Numerical study of circulation, dispersion, and hydrodynamic connectivity of surface waters on the Belize shelf

Abstract

A nested grid ocean circulation modeling system is used to examine the circulation, dispersion, and hydrodynamic connectivity of surface waters on the Belizean shelf. The nested grid system consists of a coarse‐resolution (∼19 km) outer model of the western Caribbean Sea, an intermediate‐resolution (∼6 km) middle model of the southern Meso‐American Barrier Reef System (MBRS), and a fine‐resolution (∼2 km) inner model of the Belizean shelf. The nested system is forced by climatological monthly mean surface forcing and integrated over 5 years. The near‐surface circulation on the Belize shelf produced by the inner model is characterized by a strong and persistent northwestward flow as a direct influence of the Caribbean Current on the northwestern shelf and a weak and spatially variable flow on the inner and southern shelf. The monthly mean model currents are used to calculate retention and dispersion of conservative, near‐surface particles carried by the ocean currents. The near‐surface dispersion is relatively higher in areas seaward (east) of Lighthouse and Glovers Reef atolls and lower on the inner shelf, particularly within the Inner Channel and in the vicinity of South Water Cay. To examine hydrodynamic connectivity of reefs in the surface waters of the Belize shelf, we calculate upstream and downstream retention areas for coral reefs at Turneffe Islands and Glovers Reef atolls. The potential sources of passive, near‐surface particle supply reaching these two reef atolls within 30 days include both the shallow waters surrounding the two sites, the deep waters between them, and the coastal waters of the Bay Islands (Honduras). The 30‐day downstream retention areas of the Turneffe and Glovers Reef atolls cover the central and southern Belize shelf, respectively.