PhD student: Elise VISSENAEKENS (2019-2021)

Supervisor (ASR): Katell Guizien

General information:
Ecological connectivity is an emerging property of ecosystems that allows the maintenance and dissemination of species within a biogeographic region and the resilience of their populations to local disturbances. This ecological connectivity occurs for most marine species by dispersal of the larval stage by currents and currently studied by two approaches, by the analysis of population genetics and by the biophysical simulation of larval transport (Guizien et al., 2006 ; 2012). The latter approach makes it possible to explore the potential ecological connectivity between existing populations, such as genetic methods, but also to or from potential habitats that a species could colonize in a changing context. Thus, the biophysical simulation approach of ecological connectivity is of major interest for maritime spatial planning due to its ability to anticipate changes in the distribution of habitats in the current context of ocean circulation but also in the context of its future development.
A prerequisite for the biophysical simulation of ecological connectivity is to rely on simulations of reliable marine circulation at spatial and temporal scales influencing the connectivity of populations. For spatial scales, this involves describing the currents at scales of around one hundred meters around populations to properly describe retention and at hundreds of kilometers to describe the connections between populations. For the time scales, it is a question of taking into account the meteorological variability, the episodes of reproduction being often fleeting. The SYMPHONIE model makes it possible, thanks to a curvilinear dipolar grid, to carry out such simulations but it is now necessary to validate them. The objective of this thesis is to establish validated reference simulations of high-resolution circulation, along the coasts and in the canyons of the Gulf of Lions, in the current and future context. The first step will be to evaluate, in the face of current observations, the reliability of simulations carried out in the Gulf of Lion on a curvilinear grid (Briton et al., in press; resolution of 80 m around Cap de Creus and 2.7 km above the abyssal plain) over the period 2009-2013. All the current data available (SAVED database, CASCADE campaigns, CRUMED mooring, campaigns
LATEX) will be used for this evaluation. The second step will consist in carrying out simulations for the period 2090-2095 on the same spatial model and using the same climatic forcings as those used by Hermann et al. (2008) for a future regional simulation in the Gulf of Lion. The evaluation of the impact of the spatial resolution will be made by comparison with this regional simulation.