Coral spawn and bathymetric slicks in Synthetic Aperture Radar (SAR) data from the Timor Sea, north‐west Australia

Abstract

Annular‐ to crescent‐shaped low backscatter SAR slicks over carbonate reefs and shoals in the Timor Sea that exhibit ‘feathering’, and within the coral spawning period for the region, are interpreted to be caused by a coral spawn event. This represents the first time that such an event has been interpreted through satellite remote sensing. Additionally, ocean current data and detailed swath bathymetry of the sea floor to the south‐east of the coral spawn slicks suggest that elongate repeating slicks in this area are related to current flow over submarine channels. Assessment of these slicks in association with ancillary data, such as bathymetry, current velocities, weather, and timing of SAR acquisition allow a more robust interpretation of their origins. Through differentiating coral spawn and bathymetric slicks from oil and other biological slicks in shallow carbonate systems, such as the Timor Sea, petroleum and environmental assessments for these areas can be improved.

Acknowledgements

The authors wish to thank Andrew Heyward (Australian Institute of Marine Science) and Chris Simpson (Western Australia Department of Conservation and Land Management) for their expert discussion regarding coral spawning. We also thank Shanti Reddy and Peter Harris (Geoscience Australia) and two anonymous external reviewers, whose helpful comments greatly improved the original manuscript. A.T.J., M.T., G.A.L., J.M.K., and C.J.S. publish with the permission of the Chief Executive Officer, Geoscience Australia.