Guardian: The world’s largest coral reef system, located just off the east coast of Australia, has lost more than half its coral cover over the past 27 years—and at present rates of decline, it will halve again within a decade, writes Alok Jha for the Guardian. According to a study published in the Proceedings of the National Academy of Sciences, the main causes are tropical cyclones, predation by crown-of-thorns starfish, and coral bleaching brought on by rising ocean temperatures and acidification. Although coral reef systems cover only a small portion of the ocean’s surface, they support a wide diversity of marine species. Finding ways to protect them is important and “entirely achievable,” says David Curnick of the Zoological Society of London. By reducing global carbon dioxide emissions and agricultural runoff, which feeds the predatory starfish, humans could help ensure better water quality and allow the corals the chance to regrow.