“This sensor network has been operational and collecting data since June 2018.”
So far, scientists have more than 150 million data points and preliminary findings show cooler water is available at the site during summer.
Dr Long said although there was no coral bleaching event during the most recent summer, there was about a week of very calm and hot weather in November.
At that time, natural wind-driven mixing of the water column failed, leaving warm water trapped on the top layer, becoming “hotter and hotter and hotter each day.”
“At 14 metres depth, the water temperature was two degrees cooler than at the surface and at 30 metres depth, the water was three degrees cooler than the surface,” Dr Long said.
“This might not sound like much, but to a shallow coral right on the edge of its thermal tolerance under those heatwave conditions, just a degree or two could make a big difference to its survival.”
Dr Long said the next question to be answered was whether restoring normal water column mixing during hot, calm heatwave conditions could improve outcomes for shallow corals.
Researchers hope to use the existing data to inform the design of a “mixing intervention”, but it is still subject to the steering group’s approval and the Great Barrier Marine Park Authority.
Dr Long said the Reef Havens Research Project would not save the Great Barrier Reef from climate change and global action to reduce emissions was essential.
“However, so are local actions that facilitate survival and adaptation, rather than death, while global-scale solutions are enacted,” she said.
“What we are trying to do is start the process of developing some science-based tools and methods that could help some corals survive and adapt, rather than just die during these hot, calm heatwave conditions, which are going to become more frequent.”
Dr Long said during heatwaves on land, people could take action, such as spraying water on flying fox roosts to help the animals cool down.
“By contrast, on the Great Barrier Reef during a coral bleaching event, all managers can do is wring their hands and watch things die,” she said.
“If we find that restoring water column mixing can reduce coral stress and improve outcomes during a coral bleaching event, then definitely, it’s an approach that should probably be considered for more sites.
“If/when we do deploy a mixing intervention we will be able to measure changes in coral stress as a result of restoring mixing, without having to wait for a serious bleaching event to occur.”
Felicity Caldwell is state political reporter at the Brisbane Times