An individual-based model to describe a bullhead population dynamics including temperature variations

Global change could affect the structure and function of ecosystems in complex ways. In particular, gradual climate warming and fragmentation of ecosystem habitats are known to impact strongly on aquatic populations. To tackle this question we have developed a dedicated, stochastic, spatial, individual-based model of the global bullhead population dynamics at the river network scale taking into account the influence of annual mean temperature. This article focused on the model description and its validation with experimental field data. We introduced temperature fluctuations and their impact on various demographics traits, such as growth, reproduction and survival. Several effect submodels were defined to describe these relationships, leading to a set of 40 parameters. The model was written in C++, and provided several population characteristics, such as individual numbers per age-class and network compartment over the course of time. The results were compared to experimental field data, and the model robustness was validated by a complete sensitivity analysis based on a cluster analysis followed by a co-inertia analysis. The population dynamics appeared to be mainly conditioned by changes in temperature, which had a particularly great impact on the juvenile survival rate.