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  • Weitere Quellen  (632)
  • Springer  (473)
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  • 1980-1984  (75)
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  • 1
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    A comparative study of the diagenesis in diapir-influenced reef atolls and a fault block reef platform in the Late Albian of the Vasco-Cantabrian Basin (2018)
    Springer | Berlin [u.a.]
    Details
    Publikationsdatum: 2021-04-25
    Schlagwort(e): 551 ; VKB 350 ; 38.20
    Sprache: Englisch
    Materialart: anthologyArticle , publishedVersion
    Format: 186-209
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    CITATION GEO-LEO
  • 2
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    Calcifying extracellular mucus substances (EMS) of Madrepora oculata (2018)
    Springer | Berlin [u.a.]
    Details
    Publikationsdatum: 2021-04-25
    Beschreibung: 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.
    Schlagwort(e): 551 ; VU 000 ; 38.20
    Sprache: Englisch
    Materialart: anthologyArticle , publishedVersion
    Format: 731-744
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    CITATION GEO-LEO
  • 3
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    Hydrogen incorporation in enstatite in the system MgO-SiO2-H2O-NaCl (2018)
    Springer
    Details
    Publikationsdatum: 2021-03-29
    Beschreibung: The incorporation of hydrogen in enstatite in a hydrous system containing various amounts of NaCl was investigated at 25 kbar. The hydrogen content in enstatite shows a clear negative correlation to the NaCl-concentration in the system. The most favourable explanation is the reduction of water fugacity due to dilution. Other reasons for the limited hydrogen incorporation at high NaCl levels, such as a significant influence of Na+ on the defect chemistry or an exchange between OH- and Cl-in enstatite, appear much less important. A partition coefficient D Na En/Fluid = 0.0013 could be determined, demonstrating that Na is less incompatible in enstatite than H. The new results support the idea that dissolved components have to be considered when the total hydrogen storage capacity in nominally anhydrous minerals is estimated, especially in geological settings with high levels of halogens, such as subduction zones.
    Schlagwort(e): KEnstatite; Hydrogen incorporation;Water activity; Sodium; Chlorine ; 551
    Sprache: Englisch
    Materialart: article , publishedVersion
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  • 4
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    Mechanism of uranium fixation by zero valent iron: the importance of co-precipitation (2018)
    Springer | Berlin
    Details
    Publikationsdatum: 2021-03-29
    Beschreibung: The coprecipitation of U (VI) with iron corrosion products from aqueous solutions by zero valent iron was investigated. The evidence of coprecipitation was demonstrated by conducting experiments with well characterized scrap iron,pyrite and a mixture of both materials with experimental durations of up to four months. Results indicate that under anoxic conditions only less than one tenth of the immobilized U(VI) was associated with the surface of scrap iron, whereas theremaining amount is entrapped in aging corrosion products.
    Schlagwort(e): 551
    Sprache: Englisch
    Materialart: anthologyArticle , acceptedVersion
    Format: 577-586
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  • 5
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    The behaviour of consolidated volcanic tuffs: weathering mechanisms under simulated laboratory conditions (2018)
    Springer
    Details
    Publikationsdatum: 2021-03-29
    Beschreibung: Five volcanic tuffs ranging from dacitic tuffs of Hungary to rhyolite, phonolite and basaltic tuffs of Germany were consolidated under laboratory conditions. Prior to consolidation an anti-hygro, a hydrous consolidant, which reduces the swelling ability of clay minerals, was applied. The three consolidants, a silicic acid ester (SAE), an elastic silicic acid ester (eSAE) and an acrylate resin (PMMA) were applied on test specimens under vacuum. Petrographic characterisation (polarizing microscopy, XRD, SEM) provided data for fabric analyses and the mineral composition of the tuffs. Changes in fabric, effective porosity, density, tensile strength, ultrasonic wave velocity were evaluated after the treatment. Weathering simulation tests such as hygric dilatation and thermal dilatation aimed to prove the effectiveness of consolidation and the durability of consolidated tuff samples. More than 500 samples were analysed. The tests showed that SAE caused the highest increase in indirect tensile strength. The water absorption and the pore size distribution of the tuffs were modified by consolidation. The PMMA reduced the water absorption the most, whereas SAE modified it the least. All the tested consolidants increased the thermal dilatation of the tuffs. The changes in hygric dilatation were not uniform: for most tuffs SAE increased and PMMA decreased the hygric dilatation, although the clay-rich Habichtswald tuff showed the opposite trend. The changes in hygric and thermal behaviour of consolidated tuff require special care when specific consolidants are chosen. These products modify the physical properties of consolidated tuffs and change the behaviour of weathering.
    Schlagwort(e): Strengthening agents; Tuff; Silicic acid ester; PMMA; Durability ; 551
    Sprache: Englisch
    Materialart: article , publishedVersion
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  • 6
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    Seasonal variability of Holocene climate: a palaeolimnological study on varved sediments in Lake Jues (Harz Mountains, Germany) (2018)
    Springer | Springer
    Details
    Publikationsdatum: 2021-03-29
    Schlagwort(e): Albrecht-von-Haller-Institut für Pflanzenwissenschaften / Abteilung für Palynologie und Klimadynamik ; Palaeolimnology; Holocene climate; Diatoms; Green algae; Pollen; Karst ; 551
    Sprache: Englisch
    Materialart: article , publishedVersion
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  • 7
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    Characterizing uranium solubilization under natural near oxic conditions (2018)
    Springer | Berlin/Heidelberg
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    Publikationsdatum: 2021-03-29
    Beschreibung: A 782 d solubilization study using not shaken batch experiments and involving one uranium-bearing rock and three natural carbonate minerals was conducted to characterize uranium (U) leaching under oxic conditions. Results showed that aqueous U concentration increased continuously with a solubilization rate of 0.16 mgm-2h-1 for the first 564 d (1.5 y). After 1.5 y, U concentration reached a maximum value (saturation) and decreased afterwards. The saturation concentration of 54 mgL-1 (mean value) was influenced to various extent by the presence of carbonate minerals. Dissolution/precipitation, adsorption or ion exchange processes appear to control U solubilization.
    Schlagwort(e): 551
    Sprache: Englisch
    Materialart: anthologyArticle , acceptedVersion
    Format: 425-435
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    CITATION GEO-LEO
  • 8
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    Phylogenetic aspects and new descriptions of Spicule-Bearing, Hadromerid Sponges with a secondary calcareous skeleton (Tetractinomorpha, Demospongiae) (2018)
    Springer | Berlin [u.a.]
    Details
    Publikationsdatum: 2021-04-25
    Schlagwort(e): 551 ; VU 000 ; 38.20
    Sprache: Englisch
    Materialart: anthologyArticle , publishedVersion
    Format: 179-211
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  • 9
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    The fossil record of the Haplosclerid excavating sponge Aka de Laubenfels (2018)
    Springer | Berlin [u.a.]
    Details
    Publikationsdatum: 2021-04-25
    Schlagwort(e): 551 ; VU 000 ; 38.20
    Sprache: Englisch
    Materialart: anthologyArticle , publishedVersion
    Format: 102-120
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  • 10
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    Renewed study of the type material of Palaeospongilla chubutensis Ott and Volkheimer (1972) (2018)
    Springer | Berlin [u.a.]
    Details
    Publikationsdatum: 2021-04-25
    Schlagwort(e): 551 ; VU 000 ; 38.20
    Sprache: Englisch
    Materialart: anthologyArticle , publishedVersion
    Format: 121-133
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  • 11
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    Marble bowing: comparative studies of three different public building facades (2018)
    Springer
    Details
    Publikationsdatum: 2021-03-29
    Beschreibung: The veneer cladding of the Oeconomicum (OEC, Göttingen), the State Theatre of Darmstadt (STD, Darmstadt) and of the State and University Library (SUB, Göttingen) is characterised by pronounced bowing after a short time of exposure. Direct comparison of bowing data related to measurements from 2000 to 2003 at the SUB clearly show that the amplitude in bowing had significantly increased. The bowing is different in intensity and orientation (concave, convex). The cladding material (Peccia marble, Rosa Estremoz marble and Carrara marble) are different in lattice preferred orientation, grain size distribution and grain interlocking. Depending on the bowing, panels may show cracks mostly initiated at the dowels. The percentage of visible cracks and breakouts increases with the amplitude of bowing except for the STD. Repetitive heatingcooling under dry conditions leads to considerable inelastic residual strain only after the first or second thermal cycle. The residual strain continuously increases again if water is present, whereby the moisture content after a thermal cycle has a certain impact on the decay rate. The water-enhanced thermal dilatation strongly correlates with the deterioration rate obtained from the laboratory bow test. Detailed petrophysical investigations provide evidence that with increasing bowing a decrease of mechanical properties (flexural strength or breaking load at dowel hole) occur. Marble degradation is also connected with the increase in porosity and a general shift of the maximum pore radii to larger pore sizes...
    Schlagwort(e): Bowing; Marble; Building mapping;Residual strain;Thermal expansion; Bowing potential ; 551
    Sprache: Englisch
    Materialart: article , publishedVersion
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  • 12
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    Physical Properties of Rocks (1982)
    Springer
    In:  Berlin, Springer, vol. V/1, subvol. a, pp. 559-932, (ISBN 0-935702-96-2)
    Details
    Publikationsdatum: 1982
    Schlagwort(e): Rock mechanics ; Physical properties of rocks ; Handbook of geophysics ; Laboratory measurements ; density ; porosity ; elasticity ; electrical ; magnetic ; properties ; radioactivity ; moon ; ice ; Czermak ; Huckenholz ; Rybach ; Schmid ; Schopper ; Schuch ; Stoeffler ; Wohlenberg
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    BIBLIOGRAFIE SEISMOLOGIE
  • 13
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    Condensed Matter; Magnetic Properties. Magnetic and Other Properties of Oxides and Related Compounds (1970)
    Springer
    In:  Berlin, Springer, vol. III/4, Part a, no. XVI:, pp. 1-14, (ISBN 0-87590-299-5 (soft cover))
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    Publikationsdatum: 1970
    Schlagwort(e): Handbook of geophysics ; Handbook of physics ; Handbook of mineralogy
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    BIBLIOGRAFIE SEISMOLOGIE
  • 14
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    Group III: Crystals and Solid State Physics. Vol. 5, Part a: Geophysics and Spaceresearch (1982)
    Springer
    In:  Berlin, Springer, vol. III/12, Supplement to III/4, no. XVI:, pp. 1-14, (ISBN 0-87590-299-5 (soft cover))
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    Publikationsdatum: 1982
    Schlagwort(e): Handbook of geophysics ; Handbook of physics ; Handbook of mineralogy
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    BIBLIOGRAFIE SEISMOLOGIE
  • 15
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    Seismic Wave Propagation in Stratified Media (1983)
    Cambridge University Press
    In:  Cambridge, 342 pp., Cambridge University Press, vol. 13, no. XVI:, pp. 227-235, (ISBN 3-540-43528-X)
    Details
    Publikationsdatum: 1983
    Schlagwort(e): Textbook of geophysics ; Seismology ; Seismics (controlled source seismology) ; Waves
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    BIBLIOGRAFIE SEISMOLOGIE
  • 16
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    Seismic Waves and Sources (1981)
    Springer
    In:  New York, 1108 pp., Springer, vol. 96, pp. 225, (ISBN 0-471-95596-5)
    Details
    Publikationsdatum: 1981
    Schlagwort(e): FROTH ; RUB ; GMG ; 3.15.80 ; Textbook of geophysics ; Seismology ; Waves ; Wavelet processing ; SModelling ; Dislocation ; Elasticity theory of dislocations ; Source
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    BIBLIOGRAFIE SEISMOLOGIE
  • 17
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    Geophysics of the Solid Earth, the Moon and the Planets (1984)
    Springer
    In:  Heidelberg, Springer, vol. V/2, no. Subvol. a, pp. 220, (ISBN: 0-08-037951-6)
    Details
    Publikationsdatum: 1984
    Schlagwort(e): Review article ; Seismology ; (The Earth's free) oscillations ; Waves ; Gravimetry, Gravitation ; Geomagnetics ; Planetology ; solar ; system ; Anderson ; Brosche ; Busse ; Dziewonski ; Groten ; von ; Herzen ; Jackson ; Janle ; Kahle ; Maelzer ; Meissner ; Mueller ; Prodehl ; Rybach ; Schneider ; Suendermann ; Waenke ; Wilhelm ; Zuern
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  • 18
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    Transmission of Information by Orthogonal Functions (1972)
    Springer
    In:  New York, Springer, vol. 113, no. XVI:, pp. 1-14, (ISBN 1-56670-263-3)
    Details
    Publikationsdatum: 1972
    Schlagwort(e): Transformations ; squ ; Textbook of informatics ; Textbook of mathematics
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    BIBLIOGRAFIE SEISMOLOGIE
  • 19
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    Condensed Matter; Magnetic Properties. Magnetic and Other Properties of Oxides and Related Compounds (1970)
    Springer
    In:  Berlin, Springer, vol. III/4, Part b, no. XVI:, pp. 1-14, (ISBN 0-87590-299-5 (soft cover))
    Details
    Publikationsdatum: 1970
    Schlagwort(e): Handbook of geophysics ; Handbook of physics ; Handbook of mineralogy
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    BIBLIOGRAFIE SEISMOLOGIE
  • 20
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    Exploration Seismology Vol. 1, History, Theory and Data Acquisition (1982)
    Cambridge University Press
    In:  Boston, 227 pp., Cambridge University Press, vol. Developments in Petroleum Science vol. 15B, no. Publ. No. 12, pp. 9, (ISBN 0-521-66023-8 hc (0-521-66953-7 pb))
    Details
    Publikationsdatum: 1982
    Schlagwort(e): Textbook of geophysics ; Seismics (controlled source seismology)
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  • 21
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    Matrizen und ihre Anwendungen, 5. überarbeitete u. erw. Aufl., Teil 1: Grundlagen (1984)
    Springer
    In:  Berlin, Springer, vol. 6, no. 1, pp. 1-40, (ISBN: 0-444-51340-X)
    Details
    Publikationsdatum: 1984
    Schlagwort(e): Textbook of mathematics ; lineare ; Algebra ; Inversion ; Eigen-value ; MINV ; Zurmuhl
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  • 22
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    Seismic waves and free oscillations (1984)
    Springer
    In:  Bull., Polar Proj. OP-O3A4, Physical Properties of Rocks, Heidelberg, Springer, vol. V/2, no. Subvol. a, pp. 61-83, (ISBN 0080419208)
    Details
    Publikationsdatum: 1984
    Schlagwort(e): Review article ; Seismology ; (The Earth's free) oscillations ; Waves ; Muller ; Zuern ; Zurn
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  • 23
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    Fracture and flow of rocks and minerals (1982)
    Springer
    In:  Bull., Open-File Rept., Zahlenwerte und Funktionen aus Naturwiss. und Technik, L.B. V-1b, Berlin, Springer, vol. 81A, no. 16, pp. 141-238, (ISBN 0080419208)
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    Publikationsdatum: 1982
    Schlagwort(e): Textbook of geophysics ; Fracture ; Rock mechanics ; Rheology
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  • 24
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    Group III: Crystals and Solid State Physics. Vol. 5, Part b: Physical Properties of Rocks (1982)
    Springer
    In:  Berlin, Springer, vol. III/12, Supplement to III/4, no. XVI:, pp. 1-14, (ISBN 0-87590-299-5 (soft cover))
    Details
    Publikationsdatum: 1982
    Schlagwort(e): Handbook of geophysics ; Handbook of physics ; Handbook of mineralogy
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    BIBLIOGRAFIE SEISMOLOGIE
  • 25
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    Model Seismology, Vol. 2, Data Processing and Interpretation (1971)
    Cambridge University Press
    In:  Cambridge, Cambridge University Press, vol. IUGG Volume 18, no. 85, pp. 175, (3-7723-6434-9)
    Details
    Publikationsdatum: 1971
    Schlagwort(e): Seismics (controlled source seismology) ; Textbook of geophysics ; SEModelling ; Data analysis / ~ processing
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  • 26
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    Exploration Seismology Vol. 2, Data-Processing and Interpretation (1983)
    Cambridge University Press
    In:  Boston, 227 pp., Cambridge University Press, vol. Developments in Petroleum Science vol. 15B, no. Publ. No. 12, pp. 9, (ISBN 0-521-66023-8 hc (0-521-66953-7 pb))
    Details
    Publikationsdatum: 1983
    Schlagwort(e): Textbook of geophysics ; Seismics (controlled source seismology)
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  • 27
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    Geschwindigkeiten elastischer Wellen und Elastizitätskonstanten von Gesteinen und gesteinsbildenden Mineralen (1982)
    Springer
    In:  Professional Paper, Physical Properties of Rocks, Berlin, Springer, vol. V/1, no. Subvol. b, pp. 1-96, (ISBN: 3-540-23712-7)
    Details
    Publikationsdatum: 1982
    Schlagwort(e): Velocity ; Elasticity ; Physical properties of rocks ; Handbook of geophysics
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  • 28
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    Physikalische Eigenschaften des Eises (1982)
    Springer
    In:  Bull., Polar Proj. OP-O3A4, Physical Properties of Rocks, Berlin, Springer, vol. V/1, no. Subvol. b, pp. 339-346, (ISBN 0080419208)
    Details
    Publikationsdatum: 1982
    Schlagwort(e): Rock mechanics ; glaciology ; Handbook of geophysics
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  • 29
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    Physical Properties of Rocks (1982)
    Springer
    In:  Berlin, Springer, vol. V/1, subvol. b, pp. 559-932, (ISBN 0-935702-96-2)
    Details
    Publikationsdatum: 1982
    Schlagwort(e): Rock mechanics ; Physical properties of rocks ; Handbook of geophysics ; Laboratory measurements ; density ; porosity ; elasticity ; electrical ; magnetic ; properties ; radioactivity ; moon ; ice ; Beblo ; Berktold ; Bleil ; Gebrande ; Grauert ; Haack ; Haak ; Kern ; Miller ; Petersen ; Pohl ; Rummel ; Schopper
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  • 30
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    Synergetics (1983)
    Springer
    In:  Berlin, Springer, vol. 167, no. XVI:, pp. 385-389, (ISBN 0-12-305355-2)
    Details
    Publikationsdatum: 1983
    Schlagwort(e): Artificial intelligence (AI) ; neu ; Textbook of physics
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  • 31
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    Condensed Matter; Magnetic Properties. Magnetic and Other Properties of Oxides and Related Compounds Part b: Spinels, Fe Oxides and Fe-Me-O Compounds (1980)
    Springer
    In:  Berlin, Springer, vol. III/12, Supplement to III/4, no. XVI:, pp. 1-14, (ISBN 0-87590-299-5 (soft cover))
    Details
    Publikationsdatum: 1980
    Schlagwort(e): Handbook of geophysics ; Handbook of physics ; Handbook of mineralogy
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  • 32
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    Piezoelektrische Meßtechnik (1980)
    Springer
    In:  Dordrecht, IX+266 pp., Springer, vol. 3, no. ALEX(01)-FR-77-01, AFTAC Contract F08606-76-C-0025, pp. 329, (ISBN 1-903544-06-8)
    Details
    Publikationsdatum: 1980
    Schlagwort(e): SEModelling ; Instruments ; Laboratory measurements
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  • 33
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    Internally heated pressure vessels (1971)
    Springer
    In:  Bull., Polar Proj. OP-O3A4, Research Techniques for High Pressure and High Temperature, New York, Springer, vol. 20, no. XVI:, pp. 217-250, (ISBN: 3-540-23712-7)
    Details
    Publikationsdatum: 1971
    Schlagwort(e): Textbook of physics ; Laboratory measurements ; Stress ; ERYBACKI
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  • 34
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    Key impacts of climate engineering on biodiversity and ecosystems, with priorities for future research (2016)
    Taylor & Francis
    In:  Journal of Integrative Environmental Sciences, 13 (2-4). pp. 103-128.
    Details
    Publikationsdatum: 2021-04-23
    Beschreibung: Climate change has significant implications for biodiversity and ecosystems. With slow progress towards reducing greenhouse gas emissions, climate engineering (or ‘geoengineering’) is receiving increasing attention for its potential to limit anthropogenic climate change and its damaging effects. Proposed techniques, such as ocean fertilization for carbon dioxide removal or stratospheric sulfate injections to reduce incoming solar radiation, would significantly alter atmospheric, terrestrial and marine environments, yet potential side-effects of their implementation for ecosystems and biodiversity have received little attention. A literature review was carried out to identify details of the potential ecological effects of climate engineering techniques. A group of biodiversity and environmental change researchers then employed a modified Delphi expert consultation technique to evaluate this evidence and prioritize the effects based on the relative importance of, and scientific understanding about, their biodiversity and ecosystem consequences. The key issues and knowledge gaps are used to shape a discussion of the biodiversity and ecosystem implications of climate engineering, including novel climatic conditions, alterations to marine systems and substantial terrestrial habitat change. This review highlights several current research priorities in which the climate engineering context is crucial to consider, as well as identifying some novel topics for ecological investigation.
    Materialart: Article , PeerReviewed
    Format: text
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    ARTIKEL (OCEANREP)
  • 35
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    A solid phase extraction based non-disruptive sampling technique to investigate the surface chemistry of macroalgae (2016)
    Taylor & Francis
    In:  Biofouling, 32 (2). pp. 145-153.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: The surface chemistry of aquatic organisms determines their biotic interactions. Metabolites in the spatially limited laminar boundary layer mediate processes, such as antifouling, allelopathy and chemical defense against herbivores. However, very few methods are available for the investigation of such surface metabolites. An approach is described in which surfaces are extracted by means of C18 solid phase material. By powdering wet algal surfaces with this material, organic compounds are adsorbed and can be easily recovered for subsequent liquid chromatography/mass spectrometry (LC/MS) and gas chromatography/mass spectrometry (GC/MS) investigations. The method is robust, picks up metabolites of a broad polarity range and is easy to handle. It is more universal compared to established solvent dipping protocols and it does not cause damage to the test organisms. A protocol is introduced for the macroalgae Fucus vesiculosus, Caulerpa taxifolia and Gracilaria vermiculophylla, but it can be easily transferred to other aquatic organisms.
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  • 36
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    South-to-north pyroxenite–peridotite source variation correlated with an OIB-type to arc-type enrichment of magmas from the Payenia backarc of the Andean Southern Volcanic Zone (SVZ) (2017)
    Springer
    In:  Contributions to Mineralogy and Petrology, 172 (1). Art.No. 1.
    Details
    Publikationsdatum: 2020-02-06
    Beschreibung: New high-precision minor element analysis of the most magnesian olivine cores (Fo85–88) in fifteen high-MgO (Mg#66–74) alkali basalts or trachybasalts from the Quaternary backarc volcanic province, Payenia, of the Andean Southern Volcanic Zone in Argentina displays a clear north-to-south decrease in Mn/Feol. This is interpreted as the transition from mainly peridotite-derived melts in the north to mainly pyroxenite-derived melts in the south. The peridotite–pyroxenite source variation correlates with a transition of rock compositions from arc-type to OIB-type trace element signatures, where samples from the central part of the province are intermediate. The southernmost rocks have, e.g., relatively low La/Nb, Th/Nb and Th/La ratios as well as high Nb/U, Ce/Pb, Ba/Th and Eu/Eu* = 1.08. The northern samples are characterized by the opposite and have Eu/Eu* down to 0.86. Several incompatible trace element ratios in the rocks correlate with Mn/Feol and also reflect mixing of two geochemically distinct mantle sources. The peridotite melt end-member carries an arc signature that cannot solely be explained by fluid enrichment since these melts have relatively low Eu/Eu*, Ba/Th and high Th/La ratios, which suggest a component of upper continental crust (UCC) in the metasomatizing agent of the northern mantle. However, the addition to the mantle source of crustal materials or varying oxidation state cannot explain the variation in Mn and Mn/Fe of the melts and olivines along Payenia. Instead, the correlation between Mn/Feol and whole-rock (wr) trace element compositions is evidence of two-component mixing of melts derived from peridotite mantle source enriched by slab fluids and UCC melts and a pyroxenite mantle source with an EM1-type trace element signature. Very low Ca/Fe ratios (~1.1) in the olivines of the peridotite melt component and lower calculated partition coefficients for Ca in olivine for these samples are suggested to be caused by higher H2O contents in the magmas derived from subduction zone enriched mantle. Well-correlated Mn/Fe ratios in the wr and primitive olivines demonstrate that the Mn/Fewr of these basalts that only fractionated olivine and chromite reflects the Mn/Fe of the primitive melts and can be used as a proxy for the amount of pyroxenite melt in the magmas. Using Mn/Fewr for a large dataset of primitive Payenia rocks, we show that decreasing Mn/Fewr is correlated with decreasing Mn and increasing Zn/Mn as expected for pyroxenite melts.
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  • 37
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    Predator and prey: the role of the round goby Neogobius melanostomus in the western Baltic (2017)
    Taylor & Francis
    In:  Marine Biology Research, 13 (2). pp. 188-197.
    Details
    Publikationsdatum: 2020-01-02
    Beschreibung: Different studies on the position of the non-indigenous species Neogobius melanostomus within the coastal food web of the Pomeranian Bay (western Baltic) were performed, resulting in a quantitative and qualitative species list of prey organisms found in the stomachs of the invader and an estimation concerning the importance of round goby as prey for different resident predators. It seems that the colonization process is not fully completed yet, but the results reveal that the species is already established in the food web 16 years after the first observation within the study area. The results show that N. melanostomus feed upon a wide range of different resident organisms. While a direct predation effect on native fish species appears rather unlikely, indirect effects such as competition cannot yet be excluded. In addition, our results reveal an ontogenetic diet shift and that the round goby itself already serves as an important prey for piscivorous fish and seabirds. Finally, we formulate different hypotheses based on our results which will require further research.
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  • 38
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    Subduction initiation and ophiolite crust: new insights from IODP drilling (2017)
    Taylor & Francis
    In:  International Geology Review, 59 (11). pp. 1439-1450.
    Details
    Publikationsdatum: 2020-02-06
    Beschreibung: International Ocean Discovery Program (IODP) Expedition 352 recovered a high-fidelity record of volcanism related to subduction initiation in the Bonin fore-arc. Two sites (U1440 and U1441) located in deep water nearer to the trench recovered basalts and related rocks; two sites (U1439 and U1442) located in shallower water further from the trench recovered boninites and related rocks. Drilling in both areas ended in dolerites inferred to be sheeted intrusive rocks. The basalts apparently erupted immediately after subduction initiation and have compositions similar to those of the most depleted basalts generated by rapid sea-floor spreading at mid-ocean ridges, with little or no slab input. Subsequent melting to generate boninites involved more depleted mantle and hotter and deeper subducted components as subduction progressed and volcanism migrated away from the trench. This volcanic sequence is akin to that recorded by many ophiolites, supporting a direct link between subduction initiation, fore-arc spreading, and ophiolite genesis.
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  • 39
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    Male reproductive maturity in the octopus, Eledone cirrhosa (Cephalopoda: Octopoda) (1984)
    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 64 . pp. 573-579.
    Details
    Publikationsdatum: 2020-07-16
    Beschreibung: Males of Eledone cirrhosa grow to a size little over 600 g and normally have well-developed, and presumably active, reproductive organs from about 200 g upwards. Total weight of the genital bag is well correlated with total body weight (r= 0·906). Growth of the testis precedes that of the spermatophoric sac, and the size of neither of these reproductive components is predictable from body weight. The sizes of these organs and the estimated number and length of stored spermatophores are given for 100 g intervals of total body weight. No evidence was obtained for a seasonal trend in male maturity.
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  • 40
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    Warming has stronger direct than indirect effects on benthic microalgae in a seaweed system in spring (2017)
    Springer
    In:  Marine Biology, 164 (4). Art. No. 67.
    Details
    Publikationsdatum: 2020-02-06
    Beschreibung: Using outdoor mesocosms we investigated the relative importance of the direct and indirect (here: altered grazing) effects of seawater warming on benthic microalgae in a Baltic Sea Fucus vesiculosus (Phaeophyceae) system during the spring season. Seawater warming had a positive main effect on microalgal total biomass accrual and growth rate and on total mesograzer abundance and biomass. Moreover, under the existing resource-replete conditions in spring the direct positive effect of warming on microalgae was stronger than its indirect negative effect through enhanced grazing. The outcome of this study contrasts previous observations from the summer and winter season, where indirect effects of warming mediated by altered grazing were identified as an important driver of primary biomass in the Fucus system. In this context, the results from the spring season add mechanistic information to the overall understanding of the seasonal variability of climate change effects. They suggest that the relative importance of the underlying direct and indirect effective pathways of warming and the overall effect on the balance between production and consumption are influenced by the trophic state of the system, which in temperate regions is related to season.
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  • 41
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    Inhibitory potential of strepthonium A against Shiga toxin production in enterohemorrhagic Escherichia coli (EHEC) strain EDL933 (2017)
    Taylor & Francis
    In:  Natural Product Research, 31 (23). 2818-2823 .
    Details
    Publikationsdatum: 2020-02-06
    Beschreibung: The production of shiga toxin (Stx) is a critical step in the establishment and progress of enterohemorrhagic Escherichia coli (EHEC) infections. The possible release of Stx from dead and dying bacteria, and the risk of resistance development have restricted the usage of antibiotics against EHEC. The chlorinated quaternary ammonium compound, strepthonium A, was isolated from the culture of Streptomyces sp. SBT345 that was cultivated from the Mediterranean sponge Agelas oroides. The structure was elucidated and confirmed by spectroscopic analyses including 1D and 2D NMR, ESI-HRMS, as well as ESI-HRMS2. Strepthonium A follows Lipinski's rule of five with respect to its molecular weight, CLogP values and the number of hydrogen acceptors and donors. Verotoxin ELISA assay demonstrated that Strepthonium A reduced the Stx production in EHEC strain EDL933 at 80 μM concentration without growth inhibition. This study demonstrates the potential of strepthonium A in restraining the production of Stx in EHEC infections.
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  • 42
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    Urbanization dynamics of Tehran city (1975–2015) using artificial neural networks (2017)
    Taylor & Francis
    In:  Journal of Maps, 13 (1). pp. 24-30.
    Details
    Publikationsdatum: 2020-02-06
    Beschreibung: Land-use dynamic is a major challenge for town and country planners especially in developing countries such as Iran. Iran has been under rapid urban expansion and population growth for past three decades which led to lack of resources, environmental deterioration and haphazard landscape development. In this paper, an attempt has been made to map the urbanization dynamics of Tehran in 40 years based on remote sensing imagery and by means of artificial neural networks. The presented scheme could be taken into consideration when planning initiatives aimed at surveying, monitoring, managing and sustainable development of the territory. Moreover, it can serve the experts in the fields of geography, urban studies and planning as a background for number of geographical analyses.
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  • 43
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    Growth and Development of Spirula Spirula (1970)
    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 50 (01). pp. 53-64.
    Details
    Publikationsdatum: 2020-07-16
    Beschreibung: Spirula spirula has stimulated considerable interest since it was first discovered. It is a member of one of the two genera of sepioids to frequent oceanic water (the other being Heteroteuthis); it has a unique spiral shell which acts as a buoyancy mechanism and can withstand considerable pressure (Denton, Gilpin-Brown & Howarth, 1967); and, until the capture by the Danish Oceanographical expeditions it was considered very rare, only 12 specimens having been captured. The Dana expeditions caught 193 individuals from 1909 to 1931 and these were described by Kerr (1931) and Bruun (1943,1955). Most of these were caught in the waters around the Canary Islands of the North Atlantic. Bruun (1943) arranged the specimens according to month and size and claimed that two size groups could be distinguished. The specimens were taken over a wide geographical area, in several years and during the months of February (1 specimen), March (40), April (3), May (8), June (1), August (1) and October (23). His conclusion concerning growth depends entirely upon his decision to split the March sample into two year-groups; those above 1.9 cm in ventral mantle length he put in a separate year-class to those below 1.9 cm in ventral mantle length. This division was arbitrary and, one suspects, based on a belief that a one-year life-span was likely. Clearly the growth of Spirula requires further study based on a larger collection and the present paper is an attempt to fulfil this need.
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  • 44
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    Glacial meltwater from Greenland is not likely to be an important source of Fe to the North Atlantic (2015)
    Springer
    In:  Biogeochemistry, 124 (1-3). pp. 1-11.
    Details
    Publikationsdatum: 2018-02-05
    Beschreibung: Recent work has shown that glaciers are a globally significant source of the micronutrient Fe to the ocean. Polar regions are particularly susceptible to climate change and have been subject to pronounced warming in the past few decades. In response to this warming, the volume of glacial meltwater runoff from Greenland has increased. This meltwater has a relatively high particulate and dissolved Fe content. Seasonal Fe limitation of marine ecosystems has been found in parts of the North Atlantic, so it has been proposed that increasing fluxes of Fe rich meltwater from Greenland to the North Atlantic could alleviate this Fe limitation and thereby increase marine primary production. However, here we use a synthesis of biogeochemical and physical oceanography studies to suggest that the physical circulation around Greenland does not favour direct export of dissolved or particulate Fe from inshore to offshore waters. The Fe budget in surface waters of the North Atlantic may therefore be insensitive to increasing meltwater fluxes from Greenland.
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  • 45
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    Aerosol and Solar Irradiance Effects on Decadal Climate Variability and Predictability (2017)
    Springer
    In:  Current Climate Change Reports, 3 (2). pp. 150-162.
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    Publikationsdatum: 2020-02-06
    Beschreibung: The expanding interest in decadal climate variability, predictability, and prediction highlights the importance of understanding the sources and mechanisms of decadal and interdecadal climate fluctuations. The purpose of this paper is to provide a critical review of our current understanding of externally forced decadal climate variability. In particular, proposed mechanisms determining decadal climate responses to variations in solar activity, stratospheric volcanic aerosols, and natural as well as anthropogenic tropospheric aerosols are discussed, both separately and in a unified framework. The review suggests that the excitation of internal modes of interdecadal climate variability, particularly centered in the Pacific and North Atlantic sectors, remains a paradigm to characterize externally forced decadal climate variability and to interpret the associated dynamics. Significant recent advancements are the improved understanding of the critical dependency of volcanically forced decadal climate variability on the relative phase of ongoing internal variability and on additional external perturbations, and the recognition that associated uncertainty may represent a serious obstacle to identifying the climatic consequences even of very strong eruptions. Particularly relevant is also the recent development of hypotheses about potential mechanisms (reemergence and synchronization) underlying solar forced decadal climate variability. Finally, outstanding issues and, hence, major opportunities for progress regarding externally forced decadal climate variability are discussed. Uncertain characterization of forcing and climate histories, imperfect implementation of complex forcings in climate models, limited understanding of the internal component of interdecadal climate variability, and poor quality of its simulation are some of the enduring critical obstacles on which to progress. It is suggested that much further understanding can be gained through identification and investigation of relevant periods of forced decadal climate variability during the preindustrial past millennium. Another upcoming opportunity for progress is the analysis of focused experiments with coupled ocean–atmosphere general circulation models within the umbrella of the next phase of the coupled model intercomparison project.
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  • 46
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    Multi-angle backscatter classification and sub-bottom profiling for improved seafloor characterization (2017)
    Springer
    In:  Marine Geophysical Research, 39 (1-2). pp. 289-306.
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    Publikationsdatum: 2020-02-06
    Beschreibung: This study applies three classification methods exploiting the angular dependence of acoustic seafloor backscatter along with high resolution sub-bottom profiling for seafloor sediment characterization in the Eckernförde Bay, Baltic Sea Germany. This area is well suited for acoustic backscatter studies due to its shallowness, its smooth bathymetry and the presence of a wide range of sediment types. Backscatter data were acquired using a Seabeam1180 (180 kHz) multibeam echosounder and sub-bottom profiler data were recorded using a SES-2000 parametric sonar transmitting 6 and 12 kHz. The high density of seafloor soundings allowed extracting backscatter layers for five beam angles over a large part of the surveyed area. A Bayesian probability method was employed for sediment classification based on the backscatter variability at a single incidence angle, whereas Maximum Likelihood Classification (MLC) and Principal Components Analysis (PCA) were applied to the multi-angle layers. The Bayesian approach was used for identifying the optimum number of acoustic classes because cluster validation is carried out prior to class assignment and class outputs are ordinal categorical values. The method is based on the principle that backscatter values from a single incidence angle express a normal distribution for a particular sediment type. The resulting Bayesian classes were well correlated to median grain sizes and the percentage of coarse material. The MLC method uses angular response information from five layers of training areas extracted from the Bayesian classification map. The subsequent PCA analysis is based on the transformation of these five layers into two principal components that comprise most of the data variability. These principal components were clustered in five classes after running an external cluster validation test. In general both methods MLC and PCA, separated the various sediment types effectively, showing good agreement (kappa 〉0.7) with the Bayesian approach which also correlates well with ground truth data (r2 〉 0.7). In addition, sub-bottom data were used in conjunction with the Bayesian classification results to characterize acoustic classes with respect to their geological and stratigraphic interpretation. The joined interpretation of seafloor and sub-seafloor data sets proved to be an efficient approach for a better understanding of seafloor backscatter patchiness and to discriminate acoustically similar classes in different geological/bathymetric settings.
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  • 47
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    Biomineralization in Diatoms: The Organic Templates (2015)
    Springer
    In:  In: Evolution of Lightweight Structures. Biologically-inspired systems, 6 . Springer, Dordrecht, pp. 39-58.
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    Publikationsdatum: 2017-07-20
    Beschreibung: While the geometries of diatom frustules have been investigated in detail, the processes leading to their formation—morphogenesis and biomineralization—are not well understood. The study of organic templates, which are suspected to be important for biosilicification of diatoms, have been mainly investigated on the basis of diverse demineralization techniques. In contrast to naturally occurring dissolution of diatom cell walls in natural habitats, all experiments in vitro were based on chemical reagents including HF- or alkali-based techniques with addition of some additives as presented in this chapter. Mostly, the amino acids (serine, threonine, hydrohyproline) diverse proteinaceous materials (frustulins, pleuralins, silaffins, silacidins, circulins) as well as polyamines have been proposed to regulate biosilicification in vivo in diatoms. In this chapter, we review the biochemical pathways and potential functions of these chemical compounds and their roles in the biomineralization process. In addition, we demonstrate the presence of chitin and discuss its potential as scaffolding as well as a template material in siliceous cell walls of diatoms. The current findings show that a complex network of different organic components is responsible for the biomineralization of diatoms. Since both the organic network and the precipitated silica are integrated in the material which forms the diatom frustule, the material properties must differ from that of pure silica. As the material properties are a crucial factor for the defensive performance of the frustule and thus their survival, it is likely that organic templates for silicification play a role both for the development process and for the improvement of the material properties of the finished shells.
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  • 48
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    A new flow-through bioassay for testing low-emission antifouling coatings (2017)
    Taylor & Francis
    In:  Biofouling, 33 (8). pp. 613-623.
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    Publikationsdatum: 2020-02-06
    Beschreibung: Current antifouling (AF) technologies are based on the continuous release of biocides into the water, and consequently discharge into the environment. Major efforts to develop more environmentally friendly coatings require efficient testing in laboratory assays, followed by field studies. Barnacles are important fouling organisms worldwide, increasing hydrodynamic drag on ships and damaging coatings on underwater surfaces, and thus are extensively used as models in AF research, mostly in static, laboratory-based systems. Reliable flow-through test assays for the screening of biocide-containing AF paints, however, are rare. Herein, a flow-through bioassay was developed to screen for diverse low-release biocide paints, and to evaluate their effects on pre- and post-settlement traits in barnacles. The assay distinguishes between the effects from direct surface contact and bulk-water effects, which are crucial when developing low-emission AF coatings. This flow-through bioassay adds a new tool for rapid laboratory-based first-stage screening of candidate compounds and novel AF formulations.
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  • 49
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    Weak ENSO asymmetry due to weak nonlinear air–sea interaction in CMIP5 climate models (2016)
    Springer
    In:  Advances in Atmospheric Sciences, 33 (3). pp. 352-364.
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    Publikationsdatum: 2019-02-01
    Beschreibung: State-of-the-art climate models have long-standing intrinsic biases that limit their simulation and projection capabilities. Significantly weak ENSO asymmetry and weakly nonlinear air–sea interaction over the tropical Pacific was found in CMIP5 (Coupled Model Intercomparison Project, Phase 5) climate models compared with observation. The results suggest that a weak nonlinear air–sea interaction may play a role in the weak ENSO asymmetry. Moreover, a weak nonlinearity in air–sea interaction in the models may be associated with the biases in the mean climate—the cold biases in the equatorial central Pacific. The excessive cold tongue bias pushes the deep convection far west to the western Pacific warm pool region and suppresses its development in the central equatorial Pacific. The deep convection has difficulties in further moving to the eastern equatorial Pacific, especially during extreme El Ni˜no events, which confines the westerly wind anomaly to the western Pacific. This weakens the eastern Pacific El Ni˜no events, especially the extreme El Ni˜no events, and thus leads to the weakened ENSO asymmetry in climate models. An accurate mean state structure (especially a realistic cold tongue and deep convection) is critical to reproducing ENSO events in climate models. Our evaluation also revealed that ENSO statistics in CMIP5 climate models are slightly improved compared with those of CMIP3. The weak ENSO asymmetry in CMIP5 is closer to the observation. It is more evident in CMIP5 that strong ENSO activities are usually accompanied by strong ENSO asymmetry, and the diversity of ENSO amplitude is reduced.
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  • 50
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    Trichocitrin, a new fusicoccane diterpene from the marine brown alga-endophytic fungusTrichoderma citrinoviridecf-27 (2016)
    Taylor & Francis
    In:  Natural Product Research, 30 (14). pp. 1605-1610.
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    Publikationsdatum: 2019-02-01
    Beschreibung: One new diterpene, trichocitrin (1), and four known secondary metabolites, nafuredin (2), 5-hydroxy-2,3-dimethyl-7-methoxychromone (3), 24-methylenecycloartanol (4) and citrostadienol (5), were isolated from the culture of marine brown alga-endophytic Trichoderma citrinoviride cf-27. Trichocitrin (1) represents the first Trichoderma-derived and furan-bearing fusicoccane diterpene, and its structure and relative configuration were identified by analysis of 1D/2D NMR and mass spectroscopic data. Compounds 1 and 2 exhibited 8.0- and 9.5-mm inhibition zones, respectively, against Escherichia coli at 20 μg/disc and 54.1 and 36.7% growth inhibition, respectively, of Prorocentrum donghaiense at 80 μg/mL.
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  • 51
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    Atmospheric feedbacks in North Africa from an irrigated, afforested Sahara (2018)
    Springer
    In:  Climate Dynamics, 50 (11-12). pp. 4561-4581.
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    Publikationsdatum: 2021-02-08
    Beschreibung: Afforestation of the Sahara has been proposed as a climate engineering method to sequester a substantial amount of carbon dioxide, potentially effective to mitigate climate change. Earlier studies predicted changes in the atmospheric circulation system. These atmospheric feedbacks raise questions about the self-sustainability of such an intervention, but have not been investigated in detail. Here, we investigate changes in precipitation and circulation in response to Saharan large-scale afforestation and irrigation with NCAR’s CESM-WACCM Earth system model. Our model results show a Saharan temperature reduction by 6 K and weak precipitation enhancement by 267 mm/year over the Sahara. Only 26% of the evapotranspirated water re-precipitates over the Saharan Desert, considerably large amounts are advected southward to the Sahel zone and enhance the West African monsoon (WAM). Different processes cause circulation and precipitation changes over North Africa. The increase in atmospheric moisture leads to radiative cooling above the Sahara and increased high-level cloud coverage as well as atmospheric warming above the Sahel zone. Both lead to a circulation anomaly with descending air over the Sahara and ascending air over the Sahel zone. Together with changes in the meridional temperature gradient, this results in a southward shift of the inner-tropical front. The strengthening of the Tropical easterly jet and the northward displacement of the African easterly jet is associated with a northward displacement and strengthening of the WAM precipitation. Our results suggest complex atmospheric circulation feedbacks, which reduce the precipitation potential over an afforested Sahara and enhance WAM precipitation.
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  • 52
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    Spatial and seasonal reef calcification in corals and calcareous crusts in the central Red Sea (2016)
    Springer
    In:  Coral Reefs, 35 (2). pp. 681-693.
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    Publikationsdatum: 2019-02-01
    Beschreibung: The existence of coral reef ecosystems critically relies on the reef carbonate framework produced by scleractinian corals and calcareous crusts (i.e., crustose coralline algae). While the Red Sea harbors one of the longest connected reef systems in the world, detailed calcification data are only available from the northernmost part. To fill this knowledge gap, we measured in situ calcification rates of primary and secondary reef builders in the central Red Sea. We collected data on the major habitat-forming coral genera Porites, Acropora, and Pocillopora and also on calcareous crusts (CC) in a spatio-seasonal framework. The scope of the study comprised sheltered and exposed sites of three reefs along a cross-shelf gradient and over four seasons of the year. Calcification of all coral genera was consistent across the shelf and highest in spring. In addition, Pocillopora showed increased calcification at exposed reef sites. In contrast, CC calcification increased from nearshore, sheltered to offshore, exposed reef sites, but also varied over seasons. Comparing our data to other reef locations, calcification in the Red Sea was in the range of data collected from reefs in the Caribbean and Indo-Pacific; however, Acropora calcification estimates were at the lower end of worldwide rates. Our study shows that the increasing coral cover from nearshore to offshore environments aligned with CC calcification but not coral calcification, highlighting the potentially important role of CC in structuring reef cover and habitats. While coral calcification maxima have been typically observed during summer in many reef locations worldwide, calcification maxima during spring in the central Red Sea indicate that summer temperatures exceed the optima of reef calcifiers in this region. This study provides a foundation for comparative efforts and sets a baseline to quantify impact of future environmental change in the central Red Sea.
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  • 53
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    Chemical Flux Associated with Spatially and Temporally Variable Submarine Groundwater Discharge, and Chemical Modification in the Subterranean Estuary at Gloucester Point, VA (USA) (2016)
    Springer
    In:  Estuaries and Coasts, 39 (1). pp. 1-12.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: Submarine groundwater discharge represents a major but poorly constrained component of coastal marine chemical budgets. In the current study, the geochemical behavior of 224Ra, inorganic nitrogen species, and Fe in shallow coastal groundwater was characterized to improve estimates of chemical flux via submarine groundwater discharge (SGD) at a site in the York River estuary, VA (USA). Directly measured SGD rates varied between 3.9 ± 1.2 cm day−1 offshore, and 8.9 ± 2.6 cm day−1 close to shore. A clear inverse relationship was observed between SGD and tidal height, reflecting the hydraulic gradient between groundwater and surface water. Discharge rates varied spatially in conjunction with the subterranean estuary location, and there was a strong inverse correlation between seepage rates and seepage salinity. Dissolved 224Ra activity in the mixing zone reached levels up to 6 dpm L−1 and co-varied with salinity in the groundwater but not in the surface water or seepage water. Instead, a consistent sigmoidal trend of Ra with pH was observed, which matched previous laboratory experiment results. Dissolved NH4 + reached concentrations up to 120 μM in the groundwater and appeared to mix conservatively with respect to salinity in the subterranean estuary. In contrast, NOx (NO2 − + NO3 −) was low in both fresh groundwater and surface water and showed non-conservative enrichment (up to 23 μM) within the subterranean estuary. Dissolved Fe also showed non-conservative excess in the subterranean estuary, reaching concentrations up to 50 μM. SGD-derived chemical fluxes were estimated using several different commonly used approaches: average groundwater concentrations, pore water constituent-salinity trends coupled with directly collected seepage salinity, constituent concentrations in directly collected seepage, and concentrations in shallowest groundwater samples. Different flux estimates were compared with a “variable endmember” approach based on the observed geochemical distribution and inferred behavior.
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  • 54
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    Karl Andrée (1880–1959) sedimentologist and marine geologist (2017)
    Springer
    In:  International Journal of Earth Sciences, 106 (8). pp. 2999-3003.
    Details
    Publikationsdatum: 2020-02-06
    Beschreibung: Karl Andrée began studying questions of sedimentology and oceanography in 1908 when working as an assistant at the University of Marburg and he remained faithful to these subjects until his death in 1959. The vast majority of his scientific contributions, however, were published during his time at the University of Königsberg (1915–1945). There he published his fundamental papers on marine geology, all of which adhered strictly to the principles of uniformitarianism, and helped improve our understanding of sedimentary processes and the stratigraphic record. His scientific work has enormous breadth. In the course of 55 years, he published 124 individual papers and books, some of which became classic textbooks. His versatility is particularly evident in his book “Geology of the Seafloor”, which contains many pertinent observations and descriptions still relevant today, even if it has fallen out of fashion. This scientist and university teacher was the first to successfully present the huge field of marine geology in all its facet and to consider the deposition of marine sediments as a function of their geographical distribution.
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  • 55
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    The role and conditions of second-stage mantle melting in the generation of low-Ti tholeiites and boninites: the case of the Manihiki Plateau and the Troodos ophiolite (2017)
    Springer
    In:  Contributions to Mineralogy and Petrology, 172 (11-12, Article Nr. 104).
    Details
    Publikationsdatum: 2020-02-06
    Beschreibung: High-Mg, low-Ti volcanic rocks from the Manihiki Plateau in the Western Pacific share many geochemical characteristics with subduction-related boninites such as high-Ca boninites from the Troodos ophiolite on Cyprus, which are believed to originate by hydrous re-melting of previously depleted mantle. In this paper we compare the Manihiki rocks and Troodos boninites using a new dataset on the major and trace element composition of whole rocks and glasses from these locations, and new high-precision, electron microprobe analyses of olivine and Cr-spinel in these rocks. Our results show that both low-Ti Manihiki rocks and Troodos boninites could originate by re-melting of a previously depleted lherzolite mantle source (20–25% of total melting with 8–10% melting during the first stage), as indicated by strong depletion of magmas in more to less incompatible elements (Sm/Yb 〈 0.8, Zr/Y 〈 2, Ti/V 〈 12) and high-Cr-spinel compositions (Cr# 〉 0.5). In comparison with Troodos boninites, the low-Ti Manihiki magmas had distinctively lower H2O contents (〈 0.2 vs. 〉 2 wt% in boninites), ~ 100 °C higher liquidus temperatures at a given olivine Fo-number, lower fO2 (ΔQFM 〈 + 0.2 vs. ΔQFM 〉 + 0.2) and originated from deeper and hotter mantle (1.4–1.7 GPa, ~ 1440 °C vs. 0.8–1.0 GPa, ~ 1300 °C for Troodos boninites). The data provide new evidence that re-melting of residual upper mantle is not only restricted to subduction zones, where it occurs under hydrous conditions, but can also take place due to interaction of previously depleted upper mantle with mantle plumes from the deep and hotter Earth interior.
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  • 56
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    Implementation Strategies for Accurate and Efficient Control Volume-Based Two-Phase Hydrothermal Flow Solutions (2018)
    Springer
    In:  Transport in Porous Media, 121 (2). pp. 233-261.
    Details
    Publikationsdatum: 2021-02-08
    Beschreibung: Numerical models of magmatic hydrothermal systems have become powerful tools for linking surface and seafloor observations to chemical and fluid-dynamic processes at depth. This task requires resolving multi-phase flow over large distances of several kilometers, a wide range of pressure (p) and temperature (T) conditions, and over timescales of several thousands of years. The key numerical challenge is that realistic simulations have to consider the high nonlinearity and strong coupling of the governing conservation equations for mass and energy, while also being numerically efficient so that the required spatial and temporal scales can be resolved. Here we outline possible solutions to this problem by evaluating different implementation strategies and presenting a numerical scheme for fully coupled accurate and efficient flow solutions. The general scheme, based on the Newton–Raphson (NR) method, is presented for the simplified case of 2-D pure water convection and uses a control volume discretization on unstructured meshes. We find that the presented techniques significantly reduce the computational effort with respect to sequential/decoupled schemes. Key to this is a theta-time-differencing method for better accuracy, stability and convergence behavior of the NR-iterations, as well as improvements regarding upwinding. These features make the presented methods useful for coupled simulations of magmatic hydrothermal systems and a potential basis for future 3-D multi-phase codes.
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  • 57
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    Reflection and Refraction Seismic Methods (2017)
    Springer
    In:  In: Submarine Geomorphology. , ed. by Micallef, A. 〈https://orcid.org/0000-0002-9330-0648〉 Springer, Cham, pp. 43-62.
    Details
    Publikationsdatum: 2021-05-11
    Beschreibung: Seismic reflection and refraction methods are routinely used to illuminate sub-seafloor geological relationships, thereby providing a means to investigate a wide range of Earth processes that influence submarine geomorphology. Since the birth of seismic methods for exploration of ore bodies and petroleum in the early part of the 20th century, progressive technological advancements have ensured that the seismic method remains a fundamental geophysical tool in both the oil and gas industry and scientific research. For both marine seismic reflection and refraction methods, the primary principles are based around the notion of sending artificially-generated sound waves downward into the Earth and recording the energy that returns to recording instruments (receivers). In the case of seismic reflection, the down-going wavefield reflects off geological boundaries characterized by density and velocity contrasts before being recorded by an array of receivers. In seismic refraction experiments, the notion is to record energy that has been refracted at multiple geological boundaries before, ultimately, being refracted at a critical angle and then returning to receivers on the seafloor. Survey designs for both methods are many and varied, ranging from relatively simple two-dimensional surveys, to multi-azimuth three-dimensional surveys that illuminate the subsurface from different directions. Although the state of the art in seismic methods is continually evolving, this chapter gives some examples of modern and developing trends that are relevant to investigations into submarine geomorphology. Examples include high-resolution 3D seismic imaging, high-frequency sub-bottom profiling, waveform inversion and deep-towed seismic acquisition. The strength of the seismic reflection method lies in its ability to gain insight into structural and stratigraphic relationships beneath the seafloor, as well as in investigating fluid flow processes. The refraction method, on the other hand, is often used as the tool of choice for crustal-scale investigations into deeply-rooted geological processes that shape the seafloor, such as plate tectonics and volcanism. As with all scientific methods, seismic methods are most powerful when combined with complementary geophysical, geological or geochemical methods to address a common Earth science question.
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  • 58
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    Pteropod sedimentation patterns in different water depths observed with moored sediment traps over a 4-year period at the LTER station HAUSGARTEN in eastern Fram Strait (2015)
    Springer
    In:  Polar Biology, 38 (6). pp. 845-859.
    Details
    Publikationsdatum: 2020-11-02
    Beschreibung: Pteropods are important organisms in high-latitude ecosystems, and they are expected to severely suffer from climate change in the near future. In this study, sedimentation patterns of two pteropod species, the polar Limacina helicina and the subarctic boreal L. retroversa, are presented. Time series data received by moored sediment traps at the Long-Term Ecological Research (LTER) Observatory HAUSGARTEN in eastern Fram Strait were analyzed during the years 2008 to 2012. Results were derived from four different deployment depths (~200, 1,250, 2,400, and 2,550 m) at two different sites (79°N 04°20′E; 79°43′N 04°30′E). A species-specific sedimentation pattern was present at all depths and at both sites showing maximal flux rates during September/October for L. helicina and in November/December for L. retroversa. The polar L. helicina was outnumbered by L. retroversa (55–99 %) at both positions and at all depths supporting the recently observed trend toward the dominance of the subarctic boreal species. The largest decrease in pteropod abundance occurred within the mesopelagic zone (~200–1,250 m), indicating loss via microbial degradation and grazing. Pteropod carbonate (aragonite) amounted up to ~75 % of the total carbonate flux at 200 m and 2–13 % of the aragonite found in the shallow traps arrived at the deep sediment traps (~160 m above the seafloor), revealing the significance of pteropods in carbonate export at Fram Strait. Our results emphasize the relevance and the need for continuation of long-term studies to detect and trace changes in pteropod abundances and community composition and thus in the vertical transport of aragonite.
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  • 59
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    Subtercola vilae sp. nov., a novel actinobacterium from an extremely high-altitude cold volcano lake in Chile (2018)
    Springer
    In:  Antonie van Leeuwenhoek International Journal of General and Molecular Microbiology, 111 . pp. 955-963.
    Details
    Publikationsdatum: 2021-02-08
    Beschreibung: A novel actinobacterium, strain DB165T, was isolated from cold waters of Llullaillaco Volcano Lake (6170 m asl) in Chile. Phylogenetic analysis based on 16S rRNA gene sequences identified strain DB165T as belonging to the genus Subtercola in the family Microbacteriaceae, sharing 97.4% of sequence similarity with Subtercola frigoramans DSM 13057T, 96.7% with Subtercola lobariae DSM 103962T, and 96.1% with Subtercola boreus DSM 13056T. The cells were observed to be Gram-positive, form rods with irregular morphology, and to grow best at 10–15 °C, pH 7 and in the absence of NaCl. The cross-linkage between the amino acids in its peptidoglycan is type B2γ; 2,4-diaminobutyric acid is the diagnostic diamino acid; the major respiratory quinones are MK-9 and MK-10; and the polar lipids consist of phosphatidylglycerol, diphosphatidylglycerol, 5 glycolipids, 2 phospholipids and 5 additional polar lipids. The fatty acid profile of DB165T (5% 〉) contains iso-C14:0, iso-C16:0, anteiso-C15:0, anteiso-C17:0, and the dimethylacetal iso-C16:0 DMA. The genomic DNA G+C content of strain DB165T was determined to be 65 mol%. Based on the phylogenetic, phenotypic, and chemotaxonomic analyses presented in this study, strain DB165T (= DSM 105013T = JCM 32044T) represents a new species in the genus Subtercola, for which the name Subtercola vilae sp. nov. is proposed.
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  • 60
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    Depositional setting, provenance, and tectonic-volcanic setting of Eocene–Recent deep-sea sediments of the oceanic Izu–Bonin forearc, northwest Pacific (IODP Expedition 352) (2018)
    Taylor & Francis
    In:  International Geology Review, 60 (15). pp. 1816-1854.
    Details
    Publikationsdatum: 2021-02-08
    Beschreibung: New biostratigraphical, geochemical, and magnetic evidence is synthesized with IODP Expedition 352 shipboard results to understand the sedimentary and tectono-magmatic development of the Izu–Bonin outer forearc region. The oceanic basement of the Izu–Bonin forearc was created by supra-subduction zone seafloor spreading during early Eocene (c. 50–51 Ma). Seafloor spreading created an irregular seafloor topography on which talus locally accumulated. Oxide-rich sediments accumulated above the igneous basement by mixing of hydrothermal and pelagic sediment. Basaltic volcanism was followed by a hiatus of up to 15 million years as a result of topographic isolation or sediment bypassing. Variably tuffaceous deep-sea sediments were deposited during Oligocene to early Miocene and from mid-Miocene to Pleistocene. The sediments ponded into extensional fault-controlled basins, whereas condensed sediments accumulated on a local basement high. Oligocene nannofossil ooze accumulated together with felsic tuff that was mainly derived from the nearby Izu–Bonin arc. Accumulation of radiolarian-bearing mud, silty clay, and hydrogenous metal oxides beneath the carbonate compensation depth (CCD) characterized the early Miocene, followed by middle Miocene–Pleistocene increased carbonate preservation, deepened CCD and tephra input from both the oceanic Izu–Bonin arc and the continental margin Honshu arc. The Izu–Bonin forearc basement formed in a near-equatorial setting, with late Mesozoic arc remnants to the west. Subduction-initiation magmatism is likely to have taken place near a pre-existing continent–oceanic crust boundary. The Izu–Bonin arc migrated northward and clockwise to collide with Honshu by early Miocene, strongly influencing regional sedimentation.
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  • 61
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    The Seno Otway pockmark field and its relationship to thermogenic gas occurrence at the western margin of the Magallanes Basin (Chile) (2018)
    Springer
    In:  Geo-Marine Letters, 38 (3). pp. 227-240.
    Details
    Publikationsdatum: 2021-02-08
    Beschreibung: Pockmarks are variably sized crater-like structures that occur in young continental margin sediments. They are formed by gas eruptions and/or long-term release of fluid or gas. So far no pockmarks were known from the Pacific coast of South America between 51°S and 55°S. This article documents an extensive and previously unknown pockmark field in the Seno Otway (Otway Sound, 52°S) with multibeam bathymetry and parametric echosounding as well as sediment drill cores. Up to 31 pockmarks per square kilometer occur in water depths of 50 to 〉100 m in late glacial and Holocene sediments. They are up to 150 m wide and 10 m deep. Below and near the pockmarks, echosounder profiles image acoustic blanking as well as gas chimneys often crosscutting the 20 to 〉30 m thick glacial sediments above the acoustic basement, in particular along fault zones. Upward-migrating gas is trapped within the sediment strata, forming dome-like features. Two 5 m long piston cores from inside and outside a typical pockmark give no evidence for gas storage within the uppermost sediments. The inside core recovered poorly sorted glacial sediment, indicating reworking and re-deposition after several explosive events. The outside core documents an undisturbed stratigraphic sequence since ~15 ka. Many buried paleo-pockmarks occur directly below a prominent seismic reflector marking the mega-outflow event of the Seno Otway at 14.3 ka, lowering the proglacial lake level by about 80 m. This decompression would have led to frequent eruptions of gas trapped in reservoirs below the glacial sediments. However, the sediment fill of pockmarks formed after this event suggests recurrent events throughout the Holocene until today. Most pockmarks occur above folded hydrocarbon-bearing Upper Cretaceous and Paleogene rocks near the western margin of the Magallanes Basin, constraining them as likely source rocks for thermogenic gas.
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  • 62
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    Sediment–well interaction during depressurization (2017)
    Springer
    In:  Acta Geotechnica, 12 (4). pp. 883-895.
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    Publikationsdatum: 2020-04-23
    Beschreibung: Depressurization gives rise to complex sediment– well interactions that may cause the failure of wells. The situation is aggravated when high depressurization is imposed on sediments subjected to an initially low effective stress, such as in gas production from hydrate accumulations in marine sediments. Sediment–well interaction is examined using a nonlinear finite element simulator. The hydro-mechanically coupled model represents the sediment as a Cam-Clay material, uses a continuous function to capture compressibility from low to high effective stress, and recognizes the dependency of hydraulic conductivity on void ratio. Results highlight the critical effect of hydromechanical coupling as compared to constant permeability models: A compact sediment shell develops against the screen, the depressurization zone is significantly smaller than the volume anticipated assuming constant permeability, settlement decreases, and the axial load on the well decreases; in the case of hydrates, gas production will be a small fraction of the mass estimated using a constant permeability model. High compressive axial forces develop in the casing within the production horizon, and the peak force can exceed the yield capacity of the casing and cause its collapse. Also tensile axial forces may develop in the casing above the production horizon as the sediment compacts in the depressurized zone and pulls down from the well. Well engineering should consider: slip joints to accommodate extensional displacement above the production zone, soft telescopic/sliding screen design to minimize the buildup of compressive axial force within the production horizon, and enlarged gravel pack to extend the size of the depressurized zone.
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  • 63
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    Impact of Spawning Substrate Complexity on Egg Survival of Atlantic Herring (Clupea harengus, L.) in the Baltic Sea (2018)
    Springer
    In:  Estuaries and Coasts, 41 (2). pp. 549-559.
    Details
    Publikationsdatum: 2021-02-08
    Beschreibung: Shallow shore zones are generally considered to provide juvenile habitats for many invertebrate and fish species and additionally serve as spawning grounds for important components of oceanic food webs and fishery resources such as herring (Clupea spp.). Herring attach their demersal eggs to benthic substrates, rendering reproduction success vulnerable to environmental changes and local habitat alterations. However, little information is available on the effects of different substrates on the survival of demersal eggs. Hypothesizing that the structural complexity of spawning substrates generally affects herring egg survival and that the effect magnitude depends on the suitability of ambient environment, field experiments were conducted on a major spawning ground of C. harengus in the Southwestern Baltic Sea. Herring eggs were artificially spawned on substrates of different structural complexities and incubated in situ under differing temperature regimes, at the beginning and the end of the natural herring spawning season, to include the full suite of stressors occurring on littoral spawning beds. Results of this study indicate a positive relation between high structural complexity of spawning substrates and herring egg survival. Mean egg mortality was three times higher on substrates of lowest complexity than on highly complex substrates. These differences became even more prominent under unfavorable conditions that appeared with rising water temperatures later in the spawning season. Although the mechanisms are still unclear, we conclude that structural complexity, particularly formed by submerged aquatic vegetation, provides a crucial prerequisite for the successful reproduction of substrate spawning marine fishes such as herring in the Baltic Sea.
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  • 64
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    Genetic diversity of a hitchhiker and prized food source in the Anthropocene: the Asian green mussel Perna viridis (Mollusca, Mytilidae) (2018)
    Springer
    In:  Biological Invasions, 20 (7). pp. 1749-1770.
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    Publikationsdatum: 2021-02-08
    Beschreibung: Insight into a species’ native and introduced range is essential in understanding the invasion process. Genetic diversity, propagule pressure and environmental conditions all have been recognised as playing a determinant role in invasion success. Here, we aimed to investigate the genetic diversity and population genetic structure (using the COI mtDNA gene region and 22 nDNA microsatellite markers) of the Asian green mussel Perna viridis within its potential native range in Asia and at introduced locations in the USA and the Caribbean. We also analyse genetic data from vessel intercepts and an incursion. By doing so, we aimed to identify genetic signatures that could allow to track vessel samples to their source and provide further insight into potential high-risk invasive populations or areas. Three top hierarchical clusters were identified using the individual-based Bayesian clustering method in STRUCTURE, corresponding to populations in three world regions: (1) USA and Caribbean, (2) India and (3) Southeast Asia. Within Southeast Asia, additional analysis indicate a shallow genetic differentiation of three subgroups consisting of (3a) Thailand, (3b) Taiwan and Hong-Kong, and (3c) a cluster of Singapore–Indonesia samples. Overall, the population structure found in this study suggests that the markers used could be useful in identifying source populations, particularly between the three mains world regions. Most surprisingly however, this study shows that the genetic diversity of samples collected from vessel intercepts and incursions did not differ significantly from established populations in Southeast Asia. In this region, in addition to the high vessel connectivity and number of P. viridis transported, all sampled populations are likely to pose a comparable risk in terms of genetic diversity. The present work represents the most comprehensive population genetic study of P. viridis, and the first to address the potential genetic introduction risk posed by populations of this species. The information and genetic markers in this study constitute a valuable addition to the tools already used to infer on potential high-risk source populations of P. viridis. They should therefore prove useful for biosecurity surveillance and management actions directed at this species.
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  • 65
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    Melting and Mantle Sources in the Azores (2018)
    Springer
    In:  In: Volcanoes of the Azores. , ed. by Kueppers, U. and Beier, C. Volcanoes of the World . Springer, Berlin, pp. 251-280.
    Details
    Publikationsdatum: 2018-02-26
    Beschreibung: The Azores archipelago is geochemically distinct amongst the oceanic intraplate volcanoes in that it has trace element and radiogenic Sr–Nd–Pb–Hf isotope signatures that cover much of the global variation observed in Ocean Island Basalts. Thus, it is the prime example of an intraplate melting anomaly preserving the compositional heterogeneity of the Earth’s mantle. Here, we review the trace element and radiogenic isotope geochemistry of the Azores islands and few submarine samples analysed and published over the past decades and summarise these findings and conclusions. The volcanoes of all islands erupted lavas of the alkaline series and their compositions broadly range from basalts to trachytes (see also Chapter “ Petrology of the Azores Islands” by Larrea et al.). Temperatures and pressures of melting imply that melting in the Azores occurs as a result of both slightly increased temperatures in the mantle (~35 °C) and addition of volatile elements into the mantle source. Basalts from the island of São Miguel show a stronger enrichment in highly incompatible elements like K and the Light Rare Earth Elements than the other islands further to the west. The older and easternmost island Santa Maria has lavas that are more silica-undersaturated than the rocks occurring on the younger islands. Each of the eastern islands shows a different and distinct radiogenic isotope composition and much of this variability can be explained by variably enriched recycled components of different age in their source regions. Amongst the global array, the lavas from eastern São Miguel are uniquely enriched in that they display radiogenic 206Pb/204Pb, 208Pb/204Pb and 87Sr/86Sr isotope ratios best explained by a distinct source in the mantle. The implication of the preservation of such unique, enriched sources in the mantle may indicate that stirring processes in the Azores mantle are not efficiently homogenising heterogeneities over the timescales of recycling of 0.1–1 Ga and possibly even up to 2.5 Ga. One possible explanation is the low buoyancy flux of the Azores mantle when compared to other intraplate settings. The preservation of these source signatures in the lavas on the easternmost Azores islands are the result of smaller degrees of partial melting due to a thicker lithosphere. This likely prevents a homogenisation during magma ascent compared to the western islands, preferentially sampling deep, low degree partial melts from the more fertile mantle sources. The geochemical signatures of the two islands west of the Mid-Atlantic Ridge (Corvo and Flores) imply a source enrichment and degrees of partial melting similar to those east of the ridge. Melting underneath the western islands is the result of a source that must be related to the Azores melting anomaly but has been modified by shallow level processes such as assimilation of oceanic crustal material.
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  • 66
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    The influence of temperature, sex and chela size in the foraging strategy of the shore crab,Carcinus maenas(L.) (1980)
    Taylor & Francis
    In:  Marine Behaviour and Physiology, 7 (1). pp. 15-24.
    Details
    Publikationsdatum: 2018-04-18
    Beschreibung: Foraging rate was highly variable among shore crabs of the same size category and for individual crabs from day to day. Possible physiological reasons for this variability are discussed. Shore crab foraging rate, both in terms of mussels eaten per day and energy intake per day, was estimated to be higher at 17°C than at 10°C. The shape of diet curves and their mode for male shore crabs at 17°C closely resembled those for 10°C, indicating that the temperature increase had no effect on their previously demonstrated optimal foraging strategy. Female and certain male shore crabs showed a preference for prey smaller than for other equivalent sized males. These suboptimally feeding male and female crabs attained a relatively higher prédation rate (mussels day‐1), although their energy intake (KJ day‐1) remained lower than that of optimally feeding males. Preferred mussel size, number of mussels eaten per day and energy intake were strongly related to master chela height. The diet curves for female and suboptimally feeding male shore crabs could be explained by these crabs’ proportionately smaller master chelae.
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  • 67
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    The colonial ascidian Diplosoma listerianum enhances the occurrence of the hydrozoan Obelia sp. during early phases of succession (2018)
    Springer
    In:  Helgoland Marine Research, 72 (1). Art.Nr. 4.
    Details
    Publikationsdatum: 2021-03-19
    Beschreibung: Recruitment patterns of sessile species often do not reflect the composition of the local propagule pool. This is, among other processes, attributed to the stimulation or inhibition of settlement by resident species. In an experimental study, we evaluated the effects of different densities of the ascidian Diplosoma listerianum on the settlement of the hydrozoan Obelia sp. For this, we monitored the cover of the dominant fouler Obelia sp. on vertically orientated PVC tiles, which were either bare or pre-seeded with two different densities (sparse or dense) of Diplosoma colonies, over the course of 8 weeks. The settlement tiles were deployed at two study sites in La Herradura Bay, Chile. The presence of D. listerianum enhanced the settlement or the growth or both of the colonial hydrozoan, but this effect disappeared within 4–8 weeks. Furthermore, we tested whether the initial enhancement of Obelia sp. by Diplosoma colonies goes back to the fact that larvae, which reject the ascidian tunic as a settlement substratum after a first contact, colonize nearby surfaces because of their limited mobility. However, we found no support for this assumption. We rather suggest that D. listerianum facilitated colonization indirectly by the accumulation of organic material in its vicinity and/or by its pumping activity. Initial resident-mediated enhancement of the hydrozoan was overridden by processes such as competition between later colonizers within the course of weeks and we could not detect any lasting effects of D. listerianum on the structure of the developing communities.
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  • 68
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    Integral models for bubble, droplet, and multiphase plume dynamics in stratification and crossflow (2018)
    Springer
    In:  Environmental Fluid Mechanics, 18 (5). pp. 1167-1202.
    Details
    Publikationsdatum: 2021-02-08
    Beschreibung: We present the development and validation of a numerical modeling suite for bubble and droplet dynamics of multiphase plumes in the environment. This modeling suite includes real-fluid equations of state, Lagrangian particle tracking, and two different integral plume models: an Eulerian model for a double-plume integral model in quiescent stratification and a Lagrangian integral model for multiphase plumes in stratified crossflows. Here, we report a particle tracking algorithm for dispersed-phase particles within the Lagrangian integral plume model and a comprehensive validation of the Lagrangian plume model for single- and multiphase buoyant jets. The model utilizes literature values for all entrainment and spreading coefficients and has one remaining calibration parameter (Formula presented.), which reduces the buoyant force of dispersed phase particles as they approach the edge of a Lagrangian plume element, eventually separating from the plume as it bends over in a crossflow. We report the calibrated form (Formula presented.), where b is the plume half-width, and r is the distance of a particle from the plume centerline. We apply the validated modeling suite to simulate two test cases of a subsea oil well blowout in a stratification-dominated crossflow. These tests confirm that errors from overlapping plume elements in the Lagrangian integral model during intrusion formation for a weak crossflow are negligible for predicting intrusion depth and the fate of oil droplets in the plume. The Lagrangian integral model has the added advantages of being able to account for entrainment from an arbitrary crossflow, predict the intrusion of small gas bubbles and oil droplets when appropriate, and track the pathways of individual bubbles and droplets after they separate from the main plume or intrusion layer.
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  • 69
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    Late glacial to Holocene water level and climate changes in the Gulf of Gemlik, Sea of Marmara: evidence from multi-proxy data (2017)
    Springer
    In:  Geo-Marine Letters, 37 (5). pp. 501-513.
    Details
    Publikationsdatum: 2020-02-06
    Beschreibung: Multi-proxy analyses of new piston core M13-08 together with seismic data from the Gulf of Gemlik provide a detailed record of paleoceanographic and paleoclimatic changes with special emphasis on the timing of the connections between the Sea of Marmara (SoM) and the Gulf of Gemlik during the late Pleistocene to Holocene. The deposition of a subaqueous delta sourced from the Armutlu River to the north is attributed to the lowstand lake level at −60 m in the gulf prior to 13.5 cal ka BP. On the basis of the seismic data, it is argued that the higher lake level (−60 m) in the gulf compared to the SoM level (−85 m) attests to its disconnection from the SoM during the late glacial period. Ponto-Caspian assemblages in the lacustrine sedimentary unit covering the time period between 13.5 and 12 cal ka BP represent a relict that was introduced into the gulf by a Black Sea outflow during the marine isotope stage 3 interstadial. Contrary to the findings of previous studies, the data suggest that such an outflow into the Gulf of Gemlik during the late glacial period could have occurred only if the SoM lake level (−85 m) was shallower than the sill depth (−55 m) of the gulf in the west. A robust age model of the core indicates the connection of the gulf with the marine SoM at 12 cal ka BP, consistent with the sill depth (−55 m) of the gulf on the global sea level curve. Strong evidence of a marine incursion into the gulf is well documented by the μ-XRF Sr/Ca data. The available profiles of elemental ratios in core M13-08, together with the age-depth model, imply that a warm and wet climate prevailed in the gulf during the early Holocene (12–10.1 cal ka BP), whereas the longest drought occurred during the middle Holocene (8.2–5.4 cal ka BP). The base of the main Holocene sapropel in the gulf is dated at 10.1 cal ka BP, i.e., 500 years younger than its equivalent in the SoM. The late Holocene is earmarked by warm and wet climate periods (5.0–4.2 and 4.2–2.7 cal ka BP) with some brief cold/dry periods (4.2 and 2.7–0.9 cal ka BP).
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  • 70
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    Inter-laboratory study for the certification of trace elements in seawater certified reference materials NASS-7 and CASS-6 (2018)
    Springer
    In:  Analytical and Bioanalytical Chemistry, 410 (18). pp. 4469-4479.
    Details
    Publikationsdatum: 2021-04-23
    Beschreibung: Certification of trace metals in seawater certified reference materials (CRMs) NASS-7 and CASS-6 is described. At the National Research Council Canada (NRC), column separation was performed to remove the seawater matrix prior to the determination of Cd, Cr, Cu, Fe, Pb, Mn, Mo, Ni, U, V, and Zn, whereas As was directly measured in 10-fold diluted seawater samples, and B was directly measured in 200-fold diluted seawater samples. High-resolution inductively coupled plasma mass spectrometry (HR-ICPMS) was used for elemental analyses, with double isotope dilution for the accurate determination of B, Cd, Cr, Cu, Fe, Pb, Mo, Ni, U, and Zn in seawater NASS-7 and CASS-6, and standard addition calibration for As, Co, Mn, and V. In addition, all analytes were measured using standard addition calibration with triple quadrupole (QQQ)-ICPMS to provide a second set of data at NRC. Expert laboratories worldwide were invited to contribute data to the certification of trace metals in NASS-7 and CASS-6. Various analytical methods were employed by participants including column separation, co-precipitation, and simple dilution coupled to ICPMS detection or flow injection analysis coupled to chemiluminescence detection, with use of double isotope dilution calibration, matrix matching external calibration, and standard addition calibration. Results presented in this study show that majority of laboratories have demonstrated their measurement capabilities for the accurate determination of trace metals in seawater. As a result of this comparison, certified/reference values and associated uncertainties were assigned for 14 elements in seawater CRMs NASS-7 and CASS-6, suitable for the validation of methods used for seawater analysis.
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  • 71
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    Fluctuations in the strength of chemical antifouling defenses in a red macroalga in response to variations in epibiont colonization pressure (2018)
    Springer
    In:  Marine Biology, 165 (6). p. 107.
    Details
    Publikationsdatum: 2021-02-08
    Beschreibung: Marine macroalgae in temperate regions are constantly exposed to colonization by fouling organisms, but the intensity of fouling fluctuates in time. We, therefore, hypothesized that a macroalgal species from these latitudes should be able to adjust its antifouling defense to the prevailing colonization pressure. To test this assumption, fouling pressure in the Western Baltic Sea as well as the activity of surface extracts gained from the non-native Gracilaria vermiculophylla against the diatom Stauroneis constricta and the filamentous alga Ceramium tenuicorne were assessed over one vegetation period on a monthly basis. We used two solvents with different polarities to extract chemical compounds from the alga. Both, hexane and dichloromethane (DCM) surface extracts, inhibited settlement of C. tenuicorne, while only hexane surface extracts deterred S. constricta. Furthermore, the activities of both extracts fluctuated on the scale of months and the fluctuations in the activity against C. tenuicorne, which were observed in DCM extracts, correlated with the intensity of fouling pressure that C. tenuicorne inflicted on G. vermiculophylla in the field. Thus, G. vermiculophylla appears to be able to adjust its antifouling defenses—at least partly—to fouling pressure.
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  • 72
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    Dynamics of exrtrusive dome growth and variations in chemical and mineralogical composition of Young Shiveluch andesites in 2001–2013 (2016)
    Springer
    In:  Journal of Volcanology and Seismology, 10 (6). pp. 360-381.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: This paper discribes characteristic features of the extrusive dome growth of the Young Shiveluch Volcano in 2001–2013 and analyzes variations in the chemical and mineralogic composition of magmas erupted during this period. It is shown that, compared with the earlier phases in the dome growth during 1980–1981 and 1993–1995, the andesites that were erupted in the 2000s are less homogeneous in bulk composition, crystal contents and contain phenocrysts, which differ in composition and the conditions of crystallization. These compositional feature of rocks are interpreted as resulting from convection in a shallow magma chamber, with the convection being caused by the arrival of a fresh portion of deep magma.
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  • 73
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    Radiolarians from the surface sediment in Lindåspollene, Western Norway (1973)
    Taylor & Francis
    In:  Sarsia, 53 (1). pp. 71-75.
    Details
    Publikationsdatum: 2020-05-28
    Beschreibung: Sixtytwo species of radiolarians have been found in surface sediment in Lindåspollene. Some of these are common in deep-sea sediments from tropical and subtropical latitudes. These warm-water radiolarians are believed to have been introduced during a warm, postglacial period.
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  • 74
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    Zoning in highly alkaline magma bodies (1984)
    Cambridge University Press
    In:  Geological Magazine, 121 (6). pp. 563-575.
    Details
    Publikationsdatum: 2020-07-31
    Beschreibung: We present chemical data on magmatically heterogeneous pyroclastic deposits of late Quaternary age erupted from zoned magma systems underlying Tenerife (Canary Islands), Sao Miguel and Faial (Azores), and Vesuvius. The most fractionated magmas present at each centre are respectively Na-rich phonolite, trachyte, and K-rich phonolite. Within any one deposit, chemical variation is either accompanied by changes in the phenocryst assemblage (petrographic zonation) or is largely manifested in trace element abundances, unaccompanied by any petrographic change (occult zonation). Zoning is analogous to that in calc-alkaline systems where the most fractionated products are high-silica rhyolites. When a range of magma types are considered, a correlation emerges between roofward depletion of trace elements (especially REE) in the zoned system and compatability of those same trace elements in the accessory phenocryst phases present. Thus, allanite- or chevkinite-bearing rhyolitic systems are light-REE depleted roofwards, the sphene-bearing Tenerife system is middle-REE depleted roofwards, the melanite-bearing Vesuvius system is heavy-REE depleted roofwards, while the Azores systems, which lack these phases, display roofward REE enrichment. Therefore, the behaviour of trace elements may in each case be explained by fractionation of observed phenocryst assemblages. The resemblance between features of zoned magma systems and published work on the dynamic consequences of cooling saturated aqueous solutions prompts us to suggest that sidewall crystallization and consequent boundary-layer uprise to form a capping layer at top of the system may be a plausible mechanism for the generation of both petrographic and occult zonation. Reverse zoning occurs among the first-erupted tephra of some deposits, demonstrating that the most highly differentiated magma available is not always the first to be tapped during an eruption from a zoned system.
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  • 75
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    Impact of ENSO on East Asian winter monsoon during interglacial periods: effect of orbital forcing (2017)
    Springer
    In:  Climate Dynamics, 49 (9-10). pp. 3209-3219.
    Details
    Publikationsdatum: 2020-02-06
    Beschreibung: Orbital forcing influences climate phenomena by changing incoming solar radiation in season and latitude. Here, changes in the El Niño-Southern Oscillation (ENSO)’s impact on the East Asian winter monsoon (EAWM) due to orbital forcing, especially for three selected time periods in each of two interglacial periods, the Eemian (126, 122, 115 ka) and Holocene (9, 6, 0 ka), are investigated. There was a high negative correlation between ENSO and EAWM when the obliquity was low, the processional angle was large, and especially when accompanied by large eccentricity, which corresponds to a weaker monsoon period. The correlation was also high when ENSO variability was high, which interestingly corresponded to lower obliquity and higher-degree precession periods. Therefore, as both lower obliquity and higher-degree precession, such as during 115 ka and 0 ka, cause the EAWM to be weakened through higher winter insolation over Northern hemisphere, and the ENSO to be enhanced through an intensified zonal contrast of the equatorial sea surface temperature, the relationship between the ENSO and EAWM becomes tighter. The opposite case (i.e., during 126 and 9 ka) is also true dynamically. Furthermore, the sensitivity of boreal winter precipitation against sea surface temperature (SST) anomaly over the tropical Pacific, which depends on mean SST, was positively correlated to the strength of the ENSO-EAWM correlation, implying that the warmer mean ocean surface causes the strong response of atmosphere to change in the SST anomaly, thereby enhancing the impact of ENSO on EAWM. Warmer wintertime tropical SST is attributed to higher insolation over the tropics, especially during 115 and 0 ka, while cooler SSTs occurred during 126 and 9 ka.
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  • 76
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    The female reproductive cycle of the octopus, Eledone cirrhosa (1983)
    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 63 . pp. 71-83.
    Details
    Publikationsdatum: 2020-07-16
    Beschreibung: Changes in the relative size of the ovary, oviducal glands and eggs are described for Eledone cirrhosa captured from the North Sea off Aberdeen over a 3 year period (N = 488). The analysis is based only on freshly caught animals, excluding those held in aquarium conditions (〉 5 days). Ovary enlargement and egg size estimates are used as indices of sexual maturity. Between 0–15% and 18–95% of total body weight is contributed by the ovary. Maximum egg length in the ovary ranges up to 7 mm. On these criteria, sexual maturation typically occurs at body sizes between 400–1000 g although some animals of 1000–1200 g are found showing no evidence of ovary enlargement. The majority of the monthly sample is always immature but maturation can apparently occur at almost any time of the year. Increase in mean ovary index and mean values for egg size are strongly seasonal and indicate a peak incidence of sexual maturity over 2–3 months in the July-September period. Spawning is presumed to follow within 1 month. Estimates of the fecundity of the females, based on the egg sample from the ovary, range from 2·2 × 103 to 55 × 10 3 eggs with a mean of 11 × 10 3 and a mode of 7·5 × 10 3 eggs.
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  • 77
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    Reproductive maturity in fresh and aquarium-held Eledone cirrhosa (Cephalopoda: Octopoda) (1984)
    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 64 . pp. 581-585.
    Details
    Publikationsdatum: 2020-07-16
    Beschreibung: Female Eledone cirrhosa held in aquarium conditions for periods of time of five daysand over show relatively enlarged ovary sizes. Values for ovary index considerably exceed thoseof freshly caught animals and the incidence of the final stage of maturity, in which eggs pack the oviducts, is greater. A comparison of maturity indices for fresh and aquarium males was inconclusive. The range of factors associated with aquarium conditions is briefly reviewed and it is concluded that studies of cephalopod reproductive maturation must distinguish fresh and aquarium animals. Introduction External factors effective in inducing sexual maturation in cephalopods have been suggested several times. The influence of the absence of light has been implicated since the experiments of Wells & Wells (1959) showed that blinded Octopus vulgar is matured precociously. An effect of short day length in stimulating the optic glands of Sepia has been found by Defretin & Richard (1967) and Richard (1967) but this is not clearly the case for Octopus (Buckley, 1977). Octopuses kept in aquarium conditions for lengthy periods are said to have larger relative gonad sizes than those fresh from the sea (Wells & Wells, 1975). One of the factors associated with aquarium conditions is often a degree of starvation, and this circumstance alone is held to be a factor in inducing precocious sexual maturation in Eledone (Mangold & Boucher-Rodoni, 1973). In the course of recent studies on the growth and reproduction of Eledone cirrhosa from the North Sea (Boyle & Knobloch, 1982,1983,1984) animals which had remained in aquarium conditions for 5 days or over were separated from the analysis.
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  • 78
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    Development of Mining Technology and Equipment for Seafloor Massive Sulfide Deposits (2016)
    Chinese Mechanical Engineering Society | Springer
    In:  Chinese Journal of Mechanical Engineering, 29 (5). pp. 863-870.
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    Publikationsdatum: 2020-07-27
    Beschreibung: Seafloor massive sulfide(SMS) deposits which consist of Au, Ag, Cu, and other metal elements, have been a target of commercial mining in recent decades. The demand for established and reliable commercial mining system for SMS deposits is increasing within the marine mining industry. The current status and progress of mining technology and equipment for SMS deposits are introduced. First, the mining technology and other recent developments of SMS deposits are comprehensively explained and analyzed. The seafloor production tools manufactured by Nautilus Minerals and similar mining tools from Japan for SMS deposits are compared and discussed in turn. Second, SMS deposit mining technology research being conducted in China is described, and a new SMS deposits mining tool is designed according to the environmental requirement. Finally, some new trends of mining technology of SMS deposits are summarized and analyzed. All of these conclusions and results have reference value and guiding significance for the research of SMS deposit mining in China.
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  • 79
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    Cephalopods of the Sargasso Sea: distribution patterns in relation to oceanography (2017)
    Springer
    In:  Marine Biodiversity, 47 (3). pp. 685-697.
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    Publikationsdatum: 2020-02-06
    Beschreibung: Here, we report on a comprehensive collection of mainly early life cephalopods that were sampled during a research cruise to the Sargasso Sea with the RV Maria S. Merian in April 2015. A total of 2466 cephalopods were caught which belonged to at least 27 species (17 families). The most abundant family was represented by the hooked squids (Onychoteuthidae) with a share of 19.18% of the total cephalopod catch. The subtropical convergence zone (STCZ) was found approximately around 27 °N. The STCZ was characterised by a sharp near-surface temperature gradient and divided the Sargasso Sea into a northern and a southern area. This division was also reflected in the cephalopod community composition. For example, the cranchiid Leachia lemur prevailed in the northern part, and the incirrate octopod, Japetella diaphana, was mainly distributed in the southern part of the study area. Principal component analysis (PCA) and redundancy analysis (RDA) analyses detected a significant correlation between species occurrence and sea surface temperature (SST) as well as a longitudinal gradient with distinct clusters along the five transects from west to east. Ordination analysis (MDS) showed significant differences in the cephalopod assemblages between day and night with midwater forms (Enoploteuthidae, Pyroteuthidae) dominating the night catches, probably due to their upward migration into the top 200 m during the night.
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  • 80
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    Simulation by CMIP5 models of the atlantic multidecadal oscillation and its climate impacts (2016)
    Springer
    In:  Advances in Atmospheric Sciences, 33 (12). pp. 1329-1342.
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    Publikationsdatum: 2020-04-23
    Beschreibung: This study focuses on the climatic impacts of the Atlantic Multidecadal Oscillation (AMO) as a mode of internal variability. Given the difficulties involved in excluding the effects of external forcing from internal variation, i.e., owing to the short record length of instrumental observations and historical simulations, we assess and compare the AMO and its related climatic impacts both in observations and in the “Pre-industrial” experiments of models participating in CMIP5. First, we evaluate the skill of the 25 CMIP5 models’ “Historical” simulations in simulating the observational AMO, and find there is generally a considerable range of skill among them in this regard. Six of the models with higher skill relative to the other models are selected to investigate the AMO-related climate impacts, and it is found that their “Pre-industrial” simulations capture the essential features of the AMO. A positive AMO favors warmer surface temperature around the North Atlantic, and the Atlantic ITCZ shifts northward leading to more rainfall in the Sahel and less rainfall in Brazil. Furthermore, the results confirm the existence of a teleconnection between the AMO and East Asian surface temperature, as well as the late withdrawal of the Indian summer monsoon, during positive AMO phases. These connections could be mainly caused by internal climate variability. Opposite patterns are true for the negative phase of the AMO.
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  • 81
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    Biological and chemical diversity in Antarctica: from new species to new natural products (2016)
    Taylor & Francis
    In:  Biodiversity, 17 (1-2). pp. 5-11.
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    Publikationsdatum: 2017-03-31
    Beschreibung: Antarctica is a still unexplored area in many respects, among which biological diversity and, even more so, chemical diversity are important challenges. Over recent years, our research group has been studying marine benthic ecosystems in different Antarctic areas. These studies yielded several interesting discoveries, including species new to science, as well as new natural products never seen before. Overall, we have been trying to unravel the complex network of interactions that exist between marine benthic organisms in these cold and hardly accessible ecosystems. We present here an overview of our recent results regarding the biological and the chemical diversity of these organisms. In fact, these ecosystems are as complex as many other marine environments on the planet, and indeed, many questions remain yet to be answered.
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  • 82
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    The missing half of the subduction factory: shipboard results from the Izu rear arc, IODP Expedition 350 (2017)
    Taylor & Francis
    In:  International Geology Review, 59 (13). pp. 1677-1708.
    Details
    Publikationsdatum: 2020-02-06
    Beschreibung: IODP Expedition 350 was the first to be drilled in the rear part of the Izu-Bonin, although several sites had been drilled in the arc axis to fore-arc region; the scientific objective was to understand the evolution of the Izu rear arc, by drilling a deep-water volcaniclastic section with a long temporal record (Site U1437). The Izu rear arc is dominated by a series of basaltic to dacitic seamount chains up to ~100-km long roughly perpendicular to the arc front. Dredge samples from these are geochemically distinct from arc front rocks, and drilling was undertaken to understand this arc asymmetry. Site U1437 lies in an ~20-km-wide basin between two rear arc seamount chains, ~90-km west of the arc front, and was drilled to 1804 m below the sea floor (mbsf) with excellent recovery. We expected to drill a volcaniclastic apron, but the section is much more mud-rich than expected (~60%), and the remaining fraction of the section is much finer-grained than predicted from its position within the Izu arc, composed half of ashes/tuffs, and half of lapilli tuffs of fine grain size (clasts 〈3 cm). Volcanic blocks (〉6.4 cm) are only sparsely scattered through the lowermost 25% of the section, and only one igneous unit was encountered, a rhyolite peperite intrusion at ~1390 mbsf. The lowest biostratigaphic datum is at 867 mbsf (~6.5 Ma), the lowest palaeomagnetic datum is at ~1300 mbsf (~9 Ma), and the rhyolite peperite at ~1390 mbsf has yielded a U–Pb zircon concordia intercept age of (13.6 + 1.6/−1.7) Ma. Both arc front and rear arc sources contributed to the fine-grained (distal) tephras of the upper 1320 m, but the coarse-grained (proximal) volcaniclastics in the lowest 25% of the section are geochemically similar to the arc front, suggesting arc asymmetry is not recorded in rocks older than ~13 Ma.
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  • 83
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    Is the chemical composition of biomass the agent by which ocean acidification impacts on zooplankton ecology? (2017)
    Springer
    In:  Aquatic Sciences, 79 (3). pp. 733-748.
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    Publikationsdatum: 2020-02-06
    Beschreibung: Climate change impacts prevail on marine pelagic systems and food webs, including zooplankton, the key link between primary producers and fish. Several metabolic, physiological, and ecological responses of zooplankton species and communities to global stressors have recently been tested, with an emerging field in assessing effects of combined climate-related factors. Yet, integrative studies are needed to understand how ocean acidification interacts with global warming, mediating zooplankton body chemistry and ecology. Here, we tested the combined effects of global warming and ocean acidification, predicted for the year 2100, on a community of calanoid copepods, a ubiquitously important mesozooplankton compartment. Warming combined with tested pCO2 increase affected metabolism, altered stable isotope composition and fatty acid contents, and reduced zooplankton fitness, leading to lower copepodite abundances and decreased body sizes, and ultimately reduced survival. These interactive effects of temperature and acidification indicate that metabolism-driven chemical responses may be the underlying correlates of ecological effects observed in zooplankton communities, and highlight the importance of testing combined stressors with a regression approach when identifying possible effects on higher trophic levels.
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  • 84
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    Evidence for Changes in Estuarine Zooplankton Fostered by Increased Climate Variance (2018)
    Springer
    In:  Ecosystems, 21 (1). pp. 56-67.
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    Publikationsdatum: 2021-02-08
    Beschreibung: Estuaries are among the most valuable aquatic systems in terms of their services to human welfare. They offer an ideal framework to assess multiscale processes linking climate and food web dynamics through the hydrological cycle. Resolving food web responses to climate change is fundamental to resilience management of these threatened ecosystems under global change scenarios. Here, we examined the temporal variability of the plankton food web in the Mondego Estuary, central Iberian Peninsula, over the period 2003 to 2012. The results pointed out a cascading effect from climate to plankton communities that follow a non-stationary behavior shaped by the climate variance envelope. Concurrent changes in hydrographic processes at the regional, that is, upwelling intensity, and local, that is, estuarine hydrology, scales were driven by climatic forcing promoted by the North Atlantic Oscillation; the influence of which permeated the physical environment in the estuary affecting both autotrophic and heterotrophic communities. The most conspicuous change arose around 2008 and consisted of an obvious decrease in freshwater taxa along with a noticeable increase in marine organisms, mainly driven by gelatinous zooplankton. The observed increase in small-sized cosmopolitan copepods, that is, Clausocalanus arcuicornis, Oithona plumifera, thermophilic species, that is, Penilia avirostris, and gelatinous zooplankton suggests a structural change in the Mondego plankton community. These results provide empirical support to the expectation that expanding climate variance changes plankton structure and functioning, likely fostering trophic interactions in pelagic food webs.
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  • 85
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    Intra-population variability of ocean acidification impacts on the physiology of Baltic blue mussels (Mytilus edulis): integrating tissue and organism response (2017)
    Springer
    In:  Journal of Comparative Physiology B - Biochemical Systemic and Environmental Physiology, 187 (4). pp. 529-543.
    Details
    Publikationsdatum: 2020-02-06
    Beschreibung: Increased maintenance costs at cellular, and consequently organism level, are thought to be involved in shaping the sensitivity of marine calcifiers to ocean acidification (OA). Yet, knowledge of the capacity of marine calcifiers to undergo metabolic adaptation is sparse. In Kiel Fjord, blue mussels thrive despite periodically high seawater PCO2, making this population interesting for studying metabolic adaptation under OA. Consequently, we conducted a multi-generation experiment and compared physiological responses of F1 mussels from ‘tolerant’ and ‘sensitive’ families exposed to OA for 1 year. Family classifications were based on larval survival; tolerant families settled at all PCO2 levels (700, 1120, 2400 µatm) while sensitive families did not settle at the highest PCO2 (≥99.8% mortality). We found similar filtration rates between family types at the control and intermediate PCO2 level. However, at 2400 µatm, filtration and metabolic scope of gill tissue decreased in tolerant families, indicating functional limitations at the tissue level. Routine metabolic rates (RMR) and summed tissue respiration (gill and outer mantle tissue) of tolerant families were increased at intermediate PCO2, indicating elevated cellular homeostatic costs in various tissues. By contrast, OA did not affect tissue and routine metabolism of sensitive families. However, tolerant mussels were characterised by lower RMR at control PCO2 than sensitive families, which had variable RMR. This might provide the energetic scope to cover increased energetic demands under OA, highlighting the importance of analysing intra-population variability. The mechanisms shaping such difference in RMR and scope, and thus species’ adaptation potential, remain to be identified.
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  • 86
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    The biology of Isancistrum subulatae n.sp., a monogenean parasitic on the squid, Alloteuthis subulata, at Plymouth (1984)
    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 64 (02). pp. 285-302.
    Details
    Publikationsdatum: 2020-07-16
    Beschreibung: A new species of a monogenean Isancistrum subulatae (Gyrodactylidae) has been discovered on the arms and tentacles of the cephalopod mollusc Alloteuthis subulata at Plymouth and I. loliginis, on the gills of the same host, has been re-discovered for the first time since its original description in 1912. I. subulatae, like other gyrodactylids, is viviparous, and has been shown by experiments to transfer to new hosts by contagion. In nature such transfers probably take place during copulation of the hosts and since the parasite may occur in numbers of several thousands per host, it may thereby constitute a venereal disease.
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  • 87
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    Challenges and strategies for the visual exploration of complex environmental data (2017)
    Taylor & Francis
    In:  International Journal of Digital Earth, 10 (10). pp. 1070-1076.
    Details
    Publikationsdatum: 2020-02-06
    Beschreibung: In this opinion paper, we, a group of scientists from environmental-, geo-, ocean- and information science, argue visual data exploration should become a common analytics approach in Earth system science due to its potential for analysis and interpretation of large and complex spatio-temporal data. We discuss the challenges that appear such as synthesis of heterogeneous data from various sources, reducing the amount of information and facilitating multidisciplinary, collaborative research. We argue that to fully exploit the potential of visual data exploration, several bottlenecks and challenges have to be addressed: providing an efficient data management and an integrated modular workflow, developing and applying suitable visual exploration concepts and methods with the help of effective and tailored tools as well as generating and raising the awareness of visual data exploration and education. We are convinced visual data exploration is worth the effort since it significantly facilitates insight into environmental data and derivation of knowledge from it.
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  • 88
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    Optimisation of fucoxanthin extraction from Irish seaweeds by response surface methodology (2017)
    Springer
    In:  Journal of Applied Phycology, 29 (2). pp. 1027-1036.
    Details
    Publikationsdatum: 2020-02-06
    Beschreibung: Fucoxanthin is a xanthophyll pigment which occurs in marine brown algae (Phaeophyceae). The anti-diabetic, anti-obesity, anti-cancer, and antioxidant properties of fucoxanthin have been widely reported. Macroalgae, particularly brown seaweeds, grow prolifically around Irish coasts, representing a valuable resource of nutraceuticals such as fucoxanthin for functional food applications. The aim of this study was to maximise the solvent extraction yield from three anatomically discrete regions of the seaweed thallus: blade, stipe, and holdfast. Response surface methodology was applied to determine optimum parameters for extraction of fucoxanthin from the seaweed, Fucus vesiculosus, as a model species. A central composite design was applied with four extraction variables: time (30–70 min), temperature (30–70 °C), solvent pH (5.0–9.0), and percentage acetone (30–70 %). Fucoxanthin content of extracts was quantified by high-performance liquid chromatography. Percentage acetone was found to have the most significant (P = 0.0002) effect on fucoxanthin yield, followed by pH (P = 0.028) and temperature (P = 0.049). Multiple response optimisation determined that fucoxanthin yield from F. vesiculosus may be maximised by incubating at 30.0 °C for 36.5 min, pH 5.7, with 62.2 % acetone. Optimised responses were applied to a further nine brown seaweeds; Alaria esculenta, Ascophyllum nodosum, Fucus serratus, Himanthalia elongata, Laminaria digitata, Laminaria hyperborea, Pelvetia canaliculata, Saccharina latissima, and Saccorhiza polyschides. In all species, the blades contained significantly more fucoxanthin than stipes, while holdfasts contained the least. Alaria esculenta blade had the greatest yield (0.870 mg g−1 dry mass), followed by F. vesiculosus blade (0.699 mg g−1) and L. digitata blade (0.650 mg g−1).
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  • 89
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    Minireview: algal natural compounds and extracts as antifoulants (2018)
    Springer
    In:  Journal of Applied Phycology, 30 (3). pp. 1859-1874.
    Details
    Publikationsdatum: 2021-02-08
    Beschreibung: Marine biofouling is a paramount phenomenon in the marine environment and causes serious problems to maritime industries worldwide. Marine algae are known to produce a wide variety of chemical compounds with antibacterial, antifungal, antialgal, and anti-macrofouling properties, inhibiting the settlement and growth of other marine fouling organisms. Significant investigations and progress have been made in this field in the last two decades and several antifouling extracts and compounds have been isolated from micro- and macroalgae. In this minireview, we have summarized and evaluated antifouling compounds isolated and identified from macroalgae and microalgae between January 2010 and June 2016. Future directions for their commercialization through metabolic engineering and industrial scale up have been discussed. Upon comparing biogeographical regions, investigations from Southeast Asian waters were found to be rather scarce. Thus, we have also discussed the need to conduct more chemical ecology based research in relatively less explored areas with high algal biodiversity like Southeast Asia.
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  • 90
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    Role of the Foredune in Controlling Barrier Island Response to Sea Level Rise (2018)
    Springer
    In:  In: Barrier Dynamics and Response to Changing Climate. , ed. by Moore, L. and Murray, A. Springer, Cham, pp. 175-207.
    Details
    Publikationsdatum: 2018-01-22
    Beschreibung: The height, volume, and alongshore extent of the foredune are primary controls on the response of barrier islands to the elevated storm surge that accompanies hurricanes and extra-tropical storms. In this respect, the ability of the foredune to recover following a storm determines whether a barrier island can maintain elevation as sea level rises and the island migrates landward through the redistribution of sediment to the back of the island through washover and breaching. This chapter provides a review of a body of recent fieldwork on the role of the foredune in controlling island transgression. It is argued that the role of the foredune to control washover and island transgression is analogous to that of a variable resistor in an electrical circuit, with the strength of the resistor dependent on the ability of the dune to recover in height and extent following each storm. Recovery of the foredune requires that sediment removed to the nearshore during a storm be returned to the beachface through the landward migration and welding of the innermost bars where it is eventually transported to the backshore and trapped by vegetation. Field observations from Padre Island in Texas, Santa Rosa Island in Florida, and Assateague Island in Virginia suggest that the recovery of dune height can be modeled using a sigmoidal growth curve, and that recovery can take up to a decade. The slow rate of dune recovery suggests that the resiliency of barrier islands to sea level rise is dependent on whether there is a change in the frequency and magnitude of storm events or an interruption to the exchange of sediment among the nearshore, beach, and dune. Ultimately, the height and volume of the foredune can be controlled by the framework geology (to varying degrees), which determines beach and nearshore state through the availability and texture of sediment and structural controls. In this respect, the response of barrier islands to sea level rise can be expected to vary regionally and alongshore as a reflection of diverse framework geology. The local response to sea level rise depends on the ability of the dune to recover following storms. Assuming no new sediment from alongshore or offshore sources, an increase in the frequency of washover will limit the ability of the dune to recover, and recent field evidence suggests that a change in dune height and volume is self-reinforcing, which suggests a lack of island resiliency. Further testing is required to determine how the field observations and modeling described in this chapter from a select group of barrier islands around the United States are applicable to other islands and consistent throughout the evolution of a barrier island.
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  • 91
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    Biology and Ecology of Radiolaria (2015)
    Springer
    In:  In: Marine Protists. , ed. by Ohtsuka, S., Suzaki, T., Horiguchi, T., Suzuki, N. and Not, F. Springer, Tokyo, pp. 179-222.
    Details
    Publikationsdatum: 2018-03-23
    Beschreibung: Radiolaria are unicellular holoplanktonic protozoa with siliceous or strontium sulfate skeletons. Mainly studied by micropaleontologists because of their excellent fossil record, they are also key members of planktonic communities and play important roles in various oceanic ecosystems. This chapter presents an overview of the current knowledge on living Radiolaria (orders Acantharia, Collodaria, Nassellaria, Spumellaria and Taxopodia). Besides general considerations on Radiolaria as a whole, it focuses on the taxonomy, biology, and ecology of each radiolarian order. Finally this chapter provides insights on research perspectives to improve our knowledge of living radiolarians and their ecological role in marine ecosystems.
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  • 92
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    Determination of Soil Parameters to Analyze Mechanical Behavior Using Lade's Double-Surface Work-Hardening Model (2016)
    Taylor & Francis
    In:  Marine Georesources & Geotechnology, 34 (5). pp. 465-473.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: In this study, Lade's double-surface work-hardening constitutive model was adopted which uses the elasto-plasticity model as a basic conceptual framework. The model can analyze work hardening and work softening of nonlinear stress-strain behavior, and is regarded as superior to other elasto-plasticity constitutive models in terms of estimation. In the double-surface work-hardening constitutive model, 14 soil parameters are needed to estimate soil behaviors. To determine them, laboratory tests—isotropical consolidation test and conventional compression test—were conducted. Determining of soil parameters is highly complicated and time-consuming; randomness cannot be ruled out in determining parameters that are sensitive to stress-strain estimation, and error may occur. For this reason, a linear and nonlinear regression analysis was used to determine soil parameters. In estimation of undrained behavior, the estimated stress-strain behavior based on the two constitutive models largely overlapped with the test results. However, in estimating drained behavior, the outcome of the two models and the test results were mostly the same, but between the two models, the double-surface work-hardening constitutive model had a sharper slope in initial stress state, and a smaller maximum deviatoric stress.
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  • 93
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    Die Ergochrome (Physiologie, Isolierung, Struktur und Biosynthese) (1973)
    Springer
    In:  Fortschritte der Chemie organischer Naturstoffe, 30 . pp. 151-206.
    Details
    Publikationsdatum: 2018-04-11
    Beschreibung: Mutterkorn, das Dauermycel des auf Roggenähren wuchernden Fadenpilzes Claviceps purpurea, enthält eine Gruppe hellgelber, schwach saurer, optisch aktiver Farbstoffe. Obwohl die ersten Präparate dieser Farbstoffe schon vor fast 100 Jahren von DRAGENDORFF und Mitarb. (14) isoliert wurden, konnte deren Strukturaufklärung im wesentlichen erst in den letzten Jahren durchgeführt werden. Dies ist darauf zurückzuführen, daß für die Reindarstellung der schwer trennbaren, teilweise diastereomeren Farbstoffe leistungsfähige chromatographische Methoden entwickelt werden mußten (1, 27, 29, 47). Als sich gezeigt hatte, daß diese Farbstoffe eine Naturstoffgruppe aus mehr als 10 Vertretern mit sehr ähnlichen Strukturen bilden, wurde für sie der Sammelname Ergochrome und eine einfache Nomenklatur vorgeschlagen (19, 25, 29).
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  • 94
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    A palaeoecological review of the lower Gatun Formation (Miocene) of Panama with special emphasis on trophic relationships (2018)
    Springer
    In:  Palaeobiodiversity and Palaeoenvironments, 98 (4). pp. 571-591.
    Details
    Publikationsdatum: 2021-02-08
    Beschreibung: A thorough literature review in combination with an analysis of fossil material from collections enables a detailed reconstruction of the ecosystem of the lower Gatun Formation (Serravallian to Tortonian; late middle to early late Miocene) of Central Panama. The fossil record is highly diverse and includes foraminifers, sponges, corals, mollusks, polychaetes, crustaceans, bryozoans, echinoderms, and vertebrates. The fauna indicates fully marine conditions in a shallow basin with a soft, stable substrate and mostly low water energy. The benthic life is dominated by suspension-feeding bivalves and carnivores including mainly gastropods and crustaceans. Herbivores are strikingly rare. Predator-prey relationships can be directly inferred from abundant drill holes in mollusk shells caused by naticid and muricid gastropods showing strong prey selectivity. Additionally, deep and narrow incisions at the outer lip of the apertures of gastropod shells are reported for the first time and proposed to be caused by crustaceans. Investigating the life habits of the benthic organisms revealed a moderate tiering of the fauna and the importance of empty shells as habitats for a variety of taxa. The nektonic life is highly diverse including nautilids, fishes, rays, sharks, sea turtles, crocodiles, and toothed whales. An analysis of the food preferences of the fossil fauna enables the reconstruction of a trophic web for the ecosystem of the lower Gatun Formation.
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  • 95
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    Coordination in a diphyid siphonophore (1983)
    Taylor & Francis
    In:  Marine Behaviour and Physiology, 9 (2). pp. 139-170.
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    Publikationsdatum: 2018-05-22
    Beschreibung: The behaviour of Chelophyes has been analysed from the point of view of coordination between stem and nectophores, and an electron microscope study of the effectors and conducting elements has been carried out. Coordination between the stem and anterior nectophore involves two pathways, one epithelial and the other nervous. The nervous link consists of a bundle of small neurites and a single giant axon. There is some evidence that this mediates rapid escape behaviour. After the nerves have been cut, coordination is maintained via the epithelial route. Impulses can jump from epithelial cells into nerves but the transmission process is unclear. Neuro‐epithelial transmission involves conventional synapses. As in physonectid siphonophores, the stem has two nervous systems each with its own giant fibre, and a slow system, the endodermal epithelium. In the nectophore, marginal nerve centres generate a swimming rhythm. Conduction in the subumbrellar muscle is myoid. The exumbrellar epithelium and the subumbrellar endoderm are conducting tissues. Histological study reveals synapses in the predicted locations and gives details of myo‐epithelial organization and nervous layout. Novel histological features include elements resembling steroid‐secreting cells, which ensheath nerves and are innervated by them, and innervated giant non‐nervous cells lying between the nerve ring and the hydroecium. The subumbrellar muscle cells are shown to have sarcolemmal invaginations reminiscent of the f‐tubule system of vertebrate muscle.
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  • 96
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    Heat challenges can enhance population tolerance to thermal stress in mussels: a potential mechanism by which ship transport can increase species invasiveness (2018)
    Springer
    In:  Biological Invasions, 20 (11). pp. 3107-3122.
    Details
    Publikationsdatum: 2021-02-08
    Beschreibung: It is unclear whether transport by human vectors can increase the robustness of translocated populations and thereby enhance their invasiveness. To test this concept, we investigated the effect of heat stress on the tolerance of mussel populations towards a second stress event of the same kind. The heat challenges we mimicked can be faced by marine invertebrates that are transported through regions with high sea surface temperatures on ship hulls or in ballast water tanks. The study included 5 mussel species that were collected at sites in Brazil, Chile, Finland, Germany (Baltic Sea) and Portugal. In parallel laboratory experiments, monospecific groups of individuals were exposed to heat challenges that caused 60–83% mortality in the experimental groups within 15–28 days. The surviving individuals were exposed to a second stress event of the same kind, while their survival was then compared to the robustness of conspecifics that had not been exposed to elevated temperatures before. We observed that thermal tolerance was significantly enhanced by previous heat stress experience in case of Semimytilus algosus from Chile and in case of Mytilus edulis from Germany. Our results suggest that heat challenges, which marine invertebrates experience during transport, can enhance stress tolerance in founder populations of these species in their non-native range by potentially increasing the frequency of genetically adapted genotypes. This points at the necessity to learn more about selection acting on organisms during human-mediated transport—in the aquatic but also in the terrestrial environment.
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  • 97
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    Microbial community composition and trophic role along a marked salinity gradient in Laguna Puilar, Salar de Atacama, Chile (2018)
    Springer
    In:  Antonie van Leeuwenhoek International Journal of General and Molecular Microbiology, 111 (8). pp. 1361-1374.
    Details
    Publikationsdatum: 2021-02-08
    Beschreibung: The geological, hydrological and microbiological features of the Salar de Atacama, the most extensive evaporitic sedimentary basin in the Atacama Desert of northern Chile, have been extensively studied. In contrast, relatively little attention has been paid to the composition and roles of microbial communities in hypersaline lakes which are a unique feature in the Salar. In the present study biochemical, chemical and molecular biological tools were used to determine the composition and roles of microbial communities in water, microbial mats and sediments along a marked salinity gradient in Laguna Puilar which is located in the “Los Flamencos” National Reserve. The bacterial communities at the sampling sites were dominated by members of the phyla Bacteroidetes, Chloroflexi, Cyanobacteria and Proteobacteria. Stable isotope and fatty acid analyses revealed marked variability in the composition of microbial mats at different sampling sites both horizontally (at different sites) and vertically (in the different layers). The Laguna Puilar was shown to be a microbially dominated ecosystem in which more than 60% of the fatty acids at particular sites are of bacterial origin. Our pioneering studies also suggest that the energy budgets of avian consumers (three flamingo species) and dominant invertebrates (amphipods and gastropods) use minerals as a source of energy and nutrients. Overall, the results of this study support the view that the Salar de Atacama is a heterogeneous and fragile ecosystem where small changes in environmental conditions may alter the balance of microbial communities with possible consequences at different trophic levels.
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  • 98
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    The Changing Face of Reef Building (2016)
    Springer
    In:  In: Coral Reefs at the Crossroads. , ed. by Hubbard, D. K., Rogers, C. S., Lipps, J. H. and Stanley, G. D. Coral Reefs of the World, 6 . Springer, Dordrecht, pp. 127-153. ISBN 978-94-017-7567-0
    Details
    Publikationsdatum: 2017-03-22
    Materialart: Book chapter , NonPeerReviewed
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  • 99
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    On the controversy about South African pelagic fisheries: comment on the Letter to the Editor by de Villiers (this issue) (2017)
    Springer
    In:  Marine Biology, 164 (1). Art. No. 14.
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    Publikationsdatum: 2016-12-19
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  • 100
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    Initialization shock in decadal hindcasts due to errors in wind stress over the tropical Pacific (2017)
    Springer
    In:  Climate Dynamics, 49 (7-8). pp. 2685-2693.
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    Publikationsdatum: 2020-02-06
    Beschreibung: Low prediction skill in the tropical Pacific is a common problem in decadal prediction systems, especially for lead years 2–5 which, in many systems, is lower than in uninitialized experiments. On the other hand, the tropical Pacific is of almost worldwide climate relevance through its teleconnections with other tropical and extratropical regions and also of importance for global mean temperature. Understanding the causes of the reduced prediction skill is thus of major interest for decadal climate predictions. We look into the problem of reduced prediction skill by analyzing the Max Planck Institute Earth System Model (MPI-ESM) decadal hindcasts for the fifth phase of the Climate Model Intercomparison Project and performing a sensitivity experiment in which hindcasts are initialized from a model run forced only by surface wind stress. In both systems, sea surface temperature variability in the tropical Pacific is successfully initialized, but most skill is lost at lead years 2–5. Utilizing the sensitivity experiment enables us to pin down the reason for the reduced prediction skill in MPI-ESM to errors in wind stress used for the initialization. A spurious trend in the wind stress forcing displaces the equatorial thermocline in MPI-ESM unrealistically. When the climate model is then switched into its forecast mode, the recovery process triggers artificial El Niño and La Niña events at the surface. Our results demonstrate the importance of realistic wind stress products for the initialization of decadal predictions
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