Seasonal surface connectivity in the Gulf of California

A three-dimensional numerical model is used to study seasonal connectivity in the Gulf of California. From the Eulerian velocity fields of the model, particle trajectories were calculated for the 12 months of the year using an advection/diffusion scheme. Connectivity was quantified for twelve Gulf provinces with different dynamic/circulation characteristics being defined by the Eulerian velocity field: strong or weak coastal currents, eddies, and areas of mixing and exchange. Retention occurred for 9–12 months of the year in the Upper Gulf, Eddy and Sonora regions of the northern Gulf because of the Gulf-wide eddy circulation, which implies high potential for the auto-recruitment of larvae in this province. High retention was also found on the peninsula side of the southern Gulf in association with weaker residual currents, again implying potential for self-recruitment. In contrast, low retention was observed on the mainland side of the central and southern Gulf, from which particles are exported to many areas by the faster residual currents enhancing the potential for recruitment of distant coastal species. Empirical Orthogonal Function analyses revealed a strong annual and semiannual evolution in accordance with the strong seasonality of the Gulf dynamics.