Curtin University researchers are creating snapshots of past Australian environments using the minute traces left behind by plants, animals and microorganisms. Dr Svenja Tulipani and Professor Kliti Grice from the WA-Organic and Isotope Geochemistry Centre looked for clues in sediments at Coorong National Park, South Australia, to find out how this system of coastal lagoons has changed since European settlement.
The Coorong Wetland is an ecologically significant area, but human water management practices and severe drought have led to increased salinity and less biodiversity, Tulipani explains. By examining microscopic molecular fossils, known as biomarkers, and their stable carbon and hydrogen isotopes, the researchers have identified the types of organisms that previously lived in the area, uncovering evidence for changes in water level and salinity due to changes in carbon and hydrogeological cycles.
“We found significant changes that started in the 1950s, at the same time that water management was intensified,” Tulipani says. “It affects the whole food web, including the birdlife and ecology,” Grice adds.
“We found significant changes that started in the 1950s, which was the same time that the water management was intensified.”
The project used Curtin’s world-class instruments for gas chromatography-mass spectrometry, as well as a new instrument that is capable of even better analysis.
“It allows for a new technique that reduces sample preparation time as the organic compounds can be analysed in more complex mixtures, such as whole oils or extracts of sediments and modern organisms,” Tulipani explains. “We can also identify more compounds this way.”
Tulipani has been able to use samples taken from the remote Kimberley region to examine an extinction event around 380 million years ago. Grice says the techniques are particularly relevant to the evolution of primitive vascular plants during this time period.
“In some locations of the Pilbara region, you can look at very early life from more than 2.5 billion years ago. You can go back practically to the beginning of life.”
– Michelle Wheeler