'Dead corals don’t make babies' - Coral baby numbers crash on the Great Barrier Reef

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After the mass bleaching events on the Great Barrier Reef in 2016 and 2017, the number of new corals settling on the Great Barrier Reef dropped by around 90 per cent compared to historical levels, according to Australian research, drawing into question the ability of the reef to recover. The study also found that the mix of baby corals has shifted which will also impact reef recovery. Given the projected increase in the frequency of extreme climate events, the researchers say the extent to which the Great Barrier Reef will be able to recover from this type of collapse remains uncertain.

Journal/conference: Nature

Organisation/s: ARC Centre of Excellence for Coral Reef Studies, James Cook University, Macquarie University, Australian Institute of Marine Science (AIMS)

Funder: Australian Research Council’s Centre of Excellence Program (CE140100020)

Media Release

From: Springer Nature

How coral recovery is impaired on the Great Barrier Reef

After the mass bleaching events in 2016 and 2017 on the Great Barrier Reef, recruitment of new coral larvae fell by 89% according to a study published online in Nature this week. Given the projected increase in the occurrence of extreme climate events over the next two decades, the extent to which the Great Barrier Reef will be able to recover is unclear.

The Great Barrier Reef experienced mass bleaching events four times in the past 20 years and, under a business-as-usual scenario for greenhouse gas emissions, projections suggest that it will bleach twice a decade from 2035 and annually after 2044.

To investigate the capacity of the Great Barrier Reef to recover after extreme climate events, Terry Hughes and colleagues examined the relationships between the adult stock and larval recruitment of corals before and after the mass bleaching events in 2016 and 2017. The authors found that the loss of adult coral was associated with a collapse in larval recruitment and there was a shift in the composition of the coral species that were recruited. Brooding species of coral release fertilized larvae that typically settle within a day, whereas spawners release eggs and sperm that are externally fertilized and larval settlement takes place four to seven days later. In the depleted recruitment pools, they observed that locally sourced larval recruits of brooders became the dominant population rather than the more widely dispersed and diverse larvae of spawners.

The authors conclude that the shift in larval recruitment will influence the composition of recovering coral assemblages and could affect their ability to cope with bleaching events in the future.

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  • Reef Recovery

    Australian Academy of Science Fellow Prof Terry Hughes on how coral baby numbers have crashed on the Great Barrier Reef.

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    Attribution: Australian Academy of Science

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    Last Modified: 04 Apr 2019 4:00am

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