Ocean Deoxygenation Conference | Kiel 2018

Multiproxy paleoenvironmental reconstructions are crucial in order to improve our understanding of the nutrient rich, high productivity environments, such as the Peruvian upwelling system, in relation with the currently changing climate. In this study we present compilation of multiproxy results focusing on the relationship between benthic and pelagic environment in relation with a strong oxygen minimum zone (OMZ) over the last 25 thousand years. The sediment core M77/2-52-2 was obtained from the northern part of the Peruvian continental slope from 1250 m water depth outside the main OMZ. We combined results of surface productivity indicators such as organic carbon and biogenic opal as well as isotope applications together with the diol upwelling index and biomarkers to decipher the changes in phytoplankton community in the surface ocean. The information from the deep ocean was gathered through benthic foraminifera and their relationship with oxygen and nitrate availability. In addition, we applied three independent biomarker-based SST proxies (UK37, TEXH86, LDI) to investigate SSTs and the response of these proxies to upwelling and oxygen dynamics. Overall, the surface productivity was lower during the Last Glacial Maximum and gradually increased during the deglaciation causing bottom water deoxygenation indicated by both benthic foraminifera and δ15Nsed results. Organic SST proxies and biomarkers, together with biogenic silica and δ 30Sidiatom revealed a potential influence of upwelling strength and nutrient availability on these SST proxies and phytoplankton community changes.