Sea level rise facilitates increased cross-reef transport at the reef-scale

An accurate representation of the effects of rising sea levels on coral reef hydrodynamics is crucial to examine retention and export mechanisms, highlight fine-scale ecological changes, and evaluate cross-reef transport. This study investigates how hydrodynamics are governed by rising sea levels within a coral reef atoll (One Tree Reef), located off the coast of Gladstone on the Southern Great Barrier Reef. By utilising present-day conditions and IPCC SSP scenarios, a Delft3D model was employed to simulate reef hydrodynamics under various sea level rise projections (28 cm and 101 cm). The model was validated against tidal gauges and field observational data. Depending on the phase of the tidal cycle, the results revealed a gradual decrease in ubot and an increase in velocity across OTR. Higher water levels lead to decreased wave forces especially towards the eastern reef crest; higher velocity intensifies eddies, and promotes transport of nutrients, sediment and larvae across the reef. This enhances turbidity, promotes algae growth, and may sweep larvae away from the reef prior to settlement. Continued sea level rise will further enhance these changes and processes experienced at finer scales will be altered or forced to adapt to remove possible reduction in the function of coral reef ecosystems.

Primary Presenter: Eleanor Mawson, The Lyell Centre, Heriot-Watt University, Edinburgh, Scotland, UK. (em2029@hw.ac.uk)

Authors:

Eleanor Mawson, Department of Energy, Geoscience, Instructure, and Society, The Lyell Centre, Heriot-Watt University, Edinburgh, EH14 4BA, United Kingdom.  (em2029@hw.ac.uk)

Michel Kaiser, Department of Energy, Geoscience, Instructure, and Society, The Lyell Centre, Heriot-Watt University, Edinburgh, EH14 4BA, United Kingdom.  (m.kaiser@hw.ac.uk)

Heidi Burdett, Umeå Marine Sciences Centre, Umeå University, Norrbyn 557, 905 71 Hörnefors, Sweden.  (heidi.burdett@umu.se)

Ian Parkins, IDOTP Consulting  (parkotron@gmail.com)

Andrew Johnson, MarFishEco, Fisheries Consultants, Edinburgh, London, United Kingdom, and Seattle, Washington, USA.  (andrew@marfisheco.com)

Marta Vallejo, Department of Mathematical and Computer Sciences, Heriot-Watt University, Edinburgh, EH14 4AP, United Kingdom.  (m.vallejo@hw.ac.uk)

Thomas Fellowes, Geocoastal Research Group and Marine Studies Institute, School of Geosciences, The University of Sydney, NSW, 2006, Australia.  (thomas.fellowes@sydney.edu.au)

Lachlan Perris, Geocoastal Research Group and Marine Studies Institute, School of Geosciences, The University of Sydney, NSW, 2006, Australia.  (lachlan.perris@sydney.edu.au)

Ana Vila-Concejo, Geocoastal Research Group and Marine Studies Institute, School of Geosciences, The University of Sydney, NSW, 2006, Australia.  (ana.vilaconcejo@sydney.edu.au)

David Woolf, International Centre for Island Technology, Heriot-Watt University, Orkney, KW16 3AN, United Kingdom.  (d.k.woolf@hw.ac.uk)

Jon Hill, Environment and Geography, The University of York, York, YO10 5DD, United Kingdom.  (jon.hill@york.ac.uk)