Confirmed: 2016 GBR Bleaching Biggest Coral Die-Off On Record; Mortality Varied By Region
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."
EDIT
Scientists estimate the northern region, which teems with marine life, will take at least 10-15 years to regain lost corals, but are concerned that a fourth major bleaching event may occur before that, hampering the recovery. The reef studies centre warned earlier this year that if greenhouse gas levels keep rising, similar events would be the new normal, occurring every two years by the mid-2030s. Given reefs need so long to recover from severe bleaching, it said "we are likely to lose large parts of the Great Barrier Reef in just a couple of decades".
EDIT
http://phys.org/news/2016-11-coral-kill-off-great-barrier-reef.html