Temporary sunshades for small parts of the reef could help coral fight the effects of a "sun-dried tide", a rare natural event that can devastate coral communities, says Dr Ken Anthony of the Australian Research Council Centre for Excellence for Coral Reef Studies.
Research by Anthony and colleague Dr Ailsa Kerswell shows extreme low tides on a clear, sunny day with little wind can weaken and kill coral reefs as they prepare for the stressful times of spawning and summer.
But Anthony says their research shows they can predict a sun-dried tide and forecasts of its arrival could become an important tool in managing the reef.
In a paper published recently in the journal Marine Biology, the researchers describe what happened during a September 2005 event at Orpheus Island, off the North Queensland coast.
During a sun-dried tide, 40-75% of the major coral taxa were either bleached or partially destroyed.
But in areas where the coral was not protected from the wind and was periodically washed by waves, less than 1% of coral was bleached.
Anthony says the discovery was made during a field trip with a group of James Cook University students.
"It was a total shock ... there were 13,000 corals and about half of those were about to die," he says. "We thought it was a mass disease event. We didn't think about the tides being the culprit until we had exhausted all other options."
Anthony and his team tracked hourly tidal records between 1997 and 2005 and combined this with hourly data on wind and sun patterns to estimate the likelihood of coral being exposed.
Their analysis shows the 2005 event was the most severe of its kind in the past eight years.
Anthony is forecasting another sun-dried tide in September or October this year and says the severity will depend on factors such as cloud cover and winds.
But because the deadly tides are highly predictable, the forecast can be used to manage human impact on the reef, he says.
"We can't do much about the impact of other stresses such as climate change at a local level," he says.
"But what we can say is that this year a reef is really vulnerable so let's make sure it is saved from other stresses such as overfishing."
At the time of a sun-dried tide tour operators could also be encouraged to provide shade on small areas of reef.
"It's not such a silly idea," Anthony says. "There is no real way you can prevent corals coming out of the water and the Sun shining. But tour operators could provide shade; if you can shade out light you can save the coral."
Sun-dried tides also affect the reef's ability to regenerate as the tides hit just as corals are preparing for the spawning season.
"Corals that do experience a sun-dried tide won't be able to build up the energy needed for spawning," he says.