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Environmental constraints on Holocene cold‐water coral reef growth off Norway: Insights from a multiproxy approach

  • Raddatz, Jacek Goethe University Frankfurt, Institute of Geosciences, Frankfurt am Main, Germany - GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany
  • Liebetrau, Volker GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany
  • Trotter, Julie The UWA Oceans Institute and School of Earth and Environment, University of Western Australia, Crawley, Australia
  • Rüggeberg, Andres Renard Centre of Marine Geology, Department of Geology and Soil Sciences, Ghent University, Belgium - Department of Geosciences, University of Fribourg, Switzerland
  • Flögel, Sascha GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany
  • Dullo, Wolf-Christian GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany
  • Eisenhauer, Anton GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany
  • Voigt, Silke Goethe University Frankfurt, Institute of Geosciences, Frankfurt am Main, Germany
  • McCulloch, Malcolm The UWA Oceans Institute and School of Earth and Environment, University of Western Australia, Crawley, Australia - ARC Centre of Excellence in Coral Reef Studies, University of Western Australia, Crawley, Australia
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    01.10.2016
Published in:
  • Paleoceanography. - 2016, vol. 31, no. 10, p. 1350–1367
cold-water corals
Lophelia pertusa
boron isotopes
Holocene
pH upregulation
Li/Mg
English High-latitude cold-water coral (CWC) reefs are particularly susceptible due to enhanced CO₂ uptake in these regions. Using precisely dated (U/Th) CWCs (Lophelia pertusa) retrieved during research cruise POS 391 (Lopphavet 70.6°N, Oslofjord 59°N) we applied boron isotopes (δ¹¹B), Ba/Ca, Li/Mg, and U/Ca ratios to reconstruct the environmental boundary conditions of CWC reef growth. The sedimentary record from these CWC reefs reveals a lack of corals between ~6.4 and 4.8 ka. The question remains if this phenomenon is related to changes in the carbonate system or other causes. The initial postglacial setting had elevated Ba/Ca ratios, indicative of meltwater fluxes showing a decreasing trend toward cessation at 6.4 ka with an oscillation pattern similar to continental glacier fluctuations. Downcore U/Ca ratios reveal an increasing trend, which is outside the range of modern U/Ca variability in L. pertusa, suggesting changes of seawater pH near 6.4 ka. The reconstructed bottom water temperature at Lopphavet reveals a striking similarity to Barent sea surface and subsea surface temperature records. We infer that meltwater pulses weakened the North Atlantic Current system, resulting in southward advances of cold and CO₂-rich Arctic waters. A corresponding shift in the δ¹¹B record from ~25.0‰ to ~27.0‰ probably implies enhanced pH up-regulation of the CWCs due to the higher pCO₂ concentrations of ambient seawater, which hastened mid-Holocene CWC reef decline on the Norwegian margin.
Faculty
Faculté des sciences et de médecine
Department
Département de Géosciences
Language
  • English
Classification
Ecology and biodeversity
License
License undefined
Identifiers
Persistent URL
https://folia.unifr.ch/unifr/documents/305505
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