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.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: coral; foraminifera; Drake Passage; deglacial; Antarctic; Southern Ocean; The Antarctic; Antarc*; Sea ice
• Online Access: https://hdl.handle.net/1983/31d0240d-9520-4c20-91f9-9deab762f989; https://research-information.bris.ac.uk/en/publications/31d0240d-9520-4c20-91f9-9deab762f989; https://doi.org/10.1029/2021PA004288; https://research-information.bris.ac.uk/ws/files/299437688/Stewart_et_al._2021_ACR_PA004288.pdf

Abstract 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 reexpansion 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 multifaunal 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 (a) a northward migration of food supply (primary production) into the sub-Antarctic Zone and (b) poorly oxygenated seawater at depth during this Antarctic cooling interval.