ABSTRACT
A number of water circulation processes generate patchiness, the dominant feature of coral reef oceanography. The lateral trapping phenomenon controls the shelf-scale dispersion processes in the Great Barrier Reef matrix. It operates at tidal frequency with the formation of eddies in the lee of coral reefs and islands. Free-shear layers are a common sight around reefs during periods of strong tidal currents, even in the absence of density stratification. The key finding is that near headlands and coral reefs, the patterns of transport and dispersion vary greatly over short-length scales and do not display the smearing tendency of a typical diffusive process. Small waves breaking on an emerged reef generate an undertow along the sloping surface of the reef. At some distance, the undertow is balanced by the surface wave- and wind-driven current toward the wall.
