For corals, it is survival of the fattest.

• Position: Global Warming

The future health of the world's coral reefs and the animals that depend on them relies in part on the ability of one tiny symbiotic sea creature to get fat--and to be flexible about the type of algae It cooperates with. Scientists at Ohio State University, Columbus, have discovered that tiny reef-forming animals that live symbiotically with algae are better able to recover from yearly bouts of heat stress--called "bleaching"--when they keep large energy reserves (mostly as fat) socked away in their cells.

"We found that some coral are able to acclimatize to annual bleaching, while others actually become more susceptible to it over time," says Andrea Grottoli, professor in the School of Earth Sciences. "We concluded that annual coral bleaching could cause a decline in coral diversity, and an overall decline of coral reefs worldwide."

Biology indicates that some coral species almost certainly will decline with global warming, while others that exhibit large fat storage and flexibility in the types of algae they partner with will stand a better chance of enduring repeated rounds of stress as oceans get hotter. It also suggests that the most adaptable species would make good targets for conservation efforts because they are most likely to survive.

"If we conserve reefs that contain coral species with these survival traits, then we're hedging...