An empty sports field, a giant misting cannon and a drone saw QUT scientists test a natural and novel way to protect the Great Barrier Reef’s coral from bleaching, that's now expanded to real-world early testing from a scientific ship on the Reef.
- Early research trials have been conducted on the reef during calm, hot weather when coral is most at risk
- A fine mist of seawater spray over vulnerable Reef areas could shade coral
- New technique inspired by clouds’ ability to reflect sunlight
- Results from the recent trial are 'promising' with further analysis ahead of the AMSA conference in Cairns.
QUT atmospheric scientists Dr Joel Alroe and Professor Zoran Ristovski are lead researchers in the multidisciplinary research team, together with researchers from Southern Cross University.
The research is part of the Reef Restoration and Adaptation Program, funded by the partnership between the Australian Government’s Reef Trust and the Great Barrier Reef Foundation, to help the Reef resist, adapt and recover from the impacts of climate change.
Dr Alroe said they had used the sports field at Kelvin Grove to test the viability of a prototype sprayer system designed to spray a fine mist of seawater over large areas of the reef, shading and cooling the water to prevent bleaching during weather conditions that stress coral.
“The team’s initial results showed that, under the right conditions, a single sprayer could generate a short-lived plume capable of blanketing a sports field and producing a measurable reduction in the incoming sunlight,” Dr Alroe said.
“Our aim is to reduce the sun’s intensity over the reef by generating a low-lying mist directly over the ocean surface during extended periods of still and hot weather, (known as the doldrums) when the coral is most at risk of stress and bleaching.
“We know that these conditions are one of the factors causing reef damage and that clouds and fog effectively reflect a proportion of the sunlight, reducing the impact on the underlying reef.”
Reef Restoration and Adaptation Program executive director Dr Cedric Robillot said climate change was the single greatest threat to the Great Barrier Reef.
“While the world works to address emissions reduction, alongside conventional management and conservation strategies, it is imperative that we research possible solutions to protect existing coral reefs and their biodiversity from the impacts of climate change.”
Professor Ristovski said these experiments were an initial trial to validate the testing method and to obtain preliminary results before a series of trials on the reef.
“The mist machine is mounted on the ship and operated during appropriate weather conditions,” Professor Ristovski said.
“We conducted the first ship trials in December, and further trials have been carried out in February.
“If this method is successful, the sprayer system would then be scaled up to produce larger plumes capable of shading vulnerable reefs.
“This misting idea is intended as a short-term protection for areas of the reef.
“When the water temperature is high, the corals become stressed and vulnerable to intense sunlight and UV rays, leading to bleaching. So, the misting could be needed for several days at a time to shade the surface and reflect the UV until the weather conditions become more hospitable.”
Dr Alroe said the QUT Kelvin Grove stadium’s playing field was chosen for the first tests because it is protected from the wind, mimicking the lack of wind experienced during calm doldrum weather.
“We used a large sprayer with seawater to create a mist and then measured how much incoming sunlight the mist prevented from shining on the field’s surface,” he said.
“We measured changes in the ground-level solar radiation and sampled the plume from an 8-metre mast installed mid-field to understand the microphysics of the mist plume and plume’s dispersal.”
The QUT fogging trial complements the larger scale cloud brightening trial led by Southern Cross University.
Image resources available here.
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