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Célia Santos

Institution:University of Bremen
Room:GEO, room 1410
Phone:+49 421 218 - 65075
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PhD project:

Marine primary productivity during the Mid-Pleistocene Transition off the Western Iberian Margin: a perspective from diatoms and diatom specific biomarkers

Coastal upwelling regions, as the Iberian margin, are highly productive and play an important role in the Earth’s climate. Thus, the reconstruction of coastal primary productivity is a crucial parameter in paleoclimate research.

Diatoms, the dominant phytoplankton class in those systems, are robust paleoceanographic and paleoproductivity tracers. Despite diatom high abundance in the water column, they are frequently affected by dissolution and their sedimentary record is discontinuous. Lipid biomarkers are also affected by diagenesis leading to better preservation at conditions of high accumulation rates and low oxygen concentrations in bottom and pore waters. Their preservation may thus be enhanced under different conditions that that of the diatoms.

To date studies have demonstrated that diatoms, as a group, do not produce a specific diagnostic organic marker. This project will investigate the main diatom species in upwelling regions, aiming to identify a common organic lipid signature. If successful, this will allow the reconstruction of past primary productivity in areas where diatoms are not preserved in the sediments. Another objective of this project is to investigate the changes in primary productivity (PP) and paleooceanographic conditions during the Mid-Pleistocene Transition using IODP Exp339 sites U1385 and U1391 retrieved from the Iberian margin.

The Mid-Pleistocene Transition (MPT, ~ 1250 – 700 ka) is the major climatic transition during the Quaternary and reflects a shift from a dominant periodicity of 41 kyr to 100 kyr in glacial/interglacial oscillations, without substantial changes in orbital parameters. The mechanisms behind the MPT remain a matter of debate, as well as the marine ecosystem changes and PP variability during this period.

This PhD project is collaboratively conducted under the scope of the DiatBio project (both funded by the Portuguese Science Foundation - FCT) which aims to investigate primary productivity and climate variability during the Mid-Pleistocene Transition (MPT) off Sines (Iberian Margin).

Thesis committee:

Prof. Dr. Gesine Mollenhauer Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research (AWI), Bremerhaven
Dr. Enno Schefuß University of Bremen
Prof. Dr. Fátima Abrantes Instituto Português do Mar e da Atmosfera (IPMA), Portugal