The Great Barrier Reef Has Lost Half Its Corals In 25 Years
A new study has found that the Great Barrier Reef has lost 50% of its coral populations over the past three decades, with climate change noted as being a key driver of reef disturbance.
Researchers from Queensland’s ARC Centre of Excellence for Coral Reef Studies (CoralCoE) assessed coral communities and colony sizes along Australia’s Great Barrier Reef between the years 1995 and 2017.
It was discovered that virtually all small, medium and large corals had depleted during this time period.
Steeper deteriorations were recorded in the Northern and Central Great Barrier Reef following mass coral bleaching events in 2016 and 2017. The southern part was also exposed to record-breaking temperatures back in early 2020.
Study co-author Professor Terry Hughes said:
The decline occurred in both shallow and deeper water, and across virtually all species – but especially in branching and table-shaped corals.
These were the worst affected by record-breaking temperatures that triggered mass bleaching in 2016 and 2017.
The branching and table-shaped corals provide vital structures for reef inhabitants, with coral decline resulting in habitat loss. This in turn reduces the abundance of fish as well as the productivity of coral reef fisheries.
Professor Hughes added:
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.
Dr Andy Dietzel, the study’s lead author, stated that the impact upon survival and breeding is one of the most significant implications of coral size, explaining:
A vibrant coral population has millions of small, baby corals, as well as many large ones – the big mamas who produce most of the larvae.
Our results show the ability of the Great Barrier Reef to recover – its resilience – is compromised compared to the past, because there are fewer babies, and fewer large breeding adults.
The study authors have stressed the urgent need for better data on the demographic trends of corals, with Dr Dietzel remarking:
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.
With climate change increasing the frequency of reef disturbances, for example marine heatwaves, the study authors have emphasised that ‘there is no time to lose’ in the fight to reduce greenhouse gases.
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CreditsARC CENTRE OF EXCELLENCE FOR CORAL REEF STUDIES
ARC CENTRE OF EXCELLENCE FOR CORAL REEF STUDIES