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

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If you have a question about this talk, please contact Oscar Branson.

This is a hybrid event. The talk will be given via Zoom (https://zoom.us/j/99984123581), and screened live in the Tilley Lecture Theatre.

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.

This talk is part of the Department of Earth Sciences Seminars (downtown) series.

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