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The tiny, slimy savior of global coral reefs?

Heat-tolerant algae could help the world's reefs adapt to climate change, researcher says.

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Half a billion people, probably more, rely directly on coral reef ecosystems for food. And now, at the beginning of what many call the “genomic era,” scientists are seeing the diversity of life on reefs – and biodiversity in general – in a new, utilitarian light. Each unique life form (genome) represents a novel set of solutions to life’s challenges. Now that scientists can isolate and utilize this information directly, ensuring its continued existence takes on added urgency.

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'Mining' biodiversity to make money
Gregor Hodgson, executive director of the Reef Check Foundation in Pacific Palisades, Calif., points to new leukemia and pain drugs derived, respectively, from a reef-dwelling sponge and the venom of a reef-dwelling snail. (The revolution in molecular biology itself, driven by rapid ­gene-sequencing technology, is possible only because of enzymes found in microbes living in a Yellowstone hot springs.)

“This genetic resource is unsurpassed,” says Dr. Hodgson.

But by all accounts, reefs are in crisis. The Global Coral Reef Monitoring Network’s “Status of Coral Reefs of the World: 2008” estimates that, since 1950, the world has lost 19 percent of its reefs. Another 15 percent may disappear within the next 10 to 20 years.

Some Caribbean islands have lost half their coral cover. In 2006, the US National Marine Fisheries Service listed two Caribbean corals – elkhorn and staghorn – as “threatened” under the Endangered Species Act, the first coral species to earn the designation.

“Corals are really in a world of hurt,” says C. Mark Eakin, coordinator of the National Oceanic and Atmospheric Administration’s (NOAA) Coral Reef Watch in Silver Spring, Md. “We need to do everything we can to help.”

Coral reefs colonize 'marine deserts'

Reef-building corals inhabit the equivalent of marine deserts: ­nutrient-poor waters with lots of sun. But increased nutrients from fertilizer and sewage runoff, among other sources, tip the environment toward favoring algae rather than coral. Chronic overfishing – the removal of grazers that might otherwise keep algal growth in check – also contributes to what oceanographer Jeremy Jackson has dubbed “the rise of slime.” In places like Jamaica – home to some of the Caribbean’s most degraded reefs – seaweed now dominates former coral reefs.

Coral health also depends on healthy intact ecosystems. A disease that decimated Caribbean sea urchins (an algae grazer) in the 1980s has been implicated in a regional reef decline, for example.

On Australia’s Great Barrier Reef, scientists have linked Crown of Thorn starfish outbreaks – they eat coral – to reef degradation as well. Bleaching events inevitably coincide with record-breaking temperatures, particularly 1997-’98 and 2005, the second-hottest and hottest (in the northern hemisphere) years on record, respectively. But observations on remote Pacific atolls indicate that reefs protected from fishing recover much faster after bleaching events than those that aren’t.