Fossil records show how the Great Barrier Reef has survived previous ‘death events’

FOSSILISED coral taken from the edge of the Great Barrier Reef has revealed how it survived five previous “death events”.

THE Great Barrier Reef might be more resilient than we thought, surviving five so-called “death events” in the past 30,000 years.

But the current environmental troubles facing the iconic reef could be the sixth, and possibly final death event, researchers warn.

A new study carried out by scientists led by researchers from the University of Sydney used fossilised coral at the edge of the continental shelf to look back at the history of the reef and the environmental pressures it has faced like changes in sea level and temperature.

The team of scientists reconstructed how the reef shifted and evolved during the past 300 centuries in the face of events like the last glacial period.

In the past, the reef has shifted along the sea floor to deal with changes in its environment, moving either seaward or landward depending on whether the level of the ocean was rising or falling, the researchers found.

Based on fossil data from cores drilled into the ocean floor at 16 sites, they determined the Great Barrier Reef was able to migrate between 20cm and 1.5 metres per year — showing an impressive agility.

The findings — published in the journal Nature Geoscience — suggest that the reef may be more resilient than once thought. But despite the good news, it has likely never faced an onslaught quite as severe as today and the rapid speed of ecological change, researchers said.

“I have grave concerns about the ability of the reef in its current form to survive the pace of change caused by the many current stresses and those projected into the near future,” said the study’s lead author, University of Sydney School of Geosciences associate professor Jody Webster.

The reef may be more resilient than once thought — but can it cope this time around? Picture: Tourism QLD

The World Heritage-listed site, which attracts millions of tourists every year, is reeling from successive bouts of coral bleaching due to warming sea temperatures linked to climate change.

Dr Webster and an international team wanted to view the reef’s current plight within a long-term context. Over 10 years, they studied how it had responded to changes caused by continental ice sheets expanding and waning over 30 millennia.

Their research covers a period from before the “Last Glacial Maximum” or LGM — the peak freeze about 21,000 years ago during the last Ice Age. The average sea level at the time was some 120m lower than today.

As sea levels dropped leading up to the LGM, there were two massive “death events” about 30,000 and 22,000 years ago, the team found. These were caused by the reef being exposed to air. What remained of it inched seaward to rebound later.

As ice sheets melted after the LGM, two die-offs — 17,000 and 13,000 years ago — were due to sea level rise, the team found. In these cases, the reef moved itself landward.

The fifth death event took place about 10,000 years ago, apparently due to a massive sediment dump amid a higher sea level.

Speaking to AFP, Dr Webster said the Great Barrier Reef “will probably die again in the next few thousand years anyway if it follows its past geological pattern” as Earth is believed to be due for another ice age.

“But whether human-induced climate change will hasten that death remains to be seen,” he said.

Fish swim near a staghorn coral that has died from the effects of warm ocean temperatures and coral bleaching on Hastings Reef off Cairns, part of the Great Barrier Reef Marine Park. Picture: Brendan Radke

GREENS PUSH FOR GREAT BARRIER REEF INQUIRY

For years, conservationists have been calling on the government to allocate greater funding for efforts to protect the Great Barrier Reef.

A new controversy has emerged with the Greens demanding to know why $444 million in taxpayers’ money was handed to a small charity without using a competitive tender process.

Tomorrow the party will call for an inquiry to look at the Reef 2050 Plan and whether the Great Barrier Reef Foundation can deliver it.

“So many questions remain unanswered into how this small foundation, governed by people from big business and the fossil fuel sector, has been granted hundreds of millions in public funding,” Greens senator Peter Whish-Wilson said. “And why the government bypassed the specially designed public bodies that are already doing this work.”

Mr Whish-Wilson said the government overlooked the Australian Institute of Marine Science, a body set up by former Liberal prime minister John Gorton to study the reef.

It also ignored the Great Barrier Reef Trust, a body set up by the Coalition in 2013 to devolve funds to various groups.

“We need a Senate inquiry to get to the bottom of this debacle. Every planning and governance process that has been put in place to get the best benefit from public spending on the reef has been thrown out the window,” he said.

A Senate hearing last week was told The Great Barrier Reef Foundation was chosen to get $444 million of taxpayer money to protect the reef without being asked if they wanted it or how they’d spend it.

— With AFP, AAP