Thursday June 23, 5pm CEST

Peter D. NOOTEBOOM^1,2*

The journey of sinking marine microplankton and its implication for palaeoceanographic reconstructions

¹ Department of Physics, Institute for Marine and Atmospheric Research Utrecht (IMAU), Utrecht University, Utrecht, Netherlands
² Centre for Complex Systems Studies, Utrecht University, Utrecht, Netherlands
^* p.d.nooteboom@uu.com

A primary part of the Earth's archive to reconstruct past climates is provided by marine sediments, consisting of (fossil remains from) microplankton. The microplankton species in the bottom sediments originated from a location close to the ocean surface before they started sinking to the bottom. Hence, microplankton at the ocean bottom is representative of the ocean surface environment and can be used for palaeoceanographic reconstructions. It is often assumed that these planktonic species sunk vertically downwards. However, the microplankton is transported laterally by ocean currents during its sinking journey.

Here we model the transport of dinoflagellate cysts (dinocysts) during their sinking journey in global high-resolution (0.1˚ horizontally) model simulations of the present-day and middle-late Eocene oceans. We investigate the implications of their lateral displacement on the interpretation of sedimentary dinocyst data when these are used for palaeoceanographic reconstructions.
For example, if subtropical microplankton species are found near Antarctica in a specific time period, two hypotheses can be tested with this method: (a) the ocean near Antarctica had subtropical temperatures, or (b) Antarctica was not subtropical, but the microplankton were transported laterally by ocean currents and originated from another region with subtropical temperatures.