Great Barrier Reef’s great-grandmother is unearthed

  • 19 August 2010
  • Magazine issue

 Age before beauty, when it comes to coral? (Image: Naoi/ Flickr/Getty)
Age before beauty, when it comes to coral? (Image: Naoi/ Flickr/Getty)

JUST 600 meters away from the Great Barrier Reef, the jewel in Australia’s crown, a less spectacular but more ancient reef has been discovered.

The first hint of its existence came in 2007, when seismic and sonar measurements revealed odd ridges and lagoons on the seabed. Confirmation arrived in February this year, when an international team extracted 34 sediment cores from three sites on the seabed, revealing a fossilized coral reef that reaches 110 meters into the sea floor. Preliminary dating of the core indicates that the coral is up to 169,000 years old.

“This is the great-grandmother of the Great Barrier Reef,” says John Pandolfi of the University of Queensland, who was not on the mission. It is “a very important discovery”, he says, and should provide new insights into the genesis of the reef.

The prevailing wisdom has been that the Great Barrier Reef sits atop an older, dead reef, but 110 meters beneath the live reef, the team hit rock. Corals need light to live, and Pandolfi now thinks that when rising sea levels at the end of the last ice age threatened to put the lights out on the ancient reef, some larvae traveled to shallower waters and seeded the modern one.

The findings were presented by Jody Webster of the University of Sydney at the Integrated Ocean Drilling Program conference in Bremen, Germany, in July.

Issue 2774 of New Scientist magazine

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