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  • 1
    Call number: AWI G2-18-91716
    Type of Medium: Monograph available for loan
    Pages: 134 S , Ill., graph. darst , 24 cm
    Language: English
    Note: CONTENTS: 1. Introduction. - 1.1. Research at the NEA dumpsite: CRESP and the DORA project. - 1.2. Acknowledgments. - 1.3. Source term: the radionuclides of interest. - 2. Material and methods. - 2.1. Cruises to the dumpsite. - 2.2. Sampling scheme. - 3. Geochemistry. - 3.1. Introduction. - 3.2. Methods. - 3.3. Recent sedimentological history. - 3.4. Elemental and mineralogical composition of the sediment. - 3.4.1. Mineralogical composition. - 3.4.2. Major elements. - 3.4.3. Trace elements. - 3.5. Early diagenetic reactions in the sediment. - 3.5.1. Mineralization of organic matter. - 3.5.1.1. Sequence of electron acceptors and changes in redox conditions. - 3.5.1.2. Oxygen reduction. - 3.5.1.3. Nitrate, manganese and iron reduction. - 3.5.1.4. Sulfate reduction. - 3.5.2. Cation exchange. - 3.5.3. Dissolution of carbonates. - 3.6. Trace element diagenesis. - 3.6.1. Trace metals. - 3.6.2. Mn, Fe, Co. - 3.6.3. Cu, Ni, Cd, Zn. - 3.6.4. Rare earth elements. - 3.6.5. Trace element mobility; the concept of distribution coefficients. - 3.7. Diagenetic modeling. - 3.8. Measurements in the nepheloid layer. - 3.9. Conclusions on the behaviour of each of the radionuclides of major concern. - 4. Biology. - 4.1. Introduction. - 4.2. Methods. - 4.2.1. Meiofauna. - 4.2.2. Macrofauna and large meiofauna. - 4.2.3. Megafauna. - 4.2.4. Diversity of Nematoda. - 4.2.5. Trophic structure of Nematoda. - 4.3. Results and discussion. - 4.3.1. Meiofauna. - 4.3.1.1. Density. - 4.3.1.2. Biomass. - 4.3.1.3. Horizontal distribution. - 4.3.1.4. Vertical distribution. - 4.3.1.5. Composition and trophic structure of the Nematoda fauna. - 4.3.1.6. Diversity of Nematoda. - 4.3.2. Macrofauna. - 4.3.3. Large meiofauna. - 4.3.4. Comparison of meio- and macrofauna. - 4.3.5. Megafauna. - 4.3.6. Chemical analyses of bottom fishes. - 4.4. Foodweb. - 4.5. Primary production. - 4.6. Conclusions. - 5. Bioturbation. - 6. Summary and conclusions regarding the fate of radionuclides released at the seafloor. - 7. References.
    Location: AWI Reading room
    Branch Library: AWI Library
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  • 2
    ISSN: 1573-5117
    Keywords: trawlfauna ; Mauritanian shelf
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In May 1988, epifaunal trawlsamples were collected at 17 stations on the Mauritanian shelf off the Banc d'Arguin. The species composition and biomass of the invertebrates and demersal fish were analysed. On the basis of species abundances, three station groups could be distinguished each corresponding to a subregion of the shelf: an inner shelf, a midshelf and an outer shelf station group. The average depth increased from 20 m for the inner to more than 100 m for the outer shelf stations. The biomass of mobile epifauna and fish was lowest on the inner shelf stations where the trawlfauna was dominated by large sessile filterfeeders. The trawlfaunas of the mid- and outer shelf were more similar in species composition. Demersal fish and crustaceans appeared to be more abundant on the outer shelf. The increase in density and biomass from inner to outer shelf is discussed in relation to the distribution of the infauna and the hydrographical conditions on the Mauritanian shelf. Being a demersal fishing area, density and biomass of the epifauna on the shelf are compared with that of the demersal fishing grounds in the southern North Sea. The result of this comparison shows that, except for echinoderms, all taxa attain higher densities and biomasses at the Mauritanian shelf.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2015-07-29
    Description: This study characterizes the microbial community composition over Haas Mound, one of the most prominent cold-water coral mounds of the Logachev Mound province (Rockall Bank, NE Atlantic). We outline patterns of distribution vertically – from the seafloor to the water column – and laterally – across the mound – and couple these to mound topography and hydrography. Samples of water, sediment and Lophelia pertusa were collected in 2012 and 2013 from locations that were chosen based on high definition video surveys. Temperature and current measurements were obtained at two sites at the summit and foot of Haas Mound to study near-bed hydrodynamic conditions. Overlaying water was collected from depths of 400 m as well as 5 and 10 m above the bottom using a CTD/Rosette system. Near-bottom water, sediment and L. pertusa mucus and skeleton samples were obtained with a box corer. Of all these biotopes, Roche GS-FLX amplicon sequencing targeting both Bacteria and Archaea was carried out, augmenting our understanding of deep sea microbial consortia. The pattern of similarities between samples, visualized by multi-dimensional scaling (MDS), indicates a strong link between the distribution of microbes and the specific biotopes. The microbial operational taxonomic unit (OTU) diversity was the highest in near-bottom water, which was sampled in the coral framework. For the first time, Thaumarchaeota marine group I (MGI) were found in L. pertusa mucus; Endozoicomonas was detected in skeleton, mucus and near-bottom water, whereas Mycoplasma was only detected in skeleton and near-bottom water, however not in mucus. Analysis of similarities (ANOSIM) indicates that overlaying water is well-mixed at 400 m depth but less so at 5 and 10 m above the bottom, where the composition of microbial communities differed significantly between summit, slope and off-mound. At all locations, the near-bottom water differed significantly from water at 5 m above the bottom, illustrating that the near-bottom water in between the coral framework represents a separate microbial habitat. Furthermore, the observed spatial heterogeneity in microbial communities is discussed in relation to environmental conditions.
    Print ISSN: 1726-4170
    Electronic ISSN: 1726-4189
    Topics: Biology , Geosciences
    Published by Copernicus on behalf of European Geosciences Union (EGU).
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  • 4
  • 5
    Publication Date: 2015-01-22
    Description: This study shows the microbial community composition over Haas Mound, one of the most prominent cold-water coral mounds of the Logachev Mound Province (Rockall Bank, NE Atlantic), outlining distribution patterns both vertically from the seafloor to the water column and laterally across the mound and coupling this to mound topography and hydrography. Samples were collected in 2012 and 2013 from biotopes that were partially chosen based on high definition video surveys that were conducted prior to sampling and included overlaying water (400 m depth and 5+10 m above the bottom (m ab)) collected with a CTD/Rosette system and near-bottom water, sediment, Lophelia pertusa mucus, and L. pertusa skeleton samples collected with a box-core. Furthermore, temperature and current measurements were obtained at two sites at the summit and foot of Haas Mound to study near-bed hydrodynamic conditions. Community composition was determined by next generation Roche 454 sequencing yielding high-resolution records of 16 S rRNA genotypes, improving our understanding of deep-sea microbial consortia. With the methods we employed we were able to report for the first time Archaea in association with L. pertusa. The pattern of similarities between samples visualized by multi-dimensional scaling (MDS), indicates a strong link between the distribution of microbes and specific biotopes. All biotopes share a number of taxa, but biotopes are distinct on basis of relative abundances and a small number of unique taxa. Similarity in microbes indicates that water is well-mixed at 400 m depth, but less so at 5 + 10 m above the bottom, where microbial communities differed between summit, slope and off mound. Even more variability was observed in the near-bottom water samples, which group according to sampling station. Likely the coral framework prevents the near-bottom water in between the branches to be vigorously mixed with the water overlaying the reef. The microbial consortium on Haas Mound appears strongly linked with the surrounding environment, making cold-water coral communities sensitive to outside environmental influences.
    Print ISSN: 1810-6277
    Electronic ISSN: 1810-6285
    Topics: Biology , Geosciences
    Published by Copernicus on behalf of European Geosciences Union (EGU).
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