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  • Open Access English
    Authors: 
    Huse, Geir;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
    Project: EC | EURO-BASIN (264933)

    Acoustic estimates of herring and blue whiting abundance were obtained during the surveys using the Simrad ER60 scientific echosounder. The allocation of NASC-values to herring, blue whiting and other acoustic targets were based on the composition of the trawl catches and the appearance of echo recordings. To estimate the abundance, the allocated NASC -values were averaged for ICES-squares (0.5° latitude by 1° longitude). For each statistical square, the unit area density of fish (rA) in number per square nautical mile (N*nm-2) was calculated using standard equations (Foote et al., 1987; Toresen et al., 1998). To estimate the total abundance of fish, the unit area abundance for each statistical square was multiplied by the number of square nautical miles in each statistical square and then summed for all the statistical squares within defined subareas and over the total area. Biomass estimation was calculated by multiplying abundance in numbers by the average weight of the fish in each statistical square then summing all squares within defined subareas and over the total area. The Norwegian BEAM soft-ware (Totland and Godø 2001) was used to make estimates of total biomass.

  • Open Access English
    Authors: 
    Dziadek, Ricarda;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science

    This dataset compiles in-situ temperature measurements for geothermal heat flow estimates and water temperature profiles of the water column, extracted from Miniaturized Temperature data-Logger (MTL). The data were collected during RV POLARSTERN cruise PS104 in 2017 in Amundsen Sea.

  • Open Access English
    Authors: 
    Waska, Hannelore; Brumsack, Hans-Jürgen; Massmann, Gudrun; Koschinsky, Andrea; Schnetger, Bernhard; Simon, Heike; Dittmar, Thorsten;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science

    Data from pore water (subterranean estuary) and seawater from Spiekeroog south (near ICBM time series station and campsite, 53°45'13.5"N 7°40'22.5"E) and west beach ("Sturmeck", 53°46'10.0"N 7°40'26.2"E). South beach data were collected in August 2012, and west beach data were collected in November 2012. Sample abbreviations: SB=South Beach, WB=West Beach. DUNE=most landward station near dunes, MIX=mid-way station between dune base and low water line, LTWL=low tide water line. Pore water (DUNE, MIX, LTWL) sample collection was conducted at different sediment depths (50, 100, 150 cm below sediment surface). Stainless steel push-point lancets were insetred into the sediment, and pore water was withdrawn via vacuum (hand pumps) into nalgene polycarbonate bottles. Filtration was done using inline PES cartridge filters. The vacuum bottles were argon gas-flushed to avoid oxygen contamination. Sea water (SW) was collected with polycarbonate bottles and from LDPE seepage meter bags (SP) and filtered upon return to the laboratory (same day, PES filter cartridges). Sample collection was trace organic and metal clean (soaking and rinsing of bottles, tubing, and filters with diluted HNO3 and HCl suprapur), with sample materials consisting of polyethylene, polypropylene, and polycarbonate. Solid-phase extraction was done with BOND Elut PPL cartridges and elution with Methanol Optima grade. Measurements were done with VA Computrace 757 (Cu ligand concentrations and stability constants), HR-ICP-MS (Cu, Fe, and Mn concentrations), FT-ICR-MS (DOM), spectrophotometry (nutrients), and TOC analyzer (DOC and TDN). Trace metal concentrations (Fe, Cu, Mn) and speciation (oxidation state, size fractions, and organic association), as well as nitrogen species and concentrations: "Spiekeroog beach subterranean estuary environmental data". Concentrations (µM or nM) are denoted in the headers. CuL1=Cu-binding ligands concentrations (nM), logK1=Cu-binding ligand stability constant. Molecular composition of dissolved organic matter and associated Fe and Cu: "Spiekeroog beach STE_ESI_x_Crosstab_x". pos & neg = positive and negative ionization mode. BSA & NWA = basic/strong acidic and neutral/weak acidic, refer to the extracted DOM fraction. Processed figures and tables based on the original data are published here: https://doi.org/10.1016/j.gca.2019.06.004

  • Open Access English
    Authors: 
    Tessin, Allyson; März, Christian; Kędra, Monika; Matthiessen, Jens; Morata, Nathalie; Nairn, Michael; O'Regan, Matthew; Peeken, Ilka;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
    Project: EC | PaNDA (709175)

    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.

  • Open Access English
    Authors: 
    Robinson, Tiera-Brandy; Stolle, Christian; Wurl, Oliver;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science

    Biochemical data from 3 different regions; Cape Verde, the Baltic Sea, and Norwegian fjords/Sea. discreet samples for TEP, Chl a, POC, PON and nutrients as well as 2 and 24 hour average data on sea state parameters; temperature, salinity, PAR and wind speed. Vertical profile data for TEP, POC, TCN, small autotrophs and Chl a are also presented for depths of 0-2m, sampled in the Baltic and Norwegian Seas.

  • 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: 
    Barker, Stephen; Cacho, Isabel; Benway, Heather M; Tachikawa, Kazuyo;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science

    As part of the Multi-proxy Approach for the Reconstruction of the Glacial Ocean (MARGO) incentive, published and unpublished temperature reconstructions for the Last Glacial Maximum (LGM) based on planktonic foraminiferal Mg/Ca ratios have been synthesised and made available in an online database. Development and applications of Mg/Ca thermometry are described in order to illustrate the current state of the method. Various attempts to calibrate foraminiferal Mg/Ca ratios with temperature, including culture, trap and core-top approaches have given very consistent results although differences in methodological techniques can produce offsets between laboratories which need to be assessed and accounted for where possible. Dissolution of foraminiferal calcite at the sea-floor generally causes a lowering of Mg/Ca ratios. This effect requires further study in order to account and potentially correct for it if dissolution has occurred. Mg/Ca thermometry has advantages over other paleotemperature proxies including its use to investigate changes in the oxygen isotopic composition of seawater and the ability to reconstruct changes in the thermal structure of the water column by use of multiple species from different depth and or seasonal habitats. Presently available data are somewhat limited to low latitudes where they give fairly consistent values for the temperature difference between Late Holocene and the LGM (2-3.5 °C). Data from higher latitudes are more sparse, and suggest there may be complicating factors when comparing between multi-proxy reconstructions.

  • Open Access English
    Authors: 
    Hassenrück, Christiane; Hofmann, Laurie C; Bischof, Kai; Ramette, Alban;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science

    Seagrass meadows are a crucial component of tropical marine reef ecosystems. The seagrass plants are colonized by a multitude of epiphytic organisms that contribute to determining the ecological role of seagrasses. To better understand how environmental changes like ocean acidification might affect epiphytic assemblages, the microbial community composition of the epiphytic biofilm of Enhalus acroides was investigated at a natural CO2 vent in Papua New Guinea using molecular fingerprinting and next generation sequencing of 16S and 18S rRNA genes. Both bacterial and eukaryotic epiphytes formed distinct communities at the CO2-impacted site compared to the control site. This site-related CO2 effect was also visible in the succession pattern of microbial epiphytes. We further found an increased abundance of bacterial types associated with coral diseases at the CO2-impacted site (Fusobacteria, Thalassomonas) whereas eukaryotes such as certain crustose coralline algae commonly related to healthy reefs were less diverse. These trends in the epiphytic community of E. acroides suggest a potential role of seagrasses as vectors of coral pathogens and may support previous predictions of a decrease in reef health and prevalence of diseases under future ocean acidification scenarios.

  • Open Access English
    Authors: 
    Pop Ristova, Petra; Wenzhöfer, Frank; Ramette, Alban; Zabel, Matthias; Fischer, David; Kasten, Sabine; Boetius, Antje;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science

    The giant pockmark REGAB (West African margin, 3160 m water depth) is an active methane-emitting cold seep ecosystem, where the energy derived from microbially mediated oxidation of methane supports high biomass and diversity of chemosynthetic communities. Bare sediments interspersed with heterogeneous chemosynthetic assemblages of mytilid mussels, vesicomyid clams and siboglinid tubeworms form a complex seep ecosystem. To better understand if benthic bacterial communities reflect the patchy distribution of chemosynthetic fauna, all major chemosynthetic habitats at REGAB were investigated using an interdisciplinary approach combining porewater geochemistry, in situ quantification of fluxes and consumption of methane, as well bacterial community fingerprinting. This study revealed that sediments populated by different fauna assemblages show distinct biogeochemical activities and are associated with distinct sediment bacterial communities. The methane consumption and methane effluxes ranged over one to two orders of magnitude across habitats, and reached highest values at the mussel habitat, which hosted a different bacterial community compared to the other habitats. Clam assemblages had a profound impact on the sediment geochemistry, but less so on the bacterial community structure. Moreover, all clam assemblages at REGAB were restricted to sediments characterized by complete methane consumption in the seafloor, and intermediate biogeochemical activity. Overall, variations in the sediment geochemistry were reflected in the distribution of both fauna and microbial communities; and were mostly determined by methane flux.

  • Open Access English
    Authors: 
    Rampen, Sebastiaan W; Willmott, Verónica; Kim, Jung-Hyun; Rodrigo-Gámiz, Marta; Uliana, Eleonora; Mollenhauer, Gesine; Schefuß, Enno; Sinninghe Damsté, Jaap S; Schouten, Stefan;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
    Project: EC | PACEMAKER (226600)

    Long chain alkyl diols form a group of lipids occurring widely in marine environments. Recent studies have suggested several palaeoclimatological applications for proxies based on their distributions, but also revealed uncertainties about their applicability. Here we evaluate the use of long chain 1,14-alkyl diol indices for reconstruction of temperature and upwelling conditions by comparing index values, obtained from a comprehensive set of marine surface sediments, with environmental factors like sea surface temperature (SST), salinity and nutrient concentrations. Previous cultivation efforts indicated a strong effect of temperature on the degree of saturation and the chain length distribution of long chain 1,14-alkyl diols in Proboscia spp., quantified in the diol saturation index (DSI) and diol chain length index (DCI), respectively. However, values of these indices in surface sediments show no relationship with annual mean SST of the overlying water. It remains unknown what determines the DSI, although our data suggests that it may be affected by diagenesis, while the relationship between temperature and DCI may be different for different Proboscia species. In addition, contributions of algae other than Proboscia diatoms may affect both indices, although our data provide no direct evidence for additional long chain 1,14-alkyl diol sources. Two other indices using the abundance of 1,14-diols vs. 1,13-diols and C30 1,15-diols have previously been applied as indicators for upwelling intensity at different locations. The geographical distribution of their values supports the use of 1,14 diols vs. 1,13 diols [C28 + C30 1,14-diols]/[(C28 + C30 1,13-diols) + (C28 + C30 1,14-diols)] as a general indicator for high nutrient or upwelling conditions.

search
Include:
The following results are related to European Marine Science. Are you interested to view more results? Visit OpenAIRE - Explore.
1,192 Research products, page 1 of 120
  • Open Access English
    Authors: 
    Huse, Geir;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
    Project: EC | EURO-BASIN (264933)

    Acoustic estimates of herring and blue whiting abundance were obtained during the surveys using the Simrad ER60 scientific echosounder. The allocation of NASC-values to herring, blue whiting and other acoustic targets were based on the composition of the trawl catches and the appearance of echo recordings. To estimate the abundance, the allocated NASC -values were averaged for ICES-squares (0.5° latitude by 1° longitude). For each statistical square, the unit area density of fish (rA) in number per square nautical mile (N*nm-2) was calculated using standard equations (Foote et al., 1987; Toresen et al., 1998). To estimate the total abundance of fish, the unit area abundance for each statistical square was multiplied by the number of square nautical miles in each statistical square and then summed for all the statistical squares within defined subareas and over the total area. Biomass estimation was calculated by multiplying abundance in numbers by the average weight of the fish in each statistical square then summing all squares within defined subareas and over the total area. The Norwegian BEAM soft-ware (Totland and Godø 2001) was used to make estimates of total biomass.

  • Open Access English
    Authors: 
    Dziadek, Ricarda;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science

    This dataset compiles in-situ temperature measurements for geothermal heat flow estimates and water temperature profiles of the water column, extracted from Miniaturized Temperature data-Logger (MTL). The data were collected during RV POLARSTERN cruise PS104 in 2017 in Amundsen Sea.

  • Open Access English
    Authors: 
    Waska, Hannelore; Brumsack, Hans-Jürgen; Massmann, Gudrun; Koschinsky, Andrea; Schnetger, Bernhard; Simon, Heike; Dittmar, Thorsten;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science

    Data from pore water (subterranean estuary) and seawater from Spiekeroog south (near ICBM time series station and campsite, 53°45'13.5"N 7°40'22.5"E) and west beach ("Sturmeck", 53°46'10.0"N 7°40'26.2"E). South beach data were collected in August 2012, and west beach data were collected in November 2012. Sample abbreviations: SB=South Beach, WB=West Beach. DUNE=most landward station near dunes, MIX=mid-way station between dune base and low water line, LTWL=low tide water line. Pore water (DUNE, MIX, LTWL) sample collection was conducted at different sediment depths (50, 100, 150 cm below sediment surface). Stainless steel push-point lancets were insetred into the sediment, and pore water was withdrawn via vacuum (hand pumps) into nalgene polycarbonate bottles. Filtration was done using inline PES cartridge filters. The vacuum bottles were argon gas-flushed to avoid oxygen contamination. Sea water (SW) was collected with polycarbonate bottles and from LDPE seepage meter bags (SP) and filtered upon return to the laboratory (same day, PES filter cartridges). Sample collection was trace organic and metal clean (soaking and rinsing of bottles, tubing, and filters with diluted HNO3 and HCl suprapur), with sample materials consisting of polyethylene, polypropylene, and polycarbonate. Solid-phase extraction was done with BOND Elut PPL cartridges and elution with Methanol Optima grade. Measurements were done with VA Computrace 757 (Cu ligand concentrations and stability constants), HR-ICP-MS (Cu, Fe, and Mn concentrations), FT-ICR-MS (DOM), spectrophotometry (nutrients), and TOC analyzer (DOC and TDN). Trace metal concentrations (Fe, Cu, Mn) and speciation (oxidation state, size fractions, and organic association), as well as nitrogen species and concentrations: "Spiekeroog beach subterranean estuary environmental data". Concentrations (µM or nM) are denoted in the headers. CuL1=Cu-binding ligands concentrations (nM), logK1=Cu-binding ligand stability constant. Molecular composition of dissolved organic matter and associated Fe and Cu: "Spiekeroog beach STE_ESI_x_Crosstab_x". pos & neg = positive and negative ionization mode. BSA & NWA = basic/strong acidic and neutral/weak acidic, refer to the extracted DOM fraction. Processed figures and tables based on the original data are published here: https://doi.org/10.1016/j.gca.2019.06.004

  • Open Access English
    Authors: 
    Tessin, Allyson; März, Christian; Kędra, Monika; Matthiessen, Jens; Morata, Nathalie; Nairn, Michael; O'Regan, Matthew; Peeken, Ilka;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
    Project: EC | PaNDA (709175)

    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.

  • Open Access English
    Authors: 
    Robinson, Tiera-Brandy; Stolle, Christian; Wurl, Oliver;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science

    Biochemical data from 3 different regions; Cape Verde, the Baltic Sea, and Norwegian fjords/Sea. discreet samples for TEP, Chl a, POC, PON and nutrients as well as 2 and 24 hour average data on sea state parameters; temperature, salinity, PAR and wind speed. Vertical profile data for TEP, POC, TCN, small autotrophs and Chl a are also presented for depths of 0-2m, sampled in the Baltic and Norwegian Seas.

  • 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: 
    Barker, Stephen; Cacho, Isabel; Benway, Heather M; Tachikawa, Kazuyo;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science

    As part of the Multi-proxy Approach for the Reconstruction of the Glacial Ocean (MARGO) incentive, published and unpublished temperature reconstructions for the Last Glacial Maximum (LGM) based on planktonic foraminiferal Mg/Ca ratios have been synthesised and made available in an online database. Development and applications of Mg/Ca thermometry are described in order to illustrate the current state of the method. Various attempts to calibrate foraminiferal Mg/Ca ratios with temperature, including culture, trap and core-top approaches have given very consistent results although differences in methodological techniques can produce offsets between laboratories which need to be assessed and accounted for where possible. Dissolution of foraminiferal calcite at the sea-floor generally causes a lowering of Mg/Ca ratios. This effect requires further study in order to account and potentially correct for it if dissolution has occurred. Mg/Ca thermometry has advantages over other paleotemperature proxies including its use to investigate changes in the oxygen isotopic composition of seawater and the ability to reconstruct changes in the thermal structure of the water column by use of multiple species from different depth and or seasonal habitats. Presently available data are somewhat limited to low latitudes where they give fairly consistent values for the temperature difference between Late Holocene and the LGM (2-3.5 °C). Data from higher latitudes are more sparse, and suggest there may be complicating factors when comparing between multi-proxy reconstructions.

  • Open Access English
    Authors: 
    Hassenrück, Christiane; Hofmann, Laurie C; Bischof, Kai; Ramette, Alban;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science

    Seagrass meadows are a crucial component of tropical marine reef ecosystems. The seagrass plants are colonized by a multitude of epiphytic organisms that contribute to determining the ecological role of seagrasses. To better understand how environmental changes like ocean acidification might affect epiphytic assemblages, the microbial community composition of the epiphytic biofilm of Enhalus acroides was investigated at a natural CO2 vent in Papua New Guinea using molecular fingerprinting and next generation sequencing of 16S and 18S rRNA genes. Both bacterial and eukaryotic epiphytes formed distinct communities at the CO2-impacted site compared to the control site. This site-related CO2 effect was also visible in the succession pattern of microbial epiphytes. We further found an increased abundance of bacterial types associated with coral diseases at the CO2-impacted site (Fusobacteria, Thalassomonas) whereas eukaryotes such as certain crustose coralline algae commonly related to healthy reefs were less diverse. These trends in the epiphytic community of E. acroides suggest a potential role of seagrasses as vectors of coral pathogens and may support previous predictions of a decrease in reef health and prevalence of diseases under future ocean acidification scenarios.

  • Open Access English
    Authors: 
    Pop Ristova, Petra; Wenzhöfer, Frank; Ramette, Alban; Zabel, Matthias; Fischer, David; Kasten, Sabine; Boetius, Antje;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science

    The giant pockmark REGAB (West African margin, 3160 m water depth) is an active methane-emitting cold seep ecosystem, where the energy derived from microbially mediated oxidation of methane supports high biomass and diversity of chemosynthetic communities. Bare sediments interspersed with heterogeneous chemosynthetic assemblages of mytilid mussels, vesicomyid clams and siboglinid tubeworms form a complex seep ecosystem. To better understand if benthic bacterial communities reflect the patchy distribution of chemosynthetic fauna, all major chemosynthetic habitats at REGAB were investigated using an interdisciplinary approach combining porewater geochemistry, in situ quantification of fluxes and consumption of methane, as well bacterial community fingerprinting. This study revealed that sediments populated by different fauna assemblages show distinct biogeochemical activities and are associated with distinct sediment bacterial communities. The methane consumption and methane effluxes ranged over one to two orders of magnitude across habitats, and reached highest values at the mussel habitat, which hosted a different bacterial community compared to the other habitats. Clam assemblages had a profound impact on the sediment geochemistry, but less so on the bacterial community structure. Moreover, all clam assemblages at REGAB were restricted to sediments characterized by complete methane consumption in the seafloor, and intermediate biogeochemical activity. Overall, variations in the sediment geochemistry were reflected in the distribution of both fauna and microbial communities; and were mostly determined by methane flux.

  • Open Access English
    Authors: 
    Rampen, Sebastiaan W; Willmott, Verónica; Kim, Jung-Hyun; Rodrigo-Gámiz, Marta; Uliana, Eleonora; Mollenhauer, Gesine; Schefuß, Enno; Sinninghe Damsté, Jaap S; Schouten, Stefan;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
    Project: EC | PACEMAKER (226600)

    Long chain alkyl diols form a group of lipids occurring widely in marine environments. Recent studies have suggested several palaeoclimatological applications for proxies based on their distributions, but also revealed uncertainties about their applicability. Here we evaluate the use of long chain 1,14-alkyl diol indices for reconstruction of temperature and upwelling conditions by comparing index values, obtained from a comprehensive set of marine surface sediments, with environmental factors like sea surface temperature (SST), salinity and nutrient concentrations. Previous cultivation efforts indicated a strong effect of temperature on the degree of saturation and the chain length distribution of long chain 1,14-alkyl diols in Proboscia spp., quantified in the diol saturation index (DSI) and diol chain length index (DCI), respectively. However, values of these indices in surface sediments show no relationship with annual mean SST of the overlying water. It remains unknown what determines the DSI, although our data suggests that it may be affected by diagenesis, while the relationship between temperature and DCI may be different for different Proboscia species. In addition, contributions of algae other than Proboscia diatoms may affect both indices, although our data provide no direct evidence for additional long chain 1,14-alkyl diol sources. Two other indices using the abundance of 1,14-diols vs. 1,13-diols and C30 1,15-diols have previously been applied as indicators for upwelling intensity at different locations. The geographical distribution of their values supports the use of 1,14 diols vs. 1,13 diols [C28 + C30 1,14-diols]/[(C28 + C30 1,13-diols) + (C28 + C30 1,14-diols)] as a general indicator for high nutrient or upwelling conditions.