After a series of devastating and widespread disturbances over the last decade, the Great Barrier Reef is currently in a recovery window with coral cover rising in all three regions; the Northern, Central, and Southern reefs.
The Australian Institute of Marine Science’s (AIMS) Long-Term Monitoring Program posted their Annual Summary Report on Coral Reef Condition for 2020/21 which showed widespread recovery of the Reef.
AIMS CEO Dr. Paul Hardisty said AIMS’ 35-year history of monitoring the Reef observed that increases in coral cover are expected during periods of 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.
However, Hardisty noted that the Reef’s recovery is still threatened by the increasing prominence of climate-related extreme weather events and crown-of-thorns starfish outbreaks.
WHEN THE PROBLEM STARTED
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 hit a record low in all regions at different times during this period.
AIMS monitoring program team leader Dr. Mike Emslie reported that of the 81 reefs previously surveyed in the last two years, 69 had increased in hard coral cover across the Reef.
The increase is largely attributed to the fast-growing Acropora corals. They found that the branching corals hit a period of exponential growth; re-establishing themselves after disturbances.
“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,” Emslie said.
Emslie fears that these vulnerabilities may cause future disturbances resulting in rapid decline on these reefs.
Each region of the Reef has been affected by different sets of disturbances over the last decade and they require unique paths to recovery.
The Southern reefs experienced the highest increase in region-wide hard coral cover at an estimated 39%; which AIMS classifies as ‘high’. This is a significant increase compared to the 12% in 2011.
While conditions vary in the Northern reefs, hard coral cover has continued to increase to 27% this year. This is classified to be ‘moderate’ increase but is still a significant increase from the lowest level of 13% in 2017.
The Central region now has an average hard coral cover of 26%. Though also classified as ‘moderate’, this is also a significant increase compared to the 11% in 2012.
“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.” Hardisty said.
ABOUT THE GREAT BARRIER REEF
The Great Barrier Reef is the world’s largest coral reef system with 400 types of coral, 1,500 species of fish, and 4,000 types of mollusks.
It also holds great scientific interest as the habitat of species such as the dugong (‘sea cow’) and the large green turtle, which are threatened with extinction.
