RS is grateful to the Alexander von Humboldt foundation for granting a postdoctoral fellowship. We acknowledge the Institute del Mar del Peru (IMARPE) and the joint IMARPE-IRD projects PALEOTRACES and DISCOH for the support of this research. We also acknowledge the program CIENCIACTIVA that granted the research of climate change impacts on the upwelling ecosystem in the frame of the Master's Program in Marine Sciences at the Universidad Peruana Cayetano Heredia. This study was supported by the German Research Foundation through Sonderforschungsbereich 754 ("ClimateBiogeochemistry Interactions in the Tropical Ocean"). SEM observations were performed at the ALYSES facility (IRD, Sorbonne University, supported by grants from Region Ile-de-France). We deeply thank Bo Thamdrup, chief scientist of the Galathea-3 expedition (Leg 14), and Bente Lomstein, who conducted the core sampling onboard t...

Subsurface water masses with permanent oxygen deficiency (oxygen minimum zones,OMZ) are typically associated with upwelling regions and exhibit a high sensitivity to climate variability. Over the last decade, several studies have reported a global ocean deoxygenation trend since 1960 and a consequent OMZ expansion.

The research was granted by the ‘Cátedra CONCYTEC en Ciencias del Mar’, sponsored by the Peruvian National Council of Science and Technology and the Universidad Peruana Cayetano Heredia, Master Program of Marine Sciences, and by the Peruvian Marine Research Institute (IMARPE) project INIOX. It was also supported by collaborative projects between the Institut de la Recherche pour le Développement (IRD) and IMARPE: LMI DISCOH and Chaire Croisée PROSUR.

Durante la ocurrencia de El Niño Costero 2017, en la bahía del Callao se instalaron dos trampas de sedimento (mecánica y automática) a 30 y 40 m de profundidad para obtener muestras e información de los flujos de material particulado en el subsistema bentónico. La trampa mecánica (30 m) registró acumulación equivalente a 6,46 cm/año; la automática, entre el 20 y 29 de marzo 2017, recolectó 8.777,9 mg.m-2día-1, asociados a las máximas descargas del río Rímac. En el área somera, donde estuvieron las trampas, y en la plataforma continental adyacente (96 m de profundidad) testigos de sedimentos no perturbados (recolectados entre 2017 y 2018) se destinaron para determinar i) el contenido orgánico del primer centímetro superficial del sedimento durante y después de los máximos aportes fluviales del río a la bahía y, ii) los cambios en la estructura sedimentaria así como...

This study was supported by IMARPE(Peru), the research unit LOCEAN‐IPSL (UMR 7192 CNRS/IRD/UPMC/MNHN) in France and the projects JEAI MIXPALEO,PALEOPECES, PALEOTRACES, DISCOH, PCCC and the‘CátedraCONCYTEC en Ciencias del Mar’. We thank Jorge Vasquez (JPL) for pro-viding the 4km resolution GHRSST‐PP SST data and David Correa forperforming the objective interpolation of these data. Finally, we thankFrancisco Chavez and Monique Messié, with whom we sustained sounddiscussions that helped us for the preparation of this paper.