As the spat between the Australian Government and Unesco rumbles on over the UN body’s intention to list the Great Barrier Reef as ‘In Danger’, local scientists have announced the Reef is in a recovery window after a decade of disturbances.
The Australian Institute of Marine Science’s study released on Monday – entitled Long-Term Monitoring Program – Annual Summary Report on Coral Reef Condition for 2020/21 – shows that, with no major pressures from heat stress or cyclones over the past year, widespread recovery is underway.
Dr Paul Hardisty, CEO of the institute, said its 35-year history of monitoring the Reef shows increases in coral cover are expected during periods of similar low disturbance.
“Coral reefs can recover from disturbances if given enough time and the Reef has been given a breather over the last year,” he said.
Reef is getting fewer such opportunities to recover
“Another year like this will continue the Reef’s recovery, but the increasing prominence of climate-related extreme weather events and crown-of-thorns starfish outbreaks is causing more severe and frequent pressures, giving the Reef fewer opportunities like this to recover.”
Since 2009, the Great Barrier Reef has been hit hard with three mass coral-bleaching events, the fourth wave of crown-of-thorns starfish outbreaks, and 17 cyclones that potentially exposed reefs to damaging waves.
Hard coral cover dipped to a record low in all regions at different times during this period.
Monitoring program team leader, Dr Mike Emslie, said 127 reefs were surveyed in 2021, with 81 of those reefs previously surveyed in the last two years. Over this period, 69 of these reefs had increased in hard coral cover across the Northern, Central and Southern regions of the Great Barrier Reef.
Reef is experiencing a period of exponential growth
Surveys showed much of the increase was driven by fast-growing Acropora corals, known as table and branching corals, which are common to many parts of the Great Barrier Reef.
“We found once these dominant corals re-established after disturbances, they hit a period of exponential growth which has led to the increases we see this year,” Dr Emslie explained.
“However, while they are fast to grow, they are often the first to go – they are susceptible to cyclones, coral bleaching and are the favourite food for 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.”
Each region of the Reef has unique path to recovery
Each region of the Reef has been affected by a different set of disturbances over the last decade, and the path to recovery for each region is unique.
Dr Hardisty said the Great Barrier Reef remains under continued pressure from climate change and requires help to survive into the future.
“The Reef has shown its ability to recover after disturbances before, but such resilience has limits,” he said.
“Continued long-term monitoring to understand how the Reef responds to disturbances is critical to its protection, along with a reduction in global emissions and continued good environmental management.”