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  • 1
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    Coupling of oceanic carbon and nitrogen facilitates spatially resolved quantitative reconstruction of nitrate inventories (2018)
    Nature Research
    In:  Nature Communications, 9 (Article number 1217).
    Details
    Publication Date: 2021-03-19
    Description: Anthropogenic impacts are perturbing the global nitrogen cycle via warming effects and pollutant sources such as chemical fertilizers and burning of fossil fuels. Understanding controls on past nitrogen inventories might improve predictions for future global biogeochemical cycling. Here we show the quantitative reconstruction of deglacial bottom water nitrate concentrations from intermediate depths of the Peruvian upwelling region, using foraminiferal pore density. Deglacial nitrate concentrations correlate strongly with downcore δ13C, consistent with modern water column observations in the intermediate Pacific, facilitating the use of δ13C records as a paleo-nitrate-proxy at intermediate depths and suggesting that the carbon and nitrogen cycles were closely coupled throughout the last deglaciation in the Peruvian upwelling region. Combining the pore density and intermediate Pacific δ13C records shows an elevated nitrate inventory of 〉10% during the Last Glacial Maximum relative to the Holocene, consistent with a δ13C-based and δ15N-based 3D ocean biogeochemical model and previous box modeling studies.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: text
    DOI: 10.1038/s41467-018-03647-5
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Simulated leakage of high pCO2 water negatively impacts bivalve dominated infaunal communities from the Western Baltic Sea (2016)
    Nature Research
    In:  Scientific Reports, 6 . p. 31447.
    Details
    Publication Date: 2020-06-18
    Description: Carbon capture and storage is promoted as a mitigation method counteracting the increase of atmospheric CO2 levels. However, at this stage, environmental consequences of potential CO2 leakage from sub-seabed storage sites are still largely unknown. In a 3-month-long mesocosm experiment, this study assessed the impact of elevated pCO2 levels (1,500 to 24,400 μatm) on Cerastoderma edule dominated benthic communities from the Baltic Sea. Mortality of C. edule was significantly increased in the highest treatment (24,400 μatm) and exceeded 50%. Furthermore, mortality of small size classes (0–1 cm) was significantly increased in treatment levels ≥6,600 μatm. First signs of external shell dissolution became visible at ≥1,500 μatm, holes were observed at 〉6,600 μatm. C. edule body condition decreased significantly at all treatment levels (1,500–24,400 μatm). Dominant meiofauna taxa remained unaffected in abundance. Densities of calcifying meiofauna taxa (i.e. Gastropoda and Ostracoda) decreased in high CO2 treatments (〉6,600 μatm), while the non - calcifying Gastrotricha significantly increased in abundance at 24,400 μatm. In addition, microbial community composition was altered at the highest pCO2 level. We conclude that strong CO2 leakage can alter benthic infauna community composition at multiple trophic levels, likely due to high mortality of the dominant macrofauna species C. edule.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: text
    DOI: 10.1038/srep31447
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Mandibular gnathobases of marine planktonic copepods – feeding tools with complex micro- and nanoscale composite architectures (2015)
    Beilstein-Institut
    In:  Beilstein Journal of Nanotechnology, 6 (1). pp. 674-685.
    Details
    Publication Date: 2017-04-13
    Description: Copepods are dominant members of the marine zooplankton. Their diets often comprise large proportions of diatom taxa whose silicified frustules are mechanically stable and offer protection against grazers. Despite of this protection, many copepod species are able to efficiently break even the most stable frustule types. This ability requires specific feeding tools with mechanically adapted architectures, compositions and properties. When ingesting food, the copepods use the gnathobases of their mandibles to grab and, if necessary, crush and mince the food items. The morphology of these gnathobases is related to the diets of the copepods. Gnathobases of copepod species that mainly feed on phytoplankton feature compact and stable tooth-like structures, so-called teeth. In several copepod species these gnathobase teeth have been found to contain silica. Recent studies revealed that the siliceous teeth are complex microscale composites with silica-containing cap-like structures located on chitinous exoskeleton sockets that are connected with rubber-like bearings formed by structures with high proportions of the soft and elastic protein resilin. In addition, the silica-containing cap-like structures exhibit a nanoscale composite architecture. They contain some amorphous silica and large proportions of the crystalline silica type α-cristobalite and are pervaded by a fine chitinous fibre network that very likely serves as a scaffold during the silicification process. All these intricate composite structures are assumed to be the result of a coevolution between the copepod gnathobases and diatom frustules in an evolutionary arms race. The composites very likely increase both the performance of the siliceous teeth and their resistance to mechanical damage, and it is conceivable that their development has favoured the copepods’ dominance of the marine zooplankton observed today.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.3762/bjnano.6.68
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Microbial nucleation of Mg-rich dolomite in exopolymeric substances under anoxic modern seawater salinity: New insight into an old enigma (2012)
    GSA (Geological Society of America)
    In:  Geology, 40 (7). pp. 587-590.
    Details
    Publication Date: 2019-10-24
    Description: Sulfate-reducing bacteria are known to mediate dolomite formation under hypersaline conditions, but details of the crystal nucleation process are still poorly constrained. Our laboratory study demonstrates for the first time that Desulfobulbus mediterraneus, a marine sulfate-reducing bacterium, mediates primary precipitation of Mg-rich dolomite under anoxic conditions in media replicating modern seawater chemistry at low temperature (21 °C). Precipitation of crystals was associated with extracellular polymeric substances in a monospecific biofilm, providing templates for nucleation by altering the molar Mg/Ca ratio. After initial nucleation of single nanospherulites (∼50 nm), growth was mediated by aggregation, resulting in spherulites of ∼2–3 μm in diameter. Nucleation led to differences in Mg/Ca ratios and δ44/40Ca values among the organic material (i.e., biofilm including cells and extracellular polymeric substances; 0.87 ± 0.01 [2 SD] and 0.48‰ ± 0.11‰ [2 SE], respectively), the crystals (1.02 ± 0.11 [2 SD] and 〈−0.08‰ ± 0.24‰ [2 SE], respectively), and the liquid bulk medium after mineral precipitation (4.53 ± 0.04 [2 SD] and 1.10‰ ± 0.24‰ [2 SE], respectively). These data indicate a two-step fractionation process involved in the sequestration of Ca from the solution into the crystal lattice of the mineral precipitated. Our results demonstrate the capability of extracellular polymeric substances to overcome kinetic inhibition, fostering the formation of kinetically less favorable Mg-rich dolomite, and they also question the applicability of the Ca isotopic system as a proxy for paleogeochemistry of seawater.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    DOI: 10.1130/G32923.1
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Food Supply and Seawater pCO2 Impact Calcification and Internal Shell Dissolution in the Blue Mussel Mytilus edulis (2011)
    Public Library of Science
    In:  PLoS ONE, 6 (9). e24223.
    Details
    Publication Date: 2018-01-22
    Description: Progressive ocean acidification due to anthropogenic CO2 emissions will alter marine ecosytem processes. Calcifying organisms might be particularly vulnerable to these alterations in the speciation of the marine carbonate system. While previous research efforts have mainly focused on external dissolution of shells in seawater under saturated with respect to calcium carbonate, the internal shell interface might be more vulnerable to acidification. In the case of the blue mussel Mytilus edulis, high body fluid pCO2 causes low pH and low carbonate concentrations in the extrapallial fluid, which is in direct contact with the inner shell surface. In order to test whether elevated seawater pCO2 impacts calcification and inner shell surface integrity we exposed Baltic M. edulis to four different seawater pCO2 (39, 142, 240, 405 Pa) and two food algae (310–350 cells mL−1 vs. 1600–2000 cells mL−1) concentrations for a period of seven weeks during winter (5°C). We found that low food algae concentrations and high pCO2 values each significantly decreased shell length growth. Internal shell surface corrosion of nacreous ( = aragonite) layers was documented via stereomicroscopy and SEM at the two highest pCO2 treatments in the high food group, while it was found in all treatments in the low food group. Both factors, food and pCO2, significantly influenced the magnitude of inner shell surface dissolution. Our findings illustrate for the first time that integrity of inner shell surfaces is tightly coupled to the animals' energy budget under conditions of CO2 stress. It is likely that under food limited conditions, energy is allocated to more vital processes (e.g. somatic mass maintenance) instead of shell conservation. It is evident from our results that mussels exert significant biological control over the structural integrity of their inner shell surfaces.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1371/journal.pone.0024223
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Microbial colonization and degradation of polyethylene and biodegradable plastic bags in temperate fine-grained organic-rich marine sediments (2016)
    Elsevier
    In:  Marine Pollution Bulletin, 103 (1-2). pp. 168-178.
    Details
    Publication Date: 2019-09-23
    Description: Highlights • Polypropylene and biodegradable plastic bags were incubated in marine sediments. • Bacterial colonization was highest on biodegradable plastic bags. • None of the two bag types showed signs of degradation after 98 days. • Marine sediments probably represent a long-term sink for both types of litter. Abstract To date, the longevity of plastic litter at the sea floor is poorly constrained. The present study compares colonization and biodegradation of plastic bags by aerobic and anaerobic benthic microbes in temperate fine-grained organic-rich marine sediments. Samples of polyethylene and biodegradable plastic carrier bags were incubated in natural oxic and anoxic sediments from Eckernförde Bay (Western Baltic Sea) for 98 days. Analyses included (1) microbial colonization rates on the bags, (2) examination of the surface structure, wettability, and chemistry, and (3) mass loss of the samples during incubation. On average, biodegradable plastic bags were colonized five times higher by aerobic and eight times higher by anaerobic microbes than polyethylene bags. Both types of bags showed no sign of biodegradation during this study. Therefore, marine sediment in temperate coastal zones may represent a long-term sink for plastic litter and also supposedly compostable material.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.marpolbul.2015.12.024
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
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    New insights into the complex architecture of siliceous copepod teeth (2015)
    Elsevier
    In:  Zoology, 118 (3). pp. 141-146.
    Details
    Publication Date: 2017-04-12
    Description: Copepods belong to the dominant marine zooplankton taxa and play an important role in particle and energy fluxes of the marine water column. Their mandibular gnathobases possess tooth-like structures, so-called teeth. In species feeding on large proportions of diatoms these teeth often contain silica, which is very probably the result of a coevolution with the siliceous diatom frustules. Detailed knowledge of the morphology and composition of the siliceous teeth is essential for understanding their functioning and their significance in the context of feeding interactions between copepods and diatoms. Based on analyses of the gnathobases of the Antarctic copepod Rhincalanus gigas, the present study clearly shows, for the first time, that the silica in the siliceous teeth features large proportions of crystalline silica that is consistent with the mineral α-cristobalite and is doped with aluminium. The siliceous structures have internal chitinous fibre networks, which are assumed to serve as scaffolds during the silicification process. The compact siliceous teeth of R. gigas are accompanied by structures with large proportions of the elastic protein resilin, likely reducing the mechanical damage of the teeth when the copepods feed on diatoms with very stable frustules. The results indicate that the coevolution with diatom frustules has resulted in gnathobases exhibiting highly sophisticated composite structures.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.zool.2014.11.001
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 8
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    Mg-dolomite nucleation in biofi lm of sulfate-reducing bacteria at modern seawater salinity (2012)
    In:  [Talk] In: Goldschmidt Conference 2012, 24.-29.06.2012, Montreal, Canada .
    Details
    Publication Date: 2013-01-17
    Type: Conference or Workshop Item , NonPeerReviewed
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    OceanRep: Talk
  • 9
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    Biomimetics : a million ideas from the ocean (2011)
    Cluster of Excellence "The Future Ocean"
    In:  In: The Ocean Is Our Future : Kiel Marine Scientists On a Time Trip To 2100. Cluster of Excellence "The Future Ocean", Kiel, pp. 70-75. ISBN 978-3-00-036928-5
    Details
    Publication Date: 2012-02-29
    Description: "Biomimetics reinforces the need to protect ocean biodiversity, the patent library for the technologies of the future." Stanislav N. Gorb
    Type: Book chapter , NonPeerReviewed
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    OceanRep: Book chapter
  • 10
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    Element Partitioning in Brachiopods – Implications for Proxy Use and Biomineralisation (2019)
    In:  [Talk] In: Goldschmidt Conference 2019, 18.-23.08.2019, Barcelona, Spain .
    Details
    Publication Date: 2019-10-28
    Type: Conference or Workshop Item , NonPeerReviewed
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    OceanRep: Talk
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