The discovery was made off Lord Howe Island, which is located 600 kilometres east of Australia, by a research team led by University of Wollongong and Geoscience Australia scientists. Lord Howe hosts the world’s southernmost modern reef, but no ancient reefs have previously been discovered this far south.

The scientists estimate that the reef is about 9,000 years old, and that it died around 7,000 years ago when sea levels rose. However, it also contains younger corals of 2,000 years old, suggesting that it may provide suitable habitat for new coral growth if sea temperatures rise.

Coral growth at these latitudes is currently limited by water temperature, but if oceans warm as predicted, these corals could flourish.

Ocean warming is known to be damaging to coral, causing bleaching of reefs in the tropics. However, the authors suggest that rising temperatures at higher latitudes may also stimulate new growth. ‘This relict reef, with localised re-establishment of corals in the past three millennia, could become a substrate for reef expansion in response to warmer temperatures, anticipated later this century and beyond, if corals are able to recolonise its surface,’ the authors said.

If similar relict reefs are found at higher latitudes in the Northern Hemisphere, it’s possible that they, too, may be able to support new growth. 

KARA MOSES
November 2010