PhD thesis defense - Viviane David

Date de publication : Dec 12, 2019 2:54:2 PM

Viviane David obtained the title of Doctor of Sciences on december 11th at AgroParisTech in Paris. The title of her thesis was “Understanding and predicting effects of chemicals on population dynamics of three-spined stickleback in mesocosms".

Summary:

In ecotoxicology, experiments in artificial ecosystems (mesocosms) are of a great interest because they allow to evaluate the direct and indirect effects of toxicants at different levels of biological organization such as individuals, populations and ecosystems. However, mesocosm experiments are characterized by a low statistical power and a high risk of not detecting differences between control (without contaminant) and contaminated mesocosms when there is one. In this context, individual-based models based on the dynamic energy budget theory have been suggested as relevant tools to improve the analysis of mesocosm experiment results. Thus, the objective of this phD was to develop an individual-based model simulating the three-spined stickleback population dynamics in artificial streams. The knowledge on the biological model used, the three-spined stickleback, as well as the use of several available datasets from mesocosm experiments with or without tested chemicals allowed us to develop this model. Our individual-based model was first developed, calibrated and evaluated on data from three-spined stickleback population dynamics in mesocosms in control conditions. In a second step, the model was applied to several case studies where different chemical substances were tested in mesocosms. Simulation results have shown that the individual-based modelling approach seems promising for improving current assessments of the effects of chemicals. Indeed, our model helped us to have a better understanding of the modes of action of toxicants and a relevant extrapolation of ecotoxicity data measured in the laboratory on organisms to the population level.