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Great Barrier Reef halved

Listen to this article A study has shown that over the past 25 years, Australia’s Great Barrier Reef has lost more than half of its corals. The main reason for this is that rising sea and ocean temperatures are causing what is known as coral fading, which eventually leads to severe coral weakness and death.

ByTomasz Andrukajtis

Published: October 15, 2020 - 09:00

Updated: July 22, 2023 - 21:19

Listen to this article

A study has shown that over the past 25 years, Australia’s Great Barrier Reef has lost more than half of its corals. The main reason for this is that rising sea and ocean temperatures are causing what is known as coral fading, which eventually leads to severe coral weakness and death.

Scientists have found that on Australia’s Great Barrier Reef, the largest coral reef system in the world, all types of coral have degraded and their populations have declined significantly.

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Arlington Reef bird's eye view — Aerial view of Arlington Reef photo by Luka Peternel CC BY-SA 4.0

The biggest declines in coral populations occurred after the mass fading events in 2016 and 2017. Unfortunately, the aforementioned phenomenon also occurred this year, which will certainly leave a clear mark on the condition of the entire reef.

The research in question was published in the journal Proceedings of the Royal Society B. The authors are Australian marine and ocean scientists at the ARC Centre of Excellence for Coral Reef Studies in Queensland.

Reef Moore Great Barrier Reef — Rafa Moore photo: Holobionics CC BY-SA 4.0

Scientists assessed the status and size of coral colonies across the reef between 1995 and 2017. They found that coral populations had declined by more than 50% and this was true for all coral sizes and species, but particularly for branching and table corals.

These are large structural species that usually provide habitats for fish and other marine organisms.

Faded corals — Corals affected by bleaching photo by Andreas Dietzel

Professor Terry Hughes, co-author of the study, said these types of coral had been most affected by the massive fading, which had damaged nearly two-thirds of the Great Barrier Reef.

Coral fading or bleaching occurs when corals under stress displace the algae – known as zooxanthellae – that give them their colour. Although corals can recover if normal conditions return, this can take decades.

Main photo: Andreas Dietzel

About author

Tomasz Andrukajtis

Editor-in-chief of the DIVERS24 portal and magazine. Responsible for obtaining, translating and developing content. He also supervises all publications. Achived his first diving certification – P1 CMAS, in 2000. Has a degree in journalism and social communication. In the diving industry since 2008.