ABSTRACTS

Oral Session 8 | Wednesday, October 5, 15:00–15:20 | Abstract 668

Carbon export in a tropical ecosystem: The Red Sea

We investigated the export of the organic carbon driven by mesoscale features (i.e., fronts and eddies) in the Red Sea waters, one of the warmest sea of the global ocean, to evaluate the contribution of the eddy subduction pump in such ecosystem. We mainly focused on a mesoscale front at the eddy edge, identified from satellite and Seaglider survey. The physical and biogeochemical structure of the front was characterized using a bio-optical profiler equipped with a CTD and bio-optical sensors revealing a subducted filament with biological tracers reaching up to 400 m depth. In parallel, water sampling within and outside of the subducted filament were taken. Measurements from these water samples include the biogeochemical composition of the subducted water, allowing us to better understand and characterize the export potential of the subducted filament. Intrusion of particulate organic carbon was ranging from 12 to 45 mg C m^–3, and was approximately found within the isopycnal layer 28 – 28.35 kg m^–3. The concomitant high values in chlorophyll a suggest subduction of viable phytoplankton within this isopycnal layer. The AOU values associated to the subduction of POC suggest high rates of particles remineralization by bacteria reflective of the presence of fresh and labile carbon material. Characterizing the properties of the subducted filament in such ecosystem (i.e., low oxygen and high temperature) will contribute to our understanding of such event in the context of climate change.

Malika Kheireddine, King Abdullah University of Sciences and Technology, 0000-0002-2726-5426

Mustapha Ouhssain, King Abdullah University of Sciences and Technology

Burton Jones, King Abdullah University of Sciences and Technology