We already know that local environmental conditions are a significant factor affecting bleaching severity and recovery after bleaching: reefs that are near upwellings, or experience cooler currents or wind mixing, tend to experience less severe bleaching, and those with few other pressures tend to recover better. Could science-based localised interventions that mimic these natural stress-reducing phenomena (for example by incrementally increasing water movement, reducing water temperature by 1-2°C, or disrupting the water’s surface) reduce coral stress, bleaching severity and/or promote recovery on key reef sites, potentially providing time and space for natural acclimatization and adaptation processes to occur?

After a worldwide search for the right technology to mix and cool water on the Great Barrier Reef, we found it right here in Queensland. WEARS Australia’s ReefMixes are solar-powered, low-energy, don’t introduce contaminants into the water and be able to withstand ocean conditions.

Focusing on a specific 1 km2 reef tourism site on Moore Reef near Cairns, we assembled the best-available observational data to inform hydrodynamic modelling of conditions at this site during the 2017 coral bleaching event. Preliminary computational fluid dynamic modelling indicates that under doldrum conditions similar to those observed in Feb-Mar 2017, deployment of pods of ReefMixers could restore flow and achieve localised reductions in temperature. Use of real-time in-water sensor networks and methods to measure temperature, flow and coral stress at the site will enable rapid evaluation of effectiveness of the engineering intervention and, importantly, provide a world-first in-situ research platform for the study of factors encouraging coral reef adaptation to and recovery from climate stress in the real world.