• European Marine Science
• 2022-2022close
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Abstract Although the rapid spread of antimicrobial resistance (AMR), particularly in relation to clinical settings, is causing concern in many regions of the globe, remote, extreme environments, such as Antarctica, are thought to be relatively free from the negative impact of human activities. In fact, Antarctica is often perceived as the last pristine continent on Earth. Such remote regions, which are assumed to have very low levels of AMR due to limited human activity, represent potential model environments to understand the mechanisms and interactions underpinning the early stages of evolution, de novo development, acquisition and transmission of AMR. Antarctica, with its defined zones of human colonisation (centred around scientific research stations) and large populations of migratory birds and animals, also has great potential with regard to mapping and understanding the spread of early-stage zoonotic interactions. However, to date, studies of AMR in Antarctica are limited. Here, we survey the current literature focussing on the following: i) Dissection of human-introduced AMR versus naturally occurring AMR, based on the premise that multiple drug resistance and resistance to synthetic antibiotics not yet found in nature are the results of human contamination ii) The potential role of endemic wildlife in AMR spread There is clear evidence for greater concentrations of AMR around research stations, and although data show reverse zoonosis of the characteristic human gut bacteria to endemic wildlife, AMR within birds and seals appears to be very low, albeit on limited samplings. Furthermore, areas where there is little, to no, human activity still appear to be free from anthropogenically introduced AMR. However, a comprehensive assessment of AMR levels in Antarctica is virtually impossible on current data due to the wide variation in reporting standards and methodologies used and poor geographical coverage. Thus, future studies should engage directly with policymakers to promote the implementation of continent-wide AMR reporting standards. The development of such standards alongside a centralised reporting system would provide baseline data to feedback directly into wastewater treatment policies for the Antarctic Treaty Area to help preserve this relatively pristine environment. Video Abstract

Fluorometric data on chlorophyll a concentration, Fluorescent Dissolved Organic Matter (FDOM) concentration, and optical backscatter were measured by a triplet fluorometer (ECO-Puck BBFL2SSC, Wetlabs) attached to a remotely operated vehicle (ROV) during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition between November 2019 and September 2020. Data use manufacturer calibration.

Mesopelagic organisms play a critical role in marine ecosystems, channelling energy and organic matter across food webs and serving as the primary prey for many open-ocean predators. Nevertheless, trophic pathways involving mesopelagic organisms are poorly understood and their contribution to food web structure remains difficult to assess (St. John et al., 2016). Existing data to assess mesopelagic feeding interactions and energy transfer are scattered in the literature or remain unpublished, making it difficult to locate and use such datasets. As part of the EU funded project SUMMER - Sustainable Management of Mesopelagic Resources H2020-BG-2018-2, GA: 817806) (https://summerh2020.eu/), we created MesopTroph, a georeferenced database of diet, trophic biogeochemical markers, and energy content of mesopelagic organisms and other marine taxa from the Northeast Atlantic and Mediterranean Sea, compiled from 191 published and non-published sources. MesopTroph includes seven datasets: (i) diet compositions from stomach content analysis, (ii) stable isotopes of carbon and nitrogen (δ13C and δ15N), (iii) fatty acid trophic markers (FATM), (iv) major and trace elements, (v) energy density, (vi) estimates of diet proportions, and (vii) trophic positions. The database contains information from 4918 samples, representing 51119 specimens from 499 species or genera, covering a wide range of trophic guilds and taxonomic groups. Metadata provided for each record include the location, dates and method of sample collection, taxonomic ranks (phylum, class, order, family), number and size (or size range) of sampled organisms, method/model used in data analysis, reference and DOI of the original data source. Compiled data were checked for errors, missing information, and to avoid duplicate entries, and scientific names and taxonomy were standardized.

Short sediment cores were taken at six stations in Wismar Bay, southern Baltic Sea (Germany) in May 2019 using a Rumohr-Lot device. Our aim in this study was to investigate the role of diagenetic element fluxes and different fresh water sources, including submarine groundwater discharge, on the water column in the bay. Porewaters were extracted from the sediment cores by applying the rhizon technique at a resolution between 2 and 5 cm. The porewaters were analyzed for major and trace metals and selected nutrients using a ICP-OES (iCAP, 7400, Duo Thermo Fischer Scientific), total sulphide by a Specord 40 spectrophotometer (Analytik Jena), dissolved inorganic carbon (DIC) and δ13CDIC using an isotope gas mass spectrometre (MAT 253) coupled to a Gasbench II, and δ18OH2O, and δ2HH2O using a CRDS system (laser cavity-ring-down-spectroscopy, Picarro L2140- I). Sediment cores were further sliced at 2 to 4 cm resolution and each freeze-dried solid subsample was analyzed for contents of total carbon, nitrogen, and sulphur using an Elemental Analyzer (Euro Vector EuroEA 3, 052), inorganic carbon using an Elemental Analyzer multi EA (Analytik Jena), total mercury by a DMA-80 analyzer, and HCl-extractable Pb, Mn and Fe using an ICP-OES (iCAP, 7400, Duo Thermo Fischer Scientific).

The data originates from the gravity core MSM12/2-5-1 (57.538500, -48.738700, recovery 1494 cm, 3492 m water depth) taken during R/V Maria S. Merian cruise MSM12/2 in 2009 in the eastern Labrador Sea (Eirik Drift). The data should provide more precise information on the timing and duration of freshwater forcing, which may help to improve simulations for past and future changes in ocean circulation and climate. We have investigated the very well-dated and high-resolution sediment core from the Eirik Drift, representing an interval from the last deglaciation to Holocene, i.e., the last 19 ka. Four meltwater-related cold events have been identified by abrupt changes in sea surface characteristics, which are based on independent multiple biomarker proxies, including sea-ice proxy IP25 and phytoplankton biomarker IP25 index (PIP25) for sea ice cover, the alkenone unsaturation index for sea surface temperature (SST), and the percentage of tetra-unsaturated alkenones (%C37:4) for meltwater inflow, and X-ray fluorescence (XRF) scanning data. Furthermore, sortable silt mean size has been used to reflect changes in bottom current intensity. In conclusion, our study could improve our understanding of the impact of meltwater injection into subpolar regions on abrupt climate changes during the last glacial termination. Furthermore, the data support modelling results that higher frequency and amplitude of abrupt changes may occur during the transition states from background climates. We found that meltwater pulses following collapse of the Laurentide Ice Sheet and/or Greenland Ice Sheet might have triggered millennial-scale abrupt changes in surface freshening and sea ice concentrations in the Labrador Sea, as well as cooling atmospheric temperatures.

Marine sediment core GL-1248 was collected from the continental slope off northern northeastern Brazil by Petrobras oil company. Sediment samples (154 in total) were collected with 2 cm wide scoops at every 10 cm from the uppermost 16 m (covering the the last 113 thousand years) of the marine sediment core GL-1248. Samples were oven‐dried at 60°C, precisely weighted to 0.5 g and treated with H2O2 27% and HCl 10% to remove organic matter and calcium carbonate, respectively. The remaining content was diluted in alcohol and three aliquots per sample were mounted on stainless steel discs with four drops of the homogenized solution of alcohol and silt/clay sediments. GL-1248 luminescence measurements were performed on an automated Lexsyg Smart TL/OSL reader equipped with blue and infrared LEDs, Hoya U-340 filters for light detection in the ultraviolet band (270-390 nm) using a photomultiplier and beta radiation sources (90Sr/90Y) with doses rate of 0.116 Gy s-1 at the Luminescence and Gamma Spectrometry Laboratory of the Institute of Geosciences, University of São Paulo, Brazil. The sensitivity representative of the 110°C thermoluminesce (TL) peak of quartz considered the 80–120°C integration range from the TL curve. The 80-120°C TL sensitivity was calculated as a percentage of the total TL emission (0-250°C) and using the background TL curve. The mean of three measured aliquots represents the TL sensitivity of each sample. The OSL sensitivity was calculated by integrating the first second of light emission and the last ten seconds as background. GL-1248 TL sensitivity data were compared to previously published data obtained from marine sediment core GeoB16206-1 (https://doi.org/10.1594/PANGAEA.904357). Marine sediment core GeoB16206-1 was analyzed in a different luminescence reader (i.e. RisØ OSL/TL DA-20 reader) and using different regeneration dose. In order to avoid machine artifacts and the influence of dose size on sensitivity, we normalized the TL data output from both marine sediment cores and produced a composite record. Name of the Campaign: collected by the Petrobras oil company Event Label: GL1248 (GL-1248) Method: quarzt luminescence sensitivity Latitude: -0.920000 Longitude: -43.401667 Elevation: -2,264 m

Here, we present a comprehensive, seasonal observation of chromophoric dissolved organic matter (CDOM) as well as dissolved organic carbon (DOC) in the Central Arctic Ocean (CAO) including ocean water column samples and Lead water samples based on the year round (November 2019 - September 2020) expedition “Multidisciplinary Drifting Observatory for the Study of Arctic Climate” (MOSAiC). Ocean water samples taken from the CTD/rosette on Polarstern or the one based on the ice floe ('Ocean City', Rabe et al., 2022) were filtered through pre-combusted (450 °C, 5 h) glass fiber filters (Whatman; GF/F), subsequently for DOC and total dissolved nitrogen (TDN), as well as absorbance and fluorescence excitation-emission matrices (EEMs) measurements. Lead water samples were collected using the peristatic pump (Master flex E/S portable sampler) between August 25th and September 4th 2020 in summer in the Amundsen Basin, then filtered through an in line 0.2 µm pore size Sterivex cartridge filter (polyethersulfone membrane) and subsequently for DOC and TDN, as well as absorbance and EEMs measurements. Salinity for Lead water samples was measured with a hand-held multi parameter meter (Cond 340i, WTW). DOC and TDN were determined by high temperature catalytic oxidation (HTCO) and non dispersive infrared spectroscopy and chemiluminescence detection (TOC VCPN, Shimadzu; for details see Ksionzek et al., 2018). EEMs were measured using a spectrofluorometer (Aqualog, Horiba) equipped with a charge-coupled device (CCD) detector. CDOM absorbance spectra were acquired by a spectrophotometer (UV2700, Shimadzu) in a quartz cuvette with an optical path length of 10. To inventive the influence of the transpolar drift (TPD) on the MOSAiC expedition, we compared the MOSAiC ocean water columns with the ocean water columns in the western Nansen Basin and Yermak Plateau from the Norwegian young sea ICE (N ICE2015) expedition (January to June 2015; Granskog et al., 2018), and the ocean water columns in the Bering Strait, Laptev Sea, and East Siberian Sea that were acquired during the expedition TA19_4 (September to October 2019, Hölemann et al., 2021). The EEMs combined with parallel factor analysis (PARAFAC) model based on MOSAiC, N ICE2015 and TA19_4 expeditions were processed by the staRdom package in R studio (Version 3.5.1; Pucher et al., 2019). Five PARAFAC components were determined, subsequently we named as C475, C440, C395, C340, and C320 according to their fluorescence emission maxima.

Individual species were identified and 550 individuals per species were picked from the >250 µm fraction under dissecting microscope for each sample. Approximately 7 mg of picked and identified foraminifera shells were crushed between glass microscope slides and rinsed with MilliQ water. Samples were cleaned prior to δ¹⁵NFB measurement as described in Marcks et al., (2023). Once samples were clean, organic nitrogen was released into solution by acid dissolution of the foraminiferal calcite. Samples were acidified prior to measurement. Nitrate concentrations were measured by chemiluminescence on a Teledyne Instruments (Model 200E) chemiluminescence NO/NOx analyzer. δ15NFB samples, 10 nmol in size, were measured by bacterial conversion of nitrate to nitrous oxide, with measurement of the δ¹⁵N of the nitrous oxide by automated extraction and gas chromatography-isotope ratio mass spectrometry on a Thermo Delta V Plus IRMS. The potassium nitrate reference materials IAEA-N3 and USGS 34 (+4.7 ‰ and 1.8 ‰, respectively) were used to standardize results (Gonfiantini et al., 1995). Note, testing of a subset of 6 samples, each with full procedural triplicates, for a total of 18 samples, showed negligible differences in nitrogen content and δ¹⁵NFB values with and without a reductive cleaning step, and so it was omitted here to avoid unnecessary loss of sample material. Sample replicates and triplicates were analyzed when possible. Full procedural replicates were analyzed for 134 sample splits, representing 66 unique samples, when enough foraminifera were available for duplicate or triplicate analysis. The average standard deviation of procedural replicates is 0.4 ‰. Full operational blanks and amino acid standards (USGS 65 glycine) were measured in each batch. The average standard deviation of glycine standards measured in triplicate is 0.3 ‰. We estimated the δ¹⁵N value of the persulfate blank using a dilution series (5, 7.5, 10, and 20 μM of the glycine standard and the fraction of the blank in standards. We applied a blank correction to each sample based on the calculated mean δ¹⁵N value of all of the persulfate blanks for the dataset and the fraction of the blank in the N content of each sample. Data were subset to exclude N content outliers (>2 s.d. from mean and where the blank was greater than 20 % of the sample N content, with significantly different δ¹⁵N values from other replicates). Full propagated analytical error associated with measurement and blank correction, following Higgins et al., (2009, doi:10.1021/ac8017185 ), was on average 0.6 ‰. Propagating the errors, including not only the procedural replicates and their variance, but the relative size of the blanks, the mean of the calculated blank δ¹⁵N values (5± 10 ‰). The mean value, 0.6 ‰, is used where procedural replicates were limited by sample availability. The age model is based on the benthic oxygen isotope stratigraphy presented by Starr et al. (2021, doi:10.1038/s41586-020-03094-7). This age model for Site 361-U1475 was generated with 12 radiocarbon dates and 33 benthic oxygen isotope tie points which were graphically aligned with a probabilistic stack of 180 globally distributed benthic oxygen isotope records (Starr et al., 2021, doi:10.1038/s41586-020-03094-7).