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  • Open Access English
    Authors: 
    Van Audenhaege, Loïc; Broad, Emmeline; Hendry, Katharine R; Huvenne, Veerle A I;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
    Project: EC | iAtlantic (818123), EC | ICY-LAB (678371)

    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.

  • Open Access English
    Authors: 
    Roberts, Jenny; Gottschalk, Julia; Skinner, Luke C; Peck, Victoria L; Kender, Sev; Elderfield, Henry; Waelbroeck, Claire; Vázquez Riveiros, Natalia; Hodell, David A;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
    Project: EC | ACCLIMATE (339108), UKRI | The bi-polar seesaw and C... (NE/J010545/1), EC | NEWLOG (267931)

    Explanations of the glacial-interglacial variations in atmospheric pCO2 invoke a significant role for the deep ocean in the storage of CO2. Deep-ocean density stratification has been proposed as a mechanism to promote the storage of CO2 in the deep ocean during glacial times. A wealth of proxy data supports the presence of a "chemical divide" between intermediate and deep water in the glacial Atlantic Ocean, which indirectly points to an increase in deep-ocean density stratification. However, direct observational evidence of changes in the primary controls of ocean density stratification, i.e., temperature and salinity, remain scarce. Here, we use Mg/Ca-derived seawater temperature and salinity estimates determined from temperature-corrected d18O measurements on the benthic foraminifer Uvigerina spp. from deep and intermediate water-depth marine sediment cores to reconstruct the changes in density of sub-Antarctic South Atlantic water masses over the last deglaciation (i.e., 22-2 ka before present). We find that a major breakdown in the physical density stratification significantly lags the breakdown of the deep-intermediate chemical divide, as indicated by the chemical tracers of benthic foraminifer d13C and foraminifer/coral 14C. Our results indicate that chemical destratification likely resulted in the first rise in atmospheric pCO2, whereas the density destratification of the deep South Atlantic lags the second rise in atmospheric pCO2 during the late deglacial period. Our findings emphasize that the physical and chemical destratification of the ocean are not as tightly coupled as generally assumed.

  • Open Access English
    Authors: 
    De Schepper, Stijn; Ray, Jessica L; Skaar, Katrine S; Sadatzki, Henrik; Ijaz, Umer Zeeshan; Stein, Ruediger; Larsen, Aud;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
    Project: UKRI | Undestanding microbial co... (NE/L011956/1), EC | ICE2ICE (610055), EC | AGENSI (818449)

    At Site GS15-198-38, Greenland Sea, we analysed the surface sample (from a multicore) and eight Late Quaternary samples from a Calypso core. The age model for the Calypso core GS15-198-38CC is based on seven AMS 14C ages down to 345 cm, and a 5-cm resolution N. pachyderma sinistral isotope stratigraphy (1) below that level. We analysed the palynology, generated organic biomarker data (including IP25, sterols) and performed quantitative PCR (droplet digital PCR, ddPCR) of the sympagic dinoflagellate Polarella glacialis. The main funding for this project came from:Research Council of Norway project 268062 (Environmental ancient DNA as proxy for sea ice reconstructions - aDNAPROX)Research Council of Norway project 273455/E10 (KLIMAFORSK mobility) Additional funding came from:Bjerknes Centre for Climate ResearchNatural Environment Research Council (NERC) Independent Research Fellowship NE/L011956/1Lord Kelvin Adam Smith Leadership Fellowship (University of Glasgow)European Research Council under the European Community's Seventh Framework Program (FP7/2007-2013) / ERC grant agreement 610055 as part of the ice2ice project

  • Open Access English
    Authors: 
    Hendry, Katharine R;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
    Project: EC | ICY-LAB (678371)

    DY081 was the first fieldwork component of a European Research Council funded project, ICY-LAB, led by Dr. K. Hendry from the University of Bristol to study nutrient cycling in the North Atlantic. This data release contains seawater bottle data collected during DY081 by standard CTD rosette, remotely operated vehicle and Tow fish, together with ancillary, processed sensor data at the bottle opening depths. Four sites of interest were surveyed: Orphan Knoll off the coast of Newfoundland, and Nuuk, Nasrsaq, and Cape Farewell off southwest Greenland. Description of the data available is given in the Data Documentation file (see Further details).

  • Open Access English
    Authors: 
    Ng, Hong Chin; Cassarino, Lucie; Pickering, Rebecca A; Woodward, E Malcolm S; Hammond, Samantha J; Hendry, Katharine R;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
    Project: EC | ICY-LAB (678371)

    The dataset contains pore water and core incubation silicic acid concentration and isotope measurements, sponge silicon isotope measurements, and pore water major and trace elemental concentrations obtained from seven sediment cores collected from the Greenland margin and the Labrador Sea. The samples were collected as part of the European Research Council project ICY-LAB (ERC-2015-STG grant agreement number 678371).

  • Open Access English
    Authors: 
    De Clippele, Laurence Helene; Huvenne, Veerle A I; Orejas, Covadonga; Lundälv, Tomas; Fox, Alan; Hennige, S J; Roberts, J Murray;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
    Project: EC | ATLAS (678760), UKRI | Coral pH regulation and c... (NE/K009028/2), EC | ASSEMBLE (227799), UKRI | Coral pH regulation and c... (NE/K009028/1), EC | CODEMAP (258482)

    This data was used in a study that demonstrates how cold-water coral morphology and habitat distribution are shaped by local hydrodynamics, using high-definition video from Tisler Reef, an inshore reef in Norway. A total of 334 video frames collected on the north-west (NW) and south-east (SE) side of the reef were investigated for Lophelia pertusa coral cover and morphology and for the cover of the associated sponges Mycale lingua and Geodia sp. Our results showed that the SE side was a better habitat for L. pertusa (including live and dead colonies). Low cover of Geodia sp. was found on both sides of Tisler Reef. In contrast, Mycale lingua had higher percentage cover, especially on the NW side of the reef. Bush-shaped colonies of L. pertusa with elongated branches were the most abundant coral morphology on Tisler Reef. The highest abundance and density of this morphology were found on the SE side of the reef, while a higher proportion of cauliflower-shaped corals with short branches were found on the NW side. The proportion of very small L. pertusa colonies was also significantly higher on the SE side of the reef. The patterns in coral spatial distribution and morphology were related to local hydrodynamics—there were more frequent periods of downwelling currents on the SE side—and to the availability of suitable settling substrates. These factors make the SE region of Tisler Reef more suitable for coral growth. Understanding the impact of local hydrodynamics on the spatial extent and morphology of coral, and their relation to associated organisms such as sponges, is key to understanding the past and future development of the reef.

  • Open Access English
    Authors: 
    Tyrrell, Toby; Charalampopoulou, Anastasia;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
    Project: EC | EPOCA (211384), UKRI | A Carbon and transient tr... (NE/F01242X/1), UKRI | What factors control cocc... (NE/F015054/1)

    Although coccolithophores are not as numerically common or as diverse in the Southern Ocean as they are in subpolar waters of the North Atlantic, a few species, such as Emiliania huxleyi, are found during the summer months. Little is actually known about the calcite production (CP) of these communities or how their distribution and physiology relate to environmental variables in this region. In February 2009, we made observations across Drake Passage (between South America and the Antarctic Peninsula) of coccolithophore distribution, CP, primary production, chlorophyll a and macronutrient concentrations, irradiance and carbonate chemistry. Although CP represented less than 1 % of total carbon fixation, coccolithophores were widespread across Drake Passage. The B/C morphotype of E. huxleyi was the dominant coccolithophore, with low estimates of coccolith calcite (~0.01 pmol C coccolith-1) from biometric measurements. Both cell-normalised calcification (0.01-0.16 pmol C cell-1 d-1) and total CP (< 20 µmol C m-3 d-1) were much lower than those observed in the subpolar North Atlantic where E. huxleyi morphotype A is dominant. However, estimates of coccolith production rates were similar (0.1 1.2 coccoliths cell-1 h-1) to previous measurements made in the subpolar North Atlantic. A multivariate statistical approach found that temperature and irradiance together were best able to explain the observed variation in species distribution and abundance (Spearman's rank correlation p = 0.4, p < 0.01). Rates of calcification per cell and coccolith production, as well as community CP and E. huxleyi abundance, were all positively correlated (p < 0.05) to the strong latitudinal gradient in temperature, irradiance and calcite saturation states across Drake Passage. Broadly, our results lend support to recent suggestions that coccolithophores, especially E. huxleyi, are advancing polewards. However, our in situ observations indicate that this may owe more to sea-surface warming and increasing irradiance rather than increasing CO2 concentrations. This data was collected during a cruise across Drake Passage in the Southern Ocean in February 2009. This data consists of coccolithophore abundance, calcification and primary production rates, carbonate chemistry parameters and ancillary data of macronutrients, chlorophyll-a, average mixed layer irradiance, daily irradiance above the sea surface, euphotic and mixed layer depth, temperature and salinity.

  • Open Access English
    Authors: 
    Hunter, William Ross; Jamieson, Alan J; Huvenne, Veerle A I; Witte, Ursula;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
    Project: EC | HERMIONE (226354), UKRI | Doctoral Training Grant (... (NE/G523904/1), EC | CODEMAP (258482)

    The Whittard canyon is a branching submarine canyon on the Celtic continental margin, which may act as a conduit for sediment and organic matter (OM) transport from the European continental slope to the abyssal sea floor. In situ stable-isotope labelling experiments (JC36-042-Spre01; JC36-100-Spre01) were conducted in the eastern and western branches of the Whittard canyon testing short term (3 - 7 day) responses of sediment communities to deposition of nitrogen-rich marine and nitrogen-poor terrigenous phytodetritus. Isotopic labels were traced into faunal biomass and bulk sediments, and the bacterial polar lipid fatty acids (PLFAs). These data files provide the data on macrofaunal and bacterial uptake of the isotopically-labelled organic carbon and nitrogen, and macrofaunal community composition at the two stations within the Whittard canyon

  • Open Access English
    Authors: 
    Hillenbrand, Claus-Dieter; Smith, James A; Hodell, David A; Greaves, Mervyn; Poole, Christopher R; Kender, Sev; Williams, Mark; Andersen, Thorbjørn Joest; Jernas, Patrycja E; Elderfield, Henry; +5 more
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
    Project: EC | NEWLOG (267931), UKRI | Assessing the role of oce... (NE/M013081/1)

    Glaciological and oceanographic observations coupled with numerical models show that warm Circumpolar Deep Water (CDW) incursions onto the West Antarctic continental shelf cause melting of the undersides of floating ice shelves. Because these ice shelves buttress glaciers feeding into them, their ocean-induced thinning is driving Antarctic ice-sheet retreat today. Here we present a multi-proxy data based reconstruction of variability in CDW inflow to the Amundsen Sea sector, the most vulnerable part of the West Antarctic Ice Sheet, during the Holocene epoch (from 11.7 thousand years ago to the present). The chemical compositions of foraminifer shells and benthic foraminifer assemblages in marine sediments indicate that enhanced CDW upwelling, controlled by the latitudinal position of the Southern Hemisphere westerly winds, forced deglaciation of this sector from at least 10,400 years ago until 7,500 years ago - when an ice-shelf collapse may have caused rapid ice-sheet thinning further upstream - and since the 1940s. These results increase confidence in the predictive capability of current ice-sheet models.

  • Open Access English
    Authors: 
    Suggett, David J; Hall-Spencer, Jason M; Rodolfo-Metalpa, Riccardo; Boatman, Toby G; Payton, Ross; Pettay, D Tye; Johnson, Vivienne R; Warner, Mark E; Lawson, Tracy;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
    Project: EC | MEDSEA (265103), UKRI | A community metabolism ap... (NE/G020116/1), NSF | Collaborative Research - ... (1040940)

    Increased seawater pCO2, and in turn 'ocean acidification' (OA), is predicted to profoundly impact marine ecosystem diversity and function this century. Much research has already focussed on calcifying reef-forming corals (Class: Anthozoa) that appear particularly susceptible to OA via reduced net calcification. However, here we show that OA-like conditions can simultaneously enhance the ecological success of non-calcifying anthozoans, which not only play key ecological and biogeochemical roles in present day benthic ecosystems but also represent a model organism should calcifying anthozoans exist as less calcified (soft-bodied) forms in future oceans. Increased growth (abundance and size) of the sea anemone (Anemonia viridis) population was observed along a natural CO2 gradient at Vulcano, Italy. Both gross photosynthesis (PG) and respiration (R) increased with pCO2 indicating that the increased growth was, at least in part, fuelled by bottom up (CO2 stimulation) of metabolism. The increase of PG outweighed that of R and the genetic identity of the symbiotic microalgae (Symbiodinium spp.) remained unchanged (type A19) suggesting proximity to the vent site relieved CO2 limitation of the anemones' symbiotic microalgal population. Our observations of enhanced productivity with pCO2, which are consistent with previous reports for some calcifying corals, convey an increase in fitness that may enable non-calcifying anthozoans to thrive in future environments, i.e. higher seawater pCO2. Understanding how CO2-enhanced productivity of non- (and less-) calcifying anthozoans applies more widely to tropical ecosystems is a priority where such organisms can dominate benthic ecosystems, in particular following localized anthropogenic stress.