Ecological variability at the Drake Passage over the last 200 ka glacial-interglacial intervals

The Antarctic Circumpolar Current (ACC) flows through the Drake Passage (DP), influencing global oceanic circulation and climate. However, there is a notable gap in understanding ecological responses to variability in ACC strength and to terrigenous flux driven by the melting of the Patagonian Ice Sheet (PIS). Hence, this research aims to assess the palaeoecological changes at the DP over the last 200 ka. The palaeoecological changes are reconstructed using planktic and benthic foraminifera abundance at International Ocean Discovery Programme Site U1544. Before that the age model was constrained using sortable silt plus fine sand size fraction (SSFS; 10–125 µm), along with a couple of 14C ages and a diatom biomarker ( Hemidiscus karstenii ) and compared with published-dated SSFS data from the DP and LR04 benthic stacks. Neogloboquadrina pachyderma was the dominant species during Marine Isotope Stage (MIS) 6 and 4, and bottom water was relatively oxic during MIS 6, as indicated by a higher abundance of Cibicides spp. The deglaciation is marked by a higher abundance of Turborotalita quinqueloba , suggesting reduced salinity due to the melting of PIS. The bottom water was suboxic during deglaciation, as indicated by peaks in Melonis spp. and Fursenkoina spp. The interglacial MIS 5 and 3 have enhanced primary productivity and marked the higher abundance of planktic foraminifera Globigerina spp. along with other warm water species and benthic foraminifera, Uvigerina spp. This study suggests that ACC and PIS melting control ecological variability at DP.