Bleached coral on the Great Barrier Reef

SYDNEY, Australia — Mass bleaching on the Great Barrier Reef in the past three months has killed as much as half of the coral in the north but left large parts of the southern reaches with only minor damage, scientists in Australia said on Sunday.

The current bleaching is the third to strike the roughly 1,400-mile-long reef in 18 years and the most extreme scientists have recorded.

“In the north, the mortality rates are off the scale,” said Prof. Terry Hughes, the director of the ARC Center of Excellence for Coral Reef Studies, based at James Cook University in Townsville, Queensland. “There, the coral mortality rates are approaching 50 percent, and the impact of the bleaching is still unfolding.”

But from Cairns, in tropical north Queensland, southward down the east coast of the state, about 95 percent of the coral has survived, Professor Hughes said. Mildly bleached coral should regain its color […]