Historic signs of Great Barrier Reef regrowth

The Great Barrier Reef has undergone a dramatic change for the better without disturbances from heatwaves and tropical cyclones.

AIMS scientists have been assessing the health of the Great Barrier Reef for more than 35 years. Picture: Australian Institute of Marine Science

The latest report into the health of the Great Barrier Reef has found historic signs of regrowth, thanks to a year without disturbances from heatwaves and tropical cyclones.

“We’ve never seen anything of this magnitude,” lead researcher Dr Mike Emslie from the Australian Institute of Marine Science (AIMS) said.

A total of 127 reefs were surveyed, with 69 showing increases in hard coral cover.

The signs of regrowth were apparent in the Northern, Central and Southern parts of the 2300km long reef. Coral cover was at 27 per cent in the north, 26 per cent in the centre and 39 per cent in the south.

The lack of heatwaves and tropical cyclones meant the Reef had had “essentially a breather, a bit of a reprieve,” Dr Emslie said.

In an average year the Great Barrier Reef could be hit by three or four cyclones but in 2021 no cyclones came onto the reef itself, Dr Emslie said.

The report comes just days before UNESCO’s World Heritage Committee meets to determine whether the Reef’s status should be changed to ‘in danger’.

In June the Committee signalled it would likely change that status.

It’s been a bumper year of regrowth on the Great Barrier Reef.

AIMS Chief Executive Officer Dr Paul Hardisty deflected questions about what this report meant for the World Heritage Committee determination, saying: “As a national science agency, we don’t have an opinion on that; that’s for others. We do not comment on policy.”

Environment Minister Sussan Ley said the report “underlines our view that the World Heritage Committee proposed listing had not been based on the latest information.”

“The report recognises the very real challenges for the Reef in the face of changing climates and extreme weather events, but it also underlines the capacity of the Reef to recover,” she said.

“The clear message from this year’s survey is that coral recovery can take place, and is taking place, in the right conditions.”

AIMS CEO Dr Paul Hardisty.

Dr Mike Emslie in the field on the Great Barrier Reef. Picture: Supplied

This year’s report comes after the 2020 study, which found “encouraging” signs of coral growth in the central and southern parts of the reef, and a stabilisation of coverage in the northern region. Of 86 monitored reefs, two thirds were showing signs of modest growth in 2020.

“There is some encouraging news in this report and another good year would help continue recovery, but we also have to accept the increasing probability of extreme weather events and crown of thorns star fish outbreaks which can reverse recovery,” Dr Hardisty said.

Dr Emslie warned much of the coral growth they had seen in 2021 came from Acropora corals, which are “fast to grow ... (but) often the first to go” as they were more susceptible to cyclones, coral bleaching and the crown-of-thorns starfish.

“Because of these vulnerabilities and likelihood of more climate-related severe weather events, future disturbances may result in rapid decline on these reefs,” Dr Emslie said.

The prognosis for the reef was of “escalating pressure” because of climate change, he said.

“The Great Barrier Reef is under continual pressure. We will see disturbances in the years ahead,” Dr Emslie said.