It sounds almost unbelievable, but researchers have discovered a vast reef hiding behind one of Australia’s biggest tourist attractions.
Using laser data from the Royal Australian Navy, scientists from the University of Sydney, James Cook University and Queensland University of Technology, found fields of strange donut-shaped mounds.
The mounds, spotted from data taken by a LiDAR-equipped aircraft, are Halimeda bioherms – geological structures formed by the growth of a green algae made of living calcified segments.
'We've known about these geological structures in the northern Great Barrier Reef since the 1970s and 80s, but never before has the true nature of their shape, size and vast scale been revealed,' said James Cook University’s Doctor Robin Beaman.
“The deeper seafloor behind the familiar coral reefs amazed us.”
North-westerly view of the Bligh Reef area off Cape York. Depths are coloured red (shallow) to blue (deep), over a depth range of about 50 metres. Bathymetry data from Australian Hydrographic Service [Image: James Cook University]
So far, the team have mapped more than 6,000 square kilometres, more than three times the previously estimated size of the reef.
The discovery throws up almost as many questions as it answers.
'For instance, what do the 10-20 metre thick sediments of the bioherms tell us about past climate and environmental change on the Great Barrier Reef over this 10,000-year time-scale?” says Dr Beaman.
'And, what is the finer-scale pattern of modern marine life found within and around the bioherms now that we understand their true shape?'
He said future research would require sediment coring, sub-surface geophysical surveys, and employing autonomous underwater vehicle technologies to unravel the physical, chemical and biological processes of the structures.