The hydrodynamic regime at John Brewer Reef, Great Barrier Reef

Full description

An array of current meters and tide gauges was deployed around John Brewer Reef between March and September 1987. Moorings were located to allow recording of data from the far field and near field of John Brewer Reef. These measurements were used to provide boundary conditions and test the accuracy of the numerical model of circulation around the reef.The model boundary was defined by CM1, CM2, CM3, CM4, CM5 and CM13. However, the current meters attached to moorings CM5 (deployed 2/4/87) and CM13 (deployed 1/4/87) were not recovered. Mooring CM4 (deployed 2/4/87) drifted to the Whitsunday Islands. The current meter was badly fouled and the data were unusable.The locations for moorings CM6, CM7, CM8 and CM12 were chosen on the basis of results from a complementary project, where numerical models of hydrodynamics and dispersion were used to simulate the wind, tidal, long-period current and wave circulation around GBR reefs, for examination of dispersal of larvae of the crown-of-thorns starfish.The transect CM3, CM8 and CM9 was laid to investigate the interaction between John Brewer Reef and Lodestone Reef. These reefs are only 7km apart and by studying both reefs at the same time it was possible to consider inter-reefal recruitment of crown-of-thorns starfish as well as self-seeding. The current meter attached to mooring CM9 (deployed 3/4/87) was not recovered.Tide gauges were placed at the corners of the model (moorings CM1, CM2, CM4 and TG1) and in the centre of the model, close to John Brewer Reef (TG2). The mooring CM1 drifted from its original position and only data up to the 27/5/87 are considered reliable. Mooring CM4 drifted to the Whitsunday Islands and the data were not considered reliable. The tide gauge (TG2) was placed near the reef to monitor any tidal differences between the reef and the adjacent deep water.The study utilized ancillary data from a wind gauge placed in the lagoon of John Brewer Reef by AIMS and wind data from Cairns, Cardwell, Townsville and Mackay supplied by the Bureau of Meteorology.
The aim of this project was to collect field data to calibrate a numerical model for the combined tidal and wind-forced circulation at John Brewer Reef, and to apply those circulation patterns to calculate the trajectories, residence times and likelihood of outbreaks of crown-of-thorns starfish on areas of the reef.

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Maintenance and Update Frequency: notPlanned

Statement: Statement: Several current meter moorings were vandalised or accidentally trawled during deployment. Current meter data were not usable from stations CM4, CM5, CM9 and CM13. However, the amount of reliable data retrieved from other stations was sufficient to allow the currents near John Brewer Reef to be modelled.The timing of the field work did not coincide with the crown-of-thorns starfish spawning season. However, it was thought that the results from the model would provide a basis for estimating the likelihood of larval retention during the spawning season, should current meter data become available.

Notes

Credit
Andrews, John C, Dr (Principal Investigator)

Credit
Steinberg, Craig R, Mr (Custodian)