148-14 Benthic Foraminiferal Responses to Organic Carbon Flux Across Glacial-Interglacial Cycles at IODP Site 1588

Session: Insights from Microfossils and Their Modern Analogs: From Traditional to Emerging Approaches (Posters)

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Understanding how organic carbon is exported to the deep sea is important for reconstructing benthic ecosystem dynamics and carbon cycling during the Quaternary period. Benthic foraminifera, ubiquitous marine protozoa with a calcareous test, are highly responsive to variations in organic matter flux, oxygen availability, and water mass properties like temperature and salinity, making them a valuable proxy for tracking changes in environmental conditions. By identifying which taxa dominate under different flux regimes and how assemblage structure varies across depth intervals, benthic foraminifera offer a window into the spatial heterogeneity of deep sea carbon delivery during major climate transitions. This study investigates benthic foraminiferal assemblages from IODP Site U1588 (21°54.99′N, 20°19.99′W; 1339 m deep). At site U1588, Mediterranean Outflow Water (MOW) intersects the slope at intermediate depth, directly influencing bottom water oxygenation, salinity, and organic carbon supply. MOW’s core depth shifts across glacial and interglacial cycles, allowing this site to provide a sensitive record of how changes in intermediate water mass structure shape benthic community composition and carbon transfer to the seafloor. We present data from benthic foraminiferal assemblages at Site U1588 spanning the past ~600,000 years, focusing on key glacial and interglacial transitions including Marine Isotope Stage 12 to 11, Stage 8 to 7, and Stage 2 to 1. Here we test the hypothesis that specific taxa are consistently associated with elevated export production and these associations intensify during interglacial periods, potentially reflecting enhanced surface productivity or the shoaling of nutrient-rich intermediate waters. Preliminary results suggest that glacial assemblages preceding the transition are characterized by species indicate of environments with plentiful export of fresh organic matter whereas interglacial assemblages after the transition are dominated by species typical of suboxic environments with more refractory organic matter. Future work will integrate data from the nearby abyssal site U1587 (~3479 m depth) to evaluate whether the benthic foraminiferal responses to organic carbon flux observed at U1588 extend into the abyssal realm, where flux is lower, faunal turnover may be reduced, and bottom water conditions are shaped by the influence of Antarctic Bottom Water. Together, these sites form a depth transect to test how water mass structure and carbon delivery shape benthic ecosystem responses to orbital climate forcing.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10750

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