An algorithmic model for invasive species: Application to Caulerpa taxifolia (Vahl) C. Agardh development in the North-Western Mediterranean Sea

The purpose of the study is to evaluate the propagation of the green alga of tropical origin Caulerpa taxifolia (Vahl) C. Agardh in the north-western Mediterranean sea—introduced in 1984—by means of an algorithmic computer model. In order to take into account spatial interactions and anthropic dispersion or activities such as eradication and introduction of specific predators, the model is based on a coupling of a geographical information system (GIS) with a stochastic discrete event simulation. Even if the model has to cope with incomplete data and sampling difficulties encountered in the hostile environment of the sea, interesting calibration and validation procedures have been achieved, including spectral analysis of spatial simulation results. At this stage, the model seems capable of achieving a certain level of prediction: local pattern of expansion, increase of C. taxifolia biomass and covered surfaces, and invasive behaviour towards existing communities.