Mass bleaching has killed more than a third of the coral in the northern and central parts of Australia's Great Barrier Reef, though corals to the south have escaped with little damage, scientists say. Researchers who conducted months of aerial and underwater surveys of the 1,400-mile reef off Australia's east coast found that around 35% of the coral in the northern and central sections of the reef are dead or dying, says Terry Hughes, chief of coral reef studies at James Cook University in Queensland state. And some parts of the reef have lost more than half of the coral to bleaching, which happens when hot water puts stress on coral, causing it to turn white and become vulnerable to disease, the AP reports..
The extent of the damage has serious implications, Hughes says. Older corals take longer to bounce back from bleaching, and likely won't have a chance to recover before the next bleaching event occurs, he says. And dying coral affects much more than the coral itself—it affects other creatures that rely on coral for food and shelter. "Is it surprising? Not anymore. Is it significant? Absolutely," says Mark Eakin, the NOAA's coral reef watch coordinator. "We're talking about losing 35% of the population of coral in some of these reefs—that's huge." The damage is part of a massive bleaching event that has been impacting reefs around the world for the past two years. Experts say the bleaching has been triggered by global warming and El Nino.