Australian researchers have studied and documented the effect of the "sundried tide", a force of nature that can silently wipe out coral reefs.

Their analyses have revealed for the first time that these are highly predictable events that can seriously impact the state of coral reefs at a time when they are preparing for the stresses of summer.

In a paper published in scientific journal Marine Biology, Dr Ken Anthony and Dr Ailsa Kerswell, of the ARC Centre of Excellence for Coral Reef Studies (CoECRS) at The University of Queensland (UQ) and James Cook University (JCU) have revealed that extreme low tides on clear sunny days can lead to widespread damage of coastal coral colonies.

"Really low tides, where the local sea level gets to its extreme low for the year, can occur at different times of the day," UQ's Dr Anthony said.

"In years where this occurs during the middle of the day when the sunlight is at its most intense and the reefs are almost fully exposed, there is a real risk of severe coral stress and death in the shallow reef zone."

Just like cyclones and other natural disasters, these severe sun-dry tides' rarely occurred since they relied on the alignment of numerous natural extremes, he said.

However, when these factors all aligned, by a combination of sun, moon and chance weather, an extreme event occurred which could leave coral colonies bleached and devastated.

One such event occurred in September 2005 while Dr Anthony and Dr Kerswell were taking JCU students on a field trip to Orpheus Island off the Queensland coast.

While doing some field work we noticed that all the corals in the area were about to die, so we took the opportunity to record the event, Dr Kerswell said.

Their observations led Dr Anthony and Dr Kerswell to investigate the mysterious coral deaths on Orpheus Island a study which would reveal that what they had witnessed was a rare event,
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Contact: Dr. Ken Anthony
61-733-659-154
ARC Centre of Excellence in Coral Reef Studies
3-Jul-2007