Record coral kill-off on the Great Barrier Reef

SYDNEY: A mass bleaching event on the Great Barrier Reef this year killed more corals than ever before, scientists said yesterday, sounding the alarm over the delicate ecosystem.

The 2,300-kilometre (1,400mile) 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, mostpristine 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 areas around Cairns and the Whitsunday Islands, there was a much lower toll. Bleaching occurs when abnormal environmental conditions, such as warmer sea temperatures, cause corals to expel tiny photosynthetic algae, draining them of their colour. — AFP

Researcher Grace Frank completing bleaching surveys along a transect line on an area known as One Tree Reef, in the Capricorn Group of Islands, on the Great Barrier Reef in Australia. — Reuters photo