"As simple as possible: a modelling approach to upscale the relevance of ecotoxicological studies.A big discrepancy exists between the increasing demand for ecological realism in regulatory risk assessment and the effective implementation of ecotoxicological studies aimed at assessing the adverse effect of stressors at the population or higher level. The effect of toxicants is commonly measured on individuals as a proxy for the effect on populations but the actual population level impacts are very hard to determine. Ecological modelling can overcome this challenge. However, until now the complexity in the application of these models has presented a serious hurdle for their use in ecotoxicology.In this study we propose the application of a simple generic toxicokinetic-toxicodynamic model that integrates life-history traits such as growth, reproduction, maintenance and survival in one model organism to assess adverse effects of three different metals over time. We will carry out experiments to calibrate and test the model. The calibration of the model will allow the identification of the physiological modes of action of each metal, unraveling the different ways the chemicals can affect the life-cycle of the organism. We will improve the predictive and diagnostic power of these models by direct measurements of the time course of internal metal concentrations which will replace the currently used “scaled internal concentrations”, a very indirect approximation. Finally, we will couple the toxicokinetic-toxicodynamic model with an individual-based population model and explore the population level consequences of metal contamination.This research will provide insight into the physiological modes of action of three metals at individual level and their population level consequences in an ecological context. We will demonstrate how effects of different chemical stressors can be understood, modeled and assessed within one simple, but generic modelling framework."