Marine ecologist Drew Harvell was a University of Washington doctoral student in zoology in 1982 when she went on a research trip off Panama’s western coast with one of the world’s foremost experts in the biology of coral reefs. Then twenty-six and a relatively inexperienced diver, Harvell was nervous about encountering aggressive bull sharks in the low-visibility waters. But when the group submerged, they were shocked to find that the normally colorful coral had turned ghostly white. Surfacing, Harvell and her fellow students asked their teacher what was going on. “He had no idea,” recalls Harvell, now a professor of ecology and evolutionary biology at Cornell, where she has been on the faculty since 1986. “He was one of the world’s leading coral reef biologists, and he had never seen this before. That was a real wake-up call that new things could happen that we didn’t understand.”
The dive was Harvell’s first encounter with what would come to be known as coral bleaching, a phenomenon that would harm reefs from Australia to the Florida Keys and make headlines worldwide. Bleaching occurs when coral become stressed—due to such factors as temperature changes, pollution, and bacterial infection—and expel the symbiotic, algae-like organisms that nourish them and give them their bright hue. It’s just one of the dangers that the world’s oceans have faced over the past several decades—and in the years since Harvell first witnessed it, she has dedicated her career to studying the myriad threats to this fragile, complex ecosystem, with the ultimate aim of finding ways to protect marine biodiversity.