Linking surface and deep-ocean ecosystem dynamics across the mid-Brunhes at the Iberian Margin

How paleoceanographic changes modulated the influence of surface primary production on deep-ocean settings at the Iberian Margin remains a matter of debate. Here, we address this question for the mid-Brunhes interval by integrating high-resolution micropaleontological records of calcifying phytoplankton with a suite of surface and deep-ocean geochemical proxies, as well as a detailed assessment of ichnological content, sediment colour, and bioturbation. These analyses are based on the Atlantic Iberian Margin sedimentary core IODP Site U1385. Our data indicate that the transfer of organic matter from the surface ocean to the seafloor was strongly modulated by both orbital- and suborbital-scale paleoclimate variability during Marine Isotope Stages (MIS) 12 to 9 (~450–339 ka). Variations in assemblage composition and abundance of calcareous nannofossil and ichnological characterization, together with changes in sediment composition, suggest that surface ocean conditions and production patterns were not always recorded in the deep-ocean environment. The sensitive response of macrobenthic tracemaker communities, coupled with variable sedimentary characteristics, highlights the influence of bottom-water conditions and ventilation on organic matter preservation and benthic ecosystem dynamics. These findings underscore the importance of integrating multiproxy records to achieve a more comprehensive understanding of paleoclimate and paleoceanographically-driven surface to deep-ocean coupling.