Coral key to climate change

25 March 2008

A researcher from Queensland University of Technology has advanced the use of coral to measure the rate of climate change.

Studying coral at Heron Island, at the southern end of the Great Barrier Reef, QUT natural resource sciences PhD researcher Luke Nothdurft has greatly improved the accuracy of coral analysis, keeping it up-to-date with recent advances in technology.

"Analysis of coral can tell us about the changes in water temperature over time and the rate of global warming," Mr Nothdurft said.

"Corals are great continuous recorders of past sea conditions. A single colony can grow for several hundred years.

"Their skeletons contain trace elements incorporated from seawater as they grow, and these trace element concentrations change as water temperatures fluctuate."

Mr Nothdurft said recent technology used to analyse coral chemistry was so advanced that new sampling strategies had to be developed to ensure accuracy.

"Existing sampling strategies were impossible to use with this new technology because they could lead to great inaccuracies," he said.

"In the past, we could only see the annual density bands of coral, which are superficially similar to tree rings, but now, powerful microscopes have made it possible to see seasonal, weekly and even daily variations in coral growth."

Mr Nothdurft studied the skeletal structure of different coral species and found that coral skeleton is much more complicated than previously thought.

"Coral skeletons have different microstructures, which grow at different times. You need to look at how the structure is built before analysing the sample, otherwise you may mistake new growth for old," he said.

"The coral animal is only a thin living polyp on top of the skeleton. As it grows it leaves the skeleton base beneath it.

"The skeletons are very complex and there are many variations between species."

Mr Nothdurft also discovered that minerals deposited from seawater and by organisms living within abandoned parts of the coral skeleton could also mislead scientists.

"These secondary mineral precipitates in the cavities within coral skeletons potentially contaminate the sample with chemical properties that do not reflect the local seawater environment," he said.

Mr Nothdurft undertook the research with an Australian Research Council postgraduate award and a QUT-funded grant. He was supervised by QUT marine carbonate geologist Dr Greg Webb.

Media inquiries: Carmen Myler, QUT media officer - 07 3138 4494.
**high-res images of Mr Nothdurft are available from Erika Fish:

Researcher Luke Nothdurft is improving the analysis of coral, which will help us measure the rate of global warming.