In this Friday Nov. 25, 2016, photo Australian senator Pauline Hanson listens to marine scientist Alison Jones, left, as she displays a piece of coral on the Great Barrier Reef off Great Keppel Island, Queensland, Australia. (Dan Peled, AAP Image via AP)
Canberra, Australia: Warming oceans this year have caused the largest die-off of corals ever recorded on Australia's Great Barrier Reef, scientists said Tuesday.
The worst-affected area is a 700-kilometre (400-mile) swath in the north of the World Heritage-listed 2,300-kilometre (1,400-mile) chain of reefs off Australia's northeast coast, said the Australian Research Council Centre of Excellence for Coral Reef Studies.
The centre, based at James Cook University in Queensland state, found during dive surveys in October and November that the swath north of Port Douglas had lost an average of 67 per cent of its shallow-water corals in the past nine months.
Farther south, over the vast central and southern regions that cover most of the reef, scientists found a much lower death toll.
The central region lost 6 per cent of bleached coral and the southern region only 1 per cent.