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The size of the last glacial ice sheet on the Northeast (NE) Greenland shelf and its interaction with ocean circulation have been the subject of debate. Here we provide insights into the extent of the ice sheet around the Last Glacial Maximum (LGM) and investigate timing and strength of changes in the flow of Atlantic Water. The study is based on a multiproxy investigation of a marine sediment core, gravity core DA17-NG-ST01-019G, from 323-m water depth at the NE Greenland shelf edge at 79.4°N. We present benthic and planktic foraminiferal distribution data, AMS-14C dates, sedimentological (ice-rafted debris (IRD) and grain sizes), and geochemical (XRF) data in combination with geophysical (sub-bottom profiler) data. The oldest sediments at the study site are dated to 25.5–17.5 ka, encompassing the time frame from the beginning of the LGM to the early deglaciation. This part is overlain by sediments from the late deglaciation and Holocene. The deposits dating from the LGM are very rich in both planktic and benthic foraminifera and macrofossils of excellent preservation. The faunas show that the site generally was affected by a strong flow of relatively warm subsurface Atlantic Water during the LGM and Early Holocene. Conditions turned more polar with cold bottom water flow in the Middle–Late Holocene (c. 7.5 ka to Recent) with presence of mainly agglutinated benthic foraminiferal species. Our data from the LGM also indicate that the deposits were mixed by iceberg scouring, confirmed by the geophysical data showing extensive ploughing of the sediments on the outer shelf area. The results further indicate that the Greenland Ice Sheet did not reach to the edge of the NE Greenland shelf at 79.4°N during the LGM 24–18 ka.

The radiogenic isotope compositions of strontium (Sr) and neodymium (Nd) on the surface of the Earth are powerful tools for tracing dust sources and sinks on the Earth's surface. To differentiate between the spatial variabilities in eolian dust sources in key cryospheric regions at the three poles (the Arctic; Antarctica; and the “third pole”, covering the high mountainous area in Asia), a dataset of Sr–Nd isotopic compositions from extremely cold or arid terrestrial environments was compiled, similar to the method of Blanchet (2019). The database includes Holocene and Quaternary snow, ice, sand, soil (loess), sediment, and rock samples from the three poles based on 90 different references and our own measurement data, with a total of 1989 data points, comprising 206 data points with different grain sizes and 212 data points with fraction measurements. There are 485 data points from the third pole, 727 data points from the Arctic, and 777 data points from Antarctica. The sampling and measurement methods of these data are introduced. For each pole, geographical coordinates and other information are provided. The main scientific purpose of this dataset is to provide a Sr–Nd dataset based on collective documentation and our own measurements, which will be useful for determining the sources and transport pathways of dust in snow, ice, rivers, and oceans at or near the three poles as well as to investigate whether multiple dust sources are present at each of the poles. This dataset provides exhaustive detailed documentation of the isotopic signatures at the three poles during specific time intervals in the Quaternary period, which are useful for understanding the sources or sinks of eolian dust and sediments at the three poles. The dataset is available from the National Tibetan Plateau Data Center (https://doi.org/10.11888/Cryos.tpdc.272100, Du, 2022).

Two lander-based devices, the Bubble-Box and GasQuant-II, were used to investigate the spatial and temporal variability and total gas flow rates of a seep area offshore Oregon, United States. The Bubble-Box is a stereo camera–equipped lander that records bubbles inside a rising corridor with 80 Hz, allowing for automated image analyses of bubble size distributions and rising speeds. GasQuant is a hydroacoustic lander using a horizontally oriented multibeam swath to record the backscatter intensity of bubble streams passing the swath plain. The experimental set up at the Astoria Canyon site at a water depth of about 500 m aimed at calibrating the hydroacoustic GasQuant data with the visual Bubble-Box data for a spatial and temporal flow rate quantification of the site. For about 90 h in total, both systems were deployed simultaneously and pressure and temperature data were recorded using a CTD as well. Detailed image analyses show a Gaussian-like bubble size distribution of bubbles with a radius of 0.6–6 mm (mean 2.5 mm, std. dev. 0.25 mm); this is very similar to other measurements reported in the literature. Rising speeds ranged from 15 to 37 cm/s between 1- and 5-mm bubble sizes and are thus, in parts, slightly faster than reported elsewhere. Bubble sizes and calculated flow rates are rather constant over time at the two monitored bubble streams. Flow rates of these individual bubble streams are in the range of 544–1,278 mm3/s. One Bubble-Box data set was used to calibrate the acoustic backscatter response of the GasQuant data, enabling us to calculate a flow rate of the ensonified seep area (∼1,700 m2) that ranged from 4.98 to 8.33 L/min (5.38 × 106 to 9.01 × 106 CH4 mol/year). Such flow rates are common for seep areas of similar size, and as such, this location is classified as a normally active seep area. For deriving these acoustically based flow rates, the detailed data pre-processing considered echogram gridding methods of the swath data and bubble responses at the respective water depth. The described method uses the inverse gas flow quantification approach and gives an in-depth example of the benefits of using acoustic and optical methods in tandem.

An ice core drilled on the Renland ice cap in east-central Greenland contains a continuous climate record dating through the last glacial period. The Renland record is valuable because the coastal environment is more likely to reflect regional sea surface conditions compared to inland Greenland ice cores that capture synoptic variability. Here we present the δ18O water isotope record for the Holocene, in which decadal-scale climate information is retained for the last 8 kyr, while the annual water isotope signal is preserved throughout the last 2.6 kyr. To investigate regional climate information preserved in the water isotope record, we apply spectral analysis techniques to a 300-year moving window to determine the mean strength of varying frequency bands through time. We find that the strength of 15–20-year δ18O variability exhibits a millennial-scale signal in line with the well-known Bond events. Comparison to other North Atlantic proxy records suggests that the 15–20-year variability may reflect fluctuating sea surface conditions throughout the Holocene, driven by changes in the strength of the Atlantic Meridional Overturning Circulation. Additional analysis of the seasonal signal over the last 2.6 kyr reveals that the winter δ18O signal has experienced a decreasing trend, while the summer signal has predominantly remained stable. The winter trend may correspond to an increase in Arctic sea ice cover, which is driven by a decrease in total annual insolation, and is also likely influenced by regional climate variables such as atmospheric and oceanic circulation. In the context of anthropogenic climate change, the winter trend may have important implications for feedback processes as sea ice retreats in the Arctic.

17 pags., 4 figs., 2 tabs., Sea ice plays a pivotal role in Earth's climate and its past reconstruction is crucial to investigate the connections and feedbacks with the other components of the climate system. Among the available archives that store information of past sea ice are marine and ice cores. Recent studies on the IP biomarker extracted from marine sediments has shown great skill to infer past changes of Arctic sea ice. In ice matrixes, sodium, bromine and iodine have shown potential to store the fingerprint of sea ice presence. The development of an unambiguous sea ice proxy from ice cores, however, has proven to be a challenging task especially in the Arctic realm. In this work we analyze the sodium, bromine and iodine records in the RECAP ice core, coastal eastern Greenland, to investigate the sea ice variability in the northern North Atlantic Ocean through the last 11,000 years of the current interglacial, i.e. the Holocene. We compare the RECAP records with marine sea ice proxy records available from the northern North Atlantic. We suggest that RECAP sodium concentrations can be associated with variability of sea ice extent, while the bromine-to-sodium ratios and iodine are associated respectively with seasonal sea ice and bioproductivity from open ocean and fresh sea ice surfaces. According to our interpretation, we find that sea ice was at its lowest extent and seasonal in nature during the early Holocene in all regions of the North Atlantic. Increasing sea ice signals are seen from ca. 8–9 ka b2k, in line with long-term Holocene cooling. The increasing sea ice trend appears uninterrupted in the Fram Strait and North Iceland while reaching a maximum ca. 5 ka b2k in the East Greenland region. Sea ice modifications during the last 5000 years display great variability in East Greenland with intermediate conditions between the early and mid Holocene, possibly associated with local fjord dynamics. The last sea ice maximum was reached across all regions 1000 years b2k., The RECAP ice coring effort was financed by the Danish Research Council through a Sapere Aude grant, the NSF through the Division of Polar Programs, the Alfred Wegener Institute, and the European Research Council under the European Community's Seventh Framework Programme (FP7/2007e2013)/ERC grant agreement The RECAP ice coring effort was financed by the Danish Research Council through a Sapere Aude grant, the NSF through the Division of Polar Programs, the Alfred Wegener Institute, and the European Research Council under the European Community's Seventh Framework Programme (FP7/2007e2013)/ERC grant agreement 610055 through the Ice2Ice project. Additional funding support for the paper has been provided by the Centre for Climate Dynamics at the Bjerknes Centre. through the Ice2Ice project. Additional funding support for the paper has been provided by the Centre for Climate Dynamics at the Bjerknes Centre.

Sea spray aerosols (SSAs) have profound effects on our climate and ecosystems. They also contain microbiota and biogenic molecules which could affect human health. Yet the exposure and effects of SSAs on human health remain poorly studied. Here, we exposed human lung cancer cells to extracts of a natural sea spray aerosol collected at the seashore in Belgium, a laboratory-generated SSA, the marine algal toxin homoyessotoxin and a chemical inhibitor of the mammalian target of rapamycin (mTOR) pathway. We observed significant increased expression of genes related to the mTOR pathway and Proprotein convertase subtilisin/kexin type 9 (PCSK9) after exposure to homoyessotoxin and the laboratory-generated SSA. In contrast, we observed a significant decrease in gene expression in the mTOR pathway and of PCSK9 after exposure to the natural SSA and the mTOR inhibitor, suggesting induction of apoptosis. Our results indicate that marine biogenics in SSAs interact with PCSK9 and the mTOR pathway and can be used in new potential pharmaceutical applications. Overall, our results provide a substantial molecular evidence base for potential beneficial health effects at environmentally relevant concentrations of natural SSAs.

The Greenland Ice Sheet is currently not accounted for in Arctic mercury budgets, despite large and increasing annual runoff to the ocean and the socio-economic concerns of high mercury levels in Arctic organisms. Here we present concentrations of mercury in meltwaters from three glacial catchments on the southwestern margin of the Greenland Ice Sheet and evaluate the export of mercury to downstream fjords based on samples collected during summer ablation seasons. We show that concentrations of dissolved mercury are among the highest recorded in natural waters and mercury yields from these glacial catchments (521–3,300 mmol km−2 year−1) are two orders of magnitude higher than from Arctic rivers (4–20 mmol km−2 year−1). Fluxes of dissolved mercury from the southwestern region of Greenland are estimated to be globally significant (15.4–212 kmol year−1), accounting for about 10% of the estimated global riverine flux, and include export of bioaccumulating methylmercury (0.31–1.97 kmol year−1). High dissolved mercury concentrations (~20 pM inorganic mercury and ~2 pM methylmercury) were found to persist across salinity gradients of fjords. Mean particulate mercury concentrations were among the highest recorded in the literature (~51,000 pM), and dissolved mercury concentrations in runoff exceed reported surface snow and ice values. These results suggest a geological source of mercury at the ice sheet bed. The high concentrations of mercury and its large export to the downstream fjords have important implications for Arctic ecosystems, highlighting an urgent need to better understand mercury dynamics in ice sheet runoff under global warming. Meltwaters from the southwestern margin of the Greenland Ice Sheet contain exceptionally high concentrations of mercury, exporting up to more than 200 kmol of dissolved mercury every year, suggest mercury measurements from three glacial catchments.

Understanding ice sheet behaviour in the geological past is essential for evaluating the role of the cryosphere in the climate system and for projecting rates and magnitudes of sea level rise in future warming scenarios1–4. Although both geological data5–7 and ice sheet models3,8 indicate that marine-based sectors of the East Antarctic Ice Sheet were unstable during Pliocene warm intervals, the ice sheet dynamics during late Pleistocene interglacial intervals are highly uncertain3,9,10. Here we provide evidence from marine sedimentological and geochemical records for ice margin retreat or thinning in the vicinity of the Wilkes Subglacial Basin of East Antarctica during warm late Pleistocene interglacial intervals. The most extreme changes in sediment provenance, recording changes in the locus of glacial erosion, occurred during marine isotope stages 5, 9, and 11, when Antarctic air temperatures11 were at least two degrees Celsius warmer than pre-industrial temperatures for 2,500 years or more. Hence, our study indicates a close link between extended Antarctic warmth and ice loss from the Wilkes Subglacial Basin, providing ice-proximal data to support a contribution to sea level from a reduced East Antarctic Ice Sheet during warm interglacial intervals. While the behaviour of other regions of the East Antarctic Ice Sheet remains to be assessed, it appears that modest future warming may be sufficient to cause ice loss from the Wilkes Subglacial Basin. Studies of an Antarctic marine sediment core suggest that the East Antarctic Ice Sheet retreated in the vicinity of the Wilkes Subglacial Basin during extended warm periods of the late Pleistocene, when temperatures were similar to those predicted to occur within this century.

The onset of the North Atlantic Deep Water formation is thought to have coincided with Antarctic ice-sheet growth about 34 million years ago (Ma). However, this timing is debated, in part due to questions over the geochemical signature of the ancient Northern Component Water (NCW) formed in the deep North Atlantic. Here we present detailed geochemical records from North Atlantic sediment cores located close to sites of deep-water formation. We find that prior to 36 Ma, the northwestern Atlantic was stratified, with nutrient-rich, low-salinity bottom waters. This restricted basin transitioned into a conduit for NCW that began flowing southwards approximately one million years before the initial Antarctic glaciation. The probable trigger was tectonic adjustments in subarctic seas that enabled an increased exchange across the Greenland–Scotland Ridge. The increasing surface salinity and density strengthened the production of NCW. The late Eocene deep-water mass differed in its carbon isotopic signature from modern values as a result of the leakage of fossil carbon from the Arctic Ocean. Export of this nutrient-laden water provided a transient pulse of CO2 to the Earth system, which perhaps caused short-term warming, whereas the long-term effect of enhanced NCW formation was a greater northward heat transport that cooled Antarctica.

To determine community composition and physiological status of early spring sea-ice organisms, we collected sea-ice, slush and under-ice water samples from the Baltic Sea. We combined light microscopy, HPLC pigment analysis and pyrosequencing, and related the biomass and physiological status of sea-ice algae with the protistan community composition in a new way in the area. In terms of biomass, centric diatoms including a distinct Melosira arctica bloom in the upper intermediate section of the fast ice, dinoflagellates, euglenoids and the cyanobacterium Aphanizomenon sp. predominated in the sea-ice sections and unidentified flagellates in the slush. Based on pigment analyses, the ice-algal communities showed no adjusted photosynthetic pigment pools throughout the sea ice, and the bottom-ice communities were not shade-adapted. The sea ice included more characteristic phototrophic taxa (49%) than did slush (18%) and under-ice water (37%). Cercozoans and ciliates were the richest taxon groups, and the differences among the communities arose mainly from the various phagotrophic protistan taxa inhabiting the communities. The presence of pheophytin a coincided with an elevated ciliate biomass and read abundance in the drift ice and with a high Eurytemora affinis read abundance in the pack ice, indicating that ciliates and Eurytemora affinis were grazing on algae. (C) 2016 Elsevier GmbH. All rights reserved.

Pacific water contributes significantly to the Arctic Ocean freshwater budget. Recent increases in Arctic freshwater flux, also affected by the Pacific-derived Arctic water, impact the Atlantic overturning circulation with implications for global climate. The interannual variability of the Pacific water outflow remains poorly understood, partly due to different branches of the Pacific water flow in the Arctic Ocean. The shelfbreak current over the Beaufort Sea continental slope transports similar to 50% of the Pacific-derived water eastward along the Beaufort Sea continental slope towards the Canadian Archipelago. The oceanographic mooring deployed over the eastern Beaufort Sea continental slope in October 2003 recorded current velocities through depths of 28-108 m until September 2005. Data analysis revealed that these highly energetic currents have two different modes of depth-dependent behaviour. The downwelling-favourable wind associated with cyclones passing north of the Beaufort Sea continental slope toward the Canadian Archipelago generates depth-intensified shelfbreak currents with along-slope northeastward flow. A surface Ekman on-shore transport and associated increase of the sea surface heights over the shelf produce a cross-slope pressure gradient that drives an along-slope northeastward barotropic flow, in the same direction as the wind. In contrast, the upwelling-favourable wind associated with deep Aleutian Low cyclones over the Alaskan Peninsula and/or Aleutian Island Arc leads to surface-intensified currents with along-slope westward flow. This northeasterly wind generates a surface Ekman transport that moves surface waters offshore. The associated cross-slope pressure gradient drives an along-slope southwestward barotropic flow. The wind-driven barotropic flow generated by upwelling and downwelling is superimposed on the background bottom-intensified shelfbreak current. For downwelling, this flow amplifies the depth-intensified background baroclinic circulation with enhanced Pacific water transport towards the Canadian Archipelago. For upwelling, the shelfbreak current is reversed, which results in surface-intensified flow in the opposite direction. These results are supported by numerical simulations.

Source at https://doi.org/10.5194/bg-15-6503-2018. Diatoms are generally the dominant contributors to the Arctic Ocean spring bloom, which is a key event in regional food webs in terms of capacity for secondary production and organic matter export. Dissolved silicic acid is an obligate nutrient for diatoms and has been declining in the European Arctic since the early 1990s. The lack of regional silicon cycling information precludes understanding the consequences of such changes for diatom productivity during the Arctic spring bloom. This study communicates the results from a cruise in the European Arctic around Svalbard, which reports the first concurrent data on biogenic silica production and export, export of diatom cells, the degree of kinetic limitation by ambient silicic acid, and diatom contribution to primary production. Regional biogenic silica production rates were significantly lower than those achievable in the Southern Ocean and silicic acid concentration limited the biogenic silica production rate in 95 % of samples. Compared to diatoms in the Atlantic subtropical gyre, regional diatoms are less adapted for silicic acid uptake at low concentration, and at some stations during the present study, silicon kinetic limitation may have been intense enough to limit diatom growth. Thus, silicic acid can play a critical role in diatom spring bloom dynamics. The diatom contribution to primary production was variable, ranging from

The volume, heat and freshwater transports in the Fram Strait are estimated from geostrophic computations based on summer hydrographic data from 1984, 1997, 2002 and 2004. In these years, in addition to the usually sampled section along 79° N, a section between Greenland and Svalbard was sampled further north. Quasi-closed boxes bounded by the two sections and Greenland and Svalbard can then be formed. Applying conservation constraints on these boxes provides barotropic reference velocities. The net volume flux is southward and varies between 2 and 4 Sv. The recirculation of Atlantic water is about 2 Sv. Heat is lost to the atmosphere and the heat loss from the area between the sections averaged over the four years is about 10 TW. The net heat (temperature) transport is 20 TW northward into the Arctic Ocean, with large interannual differences. The mean net freshwater added between the sections is 40 mSv and the mean freshwater transport southward across 79° N is less than 60 mSv, indicating that most of the liquid freshwater leaving the Arctic Ocean through Fram Strait in summer is derived from sea ice melt in the northern vicinity of the strait. In 1997, 2001 and 2003 meridional sections along 0° longitude were sampled and in 2003 two smaller boxes can be formed, and the recirculation of Atlantic water in the strait is estimated by geostrophic computations and continuity constraints. The recirculation is weaker close to 80° N than close to 78° N, indicating that the recirculation is mainly confined to the south of 80° N. This is supported by the observations in 1997 and 2001, when only the northern part of the meridional section, from 79° N to 80° N, can be computed with the constraints applied. The recirculation is found strongest close to 79° N.

Global atmospheric methane concentrations have continued to rise in recent years, having already more than doubled since the Industrial Revolution. Further environmental change, especially climate change, in the twenty-first century has the potential to radically alter global methane fluxes. Importantly, changes in temperature, precipitation, and net primary production may induce positive climate feedback effects in dominant natural methane sources such as wetlands, soils, and aquatic ecosystems. Anthropogenic methane sources may also be impacted, with a risk of enhanced emissions from the energy, agriculture, and waste sectors. Here, we review the global sources of methane, the trends in fluxes by source and sector, and their possible evolution in response to future environmental change. We discuss ongoing uncertainties in flux estimation and projection, and highlight the great potential for multisector methane mitigation as part of wider global climate change policy.

20 pages, 6 figures, 1 table.-- This work is distributed under the Creative Commons Attribution 4.0 License, Pathways and timescales of water mass transport in the subpolar North Atlantic Ocean (SPNA) have been investigated by many studies due to their importance for the meridional overturning circulation and thus for the global ocean. In this sense, observational data on geochemical tracers provide complementary information to improve the current understanding of the circulation in the SPNA. To this end, we present the first simultaneous distribution of artificial 129I and 236U in 14 depth profiles and in surface waters along the GEOVIDE section covering a zonal transect through the SPNA in spring 2014. Our results show that the two tracers are distributed following the water mass structure and that their presence is largely influenced by the global fallout (GF) and liquid effluents discharged to north-western European coastal waters by the Sellafield and La Hague nuclear reprocessing plants (NRPs). As a result, 129I concentrations and 236U∕238U atom ratios and 129I∕236U atom ratios display a wide range of values: (0.2–256) × 107atkg−1 (40–2350) × 10−12 and 0.5–200, respectively. The signal from NRPs, which is characterised by higher 129I concentrations and 129I∕236U atom ratios compared to GF, is transported by Atlantic Waters (AWs) into the SPNA, notably by the East Greenland Current (EGC)/Labrador Current (LC) at the surface and by waters overflowing the Greenland–Scotland passage at greater depths. Nevertheless, our results show that the effluents from NRPs may also directly enter the surface of the eastern SPNA through the Iceland–Scotland passage or the English Channel/Irish Sea. The use of the 236U∕238U and 129I∕236U dual tracer approach further serves to discern Polar Intermediate Water (PIW) of Canadian origin from that of Atlantic origin, which carries comparably higher tracer levels due to NRPs (particularly 129I). The cascading of these waters appears to modify the water mass composition in the bottom of the Irminger and Labrador seas, which are dominated by Denmark Strait Overflow Water (DSOW). Indeed, PIW–Atlantic, which has a high level of 129I compared to 236U, appears to contribute to the deep Irminger Sea increasing the 129I concentrations in the realm of DSOW. A similar observation can be made for 236U for PIW entering through the Canadian Archipelago into the Labrador Sea. Several depth profiles also show an increase in 129I concentrations in near bottom waters in the Iceland and the West European basins that are very likely associated with the transport of the NRP signal by the Iceland–Scotland Overflow Water (ISOW). This novel result would support current modelling studies indicating the transport of ISOW into the eastern SPNA. Finally, our tracer data from 2014 are combined with published 129I data for the deep central Labrador Sea between 1993 and 2013. The results obtained from comparing simulated and measured 129I concentrations support the previously suggested two major transport pathways for the AWs in the SPNA, i.e. a short loop through the Nordic seas into the SPNA and a longer loop, which includes recirculation of the AWs in the Arctic Ocean before it enters the western SPNA, The GEOVIDE cruise was funded by the French National Research Agency (ANR-13-BS06-0014, ANR-12-PDOC-0025-01), the French National Center for Scientific Research (CNRS LEFE CYBER), the LabexMER (ANR-10-LABX-19), and Ifremer. This work was funded by the Ministerio de Economía y Competitividad of Spain (MDM2015-0552), the Generalitat de Catalunya (MERS 2017 SGR-1588) and consortium partners of the ETH Zurich Laboratory of Ion Beam Physics (EAWAG, EMPA, and PSI). Maxi Castrillejo was funded by a FPU PhD studentship (AP-2012-2901) from the Ministerio de Educación, Cultura y Deporte of Spain and the ETH Zurich Postdoctoral Fellowship Programme (17-2 FEL-30), co-funded by the Marie Curie Actions for People COFUND Programme. Núria Casacuberta’s research was funded by the AMBIZIONE grant (PZ00P2_154805) from the Swiss National Science Foundation. Maribel I. García-Ibáñez was supported by the Spanish Ministry of Economy and Competitiveness through the BOCATS (CTM2013-41048-P) project co-funded by the Fondo Europeo de Desarrollo Regional 2014–2020 (FEDER)

Arctic animals face dramatic habitat alteration due to ongoing climate change. Understanding how such species have responded to past glacial cycles can help us forecast their response to today's changing climate. Gray whales are among those marine species likely to be strongly affected by Arctic climate change, but a thorough analysis of past climate impacts on this species has been complicated by lack of information about an extinct population in the Atlantic. While little is known about the history of Atlantic gray whales or their relationship to the extant Pacific population, the extirpation of the Atlantic population during historical times has been attributed to whaling. We used a combination of ancient and modern DNA, radiocarbon dating and predictive habitat modelling to better understand the distribution of gray whales during the Pleistocene and Holocene. Our results reveal that dispersal between the Pacific and Atlantic was climate dependent and occurred both during the Pleistocene prior to the last glacial period and the early Holocene immediately following the opening of the Bering Strait. Genetic diversity in the Atlantic declined over an extended interval that predates the period of intensive commercial whaling, indicating this decline may have been precipitated by Holocene climate or other ecological causes. These first genetic data for Atlantic gray whales, particularly when combined with predictive habitat models for the year 2100, suggest that two recent sightings of gray whales in the Atlantic may represent the beginning of the expansion of this species' habitat beyond its currently realized range.

Ice algae are a key component in polar marine food webs and have an active role in large-scale biogeochemical cycles. They remain extremely under-sampled due to the coarse nature of traditional point sampling methods compounded by the general logistical limitations of surveying in polar regions. This study provides a first assessment of hyperspectral imaging as an under-ice remote-sensing method to capture sea-ice algae biomass spatial variability at the ice/water interface. Ice-algal cultures were inoculated in a unique inverted sea-ice simulation tank at increasing concentrations over designated cylinder enclosures and sparsely across the ice/water interface. Hyperspectral images of the sea ice were acquired with a pushbroom sensor attaining 0.9 mm square pixel spatial resolution for three different spectral resolutions (1.7, 3.4, 6.7 nm). Image analysis revealed biomass distribution matching the inoculated chlorophyll a concentrations within each cylinder. While spectral resolutions >6 nm hindered biomass differentiation, 1.7 and 3.4 nm were able to resolve spatial variation in ice algal biomass implying a coherent sensor selection. The inverted ice tank provided a suitable sea-ice analogue platform for testing key parameters of the methodology. The results highlight the potential of hyperspectral imaging to capture sea-ice algal biomass variability at unprecedented scales in a non-invasive way.

Formation of deep water in the high-latitude North Atlantic is important for the global meridional ocean circulation, and its variability in the past may have played an important role in regional and global climate change. Here we study ocean circulation associated with the last (de)glacial period, using water-column radiocarbon age reconstructions in the Faroe-Shetland Channel, southeastern Norwegian Sea, and from the Iceland Basin, central North Atlantic. The presence of tephra layer Faroe Marine Ash Zone II, dated to similar to 26.7 ka, enables us to determine that the middepth (1179m water depth) and shallow subsurface reservoir ages were similar to 1500 and 1100 C-14 years, respectively, older during the late glacial period compared to modern, suggesting substantial suppression of the overturning circulation in the Nordic Seas. During the late Last Glacial Maximum and the onset of deglaciation (similar to 20-18 ka), Nordic Seas overflow was weak but active. During the early deglaciation (similar to 17.5-14.5 ka), our data reveal large differences between C-14 ventilation ages that are derived from dating different benthic foraminiferal species: Pyrgo and other miliolid species yield ventilation ages >6000 C-14 years, while all other species reveal ventilation ages

Microorganisms are flushed from the Greenland Ice Sheet (GrIS) where they may contribute towards the nutrient cycling and community compositions of downstream ecosystems. We investigate meltwater microbial assemblages as they exit the GrIS from a large outlet glacier, and as they enter a downstream river delta during the record melt year of 2012. Prokaryotic abundance, flux and community composition was studied, and factors affecting community structures were statistically considered. The mean concentration of cells exiting the ice sheet was 8.30 x 10(4) cells mL(-1) and we estimate that approximate to 1.02 x 10(21) cells were transported to the downstream fjord in 2012, equivalent to 30.95 Mg of carbon. Prokaryotic microbial assemblages were dominated by Proteobacteria, Bacteroidetes, and Actinobacteria. Cell concentrations and community compositions were stable throughout the sample period, and were statistically similar at both sample sites. Based on our observations, we argue that the subglacial environment is the primary source of the river-transported microbiota, and that cell export from the GrIS is dependent on discharge. We hypothesise that the release of subglacial microbiota to downstream ecosystems will increase as freshwater flux from the GrIS rises in a warming world.

We characterized spatial patterns of surface sediment concentrations of seven polychlorinated biphenyls (PCBs), seven polycyclic aromatic hydrocarbons (PAHs), three chlorinated pesticides, and five metals in Norwegian waters and Skagerrak. In total, we analyzed 5036 concentrations of 22 chemical substances that were measured between 1986 and 2014 at 333 sampling sites by means of generalized additive models (GAMs). We found that GAMs with organic carbon content of the sediment and latitude and longitude as co-variates explained as ca. 75% of the variability of the contaminant sediment concentrations. For metals, a predominantly hotspot-driven spatial pattern was found, i.e., we identified historical pollution hotspots (e.g., Sorfjord in western Norway) for mercury, zinc, cadmium, and lead. Highest concentrations of PAHs and PCBs were found close to densely populated and industrialized regions, i.e., in the North Sea and in the Kattegat and Skagerrak. The spatial pattern of the PCBs suggests the secondary and diffuse atmospheric nature of their sources. Atmospheric inputs are the main sources of pollution for most organic chemicals considered, but north of the Arctic circle, we found that concentrations of PAHs increased from south to north most likely related to a combination of coal-eroding bedrock and the biological pump. The knowledge acquired in the present research is essential for developing effective remediation strategies that are consistent with international conventions on pollution control.

Biogeochemical processes associated with sea ice are still inadequately described and poorly represented in models, making it difficult to properly quantify the impacts of climate change in polar regions. Within the framework of the international Scientific Committee of Ocean Research (SCOR) working group 140, BEPSII, a community of sea-ice biogeochemical scientists established guidelines for the measurement of biogeochemical processes in sea ice, collated observed data, synthesized knowledge of sea-ice biogeochemical processes, and identified the feedbacks between biogeochemical and physical processes at the terrestrial-ocean-ice-snow-atmosphere interfaces and within the sea-ice matrix. Many of these results are presented in Elementa’s Special Feature on BEPSII. By bringing together experimentalists and modelers, major improvements of sea-ice biochemistry models have been achieved which are anticipated to affect models on micro- to global scales. However, large gaps still exist in our understanding of detailed biogeochemical processes in sea ice, their seasonal evolution and their interactions with surrounding environments. The BEPSII community recommends continued focus on the development of reproducible methods and techniques for reliable inter-study comparisons, to enhance our understanding in areas where gaps have been identified via coordinated process studies combining modeling tools, laboratory experiments and field studies, and on the use of such studies to develop conceptual models helping us to understand the overall system.

Archaeal communities represent a significant fraction of the Antarctic marine microbial plankton and surely play a relevant role in the proper functioning of the ecosystem. We studied the archaeal community structure in surface water samples from Potter Cove, Antarctica. Temporal and spatial variability was investigated along a whole year cycle using DGGE and 16S rRNA gene sequencing from clone libraries. Additionally, photosynthetic pigments, suspended particulate matter (SPM), salinity and temperature were measured. The multivariate analysis performed using diversity, dominance and richness indexes, and environmental data evidenced a seasonal pattern in the archaeal community and revealed that spring–summer samples clustered separately from autumn to winter ones. High salinity and high values of diversity and richness were related to autumn–winter samples, whereas the spring–summer samples were associated mainly with higher values of temperature, SPM, Chl-a, carotenoids and archaeal dominance. The phylogenetic analysis of five independent clone libraries (467 sequences) showed that 448 sequences fell into a clade containing Nitrosopumilus maritimus and other sequences of ammonia-oxidizing archaea which belong to the Thaumarchaeota phylum. A high fraction of these sequences (62 %) constituted a single cluster containing only highly similar Potter Cove representatives, which probably belong to the same species. Fifteen sequences were affiliated to a group closely related to the order Thermoplasmatales (Euryarchaeota). This work represents a first step towards obtaining a deep understanding of the structure of archaeal communities from Antarctic coastal marine environments and contributes to cover the current gap in knowledge of the dynamics of the archaeoplankton in the Antarctic seas.

Long-term monitoring of data of ambient mercury (Hg) on a global scale to assess its emission, transport, atmospheric chemistry, and deposition processes is vital to understanding the impact of Hg pollution on the environment. The Global Mercury Observation System (GMOS) project was funded by the European Commission (http://www.gmos.eu) and started in November 2010 with the overall goal to develop a coordinated global observing system to monitor Hg on a global scale, including a large network of ground-based monitoring stations, ad hoc periodic oceanographic cruises and measurement flights in the lower and upper troposphere as well as in the lower stratosphere. To date, more than 40 ground-based monitoring sites constitute the global network covering many regions where little to no observational data were available before GMOS. This work presents atmospheric Hg concentrations recorded worldwide in the framework of the GMOS project (2010-2015), analyzing Hg measurement results in terms of temporal trends, seasonality and comparability within the network. Major findings highlighted in this paper include a clear gradient of Hg concentrations between the Northern and Southern hemispheres, confirming that the gradient observed is mostly driven by local and regional sources, which can be anthropogenic, natural or a combination of both. Fil: Sprovieri, Francesca. Institute of Atmospheric Pollution Research; Italia Fil: Pirrone, Nicola. Institute of Atmospheric Pollution Research; Italia Fil: Bencardino, Mariantonia. Institute of Atmospheric Pollution Research; Italia Fil: D'Amore, Francesco. Institute of Atmospheric Pollution Research; Italia Fil: Carbone, Francesco. Institute of Atmospheric Pollution Research; Italia Fil: Cinnirella, Sergio. Institute of Atmospheric Pollution Research; Italia Fil: Mannarino, Valentino. Institute of Atmospheric Pollution Research; Italia Fil: Landis, Matthew. US Environmental Protection Agency; Estados Unidos Fil: Ebinghaus, Ralf. Helmholtz Zentrum; Alemania Fil: Weigelt, Andreas. Helmholtz Zentrum; Alemania Fil: Brunke, Ernst Günther. South African Weather Service; Sudáfrica Fil: Labuschagne, Casper. South African Weather Service; Sudáfrica Fil: Martin, Lynwill. South African Weather Service; Sudáfrica Fil: Munthe, John. Swedish Environmental Research Inst. Ltd.; Suecia Fil: Wängberg, Ingvar. Swedish Environmental Research Inst. Ltd.; Suecia Fil: Artaxo, Paulo. Universidade de Sao Paulo; Brasil Fil: Morais, Fernando. Universidade de Sao Paulo; Brasil Fil: De Melo Jorge Barbosa, Henrique. Universidade de Sao Paulo; Brasil Fil: Brito, Joel. Universidade de Sao Paulo; Brasil Fil: Cairns, Warren. Universita' Ca' Foscari Di Venezia; Italia Fil: Barbante, Carlo. Universita' Ca' Foscari Di Venezia; Italia. Institute for the Dynamics of Environmental Processes; Italia Fil: Dieguez, Maria del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina Fil: Garcia, Patricia Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina Fil: Aurélien, Dommergue. Centre National de la Recherche Scientifique; Francia. University Grenoble Alpes; Francia Fil: Angot, Helene. Centre National de la Recherche Scientifique; Francia. University Grenoble Alpes; Francia Fil: Magand, Olivier. Centre National de la Recherche Scientifique; Francia. University Grenoble Alpes; Francia Fil: Skov, Henrik. University Aarhus; Dinamarca Fil: Horvat, Milena. Jožef Stefan Institute; Eslovenia Fil: Kotnik, Jože. Jožef Stefan Institute; Eslovenia Fil: Alana Read, Katie. University of York; Reino Unido Fil: Mendes Neves, Luis. Cape Verde Observatory; Brasil Fil: Manfred Gawlik, Bernd. Joint Research Centre; Italia Fil: Sena, Fabrizio. Joint Research Centre; Italia Fil: Mashyanov, Nikolay. St. Petersburg State University; Rusia Fil: Obolkin, Vladimir. Limnological Institute SB RAS; Rusia Fil: Wip, Dennis. University of Suriname; Surinam Fil: Bin Feng, Xin. Institute Of Geochemistry Chinese Academy Of Sciences; China Fil: Zhang, Hui. Institute Of Geochemistry Chinese Academy Of Sciences; China Fil: Fu, Xuewu. Institute Of Geochemistry Chinese Academy Of Sciences; China Fil: Ramachandran, Ramesh. Anna University; India Fil: Cossa, Daniel. Centre Méditerranée; Francia Fil: Knoery, Joël. Centre Atlantique; Francia Fil: Marusczak, Nicolas. Centre Méditerranée; Francia Fil: Nerentorp, Michelle. Chalmers University Of Technology; Suecia Fil: Norstrom, Claus. University Aarhus; Dinamarca

Recent hypotheses, based on atmospheric records and models, suggest that permafrost carbon (PF-C) accumulated during the last glaciation may have been an important source for the atmospheric CO2 rise during post-glacial warming. However, direct physical indications for such PF-C release have so far been absent. Here we use the Laptev Sea (Arctic Ocean) as an archive to investigate PF-C destabilization during the last glacial–interglacial period. Our results show evidence for massive supply of PF-C from Siberian soils as a result of severe active layer deepening in response to the warming. Thawing of PF-C must also have brought about an enhanced organic matter respiration and, thus, these findings suggest that PF-C may indeed have been an important source of CO2 across the extensive permafrost domain. The results challenge current paradigms on the post-glacial CO2 rise and, at the same time, serve as a harbinger for possible consequences of the present-day warming of PF-C soils., Atmospheric CO2 increases during the last deglaciation have been linked to the destabilisation of permafrost carbon reservoirs. Here, using a sediment core from the Laptev Sea, Tesi et al. indicate a massive supply of permafrost carbon was released from Siberia following active layer deepening.

The characteristics of the mid-Pliocene warm period (mPWP: 3.264–3.025 Ma BP) have been examined using geological proxies and climate models. While there is agreement between models and data, details of regional climate differ. Uncertainties in prescribed forcings and in proxy data limit the utility of the interval to understand the dynamics of a warmer than present climate or evaluate models. This uncertainty comes, in part, from the reconstruction of a time slab rather than a time slice , where forcings required by climate models can be more adequately constrained. Here, we describe the rationale and approach for identifying a time slice(s) for Pliocene environmental reconstruction. A time slice centred on 3.205 Ma BP (3.204–3.207 Ma BP) has been identified as a priority for investigation. It is a warm interval characterized by a negative benthic oxygen isotope excursion (0.21–0.23‰) centred on marine isotope stage KM5c (KM5.3). It occurred during a period of orbital forcing that was very similar to present day. Climate model simulations indicate that proxy temperature estimates are unlikely to be significantly affected by orbital forcing for at least a precession cycle centred on the time slice, with the North Atlantic potentially being an important exception.

Freshwater (FW) fluxes from river runoff and precipitation minus evaporation for the pan Arctic seas are relatively well documented and prescribed in ocean GCMs. Fluxes from Greenland on the other hand are generally ignored altogether, despite their potential impacts on ocean circulation and marine biology. Here, we present a reconstruction of the spatially distributed FW flux from Greenland for 1958-2010. We find a modest increase into the Arctic Ocean during this period. Fluxes into the Irminger Basin, however, have increased by fifty percent (6.30.5km3yr-2) in less than twenty years. This greatly exceeds previous estimates. For the ice sheet as a whole the rate of increase since 1992 is 16.91.8km3yr-2. The cumulative FW anomaly since 1995 is 3200358km3, which is about a third of the magnitude of the Great Salinity Anomaly (GSA) of the 1970s. If this trend continues into the future, the anomaly will exceed that of the GSA by about 2025. © 2012. American Geophysical Union. All Rights Reserved.

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Macdonald, Robie W. Gratton, Yves Macdonald, Robie/A-7896-2012 Macdonald, Robie/0000-0002-1141-8520 CCGS Amundsen; CASES (Canadian Arctic Shelf Exchange Study) NSERC network (Natural Sciences and Engineering Research Council of Canada); Canadian Fund for Innovation; Canadian Coast Guard; Department of Fisheries and Oceans Canada; NSERC Discovery We thank the officers and crew of the CCGS Amundsen for their support and dedication to the CASES expedition. We are indebted to Constance Guignard, Nes Sutherland, Pascale Collin, Simon Belanger, Jens Ehn, Mike Arychuk and Owen Owens for their care and perseverance in collecting and analyzing the TA, TIC and pH samples at sea. Thanks must go to the CTD data acquisition group for these basic but critical measurements and the calibration of the various probes. Most of the plots and maps in this study were created with the ODV Software [Schlitzer, 2009]. We also thank A. Proshutinsky and two anonymous reviewers who provided constructive comments that helped to improve our manuscript. This study was funded through the CASES (Canadian Arctic Shelf Exchange Study) NSERC network (Natural Sciences and Engineering Research Council of Canada) and a Canadian Fund for Innovation grant to support the upgrade and operation of the CCGS Amundsen. Additional financial contributions were provided by the Canadian Coast Guard, the Strategic Science Fund of the Department of Fisheries and Oceans Canada, and NSERC Discovery grants to A. Mucci and Y. Gratton. 10 AMER GEOPHYSICAL UNION WASHINGTON J GEOPHYS RES-OCEANS; We examined the seasonal variability of water mass distributions in the southeastern Beaufort Sea from data collected between September 2003 and August 2004. Salinity, total alkalinity (TA) and isotopic composition (delta O-18) of seawater were used together as tracers of freshwater input, i.e., meteoric water and sea ice meltwater. We used an optimum multiparameter analysis to identify the different water masses, including the Mackenzie River, sea ice melt (SIM), winter polar mixed layer (PML), upper halocline water (UHW) with core salinity of 33.1 psu (Pacific origin) and Atlantic Water. Computed values of CO2 fugacity in seawater (fCO(2)-sw) show that the surface mixed layer (SML) remains mostly undersaturated (328 +/- 55 mu atm, n = 552) with respect to the average atmospheric CO2 concentration (380 +/- 5 mu atm) over the study period. The influence of the Mackenzie River (fCO(2-SW) > 500 mu atm) was relatively small in the southeastern Beaufort Sea, and significant fractions were only observed on the inner Mackenzie Shelf. The contribution of sea ice melt (fCO(2-SW) < 300 mu atm) to the SML could reach 30% beyond the shelf break and close to the ice pack in autumn. The density of the PML increased through the winter due to cooling and brine rejection. The winter PML reached a maximum depth of 70 m in late April. The UHW (fCO(2-SW) > 600 mu atm) was usually located between 120 and 180 m depth, but could contribute to the SML during wind-driven upwelling events, in summer and autumn, and during brine-driven eddies, in winter.

Background: The deep sea floor is considered one of the most diverse ecosystems on Earth. Recent environmental DNA surveys based on clone libraries of rRNA genes confirm this observation and reveal a high diversity of eukaryotes present in deep-sea sediment samples. However, environmental clone-library surveys yield only a modest number of sequences with which to evaluate the diversity of abyssal eukaryotes. Methodology/Principal Findings: Here, we examined the richness of eukaryotic DNA in deep Arctic and Southern Ocean samples using massively parallel sequencing of the 18S ribosomal RNA (rRNA) V9 hypervariable region. In very small volumes of sediments, ranging from 0.35 to 0.7 g, we recovered up to 7,499 unique sequences per sample. By clustering sequences having up to 3 differences, we observed from 942 to 1756 Operational Taxonomic Units (OTUs) per sample. Taxonomic analyses of these OTUs showed that DNA of all major groups of eukaryotes is represented at the deep-sea floor. The dinoflagellates, cercozoans, ciliates, and euglenozoans predominate, contributing to 17%, 16%, 10%, and 8% of all assigned OTUs, respectively. Interestingly, many sequences represent photosynthetic taxa or are similar to those reported from the environmental surveys of surface waters. Moreover, each sample contained from 31 to 71 different metazoan OTUs despite the small sample volume collected. This indicates that a significant faction of the eukaryotic DNA sequences likely do not belong to living organisms, but represent either free, extracellular DNA or remains and resting stages of planktonic species. Conclusions/Significance: In view of our study, the deep-sea floor appears as a global DNA repository, which preserves genetic information about organisms living in the sediment, as well as in the water column above it. This information can be used for future monitoring of past and present environmental changes. French ANR Aquaparadox; ANR DeepOases; Swiss National Science Foundation [31003A-125372]; WM Keck foundation SNSF /Project funding info:eu-repo/semantics/publishedVersion

A colonisation experiment was performed in situ at 2500 m water depth at the Arctic deep-sea long-term observatory HAUSGARTEN to determine the response of deep-sea nematodes to disturbed, newly available patches, enriched with organic matter. Cylindrical tubes,laterally covered with a 500 µm mesh, were filled with azoic deep-sea sediment and 13C-labelled food sources diatoms and bacteria). After 10 days of incubation the tubes were analysed for nematode response in terms of colonisation and uptake. Nematodes actively colonised the tubes,however with densities that only accounted for a maximum of 2.13% (51 ind.10 cm-2) of the ambient nematode assemblages. Densities did not differ according to the presence or absence of organic matter, nor according to the type of organic matter added. The fact that the organic matter did not function as an attractant to nematodes was confirmed by the absence of notable 13C assimilation by the colonising nematodes. Overall, colonisationappears to be a process that yields reproducible abundance and diversity patterns, with certain taxa showing more efficiency. Together with the high variability between the colonising nematode assemblages, this lends experimental support to the existence of a spatio-temporal mosaic that emerges from highly localised, partially stochastic community dynamics.

Dissolved aluminium (Al) occurs in a wide range of concentrations in the world oceans. The concentrations of Al in the Southern Ocean are among the lowest ever observed. An all-titanium CTD sampling system makes it possible to study complete deep ocean sections of Al and other trace elements with the same high vertical resolution of 24 depths as normal for traditional CTD/Rosette sampling. Overall, 470 new data points of Al are reported for 22 full depth stations and 24 surface sampling positions along one transect. This transect consisted of 18 stations on the zero meridian proper from 51 degrees 57'S until 69 degrees 24'S, and 4 stations somewhat to the northeast towards Cape Town from 42 degrees 20'S, 09 degrees E to 50 degrees 17'S, 01 degrees 27'E. The actual concentrations of Al in the Southern Ocean were lower than previously reported. The concentration of Al in the upper 25 m was relatively elevated with an average concentration of 0.71 nM (n=22; S.D.=0.43 nM), most likely due to atmospheric input by a suggested combination of direct atmospheric (wet and dry) input and indirect atmospheric input via melting sea ice. Below the surface waters there was a distinct Al minimum with an average concentration of 0.33 nM (n=22: S.D.=0.13 nM) at an average depth of 120 m. In the deep southern-most Weddell Basin the concentration of Al increased with depth to similar to 0.8 nM at 4000 m, and a higher concentration of similar to 1.5 nM in the similar to 4500-5200 m deep Weddell Sea Bottom Water. Over the Bouvet triple junction region, where three deep ocean ridges meet, the concentration of Al increased to similar to 1.4 nM at about 2000 m depth over the ridge crest. In the deep basin north of the Bouvet region the concentration of Al increased to higher deep values of 4-6 nM due to influence of North Atlantic Deep Water. In general the intermediate and deep distribution of Al results from the mixing of water masses with different origins, the formation of deep water and additional input from sedimentary sources at sea floor elevations. No significant correlation between Al and silicate (Si) was observed. This is in contrast to some other ocean regions. In the Southern Ocean the supply of Al is extremely low and any signal from Al uptake and dissolution with biogenic silica is undetectable against the high dissolved Si and low dissolved Al concentrations. Here the Al-Si relation in the deep ocean is uncoupled. This is due to the scavenging and subsequent loss of the water column of Al, whereas the concentration of Si increases in the deep ocean due to its input from deep dissolution of biogenic diatom frustules settling from the surface layer. (C) 2011 Elsevier Ltd. All rights reserved.

Benthic foraminifera were investigated from 20 grab samples collected from a large marine embayment, Disko Bugt, along the west Greenland margin. Agglutinated and calcareous foraminifera were found throughout Disko Bugt, with agglutinated species dominating 19 out of the 20 samples. The most common species are Adercotryma glomerata, Spiroplectammina biformis, Textularia earlandi, Cribrosto- moides crassimargo and Reophax fusiformis. Six faunal assemblage zones were identified from cluster analysis and detrended correspondence analysis. The relationship between the foraminifera and environmental variables was investigated using canonical correspondence analysis. From this analysis, bottom water salinity and water depth were identified as the most important environmental variables explaining the fora- miniferal assemblages. This result suggests water mass characteristics in Disko Bugt are an important control on the benthic foraminiferal assemblage zones. Where the warm and saline West Greenland Current water mass impinges on the seafloor, the assemblage is dominated by A. glomerata, T. earlandi, R. fusiformis and Reophax pilulifer. Sites with the cold, lower salinity Polar Water mass at the seafloor are dominated by S. biformis and A. glomerata, with common Cuneata arctica and C. crassimargo. In shallow locations with a relatively warm and low salinity surface water mass and coarse sediments the fauna is dominated by Cibicides lobatulus. In similar hydrographic locations with fine-grained sediments a mixed faunal assemblage dominated by Ammos- calaria pseudospiralis and Eggerella advena is found.