Postdoc position: “Forage fish; Extending ecosystem models with sandeel to capture spatial-temporal dynamic feedback mechanisms”.

We offer a position of 3 years to investigate, by developing and using coupled hydrodynamics-ecosystem models, the full feedback between sandeel (Ammodytes spp) and its environment, i.e. habitat, predation and food. We anticipate to elucidate sandeel-zooplankton dynamics (food) in relation to its value and importance as food organism for higher trophic levels (birds, seals).

The postdoc will implement sandeel biology and productivity in the ERSEM-BFM ecosystem model, using results from other parts of the project. Implementation will be done in a 1D model version, and the postdoc will use a 3D application to the north-west European continental shelf to run a 10-year hindcast of physical, biogeochemical and ecological variables, including sandeel biomass. The results will be analysed for inter-annual variability and driving factors influencing the sandeel population. A sensitivity study will be carried out to further understanding of selected driving factors for the carrying capacity for the sandeel population. This will be inspired by and cross-compared with results obtained with other models used in the project. The postdoc will publish the work in 3-4 peer-reviewed journal papers. The preferred start date is 1 January 2022.

The work will be carried out under the supervision of dr. Johan van der Molen , and is part of a wider project that includes observations and links to seal populations and includes collaborations with Wageningen Marine Research, University of Wageningen, Rijkswaterstaat, Cefas and the University of St. Andrews.

The Project
The growing human population requires sustainable food and energy supply, which puts pressure on the marine environment. This will influence primary and secondary production and propagate up through the food web to higher trophic levels. In the North Sea, the key link between planktonic production and top predators are the so-called forage fish, including herring, sprat, and sandeel.

This vacancy is part of a wider project that studies the importance of sandeels as forage fish for top predators, and focusses on the factors which determine the occurrence and production of sandeel.

Extensive anthropogenic developments are planned for the southern North Sea including offshore windfarms and seaweed-farms, and proposed sites often coincide with major sandeel habitats. The project studies how sandeel distribution is shaped by abiotic covariates (sediment, depth and temperature), food availability (zooplankton production) and predator distributions. These relationships will be simulated using an integrated population - dynamic energy budget model and with a 3D ecosystem model (ERSEM-BFM) aiming at scenario simulation to illustrate how lower-level changes in habitat and productivity might propagate to higher trophic levels.