Credit: Andreas Dietzel
Original Published Date: 
Thursday, October 22, 2020

Full article issued by the ARC Centre of Excellence for Coral Reef Studies.

An ARC-supported study of the Great Barrier Reef shows populations of its small, medium and large corals have all declined in the past three decades.

Lead author Dr Andy Dietzel, from the ARC Centre of Excellence for Coral Reef Studies (CoralCoE), says while there are numerous studies over centuries on the changes in the structure of populations of humans—or, in the natural world, trees—there still isn’t the equivalent information on the changes in coral populations.

“We measured changes in colony sizes because population studies are important for understanding demography and the corals’ capacity to breed,” Dr Dietzel said.

He and his co-authors assessed coral communities and their colony size along the length of the Great Barrier Reef between 1995 and 2017. Their results show a depletion of coral populations, particularly of branching and table-shaped corals, which provide the structures important for reef inhabitants such as fish.

The authors of the study also say better data on the demographic trends of corals is urgently needed.

“If we want to understand how coral populations are changing and whether or not they can recover between disturbances, we need more detailed demographic data: on recruitment, on reproduction and on colony size structure,” Dr Dietzel said.

Distinguished Professor Terry Hughes, former Director of the CoralCoE, says that the study records steeper deteriorations of coral colonies in the Northern and Central Great Barrier Reef after the mass coral bleaching events in 2016 and 2017. 

“We used to think the Great Barrier Reef is protected by its sheer size—but our results show that even the world’s largest and relatively well-protected reef system is increasingly compromised and in decline,” Professor Hughes said.

Photo credit: 

The Great Barrier Reef has lost half its corals in the past three decades. Credit: Andreas Dietzel.