Lonely Planet Writer

Scientists have discovered a massive reef hidden behind the Great Barrier Reef

It turns out there’s more to one of Australia’s top tourist destinations than meets the eye – as scientists announce they have discovered a vast reef hidden behind the famous Great Barrier Reef.

Aerial view of Great Barrier Reef, Queensland, Australia.
Aerial view of Great Barrier Reef, Queensland, Australia. Image by tororo reaction

Scientists from James Cook University, the University of Sydney and Queensland University of Technology used laser data from the Royal Australian Navy to discover the geological structures located near the reef. The high-resolution data showed the seafloor, revealing “unusual donut-shaped circular mounds” about 200 to 300 metres across and up to 10 metres deep.

“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 Dr Robin Beaman in a statement. “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.
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. Image by Australian Hydrographic Service

The rings are actually ‘Halimeda bioherms’, which are reef-like structures caused by the growth of an algae – called Halimeda – composed of living calcified segments, which bond together into bioherms. The new discovery also covered about 6000 square kilometres, forming “a significant inter-reef habitat which covers an area greater than the adjacent coral reefs.”

The Great Barrier Reef is a top tourist attraction in Australia, with the consumer advice publisher U.S. News & World Report naming it the best spot for a vacation in 2016-17. But concerns are mounting over the health of the reef due to climate change, water temperatures and coral bleaching.

Clownfish, Great Barrier Reef.
Clownfish, Great Barrier Reef. Image by Paul Arps / CC BY 2.0

According to the statement from researchers, associate professor Jody Webster from the University of Sydney said the discovery has made questions over the structures’ vulnerability to climate change eve more important.

“As a calcifying organism, Halimeda may be susceptible to ocean acidification and warming. Have the Halimeda bioherms been impacted, and if so to what extent?”