Productivity and dissolved oxygen controls on the Southern Ocean deep‐sea benthos during the Antarctic Cold Reversal

• Published in: Paleoceanography and Paleoclimatology
• Main Authors: Stewart, Joseph A., Li, Tao, Spooner, Peter T., Burke, Andrea, Chen, Tianyu, Roberts, Jenny, Rae, James W. B., Peck, Victoria, Kender, Sev, Liu, Qian, Robinson, Laura F.
• Other Authors: NERC, University of St Andrews. School of Earth & Environmental Sciences, University of St Andrews. St Andrews Isotope Geochemistry, University of St Andrews. Centre for Energy Ethics
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: Coral; Foraminifera; Drake Passage; Deglacial; GC Oceanography; DAS; GC; Antarctic; Southern Ocean; The Antarctic; Antarc*; Sea ice
• Online Access: https://hdl.handle.net/10023/24176; https://doi.org/10.1029/2021pa004288

Funding was provided by an Antarctic Bursary awarded to J.A.S., ERC and NERC grants awarded to L.F.R. (278705, NE/S001743/1, NE/R005117/1) and L.F.R. and J.W.B.R. (NE/N003861/1). The Antarctic Cold Reversal (ACR; 14.7 to 13 thousand years ago; ka) phase of the last deglaciation saw a pause in the rise of atmospheric CO2 and Antarctic temperature, that contrasted with warming in the North. A re-expansion of sea ice and a northward shift in the position of the westerly winds in the Southern Ocean are well-documented, but the response of deep-sea biota and the primary drivers of habitat viability remain unclear. Here we present a new perspective on ecological changes in the deglacial Southern Ocean, including multi-faunal benthic assemblage (foraminifera and cold-water corals) and coral geochemical data (Ba/Ca and δ11B) from the Drake Passage. Our records show that, during the ACR, peak abundances of thick-walled benthic foraminifera Uvigerina bifurcata and corals are observed at shallow depths in the sub-Antarctic (∼300 m), while coral populations at greater depths and further south diminished. Our ecological and geochemical data indicate that habitat shifts were dictated by (i) a northward migration of food supply (primary production) into the Subantarctic Zone and (ii) poorly oxygenated seawater at depth during this Antarctic cooling interval. Peer reviewed