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This data set contains the ice thickness data as recorded with the AWI airborne radar system (Nixdorf et al., 1999), operated with a 150 MHz pulse of 600 ns duration. Some 20000 line kilometres of ice thickness data were recorded in the Dome Fuji region, Antarctica. These data contain the corrected and ungridded product. The original gridded product is available through doi:10.1594/PANGAEA.891323 (Karlsson et al., 2018).

Cable bacteria are multicellular, filamentous microorganisms that are capable of transporting electrons over centimeter-scale distances. Although recently discovered, these bacteria appear to be widely present in the seafloor, and when active they exert a strong imprint on the local geochemistry. In particular, their electrogenic metabolism induces unusually strong pH excursions in aquatic sediments, which induces considerable mineral dissolution, and subsequent mineral reprecipitation. However, at present, it is unknown whether and how cable bacteria play an active or direct role in the mineral reprecipitation process. To this end we present an explorative study of the formation of sedimentary minerals in and near filamentous cable bacteria using a combined approach of electron microscopy and spectroscopic techniques. Our observations reveal the formation of polyphosphate granules within the cells and two different types of biomineral formation directly associated with multicellular filaments of these cable bacteria: (i) the attachment and incorporation of clay particles in a coating surrounding the bacteria and (ii) encrustation of the cell envelope by iron minerals. These findings suggest a complex interaction between cable bacteria and the surrounding sediment matrix, and a substantial imprint of the electrogenic metabolism on mineral diagenesis and sedimentary biogeochemical cycling. In particular, the encrustation process leaves many open questions for further research. For example, we hypothesize that the complete encrustation of filaments might create a diffusion barrier and negatively impact the metabolism of the cable bacteria.

We used a multibeam echosounder (Reson7125) front-mounted onto the ROV Isis (Dive D333, DY081 expedition) to map the terrain of a vertical feature marking the edge of a deep-sea glacial trough (Labrador Sea, [63°51.9'N, 53°16.9'W, depth: 650 to 800 m]). After correction of the ROV navigation (i.e. merging of USBL and DVL), bathymetry [m] and backscatter [nominal unit] were extracted at a resolution of 0.3 m and different terrain descriptors were computed: Slope, Bathymetric Position Index (BPI), Terrain Ruggedness Index, Roughness, Mean and Gaussian curvatures and orientations (Northness and Eastness), at scales of 0.9, 3 and 9 m. Using a Principal Component Analysis (PCA), the terrain descriptors enabled to retrieve 4 terrain clusters and their associated confusion index, to investigate the spatial heterogeneity of the terrain. This approach also underlined the presence of geomorphic features in the wall terrain. The extraction of the backscatter intensity for the first time considering vertical terrains, opens space for further acquisition and processing development. Using photographs collected by the ROV Isis (Dive D334, DY081 expedition), epibenthic fauna was annotated. Each image was linked to a terrain cluster in the 3D space and pooled into 20-m² bins of images. A Bray-Curtis dissimilarity matrix was constructed from morphospecies abundances. This enabled to test for differences of assemblage composition among clusters. Few species appeared more abundant in particular clusters such as L. pertusa in high-roughness cluster. However, nMDS suggested differences in assemblage composition but these dissimilarities were not strongly delineated. Whereas the design of this study may have limited distinctive differences among assemblages, this shows the potential of this cost-effective method of top-down habitat mapping to be applied in undersampled benthic habitat in order to provide a priori knwoledge for defining appropriate sampling design.

As a proxy for zooplankton and micronekton biomass in the water column, acoustic backscatter intensity (dB), acquired using a Lowered Acoustic Doppler Current Profiler (LADCP) down to ca. 4000 m depth along the Malaspina Expedition (CSD2008-00077). Datasets are from 7 different legs around the World (1-7): 1 Spain-Brazil, 2 Brazil-South Africa, 3 South Africa-West Australia, 4 West Australia-East Australia, 5 East Australia-Hawaii, 6 Hawaii-Panamá, 7 Panamá-Spain.

Gordon & Betty Moore FoundationGordon and Betty Moore Foundation [5596]; Canada Research Chairs FoundationCanada Research Chairs; European Union's Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant [747946]; Fundacao para a Ciencia e Tecnologia I.P. Portugal (FCT); Direcao-Geral de Politica do Mar (DGPM) [2/2017/001-MiningImpact 2]; FCTPortuguese Foundation for Science and TechnologyEuropean Commission [CEECIND005262017, UID/MAR/00350/2013, IF/01194/2013, IF/00029/2014/CP1230/CT0002, Mining2/0005/2017]; RF State Assignment [0149-2019-0009]; Horizon 2020 Agricultural Interoperability and Analysis System (ATLAS) projects [678760]; JM Kaplan Fund; National Science FoundationNational Science Foundation (NSF) [OCE 1634172]; JPI Oceans project Mining Impact -Environmental Impacts and Risks of Deep-Sea Mining Aug 2018-Feb 2022 (NWO-ALW) [856.18.001] info:eu-repo/semantics/publishedVersion

This data set contains hydrographic measurements of high spatial resolution which were collected during a shipboard survey onboard RV Knorr in September 2011. The survey included transects across the northern slope of Iceland and the Iceland-Faroe Ridge. The sections are named A to E starting with the north-westernmost transect. The hydrographic data were obtained using a Sea-Bird 911+ conductivity-temperature-depth (CTD) instrument. The CTD was mounted on a rosette with Niskin bottles to collect water samples, which were used to calibrate the conductivity sensor. The resulting accuracy of the CTD measurements is 0.3 db for pressure, 0.001 °C for temperature, and 0.002 for salinity.

In the southern Indian Ocean, the position of the subtropical front – the boundary between colder, fresher waters to the south and warmer, saltier waters to the north – has a strong influence on the upper ocean hydrodynamics and biogeochemistry. Here we analyse a sedimentary record from the Agulhas Plateau, located close to the modern position of the subtropical front and use alkenones and coccolith assemblages to reconstruct oceanographic conditions over the past 300,000 years. We identify a strong glacial-interglacial variability in sea surface temperature and productivity associated with subtropical front migration over the Agulhas Plateau, as well as shorter-term high frequency variability aligned with variations in high latitude insolation. Alkenone and coccolith abundances, in combination with diatom and organic carbon records indicate high glacial export productivity. We conclude that the biological pump was more efficient and strengthened during glacial periods, which could partly account for the reported reduction in atmospheric carbon dioxide concentrations.

These data consist of both underway and station echosounder observations collected during the 2020 SUMMER (Sustainable Management of Mesopelagic Resources) Mediterranean cruise (30 September 2020 to 18 October 2020) on the RV Sarmiento de Gamboa. Narrowband (18, 38, 70, 120, 200 kHz) underway acoustic data were collected continuously using hull-mounted Simrad EK80 echosounders. The recording depths for the 5 frequencies were 1000, 1000, 750, 500, and 200 m respectively. Calibrations were carried out on the 1st of October 2020 using a 33 mm tungsten sphere,and the calibration results were applied to the instruments. During the survey, a Simrad wideband autonomous receiver (WBAT) was deployed down to a depth of 500 m whilst on station. In total, 31 drops were carried out at 5 stations. Four transducers (central frequencies were 45, 120, 200, 333 kHz) were operated using the WBAT in frequency modulated (FM) mode (bandwidth ranging from 45 to 445 kHz). The WBAT calibration data were collected using a 33 mm tungsten sphere. During the deployment of the WBAT, the hull-mounted EK80 was switched to FM mode to record broadband measurements. Raw power (W), number of transducer segments and transceiver impedance (Ohm) were stored in raw proprietary Simrad format (.raw, .idx).

Momarsat 2022 cruise report: summary of dives and operations, and position of moorings and observation infrastructures and sampling locations

The Arctic Ocean region is currently undergoing dramatic changes, which will likely alter the nutrient cycles that underpin Arctic marine ecosystems. Phosphate is a key limiting nutrient for marine life but gaps in our understanding of the Arctic phosphorus (P) cycle persist. In this study, we investigate the benthic burial and recycling of phosphorus using sediments and pore waters from the Eurasian Arctic margin, including the Barents Sea slope and the Yermak Plateau. Our results highlight that P is generally lost from sediments with depth during organic matter respiration. On the Yermak Plateau, remobilization of P results in a diffusive flux of P to the seafloor of between 96 and 261 μmol m−2 yr−1. On the Barents Sea slope, diffusive fluxes of P are much larger (1736–2449 μmol m−2 yr−1), but these fluxes are into near-surface sediments rather than to the bottom waters. The difference in cycling on the Barents Sea slope is controlled by higher fluxes of fresh organic matter and active iron cycling. As changes in primary productivity, ocean circulation and glacial melt continue, benthic P cycling is likely to be altered with implications for P imported into the Arctic Ocean Basin.