Mortality map for the Great Barrier Reef (GBR) after the massive bleaching event in 2016. The map, detailing coral loss on the GBR, shows how mortality varies enormously from north to south. Graphic: ARC Centre of Excellence for Coral Reef Studies

29 November 2016 (AFP) – A mass bleaching event on the Great Barrier Reef this year killed more corals than ever before, scientists said Tuesday, sounding the alarm over the delicate ecosystem.

The 2,300-kilometre (1,400-mile) long reef—the world's biggest—suffered its most severe bleaching in recorded history, due to warming sea temperatures during March and April, with the northern third bearing the brunt.

Follow-up underwater surveys, backing earlier aerial studies, have revealed a 700-kilometre stretch of reefs in the less-accessible north lost two-thirds of shallow-water corals in the past eight to nine months.

"Most of the losses in 2016 have occurred in the northern, most-pristine part of the Great Barrier Reef," said Terry Hughes, head of the Centre of Excellence for Coral Reef Studies at James Cook University.

"This region escaped with minor damage in two earlier bleaching events in 1998 and 2002, but this time around it has been badly affected."

Further south over the vast central and southern regions, including major tourist areas around Cairns and the Whitsunday Islands, there was a much lower toll. [more]

Record coral kill-off on Great Barrier Reef


Dead table corals killed by bleaching on Zenith Reef, on the Northern Great Barrier Reef, November 2016. Photo: Greg Torda / ARC Centre of Excellence for Coral Reef Studies

29 November 2016 (James Cook University) – Scientists have confirmed the largest die-off of corals ever recorded on Australia’s Great Barrier Reef.

The worst affected area, a 700 km swath of reefs in the northern region of the Great Barrier Reef has lost an average of 67% of its shallow-water corals in the past 8-9 months. Further south, over the vast central and southern regions of the Great Barrier Reef, the scientists were relieved to find a much lower death toll.

“Most of the losses in 2016 have occurred in the northern, most-pristine part of the Great Barrier Reef. This region escaped with minor damage in two earlier bleaching events in 1998 and 2002, but this time around it has been badly affected,” says Professor Terry Hughes, Director of the Australian Research Council (ARC) Centre of Excellence for Coral Reef Studies based at James Cook University, who undertook extensive aerial surveys at the height of the bleaching.

“The good news is the southern two-thirds of the Reef has escaped with minor damage. On average, 6% of bleached corals died in the central region in 2016, and only 1% in the south. The corals have now regained their vibrant colour, and these reefs are in good condition,” says Professor Andrew Baird, also from the ARC Centre, who led teams of divers to re-survey the reefs in October and November.

“This is welcome news for our tourism industry,” according to Craig Stephen, who manages one of the Great Barrier Reef’s largest live-aboard tourist operations.

Tourism on the Great Barrier Reef employs 70,000 people, and generates $5 billion in income each year.

“The patchiness of the bleaching means that we can still provide our customers with a world-class coral reef experience by taking them to reefs that are still in top condition.”

Another silver lining was revealed in the northern offshore corner of the Great Barrier Reef Marine Park, where the loss of coral was lower than the other northern reefs.

“We found a large corridor of reefs that escaped the most severe damage along the eastern edge of the continental shelf in the far north of the Great Barrier Reef,” says Professor Hughes.

"We suspect these reefs are partially protected from heat stress by upwelling of cooler water from the Coral Sea."

Scientists expect that the northern region will take at least 10-15 years to regain the lost corals, but they are concerned that a fourth bleaching event could happen sooner and interrupt the slow recovery.

Contact

Prof Terry Hughes
Director, ARC Centre of Excellence for Coral Reef Studies
Phone: +61 (0)400720164, +61 (0)7 4781 4000 (AEST)
Email: Terry.Hughes@jcu.edu.au 

Professor Andrew Baird
ARC Centre of Excellence for Coral Reef Studies
Phone: 0400 289 770
Email: andrew.baird@jcu.edu.au

Dr Greg Torda
ARC Centre of Excellence for Coral Reef Studies
Phone: 0410 289 156 or 07 4781 5241
Email: gergely.torda@jcu.edu.au

Craig Stephen
Mike Ball Dive Expeditions
Phone: +61 (0)407 027 951
Email: cstephen@mikeball.com

Kylie Simmonds
Communications Manager
Phone: 0428 785 895
Email: kylie.simmonds1@jcu.edu.au

Life and death following Great Barrier Reef bleaching

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