Survey reveals secrets of life on the edge


A diverse seabed community of corals
and algae growing on the fossil reef
adjacent to Balls Pyramid, photographed
during a recent marine survey on the RV
Southern Surveyor. The view is of
approximately one square metre
of the seabed.

A recent marine survey has discovered evidence that a large coral reef once flourished around Balls Pyramid, a spectacular remnant of an ancient volcano in waters off Lord Howe Island, at what is now the very southern limit of reef-forming coral.

Balls Pyramid is located just south of Lord Howe Island and about 600 kilometres east of Port Macquarie on the Australian east coast. The survey was conducted to help inform the management of the Lord Howe Island Marine Park and the Lord Howe Commonwealth Marine Reserve.

Geoscience Australia marine geologist, Dr Brendan Brooke, said that the coral reef likely formed around 8000 years ago when the sea level was about 30 metres lower than today. The Balls Pyramid reef is similar to a drowned reef that surrounds nearby Lord Howe Island, which is many times larger than the island's modern fringing reef, the most southern coral reef in the Pacific Ocean.

"Underwater core samples we gathered from around Balls Pyramid contained reef limestone which will help us understand how coral reefs responded to changes in ocean climate 8000 years ago," Dr Brooke said.

"The new information will also help to develop a better understanding of the Lord Howe Island marginal reef we see today," he said.

"Video footage collected over the fossilised reef during the survey provides key information about seabed habitats, including extensive, previously unknown, areas of coral and sponge communities that now grow on the ancient reef," Dr Brooke added.

The survey, using Australia's Marine National Facility research vessel, Southern Surveyor, was undertaken by researchers from the University of Wollongong and the NSW Department of Primary Industries as well as Geoscience Australia. During the survey the seafloor was mapped using a multibeam echosounder and an underwater camera system. The project is part of a collaboration facilitated under the National Environmental Research Program's Marine Biodiversity Hub.

The importance of marine research to Australia's economy and to furthering our knowledge of Australia's vast marine jurisdiction was recognised with the recent release of the Australian Government's Marine Nation 2025 report. Marine Nation 2025 identifies the national challenges facing Australia and its marine estate, and how marine science can contribute to finding solutions.