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  • Other Sources  (468)
  • Elsevier  (257)
  • Springer  (156)
  • Wiley  (55)
  • 2005-2009  (468)
  • 1950-1954
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  • 1940-1944
  • 2007  (215)
  • 2005  (253)
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  • 2005-2009  (468)
  • 1950-1954
  • 1945-1949
  • 1940-1944
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  • 1
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    Fractal Behaviour of the Earth System (2005)
    Springer
    In:  Norwell, Springer, vol. 6, no. 3, pp. 2-203, (ISBN: 3-540-26532-5, XVI + 208 p. 72 illus.)
    Details
    Publication Date: 2005
    Keywords: FractureT ; Seismology ; Geoelectrics ; Electromagnetic methods/phenomena ; Geothermics ; Non-linear effects ; Dynamic ; Earth ; system ; geophysics ; Inhomogeneity ; scaling
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    BIBLIOGRAPHY SEISMOLOGY
  • 2
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    Relating fault mechanics to fault zone structure (2005)
    Elsevier
    In:  Advances in Geophysics, ed.: Renata Dmowska, Warszawa, Elsevier, vol. 47, no. 7, pp. 65-111, pp. L21303, (ISBN: 0-12-018847-3)
    Details
    Publication Date: 2005
    Keywords: Fault zone ; Rock mechanics ; Friction ; Fracture ; Physical properties of rocks ; geometry
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    BIBLIOGRAPHY SEISMOLOGY
  • 3
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    Crustal deformation in the southcentral Alaska subduction zone (2005)
    Elsevier
    In:  Advances in Geophysics, ed.: Renata Dmowska, Heidelberg, Elsevier, vol. 47, no. 8, pp. 1-64, pp. 1516, (ISBN: 0-12-018847-3)
    Details
    Publication Date: 2005
    Keywords: Crustal deformation (cf. Earthquake precursor: deformation or strain) ; Subduction zone ; USA
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    BIBLIOGRAPHY SEISMOLOGY
  • 4
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    Developing Tsunami-Resilient Communities (2005)
    Springer
    In:  Amsterdam, Springer, vol. 1, pp. 225, (1-4020-3353-2)
    Details
    Publication Date: 2005
    Keywords: Tsunami(s) ; Earthquake risk ; Earthquake precursor: prediction research ; Review article ; Early warning systems (earthquakes, volcanic eruptions, tsunamis etc.) ; Modelling ; NATHAZ ; measurement, ; tsunami ; model, ; data ; assimilation, ; data ; inversion, ; tsunami ; warning, ; tsunameters, ; forecast, ; hazard ; mitigation
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  • 5
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    Physical Geodesy (2005)
    Springer
    In:  New York, 390 pp., Springer, vol. 36, no. XVI:, pp. 1-14, (ISBN 3-211-23584-1)
    Details
    Publication Date: 2005
    Description: Motivation, Fundamentals of potential theory The gravity field of the earth, Gravity reduction, Heights The geometry of the earth, Gravity field outside the earth, Space methods Modern views on the determination of the figure of the earth Statistical methods in physical geodesy, Least-squares collocation Computational methods, References, Subject index
    Keywords: Textbook of geodesy ; Global Positioning System ; Geoid ; Gravimetry ; Potential ; Theory ; Reference ; Systems ; collocation ; geodetic ; satellite ; techniques ; heights
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    BIBLIOGRAPHY SEISMOLOGY
  • 6
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    Geographic Information System and Science (2005)
    Wiley
    In:  Chichester, 2nd ed., xvii + 517 pp., Wiley, vol. 5, no. 22, pp. 662-664, (ISBN 0-470-87000-1 (HB), ISBN 0-470-87001-X (PB))
    Details
    Publication Date: 2005
    Keywords: GIS ; Textbook of informatics ; Textbook of geography ; geography ; management ; policy
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  • 7
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    Geo-Information for Disaster Management (2005)
    Springer
    In:  Berlin, Heidelberg, New York, Springer, vol. 4, no. 85, pp. 175, (ISBN 3-540-24988-5)
    Details
    Publication Date: 2005
    Keywords: Textbook of informatics ; Earthquake hazard ; Earthquake risk ; Tsunami(s) ; Proceedings of a conference ; INSPIRE ; OpenGIS ; GIS ; floods ; landslides ; storms ; geography ; Delft ; GFZ ; M ; 06.0234 ; 000303921
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  • 8
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    Tsunamis - Case Studies and Recent Developments (2005)
    Springer
    In:  Basel, Switzerland, Springer, vol. 20, no. Publ. No. 12, pp. 23-40, (ISBN 1-4020-3326-5, VIII + 343 pp.)
    Details
    Publication Date: 2005
    Description: Twenty papers comprise a timely review of state-of-the-art tsunami research. Various approaches are taken to study tsunamis: field-surveys of recent tsunamis; analysis of tide-gauge records; numerical simulations of tsunami generation and propagation, tank experiments, and geological studies of tsunami deposits.
    Keywords: GFZ ; M ; 06.0379 ; 000304412
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  • 9
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    A combined geophysical/engineering approach for the seismic safety of long-span bridges (2005)
    Springer
    In:  Professional Paper, Perspectives in Modern Seismology, Berlin, Springer, vol. 105, 223 pp., no. 231, pp. 13-30, (ISBN: 3-540-23712-7)
    Details
    Publication Date: 2005
    Keywords: Earthquake risk ; Site amplification ; Strong motions ; Earthquake engineering, engineering seismology ; Synthetic seismograms ; NOISE ; Nakamura ; Modelling ; Cologne ; DFNK ; Faecke ; Facke
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  • 10
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    Acoustic and Elastic Wave Fields in Geophysics, III (2005)
    Elsevier
    In:  Amsterdam, 652 pp., Elsevier, vol. 39, no. XVI:, pp. 227-235, (0-444-51955-6)
    Details
    Publication Date: 2005
    Keywords: Seismics (controlled source seismology) ; Applied geophysics ; Wave propagation ; plane ; spherical ; and ; cylindrical ; Waves ; in ; isotropic ; and ; transversely ; isotropic ; solids, ; liquid-solid ; models, ; and ; media ; with ; cylindrical ; inclusions ; (boreholes) ; Textbook of geophysics
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  • 11
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    The 26 December 2004 Sumatra earthquake and tsunami seen by satellite altimetry and Global Positioning System (2005)
    Springer
    In:  Geo-Information for Disaster Management, Berlin, Heidelberg, New York, Springer, vol. 12, pp. 323-336, (ISBN 3-540-24988-5)
    Details
    Publication Date: 2005
    Keywords: Textbook of informatics ; Earthquake hazard ; Earthquake risk ; Tsunami(s) ; Proceedings of a conference ; Earthquake ; Indonesia ; Geodesy
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    BIBLIOGRAPHY SEISMOLOGY
  • 12
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    The Dead Sea fault and its effect on civilization (2005)
    Springer
    In:  Professional Paper, Perspectives in Modern Seismology, Dordrecht, Springer, vol. 65, no. 16, pp. 145-168, (ISBN 0080419208)
    Details
    Publication Date: 2005
    Keywords: paleo ; Seismicity ; Fault zone ; DSTF ; Seismology ; Early warning systems (earthquakes, volcanic eruptions, tsunamis etc.) ; Bucharest ; Romania ; Earthquake risk
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  • 13
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    Velocity field of the Aegean-Anatolian region from 3D finite element models (2005)
    Springer
    In:  Bull., Polar Proj. OP-O3A4, Perspectives in Modern Seismology, London, Springer, vol. 201, no. XVI:, pp. 169-184, (ISBN: 3-540-23712-7)
    Details
    Publication Date: 2005
    Keywords: Crustal deformation (cf. Earthquake precursor: deformation or strain) ; Geodesy ; Finite Element Method ; Modelling ; Three dimensional ; Seismology ; Early warning systems (earthquakes, volcanic eruptions, tsunamis etc.) ; Bucharest ; Romania ; Earthquake risk
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  • 14
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    Nonlinear seismology - the seismology of the XXI century (2005)
    Springer
    In:  Bull., Polar Proj. OP-O3A4, Perspectives in Modern Seismology, Dordrecht, Springer, vol. 20, no. 4, pp. 47-65, (ISBN 0080419208)
    Details
    Publication Date: 2005
    Keywords: Non-linear effects ; Seismology ; Early warning systems (earthquakes, volcanic eruptions, tsunamis etc.) ; Bucharest ; Romania ; Earthquake risk
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  • 15
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    Small-scale mantle plumes: Imaging and geodynamic aspects (2005)
    Springer
    In:  Bull., Open-File Rept., Perspectives in Modern Seismology, Arnsberg-Neheim, Springer, vol. 10, no. 87-17, pp. 69-94, (ISBN 0080419208)
    Details
    Publication Date: 2005
    Keywords: Plate tectonics ; hot ; spots ; GeodesyY ; Tomography ; Seismology ; Early warning systems (earthquakes, volcanic eruptions, tsunamis etc.) ; Bucharest ; Romania
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  • 16
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    An earthquake early warning system for the Romanian capital (2005)
    Springer
    In:  Professional Paper, Open-File Rept., Perspectives in Modern Seismology, Berlin, Springer, vol. 1, no. 16, pp. 1-12, (ISBN 0080419208)
    Details
    Publication Date: 2005
    Keywords: Review article ; Seismology ; Early warning systems (earthquakes, volcanic eruptions, tsunamis etc.) ; Bucharest ; Romania ; Earthquake risk
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  • 17
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    Deep water bottom current deposition in the northern South China Sea (2007)
    Springer
    In:  Science in China Series D: Earth Sciences, 50 (7). pp. 1060-1066.
    Details
    Publication Date: 2017-07-21
    Description: There are some active bottom currents on the northern continental slope of the South China Sea (SCS). Reflection seismic profiles show that the bottom current channels occur in the water depth range of 1000 to 2700 m, extending from the NE to the SW, leading to accumulation of discontinuous drifts with higher sedimentation rates on the eastern side of the channel. The stacking pattern of the layers suggests that these drifts propagated southwestward, following the direction of the bottom currents. One sedimentary drift to the southeast of the Dongsha Islands has the highest sedimentation rate of 97cm/ka in the last 12 ka. The sedimentary characteristics of the sediment layers indicate that these bottom currents are most likley caused by the water movement of a branch of the West Pacific Ocean Current, which enters the northern SCS via the Bashi Strait. Once formed, the bottom currents transport sediments along the northern slope of SCS southwestward and finally disappear into the central basin of the SCS. Due to the bottom current activity, the deep-sea sedimentary process in the northern SCS is complex.
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  • 18
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    Quantitation of DNA and RNA with Absorption and Fluorescence Spectroscopy (2007)
    Wiley
    In:  Current Protocols in Human Genetics, 53 (Suppl. 3D). A.3D.1-A.3D.21.
    Details
    Publication Date: 2018-01-16
    Description: Quantitation of nucleic acids is a fundamental tool in molecular biology that requires accuracy, reliability, and the use of increasingly smaller sample volumes. This unit describes the traditional absorbance measurement at 260 nm and three more sensitive fluorescence techniques, as well as three microvolume methods that use fiber optic technology in specialized cells or instrumentation. These procedures allow quantitation of DNA solutions ranging from 1 pg/µl to 50 mg/ml.
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  • 19
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    Surface carbohydrate composition of a tapeworm in its consecutive intermediate hosts: Individual variation and fitness consequences (2005)
    Elsevier
    In:  International Journal for Parasitology, 35 (14). pp. 1499-1507.
    Details
    Publication Date: 2020-07-28
    Description: Carbohydrates on parasite surfaces have been shown to play an important role in host–parasite coevolution, mediating host non-self recognition and parasite camouflage. Parasites that switch hosts can change their surface molecules to remain undetected by the diverse immune systems of their different hosts. However, the question of individual variation in surface sugar composition and its relation to infectivity, virulence, immune evasion and growth of a parasite in its different hosts is as yet largely unexplored. We studied such fitness consequences of variation in surface sugars in a sympatric host–parasite system consisting of the cestode Schistocephalus solidus and its intermediate hosts, a copepod and the three-spined stickleback. Using lectins to analyse the sugar composition, we show that the tapeworm changes its surface according to the invertebrate or vertebrate host. Importantly, sugar composition seems to be genetically variable, as shown by differences among tapeworm sibships. These differences are related to variation in parasite fitness in its second intermediate host, i.e. infectivity and growth. Surface sugar composition may thus be a proximate correlate of the evolutionarily relevant variability in infectivity and virulence of parasites in different hosts.
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  • 20
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    Shear band emergence in granular materials—a numerical study (2007)
    Wiley
    In:  International Journal for Numerical and Analytical Methods in Geomechanics, 31 (3). pp. 373-393.
    Details
    Publication Date: 2018-04-24
    Description: In contrast to continuum systems where localization or shear banding arises through a bifurcation in a predefined system of differential equations, shear bands emerge in numerical simulations of deforming granular systems with no prescribed mathematical relations other than simple contact forces between particles. Shear bands emerge from the self‐organization of large numbers of particles with long‐range geometrical interactions playing a dominant role; both translation and rotation of particles are important. Granular media therefore deform more like materials with non‐local constitutive relations than materials where only first‐order interactions are relevant. In this paper we adopt a thermo‐mechanical approach and explore the fluxes of energy in the evolving granular system (that has cohesion as well as friction between the particles) as it is loaded through the unstable localization regime, and track the evolution of energy dissipation. As in continua, the sign of the second‐order work defines the emergence of instability in the system. Initially, these instabilities decay into stable configurations of particles but with continued loading, force chains collapse locally to generate geometrically necessary fractures. These zones then propagate to generate localization zones. When these fractures form a continuous network, the system is at the percolation thresh‐hold for broken bonds. However, long before this stage, the second‐order work fluctuates in bursts weakly correlated with bursts in kinetic energy as damage accumulates. This behaviour suggests that any continuum constitutive description of granular media must be (i) non‐local in an anisotropic manner, (ii) micro‐polar, and (iii) involve damage evolution.
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  • 21
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    Morphology and environment of cold-water coral carbonate mounds on the NW European margin (2007)
    Springer
    In:  International Journal of Earth Sciences, 96 (1). pp. 37-56.
    Details
    Publication Date: 2017-06-27
    Description: Cold-water coral carbonate mounds, owing their presence mainly to the framework building coral Lophelia pertusa and the activity of associated organisms, are common along the European margin with their spatial distribution allowing them to be divided into a number of mound provinces. Variation in mound attributes are explored via a series of case studies on mound provinces that have been the most intensely investigated: Belgica, Hovland, Pelagia, Logachev and Norwegian Mounds. Morphological variation between mound provinces is discussed under the premise that mound morphology is an expression of the environmental conditions under which mounds are initiated and grow. Cold-water coral carbonate mounds can be divided into those exhibiting “inherited” morphologies (where mound morphology reflects the morphology of the colonised features) and “developed” morphology (where the mounds assume their own gross morphology mainly reflecting dominant hydrodynamic controls). Finer-scale, surface morphological features mainly reflecting biological growth forms are also discussed.
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  • 22
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    High occurrences of brominated lipid fatty acids in boreal sponges of the order Halichondrida (2007)
    Springer
    In:  Marine Biology, 150 (6). pp. 1153-1160.
    Details
    Publication Date: 2017-06-27
    Description: Sponges of warm- and temperate- but also cold-waters are known to synthesize structurally diverse primary and secondary metabolites. These compounds fulfill a variety of functions including adaptations of the cell membranes to environmental conditions. We show here that boreal sponges of the order Halichondrida are rich sources of brominated lipid fatty acids. The comparison of lipid compositions of halichondrid Demospongiae from boreal and warmer waters indicates an accumulation of brominated fatty acids in sponges from colder settings. Moreover, the spatial distribution of brominated fatty acids in the sponge tissue of one widely distributed sponge of the North-East Atlantic (Phakellia ventilabrum) hints to a function related to membrane fluidity and permeability rather than to defense against predation. However, brominated fatty acids are diagnostic for the presence of bromoperoxidases in sponges and may therefore be potentially useful as markers in a chemical screening for secondary metabolites of pharmacological interest.
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  • 23
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    Importance of geochemical transformations in determining submarine groundwater discharge-derived trace metal and nutrient fluxes (2007)
    Elsevier
    In:  Applied Geochemistry, 22 (2). pp. 477-490.
    Details
    Publication Date: 2018-03-09
    Description: Seasonal (Spring and Summer 2002) concentrations of dissolved (〈0.22 μm) trace metals (Ag, Al, Co, Cu, Mn, Ni, Pb), inorganic nutrients (NO3, PO4, Si), and DOC were determined in groundwater samples from 5 wells aligned along a 30 m shore-normal transect in West Neck Bay, Long Island, NY. Results show that significant, systematic changes in groundwater trace metal and nutrient composition occur along the flowpath from land to sea. While conservative mixing between West Neck Bay water and the groundwaters explains the behavior of Si and DOC, non-conservative inputs for Co and Ni were observed (concentration increases of 10- and 2-fold, respectively) and removal of PO4 and NO3 (decreases to about half) along the transport pathway. Groundwater-associated chemical fluxes from the aquifer to the embayment calculated for constituents not exhibiting conservative behavior can vary by orders of magnitude depending on sampling location and season (e.g. Co, 3.4 × 102– 8.2 × 103 μmol d−1). Using measured values from different wells as being representative of the true groundwater endmember chemical composition also results in calculation of very different fluxes (e.g., Cu, 6.3 × 103 μmol d−1 (inland, freshwater well) vs. 2.1 × 105 μmol d−1(seaward well, S = 17 ppt)). This study suggests that seasonal variability and chemical changes occurring within the subterranean estuary must be taken into account when determining the groundwater flux of dissolved trace metals and nutrients to the coastal ocean.
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  • 24
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    Radium mass-balance in Jamaica Bay, NY: Evidence for a substantial flux of submarine groundwater (2007)
    Elsevier
    In:  Marine Chemistry, 106 (3-4). pp. 419-441.
    Details
    Publication Date: 2018-03-09
    Description: A mass balance for the naturally-occurring radium isotopes (224Ra, 223Ra, 228Ra, and 226Ra) in Jamaica Bay, NY, was conducted by directly estimating the individual Ra contributions of wastewater discharge, diffusion from fine-grained subtidal sediments, water percolation through marshes, desorption from resuspended particles, and water exchange at the inlet. The mass balance revealed a major unknown source term accounting for 19–71% of the total Ra input, which could only be resolved by invoking a source from submarine groundwater. Shallow (〈 2 m depth) groundwater from permeable sediments in Jamaica Bay was brackish and enriched in Ra relative to surface bay waters by over two orders of magnitude. To balance Ra fluxes, a submarine groundwater input of 0.8 × 109–9.0 × 109 L d− 1 was required. This flux was similar for all four isotopes, with individual estimates varying by less than a factor of 2. Our calculated groundwater flux was 6- to 70-fold higher than the fresh groundwater discharge to the bay estimated by hydrological methods, but closely matched direct flow rates measured with seepage meters. This suggests that a substantial portion of the discharge consisted of recirculated seawater. The magnitude of submarine groundwater discharge varied seasonally, in the order: summer 〉 autumn 〉 spring. Chemical analyses suggest that the recirculated seawater component of submarine groundwater delivers as much dissolved nitrogen to the bay as the fresh groundwater flux.
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  • 25
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    The Toba supervolcanic eruption: Tephra-fall deposits in India and paleoanthropological implications (2007)
    Springer
    In:  In: The Evolution and History of Human Populations in South Asia. , ed. by Petraglia, M. D. and Allchin, B. Springer, Dordrecht, pp. 173-200.
    Details
    Publication Date: 2017-11-24
    Type: Book chapter , NonPeerReviewed
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  • 26
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    Paleomagnetic modeling of seamounts near the Hawaiian–Emperor bend (2005)
    Elsevier
    In:  Tectonophysics, 405 (1-4). pp. 121-140.
    Details
    Publication Date: 2019-04-29
    Description: The Hawaiian–Emperor Seamount chain records the motion of the Pacific Plate relative to the Hawaiian mantle hotspot for ~80 m.y. A notable feature of the chain is the pronounced bend at its middle. This bend had been widely credited to a change in plate motion, but recent research suggests a change in hotspot motion as an alternative. Existing paleomagnetic data from the Emperor Chain suggest that the hotspot moved south during the Late Cretaceous and Early Tertiary, but reached its current latitude by the age of the bend. Thus, data from area of the bend are important for understanding changes in plume latitude. In this study, we analyze the magnetic anomalies of five seamounts (Annei, Daikakuji-W, Daikakuji- E, Abbott, and Colahan) in the region of the bend. These particular seamounts were chosen because they have been recently surveyed to collect multibeam bathymetry and magnetic data positioned with GPS navigation. Inversions of the magnetic and bathymetric data were performed to determine the mean magnetization of each seamount and from these results, paleomagnetic poles and paleolatitudes were calculated. Three of the five seamounts have reversed magnetic polarities (two are normal) and four contain a small volume of magnetic polarity opposite to the main body, consistent with formation during the Early Cenozoic, a time of geomagnetic field reversals. Although magnetization inhomogene ties can degrade the accuracy of paleomagnetic poles calculated from such models, the seamounts give results consistent with one another and with other Pacific paleomagnetic data of approximately the same age. Seamount paleolatitudes range from 13.7 to 23.7, with an average of 19.4F7.4 (2j). These values are indistinguishable from the present-day paleolatitude of the Hawaiian hotspot. Together with other paleomagnetic and geologic evidence, these data imply that the Hawaiian hotspot has moved little in latitude during the past ~45 m.y.
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  • 27
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    Two new metabolites with cytotoxicities from deep-sea fungus, aspergillus sydowi YH11-2 (2007)
    Springer
    In:  Archives of Pharmacal Research, 30 (9). pp. 1051-1054.
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    Publication Date: 2020-06-12
    Description: Two new compounds, 2, 3, 5-trimethyl-6-(3-oxobutan-2-yl)-4H-pyran-4-one (1) and (2R)-2, 3-dihydro-7-hydroxy-6, 8-dimethyl-2-[(E)-prop-1-enyl] chromen-4-one (2), together with six known compounds (3–8), were isolated from a deep-sea fungus, identified as Aspergillus sydowi, by a bioassay-guided method. Their structures were elucidated by spectroscopic methods and the cytotoxicities were evaluated by SRB method.
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  • 28
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    Recent seismic activity (1994–2002) of the Santorini volcano using data from local seismological network (2005)
    Elsevier
    In:  Developments in Volcanology, 7 . pp. 185-203.
    Details
    Publication Date: 2020-07-30
    Description: The South Aegean Active Volcanic Arc consists of a chain of five volcanic centers, the most active of which is the Santorini Volcano. A local radio-linked seismological network is installed on the island consisting of five permanent and four temporary stations. The temporary stations have been in operation periodically during the period 1994–1996 and two of them were installed on adjacent islands. All stations are equipped with vertical-component short period seismometers. During the period 1994–2002 a significant number of earthquakes has been recorded, with local (duration) magnitudes, MD, up to 5.0 and focal depths varying between 0 km and 35 km. Two clusters of epicenters have been located in the broader area of the Santorini Volcano. The first cluster is located in the caldera of the volcano and is associated with the volcanic process in the Kameni Island. The second (larger) cluster is located near the northern edge of the Santorini Island at the Kolumbo Reef and is connected with the volcanic process at this reef. These clusters can be appropriately associated with the two main tectonic features (faults) in the area under study. The first one (N60°E direction) corresponds to the continuation of the Amorgos fault in the area, while the secondary tectonic line (EW direction) is probably related with the southern edge of a submarine graben, which is located between the islands Amorgos and Santorini. Using the data set of the best-located earthquakes, recorded during the period 1994–2002, an attempt has been made to derive an appropriate equivalent 1 –D earth model for the area under study, in order to improve the accuracy of the determined hypocenters, as well as to obtain a preliminary knowledge of the volcano structure.
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  • 29
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    Stromal biology of pancreatic cancer (2007)
    Wiley
    In:  Journal of Cellular Biochemistry, 101 (4). pp. 887-907.
    Details
    Publication Date: 2017-05-18
    Description: The genetic paradigm of cancer, focused largely on sequential molecular aberrations and associated biological impact in the neoplastic cell compartment of malignant tumors, has dominated our view of cancer pathogenesis. For the most part, this conceptualization has overlooked the dynamic and complex contributions of the surrounding microenvironment comprised of non-tumor cells (stroma) that may resist, react to, and/or foster tumor development. Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease in which a prominent tumor stroma compartment is a defining characteristic. Indeed, the bulk of PDAC tumor volume consists of non-neoplastic fibroblastic, vascular, and inflammatory cells surrounded by immense quantities of extracellular matrix, far exceeding that found in most other tumor types. Remarkably, little is known about the composition and physiology of the PDAC tumor microenvironment, in particular, the role of stroma in tumor initiation and progression. This review attempts to define key challenges, opportunities and state-of-knowledge relating to the PDAC microenvironment research with an emphasis on how inflammatory processes and key cancer pathways may shape the ontogeny of the tumor stroma. Such knowledge may be used to understand the evolution and biology of this lethal cancer and may convert these insights into new points of therapeutic intervention.
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  • 30
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    Biomarkers at the microscopic range: ToF-SIMS molecular imaging of Archaea-derived lipids in a microbial mat (2007)
    Wiley
    In:  Geobiology, 5 (4). pp. 413-421.
    Details
    Publication Date: 2017-06-27
    Description: Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) with a bismuth cluster primary ion source was used for analysing microbial lipid biomarkers in 10-µm-thick microscopic cryosections of methanotrophic microbial mats from the Black Sea. Without further sample preparation, archaeal isopranyl glycerol di- and tetraether core lipids, together with their intact diglycoside (gentiobiosyl-) derivatives, were simultaneously identified by exact mass determination. Utilizing the imaging capability of ToF-SIMS, the spatial distributions of these biomarkers were mapped at a lateral resolution of 〈 5 µm in 500 × 500 µm2 areas on the mat sections. Using inline image cluster projectiles in the burst alignment mode, it was possible to reach a lateral resolution of 1 µm on an area of 233 × 233 µm, thus approaching the typical size of microbial cells. The mappings showed different ‘provenances’ within the sections that are distinguished by individual lipid fingerprints, namely (A) the diethers archaeol and hydroxyarchaeol co-occurring with glycerol dialkyl glycerol tetraethers (GDGT), (B) hydroxyarchaeol and dihydroxyarchaeol, and (C) GDGT and gentiobiosyl-GDGT. Because ToF-SIMS is a virtually nondestructive technique affecting only the outermost layers of the sample surface (typically 10–100 nm), it was possible to further examine the studied areas using conventional microscopy, and associate the individual lipid patterns with specific morphological traits. This showed that provenance (B) was frequently associated with irregular, methane-derived CaCO3 crystallites, whereas provenance (C) revealed a population of fluorescent, filamentous microorganisms showing the morphology of known methanotrophic ANME-1 archaea. The direct coupling of imaging mass spectrometry with microscopic techniques reveals interesting perspectives for the in-situ study of lipids in geobiology, microbial ecology, and organic geochemistry. After further developing protocols for handling different kinds of environmental samples, ToF-SIMS could be used as a tool to attack many challenging problems in these fields, such as the attribution of biological source(s) to particular biomarkers in question, or the high-resolution tracking of biogeochemical processes in modern and ancient natural environments.
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  • 31
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    Methane-derived carbonate build-ups and associated microbial communities at cold seeps on the lower Crimean shelf (Black Sea) (2005)
    Springer
    In:  Facies, 51 (1-4). pp. 66-79.
    Details
    Publication Date: 2018-01-19
    Description: In the euxinic waters of the NW’ Black Sea shelf, tower-like carbonate build-ups up to several metres in height grow at sites of cold methane seepage. These structures are part of an unique microbial ecosystem that shows a considerable biodiversity and a remarkable degree of organization. The accretion of the build-ups is promoted by the growth of centimetre-sized, methane-filled spheres constructed by calcifying microbial mats. Progressive mineralization of these spheres involves the early precipitation of strongly luminescent high-Mg-calcite rich in iron sulphides, and closely interfingered aragonite phases that finally create the stable (mega-) thrombolithic fabric of the towers. Within the microbial mats, microorganisms occur in distinctive spatial arrangements. Major players among the microbial consortia are the archaea groups ANME-1 and ANME-2, Crenarchaeota, and sulphate-reducing bacteria (SRB) of the Desulfosarcina/Desulfobacterium group. The intracellular precipitation of iron sulphides (greigite) by some of these bacteria, growing in close association with ANME-2, suggests iron cycling as an additional biogeochemical pathway involved in the anaerobic oxidation of methane (AOM).
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  • 32
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    A Self-Consistent Bathymetric Mapping Algorithm (2007)
    Wiley
    In:  Journal of Field Robotics, 24 (1-2). pp. 23-50.
    Details
    Publication Date: 2017-08-10
    Description: The achievable accuracy of bathymetric mapping in the deep ocean using robotic systems is most often limited by the available guidance or navigation information used to combine the measured sonar ranges during the map making process. This paper presents an algorithm designed to mitigate the affects of poor ground referenced navigation by applying the principles of map registration and pose filtering commonly used in simultaneous localization and mapping (SLAM) algorithms. The goal of the algorithm is to produce a self-consistent point cloud representation of the bottom terrain with errors that are on a scale similar to the sonar range resolution rather than any direct positioning measurement. The presented algorithm operates causally and utilizes sensor data that are common to instrumented underwater robotic vehicles used for mapping and scientific explorations. Real world results are shown for data taken on several expeditions with the JASON remotely operated vehicle (ROV). Comparisons are made between more standard mapping approaches and the proposed method is shown to significantly improve the map quality and reveal scene information that would have otherwise been obscured due to poor direct navigation information.
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  • 33
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    Novel Sorbicillin Derivatives with an Unprecedented Carbon Skeleton from the Sponge-Derived FungusTrichoderma Species (2007)
    Wiley
    In:  European Journal of Organic Chemistry, 2007 (14). pp. 2268-2275.
    Details
    Publication Date: 2017-09-06
    Description: Chemical investigation of the fungus Trichoderma sp., isolated from the Caribbean sponge Agelas dispar led to four novel sorbicillinoid polyketide derivatives (1–4) with an unprecedented tricyclic ring system. The structures of all compounds, including the absolute configuration, were determined by interpretation of their spectroscopic data (1D and 2D NMR, CD, MS, UV and IR), and molecular modeling calculations.
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  • 34
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    Major and trace element composition of the depleted MORB mantle (DMM) (2005)
    Elsevier
    In:  Earth and Planetary Science Letters, 231 (1-2). pp. 53-72.
    Details
    Publication Date: 2017-05-02
    Description: We derive an estimate for the chemical composition of the depleted MORB mantle (DMM), the source reservoir to mid-ocean ridge basalts (MORBs), which represents at least 30% the mass of the whole silicate Earth. A database for the chemical and physical properties of abyssal peridotites has become robust and complete enough to truly access a reference DMM. Using trace element depletion trends from the abyssal peridotites, it is possible to construct a large part of DMM’s trace element pattern. Splicing this information with isotopic constraints (Sr–Nd–Pb–Hf) and canonical ratios (Ce/Pb, Nb/Ta, Nb/U, Ba/Rb, H2O/Ce, CO2/Nb and Cl/K), we can extend abundance estimates to all the incompatible elements including volatile content. The resulting trace element pattern for average DMM constrains parental MORB to be generated by 6% aggregated fractional melting, consistent with recent models for hydrous melting of the mantle [P.D. Asimow, J.E. Dixon, C.H. Langmuir, A hydrous melting and fractionation model for mid-ocean ridge basalts: application to the Mid-Atlantic Ridge near the Azores, Geochem. Geophys. Geosyst. 5 (2004) 10.1029/2003GC000568]. We show that DMM is roughly balanced by the continental crust and better balanced upon inclusion of ocean island basalt source and oceanic crust components. Compared to the primitive mantle, DMM has been depleted by 2–3% melt extraction and has only 15% the radiogenic heat production.
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  • 35
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    Calcifying extracellular mucus substances (EMS) of Madrepora oculata — a first geobiological approach (2005)
    Springer
    In:  In: Cold-Water Corals and Ecosystems. , ed. by Freiwald , A. and Roberts , J. M. Erlangen Earth Conference Series . Springer, Berlin, pp. 731-744. ISBN 978-3-540-24136-2
    Details
    Publication Date: 2017-07-07
    Description: Colonial non-zooxanthellate corals from deep-water coral reefs, Lophelia pertusa and Madrepora oculata, produce large amounts of extracellular mucus (EMS). This mucus has various functions, e.g., an antifouling capability protecting the coral skeleton from attacks of endolithic and boring organisms. Both corals show thick epithecal and exothecal skeletal parts with a clear lamellar growth pattern. The formation of the epitheca is unclear. It is supposed that the EMS play a central role during the calcification process of the epithecal skeletal parts. Staining with the fluorochrome tetracycline has shown an enrichment of Ca2+ ions in the mucus. In order to investigate this hypothesis, the protein content of the mucus and the intracrystalline organic matter from newly formed epithecal aragonite of Madrepora oculata was determined via sodium dodecyl sulfate (SDS) gel electrophoresis. Identical band patterns within both substances could be detected, one around 45 kDa molecular weight and a cluster around 30–35 kDa molecular weight. The occurrence of identical protein patterns within the mucus and in the newly formed aragonite confirms the idea that the mucus plays an important role during the organomineralization of the coral epitheca.
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  • 36
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    Role of cold-water Lophelia pertusa coral reefs as fish habitat in the NE Atlantic (2005)
    Springer
    In:  In: Cold-Water Corals and Ecosystems. , ed. by Freiwald, A. and Roberts, J. M. Erlangen Earth Conference Series . Springer, Berlin, pp. 771-805.
    Details
    Publication Date: 2017-07-07
    Description: The rate of discovery of reefs of the cold-water coral Lophelia pertusa (Linnaeus, 1758) has been remarkable, and attributable to the increased use of underwater video. These reefs form a major three-dimensional habitat in deeper waters where little other ‘cover’ for fish is available. They are common in the eastern North Atlantic, and occur at least in the western North Atlantic and off central Africa. There are also other non-reef records of Lophelia in the Atlantic, and in Indian and Pacific oceans. Thus, not only are these reefs a significant habitat on a local scale, but they may also provide an important habitat over a very wide geographic scale. The present study examined the association of fish species with Lophelia in the Northeast Atlantic, including the Trondheimsfjord and Sula Ridge in Norway, Kosterfjord in Sweden, Darwin Mounds west of Scotland, and Rockall Bank, Rockall Trough and Porcupine Seabight off Ireland. The fish fauna associated with a shipwreck west of Shetland was also studied. Data were collected from 11 study sites at 8 locations, using 52 hours of video and 15 reels of still photographs. Video and still photographs were collected from (1) manned submersible, (2) surface controlled remotely operated vehicle (ROV), (3) a towed “hopper” camera, (4) wide angle survey photography (WASP), (5) seabed high resolution imaging platform (SHRIMP), and (6) an in situ time-lapse camera “Bathysnap”. It was possible to identify 90 % of fish observed to species level and 6.5 % to genus or family level. Only 3.5 % of the fish were not identifiable. A guide to the fishes is given at http://www.ecoserve.ie/projects/aces/. Twenty-five species of fishes from 17 families were recorded over all the sites, of which 17 were of commercial importance and comprised 82 % of fish individuals observed. These commercial fish species contribute 90 % of commercial fish tonnage in the North Atlantic. The habitats sampled were comprised of 19 % reef, 20 % transitional zone (i.e. between living coral and debris zone), 25 % coral debris and 36 % off-reef seabed. Depth was the most significant parameter in influencing the fish associated with the reefs, both at the species and family level. There was a complete separation of sites above and below 400–600 m depth by multi-dimensional scaling (MDS) analysis. Less distinct assemblages of fish species were associated with each habitat. Fish species richness and abundance was greater on the reef than surrounding seabed. In fact, 92 % of species, and 80 % of individual fish were associated with the reef. The present data indicates that these reefs have a very important functional role in deep-water ecosystems as fish habitat.
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  • 37
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    Lipid geochemistry of methane-seep-related Black Sea carbonates (2005)
    Elsevier
    In:  Palaeogeography Palaeoclimatology Palaeoecology, 227 (1-3). pp. 31-47.
    Details
    Publication Date: 2017-06-30
    Description: Carbonates recovered from anoxic waters between 235 and 1555 m depth in the northwestern Black Sea were analyzed for lipid biomarkers and stable carbon isotopic compositions. In addition, a methane-seep-related microbial mat and a sample of surface sediment recovered from a non-seep site were studied for comparison. High concentrations of strongly 13C-depleted lipids attributed to bacteria and archaea mediating the anaerobic oxidation of methane (AOM) were found in all samples except for the sediment. Differences of the dominant AOM-performing communities between the carbonates indicated by specific lipid patterns appear to be caused by the respective biogeochemical settings. High proportions of ANME-2 consortia are found at sites of assumingly high partial pressures of methane while ANME-1 associations dominate at locations of moderate methane supply. In the sedimentary concretion, a complex mixture of biomarkers for terrestrial and planktonic organisms was found. Different molecular structures along with strong variations in the stable carbon isotopic compositions (δ13C = − 20.2‰ to − 94.3‰) allow for an estimation of the proportions of tetraether-bound biphytanes derived from planktonic Crenarchaeota and methanotrophic Euryarchaeota. Our data imply that the shape of AOM-derived carbonate precipitates in Black Sea environments is crucially influenced by the respective methane supply. Active AOM-driven chimney-like bioherms, similar to those previously observed on the Ukrainian shelf, might also develop in the deep euxinic zone at 1555 m water depths.
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  • 38
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    Genetic variability in Hysterothylacium aduncum, a raphidascarid nematode isolated from sprat (Sprattus sprattus) in different geographical areas of the northeastern Atlantic (2007)
    Springer
    In:  Parasitology Research, 101 (5). pp. 1425-1430.
    Details
    Publication Date: 2018-01-19
    Description: Species of the genus Hysterothylacium are among the most common marine nematode fish parasites in the northern Atlantic. Due to recent findings of cryptic speciation in other parasitic ascaridoid nematodes, a similar pattern of sibling species was hypothesized also for Hysterothylacium aduncum. By investigating a 886- to 890-bp-long genomic DNA fragment including ITS-1, 5.8S rDNA and ITS-2 of 40 specimens of H. aduncum of sprat (Sprattus sprattus) of four different biogeographical regions (North Sea, English Channel, Bay of Biscay, Adriatic Sea), we could not detect significant genetic variability and therefore cryptic speciation. Nevertheless, while ITS-1 and 5.8S rDNA sequences were identical for all analysed specimens, ITS-2 sequences showed a population-specific pattern with the differentiation of an English Channel/Bay of Biscay group from a North Sea/Mediterranean Sea group.
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  • 39
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    Sponge-specific bacterial associations in the Mediterranean sponge Chondrilla nucula (Demospongiae, Tetractinomorpha) (2007)
    Springer
    In:  Microbial Ecology, 54 (1). pp. 101-111.
    Details
    Publication Date: 2017-03-22
    Description: A stable and specific bacterial community was shown to be associated with the Mediterranean sponge Chondrilla nucula. The associated bacterial communities were demonstrated to be highly similar for all studied specimens regardless of sampling time and geographical region. In addition, analysis of 16S rDNA clone libraries revealed three constantly C. nucula-associated bacterial phylotypes belonging to the Acidobacteria, the Gamma- and Deltaproteobacteria present in sponge specimens from two Mediterranean regions with distinct water masses (Ligurian Sea and Adriatic Sea). For the first time, candidate division TM7 bacteria were found in marine sponges. A major part (79%) of the C. nucula-derived 16S rDNA sequences were closely related to other sponge-associated bacteria. Phylogenetic analysis identified 14 16S rRNA gene sequence clusters, seven of which consisted of exclusively sponge-derived sequences, whereas the other seven clusters contained additional environmental sequences. This study adds to a growing database on the stability and variability of microbial consortia associated with marine sponges.
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  • 40
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    Simultaneous determination of safflor yellow A, puerarin, daidzein, ginsenosides (Rg1, Rb1, Rd), and notoginsenoside R1 in rat plasma by liquid chromatography-mass spectrometry (2007)
    Elsevier
    In:  Journal of Pharmaceutical and Biomedical Analysis, 45 (2). pp. 327-336.
    Details
    Publication Date: 2017-10-05
    Description: A liquid chromatograph/mass spectrometry (LC/MS) method was developed for the simultaneous quantitation of seven compounds (safflor yellow A, puerarin, daidzein, ginsenosides (Rg(1), Rb(1), Rd), and notoginsenoside R(1)) in rat plasma samples with sufficient sensitivity to facilitate analysis of samples collected after an intravenous injection of Naodesheng. The plasma samples were subjected to protein precipitation with acetone, and analyzed using negative atmospheric pressure chemical ionization mass spectrometry in selected ion monitoring (SIM) mode with baicalin as an internal standard. Good linearity for all the seven compounds was observed. The intra- and inter-day precision of analysis was 〈15.0% for each compound, and the accuracy ranged from 90.0% to 109.0%. This quantitation method was successfully applied to a pharmacokinetic study of following intravenous injection of rats with Naodesheng
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  • 41
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    Calcium isotope fractionation in calcite and aragonite (2005)
    Elsevier
    In:  Geochimica et Cosmochimica Acta, 69 (18). pp. 4485-4494.
    Details
    Publication Date: 2017-09-08
    Description: Calcium isotope fractionation was measured on skeletal aragonite and calcite from different marine biota and on inorganic calcite. Precipitation temperatures ranged from 0 to 28°C. Calcium isotope fractionation shows a temperature dependence in accordance with previous observations: 1000 · ln(αcc) = −1.4 + 0.021 · T (°C) for calcite and 1000 · ln(αar) = −1.9 + 0.017 · T (°C) for aragonite. Within uncertainty the temperature slopes are identical for the two polymorphs. However, at all temperatures calcium isotopes are more fractionated in aragonite than in calcite. The offset in δ44/40Ca is about 0.6‰. The underlying mechanism for this offset may be related to the different coordination numbers and bond strengths of the calcium ions in calcite and aragonite crystals, or to different Ca reaction behavior at the solid-liquid interface. Recently, the observed temperature dependence of the Ca isotope fractionation was explained quantitatively by the temperature control on precipitation rates of calcium carbonates in an experimental setting (Lemarchand et al., 2004). We show that this mechanism can in principle also be applied to CaCO3 precipitation in natural environments in normal marine settings. Following this model, Ca isotope fractionation in marine Ca carbonates is primarily controlled by precipitation rates. On the other hand the larger Ca isotope fractionation of aragonite compared to calcite can not be explained by different precipitation rates. The rate control model of Ca isotope fractionation predicts a strong dependence of the Ca isotopic composition of carbonates on ambient CO32− concentration. While this model is in general accordance with our observations in marine carbonates, cultured specimens of the planktic foraminifer Orbulina universa show no dependence of Ca-isotope fractionation on the ambient CO32− concentration. The latter observation implies that the carbonate chemistry in the calcifying vesicles of the foraminifer is independent from the ambient carbonate ion concentration of the surrounding water.
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  • 42
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    Fumarolic gases at Mombacho Volcano (Nicaragua): presence of magmatic gas species and implications for volcanic surveillance (2007)
    Springer
    In:  Bulletin of Volcanology, 69 (7). pp. 785-795.
    Details
    Publication Date: 2019-09-23
    Description: Mombacho is a deeply dissected volcano belonging to the Quaternary volcanic chain of Nicaragua. The southern, historic collapse crater (El Crater) currently hosts a fumarolic field with a maximum temperature of 121°C. Chemical and isotopic data from five gas-sampling field campaigns carried out in 2002, 2003 and 2005 highlight the presence of high-temperature gas components (e.g. SO2, HCl and HF), which indicate a significant contribution of juvenile magmatic fluids to the hydrothermal system feeding the gas discharges. This is strongly supported by the mantle-derived helium and carbon isotopic signatures, although the latter is partly masked by either a sedimentary subduction-related or a shallow carbonate component. The observed chemical and isotopic composition of the Mombacho fluids seems to indicate that this volcanic system, although it has not experienced eruptive events during the last centuries, can be considered active and possibly dangerous, in agreement with the geophysical data recorded in the region. Systematic geochemical monitoring of the fumarolic gas discharges, coupled with a seismic and ground deformation network, is highly recommended in order to monitor a possible new eruptive phase.
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  • 43
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    Holocene environmental history recorded in Lake Lyadhej-To sediments, Polar Urals, Russia (2005)
    Elsevier
    In:  Palaeogeography, Palaeoclimatology, Palaeoecology, 223 (3-4). pp. 181-203.
    Details
    Publication Date: 2015-01-22
    Description: An 1180-cm long core recovered from Lake Lyadhej-To (68°15′ N, 65°45′ E, 150 m a.s.l.) at the NW rim of the Polar Urals Mountains reflects the Holocene environmental history from ca. 11,000 cal. yr BP. Pollen assemblages from the diamicton (ca. 11,000–10,700 cal. yr BP) are dominated by Pre-Quaternary spores and redeposited Pinaceae pollen, pointing to a high terrestrial input. Turbid and nutrient-poor conditions existed in the lake ca. 10,700–10,550 cal. yr BP. The chironomid-inferred reconstructions suggest that mean July temperature increased rapidly from 10.0 to 11.8 °C during this period. Sparse, treeless vegetation dominated on the disturbed and denuded soils in the catchment area. A distinct dominance of planktonic diatoms ca. 10,500–8800 cal. yr BP points to the lowest lake-ice coverage, the longest growing season and the highest bioproductivity during the lake history. Birch forest with some shrub alder grew around the lake reflecting the warmest climate conditions during the Holocene. Mean July temperature was likely 11–13 °C and annual precipitation—400–500 mm. The period ca. 8800–5500 cal. yr BP is characterized by a gradual deterioration of environmental conditions in the lake and lake catchment. The pollen- and chironomid-inferred temperatures reflect a warm period (ca. 6500–6000 cal. BP) with a mean July temperature at least 1–2 °C higher than today. Birch forests disappeared from the lake vicinity after 6000 cal. yr BP. The vegetation in the Lyadhej-To region became similar to the modern one. Shrub (Betula nana, Salix) and herb tundra have dominated the lake catchment since ca. 5500 cal. yr BP. All proxies suggest rather harsh environmental conditions. Diatom assemblages reflect relatively short growing seasons and a longer persistence of lake-ice ca. 5500–2500 cal. yr BP. Pollen-based climate reconstructions suggest significant cooling between ca. 5500 and 3500 cal. yr BP with a mean July temperature 8–10 °C and annual precipitation—300–400 mm. The bioproductivity in the lake remained low after 2500 cal. yr BP, but biogeochemical proxies reflect a higher terrestrial influx. Changes in the diatom content may indicate warmer water temperatures and a reduced ice cover on the lake. However, chironomid-based reconstructions reflect a period with minimal temperatures during the lake history.
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  • 44
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    Using thermoterrace dimensions to calculate the coastal erosian rate (2005)
    Springer
    In:  Geo-Marine Letters, 25 (2-3). pp. 121-126.
    Details
    Publication Date: 2015-01-22
    Description: Thermoterraces in syngenetic ice complexes are widespread along the erosion dominated Yakutia Arctic coast. Thermoterraces progressively record quantitative information about their existence, which may be used to determine the mean shore retreat rate during the time they are present. Initial measurements of four thermoterraces on the south coast of the Dmitry Laptev Strait were carried out by the authors in 2002 and shore retreat rates were calculated. Comparison of erosion rates obtained using thermoterrace dimensions and geodetic survey results with those determined using aerial photographs showed that erosion rate values obtained in these two ways are approximately of the same order.
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  • 45
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    Oxygen isotope fractionation during synthesis of CaMg-carbonate and implications for sedimentary dolomite formation (2005)
    Elsevier
    In:  Geochimica et Cosmochimica Acta, 69 . pp. 4665-4674.
    Details
    Publication Date: 2017-08-09
    Description: Hydrous CaMg-carbonate was synthesized at temperatures of 40 degrees, 60 degrees and 80 degrees C in the laboratory. This material has very similar mineralogical characteristics to natural disordered dolomite from the Coorong region in South Australia. Besides the dolomite variable amounts of amorphous carbonate are present in all samples. The oxygen isotope compositions of synthesized bulk carbonate samples (e.g., amorphous carbonate plus dolomite) plot significantly lower than the Northrop and Clayton (1966) dolomite-water equilibrium. Fractionated degassing of the samples, however, revealed relatively low oxygen isotope values for fast-reacting (using 100% H3PO4) amorphous carbonate. In contrast, slow-reacting dolomite has more positive oxygen isotope values, and calculated carbonate-water oxygen isotope fractionation values are close to strongest known dolomite-water oxygen isotope fractionation published earlier on. Variations of reaction/stabilization temperatures during synthesis gave evidence for dolomite formation from hypersaline solutions by a dissolution/reprecipitation process. It is likely that amorphous carbonate has been a problem in defining the dolomite-water fractionation in the past. Moreover, dolomite-associated amorphous carbonate contents probably led to incorrect speculations about lower oxygen isotope fractionation in a so-called protodolomite-water system. Copyright (c) 2005 Elsevier Ltd.
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  • 46
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    Sedimentology in the 21st century - a tribute to Wolfgang Schlager: editorial (2005)
    Elsevier
    In:  Sedimentary Geology, 175 . pp. 3-8.
    Details
    Publication Date: 2018-07-19
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  • 47
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    The temporal variability of Centropages typicus in the Mediterranean Sea: From seasonal to decadal scales (2007)
    Elsevier
    In:  Progress in Oceanography, 72 . pp. 214-232.
    Details
    Publication Date: 2016-10-05
    Description: Centropages typicus is one of the most common, abundant and best studied calanoid copepods in neritic waters of the Mediterranean Sea, which means it can provide useful information about the long-term dynamics of the Mediterranean epipelagic ecosystem. This paper presents the first comparative overview of the seasonal and long-term variability of C. typicus in different Mediterranean regions. This review is based on quantitative information from the published literature and novel data from five ongoing zooplankton time-series carried out in the Mallorca Island (Balearic Sea), the Bay of Villefranche (Ligurian Sea), the Gulf of Naples (Tyrrhenian Sea), the Gulf of Trieste (North Adriatic Sea), and the Saronikos Gulf (Aegean Sea). In most Mediterranean regions, C. typicus has a perennial occurrence, with peaks of abundance that reflect the succession of different generations. Throughout the Mediterranean, the annual cycle of C. typicus is characterized by minima in winter and major peaks in April–June, which is earlier than those observed in European Atlantic waters, where the peaks are more frequently recorded in summer and fall. In the regions investigated, the annual cycle shows remarkable similarities in terms of timing, but notable differences in the peak height; populations are far more abundant in coastal north-western regions and less abundant in the eastern basin. In the long-term, changes in C. typicus phenology observed in the Bay of Villefranche and in the Gulf of Naples are related to the North Atlantic Oscillation (NAO) index. In these two regions, the species responds to climate forcing similarly in terms of average seasonal patterns (bi-modal patterns in years of positive NAO, unimodal patterns in years of negative NAO) but oppositely in terms of quantity, indicating different influence of the NAO on the two regions. At decadal scales, C. typicus populations show high interannual variability with marked geographical differences. In some areas, the patterns are clearly characterized by alternate phases of higher and lower annual abundances, at higher frequency (mainly 1–2 years) in the Gulf of Naples, and lower frequency in the Saronikos Gulf (mainly 4–5 years) and in the Gulf of Trieste (mainly 5–6 years). Synchronous phases of increasing or decreasing abundance are discernable only for a few sites and short periods, for example from 1998 to 2000 in the Gulf of Naples, Gulf of Trieste and Saronikos Gulf. The regional differences observed in the long-term patterns of C. typicus populations suggest that the temporal dynamics of this species are significantly more affected by local conditions than by any possible common driving force acting at basin scale through teleconnections.
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  • 48
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    New Pentaenes from the Sponge-Derived Marine Fungus Penicillium rugulosum: Structure Determination and Biosynthetic Studies (2007)
    Elsevier
    In:  Tetrahedron, 63 . pp. 11844-11849.
    Details
    Publication Date: 2017-12-05
    Description: Seven new fungal polyketides possessing linear pentaene structures ending in cyclic moieties were isolated from the mycelium extract of a marine sponge-derived Penicillium rugulosum. Feeding of C-13-labeled acetate and L-methionine was used to verify the polyketide origin of prugosene A1. It could also be shown that prugosenes B1 and C1 were formed from prugosene A1 by hydrolysis and decarboxylation of its oxabicyclo[2.2.1]heptane unit.
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  • 49
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    Novel antifoulants: Inhibition of larval attachment by proteases (2007)
    Springer
    In:  Marine Biotechnology, 9 (3). pp. 388-397.
    Details
    Publication Date: 2018-01-19
    Description: We investigated the effect of commercially available enzymes (α-amylase, α-galactosidase, papain, trypsin, and lipase) as well as proteases from deep-sea bacteria on the larval attachment of the bryozoan Bugula neritina L. The 50% effective concentrations (EC50) of the commercial proteases were 10 times lower than those of other enzymes. Crude proteases from six deep-sea Pseudoalteromonas species significantly decreased larval attachment at concentrations of 0.03 to 1 mIU ml−1. The EC50 of the pure protease from the bacterium Pseudoalteromonas issachenkonii UST041101-043 was close to 1 ng ml−1 (0.1 mIU ml−1). The protease and trypsin individually incorporated in a water-soluble paint matrix inhibited biofouling in a field experiment. There are certain correlations between production of proteases by bacterial films and inhibition of larval attachment. None of the bacteria with biofilms that induced attachment of B. neritina produced proteolytic enzymes, whereas most of the bacteria that formed inhibitive biofilms produced proteases. Our investigation demonstrated the potential use of proteolytic enzymes for antifouling defense.
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  • 50
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    Polyphase faulting during the development of the west Galicia rifted margin (2005)
    Elsevier
    In:  Earth and Planetary Science Letters, 237 (3-4). pp. 561-576.
    Details
    Publication Date: 2016-12-21
    Description: Rifted margins are commonly characterised by an extension discrepancy: the amount of extension measurable from the observed faulting is far less than that required to explain the crustal thinning. It is shown here that polyphase faulting may provide a simple explanation for this paradox, but can be very hard to recognise on seismic sections. However at the west Galicia rifted margin (the Galicia Interior Basin between the Galicia Bank and the mainland, and the deep Galicia margin to the west of the Galicia Bank), a combination of high quality depth images, seismic velocity information and stratigraphic control through ODP drilling and submersible sampling, provide complementary evidence for polyphase faulting. Berriasian–Hauterivian rifting in the Galicia Interior Basin occurred along two sets of faults: the first unroofed deep crustal rocks, evidenced by high seismic velocities close to top basement; the second cut and dismembered these early faults. Further rifting (up until the Aptian) then focussed west of the Galicia Bank, where two further phases of faulting can be inferred from the diachronous nature of seismostratigraphic units tilted within fault blocks. Removal of the latest phase of faulting aligns discontinuous reflections within the fault blocks into an anastomosing network of earlier faults; restoration along these brings the crust back to its early Hauterivian state, similar to the present structure of the Interior Basin.
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  • 51
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    Spatial variations of methanothrophic consortia at cold methane seeps: implications from a high-resolution molecular and isotopic approach (2005)
    Wiley
    In:  Geobiology, 334 . pp. 195-209.
    Details
    Publication Date: 2017-06-27
    Description: Anaerobic methane-oxidizing microbial communities in sediments at cold methane seeps are important factors in controlling methane emission to the ocean and atmosphere. Here, we investigated the distribution and carbon isotopic signature of specific biomarkers derived from anaerobic methanotrophic archaea (ANME groups) and sulphate-reducing bacteria (SRB) responsible for the anaerobic oxidation of methane (AOM) at different cold seep provinces of Hydrate Ridge, Cascadia margin. The special focus was on their relation to in situ cell abundances and methane turnover. In general, maxima in biomarker abundances and minima in carbon isotope signatures correlated with maxima in AOM and sulphate reduction as well as with consortium biomass. We found ANME-2a/DSS aggregates associated with high abundances of sn-2,3-di-O-isoprenoidal glycerol ethers (archaeol, sn-2-hydroxyarchaeol) and specific bacterial fatty acids (C16:1ω5c, cyC17:0ω5,6) as well as with high methane fluxes (Beggiatoa site). The low to medium flux site (Calyptogena field) was dominated by ANME-2c/DSS aggregates and contained less of both compound classes but more of AOM-related glycerol dialkyl glycerol tetraethers (GDGTs). ANME-1 archaea dominated deeper sediment horizons at the Calyptogena field where sn-1,2-di-O-alkyl glycerol ethers (DAGEs), archaeol, methyl-branched fatty acids (ai-C15:0, i-C16:0, ai-C17:0), and diagnostic GDGTs were prevailing. AOM-specific bacterial and archaeal biomarkers in these sediment strata generally revealed very similar δ13C-values of around −100. In ANME-2-dominated sediment sections, archaeal biomarkers were even more 13C-depleted (down to −120), whereas bacterial biomarkers were found to be likewise 13C-depleted as in ANME-1-dominated sediment layers (δ13C: −100). The zero flux site (Acharax field), containing only a few numbers of ANME-2/DSS aggregates, however, provided no specific biomarker pattern. Deeper sediment sections (below 20 cm sediment depth) from Beggiatoa covered areas which included solid layers of methane gas hydrates contained ANME-2/DSS typical biomarkers showing subsurface peaks combined with negative shifts in carbon isotopic compositions. The maxima were detected just above the hydrate layers, indicating that methane stored in the hydrates may be available for the microbial community. The observed variations in biomarker abundances and 13C-depletions are indicative of multiple environmental and physiological factors selecting for different AOM consortia (ANME-2a/DSS, ANME-2c/DSS, ANME-1) along horizontal and vertical gradients of cold seep settings.
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  • 52
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    Elemental distribution in cephalopod statoliths: NanoSIMS provides new insights into nano-scale structure (2007)
    Springer
    In:  Reviews in Fish Biology and Fisheries, 17 . pp. 487-491.
    Details
    Publication Date: 2021-08-27
    Description: We have applied the novel analytical method NanoSIMS to cephalopod statoliths for the first time in order to analyse their chemical microstructure, using a spatial resolution of 400 nm. This technique makes it possible to analyse in situ nano-scale chemical variations between increment layers. In statoliths of the boreoatlantic armhook squid Gonatus fabricii, we found distinct concentration patterns indicating a periodicity in strontium and sodium distributions. Sr and Na show a negative relation, both elements showing alternating patterns where the increments vary in width between approximately 1 and 5 μm. Results suggest, that aragonite deposited during the night is rich in Na and poor in Sr, while aragonite deposited during the day is rich in Sr and poor in Na. This study demonstrates the excellent suitability of NanoSIMS for nano-scale microchemical analyses of aragonite, providing new information on calcification processes and individual life histories. Possible future fields of application include not only cephalopod statoliths, but also virtually all biomineralized tissues in aquatic organisms like fish otoliths, gastropod statoliths, bivalve shells, foraminifers and corals.
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  • 53
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    History of freshwater runoff across the Laptev Sea (Arctic) during the last deglaciation (2005)
    Elsevier
    In:  Global and Planetary Change, 48 (1-3). pp. 187-207.
    Details
    Publication Date: 2017-09-13
    Description: Sediment core PS2458 from the Laptev Sea continental margin (983-m water depth) stems from a position close to the paleoriver mouth of Lena and Yana rivers. It was dated by AMS-14C and analyzed in high resolution for oxygen isotopes of planktic foraminifers. Except the uppermost 100 cm and possibly the lowermost meter of the 8-m-long core, the sediments were deposited during the last deglaciation (14.5–8.0 cal-ka). According to 210Pb data, the uppermost 100 cm represents only the last 200 years. Planktic foraminifers are present throughout the dated deglacial interval, with the exception of a short time after ca. 13 cal-ka. Taking into account the global “ice volume effect” on the oxygen isotopic composition of the foraminifers, the isotopic record is considered to reflect salinity changes which were influenced by variable freshwater runoff and a growing marine influence during the postglacial transgression of the Laptev Sea shelf. The most conspicuous feature in the isotopic record is an outstanding peak dated to ca. 13 cal-ka. It is proposed that it represents a rapid outburst of large amounts of freshwater, possibly from an ice-dammed lake in the hinterland. Possible correlations to the onset of the cool Younger Dryas event in the northern hemisphere are discussed.
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  • 54
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    Removal and bioaccumulation of anthropogenic, halogenated transient tracers in an anoxic fjord (2005)
    Elsevier
    In:  Marine Chemistry, 94 (1-4). pp. 27-41.
    Details
    Publication Date: 2017-08-22
    Description: The persistence of the anthropogenic halogenated tracers, CFC-11 (CCl3F), CFC-12 (CCl2F2), CFC-113 (CCl2FCClF2), carbon tetrachloride (CCl4) and methyl chloroform (CH3CCl3) in oxygen-depleted waters was investigated in the anoxic fjord Framvaren in southern Norway. A model for the ventilation of the water in the fjord was created based on tritium and CFC-12 profiles. The results suggest that CFC-12 is stable in this environment, although still affected by particulate scavenging, while the other four halocarbon species shows signs of significant removal in the oxic/anoxic interface. The first-order removal coefficients were calculated to be 0.35, 0.19, 1.23 and 0.31 year−1 for CFC-11, CFC-113, CCl4 and CH3CCl3, respectively. Significant downward flux of halogenated tracers by sinking organic matter is suggested by the model; the tracers are subsequently released to the water column by the remineralisation of the particles. This process acts as a sink of halogenated tracers in the surface waters, whereas it is a source for the deep waters. Our results points to bioaccumulation factors (BF) for the CFC tracers in the order of 4.4–5.4 (log BF), which is 100–600 times those previously reported. This might be of significance to near-shore, semi-enclosed, basins with a high flux of organic matter, but would still have little importance in open ocean basins.
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  • 55
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    Objective analyses of hydrographic data for referencing profiling float salinities in highly variable environments (2005)
    Elsevier
    In:  Deep Sea Research Part II: Topical Studies in Oceanography, 52 (3-4). pp. 651-664.
    Details
    Publication Date: 2020-08-05
    Description: The development of a broad-scale array of about 3000 autonomous profiling floats, known as Argo, has been underway since 2000. This array will deliver up to 100,000 vertical profiles of temperature, salinity and other parameters from the surface to depths up to 2000 m. While floats are expected to give good measurements of temperature and pressure, salinity measurements sometimes show significant sensor drift with time or offsets. Unless a float is recovered before the battery fails, recalibrations cannot be performed and a remote calibration method is required. Such a quality control system has been set up for the North Atlantic to identify and correct salinity sensor drifts by using historical hydrographic data. An objective mapping method is used that takes the spatial and temporal variations in water mass properties into account. These scales aim to represent the hydrographic structure of the North Atlantic, which follow the large-scale contours of the potential vorticity. The float measurements of each profile are compared to the mapped salinities in potential conductivity space by weighted least-squares, giving one correction for each profile. It is assumed that any conductivity offset changes slowly over time, so that a linear fit of the profile based corrections over the float time series is done. The result is a set of calibrated salinity data with corresponding uncertainties.
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  • 56
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    The first sorbicillinoid alkaloids, the antileucemic sorbillactones A and B, from a sponge derived Penicillium chrysogenum strain (2005)
    Elsevier
    In:  Tetrahedron (61). pp. 7252-7265.
    Details
    Publication Date: 2019-01-24
    Description: The saltwater culture of a Penicillium chrysogenum strain isolated from the Mediterranean sponge Ircinia fasciculata yielded three new sorbicillin-derived compounds (1-3), whose structures were elucidated mainly by 2D NMR and mass spectrometry. Among them, sorbicillactones A (1) and B (2) are the first sorbicillinoid natural products that contain nitrogen. Compound 1 is anti-HIV active and it exhibits a strong cytotoxic activity against L5178y leukemic cells, combined with a relatively low toxicity to cervical carcinoma HeLa S3 cells and pheochromocytoma PC 12 cells. The absolute configurations of I and 2 were elucidated by quantum chemical calculation of circular dichroism (CD) spectra. Another compound isolated, sorbivinetone (3), might be an artifact derived from sorbicillinol (4) by Diels-Alder reaction with ethyl vinyl ether. Furthermore, the known sorbicillinoid fungal metabolites oxosorbicillinol (5), sorbicillin (6), and bisvertinolone (7) were identified, as well as the alkaloids meleagrine and roquefortine C. The biosynthetic origin of sorbicillactone A (1) from acetate, alanine, and methionine was investigated by feeding experiments with C-13-labeled precursors
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  • 57
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    Phase relationship and surface water mass change in the Northeast Atlantic during Marine Isotope Stage 11 (MIS 11) (2007)
    Elsevier
    In:  Quaternary Research, 68 (3). pp. 445-455.
    Details
    Publication Date: 2016-09-19
    Description: Planktic foraminiferal census data, faunal sea surface temperatures (SSTs) and oxygen isotopic and lithic records from a site in the northeast Atlantic were analyzed to study the interglacial dynamics of Marine Isotope Stage (MIS) 11, a period thought to closely resemble the Holocene on the basis of orbital forcing. Interglacial conditions during MIS 11 persisted for approximately 26 ka. After the main deglacial meltwater processes ceased, a 10- to 12-ka-long transitional period marked by significant water mass circulation changes occurred before surface waters finally reached their thermal maximum. This SST peak occurred between 400 and 397 ka, inferred from the abundance of the most thermophilic foraminiferal species and was coincident with lowest sea level according to benthic isotope values. The ensuing stepwise SST decrease characterizes the overall climate deterioration preceding the increase in global ice volume by ∼ 3 ka. This cooling trend was followed by a more pronounced cold event that began at 388 ka, and that terminated in the recurrence of icebergs at the site around 382 ka. Because the water mass configuration of early MIS 11 evolved quite differently from that of the early Holocene, there is little evidence that MIS 11 can serve as an appropriate analogue for a future Holocene climate, despite the similarity in some orbital parameters.
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  • 58
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    Textural and mineralogical changes associated with the incipient hydrothermal alteration of glassy dacite at the submarine PACMANUS hydrothermal system, eastern Manus Basin (2007)
    Elsevier
    In:  Journal of Volcanology and Geothermal Research, 160 . pp. 23-41.
    Details
    Publication Date: 2017-07-24
    Description: Variably altered dacite from the PACMANUS vent field in the eastern Manus back-arc basin, Papua New Guinea, was studied to determine the textural and mineralogical characteristics of hydrothermal alteration taking place in the immediate subsurface of this modern seafloor hydrothermal system. Detailed textural investigations show that fluid flow through the glassy dacite has been strongly controlled by the primary volcanic textures. Quench fractures and networks of interconnected perlitic cracks linking vesicles provided pathways for hydrothermal fluids flowing up to the seafloor. Hydrothermal alteration along these pathways resulted in the formation of pseudoclastic textures. Textural evidence suggests that alteration of the glassy dacite has not been sustained. The samples have been affected by incipient hydrothermal alteration that is typically not preserved in ancient volcanic-rock-hosted massive sulfide deposits. Interaction of the glassy dacite with hydrothermal fluids primarily resulted in the conversion of volcanic glass to dioctahedral smectite. Only minor amounts of trioctahedral smectite were formed. Destruction of the volcanic glass and the formation of smectite caused pronounced changes in the chemistry of the dacite samples, in particular a decrease in the SiO2 whole-rock content and the Na2O/K2O ratio. The two alkali elements behaved differently during hydrothermal alteration due to preferential incorporation of K into the interlayer position of the newly formed dioctahedral smectite. Smectite formation occurred under rock-dominated conditions although the addition of Mg was required to form trioctahedral smectite from the silicic volcanic glass. Primary plagioclase was resistant to hydrothermal alteration highlighting the fact that the destruction of volcanic glass and feldspar are not necessarily contemporaneous in massive sulfide forming hydrothermal systems. Incipient alteration of the glassy dacite close to the seafloor occurred at temperatures below 150 °C in an environment that allowed the development of steep temperature gradients. Comparison of the new data to the findings of deep drilling during ODP Leg 193 suggests that the smectite-rich alteration in the immediate subsurface of the PACMANUS hydrothermal vent field represents the low-temperature equivalent of illite- and chlorite-rich alteration associations forming in the upflow zones of the hydrothermal fluids in the deeper portion of the volcanic sequence.
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  • 59
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    Differing controls over the Cenozoic Pb and Nd isotope evolution of deepwater in the central North Pacific Ocean (2005)
    Elsevier
    In:  Earth and Planetary Science Letters, 232 . pp. 345-361.
    Details
    Publication Date: 2016-12-21
    Description: Dissolved Pb and Nd isotope ratios of seawater, as recorded by chemical marine precipitates such as hydrogenetic ferromanganese crusts, have been used as paleoenvironmental proxy tracers. For the North Pacific, however, all ferromanganese crusts studied so far have either been subject to phosphatization or hydrothermal influence in their old part, or only the young parts have been analyzed. Thus, the Pb and Nd isotope compositions of North Pacific deep waters prior to ∼20 Ma are not well constrained. We present new results for three ferromanganese crusts, one of which (CJ01) shows no phosphatization and is located far away from the EPR. Its age is inferred to be ∼75 Ma and thus provides for the first time an opportunity to trace the Nd and Pb isotope evolution of central North Pacific seawater back to the latest Cretaceous. The three crusts, no matter whether phosphatized or not, display very similar Pb and Nd isotope trends with age, suggesting no modification of the Pb and Nd isotope distribution by post-depositional phosphatization. Our data suggest that dissolved Pb in deep waters of the central North Pacific over the Cenozoic and latest Cretaceous has mainly been derived from eolian dust and only to a minor extent from weathering of island arcs. For Pb these trends broadly resemble the Pb isotope evolution of the eolian silicate dust fraction of core LL44-GPC3 in the central North Pacific. We suggest that the isotope evolution of dissolved Pb in central North Pacific seawater has been mainly controlled by Pb released from eolian dust from North America prior to 50 Ma and after 40 Ma from Asia. In contrast, the Nd isotope time series of the crusts are by no means similar to the Nd isotope evolution of the silicate dust fraction in core GPC3, suggesting a decoupling from the Pb and negligible contributions from dust to the dissolved Nd in the central North Pacific deep water. The rise of Nd isotope ratios of Pacific seawater during the Cenozoic has most likely been caused by the increasing volcanic activity and erosion of the volcanic arcs around the Pacific.
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  • 60
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    An indoor mesocosm system to study the effect of climate change on the late winter and spring succession of Baltic Sea phyto- and zooplankton (2007)
    Springer
    In:  Oecologia, 150 (4). pp. 655-667.
    Details
    Publication Date: 2019-09-23
    Description: An indoor mesocosm system was set up to study the response of phytoplankton and zooplankton spring succession to winter and spring warming of sea surface temperatures. The experimental temperature regimes consisted of the decadal average of the Kiel Bight, Baltic Sea, and three elevated regimes with 2°C, 4°C, and 6°C temperature difference from that at baseline. While the peak of the phytoplankton spring bloom was accelerated only weakly by increasing temperatures (1.4 days per degree Celsius), the subsequent biomass minimum of phytoplankton was accelerated more strongly (4.25 days per degree Celsius). Phytoplankton size structure showed a pronounced response to warming, with large phytoplankton being more dominant in the cooler mesocosms. The first seasonal ciliate peak was accelerated by 2.1 days per degree Celsius and the second one by 2.0 days per degree Celsius. The over-wintering copepod populations declined faster in the warmer mesocosm, and the appearance of nauplii was strongly accelerated by temperature (9.2 days per degree Celsius). The strong difference between the acceleration of the phytoplankton peak and the acceleration of the nauplii could be one of the “Achilles heels” of pelagic systems subject to climate change, because nauplii are the most starvation-sensitive life cycle stage of copepods and the most important food item of first-feeding fish larvae.
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  • 61
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    Climate change impacts on structure and diversity of fish communities in rivers (2007)
    Wiley
    In:  Global Change Biology, 13 . pp. 1-12.
    Details
    Publication Date: 2018-05-17
    Description: It is widely accepted that climate change constrains biota. Yet, because of the lack of consistent multisite and multitaxon surveys, few studies have addressed general rules about how climate change impacts on structure and diversity of animal communities. Especially, the relative influence of nonclimatic anthropogenic disturbances on this impact is fairly unknown. Here, we present for the first time a meta-analysis assessing the effect of global warming on stream organisms. Fish communities of large rivers in France undergoing various anthropogenic pressures showed significant increase in proportions of warm-water species and of specific richness during the last 15–25 years. Conversely, the equitability decreased, indicating a gradual decrease of the number of dominant species. Finally, the total abundance increased, coupled with rejuvenation and changes in size-structure of the communities. Interestingly, most of these effects were not depressed by the strength of nonclimatic anthropogenic disturbances. Conversely, geographical location of communities and especially closeness of natural barriers to migration could influence their response to climate change. Indeed, increase in the proportion of southern species seemed hindered at sites located close to the southern limit of the European species’ geographical ranges. This work provides new evidence that climate change have deep impacts on communities which, by overtaking the effects of nonclimatic anthropogenic disturbances, could be more substantial than previously thought. Overall, our results stress the importance of considering climate change impacts in studies addressing community dynamics, even in disturbed sites.
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  • 62
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    Growth and erosion of a cold-water coral covered carbonate mound in the Northeast Atlantic during the Late Pleistocene and Holocene (2005)
    Elsevier
    In:  Earth and Planetary Science Letters, 233 . pp. 33-44.
    Details
    Publication Date: 2016-12-21
    Description: The first detailed stratigraphic record from a deep-water carbonate mound in the Northeast Atlantic based on absolute datings (U/Th and AMS 14C) and stable oxygen isotope records reveals that its top sediment sequences are condensed by numerous hiatuses. According to stable isotope data, mainly sediments with an intermediate signal are preserved on the mound, while almost all fully glacial and interglacial sediments have either not been deposited or have been eroded later. The resulting hiatuses reduce the Late Pleistocene sediment accumulation at Propeller Mound to amounts smaller than the background sedimentation. The hiatuses most likely result due to the sweeping of the mound in turn with the re-establishment of vigour interglacial circulation patterns after sluggish current regimes during glacials. Thus, within the discussion if internal, fluid-driven or external environmentally driven processes control the evolution of such carbonate mounds, our findings for Propeller Mound clearly point to environmental forcing as the dominant mechanism shaping deep-water carbonate mounds in the NE Atlantic during the Late Pleistocene and Holocene
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  • 63
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    Late Cenomanian to Middle Turonian high-resolution carbon isotope stratigraphy: new data from the Münsterland Cretaceous Basin, Germany (2007)
    Elsevier
    In:  Earth and Planetary Science Letters, 253 . pp. 196-210.
    Details
    Publication Date: 2017-01-30
    Description: New high resolution carbon isotope stratigraphies from two basinal pelagic carbonate successions in northern Germany (Halle and Oerlinghausen, Münsterland Cretaceous Basin) resolve late Cenomanian to early Mid-Turonian carbon cycle variations at timescales of less than 100 kyr. Beside the major carbon isotope excursion of the late Cenomanian oceanic anoxic event (OAE 2), 11 small-scale distinct features are precisely resolved in the δ13C carbonate curve and related to boreal macrofossil zonations. The small-scale carbon isotope events correspond to secular δ13C carbonate variations identified previously in the English Chalk. The boreal high-resolution δ13C carbonate curve shows a detailed coincidence with two Tethyan δ13C curves from Italy, what demonstrates the interregional significance of the δ13C dates and allows their correlation within error limits of ± 40 kyr. Furthermore, the new δ13C curve enables the calibration of boreal and tethyan macro- and microfossil zonations. Accordingly, the Tethyan calcareous nannoplankton boundary NC13/NC14 corresponds to the boreal FO of C. woollgari, the index taxon for the Lower-Middle Turonian boundary. The cyclic appearance and the temporal spacing of the small-scale carbon isotope events suggest that orbital forcing exerted control on surface water productivity and organic matter preservation at the sea floor.
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  • 64
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    Intercalibration of benthic flux chambers II. Hydrodynamic characterization and flux comparisons of 14 different designs (2005)
    Elsevier
    In:  Marine Chemistry (94). pp. 147-173.
    Details
    Publication Date: 2017-08-22
    Description: We have compared 14 different sediment incubation chambers, most of them were used on bottom landers. Measurements of mixing time, pressure gradients at the bottom and Diffusive Boundary Layer thickness (DBL) were used to describe the hydrodynamic properties of the chambers and sediment–water solute fluxes of silicate (34 replicates) and oxygen (23 replicates) during three subsequently repeated incubation experiments on a homogenized, macrofauna-free sediment. The silicate fluxes ranged from 0.24 to 1.01 mmol m−2 day−1 and the oxygen fluxes from 9.3 to 22.6 mmol m−2 day−1. There was no statistically significant correlation between measured fluxes and the chamber design or between measured fluxes and hydrodynamic settings suggesting that type of chamber was not important in these flux measurements. For verification of sediment homogeneity, 61 samples of meiofauna were taken and identified to major taxa. In addition, 13 sediment cores were collected, sectioned into 5–10-mm slices and separated into pore water and solid phase. The pore water profiles of dissolved silicate were used to calculate diffusive fluxes of silicate. These fluxes ranged from 0.63 to 0.87 mmol m−2 day−1. All of the collected sediment parameters indicated that the sediment homogenization process had been satisfactorily accomplished. Hydrodynamic variations inside and between chambers are a reflection of the chamber design and the stirring device. In general, pump stirrers with diffusers give a more even distribution of bottom currents and DBL thicknesses than paddle wheel-type stirrers. Most chambers display no or low static differential pressures when the water is mixed at rates of normal use. Consequently, there is a low risk of creating stirrer induced pressure effects on the measured fluxes. Centrally placed stirrers are preferable to off-center placed stirrers which are more difficult to map and do not seem to give any hydrodynamic advantages. A vertically rotating stirrer gives about five times lower static differential pressures at the same stirring speed as the same stirrer mounted horizontally. If the aim is to simulate or mimic resuspension at high flow velocities, it cannot be satisfactorily done in a chamber using a horizontal (standing) rotating impeller (as is the case for most chambers in use) due to the creation of unnatural conditions, i.e. large static differential pressures and pre-mature resuspension at certain locations in the chamber.
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  • 65
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    Unknown
    An individual based model for the direct conversion of otolith into somatic growth rates (2007)
    Wiley
    In:  Fisheries Oceanography, 16 (3). pp. 207-215.
    Details
    Publication Date: 2019-02-27
    Description: Otolith increment width and larval fish data (length and weight) were used to develop an individual-based model (IBM) to describe daily resolved growth rates of North Sea herring (Clupea harengus) larvae (Autumn Spawners) caught during International Herring Larvae Surveys in the ICES area IVa from 1990 to 1998. The model combines sagittal otolith readings (core and individual increment measurements), larval standard length and weight data, and solves an over-determined set of linear system equations for all parameters using the method of least square residuals. The model consists of a matrix, which describes the increment width formation of 119 larvae, a vector containing their length/weight measurements, and a vector describing residuals. The solution vector yields age-dependent maximum somatic growth rates of herring larvae up to an age of 41 days with sizes ranging from 10 to 25 mm. The observed environmental temperature in which larvae dwelled was relatively uniform. Therefore, measured increment width was individually used to determine daily growth from any single larva in relation to their potential maximum growth under optimal feeding conditions. The results are discussed with respect to the spatial and temporal variability of larval occurrence. Finally, an analysis of error estimation of the larval growth characteristics is presented.
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  • 66
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    Plume-ridge interaction studied at the Galápagos spreading center: Evidence from 226Ra-230Th-238U and 231Pa-235U isotopic disequilibria (2005)
    Elsevier
    In:  Earth and Planetary Science Letters, 234 (1-2). pp. 165-187.
    Details
    Publication Date: 2016-12-21
    Description: New 238U–230Th–226Ra and 231Pa–235U disequilibria data measured by TIMS are presented for ridge-centered MORB glasses dredged during the R/V Sonne 158 cruise at the Galápagos or Cocos-Nazca Spreading Center (GSC) between 86.0°W and 92.3°W. The application of U-series isotopes to the GSC region, situated a few hundred kilometres to the north of the Galápagos hotspot, allows assessment of fundamental questions related to the dynamics of plume–ridge interaction. These include (1) the relationship between long-lived source variations, U-series disequilibria and extent of differentiation, (2) partial melting during solid upwelling, and (3) the nature and rates of plume–ridge mass transfer. The along axis U-series disequilibria variation show gradational patterns that locally are correlated with geochemical and isotopic parameters such as La/Sm, Tb/Yb, 206Pb/204Pb and 143Nd/144Nd as well as major element compositions. The correlation of (230Th)/(238U) with radiogenic isotopes and Tb/Yb provides constraints on the plume source influence on the melting process, reflecting an increase in the amount of melting at depth in the presence of garnet or aluminous clinopyroxene. Moreover, the correlation between U-series signatures, radiogenic isotopes, incompatible element abundance and MgO content indicates a causative relationship between the melting of plume source materials and how these lavas differentiate at shallow depths. We speculate that this involves loss of alkalis from ascending melts to shallow peridotite and crustal gabbro, resulting in increased olivine fractionation from the magmas. The U-series data place stringent constraints on the timing of plume–ridge mass transfer and thus distinguish whether mass transfer occurs by movement of melts or solid mantle. Within the likely conditions proposed by the model of (Braun and Sohn [EPSL 213 (2003): 417–430] and with knowledge of (231Pa)/(235U) and (230Th)/(238U) observed in Galápagos Islands lavas [A. Saal, personal communication], we show that all 226Ra excess will be lost and the initial 231Pa and 230Th excesses will be largely decayed. Therefore, we conclude that the plume influence on the GSC lavas results from a solid mantle flow process instead of through migration of plume-derived melts to the ridge.
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  • 67
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    Radical changes in the Wadden Sea fauna and flora over the last 2000 years (2005)
    Springer
    In:  Helgoland Marine Research, 59 . pp. 71-83.
    Details
    Publication Date: 2018-05-28
    Description: Humans have interacted with the Wadden Sea since its origin 7,500 years ago. However, exploitation, habitat alteration and pollution have strongly increased since the Middle Ages, affecting abundance and distribution of many marine mammals, birds, fish, invertebrates and plants. Large whales and some large birds disappeared more than 500 years ago. Most small whales, seals, birds, large fish and oysters were severely reduced by the late 19th and early 20th centuries, leading to the collapse of several traditional fisheries. In the 20th century, conservation efforts have enabled some breeding birds and seals to recover. But other species declined further due to continuing exploitation, habitat destruction, pollution and eutrophication. Moreover, complex three-dimensional habitats such as oyster banks, Sabellaria reefs and subtidal eelgrass beds have been lost completely. In contrast, several opportunistic species such as gulls, polychaetes, green algae and exotic invaders increased during the 20th century. Taken together, multiple human impacts have caused dramatic losses of large predators and habitat-building species in the Wadden Sea over the last 500 years. Although still of high natural value and global importance, the Wadden Sea is a fundamentally changed ecosystem. On the other hand, reduced hunting pressure, increased habitat protection and reduced river pollution have enabled the recent recovery of several species and an increase in environmental quality. These successes, together with a historical vision of what was once possible, should guide current and future conservation, restoration and management efforts towards a more sustainable interaction between man and the sea.
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  • 68
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    Northern ice discharges and Antarctic warming: could ocean eddies provide the link? (2005)
    Elsevier
    In:  Quaternary Science Reviews, 24 (16-17). pp. 1809-1820.
    Details
    Publication Date: 2016-09-16
    Description: A mechanism is advanced for explaining the Antarctic warm events from 90 to 30ka BP which involves meltwater-induced changes in the salinity gradient across the Antarctic Circumpolar Current (ACC) and consequent changes in the poleward heat transport by ocean eddies. Based on simple linear scale analysis, the mechanism is shown to yield warming in the Antarctic interior of roughly the magnitude seen in Antarctic ice-core records (∼2 °C) in response to ice discharges into the North Atlantic. Consistent with observations, the mechanism produces gradual Antarctic warming and cooling, as dictated by the time required for salinity anomalies to build up and dissipate across the ACC. The mechanism also allows the onset of warming or cooling to be tied to changes in Atlantic overturning, which is relevant here, not for influencing ocean heat transport directly, but for influencing the routing of meltwater from the North Atlantic into the Southern Ocean. The ideas presented here highlight the possibility that eddy processes in the ocean may play a first-order role in aspects of climate variability on millennial time scales.
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  • 69
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    Human transformations of the Wadden Sea ecosystem through time: a synthesis (2005)
    AWI | Springer
    In:  Helgoland Marine Research, 59 . pp. 84-95.
    Details
    Publication Date: 2019-08-06
    Description: Todayrsquos Wadden Sea is a heavily human-altered ecosystem. Shaped by natural forces since its origin 7,500 years ago, humans gradually gained dominance in influencing ecosystem structure and functioning. Here, we reconstruct the timeline of human impacts and the history of ecological changes in the Wadden Sea. We then discuss the ecosystem and societal consequences of observed changes, and conclude with management implications. Human influences have intensified and multiplied over time. Large-scale habitat transformation over the last 1,000 years has eliminated diverse terrestrial, freshwater, brackish and marine habitats. Intensive exploitation of everything from oysters to whales has depleted most large predators and habitat-building species since medieval times. In the twentieth century, pollution, eutrophication, species invasions and, presumably, climate change have had marked impacts on the Wadden Sea flora and fauna. Yet habitat loss and overexploitation were the two main causes for the extinction or severe depletion of 144 species (~20% of total macrobiota). The loss of biodiversity, large predators, special habitats, filter and storage capacity, and degradation in water quality have led to a simplification and homogenisation of the food web structure and ecosystem functioning that has affected the Wadden Sea ecosystem and coastal societies alike. Recent conservation efforts have reversed some negative trends by enabling some birds and mammals to recover and by creating new economic options for society. The Wadden Sea history provides a unique long-term perspective on ecological change, new objectives for conservation, restoration and management, and an ecological baseline that allows us to envision a rich, productive and diverse Wadden Sea ecosystem and coastal society.
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  • 70
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    An evaluation of reactive fluid flow and trace-element mobility in subducting slabs (2007)
    Elsevier
    In:  Chemical Geology, 239 . pp. 199-216.
    Details
    Publication Date: 2017-12-06
    Description: Permeabilities in the subducting slab appear to be too low and dihedral angles between fluid and relevant minerals too high to allow for porous flow, hence fluid channelization is critical for the understanding of subduction zone fluid fluxes. In this review we will outline how fluid channelization controls reaction rates and element redistributions during metamorphism of the subducting plate as well as trace element compositions of subduction-related fluids during flow. Channelized fluid flow predicts that from a rock point of view, most formerly subducted material will show only very limited evidence for fluid flow, consistent with the rarity of observed high fluid fluxes in subduction-related rocks. Aqueous fluid produced by dehydration reactions will not percolate through large rock volumes, but rather will be carried away from the dehydration sites by a veining network. Indeed evidence for significant aqueous-fluid fluxes have been found in high-pressure veins with adjacent selvages. In such selvages, large lithophile elements (LILE's) generally show the highest mobilities, followed by light (L) rare earth elements (REE) and then heavy (H) REE. Compared to high field strength elements (HFSE), even Th shows higher mobilities. From a fluid point of view, equilibrium between aqueous fluid and surrounding rock will only be approached at sites of fluid production and mineral reaction. However, this fluid can be significantly modified while moving upwards through a veining network where the wallrocks are out of equilibrium with the fluid. In a subducting slab, such reactive fluid flow can preferentially dissolve minerals and release their trace elements (e.g. Ba in phengite, Th and La in monazite). The degree of change in aqueous-fluid composition will depend on the amount of fluid–mineral surface interaction. The chemical exchange reactions will not be possible to model by trace element partition coefficients alone, instead future models need to incorporate kinetic parameters such as surface reaction rates.
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  • 71
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    The oxygen isotope evolution of seawater: A critical review of a long-standing controversy and an improved geological water cycle model for the past 3.4 billion years (2007)
    Elsevier
    In:  Earth-Science Reviews, 83 (1-2). pp. 83-122.
    Details
    Publication Date: 2019-09-23
    Description: Controversy over the oxygen isotope composition of seawater began in the 1950's, since which time there has been no agreement over whether the oxygen isotope composition of the oceans has changed over time. Resolving this uncertainty would allow the δ18O values of demonstrably well preserved marine authigenic precipitates to be used to reconstruct surface climate trends back to early Archean times and would help towards a more quantitative description of Earth's global water cycle on geological time scales. Isotopic studies of marine carbonate and silica reveal a trend of increasing δ18O values with decreasing age since the Archean. This trend has been interpreted by some to reflect a progressive increase in seawater δ18O through time; however, it is generally accepted on the basis of ophiolite studies and theoretical considerations that seawater δ18O cannot change significantly because of the buffering effects of ocean crust alteration at mid-ocean ridges. As a result many alternative interpretations have been proposed, including meteoric alteration; warmer paleoclimates; higher seawater pH; salinity stratification and biased sampling. Here we review these interpretations in the light of an updated compilation of marine carbonate δ18O from around the world, covering the Phanerozoic and Precambrian rock records. Recent models of the geological water cycle demonstrate how long-term trends in chemical weathering and hydrothermal circulation can indeed influence the O-isotope composition of the global ocean to the extent necessary to explain the carbonate δ18O trend, with residual variation attributed to climatic fluctuations and post-depositional alteration. We present the further development of an existing model of the geological water cycle. In the model, seawater δ18O increased from about − 13.3‰ to − 0.3‰ over a period of 3.4 Ga, with average surface temperatures fluctuating between 10 °C to 33 °C, which is consistent with known biological constraints. Similar temperature variations are also obtained, although with higher starting seawater δ18O composition, when more conservative approaches are used that take into account the systematic effects of diagenetic alteration on mean calcite δ18O values. In contrast to much published opinion, the average δ18O value of ocean crust in the model remained relatively unchanged throughout all model runs. Invariable ophiolite δ18O values can, therefore, not be used as a definitive argument against changing seawater δ18O. The most likely explanation for the long-term trend in seawater δ18O invokes two stepwise increases in the ratio of high- to low-temperature fluid/rock interactions. An initial increase may have occurred close to the Archean–Proterozoic boundary, but a possibly more significant increase took place near the Proterozoic–Phanerozoic boundary. Possible explanations for extremely low seawater δ18O during the Archean include higher continental weathering rates caused by a combination of higher atmospheric pCO2 (necessarily combined with high CO2 outgassing rates), a greater abundance of relatively easily weathered volcanic rocks in greenstone belts and partial emergence of spreading ridges. The second increase may have been caused by the suppression of low-temperature overprinting of ocean crust alteration by the formation of a thick sediment cover on ridge flanks due to the emergence of shelly plankton at the beginning of the Phanerozoic. Postulated increases in spreading ridge depths since the Archean would also have enhanced the efficiency of vertical heat flux and changed the depth at which hydrothermal fluids boil, both of which would favour high- over low-temperature interactions with time.
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  • 72
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    Reply to comment on "Gas hydrate growth, methane transport, and chloride enrichment at the southern sumnit of Hydrate Ridge, Cascadias margin off Oregon" (2005)
    Elsevier
    In:  Earth and Planetary Science Letters, 239 . pp. 168-175.
    Details
    Publication Date: 2016-12-21
    Type: Article , NonPeerReviewed
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  • 73
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    Unknown
    Is the initiation of glaciation on Antarctica related to a change in the structure of the ocean? (2005)
    Elsevier
    In:  Global and Planetary Change, 45 (1-3). pp. 23-33.
    Details
    Publication Date: 2017-07-24
    Description: Today, the ocean is characterized by pools of warm tropical–subtropical water bounded poleward and at depth by cold water. In the tropics and subtropics, the warm waters are floored at depth by the thermocline–pycnocline, which crops out on the ocean surface between the subtropical and polar frontal systems that form the poleward boundary. It is along and between the frontal systems that the thermocline waters enter the ocean interior. These frontal systems form beneath the maxima of the zonal component of the westerly winds. Today, the location of the westerly winds is stabilized by the persistent high-pressure systems at the polar regions produced by the ice cover of the Antarctic and sea-ice cover of the Arctic. The paleobiogeographic distribution of plankton fossils indicates that, prior to the Oligocene, the subtropical and polar frontal systems were not persistent features. Recent climate model experiments show that without perennial ice cover in the polar regions a seasonal alternation between high and low atmospheric pressure systems can occur. These seasonal alternations would force major changes in the location and strength of the westerly winds, preventing the development of the well-defined frontal systems that characterize the Earth today. Without the subtropical and polar frontal systems, the thermocline would be less well developed and the pycnocline could be dominated by salinity differences. Evidence from ocean drilling suggests that the glaciation of East Antarctica began at the Eocene–Oligocene boundary, but took time to spread over the entire continent. The presence of calcareous nannoplankton in the Arctic basin prior to the Oligocene and their absence thereafter suggests that the ice cover of the Arctic Ocean also developed at the Eocene–Oligocene boundary. Both events appear to be related to the development of the modern oceanic structure, but it remains uncertain whether the ocean changed in response to the development of ice covered polar regions or vice versa.
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  • 74
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    Interspecific and nutrient-dependent variations in stable isotope fractionation: experimental studies simulating pelagic multitrophic systems (2007)
    Springer
    In:  Oecologia, 154 . pp. 291-303.
    Details
    Publication Date: 2019-07-03
    Description: Stable isotope signatures of primary producers display high inter- and intraspecific variation. This is assigned to species-specific differences in isotope fractionation and variable abiotic conditions, e.g., temperature, and nutrient and light availability. As consumers reflect the isotopic signature of their food source, such variations have direct impacts on the ecological interpretation of stable isotope data. To elucidate the variability of isotope fractionation at the primary producer level and the transfer of the signal through food webs, we used a standardised marine tri-trophic system in which the primary producers were manipulated while the two consumer levels were kept constant. These manipulations were (1) different algal species grown under identical conditions to address interspecific variability and (2) a single algal species cultivated under different nutrient regimes to address nutrient-dependent variability. Our experiments resulted in strong interspecific variation between different algal species (Thalassiosira weissflogii, Dunaliella salina, and Rhodomonas salina) and nutrient-dependent shifts in stable isotope signatures in response to nutrient limitation of R. salina. The trophic enrichment in 15N and 13C of primary and secondary consumers (nauplii of Acartia tonsa and larval herring) showed strong deviations from the postulated degree of 1.0‰ enrichment in δ13C and 3.4‰ enrichment in δ15N. Surprisingly, nauplii of A. tonsa tended to keep “isotopic homeostasis” in terms of δ15N, a pattern not described in the literature so far. Our results suggest that the diets’ nutritional composition and food quality as well as the stoichiometric needs of consumers significantly affect the degree of trophic enrichment and that these mechanisms must be considered in ecological studies, especially when lower trophic levels, where variability is highest, are concerned.
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  • 75
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    Induction of defences and within-plant variation on palatability in two brown algae from the northern-central coast of Chile: effects of mesograzers and UV radiation (2005)
    Elsevier
    In:  Journal of Experimental Marine Biology and Ecology, 325 . pp. 214-227.
    Details
    Publication Date: 2018-06-29
    Description: Macroalgae possess different defense mechanisms in response to herbivory. Some species produce anti-herbivore secondary metabolites, but production of these substances can be costly. Therefore, algae may produce defensive metabolites only in response to herbivory (inducible defense) or defend particular parts of the alga differentially (within-alga variation). In the present study, we examined whether two species of brown algae from the SE-Pacific show evidence of inducible chemical defense (non-polar compounds) or within-alga variation of defense, which we estimated in form of palatability of differently treated algae to amphipod grazers (with live algae and agar-based food containing non-polar algal extracts). In Glossophora kunthii (C. Agardh) J. Agardh, we observed an increase in palatability after algae were acclimated for 12 days without grazers. Subsequent addition of grazers for 12 days then resulted in a reduction of palatability indicating the existence of inducible defense. After removal of grazers for 12 days, these induced effects again disappeared. The reaction of G. kunthii was triggered even by the mere presence of grazers, which suggests that this alga can respond to waterborne cues by reducing palatability. Effects were only found for agar-based food containing non-polar extracts, but not for live algae, suggesting that some parts of the algae are undefended. Our second experiment on within-alga variation confirmed that only apical (growth region) and basal parts (near the holdfast region) of G. kunthii are defended against herbivores. For the second species, Macrocystis integrifolia Bory, the first experiment revealed no induction of defense, while the second experiment on within-alga variation showed that amphipods avoided basal parts and in particular stipes of M. integrifolia but only in live algae. Although both studied algal species differed substantially in their defensive strategies, their reaction was independent of the presence or absence of UV radiation. Thus, it appears that UV effects play only a minor role in anti-herbivore defense, which is in accordance with most previous studies.
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  • 76
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    Unknown
    Fields of multi-kilometer scale sub-circular depressions in the Carnegie Ridge sedimentary blanket: Effect of underwater carbonate dissolution? (2005)
    Elsevier
    In:  Marine Geology, 216 (4). pp. 205-219.
    Details
    Publication Date: 2017-08-03
    Description: Offshore Ecuador, the Carnegie Ridge is a volcanic ridge with a carbonate sediment drape. During the SALIERI Cruise, multibeam bathymetry was collected across Carnegie Ridge with the Simrad EM120 of the R/V SONNE. The most conspicuous features discovered on the Carnegie Ridge are fields of circular closed depressions widely distributed along the mid-slope of the northern and southern flanks of the ridge between 1500 and 2600 m water depth. These circular depressions are 1–4 km wide and typically 100–400 m deep. Most are flat floored and some are so densely packed that they form a honeycomb pattern. The depressions were carved into the ridge sedimentary blanket, which consists of carbonate sediment and has been dated from upper Miocene to upper Pleistocene. Several hypotheses including pockmark origin, sediment creeping, paleo-topography of the volcanic basement, effects of subbottom currents, and both marine and subaerial karstic origins are discussed. We believe that underwater dissolution process merits the most serious consideration regarding the origin of the closed depression.
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  • 77
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    Unknown
    Neogene sedimentary and mass-wasting processes on the continental margin off south-central Chile inferred from dredge samples (2007)
    Elsevier
    In:  Marine Geology, 244 (1/4). pp. 166-183.
    Details
    Publication Date: 2019-09-23
    Description: The active continental margin off south-central Chile (36° to 40°S) is transitional between the tectonically erosive, empty-trench margin north of Juan Fernandez Ridge and the accretionary, trench-filled margin south of the Chile Triple Junction. The small width of the presently active accretionary wedge (maximum width of 25 to 50 km) argues for past phases of tectonic erosion. At present, this sector shows indications of contemporaneous accretion, subduction, and underplating of sediment, as well as readjustment of the slope by various mass-wasting processes. In this context, this study aims to examine the Neogene sedimentary processes on the continental margin from dredge samples recovered during R/V SONNE cruise SO161-5 within this transitional domain using lithology, sandstone petrology, shale mineralogy, and analysis of sedimentary structures. Our results yield that the principal transport of material occurs in high-energy turbidity currents and debris flows via submarine canyons deeply cutting the continental slope, whereas sediment on the shelf is transported by strong coast-parallel bottom currents and trapped by submarine canyons cutting into the shelf. A wide range of mass-wasting processes including slumping, debris flows, evolving to low-density turbidity currents and mud flows, rework the slope sediments. In contrast, thick undisturbed sequences of mostly hemipelagic sediments accumulate in active slope basins, which are largely protected from mass movements. XRD analyses revealed early diagenetic lithification and overall burial depths of up to ∼ 230 mbsf, suggesting a shallow-subsurface cycle of sedimentation, subsidence, diagenesis, uplift, erosion, and resedimentation. The composition of sandstones is dominated by volcanic rock fragments of Andean provenance. Along-strike modal changes reflect a southward increase in glacially denudation and rainfall, the combination of which caused more intense erosion of volcanic rocks and exposure, weathering and, as a result, increased fluvial transport of metamorphic and plutonic rocks to the sea.
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  • 78
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    Unknown
    Molecular analysis of the distribution and phylogeny of the soxB gene among sulfur-oxidizing bacteria - evolution of the Sox sulfur-oxidizing enzyme system (2007)
    Wiley
    In:  Environmental Microbiology, 9 (12). pp. 2957-2977.
    Details
    Publication Date: 2019-09-23
    Description: The soxB gene encodes the SoxB component of the periplasmic thiosulfate-oxidizing Sox enzyme complex, which has been proposed to be widespread among the various phylogenetic groups of sulfur-oxidizing bacteria (SOB) that convert thiosulfate to sulfate with and without the formation of sulfur globules as intermediate. Indeed, the comprehensive genetic and genomic analyses presented in the present study identified the soxB gene in 121 phylogenetically and physiologically divergent SOB, including several species for which thiosulfate utilization has not been reported yet. In first support of the previously postulated general involvement of components of the Sox enzyme complex in the thiosulfate oxidation process of sulfur-storing SOB, the soxB gene was detected in all investigated photo- and chemotrophic species that form sulfur globules during thiosulfate oxidation (Chromatiaceae, Chlorobiaceae, Ectothiorhodospiraceae, Thiothrix, Beggiatoa, Thiobacillus, invertebrate symbionts and free-living relatives). The SoxB phylogeny reflected the major 16S rRNA gene-based phylogenetic lineages of the investigated SOB, although topological discrepancies indicated several events of lateral soxB gene transfer among the SOB, e.g. its independent acquisition by the anaerobic anoxygenic phototrophic lineages from different chemotrophic donor lineages. A putative scenario for the proteobacterial origin and evolution of the Sox enzyme system in SOB is presented considering the phylogenetic, genomic (sox gene cluster composition) and geochemical data.
    Type: Article , PeerReviewed
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  • 79
    facet.materialart.
    Unknown
    Long-term annual water balance analysis of the Lena River (2005)
    Elsevier
    In:  Global and Planetary Change, 48 (1-3). pp. 84-95.
    Details
    Publication Date: 2020-12-01
    Description: Historical data analyses show that the Lena River and its major tributaries experienced an extended low water period over 1936–1957 and high water periods over 1974–1983 and 1988–2001. Higher than normal river discharge and annual precipitation is particularly pronounced since the late 1960s due to large-scale changes in atmospheric circulation patterns. The trend in runoff observed in the Lena River basin increased by 10% from 1936 to 2001 due to extended wet periods during the second part of last century. The trend is weakened for the Vilui River basin since it experiences reservoir regulation, which causes additional water losses through reservoir filling and increased evaporation. Runoff regulation strongly affects the winter runoff regime of both the Vilui River and the lower reaches of the Lena River causing an increased winter discharge at the Lena river outlet station of approximately 33%.
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  • 80
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    Unknown
    Methanogenic communities in permafrost-affected soils of the Laptev Sea coast, Siberian Arctic, characterized by 16S rRNA gene fingerprints (2007)
    Wiley
    In:  FEMS Microbiology Ecology, 59 (2). pp. 476-488.
    Details
    Publication Date: 2018-01-01
    Description: Permafrost environments in the Arctic are characterized by extreme environmental conditions that demand a specific resistance from microorganisms to enable them to survive. In order to understand the carbon dynamics in the climate-sensitive Arctic permafrost environments, the activity and diversity of methanogenic communities were studied in three different permafrost soils of the Siberian Laptev Sea coast. The effect of temperature and the availability of methanogenic substrates on CH4 production was analysed. In addition, the diversity of methanogens was analysed by PCR with specific methanogenic primers and by denaturing gradient gel electrophoresis (DGGE) followed by sequencing of DGGE bands reamplified from the gel. Our results demonstrated methanogenesis with a distinct vertical profile in each investigated permafrost soil. The soils on Samoylov Island showed at least two optima of CH4 production activity, which indicated a shift in the methanogenic community from mesophilic to psychrotolerant methanogens with increasing soil depth. Furthermore, it was shown that CH4 production in permafrost soils is substrate-limited, although these soils are characterized by the accumulation of organic matter. Sequence analyses revealed a distinct diversity of methanogenic archaea affiliated to Methanomicrobiaceae, Methanosarcinaceae and Methanosaetaceae. However, a relationship between the activity and diversity of methanogens in permafrost soils could not be shown.
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  • 81
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    The turbidity maximum zone of the Yenisei River (Siberia) and its impact on organic and inorganic proxies (2005)
    Elsevier
    In:  Estuarine, Coastal and Shelf Science, 65 (1-2). pp. 61-73.
    Details
    Publication Date: 2015-01-30
    Description: A general overview of the processes taking place in the summer mixing zone of the fresh Yenisei River water with the marine waters of the Kara Sea is given in this study, with special emphasis on the interaction between bulk (total suspended matter), inorganic (Fe, Mn) and organic (suspended organic carbon, suspended nitrogen) proxies. Within the mixing zone, a zone of enhanced turbidity (maximum turbidity zone) was observed comparable to studies in other rivers. Flocculation of particles due to changes in salinity and hydrography cause this maximum turbidity zone, and resuspension additionally enhances the turbidity in the near-bottom layers. Organic matter behaves conservatively in the mixing zone in terms of its percentage of suspended matter. It, however, undergoes degradation as revealed by amino acid data. Inorganic, redox- and salinity-sensitive, proxies (Mn, Fe) behave non-conservatively. Dissolved iron is removed at low salinities (〈2) due to precipitation of iron oxyhydroxides and adsorption of manganese on suspended particles, enhancing the Mn/Al ratio of the suspended matter in the same zone. At higher salinities within the mixing zone, Fe/Al and Mn/Al ratios of the suspended particles are depleted due to resuspension of sediment with lower Fe/Al and Mn/Al ratios. Dissolved manganese concentrations are significantly higher in the near-bottom layers of the mixing zone due to release from the anoxic sediment. All things considered, the Yenisei River mixing zone shows patterns similar to other world's rivers.
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  • 82
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    Feeding in dominant Antarctic copepods - does the morphology of the mandibular gnathobases relate to diet? (2005)
    Springer
    In:  Marine Biology, 146 (3). pp. 483-495.
    Details
    Publication Date: 2020-07-14
    Description: This study should clarify the importance of morphology and stability of the mandibular gnathobases for the diet of Antarctic copepod species. The gnathobase morphology of the dominant copepod species Calanoides acutus, Calanus propinquus, Ctenocalanus citer, Rhincalanus gigas, Metridia gerlachei, Stephos longipes, Microcalanus pygmaeus and Paraeuchaeta antarctica from the Southern Ocean was investigated in detail by means of a scanning electron microscope. The mandibular gnathobases of C. acutus, C. propinquus and C. citer have relatively short and compact teeth. These species feed mainly on diatoms and are able to crack the silicious diatom frustules with their mandibular gnathobases by directed pressure. In contrast the teeth of the mandibular gnathobases of P. antarctica are very long and pointed. The nutrition of this species consists predominantly of other smaller copepod species. The motile prey can be held by skewering, using the gnathobases, and then eventually minced. The mandibular gnathobases of P. antarctica have notably more small bristles than those of the other investigated copepod species. These bristles are probably associated with receptors and could serve to locate the prey. The morphology of the gnathobases of R. gigas and M. gerlachei is between that of P. antarctica on the one side and that of C. acutus, C. propinquus and C. citer on the other. Based on the morphology of its gnathobases the copepod species S. longipes, which has to date been found to feed primarily on phytoplankton, mainly ice algae, must also be considered a zooplankton feeder. The investigation showed that M. pygmaeus has gnathobases with surprisingly long and pointed teeth, indicating that this species very probably feeds both on phyto- and on zooplankton organisms. While the mandibular gnathobases of the males of C. propinquus, R. gigas, M. gerlachei and S. longipes have the same morphology as the females of the respective species, in the other four investigated copepod species the males have reduced (C. acutus, C. citer and M. pygmaeus) or completely missing mandibular gnathobases (P. antarctica). The teeth of the gnathobases of all studied species with the exception of M. gerlachei consist of a different material than the remaining parts of the gnathobases. This material seems to be silicate, which probably enhances the stability of the gnathobase teeth.
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  • 83
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    Depth profiles of volatile iodine and bromine-containing halocarbons in coastal Antarctic waters (2007)
    Elsevier
    In:  Marine Chemistry, 103 (3-4). pp. 227-236.
    Details
    Publication Date: 2015-01-27
    Description: Measurements of bromoform (CHBr3), diiodomethane (CH2I2), chloroiodomethane (CH2ICl) and bromoiodomethane (CH2IBr) were made in the water column (5–100 m depth) of the Southern Ocean within 0–40 km of the Antarctic sea ice during the ANTXX1/2 transect of the German R/V Polarstern, at five locations between 70–72°S and 9–11°W in the Antarctic spring/summer of 2003–2004. Some of the profiles exhibited a very pronounced layer of surface sea-ice meltwater, as evidenced by salinity minima and temperature maxima, along with surface maxima in concentrations of CHBr3, CH2I2, CH2ICl and CH2IBr. These results are consistent with in situ surface halocarbon production by ice algae liberated from the sea ice, although production within the sea ice followed by transport cannot be entirely ruled out. Additional sub-surface maxima in halocarbons occurred between 20 and 80 m. At a station further from shore and not affected by surface sea-ice meltwater, surface concentrations of CH2I2 were decreased whereas CH2ICl concentrations were increased compared to the stations influenced by meltwater, consistent with photochemical conversion of CH2I2 to CH2ICl, perhaps during upward mixing from a layer at ∼ 70 m enhanced in iodocarbons. Mean surface (5–10 m) water concentrations of halocarbons in these coastal Antarctic waters were 57 pmol l− 1 CHBr3 (range 44–78 pmol l− 1), 4.2 pmol l− 1 CH2I2 (range 1.7–8.2 pmol l− 1), 0.8 pmol l− 1 CH2IBr (range 0.2–1.4 pmol l− 1), and 0.7 pmol l− 1 CH2ICl (range 0.2–2.4 pmol l− 1). Concurrent measurements in air suggested a sea-air flux of bromoform near the Antarctic coast of between 1 and 100 (mean 32.3, median 10.4) nmol m− 2 day− 1 and saturation anomalies of 557–1082% (mean 783%, median 733%), similar in magnitude to global shelf values. In surface samples affected by meltwater, CH2I2 fluxes ranged from 0.02 to 6.1 nmol m− 2 day− 1, with mean and median values of 1.9 and 1.1 nmol m− 2 day− 1, respectively.
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  • 84
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    Humus accumulation and microbial activities in calcari-epigleyic fluvisols under grassland and forest diked in for 30 years (2005)
    Elsevier
    In:  Soil Biology & Biochemistry, 37 (11). pp. 2163-2166.
    Details
    Publication Date: 2020-01-01
    Description: The accumulation and transformation of organic matter during soil development is rarely investigated although such processes are relevant when discussing about carbon sequestration in soil. Here, we investigated soils under grassland and forest close to the North Sea that began its genesis under terrestrial conditions 30 years ago after dikes were closed. Organic C contents of up to 99 mg g−1 soil were found until 6 cm soil depth. The humus consisted mainly of the fraction lighter than 1.6 g cm−3 which refers to poorly degraded organic carbon. High microbial respiratory activity was determined with values between 1.57 and 1.17 μg CO2–C g−1 soil h−1 at 22 °C and 40 to 70% water-holding capacity for the grassland and forest topsoils, respectively. The microbial C to organic C ratio showed values up to 20 mg Cmic g−1 Corg. Although up to 2.69 kg C m−2 were estimated to be sequestered during 30 years, the microbial indicators showed intensive colonisation and high transformation rates under both forest and grassland which were higher than those determined in agricultural and forest topsoils in Northern Germany.
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  • 85
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    Classification of the Alaskan Beaufort Sea Coast and estimation of carbon and sediment inputs from coastal erosion (2005)
    Springer
    In:  Geo-Marine Letters, 25 (2-3). pp. 69-80.
    Details
    Publication Date: 2015-02-11
    Description: A regional classification of shoreline segments along the Alaskan Beaufort Sea Coast was developed as the basis for quantifying coastal morphology, lithology, and carbon and mineral sediment fluxes. We delineated 48 mainland segments totaling 1,957 km, as well as 1,334 km of spits and islands. Mainland coasts were grouped into five broad classes: exposed bluffs (313 km), bays and inlets (235 km), lagoons with barrier islands (546 km), tapped basins (171 km) and deltas (691 km). Sediments are mostly silts and sands, with occasional gravel, and bank heights generally are low (2–4 m), especially for deltas (〈1 m). Mean annual erosion rates (MAER) by coastline type vary from 0.7 m/year (maximum 10.4 m/year) for lagoons to 2.4 m/year for exposed bluffs (maximum 16.7 m/year). MAERs are much higher in silty soils (3.2 m/year) than in sandy (1.2 m/year) to gravelly (−0.3 m/year) soils. Soil organic carbon along eroding shorelines (deltas excluded) range from 12 to 153 kg/m2 of bank surface down to the water line. We assume carbon flux out from depositional delta sediments is negligible. Across the entire Alaskan Beaufort Sea Coast, estimated annual carbon input from eroding shorelines ranges from –47 to 818 Mg/km/year (Metric tones/km/year) across the 48 segments, average 149 Mg/km/year (for 34 nondeltaic segments), and total 1.8×105 Mg/year. Annual mineral input from eroding shorelines ranges from −1,863 (accreting) to 15,752 Mg/km/year, average 2,743 Mg/km/year, and totals 3.3 ×106 Mg/year.
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  • 86
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    The use of CORONA images in remote sensing of periglacial geomorphology: an illustration from the NE Siberian coast (2005)
    Wiley
    In:  Permafrost and Periglacial Processes, 16 (2). pp. 163-172.
    Details
    Publication Date: 2015-02-06
    Description: CORONA images have been used for the mapping of periglacial features on the Bykovsky Peninsula and adjacent Khorogor Valley in northeast Siberia. Features, mapped and analysed within a geographical information system, include thermokarst depressions, thermo-erosional valleys, thermo-erosional cirques, thermokarst lakes, thermokarst lagoons and pingos. More than 50% of the area is strongly influenced by thermally-induced subsidence. Thermokarst in the area is probably less active today than in the early-middle Holocene.
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  • 87
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    Abundance, distribution and potential activity of methane oxidizing bacteria in permafrost soils from the Lena Delta, Siberia (2007)
    Wiley
    In:  Environmental Microbiology, 9 (1). pp. 107-117.
    Details
    Publication Date: 2018-01-01
    Description: The methane oxidation potential of active layer profiles of permafrost soils from the Lena Delta, Siberia, was studied with regard to its respond to temperature, and abundance and distribution of type I and type II methanotrophs. Our results indicate vertical shifts within the optimal methane oxidation temperature and within the distribution of type I and type II methanotrophs. In the upper active layer, maximum methane oxidation potentials were detected at 21°C. Deep active layer zones that are constantly exposed to temperatures below 2°C showed a maximum potential to oxidize methane at 4°C. Our results indicate a dominance of psychrophilic methanotrophs close to the permafrost table. Type I methanotrophs dominated throughout the active layer profiles but their number strongly fluctuated with depth. In contrast, type II methanotrophs were constantly abundant through the whole active layer and displaced type I methanotrophs close to the permafrost table. No correlation between in situ temperatures and the distribution of type I and type II methanotrophs was found. However, the distribution of type I and type II methanotrophs correlated significantly with in situ methane concentrations. Beside vertical fluctuations, the abundance of methane oxidizers also fluctuated according to different geomorphic units. Similar methanotroph cell counts were detected in samples of a flood plain and a polygon rim, whereas cell counts in samples of a polygon centre were up to 100 times lower.
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  • 88
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    Coastal dynamics at the Barents and Kara Sea key sites (2005)
    Springer
    In:  Geo-Marine Letters, 25 (2-3). pp. 110-120.
    Details
    Publication Date: 2015-03-05
    Description: The results of permafrost and coastal dynamics investigations at four key sites on the shores of the Kara and Barents Seas are discussed. Three ACD key sites, Marre-Sale, Shpindler, and Kolguev, characterize areas with active thermal erosion; key site Cape Bolvansky is found on a relatively stable coast. It is found that the coastal retreat rate has spatial and temporal variability, which is typical of the entire Arctic coast. Coastal deposits on the Kara and Barents Seas have a low organic carbon content. Annual input of material into the Kara Sea resulting from coastal degradation reaches 35–40 million t, including about 7.5 million t of ice, 0.35 million t of organic carbon, and 0.3 million t of soluble salts.
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  • 89
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    Freshwater ostracodes in Quaternary permafrost deposits in the Siberian Arctic (2005)
    Springer
    In:  Journal of Paleolimnology, 34 (3). pp. 363-376.
    Details
    Publication Date: 2015-04-02
    Description: Ostracode analysis was carried out on samples from ice-rich permafrost deposits obtained on the Bykovsky Peninsula (Laptev Sea). A composite profile was investigated that covers most of a 38-m thick permafrost sequence and corresponds to the last ca. 60 kyr of the Late Quaternary. The ostracode assemblages are similar to those known from European Quaternary lake deposits during cold stages. The ostracode habitats were small, shallow, cold, oligotrophic pools located in low centred ice wedge polygons or in small thermokarst depressions. In total, 15 taxa, representing 7 genera, were identified from 65 samples. The studied section is subdivided into six ostracode zones that correspond to Late Quaternary climatic and environmental stadial-interstadial variations established by other paleoenvironmental proxies: (1) cold and dry Zyrianian stadial (58–53 kyr BP); (2) warm and dry Karginian interstadial (48–34 kyr BP); (3) transition from the Karginian interstadial to the cold and dry Sartanian stadial (34–21 kyr BP); (4) transition from the Sartanian stadial to the warm and dry Late Pleistocene period, the Allerød (21–14 kyr BP); (5) transition from the Allerød to the warm and wet Middle Holocene (14–7 kyr BP); and (6) cool and wet Late Holocene (ca. 3 kyr BP). The abundance and diversity of the ostracodes will be used as an additional bioindicator for paleoenvironmental reconstructions of the Siberian Arctic.
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  • 90
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    Methanogenic activity and biomass in Holocene permafrost deposits of the Lena Delta, Siberian Arctic and its implication for the global methane budget (2007)
    Wiley
    In:  Global Change Biology, 13 (5). pp. 1089-1099.
    Details
    Publication Date: 2017-12-31
    Description: Permafrost environments within the Siberian Arctic are natural sources of the climate relevant trace gas methane. In order to improve our understanding of the present and future carbon dynamics in high latitudes, we studied the methane concentration, the quantity and quality of organic matter, and the activity and biomass of the methanogenic community in permafrost deposits. For these investigations a permafrost core of Holocene age was drilled in the Lena Delta (72°22′N, 126°28′E). The organic carbon of the permafrost sediments varied between 0.6% and 4.9% and was characterized by an increasing humification index with permafrost depth. A high CH4 concentration was found in the upper 4 m of the deposits, which correlates well with the methanogenic activity and archaeal biomass (expressed as PLEL concentration). Even the incubation of core material at −3 and −6°C with and without substrates showed a significant CH4 production (range: 0.04–0.78 nmol CH4 h−1 g−1). The results indicated that the methane in Holocene permafrost deposits of the Lena Delta originated from modern methanogenesis by cold-adapted methanogenic archaea. Microbial generated methane in permafrost sediments is so far an underestimated factor for the future climate development.
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  • 91
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    Excess of bottom-released methane in an Arctic shelf sea polynya in winter (2007)
    Elsevier
    In:  Continental Shelf Research, 27 (12). pp. 1692-1701.
    Details
    Publication Date: 2017-12-31
    Description: Latent heat polynyas are regions generating strong ice formation, convection and extensive water mass formation. Here we report on the effects of these processes on resuspension of sediments and subsequent methane release from the seafloor and on the resulting excess methane concentration in surface water on a polar shelf during winter. The study is based on measurements of concentration and δ13C values of methane, water temperature, salinity, light transmission and sea ice data collected in March 2003 in Storfjorden, southern Svalbard. In winter, strong and persistent northeasterly winds create polynyas in eastern Storfjorden and cause ice formation. The resulting brine-enriched water cascades from the Storfjordbanken into the central depression thereby enhancing the turbulence near the seafloor. A distinct benthic nepheloid layer was observed reflecting the resuspension of sediments by the cascading dense bottom water. High concentrations of 13C-depleted methane suggest submarine discharge of methane with the resuspended sediments. As the source of the submarine methane, we propose recent bacterial methanogenesis near the sediment surface because of extremely high accumulation rates of organic carbon in Storfjorden. Convective mixing transports newly released methane from the bottom to the sea surface. This eventually results in an excess concentration in surface water with respect to the atmospheric equilibrium, and a sea-air flux of methane during periods of open water. When a new ice cover is formed, methane becomes trapped in the water column and subsequently oxidized. Thus, the residual methane is strongly enriched in 13C in relation to the δ13CCH4δ13CCH4 signature of atmospheric methane. Our results show that latent heat polynyas may induce a direct pathway for biogases like methane from sediments to the atmosphere through coupling of biogeochemical and oceanographic processes. Extrapolating these processes to all Arctic ocean polynyas, we estimate a transfer of CH4 between 0.005 and 0.02 Tg yr−1. This is not a large contribution but the fluxes from the polynyas are 20–200 times larger than the ocean average and the methane evasion process in polynyas is certainly one that can be altered under climate change.
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  • 92
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    Organic matter quality and supply to deep-water coral/mound systems of the NW European Continental Margin (2007)
    Springer
    In:  International Journal of Earth Sciences, 96 (1). pp. 159-170.
    Details
    Publication Date: 2015-09-21
    Description: Comparison of five deep-water coral (DWC)/mound ecosystems along the European Continental Margin shows that suspended particulate organic matter (sPOM), a potential food source, is lipid rich and of high quality. However, there are differences between the sites. The Darwin and Pelagia Mounds (N. Rockall Trough and N. Porcupine Bank, respectively) have higher proportions of labile particulate lipids (including high proportions of polyunsaturated fatty acids) in the benthic boundary layer than Logachev, Hovland and Belgica Mounds (Rockall Bank, S. Porcupine Bank and Porcupine Seabight, respectively). The high quality sPOM could be transported downslope from the euphotic zone. There is some evidence for inter-annual variability at some sites (e.g. Hovland and Logachev Mounds) as large differences in suspended lipid and particulate organic carbon concentrations were observed over the sampling period. Elevated total organic carbon contents of sediments at mound sites, relative to control sites in some cases (particularly Darwin Mounds), probably reflect local hydrodynamic control and the trapping of sPOM by the DWC. Fresh POM can be relatively rapidly transferred to significant depth (up to 8 cm) through bioturbation that is evident at all sites. There is no clear evidence of present day hydrocarbon seepage at any of the sites.
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  • 93
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    Bioerosion patterns in a deep-water Lophelia pertusa (Scleractinia) thicket (Propeller Mound, northern Porcupine Seabight) (2005)
    Springer
    In:  In: Cold-Water Corals and Ecosystems. , ed. by Freiwald, A. and Roberts, J. M. Springer, Berlin, pp. 915-936. ISBN 978-3-540-24136-2
    Details
    Publication Date: 2015-09-30
    Description: This study focuses on bioerosion of an aphotic deep-water coral mound, the Propeller Mound, in the northern Porcupine Seabight. The predominant framework builder is the cosmopolitan cold-water coral Lophelia pertusa. We demonstrate bioerosion patterns within the skeleton of L. pertusa using a new embedding method under vacuum conditions with subsequent scanning electron microscope analysis. Following this method, 23 ichnospecies are documented and related to heterotrophic organism groups such as Bacteria (1), Fungi (12), Bryozoa (1), Foraminifera (3), and Porifera (6). Predominant endolithic sponges in the framework of L. pertusa are Alectona millari and Spiroxya heteroclita. Owing to its characteristic growth and surface ornamentation, trace casts of Spiroxya heteroclita are correlated to the well-known trace fossil Entobia laquea. Investigations of thin sections of post-mortem skeletons show a clearly pronounced endolithic tiering of three penetration depths. The analysed samples are divided into three macroscopic preservational stages differing in post-mortem age, and exposure of the framework. Bioerosion affects bare parts of the coral skeleton. Bioeroders preferably settle on one side of an upright growing colony. A succession usually starts with the infestation by bacteria and fungi. Contact zones of epiliths are preferred areas for penetration by endoliths. Sponges and foraminifers appear 10 cm below the zone of living polyps, followed by boring bryozoans 15 cm below. However, in one case the sponge Spiroxya heteroclita is documented in the skeleton of living polyps. Frameworks exposed to water host 19 ichnospecies, thus forming the most diverse ichnocoenosis, whereas nine ichnospecies are documented in coral specimens buried by sediment. Mapping of epi- and endoliths in living and freshly necrotic colonies represents a useful tool for monitoring environmental conditions and define ecological “health” of deep-water corals in a rapid large-scale assessment of the state of coral reefs.
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  • 94
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    U/Th-dating of deep-water corals from the eastern North Atlantic and the western Mediterranean Sea (2005)
    Springer
    In:  In: Cold-Water Corals and Ecosystems. , ed. by Freiwald, A. and Roberts, J. M. Springer, Berlin, pp. 157-172.
    Details
    Publication Date: 2015-09-30
    Description: Deep-water corals are widespread in the North Atlantic. Colonial azooxanthellate scleractinians sustain ecosystems mostly in the bathyal zone down the slopes and oceanic banks off the Iberian Peninsula to as far north as the Scandinavian shelf off northern Norway. Estimates of the geological age of 37 deepwater corals exposed at the seabed from major reef areas in the North Atlantic were based on U/Th datings. In contrast to the purely Holocene ages of deep-water corals in Scandinavian waters, the Faroe area and the Rockall Trough, deep-water corals from lower latitudes like the seamounts off NW-Africa, the Mid-Atlantic Ridge and the western Mediterranean Sea seemed to have grown continuously over the last 50 ka. Overall, deep-water corals showed U/Th ages between 0.09 and 53.5 ka.
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  • 95
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    Calcifying extracellular mucus substances (EMS) of Madrepora oculata – a first geobiological approach (2005)
    Springer
    In:  In: Cold-Water Corals and Ecosystems. , ed. by Freiwald, A. and Roberts, J. M. Springer, Berlin, pp. 731-744. ISBN 978-3-540-24136-2
    Details
    Publication Date: 2017-02-02
    Description: Colonial non-zooxanthellate corals from deep-water coral reefs, Lophelia pertusa and Madrepora oculata, produce large amounts of extracellular mucus (EMS). This mucus has various functions, e.g., an antifouling capability protecting the coral skeleton from attacks of endolithic and boring organisms. Both corals show thick epithecal and exothecal skeletal parts with a clear lamellar growth pattern. The formation of the epitheca is unclear. It is supposed that the EMS play a central role during the calcification process of the epithecal skeletal parts. Staining with the fluorochrome tetracycline has shown an enrichment of Ca2+ ions in the mucus. In order to investigate this hypothesis, the protein content of the mucus and the intracrystalline organic matter from newly formed epithecal aragonite of Madrepora oculata was determined via sodium dodecyl sulfate (SDS) gel electrophoresis. Identical band patterns within both substances could be detected, one around 45 kDa molecular weight and a cluster around 30-35 kDa molecular weight. The occurrence of identical protein patterns within the mucus and in the newly formed aragonite confirms the idea that the mucus plays an important role during the organomineralization of the coral epitheca.
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  • 96
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    Spatial and temporal structure of the Denmark Strait Overflow revealed by acoustic observations (2007)
    Springer
    In:  Ocean Dynamics, 57 (2). pp. 75-89.
    Details
    Publication Date: 2017-02-07
    Description: In spite of the fundamental role the Atlantic Meridional Overturning Circulation (AMOC) plays for global climate stability, no direct current measurement of the Denmark Strait Overflow, which is the densest part of the AMOC, has been available until recently that resolve the cross-stream structure at the sill for long periods. Since 1999, an array of bottom-mounted acoustic instruments measuring current velocity and bottom-to-surface acoustic travel times was deployed at the sill. Here, the optimization of the array configuration based on a numerical overflow model is discussed. The simulation proves that more than 80% of the dense water transport variability is captured by two to three acoustic current profilers (ADCPs). The results are compared with time series from ADCPs and Inverted Echo Sounders deployed from 1999 to 2003, confirming that the dense overflow plume can be reliably measured by bottom-mounted instruments and that the overflow is largely geostrophically balanced at the sill.
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  • 97
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    Early history of the eastern Sibao Orogen (South China) during the assembly of Rodinia: New mica 40Ar/39Ar dating and SHRIMP U–Pb detrital zircon provenance constraints (2007)
    Elsevier
    In:  Precambrian Research, 159 (1-2). pp. 79-94.
    Details
    Publication Date: 2015-11-24
    Description: The Sibao Orogen in South China is one of the poorest known Grenville-aged orogenic belts through which the Neoproterozoic supercontinent Rodinia assembled. We report here the first UV laser spot 40Ar/39Ar mica and SHRIMP U–Pb zircon ages from a rare Grenville-aged metamorphic complex, the Tianli Schists, in the eastern Sibao Orogen. Our U–Pb zircon provenance ages indicate that the protolith of the Tianli Schists was a clastic sedimentary succession most likely derived from the Yangtze Block. The depositional age of the protolith is younger than 1530 Ma, as constrained by the youngest detrital zircon grains, but is older than 1040 Ma as constrained by the oldest 40Ar/39Ar muscovite ages. The Yangtze Block provenance for the Tianli Schists suggests that the Sibaoan ophiolitic complexes in northeastern Jiangxi, the ca. 970 Ma Xiwan adakitic granite intrusions, and the ca. 900 Ma(?) Xiwan blueschists, all to the northwest of the study region, were likely formed during the closure of a back-arc basin along the margin of the Yangtze Block. Our in situ UV laser 40Ar/39Ar results from S1 and S2 muscovites suggest that the Tianli Schists underwent metamorphism and deformation at 1042 ± 7 Ma to 1015 ± 4 Ma, the oldest known metamorphic event in the eastern Sibao Orogen. Muscovite/biotite cooling ages of ca. 968 ± 4 and 942 ± 8 Ma are recorded by deformed and recrystallised muscovite and biotite, respectively, indicating tectonic reactivation before 900 Ma, during the later stages of the Sibao Orogeny. Together with previous results from the western Sibao Orogen, our work suggests that the closure of the ocean between the Yangtze and Cathaysia Blocks during the assembly of Rodinia was diachronous: ≥1000 Ma at the western Sibao Orogen and ca. 900 Ma at the eastern Sibao Orogen.
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  • 98
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    Unknown
    Annonaceous acetogenin mimics bearing a terminal lactam and their cytotoxicity against cancer cells (2007)
    Elsevier
    In:  Bioorganic & Medicinal Chemistry Letters, 17 (12). pp. 3426-3430.
    Details
    Publication Date: 2016-01-11
    Description: Annonaceous acetogenins are a large class of naturally occurring polyketides exhibiting potent anticancer activities. Based on our previous discovery of AA005, a multi-ether mimic of natural acetogenins having potent antitumor activities and significant selectivity between normal cells and cancer cells, a new series of mimics containing a terminal lactam were designed, synthesized and evaluated. Bioactivity study against cancer cells shows that the N-methylated lactam-containing compounds 3, 4, and 5 exhibit comparable potencies to that of AA005, as well as the similar selectivity to cancer cells. Hydrocarbon-length effects of N-alkyl were further explored through synthesizing derivatives 24–26, and application of this derivation protocol to the fluorescent labeling was also investigated.
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  • 99
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    A 12-year study of the seasonal and interannual dynamics of mesozooplankton in the Laptev Sea: Significance of salinity regime and life cycle patterns (2005)
    Elsevier
    In:  Global and Planetary Change, 48 (1-3). pp. 141-164.
    Details
    Publication Date: 2016-02-12
    Description: Over a 12-year period (1989–2000) the spatial and temporal distribution of zooplankton in the Laptev Sea (Arctic Siberia) has been investigated. A total number of 111 taxa from 10 phyla were found. Sixteen species are reported from this region for the first time. The distribution and abundance of zooplankton on the Laptev Sea shelf is dependent on the main direction of river water spread, which varies between years. While the western and northeastern Laptev Sea shelf is dominated by a marine–neritic fauna, the central part is inhabited by a transitional brackish–marine assemblage. A brackish–neritic community characterizes the eastern and southeastern regions, where lowest salinities usually prevail. Closer to estuaries the summer zooplankton consists of both freshwater and brackish-water species, whereas in winter brackish-water species are dominant. Average zooplankton abundance varies seasonally and interannually, particularly in the southeastern Laptev Sea. The amplitude of these variations mainly depends on the state of the populations of the most common Copepoda species, the intensity of their reproduction, and their success in overwintering. Two seasonal abundance maxima were found, at the end of winter and at the end of summer. During the period of highest reproduction in summer the abundance may be 50 times greater than during overwintering. The average population abundance can vary by the factor of 2 in summer and in winter from year to year.
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  • 100
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    Palaeobotanical evidence for warm summers in the East Siberian Arctic during the last cold stage (2005)
    Elsevier
    In:  Quaternary Research, 63 (3). pp. 283-300.
    Details
    Publication Date: 2015-02-12
    Description: Plant macrofossils from the “Mamontovy Khayata” permafrost sequence (71°60′N, 129°25′E) on the Bykovsky Peninsula reflect climate and plant biodiversity in west Beringia during the last cold stage. 70 AMS and 20 conventional 14C dates suggest sediment accumulation between about 60,000 and 7500 14C yr B.P. The plant remains prove that during the last cold-stage arctic species (Minuartia arctica, Draba spp., Kobresia myosuroides) coexisted with aquatic (Potamogeton vaginatus, Callitriche hermaphroditica), littoral (Ranunculus reptans, Rumex maritimus), meadow (Hordeum brevisubulatum, Puccinellia tenuiflora) and steppe taxa (Alyssum obovatum, Silene repens, Koeleria cristata, Linum perenne). The reconstructed vegetation composition is similar to modern vegetation mosaics in central and northeast Yakutian relict steppe areas. Thus, productive meadow and steppe communities played an important role in the Siberian Arctic vegetation during the late Pleistocene and could have served as food resource for large populations of herbivores. The floristic composition reflects an extremely continental, arid climate with winters colder and summers distinctly warmer than at present. Holocene macrofossil assemblages indicate a successive paludification possibly connected with marine transgression, increased oceanic influence and atmospheric humidity. Although some steppe taxa were still present in the early Holocene, they disappeared completely before ∼2900 14C yr B.P.
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