Energy budgets in copepod population modelling – How much model complexity do we really need in environmental risk assessment?

In environmental risk assessment (ERA), we aim to determine (a) which concentration of a
chemical substance can harm ecosystems and (b) which concentration is likely to occur in these
ecosystems. Since the EU-regulation REACH came into force in 2016, manufacturers bear full
responsibility for the ERA of all chemicals used in their production lines.
Standardized laboratory tests are usually performed as a first step to evaluate a chemical’s toxic
potential. However, such tests often only consider effects on individuals while the true protection
goal of ERA is the population level. Population models can help to extrapolate individual level
effects to actual populations. This is highly welcomed by the chemical industry since it can
substitute laborious and costly population experiments to an enormous degree. However, there is
an ongoing debate on how much complexity is actually needed in population models to be useful
in ERA.
In my research I aim to answer this fundamental question. I will develop, calibrate and validate a
population model that is based on the state-of-the-art mechanistic concepts of energy budget
theory (DEB) and individual bases models (IBMs) as I hypothesize that this is the most appropriate
way to approach population dynamics under chemical stress. I will use the harpacticoid copepod
Nitocra spinipes as a model organism due to its previous history as a test species in ERA, its
handleability in the laboratory and the novelty of applying DEB to copepods.