Abstract
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.
| Original language | English |
|---|---|
| Pages (from-to) | 1350-1367 |
| Number of pages | 18 |
| Journal | Paleoceanography |
| Volume | 31 |
| Issue number | 10 |
| DOIs | |
| Publication status | Published - 1 Oct 2016 |
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Environmental constraints on Holocene cold-water coral reef growth off Norway : Insights from a multiproxy approach. / Raddatz, Jacek; Liebetrau, Volker; Trotter, Julie; Rüggeberg, Andres; Flögel, Sascha; Dullo, Wolf Christian; Eisenhauer, Anton; Voigt, Silke; McCulloch, Malcolm.
In: Paleoceanography, Vol. 31, No. 10, 01.10.2016, p. 1350-1367.Research output: Contribution to journal › Article
TY - JOUR
T1 - Environmental constraints on Holocene cold-water coral reef growth off Norway
T2 - Insights from a multiproxy approach
AU - Raddatz, Jacek
AU - Liebetrau, Volker
AU - Trotter, Julie
AU - Rüggeberg, Andres
AU - Flögel, Sascha
AU - Dullo, Wolf Christian
AU - Eisenhauer, Anton
AU - Voigt, Silke
AU - McCulloch, Malcolm
PY - 2016/10/1
Y1 - 2016/10/1
N2 - 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.
AB - 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.
KW - boron isotopes
KW - cold-water corals
KW - Holocene
KW - Li/Mg
KW - Lophelia pertusa
KW - pH upregulation
UR - http://www.scopus.com/inward/record.url?scp=84991517863&partnerID=8YFLogxK
U2 - 10.1002/2016PA002974
DO - 10.1002/2016PA002974
M3 - Article
VL - 31
SP - 1350
EP - 1367
JO - Paleoceanography
JF - Paleoceanography
SN - 0883-8305
IS - 10
ER -