RainBow Reefs

Fiji's reefs can take a punch and come back swinging Expert at being both whomped and resilient, these reefs are prime ground for scientists struggling to understand the catastrophic decline of Earth's coral habitats. Though cyclones, disease, predators, and volcanic eruptions all harm reefs, corals tend to regenerate after such natural blows. But the carbon-dioxide-rich atmosphere humanity is brewing, and the resulting rise in sea temperatures, may cripple coral's ability to recover.When water heats up, corals expel the symbiotic algae that provide nutrients and color, leaving the corals "bleached." Some scientists theorize that bleaching evolved to help corals adjust to shifting temperature by swap-ping existing algae for others more heat-hardy. But as global temperatures rise, corals are reaching their upper limits of heat tolerance. In Fiji corals can survive in waters up to about 86°F. Beyond that, it's like asking corals to shift into a gear they just don't have. Fiji's reefs took a major hot-water hammering in 2000 and 2002, leading to widespread bleaching. As a marine biologist long interested in coral reefs, I joined a recent expedition to Fiji to see how its reefs were faring after the heat waves. We found vast differences from place to place. Stripped of algae, some corals had starved and died, leaving denuded limestone hulks. But in some spots where staghorn and other hard corals had bleached white, new life blossomed. We saw gardens of baby corals sprout ting over fields of bare rock, multicolored sea life mobbing newly lush pastures, and some reefs that had entirely escaped bleaching. Big fish swam all around us—sharks, groupers, mantas, all evidence of a sys-tem with a hard-beating heart Fiji is like the patient who did not die of AIDS, and global reef health may depend on learning why. Support is growing to create protected areas around some of Fiji's reefs, where scientists can hunt for answers. Protection will help ensure that bleaching events won't be compounded by polluted runoff, over fishing, or eager tourists. But in the end, human ability to turn down the heat may ultimately determine either death or renewal.