Ocean circulation, larval retention, and connectivity among coral populations on the Northwest Shelf of Australia

The Northwest Shelf of Australia is one of the source regions of the Leeuwin Current, a poleward flowing eastern boundary current in the south-east Indian Ocean. The region also features a number of significant marine reserves... [ view full abstract ]

The Northwest Shelf of Australia is one of the source regions of the Leeuwin Current, a poleward flowing eastern boundary current in the south-east Indian Ocean. The region also features a number of significant marine reserves and fisheries resources closely juxtaposed with an increasing number of oil and gas facilities as well as growing shipping traffic servicing onshore mining facilities.The shelf circulation on the Northwest Shelf is dominated by the southward flowing Holloway Current that feeds into the Leeuwin Current during the austral autumn and winter; and by the Australian monsoonal wind-driven currents during the austral summer. Tidal currents, tropical cyclones, and Madden-Julian Oscillation are also important factors in driving horizontal and vertical mixing processes on the shelf and in the nearshore environment.

In this study, we use the Rutgers version of the Regional Ocean Modelling System, a 3-dimensional, hydrostatic, primitive equations model, to simulate the shelf circulation of the north-west shelf at 1 km resolution. The model is initialized with temperature and salinity values from the Ocean Forecasting Australia Model and forced by OFAM 3-hourly meteorological forcing and open boundary condition and delivers hourly model outputs during 2003-2010. The tidal currents generated in the model has been assessed by comparison with current measurements from the Integrated Marine Observing System (IMOS) shelf moorings in the region. The model outputs are used to assess the seasonal variations of shelf currents, their interactions with coastal and island features, and the regional connectivity among coral reefs along the coast.