Immediate climate action is essential to preserve reef systems globally, but recent coral bleaching events indicate that the Great Barrier Reef (GBR) is already under serious threat. Bleaching interventions will be required to offer relief and allow time for coral regeneration and adaptation [1].
Shading has been shown to reduce coral bleaching severity and thermal stress [2], however installing artificial shading over entire reefs is logistically challenging. One promising alternative involves generating low-lying fog plumes to attenuate the downwelling sunlight. This method is best suited to the low wind speeds observed during doldrum conditions, where low cloudiness and oceanic mixing rates put coral at particular risk of bleaching.
A small prototype fog sprayer was acquired, capable of pumping high-pressure seawater through an array of misting nozzles. Preliminary trials were carried out in late 2021, involving two deployments within a sheltered soccer field in Brisbane and in-situ over Big Broadhurst Reef on the GBR. Both cases demonstrated successful generation of low-lying plumes with mean dry particle diameters of 120 nm, capable of scattering UV and visible light. Preliminary results from the marine deployment suggest that shading of up to 16 % was achieved beneath the plume.