Description: In temperate, subpolar and polar marine systems, the classical perception is that diatoms initiate the spring bloom and thereby mark the beginning of the productive season. Contrary to this view, here we document an pre-bloom of pico- and nanophytoplankton prior to the diatom bloom; a period with excess nutrients and deep convection of the water column. During repeated visits to stations in the deep Icelandic and the Norwegian Basins and the shallow Shetland Shelf (26 March to 29 April 2012), we investigated the succession and dynamics of 〈10 µm phytoplankton. Water samples were collected from CTD rosette 10 L Niskin bottles and fixed in glutaraldehyde (final conc. 5%), flash frozen in liquid Nitrogen and stored at -80°C until analysis.

Description: In temperate, subpolar and polar marine systems, the classical perception that bacteria are carbon limited by end of winter and respond in activity and abundance to the production of new carbon during the diatom spring bloom and post bloom. Contrary to this view, we here document an strong increase in bacterial abundance and activity (latter measured by increasing high nuclei acid (HNA) to low nuclei acid (LNA) bacteria ratio) during the winter-spring transition, where phytoplankton smaller than 10 µm dominate. Further DNA-virus were enumerated and revealed the virus to bacteria ratio (VBR) to be decreasing during winter-spring transition, indicating that the virus did not increase in number accordingly to bacteria. During repeated visits to stations in the deep Icelandic and the Norwegian Basins and the shallow Shetland Shelf (26 March to 29 April 2012), we investigated the abundance of bacteria and the succession of HNA:LNA bacteria and VBR. Water samples were collected from CTD rosette .10 L Niskin bottles and fixed in glutaraldehyde (final conc. 5%), flash frozen in liquid Nitrogen and stored at -80°C until analysis.

Description: The Deep Convection cruise repeatedly sampled two locations in the North Atlantic, sited in the Iceland and Norwegian Basins, onboard the RV Meteor (19 March - 2 May 2012). Samples were collected from multiple casts of a conductivity-temperature-depth (CTD) - Niskin rosette at each station. Water samples for primary production rates, community structure, chlorophyll a [Chl a], calcite [PIC], particulate organic carbon [POC] and biogenic silicic acid [BSi] were collected from predawn casts from six light depths (55%, 20%, 14%, 7%, 5% and 1% of incident PAR). Additional samples for community structure and ancillary parameters were collected from a second cast. Carbon fixation rates were determined using the 13C stable isotope method. Water samples for diatom and micro zooplankton counts, collected from the predawn casts, were preserved with acidic Lugol's solution (2% final solution) and counted using an inverted light microscope. Water samples for coccolithophore counts were collected onto cellulose nitrate filters and counted using polarising light microscopy. Water samples for Chl a analysis were filtered onto MF300 and polycarbonate filters and extracted in 90% acetone. PIC and BSi samples were filtered onto polycarbonate filters and analysed using an inductively coupled plasma emission optical spectrometer and a SEAL QuAAtro autoanalyser respectively.

Description: Data were collected on and off the shelf northwest of Svalbard during cruises in January, March, May, August and November 2014. The sampling depths were 1, 5, 10, 20, 30, 50, 100, 200, 500, 750, and 1000 m, as well as at the depth of the Chl a maximum. The sampling concentrated on the core of the northwards drifting warm Atlantic water, which enters the Arctic Ocean north of Svalbard either south or north of the Yermark plateau. Transects were sampled across the core of the Atlantic water inflow at 79N, and additionally at 79.4N in May and August. Heavy drift ice restricted the sampling to the shelf and shelf-break in May and August 2014. During January, March, and November, the area north of Svalbard was largely ice-free, which allowed sampling off the shelf-break into the Arctic Ocean during winter. At all stations, depth profiles of temperature, salinity and fluorescence were taken with a CTD (Seabird SBE 911 plus). Water was sampled with Niskin bottles from discrete depths for analysis of inorganic nutrients, chlorophyll a (Chl a), microbial abundance, bacterial production (BP), as well as DOM and POM. In May and August, three process stations each (in datasheet referred to as P-stations: P1, P3, P4 in May, and P5, P6, P7 in August, at these stations more time-demanding processes were investigated, such as in situ primary production and vertical export of POM. Chl a was determined by filterig 100-500mL water onto Whatmann GF/F glass fiber filters. Chl a was determined fluorometrically (10-AU, Turner Designs) from triplicates of each filter type after extraction in 5 mL methanol at room temperature in the dark for 12 h without grinding. Abundances of microorganisms: picophytoplankton, nanophytoplankton, virus, heterotrophic bacteria, and heterotrophic nanoflagellates were determined on an Attune(R) Focusing Flow Cytometer (Applied Biosystems by Life technologies) with a syringe-based fluidic system and a 20 mW 488 nm (blue) laser. Samples were fixed with glutaraldehyde (0.5% final conc.) at 4°C for minimum 2 h, shock frozen in liquid nitrogen, and stored at -80 °C until analysis. Total organic carbon (TOC) in unfiltered seawater was analyzed by high temperature combustion using a Shimadzu TOC-VCSH. All samples were acidified with HCl (to a pH of around 2) and bubbled with pure N2 gas in order to remove any inorganic carbon. Calibration was performed using deep seawater and low carbon reference waters. A blank consisting of milliQ water was analyzed every eighth sample to assess the day-to-day instrument variability. Concentration of total nitrogen (TN) was determined simultaneously by high temperature combustion using a CPH-TN nitrogen analyzer. Total organic nitrogen (TON) was calculated by subtracting the inorganic nitrogen (NOx = NO3 + NO2 + NH4+) measured from parallel nutrient samples. The instrument was calibrated using a standard series of acetoanilide and the accuracy of the instrument was evaluated using seawater reference material provided by the Hansell CRM (consensus reference material) program. For analysis of particulate organic carbon (POC) and particulate organic nitrogen (PON), triplicate subsamples (100 - 500 mL) were filtered onto precombusted Whatman GF/F glass-fibre filters (450°C for 5 h), dried at 60°C for 24 h and analyzed on-shore with a Leeman Lab CEC 440 CHN analyzer. Prior to analysis, the dried samples were fumed by concentrated HCl in 24 h before re-drying at 60°C for 24 h to remove inorganic carbon. Unfiltered seawater was filled directly from the Niskin bottles into 30 mL acid washed HDPE bottles and stored at -20°C. Nitrite and nitrate (NO-2 + NO- 3 ), phosphate (PO3- 4 ) and silicic acid (H4SiO4) were measured on a Smartchem200 (by AMS Alliance) autoanalyser following procedures as outlined in Wood et al. (1967) for NO-3 + NO-2 , Murphy and Riley (1962) for PO3-4 and Koroleff (1983) for the determination of H4SiO4. The determination of NO-3 was done by reduction to NO-2 on a built-in cadmium column, which was loaded prior to every sample run. Seven-point standard curves were made prior to every run. Two internal standards and one blank were inserted for every 8 samples and these were used to correct for any drift in the measurements. Concentration of NH+4 was determined directly in fresh samples using ortho-phthaladehyde according to Holmes et al. (1999)

Description: As marine-ice around Antarctica retracts, a vast ‘blue carbon’ sink, in the form of living biomass, is emerging. Properly protected and promoted Antarctic blue carbon will form the world’s largest natural negative feedback on climate change. However, fulfilling this promise may be challenging, given the uniqueness of the region and the legal systems that govern it. In this interdisciplinary study, we explain: the global significance of Antarctic blue carbon to international carbon mitigation efforts; the urgent need for international legal protections for areas where it is emerging; and the hurdles that need to be overcome to realize those goals. In order to progress conservation efforts past political blockages we recommend the development of an inter-instrument governance framework that quantifies the sequestration value of Antarctic blue carbon for attribution to states’ climate mitigation commitments under the 2015 Paris Agreement. Key policy insights Blue-carbon emergence around Antarctica’s coastlines will potentially store up to 160,000,000 tonnes of carbon annually. Blue-carbon will emerge in areas of rich biomass that will make it vulnerable to harvesting and other human activities; it is essential to incentivise conserving, rather than commercial exploitation of newly ice-free areas of the Southern Ocean. Antarctic blue carbon is a practical and prime candidate to build a cooperative, inter-instrument, non-market mitigation around; this should be considered at the ‘blue COP’ UN Climate change discussions in Spain. Allowing Antarctic fishing states to account for the carbon storage value of blue carbon zones through a non-market approach under the Paris Agreement could provide a vital incentive to their protection under the Antarctic Treaty System. The Scientific Committee on Antarctic Research would be the ideal body to facilitate the necessary connections between the relevant climate and Antarctic governance regimes.