Lagrangian tracking of key demersal species in the western Mediterranean Sea: a high-resolution model approach

In this study we explore the most frequent trajectories of relevant demersal species in the western Mediterranean Sea. In particular, we focus on the Ibiza Channel, a region characterized by the interaction of water masses with distinct properties and by an intense fishing activity. Demersal species are suposed to be in planktonic stage, thus they behave, almost, as passive particles, being driven by the dominant ocean currents. The origin of selected demersal species, their preferred water mass properties, and their temporal variability are evaluated with a set of 2D and 3D backward Lagrangian simulations performed over a high-resolution ocean model. The model we use is the IBI-MFC, part of the Copernicus catalogue with a spatial resolution of 1/36º and 50 vertical layers. Moreover, the Lagrangian tracking is done with OceanParcels software.

With the above approach we get the most probable pathways, and associated water mass characteristics, of those demersal species of interest. Besides, a detailed evaluation of simulated trajectories provides interesting insights on the spatial and temporal changes in the origin of demersal species weeks before they reach the Ibiza Channel. These results are especially important to stablish new biodiversity hotspots that should be protected, e.g., as
eggs and larvae exportation areas.