PhD-position: “To determine the consequences of large-scale sand extractions on the North Sea” – Deadline 20 August 2022

The department of Estuarine & Delta Systems (EDS – location Yerseke) is looking for a highly motivated PhD student with a background in marine ecology and numerical modelling. You will work on the consequences of large-scale sand extractions from the North Sea on primary production and secondary producers, via their impact on fine suspended sediments and biogeochemistry.

THE PROJECT

Sand extraction from the North Sea is expected to increase drastically for future infrastructure projects and coastal protection by sand nourishments. Large-scale marine sand extraction has important ecosystem effects, amongst others by changing the physical (e.g. turbulence and turbidity) and biogeochemical (e.g. nutrient availability) conditions that will propagate through the whole marine food web. Within the recently awarded project ‘ORELSE’ (Operational Recommendations for Ecosystem-based Large-scale Sand Extraction), a Dutch consortium will give recommendations for an ecosystem-based large-scale sand-extraction approach in the Dutch North Sea.

The main approach of the NIOZ-led work package of the ‘ORELSE’ project, consisting of a PhD and a postdoc study, will be to translate laboratory-based experiments into novel mathematical descriptions for upscaling and predictions using physical-ecological coupled models. Phytoplankton (microscopic floating algae) is the basis of the marine food web and their abundance and production is controlled by physical conditions (e.g. light, turbidity and turbulence), nutrient availability and grazing. The main phytoplankton grazer is zooplankton, which constitutes an important trophic link between algae and fish. While good model descriptions for phytoplankton exist, current models of zooplankton growth and grazing behaviour typically assume no dependency on turbulence and turbidity, which probably does exist.

The PhD-student will perform experiments in the laboratory on how zooplankton-phytoplankton (feeding) interactions depend on turbulence, silt concentration, and algal physiological conditions and will use the data to parameterise physiologically-based (DEB) model(s) of zooplankton dynamics. The new model descriptions will be applied in several idealized physical settings to predict how sand extraction, simulated by various nutrient conditions, hydrodynamic regimes, and turbidity, will affect phytoplankton and zooplankton dynamics.

THE VACANCY

The PhD-project is at the interface of marine ecology and numerical modelling. On the one hand, you will setup and run laboratory experiments with phyto- and zooplankton, sort zooplankton under the microscope, work in the analytical laboratory and interpret results in the context of zooplankton dynamics. When possible, we will also encourage you to join expeditions with research vessels to the North Sea to gain field experience. On the other hand, you will translate the experimental results into mathematical descriptions and run numerical simulations. The PhD candidate will be based at EDS (Yerseke), but we foresee regular visits to COS (Texel) to facilitate the knowledge exchange with the post-doc and supervisors.