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) 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, the extent of which had never previously been recorded on the Great Barrier Reef .
“At first we thought it was a major outbreak of disease," Dr Kerswell said.
"We collected samples and took hundreds of photos and sent a series off to colleagues to be analysed. The response was that it was not a disease, but something else.
“[So] we looked back through hourly records of tidal patterns over the previous eight years and combined it with data on solar records and models."
Dr Anthony said the researchers aligned what the tide would do with the sun and weather patterns and ran an analysis of the risk of corals being out of the water and exposed to the sun.
During September 2005 Dr Anthony, Dr Kerswell and the students were present the week following a rare extremely low tide during which the sun had been shining from a clear sky.
These "natural disasters" occur silently but can devastate the tidal zone. From past records Dr Anthony estimated that the September 2005 event was the worst in the eight-year record.
However, the "sundried tides" could also be anticipated.
"These events are highly predictable," Dr Anthony said.
"We can go into the weather reports, align them with tidal charts and predict the times of greatest risk.
"The high-risk time of year is July–October, when corals are building up resources for spawning and preparing for summer stressors such as thermal bleaching."
Since studying the cause and impacts of these major events, Dr Anthony hopes that their predictable nature will lead to improved warning systems and better models for predicting stress and mortality in corals.
Although predictable and natural, "sundried tides" were unavoidable and compounded the stresses already felt by corals due to climate change and human impacts, he said.
"However, if we better understand the timing and severity of natural stressors on reefs, we will be able to better predict the risks of human-induced stressors, and hopefully better manage for healthy reefs," he said.Paper:
Link to full text or pdfMore information:
Dr. Ken Anthony | EurekAlert!
Bioinvasion on the rise
15.02.2017 | Universität Konstanz
Litter Levels in the Depths of the Arctic are On the Rise
10.02.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".
Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
24.02.2017 | Life Sciences
24.02.2017 | Life Sciences
24.02.2017 | Trade Fair News