Connectivity patterns among coral reef systems in the southern Gulf of Mexico

Abstract

This study simulated the connectivity patterns among 7 coral reef systems in the southern Gulf of Mexico. Two subgroups of reefs were considered: one near the mainland over the narrow western shelf, and the other over the wide Campeche Bank (CB). A particle-tracking module was coupled to a realistic simulation with the Hybrid Coordinate Ocean Model in order to study the transport and dispersion of particles in near surface waters. The simulation consisted of the launch of 100 passive particles (virtual larvae) from each reef, every 24 h over a 5 year period; it considered species lasting up to 35 d in the plankton and assumed no seasonality in reproduction. On the western shelf, connection was northwards from March to August, and southwards from September to February; over the CB edge, the connection was northwestwards throughout the year. Over the western shelf, reefs showed a strong degree of interconnectivity and high particle retention. Higher self-recruitment was most likely due to the passage of synoptic-scale atmospheric systems and their associated changes in wind and current direction. In contrast, CB reefs exhibited lower connectivity and less larval retention. Over the western edge of the Bank, connectivity was almost unidirectional because of the influence of the cyclonic gyre in the Campeche Bay, which causes particles to disperse over a wide area with low probabilities of selfrecruitment. The main connection pathway was the confluence zone between neritic and oceanic waters over the outer shelf of the Bank. Connection between the 2 groups of reefs was weak. © Inter-Research 2014.