Some aspects of lagoon sedimentation and circulation at One Tree Reef, Southern Great Barrier Reef

UnknownObservations of water movement at One Tree Reef under modal wind, wave, and tide conditions show that the lagoon currents are insufficient to entrain lagoon sediments and cannot account for the windward to leeward decrease in sediment size across the lagoon. Bioturbation may suspend bottom material long enough for it to be transported a short distance by the ambient current, depending on the grain size and current velocity. In addition, low-frequency, high-energy events largely produce the same southeast to northwest movement of water observed under modal energy conditions and would be responsible for transporting and sorting large volumes of sediment over a short period. Patch reefs locally supply significant amounts of sediment directly to the lagoon, resulting in a local increase in sediment size and a characteristic build-up of material and extension of patch reefs to leeward. These observations are directly applicable to other reefs with well-developed lagoons in the southern Great Barrier Reef and may also apply to similar reefs in other parts of the Great Barrier Reef