calcareous biogenic habitats, as well as the effects on commercially important species of fish and shellfish. The analysis of sediment cores will provide greater resolution of the paleo record during the Paleocene-Eocene Thermal Maximum (PETM). Data will be used to aid the parameterisation of coastal and continental shelf seas (Northern Europe and the Arctic) model runs as well as larger scale global models. The shipboard fieldwork will take place around the UK, in the Arctic Ocean and the Southern Ocean. The mesocosms will look at temperate marine species common to UK shelf seas. Sediment cores have been collected from Tanzania. The models will look from the coastal seas of Northern Europe to the whole globe. Data to be generated will include data collected at sea, short-term (2-3 day) ship-board bioassays, from long-term (18 month) laboratory based mesocosm experiments and reconstructed paleo records from sediment cores. The 5 year UK Ocean Acidification Research Programme is the UK’s response to growing concerns over ocean acidification. Aims: 1 - to reduce uncertainties in predictions of carbonate chemistry changes and their effects on marine biogeochemistry, ecosystems and other components of the Earth System; 2 - to understand the responses to ocean acidification, and other climate change related stressors, by marine organisms, biodiversity and ecosystems and to improve understanding of their resistance or susceptibility to acidification; 3 - to provide data and effective advice to policy makers and managers of marine bioresources on the potential size and timescale of risks, to allow for development of appropriate mitigation and adaptation strategies. The study unites over 100 marine scientists from 27 institutions across the UK. It is jointly funded by Department for Environment, Food and Rural Affairs (Defra), the Natural Environment Research Council (NERC) and Department of Energy and Climate Change (DECC).