Corals don’t spread far from their birthplaces

From St. Louis, Mo., at a meeting of the American Association for the Advancement of Science

Creating protected marine areas in one part of the Caribbean won’t replenish distant coral reefs in the region, according to genetic research.

Because free-swimming coral larvae don’t appear to spread far from their points of origin, protected “coral gardens” at intervals of more than 100 kilometers would be too far apart to repopulate all depleted reefs in the region in our lifetimes, says Steve Palumbi of Stanford University.

“Coral gardens will need to be on every major island,” he says.

He and Steven Vollmer of the Smithsonian Tropical Research Institute in Panama studied the DNA in 262 samples of staghorn coral from the Bahamas to Panama and the Yucatán peninsula to Curaçao. They judged the corals’ relatedness by the degree of genetic similarity among the samples.

They found that related corals live in “local villages” that are separated by no more than 100 km and sometimes as little as 2 km. The genetic differences among villages indicate that larvae produced in one locale rarely become established in another, the researchers report.

Establishing “more conservation [areas] on smaller scales would probably do you more good than … protecting one large location,” Vollmer concludes.

Palumbi and Vollmer are now examining their data in the context of ocean-circulation patterns to understand how currents influence coral genetics.

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