Résumé
The Mediterranean spinous spider crab, Maja squinado (Herbst, 1788), plays a pivotal role in Mediterranean fisheries, significantly contributing to local economies and culinary traditions. While stocks have declined in some areas, others continue to support fishing activities despite declines. Understanding the species' demography is crucial for future management. A biophysical model was developed to explore the larval dispersion dynamics of M. squinado in the Mediterranean. This model incorporated data on the biology and ecology of the species, including larval duration and spawning habitats. The tool Ichthyop, designed to study ichthyoplankton dynamics, was used for simulations conducted from 2010 to 2020. These simulations were analyzed considering global surface water warming trends. The analysis generated maps illustrating trajectory density, system connectivity, and density and distance over time. Comparisons between scenarios highlighted the impact of environmental variations, identifying the Tunisia-Sardinia-Corsica complex as having strong connectivity, while the Balearic Islands remained isolated due to the crab's short pelagic larval duration (PLD). The study demonstrated the effectiveness of biophysical models in hypothesizing population declines in isolated areas and emphasized the importance of diverse modelling approaches at varying resolutions. Kernel density estimates (KDE) maps revealed interannual changes and temporal shifts in particle density, suggesting that global changes, including surface water warming, should be considered in future simulations to predict dispersal routes and connectivity more effectively in a changing Mediterranean.